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Abstract of thesis entitled

“An evidence-based guideline on preoperative warming of

patients undergo general anesthesia to reduce postoperative

hypothermia”

Submitted by

Cheng Tan Ning

for the degree of Master of Nursing

at The University of Hong Kong

in August 2013

Operating theatre is a cold environment and hypothermia (core body

temperature lower than 36C) is prevalent among patients undergoing operations.

Possible causes of this adverse condition include anesthetic effect, body part

exposure, blood loss, and the low room temperature in the theatre. Hypothermia

can impair wound healing, decrease drug metabolism, increase oxygen

consumption, which in turn causing respiratory distress, bradycardia as well as

atrial fibrillation. In extreme cases, it can be lethal.

Numerous research studies have explored ways of interventions and new

technologies to maintain normal body temperature of patients during operations.

However, perhaps without proper translation to clinical practice, the rate of

postoperative hypothermia still remains high in many hospital setting.

The objectives of this thesis are to systematically review the current literature

on the effectiveness of preoperative warming on reducing postoperative

hypothermia of patients undergoing general anesthesia. Data from the relevant

literature is extracted for setting up a table of evidence. Also, quality assessment is

performed. An evidence-based practice guideline for preoperative warming is

developed and its feasibility and transferability to the target patients is examined.

The purpose of the guideline is to provide better care for patients undergoing

general anesthesia.

In this thesis, preoperative forced air warming is proposed. The target setting

is the operating theatre department and day surgery centre in a local public acute

hospital. The target population is patients who undergo general anesthesia. Data is

extracted from six articles. The implementation potential of the proposed

guideline is high, because of the high transferability, feasibility and cost-effective

ratio. An evidence-based practice guideline is developed based on the evidence.

Well-designed implementation and evaluation plan are developed for the

implementation of the proposed guideline.

An evidence-based guideline on preoperative warming of patients

undergo general anesthesia to reduce postoperative hypothermia

by

Cheng Tan Ning

A thesis submitted in partial fulfillment of the requirements for

the degree of Master of Nursing

at The University of Hong Kong

August 2013

i

Declaration

I declare that this thesis thereof represents my own work, except where due

acknowledgement is made, and that it has not been previously included in a thesis,

dissertation or report submitted to this University or to any other institution for a

degree, diploma or other qualifications.

Signed ___________________________________________

Cheng Tan Ning

ii

Acknowledgements

I am heartily thankful to my supervisor, Dr Athena Hong, whose

encouragement, guidance and support over the past two years. Her generous

assistance enabled me to complete the thesis.

Lastly, I offer my regards and blessings to all of those who supported me in

any respect during the completion of the thesis

iii

Contents

Declaration………………………………………………………………………… i

Acknowledgements……………………………………………………………… ..ii

Table of Content……………………………………………………………… ..…iii

List of Appendices……………………………………………………………… .vii

Chapter 1- Introduction 1

1.1 Background………………………………………………………………1

1.2 Affirming the needs………………………………………………………2

1.2.1 Local setting 2

1.2.2 Current practice 3

1.2.2.1 Preoperative 3

1.2.2.2 Intraoperative 3

1.2.2.3 Postoperative 3

1.2.3 Clinical issue 4

1.3 Research question, objectives, and significance…………………………4

1.3.1 Research Question 5

1.3.2 Objectives 5

1.3.3 Significance 5

iv

Chapter 2-Critical Appraisal 7

2.1 Searching strategies………………………………………………………7

2.1.1 Search methodology 7

2.1.2 Keywords 7

2.1.3 Selection criteria 7

2.2 Appraisal strategy………………………………………………………8

2.3 Appraisal results………………………………………………………….8

2.3.1 Overview of the sampled studies 8

2.3.2 Summary of level of evidence 9

2.3.3 Summary of quality assessment 9

2.4 Summary of data…………………………………………………………9

2.4.1 Patients characteristics 10

2.4.2 Intervention 10

2.4.3 Comparison 10

2.4.4 Outcome measures 10

2.5 Synthesis of data………………………………………………………..10

2.6 Implication……………………………………………………………...11

v

Chapter 3-Innovation 13

3.1 Name of guideline………………………………………………………13

3.2 Target audience…………………………………………………………13

3.3 Target setting……………………………………………………………13

3.4 Target staff………………………………………………………………14

3.5 Duration of follow-up period…………………………………………..14

3.6 Procedures………………………………………………………………14

Chapter 4-Implementation Potential 16

4.1 Target audience………………………………………………………….16

4.2 Target setting……………………………………………………………16

4.3 Transferability…………………………………………………………..17

4.4 Feasibility……………………………………………………………….18

4.5 Cost-benefit ratio of the innovation…………………………………….19

Chapter 5-Developing Evidence-Based Practice Guideline 22

5.1 Background……………………………………………………………..22

5.2 Name of the evidence-based practice guideline………………………...22

5.3 Target population………………………………………………………..22

vi

5.4 Objectives……………………………………………………………….23

5.5 Practice recommendations……………………………………………...23

Chapter 6-Implementation Plan 25

6.1 Communication plan…………………………………………..………..25

6.1.1 Identifying the stakeholder 25

6.1.1.1 Department operation manager (DOM) 25

6.1.1.2 Ward manager 26

6.1.1.3 Chief of service (COS) of anesthesiology 26

6.1.1.4 Nurses and patient care assistants 26

6.1.2 The process of communicating the plan 27

6.1.3 Initiating the change 28

6.1.4 Guiding the change 28

6.1.5 Sustaining the change process 29

6.2 Pilot study……………………………………………………………….29

Chapter 7-Evaluation Plan 32

7.1 Identifying outcomes……………………………………………………32

7.1.1 Patient outcomes 32

vii

7.1.1.1 Nature of clients to be involved 32

7.1.2 Healthcare provider outcomes 33

7.1.2.1 Data collection, time of measurement 33

7.1.3 System outcomes 33

7.2 Data analysis……………………………………………………………34

7.3 Criteria for considering the guideline effective……………………........35

Chapter 8-Conclusion 36

Appendices 37

References 59

viii

List of Appendices

I. Critical appraisal checklist………………………………………………37

II. Level of evidence………………………………………………………...42

III. Evidence tables and quality assessment results………………………….43

IV. Summary of level of evidence……………………………………………55

V. Summary of quality assessment………………………………………….56

VI. Grade of recommendations………………………………………………57

VII. Evaluation form of satisfaction levels of frontline staff………..………58

1

CHAPTER 1

INTRODUCTION

Hypothermia is a common consequence among patients undergoing surgery

with the involvement of anesthesia. A person’s core temperature lower than

36°Cis considered to have hypothermia. It not only causes an unpleasant

experience but also can result with undesirable effects for the operation and

increases the risk of postoperative complications.

One of the duties of nurses is to help maintaining the patients’ body

temperature within the normal range. Currently, there are multiple warming

methods used during and after the surgical operations to fulfill the mentioned

purpose. In the existing literature, there are numerous reports exploring the

effectiveness of different interventions in maintaining the patients’ body

temperature. However, despite the tremendous effort of improvement, the

incidence of postoperative hypothermia is still high in many hospital settings.

1.1 BACKGROUND

Balance of heat production and loss by thermoregulation is the essential

mechanism of maintaining normal body temperature. Core temperature is defined

as the temperature of the central circulatory system and can be measured at the

tympanic membrane (ear drum) (Buggy & Crossley, 2000). During general

anesthesia, thermoregulation mechanism is impaired as it decreases the heat

production (inhibited vasoconstriction) while at the same time increases heat loss

(induced vasodilatation), and in a result, causing a decrease of body temperature.

Findings have shown that the core temperature of surgical patients usually drops

by 0.5°C to 1.5°C at the first hour of anesthesia (Wagner, 2006). In addition,

2

multiple factors including the cool operating room, exposure of body parts, and

blood loss, intensify the heat loss problem.

Hypothermia in perioperative environment may cause many undesirable

effects. It alters medication metabolism, causing metabolic acidosis, hypokalemia,

and nitrogen imbalance. It can also induce coagulopathy and inhibit platelet

function which may lead to an increase of blood loss. Since ischemic cardiac

mortality is the major cause of perioperative death, the risk of myocardial

infarction is higher among surgical patients with perioperative hypothermia

(Boehnlein, & Marek, 1999). Many postoperative complications are also induced

by hypothermia. For example, it increases the risk of wound infection, impairs

wound healing, and prolongs postoperative recovery and hospitalization (AORN,

2006). Severe hypothermia may cause bradycardia, premature ventricular

contraction, ventricular fibrillation, and atrial fibrillation. Since hypothermia is

common in the perioperative environment, it is a big challenge for perioperative

nursing staff to maintain normal body temperature of the patients in perioperative

setting.

1.2 AFFIRMING THE NEEDS

The temperature of an operating theatre is low compared to other places in

the hospital. Due to this reason, Hypothermia is common in perioperative setting

despite the use of warming method.

1.2.1 Local setting

I am working in a local public acute hospital with adult patients only. There

are three operating theatres in the hospital, conducting approximately 2,000

general anesthesia cases in each year. Patients undergoing operation are at risk of

developing perioperative hypothermia as they have to stay on the cold operating

3

room table for a few hours during surgical operations. Inevitably, their bodies are

exposed in the operating room with temperature about 18°C to 22°C. Heat is lost

through their exposed body parts and open body cavity. Additionally, the

antiseptic agents, infusion fluid, and irrigation fluid also cause a decrease of

patients’ body temperature, worsening the situation (Wagner, 2006).

1.2.2 Current practice

As prevention of hypothermia may help to decrease incidence of cardiac

complications, it is important to prevent hypothermia in perioperative setting

(Boulay, 2006). Similar suggestion is also stated by Dutton (2006) -- “keeping

patients warm will avoid exacerbation of hemorrhage, ischemia and acidosis”

(p.487). There are numerous methods in preventing hypothermia in perioperative

setting.

1.2.2.1 Preoperative. Patients are covered by cotton blanket and wool

blanket when they are admitted to the receiving area of the operating theatre.

1.2.2.2 Intraoperative. There are different types of warming machines used

in operating theatre. Fluid warmer is used to warm the infusion fluid, blood

products, and irrigation fluid. Forced air warming device and warming mattress

are used to provide heat to the patients’ body. The carbon dioxide gas used in

endoscopic surgeries is warmed by the carbon dioxide insufflators.

1.2.2.3 Postoperative. After the operation, patients are admitted to the

post-anesthetic care unit (PACU). In order to resume normal body temperature of

the patients, the room temperature in PACU is maintained around 24°C. Also, the

forced air warming device, warmed infusion fluid and irrigation fluid are provided

in this unit.

4

1.2.3 Clinical issue

International Journal of Evidence Based Healthcare (2011) reported that 50%

to 90% of surgical patients were resulted in perioperative hypothermia. In local

setting, all patients underwent abdominal surgery experienced hypothermia.

Shivering was observed in almost half of the patients postoperatively.

The recommended practice for the prevention of unplanned perioperative

hypothermia from the Association of Perioperative Registered Nurses (AORN,

2007) is “pre-warming the patient for a minimum of 15 minutes immediately prior

to induction of anesthesia should be considered”. Furthermore, the guideline on

management of inadvertent perioperative hypothermia in adults from the National

Institute for Health and Clinical Excellence (NICE, 2008) stated that forced air

warming should be started preoperative for patients who were going to undergo

major or intermediate surgery. In other words, warming should be started before

the patients being transferred to the operating table. American Society of

PeriAnesthesia Nurses published an evidence-based clinical practice guideline on

promotion of perioperative normothermia (ASPAN, 2009). It recommended a

provision of a minimum of 30 minutes of preoperative warming, which might

help reduce risk of subsequent hypothermia.

1.3 RESEARCH QUESTIONS, OBJECTIVES AND

SIGNIFICANCE

Although various warming measures have been used to maintain surgical

patients’ normal body temperature, incidence of hypothermia is still prevalent. In

local setting, prevention of hypothermia mostly starts at the intraoperative phrase

(i.e. the time that the patients being transferred to the operating tables) and the

5

postoperative phrase (i.e. the time that the patients being admitted to the post

anesthetic care unit). According to the international guidelines (AORN, NICE,

and ASPAN), preoperative warming should be provided to the patients undergoing

general anesthesia.

1.3.1 Research question

The research question is “Can preoperative warming prevent postoperative

hypothermia of patients undergoing general anesthesia?”

1.3.2 Objectives

The objectives of this paper are:

To systematically review the current literature on preoperative intervention in

reducing postoperative hypothermia among adult patients undergoing general

anesthesia.

To review the effectiveness of preoperative warming on preventing

postoperative hypothermia.

To determine the transferability and feasibility of the preoperative warming

on preventing postoperative hypothermia in local setting.

To set up an evidence-based guideline to reduce postoperative hypothermia

among adult patients undergoing general anesthesia.

1.3.3 Significance

Perioperative hypothermia causes many surgical complications

intraoperatively and postoperatively. It has great adverse impact on patients and

the healthcare system. Maintaining postoperative normal body temperature can

lower the risk of surgical site infection. When the hypothermia is prevented by

preoperative warming, the risk of intraoperative complications and the

postoperative surgical complications can be decreased. The patients’ recovery

6

time and hospitalization can also be shortened.

7

CHAPTER 2

CRITICAL APPRAISAL

After affirming the needs and stating the significance of an evidence-based

guideline on preoperative warming for patients undergo general anesthesia, a

critical review of the related literature is reported in this chapter.

2.1 SEARCHING STRATEGIES

2.1.1 Search methodology

A systematic search was done between 30 May 2012 and 26 August 2012.

Electronic database search was done in Medline, PubMed, CINAHL Plus, and

British Nursing Journal. The search was limited to articles published in English

from 2002 to 2012. Reference lists of the relevant articles were also reviewed.

Other sources, such as books and dissertations were also searched.

2.1.2 Keywords

The keywords used for searching are “hypothermia”, “perioperative

hypothermia”, “intraoperative hypothermia”, “postoperative hypothermia”,

“preoperative warming” and “forced air warming”. The keywords were searched

separately and then combined.

2.1.3 Selection criteria

Inclusion criteria:

Patients must be 18 years old or above.

No limitation to gender.

Patients must be under any types of elective surgery.

Patients must undergo general anesthesia.

8

All are nursing interventions to prevent and manage perioperative

hypothermia.

Exclusion criteria:

Patients younger than 18 years old

Cases are therapeutic or induced hypothermia.

Pharmacological interventions on prevention and management of

perioperative hypothermia.

2.2 APPRAISAL STRATEGY

The characteristics of the identified articles are listed in the evidence table

shown in Appendix II. In order to assess the quality of the identified articles,

methodology checklist of the Scottish Intercollegiate Guidelines Network (SIGN)

was utilized. The appraisal considers the degree of comprehensiveness of the

identified studies, reviewers’ comments, guidelines of effectiveness of presented

evidence, key questions together with the consideration of the study design, and

the judgments of the potential bias. The levels of evidence of the identified

articles were also critiqued based on the appraisal tool from SIGN. The tools used

are shown in Appendix I & II.

2.3 APPRAISAL RESULTS

2.3.1 Overview of the sampled studies

There were two thousands four hundreds and ninety five articles identified

through the keywords search. Six articles fulfilled all the inclusion criteria. The

characteristics of the included articles are explained in the evidence table

(Appendix III).

9

2.3.2 Summary of level of evidence

All the six included articles are randomized controlled trial. All included

articles were rated 1+. The summary of level of evidence is shown in Appendix

IV.

2.3.3 Summary of quality assessment

The quality of the identified articles was assessed by methodology checklist

from SIGN. The summary of the quality assessment was shown in Appendix V.

Among the six articles, four of them were rated ++ (Horn et al., 2012; Kim et

al., 2006; Melling et al., 2001; Ng et al., 2003). Although the investigators were

not blinded in all the articles, this did not affect the internal validity of the studies

because the outcome measure (core temperature) is subjective data. All of the four

articles well covered most of the areas. The concealment methods were used

adequately to minimize the contamination of the randomization. The

characteristics of the subjects in these four articles were clearly described. A

comparison between intervention group and control group was also included.

Besides the four articles mentioned, there were another two identified articles

among the six included articles and they were rated + (De Wittee et al., 2010;

Vanni et al., 2003). Although most of the areas were covered in these two articles,

the sample size of these studies were small (27 and 30 respectively).

All of the six mentioned articles were carried out at one site. And the

blinding of the investigators was not mentioned in all the six papers.

2.4 SUMMARY OF DATA

The data extracted from the six identified articles were listed in the evidence

tables shown in Appendix III.

10

2.4.1 Patients characteristics

There were 1013 adult subjects who underwent different types of elective

surgery, including laparoscopic, open abdominal, breast, orthopedic, colorectal,

vascular, hernia, and off pump coronary artery by-pass surgery. The age of the

subjects ranged from 39 to 66. The male-to-female ratio was 1:2. There is no

difference in subject’s characteristics between the intervention and the control

group.

2.4.2 Intervention

All included articles used forced air warming device as the warming

technique. The intervention was used preoperatively. When describing the

interventions and results, all articles made clear distinction of the study phrases

(preoperative, intraoperative, & postoperative). Time of the intervention varied

from 10 to 60 minutes preoperatively. There was no standardized recommendation

on the duration of the intervention.

2.4.3 Comparison

Cotton blankets were provided to the control group as it is the usual practice

in the operation room.

2.4.4 Outcome measures

The outcome measure of all included articles was the core temperature of the

patients. Three studies assessed the skin temperature of the patients while another

two assessed the degree of shivering postoperatively.

2.5 SYNTHESIS OF DATA

The provision of preoperative warming was suggested among all included

articles for preventing postoperative hypothermia. There were significant benefits

11

associated with preoperative warming. One of the articles concluded that the use

of preoperative warming could shorten the time to resume normal body

temperature of the patients in the PACU (Ng et al., 2003). Another article

concluded that the preoperative warming could lower the rate of hematoma and

seroma (Melling, 2001). All articles mentioned that they used forced air warming

device as intervention. The effectiveness of the forced air warming device had

been reviewed in numerous studies and it was recommended by the AORN and

NICE for maintaining patients’ normal body temperature. The suggested

intervention time varied among the articles. One article suggested that warming

patients 10 minutes preoperatively could prevent hypothermia for surgery time

between 30 minutes and 90 minutes (Horn, 2012). Another article suggested

prewarming patients for 60 minutes can prevent hypothermia for surgery time of

120 minutes (Vanni, 2003). The length of preoperative phrase and the operating

time varied across different cases. There was no standardized recommendation of

the length of preoperative warming. Mentioned in the articles, even 10 minutes of

preoperative warming could bring significant effect on preventing postoperative

hypothermia. Therefore, the preoperative warming should be started once the

patients admitted to the operating theatre.

2.6 IMPLICATION

Systematic review indicated preoperative forced air warming was effective in

preventing and managing postoperative hypothermia. Based on the results from

the literature reviews, providing preoperative warming by forced air warming

were recommended to those patients undergoing general anesthesia on the arrival

to the operating theatre, in tandem with the continuous monitoring of patients’

body temperature.

12

The target group of the intervention will be patients aged 18 years old or

above and plan to have elective surgery undergo general anesthesia. The body

temperature of all eligible patients will be measured on the arrival of the operating

theatre as the baseline data. For the hyperthermic patients, no preoperative

warming will be provided, or otherwise, preoperative warming will be given. The

body temperature of the patients will be monitored by anesthetists intraoperatively,

after the admission to the PACU, and before the discharge from the PACU.

Perioperative hypothermia is a common but preventable problem. In current

practice, forced air warming has already been provided intraoperatively and

postoperatively. From the research papers, it is concluded that extending active

warming to the preoperative phrase adds minimal additional cost but it brings

additional beneficial effects.

13

CHAPTER 3

INNOVATION

In current practice, active warming is provided during and after operation.

However, the rate of postoperative hypothermia is still high. The effectiveness of

preoperative forced air warming in preventing and managing postoperative

hypothermia is discussed in the previous chapter. All six included articles

recommended that medical staff should provide preoperative warming for patients

in order to reduce the occurrence of postoperative hypothermia. After affirming

the needs of the patients, an evidence-based innovation is proposed.

3.1 NAME OF GUIDELINE

Evidence-based guideline on preoperative warming of patients undergo

general anesthesia.

3.2 TARGET PARTICIPANTS

The target participants are all adult patients who schedule to have surgical

operations with general anesthesia. In addition, they should fulfill the selection

criteria and agree to participate in the pilot program by providing an informed

consent.

3.3 TARGET SETTING

Pilot program of the new guideline will be held in the Operating Theatre

Department of a public hospital on Hong Kong Island. The department equips

with three operating theatres and three induction rooms.

If the proposed innovation is proved successful, it will be implemented in all

operating theatres of the hospital located in the Operating Theatre Department and

14

Day Surgery Centre. The estimated number of patients being benefited from the

new guideline is 2,000 as there are approximately 2,000 patients scheduled for

general anesthesia in each year. All nurses work in the Operating Theatre

Department and Day Surgery Centre will conduct the preoperative warming for

patients.

3.4 TARGET STAFF

Target staffs of the pilot program are anesthetists and nurses working in the

Operating Theatre Department.

3.5 DURATION OF FOLLOW-UP PERIOD

In the pilot program, the duration of the follow-up period is three months.

Since there are approximately 2,000 general anesthesia cases per year, there will

be approximately 500 general anesthesia cases take part in the pilot program.

3.6 PROCEDURES

In the induction rooms, nurses will measure the body temperature of the

patients by using the tympanic thermometer (Braun Tympanic Thermometer,

ThermoScan). Purssell et al. (2009) concluded that the ThermoScan (Braun

Tympanic Thermometer) is a reliable instrument on tympanic temperature

measurement. This tympanic thermometer has been widely used in all public

hospitals in Hong Kong. If the patients fulfill the selection criteria of the program,

forced air warming will be provided in the induction room for the patients until

they are transferred to the operating theatres. The temperature management unit

(Bair Hugger®) model 505 of 3M Company will be used to provide forced air

warming. The body temperature of the patients in the intraoperative phase will be

measured and recorded by anesthetists. The body temperature of the patients in

15

the post anesthetic care unit will be measured at the time of arrival and before

being discharged to the ward. Duration of the given preoperative forced air

warming and the types of operation will be recorded.

16

CHAPTER 4

IMPLEMENTATION POTENTIAL

Before implementing the evidence-based innovation into current practice, the

implementation potential of the proposed innovation should be assessed. In this

chapter, the transferability of findings, feasibility of innovation implementation

and the cost-benefit ratio of the innovation are assessed.

4.1 TARGET AUDIENCE

The target audience must be 18 years old or above. Men or women are

welcome to participant in the innovation. All of them must be scheduled for

elective surgery (of any types) under general anesthesia.

Patients who are younger than 18 years old; schedule for operation requiring

therapeutic or induced hypothermia; or have tympanic temperature higher than

37.5oC during the assessment in the induction room will be excluded.

4.2 TARGET SETTING

The target setting is a public hospital located at Hong Kong Island, with five

operating theatres and five induction rooms. The pilot program will be

implemented in three induction rooms of the Operating Theatre Department.

The operating theatre nurses will be responsible for the assessment of

tympanic temperature of the patients before and after the operation.

Anesthetists will be involved in recording the body temperature of the

patients during operations.

All of them are invited to take part in the innovation.

17

4.3 TRANSFERABILITY OF THE FINDINGS

For the six included articles discussed in Chapter 2, the studies were

performed in the operating theatres for elective surgery. Their recommendation

fits the target setting in which it mainly provides elective surgery services.

In the included articles, the patients were adults who had scheduled for

elective surgeries. The age of the patients ranged from 39 to 66. The types of

surgeries performed in the articles were laparoscopic colorectal surgery, breast

surgery, vascular surgery, abdominal surgery, orthopedic surgery and general

surgery. The population served in the target setting is adults (with mean age of 52)

who have scheduled for elective surgery. The types of scheduled surgeries include

laparoscopic surgery, breast surgery, vascular surgery, abdominal surgery,

orthopedic surgery, urology surgery and general surgery. The target population in

the studies is very similar to that in the target setting.

There is no conflict between the innovation and the prevailing philosophy of

the target setting. The mission of the healthcare team is to provide holistic care to

every patient. We understand that patients require more intensive care in the

perioperative setting. Thus, the proposed innovation is developed based on similar

philosophy of patient care.

In the target setting, there are approximately 2,000 elective surgery cases

every year. There will be approximately 2,000 patients benefit from the innovation

every year.

The covered period of the innovation is from the moment when patients

arrive the induction rooms to the time right before they are transferred to the

operating table. The result of the innovation will be evaluated during the time

when the patients are in the post anesthetic care unit. The time of implementation

18

and evaluation are similar to the included articles.

The findings are transferable because the target setting, target audience and

the philosophy of care of the target setting are similar to the six included articles.

4.4 FEASIBILITY

Nurses of the operating theatres will have freedom to carry out the

innovation. They are also free to withdraw from the innovation at any time.

The tympanic temperature measure during preoperative and postoperative

phases by nurses is routine practice. Also, body temperature assessment by the

anesthetists is part of their anesthetic assessments. For the innovation, nurses will

provide forced air warming blankets to patients if they fulfill the inclusion criteria.

In current practice, nurses only provide extra wool blankets to patients on request.

By observation, half of the patients, regardless of their sex, requested for extra

blankets. In order to launch the innovation, it may bring extra workload to the

nurses for applying the forced air warming blankets in the induction room. In fact,

the wool blankets are actually heavier than the forced air warming blankets. In

this sense, the innovation can reduce the workload of nurses.

The administration of the target hospital supports the utilization of

evidence-based practices to enhance the quality of care provided to the patients.

This is embodied by the adoption of evidence-based Chinese Medicine service

into their palliative care in 2004 and the integration of evidence-based nursing

care to acute stroke patients in 2005. As the proposed innovation is to prevent

postoperative hypothermia and reduce the risk of postoperative complications,

patients’ levels of comfort may improve and the cost of hospital stay may also

reduce. This goes in parallel to the direction of the administration of the target

hospital, therefore, it is expected that they will support the proposed innovation.

19

For nursing staffs, there is not much additional workload for providing

preoperative warming. Similar to the current practice, they need to provide the

forced air warming during intraoperative and postoperative phases. The proposed

innovation is a simple extension of the current practice. Moreover, they are well

equipped with the knowledge on applying the forced air warming device. There is

no new knowledge or extra skills required for the innovation.

As the proposed innovation only involves the nursing staffs of the

operating theatres, there will be no conflicts between departments.

Although new knowledge or extra skill are not required, a training session of

about 15 minutes will be provided to all nurses of the Operating Theatre

Department. The affirmed needs, objectives, and expected outcome of the

innovation will be explained in the training session. The inclusion and exclusion

criteria of the patients will be explained. The concerns and feedbacks and the

evaluation of the pilot program will be discussed during the training sessions.

In each induction room, there is one backup forced air warming device.

These backup forced air warming devices can be used to provide preoperative

warming in the induction rooms during the pilot phase. After the pilot program,

five more forced air warming devices will be needed.

It is feasible to adopt the innovation as the administration of the target setting

support the evidence-based practice. There is no additional knowledge and skill

needed for the staff to implement the innovation.

4.5 COST-BENEFIT RATIO OF THE INNOVATION

After the assessment of transferability of the findings and feasibility of the

innovation in the target setting, the cost-effectiveness of the innovation is

assessed.

20

Hyperthermia is a risk for patients. Patients in induction will be provided the

forced air warming while they are waiting. Although the forced air warming

device has an alarming system to monitor the output temperature and stops

automatically once the temperature exceeds the pre-set temperature, there is a risk

of being too hot for the patients. The risk can be reduced by asking the patients’

feeling of heat intermittently.

Another risk to the patients is a thermal burn of patients’ skin due to the

direct contact of the warming device. Siddik-Sayyid (2010) reported one thermal

burn case caused by forced air warming. The patient had a first degree burnt over

the upper arm and shoulder area resulting from a direct contact with the warming

device host after the operation. Although the target audience of the innovation will

be reminded, there is a risk of thermal burn for the patients with poor thermal

sensation. In order to reduce the risk of thermal burn, the nurses will be reminded

to follow the existing guidelines on using forced air warming devices.

The aim of the innovation is to reduce postoperative hypothermia. There are

many postoperative complications caused by postoperative hypothermia,

including pain, blood loss, increased risk of myocardial infarction, delayed wound

healing, and increased risk of infection, lengthened hospital stay and increased

cost. The innovation can reduce postoperative hypothermia and thus reduce the

risk of postoperative complications.

As mentioned earlier, some backup forced air warming devices can be used

for the pilot study. After the pilot, five extra forced air warming devices will be

needed with HKD10000 per device. There is no nonmaterial costs because no

extra manpower is required for implementing the innovation.

In comparison, the material cost of not implementing the innovation includes

21

the cost for purchasing new wool blankets to replace the old one and the cost of

laundry service. For the current practice, the nonmaterial cost includes the

manpower to manage the stock and logistic of the wool blankets. Moreover,

another cost is the additional cost for patients with postoperative hypothermia

staying in the post anesthetic care unit for longer than they should to resume their

normal body temperature (Just, 1992).

To conclude, the findings of the included articles are transferable. Secondly,

the target population and setting are similar to that in the included articles. In

other words, the proposed innovation will fit the target setting and is feasible to

implement in the target setting. Thirdly, there is no reason the administrators

would reject the proposed innovation. Fourth, nurses do not need to acquire new

knowledge and skills for implementing the proposed innovation. Finally, the

potential benefit of the proposed innovation to the patients decreases the number

of postoperative hypothermia that may cause postoperative complications. As a

result, the decrease in postoperative complications will reduce the costs of

hospital stay.

22

CHAPTER 5

DEVELOPING EVIDENCE-BASED PRACTICE

GUIDELINE

In this chapter, the guideline developed based on the recommendations of the

articles that were critically appraised in previous chapter is reported.

5.1 BACKGROUND

One of the core aspects of perioperative nursing is to maintain normal body

temperature of the patients during the perioperative period. The forced air

warming devices are used to maintain body temperature of patients during and

after the operations. However, the rate of postoperative hypothermia is still high.

The six critically appraised articles recommended to provide preoperative

warming to prevent postoperative hypothermia.

The levels of evidence and grades of recommendation were rated by the

development guide of Scottish Intercollegiate Guidelines Network (SIGN, 2011).

The levels of evidence range from 1++ to 4. The grades of recommendation range

from A to E.

5.2 NAME OF THE EVIDENCE BASED PRACTICE

GUIDELINE

An evidence-based guideline on preoperative warming of patients

undergoing general anesthesia to reduce postoperative hypothermia

5.3 TARGET POPULATION

Patients must fulfill the following criteria:

23

18 years old or above

scheduled for elective surgery under general anesthesia

with tympanic temperature lower than 37.5oC

not scheduled for operation of therapeutic hypothermia or requires

induced hypothermia

Patients who are under 18 years old, pregnant, with endocrine diseases, or

having infection will be excluded. As well, patients with physical status that are

categorized at level 3 or above based on the classification from the American

Society of Anesthesiologists (ASA) will also be excluded.

5.4 OBJECTIVES

To maintain normal body temperature of patients preoperatively

To maintain normal body temperature of patients postoperatively

5.5 PRACTICE RECOMMENDATIONS

Recommendation 1

For patients scheduled for elective surgery under general anesthesia,

preoperative warming should be provided for at least 10 minutes before operation.

Evidence:

“Pre-warming period of 10 min, or if possible 20 min, before surgery

under general anesthesia” (Horn et al., 2012, 1+)

“Pre-warming should be considered as part of the anesthetic

management when patients are at risk of postoperative hypothermia.”

(De Witte et al., 2010, 1+)

“Warming patients before clean surgery seems to aid the prevention of

postoperative wound infection.” (Melling et al., 2001, 1+)

“Actively pre-warming the patient with forced air warming device

24

before the induction is effective to lessen the degree of redistribution

hypothermia.” (Kim et al., 2005, 1+)

Grade of recommendation: A

Recommendation 2

Forced air warming device should be used as a preoperative warming device.

Evidence:

“Active warming using forced air blanket before the induction of

anesthesia reduced the incidence and degree of redistribution

hypothermia.” (Kim et al., 2005, 1+)

“We conclude that forced-air warming was significantly more effective

and cost-effective in maintaining perioperative normothermia. (Ng et al.,

2003, 1+)

“The forced air warming was most efficient in maintaining perioperative

normothermia.” (Ng, 2003, 1+)

“Preoperative forced air warming prevented postoperative hypothermia

and shivering, and offered good conditions for early tracheal extubation.”

(Vanni et al. , 2002, 1+)

Grade of recommendation: A

25

CHAPTER 6

IMPLEMENTATION PLAN

The needs of the innovation are affirmed. The transferability and feasibility

of the findings and the cost-benefit ratio of the innovation are also discussed in the

previous chapters. The evidence-based guideline on preoperative warming of

patients undergoing general anesthesia to reduce postoperative hypothermia is

developed based on the findings of the included articles. However, without an

implementation plan, an innovation plan is just a stack of papers no matter how

well thought out it is. The implementation plan includes communication plan and

pilot testing plan to test the guideline.

6.1 COMMUNICATION PLAN

In order to implement the innovation successfully, it is important to have a

communication plan. The aims of the communication plan are to get support from

the stakeholders and to gain consensus and agreement from the frontline staffs.

6.1.1 Identifying the stakeholders

The stakeholders can affect or be affected by the proposed evidence-based

guideline. They include administrators (department operation manager and ward

manager), doctors (chief of service) and users of the proposed evidence-based

guideline (nurses and patient care assistants). In order to gain their support and

minimize resistance, detailed information of the innovation will be discussed with

them. The details include the needs, importance, and significance of the

innovation.

6.1.1.1 Department operation manager (DOM).The department operation

manager has the duty to review and approve the evidence-based guidelines

26

implementing in the department. The proposed evidence-based guideline needs

her approval before the implementation. On the other hand, she is in charge of the

program budgets and facilitates programs of the department. Since the innovation

needs additional forced-air warming devices, the purchase of these extra devices

require financial support from the department operation manager.

6.1.1.2 Ward manager. Ward manager is the person-in-charge of the

operating theatre. She plays an important role to communicate with the

anesthetists who are responsible for patient care in the department. She is one of

the important stakeholders because she can assign work to frontline staffs

including nurses and patient care assistants.

6.1.1.3 Chief of service (COS) of anesthesiology. The anesthetists are

responsible for patient care in the operating theatre. The approval and agreement

from the head of anesthetists, the Chief of Service, is needed before implementing

the proposed evidence-based guideline. It is because all anesthetists in this

hospital will follow the guideline approved by the COS. The COS has the duty to

disseminate the new guidelines to his staff. He helps to communicate with all

anesthetists in the hospital.

6.1.1.4 Nurses and patient care assistants. Nurses and patient care assistants

are the most important stakeholders because they are the personnel who carry out

the innovation. Their workload may be increased because of the innovation. In the

proposed evidence-based guideline, they are the most affected group. In order to

gain their understanding and support, the details of the guideline will be discussed

with them. They will be invited to ask questions and raise concern about the

guideline.

27

6.1.2 The Process of Communicating the Plan

As mentioned, it is important to gain support from the stakeholders. In order

to gain their support, the sequence of communication with these four groups of

stakeholders is important. The sequence of communication will start from the

managerial level to the frontline staffs who are involved in this innovation.

The ward manager will be the first stakeholder to be approached. The

reviewed data from the critical review and the needs for improving the current

practice will be discussed with her. The details of the guideline will be explained

in order to gain her feedback and recommendation. The modified proposal based

on her recommendations will be given to her again for approval.

After gaining the approval from the ward manager, the department operation

manager (DOM) will be the next stakeholder to be communicated with. The

proposed innovation will be explained in the bimonthly department meeting. The

details of the proposed innovation will be explained in a presentation. The

concerns and recommendations from DOM will be used for modifying the

innovation proposal.

Afterwards, the approved innovation proposal will be explained to the Chief

of Service (COS). The details of the proposed innovation will be explained, which

include the aims, needs, and reviewed data from the critical appraisal, significance,

transferability, feasibility, and cost-benefit ratio of the innovation. The details of

changes in the current practice will also be explained in order to gain his approval.

Finally, the most important group of stakeholders will be communicated after

the approval from the managerial level of different parties. Formal training

sessions will be arranged for the frontline staffs including nurses and patient care

assistants in the operating theatre department. The training sessions will be held

28

during working hours. The aim, needs, significance, cost-benefit ratio of the

innovation will be explained during the training. The details of the guideline will

also be explained. In order to gain their support, their concerns and questions will

also be addressed in the training sessions.

6.1.3 Initiating the change

To initiate changes in the current practice, strong evidence is needed. The

evidence will be explained to the stakeholders to gain their support to the change

the current practice. The needs of change will be explained by comparing the rates

of postoperative hypothermia globally and locally based on the critical appraisal

data. From the critical appraisal, 50% to 90% of surgical patients are estimated to

result in postoperative hypothermia. In the target hospital, around 50% of the

surgical patients resulted in postoperative hypothermia. In view of the methods

used in keeping patients warm preoperatively, providing blankets is the most

commonly used method globally and locally.

To have a clear vision about the urge of a change, the undesirable effects and

complications due to postoperative hypothermia will be shown and explained. The

undesirable effects include altered medication metabolism, coagulopathy, increase

in blood loss and myocardial infarction rate (Boehnlein, & Marek, 1999). The

complications of hypothermia include increased rate of wound infection, delayed

wound healing, and prolonged postoperative recovery and hospitalization (AORN,

2006). In order to facilitate an attitude change among the stakeholders, the

severity of the clinical issue and the consequence of not changing the current

practice have to be explained clearly.

6.1.4 Guiding the change

The innovation will be guided by the aim, which is to maintain normal

29

temperature of postoperative patient. Everyone should go with the same direction

towards the aim. Before starting the change, the aim of the change has to be

clearly explained to the stakeholders. A time frame will be needed to guide the

pace of change. It will take about two weeks to gain approval from the managerial

levels. The proposed guideline will be piloted in daily practice for three months.

Based on the clinical data of patients and feedbacks from frontline staffs, the

guideline will be evaluated and revised after the pilot study. In order to cover all

involved frontline staffs (14 nurses and 6 patient care assistants in the operating

theatre department), two identical training sessions will be arranged during

working hours. The guideline will be delivered to all frontline staffs by internal

email. Several hard copies will be ready for reference during the training sessions.

6.1.5 Sustaining the change process

In order to maintain the change, adequate facilitation and support to the

frontline staffs will be needed. The proposed guideline will be revised and

modified based on the comments and concerns from the frontline staffs. The

effectiveness of the change will be evaluated based on the clinical data (e.g. the

rate of postoperative hypothermia). The quality and utilization rate of the

innovation will be accessed by annual audit. The results will be disclosed to the

frontline staffs through internal email and department meeting. According to the

document control policy of the hospital, the evidence-based guideline will be

revised systematically every three years.

6.2 PILOT STUDY

Before implementing the proposed evidence-based guideline, the feasibility

of the proposed innovation has to be determined. The proposed evidence-based

guideline will be piloted for three months. The proposed guideline will be

30

evaluated after that. The preoperative and postoperative body temperature of the

patients will be measured and compared. The time of forced-air warming device

given to the patients preoperatively will be recorded. The feedbacks from the

frontline staffs about the proposed guideline will be gathered. The proposed

guideline will be revised and modified based on the evaluation.

In local setting, there are about 160 patients undergoing general anesthesia

every month. Patients who receive preoperative care are located in the

post-anesthetic care unit (PACU). Nurses and patient care assistants working in

PAUC are responsible to provide care to patients before and after the surgical

operations. Therefore, the pilot study will be held there.

After gaining the approval from the managerial levels, the pilot study will be

implemented from 1st August 2013 to 31

st October 2013. Before the

implementation of the pilot study, a training session will be arranged for the

nurses and patient care assistants who work in the PACU. There are three nurses

and two patients care assistants working in this unit. All nurses and patient care

assistants working in the PACU have completed in-house training on

perioperative patient care. They are competent in body temperature measurement

and the use of forced-air warming devices. Thus, the reliability of the pilot study

can be ensured. The aim, need, and significant of proposed guideline will be

explained to them during the formal training session.

When patients admit to the operating theatre department, patient care

assistant in the PACU will measure patients’ tympanic temperature, blood

pressure, oxygen saturation. For patients who fulfill the inclusion criteria of the

target population mentioned in Chapter 5, preoperative force-air warming will be

provided. The duration of preoperative forced-air warming provided will be

31

recorded. After surgical operation, patients will be transferred back to the PACU.

The tympanic temperature, blood pressure, oxygen saturation of the patients will

be closely monitored and recorded.

The effectiveness of the proposed innovation can be evaluated by analyzing

the data recorded preoperatively and postopertively. Changes of patients’ body

temperature preoperatively and postopeatively will be compared. The duration of

the forced-air warming provided and duration of the surgical operations will be

analyzed. A formal meeting will be held in the end of November 2013 after the

analytical process of the clinical data. The evaluation result will be shared with

the frontline staffs involved in the pilot study. Their concerns and feedback of the

pilot study will be discussed during the meeting. The guideline will be revised and

modified based on the clinical data and the feedbacks from the frontline staffs.

The revised and modified guideline will be sent to the ward manager for her final

approval before the full-scale implementation of the guideline.

32

CHAPTER 7

EVALUATION PLAN

The effectiveness of a proposed guideline should be evaluated continuously

or periodically. Therefore, the evaluation plan of a guideline should be designed

along with the development of the guideline. The purpose of this evaluation plan

is to evaluate the effectiveness of preoperative warming in maintaining normal

postoperative body temperature of patients undergoing general anesthesia.

7.1 IDENTIFYING OUTCOMES

To evaluate the effectiveness of a guideline, the patient outcomes and system

outcomes should be identified and analyzed.

1.3.4 Patient outcomes

The effectiveness of a guideline can be evaluated by assessing the clinical

benefits of the innovation. The aim of preoperative warming is to maintain the

normal body temperature postoperative of patient undergoing general anesthesia.

The primary outcome is the postoperative body temperature of patients.

There is secondary outcome. The forced-air warming will be provided to

patients before the start of the surgical operation. The preoperative body

temperature of patients will be maintained in normal range.

7.1.1.1 Nature of clients to be involved. The target population will be

patients who are 18 years old or above. They must be scheduled for any type of

elective surgery under general anesthesia. Patients with body temperature higher

than 37.5C during the first assessment in the preoperative waiting area will be

excluded.

The body temperature of the patients will be measured every 5 minutes after

33

they are admitted to the operating theatre department. The body temperature will

be measured by tympanic thermometer (Braun Tympanic Thermometer,

ThermoScan). This tympanic thermometer is widely used in all public hospitals in

Hong Kong. Purssell et al. (2009) reported that the ThermoScan is a reliable

instrument on tympanic temperature measurement.

1.3.5 Healthcare provider outcomes

In order to evaluate the effectiveness of the guideline, feedback from the

frontline staffs is important. The satisfactory level of implementation of the new

guideline will be evaluated.

7.1.2.1 Data collection, time of measurements. The satisfactory level of the

frontline staffs will be evaluated by a questionnaire (Appendix VII). To collect the

quantitative data, Likert scale will be used. Three open-ended questions will be

used to invite frontline staffs to express their concerns and feeling.

The questionnaires will be distributed to the frontline staffs at the end of the

pilot program.

1.3.6 System outcomes

The effectiveness of the guideline to the system has to be evaluated. The

utilization of the innovation will be evaluated by internal audit. The number of

patients who meet the inclusion criteria will be compared with the number of

patients received preoperative warming. The percentage of patients received

preoperative warming will reflect the utilization of the innovation.

The reasons of the target population not willing to receive preoperative

warming will be analyzed. The expected adverse effect of the innovation will be

hyperthermia. The clinical data including body temperature of patients before

forced-air warming provided, health history of patients, and duration of the

34

forced-air warming provided will be analyzed.

From the management point of view, cost of the innovation will be evaluated.

Despite the incremental cost of buying more forced-air warming devices for

patients in preoperative waiting area, the cost of maintenance and replacement of

forced-air warming devices will be evaluated.

7.2 DATA ANALYSIS

The primary outcome of the innovation is the normal body temperature

(36C to 37.4C). According to International Journal of Evidence Based

Healthcare (2011), 50% to 90% of surgical patients resulted in postoperative

hypothermia whereas 100% of patients experienced postoperative hypothermia in

this hospital. The percentage of postoperative body temperature of patients

maintained between 36C and 37.4C reflects the effectiveness of the innovation.

The data will be analyzed by paired t-test at the 5% significant level.

Number of patients involved in the evaluation is calculated according to the

percentage of patients who maintain postoperative body temperature with

preoperative warming offered. The data will be analyzed by the Russ Lenth’s

power and sample size calculator.

The primary variable is the postoperative body temperature. From the

reported data from De Wittee et al. (2010), the standard deviation of tympanic

temperature of an increase of temperature in 1C is 0.5C. With power set at 80%

and significant level at 0.05, the number of patients involved is 10. The proportion

of patients with normal body temperature (tympanic temperature between 36C

and 37.4C) postoperatively can be calculated by using paired t-test at the 5%

significance level.

35

7.3 CRITERIA FOR CONSIDERING THE GUIDELINE

EFFECTIVE

The guideline will be considered as effective if the following three criteria

are fulfilled.

First, the aim of the proposed guideline is to maintain normal body

temperature of patients postoperatively. Therefore, the first criterion is the

patient’s core body temperature can be maintained between 36C and 37.4C

postoperatively.

Secondly, the guideline will be regarded as effective if 80% of the frontline

staffs are satisfied with the implementing the new guideline.

Finally, in view of system outcome, the guideline will be regarded as

effective if the utilization rate of the new guideline is 100%.

36

CHAPTER 8

CONCLUSION

Postoperative hypothermia is a common problem in operating theatre all over the

world. Despite multiple warming strategies provided for patients to prevent

postoperative hypothermia during operations and after operations, the number of

patients suffered from postoperative hypothermia is still high. Recently, there is a

proposal of new approach of preoperative warming. In this thesis, an

evidence-based guideline is introduced to reduce the complications caused by

postoperative hypothermia.

After affirming the need of innovation, an evidence-based guideline is

developed. The guideline is derived based on the data drawing from six critical

appraised studies.

Examining the transferability, feasibility, and cost-benefit ratio, the

implementation potential of the evidence-based guideline was affirmed. In order

to implement the evidence-based guideline to daily practice, the support from

stakeholders is needed. A communication plan is developed for this purpose.

Specifically, the needs, aims, significance of the evidence-based guideline will be

explained to the stakeholders. Where necessary, modification of the

evidence-based guideline will be made before the full-scale implementation.

The results of implementing the guideline will be evaluated. The

evidence-based guideline will be considered as effective if there is an increase of

proportion of patients maintaining their normal body temperature postoperatively.

37

APPENDIX

Appendix I: Critical Appraisal Checklist

Section 1. Identifies the study, the reviewer, the guideline for which the

paper is being considered as evidence, and the key question(s) it is expected to

address. The reviewer is asked to consider a series of aspects of RCT design and

to make a judgment as to how well the current study meets this criterion. Each

relates to an aspect of methodology that research has shown makes a significant

difference to the conclusions of a study.

For each question in this section you should use one of the following to

indicate how well it has been addressed in the study:

Well covered

Adequately addressed

Poorly addressed

Not addressed (i.e. not mentioned, or indicates that this aspect of study

design was ignored)

Not reported (i.e. mentioned, but insufficient detail to allow assessment to

be made)

Not applicable.

1.1 The study addresses an appropriate and clearly focused question.

Unless a clear and well defined question is specified, it will be difficult to assess

how well the study has met its objectives or how relevant it is to the question you

are trying to answer on the basis of its conclusions.

1.2 The assignment of subjects to treatment groups randomized. Random

allocation of patients to receive one or other of the treatments under investigation,

38

or to receive either treatment or placebo, is fundamental to this type of study. If

there is no indication of randomization, the study should be rejected. If the

description of randomization is poor, the study should be given a lower quality

rating. Processes such as alternate allocation, allocation by date of birth, or day of

the week attending a clinic are not true randomization processes and it is easy for

a researcher to work out which patients received which treatment. These studies

should therefore be classed as Controlled Clinical Trials rather than RCTs.

1.3 An adequate concealment method is used. Allocation concealment

refers to the process used to ensure that researchers are unaware which group

patients are being allocated to at the time they enter the study. Research has

shown that where allocation concealment is inadequate, investigators can

overestimate the effect of interventions by up to 40%. Centralized allocation,

computerized allocation systems, or the use of coded identical containers would

all be regarded as adequate methods of concealment, and may be taken as

indicators of a well conducted study. If the method of concealment used is

regarded as poor, or relatively easy to subvert, the study must be given a lower

quality rating, and can be rejected if the concealment method is seen as

inadequate.

1.4 Subjects and investigators are kept “blind” to treatment allocation.

Blinding refers to the process whereby people are kept unaware of which

treatment an individual patient has been receiving when they are assessing the

outcome for that patient. It can be carried out up to three levels. Single blinding is

where patients are unaware of which treatment they are receiving. In double blind

studies neither the doctor nor the patient knows which treatment is being given. In

very rare cases studies may be triple blinded, where neither patients, doctors, nor

39

those conducting the analysis are aware of which patients received which

treatment. The higher the level of blinding, the lower the risk of bias in the study.

1.5 The treatment and control groups were similar at the start of the

trial .Patients selected for inclusion in a trial must be as similar as possible. The

study should report any significant differences in the composition of the study

groups in relation to gender mix, age, stage of disease (if appropriate), social

background, ethnic origin, or comorbid conditions. These factors may be covered

by inclusion and exclusion criteria, rather than being reported directly. Failure to

address this question, or the use of inappropriate groups, should lead to the study

being downgraded.

1.6 The only difference between the groups is the treatment under

investigation. If some patients received additional treatment, even if of a minor

nature or consisting of advice and counseling rather than a physical intervention,

this treatment is a potential confounding factor that may invalidate the results. If

groups were not treated equally, the study should be rejected unless no other

evidence is available. If the study is used as evidence it should be treated with

caution.

1.7 All relevant outcomes measured in a standard, valid and reliable way.

The primary outcome measures used should be clearly stated in the study. If the

outcome measures are not stated, or the study bases its main conclusions on

secondary outcomes, the study should be rejected. Where outcome measures

require any degree of subjectivity, some evidence should be provided that the

measures used are reliable and have been validated prior to their use in the study.

1.8 What percentage of the individuals or clusters recruited into each

treatment arm of the study dropped out before the study was completed? The

40

number of patients that drop out of a study should give concern if the number is

very high. Conventionally, a 20% drop out rate is regarded as acceptable, but this

may vary. Some regard should be paid to why patients dropped out, as well as

how many. It should be noted that the dropout rate may be expected to be higher

in studies conducted over a long period of time. A higher dropout rate will

normally lead to downgrading, rather than rejection of a study.

1.9 All the subjects are analyzed in the groups to which they were

randomly allocated (intention to treat analysis.)In practice, it is rarely the case

that all patients allocated to the intervention group receive the intervention

throughout the trial, or that all those in the comparison group do not. Patients may

refuse treatment, or contra-indications arise that lead them to be switched to the

other group. If the comparability of groups through randomization is to be

maintained, however, patient outcomes must be analyzed according to the group

to which they were originally allocated irrespective of the treatment they actually

received. (This is known as intention to treat analysis.) If it is clear that analysis

was not on an intention to treat basis, the study may be rejected. If there is little

other evidence available, the study may be included but should be evaluated as if

it were a non-randomized cohort study.

1.10 Where the study is carried out at more than one site, results are

comparable for all sites. In multi-site studies, confidence in the results should be

increased if it can be shown that similar results were obtained at the different

participating centers.

Section 2. Relates to the overall assessment of the paper. It starts by rating

the methodological quality of the study, based on your responses in Section 1 and

using the following coding system:

41

++ All or most of the criteria have been fulfilled. Where they have not been

fulfilled the conclusions of the study or review are thought very unlikely to

alter.

+ Some of the criteria have been fulfilled. Those criteria that have not been

fulfilled or not adequately described are thought unlikely to alter the

conclusions.

- Few or no criteria fulfilled. The conclusions of the study are thought likely

or very likely to alter.

The code allocated here, coupled with the study type, will decide the level of

evidence that this study provides. The aim of the other questions in this section is

to summarize your view of the quality of this study and its applicability to the

patient group targeted by the guideline you are working on (Scottish

Intercollegiate Guidelines Network, 2008).

42

Appendix II: Level of Evidence

Level of

evidence

1++ High quality meta-analyzes, systematic reviews of RCTs, or RCTS

with a very low risk of bias

1+ Well conducted meta-analyzes, systematic reviews, or RCTs with a

low risk of bias

1- Meta-analyzes, systematic reviews, or RCTs with a high risk of bias

2++ High quality systematic reviews of case control or cohort studies

High quality case control or cohort studies with a very low risk of

confounding or bias and a high probability that the relationship is

causal

2+ Well conducted case control or cohort studies with a low risk of

confounding or bias and a moderate probability that the relationship

is causal

2- Case control or cohort studies with a high risk of confounding or bias

and a significant risk that the relationship is not causal

3 Non-analytic studies, e.g. case reports, case series

4 Expert opinion

Scottish Intercollegiate Guidelines Network, 2011

43

Appendix III: Evidence Tables and Quality Assessment Results De Witte, J. L., Demeyer, C., Vandemaele, E. (2010). Resistive-heating or forced-air warming for the prevention of redistribution hypothermia. Anesthesia &

Analgesia, 110(3), 829-833.

Study

type

Number

of

patients

Patients

Characteristics

Intervention Comparison Length of

follow up

Outcomes measures Effect size

RCT 27 Surgery type

(elective):

Elective

laparoscopic

colorectal surgery

Mean age:

Group0: 59

Group1: 66

Sex(M/F): 18/9

ASA: ≤3

Group 1:

Pre-op forced

air warming

for 30min

Group 0:

Cotton

blanket

Day of surgery Core temperature (C)

Skin temperature (C)

Mean skin temp lower in control

group (p<0.05)

Mean core temp of intervention group

higher than control group at 5min,

40min, 50min (p<0.05)

44

Study identification:

De Witte, J. L., Demeyer, C., Vandemaele, E. (2010). Resistive-heating or forced-air warming for

the prevention of redistribution hypothermia. Anesthesia & Analgesia, 110(3), 829-833.

SECTION 1: INTERNAL VALIDITY

In a well conducted RCT study… In this study this criterion is:

1.1 The study addresses an appropriate and clearly focused

question.


1.2 The assignment of subjects to treatment groups is

randomized Well covered

1.3 An adequate concealment method is used Well covered

1.4 Subjects and investigators are kept ‘blind’ about

treatment allocation


1.5 The treatment and control groups are similar at the start

of the trial Well covered

1.6 The only difference between groups is the treatment

under investigation Well covered

1.7 All relevant outcomes are measured in a standard, valid

and reliable way Well covered

1.8 What percentage of the individuals or clusters recruited

into each treatment arm of the study dropped out before

the study was completed?

Zero

1.9 All the subjects are analysed in the groups to which

they were randomly allocated (often referred to as

intention to treat analysis)

Well covered

1.10 Where the study is carried out at more than one site,

results are comparable for all sites Not addressed

SECTION 2: OVERALL ASSESSMENT OF THE STUDY

2.1 How well was the study done to minimise bias?

Code ++, +, or

+

2.2 Taking into account clinical considerations, your

evaluation of the methodology used, and the statistical

power of the study, are you certain that the overall

effect is due to the study intervention?

Yes

2.3 Are the results of this study directly applicable to the

patient group targeted by this guideline?

Yes

45

Horn, E. P., Bein, B., Bohm, R., Steinfath, M., Sahili, N., & Hocker, J. (2012). The effect of short time periods of pre-operative warming in the prevention of

peri-operative hypothermia. Anaesthsia, 76, 612-217.

Study

type

Number

of

patients

Patients

Characteristics

Intervention Comparison Length of follow

up


RCT 200 Surgery type

(elective):

Laparoscopic

Breast

Orthopedic

Others

Mean age:

Group 0: 49

Group 1: 55

Group 2: 52

Group 3: 54

Sex(M/F): 64/136

ASA:<3

Active

pre-operative

forced-air warming

for :

Group 1: 10 min

Group 2: 20 min

Group 3: 30 min

Group 0:

Passive

insulation

No active

warming

30min before

induction to

60min

postoperatively

Core temperature (C)

(tympanic membrane)

Grades of shivering

Change of core temp in

intervention groups

(p<0.01)

Decrease post-op shivering

(p<0.02)

46

Study identification

Horn, E. P., Bein, B., Bohm, R., Steinfath, M., Sahili, N., & Hocker, J. (2012). The efect of short time

periods of pre-operative warming in the prevention of peri-operative hypothermia. Anaesthsia, 76,

612-217.



1.1 The study addresses an appropriate and clearly focused

question.



randomised Well covered


1.4 Subjects and investigators are kept ‘blind’ about treatment

allocation


1.5 The treatment and control groups are similar at the start of

the trial Well covered

1.6 The only difference between groups is the treatment under

investigation Well covered

1.7 All relevant outcomes are measured in a standard, valid and

reliable way Well covered

1.8 What percentage of the individuals or clusters recruited into

each treatment arm of the study dropped out before the study

was completed?

Zero

1.9 All the subjects are analysed in the groups to which they

were randomly allocated (often referred to as intention to

treat analysis)

Well covered

1.10 Where the study is carried out at more than one site, results

are comparable for all sites

Not addressed



Code ++, +, or

++

2.2 Taking into account clinical considerations, your evaluation

of the methodology used, and the statistical power of the

study, are you certain that the overall effect is due to the

study intervention?

Yes

2.3 Are the results of this study directly applicable to the patient

group targeted by this guideline?

Yes

47

Kim, J. Y., Shinn, H., Oh, Y. J., Hong, Y. W., Kwak, H. J., Kwak, Y. L. (2006). The efect of skin surface warming during anesthesia preparation period of off-pump

coronary artery bypass surgery. European Journal of Cardio-thoracic Surgery, 29, 343-347.

Study

type

Number

of

patients

Patients

Characteristics


follow up


RCT 40 Surgery type:

Off pump coronary

artery bypass

surgery

Mean age:

Group0: 61.3

Group1: 64.1

Sex(M/F): 30/10

Group 1:

Pre-op forced

air warming

and

Warming

mattress

Group 0:

2 cotton

blankets

Warming

mattress

On arrival in

the OR to

90min after

induction



Core temp higher in pre-warm

group (p<0.05)

48


Kim, J. Y., Shinn, H., Oh, Y. J., Hong, Y. W., Kwak, H. J., Kwak, Y. L. (2006). The efect of

skin surface warming during anesthesia preparation period of off-pump coronary artery

bypass surgery. European Journal of Cardio-thoracic Surgery, 29, 343-347.



1.1 The study addresses an appropriate and clearly

focused question. Well covered


randomized Well covered





1.5 The treatment and control groups are similar at the

start of the trial Well covered



1.7 All relevant outcomes are measured in a standard,

valid and reliable way Well covered

1.8 What percentage of the individuals or clusters

recruited into each treatment arm of the study dropped

out before the study was completed?

Zero




Well covered





Code ++, +, or

+





Yes



Yes

49

Melling, A. C., Ali, B., Scott, E. M., & Leaper D. J. (2001). Effects of preoperative warming on the incidence of wound infection after clean surgery: a

randomized controlled trial. The Lancet, 358, 876-880.

Study

type

Number

of

patients

Patients

Characteristics

Intervention Comparison Length of follow

up


RCT 421 Surgery type

(elective):

Breast

Varicose vein

Hernia

Mean age:

Group 0: 50.4

Group 1: 49.7

Group 2: 50

Sex(M/F): 174/242

Group 1:

Pre-op forced air

warming for

30min

Group 2:

Pre-op forced air

warming for

30min only on

planned wound

area

Group 0:

Usual

preoperative

care

On arrival in the

OR to 6 weeks

post-op


Sign of wound

infection

ASEPSIS wound

scoring system

Core temp increased in group 1

(p<0.001)

Core temp increased in group 0

(p=0.028)

Lower wound infection rate in

group 1 & 2 (p=0.001)

ASEPSIS lower in group 1 & 2

(p=0.007)

50


Melling, A. C., Ali, B., Scott, E. M., & Leaper D. J. (2001). Effects of preoperative

warming on the incidence of wound infection after clean surgery: a randomized controlled

trial. The Lancet, 358, 876-880.




focused question.

















Control group: 1%

Treatment group: 4%




Well covered





Code ++, +, or

++





Yes



Yes

51

Ng, S. F., Oo, C. S., Loh, K. H., Lim, P. Y., Chan, Y. H., Ong, B. C. (2003). A comparative study of three warming interventions to determine the most

effective in maintaining perioperative normothermia. Anesth Analg, 96, 171-176.

Study

type

Number of

patients

Patients

Characteristics


follow up


RCT 300 Surgery type:

Elective unilateral

total knee

replacement

ASA: <3

Group 1:

Reflective

blanket

Group 2:

Forced-air

warming

blanket

Group 0:

2 cotton

blankets

On arrival in

OR 45min

before surgery

to discharge

from the

recovery room

Tympanic temperature (C)

• Group 2 more effective in

maintaining normal

temperature from induction

room to recovery room

compared with Group 0

(p<0.001)

• Group 2 more effective in

maintaining normal

temperature from induction

room to recovery room

compared with Group 1

(p<0.001)

52


Ng, S. F., Oo, C. S., Loh, K. H., Lim, P. Y., Chan, Y. H., Ong, B. C. (2003). A comparative

study of three warming interventions to determine the most effective in maintaining

perioperative normothermia. Anesth Analg, 96, 171-176.




focused question.

















Zero




Well covered





Code ++, +, or

++





Yes



Yes

53

Vanni, S. M., Braz, J. R., Modolo, N. S., Amorim, R. B., Rodrigues, G. R. Jr. (2003). Preoprative combined with intraoperative skin-surface warming avoids

hypothermia caused by general anesthesia and surgery. Journal of Clinical Anesthesia, 15, 119-125.

Study

type

Number

of

patients

Patients

Characteristics


follow up


RCT 30 Surgery type

(elective):

Abdominal

surgery

Mean age:

Group 0: 44

Group 1: 39

Group 2: 34

Sex: all female

ASA: <3

Group 1:

pre-op +

intra-op forced

air warming

Group 2:

intra-op forced

air warming

Group 0:

No special

precautions

were taken

to avoid

hypothermi

a

On arrival in

OR to leaving

OR



Shivering (absent,

mild, severe)

Group 1, skin temp increased at the

end of anesthesia (p<0.05)

Group2, core temp increased at the

end of anesthesia (p<0.05)

Frequency of hypothermia at

arrival in recovery is lower in

group 1 & 2 (p<0.001)

54


Vanni, S. M., Braz, J. R., Modolo, N. S., Amorim, R. B., Rodrigues, G. R. Jr. (2003).

Preoprative combined with intraoperative skin-surface warming avoids hypothermia caused

by general anesthesia and surgery. Journal of Clinical Anesthesia, 15, 119-125..




focused question.

















Zero




Well covered





Code ++, +, or

+





Yes



Yes

55

Appendix IV: Summary of Level of Evidence Bibliographic citation Study type Level of evidence

De Wittee et al. (2010) RCT 1+

Horn et al. (2012) RCT 1+

Kim et al. (2006) RCT 1+

Melling et al. (2001) RCT 1+

Ng et al. (2003) RCT 1+

Vanni et al. (2003) RCT 1+

56

Appendix V: Summary of Quality Assessment Internal validity De Wittee et al. Horn et al. Kim et al. Melling et al. Ng et al. Vanni et al.


focused question. Adequately

addressed

Adequately

addressed Well covered

Adequately

addressed

Adequately

addressed

Adequately

addressed

1.2 The assignment of subjects to treatment groups

is randomised Well covered Well covered Well covered Well covered

Well covered Well covered

1.3 An adequate concealment method is used Well covered Well covered Well covered Well covered




Adequately

addressed

Adequately

addressed

Adequately

addressed

Adequately

addressed

Adequately

addressed

Adequately

addressed

1.5 The treatment and control groups are similar at

the start of the trial Well covered Well covered Well covered Well covered


1.6 The only difference between groups is the

treatment under investigation Well covered Well covered Well covered Well covered


1.7 All relevant outcomes are measured in a

standard, valid and reliable way Well covered Well covered Well covered Well covered



recruited into each treatment arm of the study

dropped out before the study was completed?

0 0 0 Control: 1%

Treatment: 4%

0 0

1.9 All the subjects are analysed in the groups to

which they were randomly allocated (often

referred to as intention to treat analysis)

Well covered Well covered Well covered Well covered


1.10 Where the study is carried out at more than

one site, results are comparable for all sites Not addressed

Not addressed Not addressed Not addressed Not addressed Not addressed

How well was the study done to minimise bias? + ++ + ++ ++ +

57

Appendix VI: Grade of Recommendations Grade of Recommendations Note: The grade of recommendation relates to the strength of the evidence on which the recommendation is based. It

does not reflect the clinical importance of the recommendation.

A At least one meta-analysis, systematic review, or RCT rated as 1++, and directly applicable to the target population; or

A body of evidence consisting principally of studies rated as 1+, directly applicable to the target population, and

demonstrating overall consistency of results

B A body of evidence including studies rated as 2++, directly applicable to the target population, and demonstrating

overall consistency of results; or

Extrapolated evidence from studies rated as 1++ or 1+

C A body of evidence including studies rated as 2+, directly applicable to the target population and demonstrating overall

consistency of results; or

Extrapolated evidence from studies rated as 2++

D Evidence level 3 or 4; or

Extrapolated evidence from studies rated as 2+

E Recommended best practice based on clinical experience of the guideline development group

Scottish Intercollegiate Guidelines Network, 2011

58

Appendix VII: Evaluation Form of Satisfaction Levels of

Frontline Staffs

Dear Colleagues,

Thank you for your participation in conducting preoperative active warming.

Your comments are valuable to us in improving quality of patient care.

Please comment on the follow statements by putting a in the appropriate box.

1=strongly disagree 2=disagree 3=neutral 4=agree 5=strongly agree

Satisfaction Level

1 2 3 4 5

1 You are clear about the aim of the innovation

2 You are able to cope with the innovation workload.

3 Patients can benefit from the innovation.

4 You are satisfied with the innovation.

5 The innovation enhanced your job satisfaction.

1. What are the difficulties encountered during implementation of the

innovation?

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________

2. What are the advantages of the innovation?

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________

3. Other comments:

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________

59

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