Investigation into Significant Anesthesia

Adverse Events during the Post-Op Period

Research by:Ryan Dietz RNAIStephen Both RNAI Gonzaga UniversityProvidence Sacred Heart Medical

CenterMarch 20, 2014

MethodologyRetrospective Chart Review

At PHSMCPopulations

1. Strokes, cardiopulmonary arrests (CPAs), and deaths

(within 30 days of an anesthetic)2. PACU physiologic instability

Hemodynamic problems Bleeding Oxygenation issues

Study numbers:Charts from 2013

PACU physiologic instability 29 Strokes 13 CPAs 16 Mortality 41 99

Number of Patients Investigated

(1 mo.)(6mo.)(6mo.)(6mo.)

~Inpatient Research Study~

Hypertension35%

Resp De-pression

30%

Hypotension20%

Arrhythmia 5%

Bleeding5%

Hyper-glycemia

5%

Physiologic Instability PACU (n=29) PSHMC

Hypotension Dynamics

ASA I ASA II ASA III ASA IV ASA V0%

10%

20%

30%

40%

50%

60%

70%ASA Distribution (n=29)

PSHMC

Physiologic Instability (PACU)

Perc

en

t of

Pati

en

ts

68%16%

16%

ASA II Physiologic Instability Causes

PACU (n=13) PSHMC Hypotension

Resp de-pression

Bleeding

44% of this group received Spinal Anesthesia

62%

31%

8%

Stroke Etiology at PSHMC (n=13) PSHMC

Embolic

Ischemic

Hemorrhagic

Cardiac Vascular Ortho Neuro0%

20%

40%

60%

80%

100%

120%

40%50%

100%

0%

60%

25%

0%

100%

0%

25%

0% 0%

Surgery Type with Cor-responding Type of

Stroke (n=13) PSHMC

EmbolicIschemicHemorrhagic

Surgery Type

Perc

ent

of

Surg

ery

Type

Determinants of Cerebral Blood Flow

Two Determinants of cerebral blood flow:1. Cerebral Vascular Resistance

PaCO2 PaO2 Metabolism

2. Cerebral Perfusion Pressure (CPP) Blood Pressure ICP

1 2 3 4 5 6 7 8 9 10 11 12 130

20

40

60

80

100

120

140

160

180

Stroke: Systolic Comparison SAU vs Entrap (n=13) PSHMC

SAU SBP

Intraop SBP

Patients that Experienced a Stroke

BP

Systo

lic

EMBOLIC STROKES

PaCO2

39.4-42.6

44.2-49.6

28.8-33.2

J. of Cerebral Blood Flow, (2003) : 23 (6). 665-670 [15]

Detrimental Effect of Hypocapnia

Hypocapnia[1,2,3,8,9]

Directly neurotoxic↑ neuronal excitability

while ↓ cerebral O2 supply

↓ V/Q matchingCauses lung injury via inflammation activation

Increase risk of infection

Undermines respiratory drive postop

↓myocardial O2 supply ST depression syndrome

↓ SvO2 Prolongs wakeups↑Pain in postop

54%

23%

15% 8%

etCO2 Values Among Stroke Cases (n=13)

PSHMC

25-30

30-35

35-40

40-45

Summary of Findings

1. Hypertension was the #1 cause of physiologic instability in the PACU

2. 44% of ASA II patients that experienced hypotension also received spinals

3. 54% of patients that experienced strokes during the post op period had etCO2 levels maintained between 25-30 mmHg

Hypertension RecommendationsClinical Situation Drug of Choice

Pain Analgesic

Hypertension without cardiac complications

HydralazinePhentolamineNifedipineNicardipine

Severe acute hypertension Sodium Nitroprusside

Hypertension plus ischemia Nitroglycerine infusion

Hypertension plus tachycardia and ischemia

Esmolol, bolus or infusion

Hypertension plus heart failure Ace Inhibitor, dobutamine

Hypertension caused by pheochromocytoma

Phentolamine, LabetalolDoxazosin, prazosin, terazocin

Continuing Education in Anaesthesia, Critical Care & Pain. (2004) 4 (5): 139-143 [10] Miller’s Anesthesia (2010) p.1094-1095 [21]

Hypotension

Airway Intact?

Effective ventilation & oxygenation?

Appropriate ECG rate, rhythm, and morphology?

Consider hypovolemia,

administer NS IV Bolus

Consider Other etiologies:1. Surgical complications 7. Medication 2. Bleeding 8. Anaphylaxis3. Residual general 9. Equipment Malfunction4. Sepsis5. Anesthesia 6. Sympathectomy from regional blk

Journal of PeriAnesthesia Nursing. (2002). 17 (3) 159-163. [7]

Hypotension Algorithm

Spinal Hypotension A) Blockade of sympathetic efferents (arterial and venodilation)

B) Potential for cardiac accelerator suppression (T1-T4)

Treatment[5]

1. Crystalloid: (500-1500ml ) pretreatment better than co-treatment

2. Colloid: superior to crystalloid (↑SVR) (30 min half-life) Hespan= $12.04/500ml bag *3. Ephedrine superior to Phenylephrine (caution tachyphylaxis)4. Dopamine short term upon ephedrine tachyphylaxis onset5. Cautious use of phenylephrine in the elderly: with reports of ↓

C.O. and LV dysfunction* Cost at PSHMC /Tony Hill (Materials Management

Manager PSHMC)

Mechanism[5]

Hypercapnia

1. Benign (paCO2≤70) [1]

2. Enhances respiratory drive [9]

3. Protects lung tissues [14]

4. Advance warning of inadequate analgesia and relaxation [1]

5. ↑in PaCO2 by 10mmHG

↑the C.I. by about 10-15% [17]

6. ↓ SVR, ↑SvO2 [17]

7. 3-5% alteration in CBF for every 1 mmHg change in PaCO2 [2]

8. Decrease in infection postop [2,3,34]

9. Avoid hypercapnia and hypocapnia in known cerebral ischemic patients [21]

Mild Respiratory Acidosis (A good Thing?)

Hypercapnia can, and many times will lead to mild respiratory acidosis [14,28]

Respiratory Acidosis is different than metabolic acidosis (slight sympathetic activation) [17]

1. ↑ Inotropy2. ↓ SVR3. ↑ Blood pressure4. ↑ HR

PH of 7.15 is tolerated before buffering agents/ ↑RR are necessary [14,28]

“I’m pretty comfortable with a low pH threshold of 7.17 in the healthy or appropriate respiratory acidosis patient” Dr. Chris Vernon DO (Intensivist PSHMC )

Elevated ICP Recommendations

Hypocapnia:

Should only be utilized in two instances[13]

1. Impending brain herniation2. To increase surgical field of view

Normal goal in head injury or elevated ICP is a PaCO2=35-40 [13]

Hypocapnia is only viable for 20 minutes due to cerebral ischemia [13]

Treating impending herniation with hyperventilation [6,21,30]

Goal of PaCO2=30-32Strictly avoid PaCO2 levels below 25 mm HGNot to be used for >20 minutes

Recommendations: Stroke Group

1. Delay elective surgery at least 6 weeks after stroke [21]

2. Continue anticoagulation for minor surgeries (esp. afib + prior stroke) [25]

3. Continue low dose aspirin in patients under procedures of high risk for bleeding and stroke (Bridge with heparin for pt with afib and Hx of Tia/Stroke) [25]

4. Continue beta blockers and statins preop and restart postop [25]

5. Metoprolol controversial during the case (3-4 fold ↑ in strokes). Esmolol & Labetalol, Bisoprolol better choices [4,19,27]

Recommendations: Stroke Group

6. Regional is only beneficial in orthopedic cases [20,25]

7. Avoid hyperventilation during surgery: theories such as “Inverse steal” and “Robin Hood” actually increase the region at risk for stroke [22,29,33]

8. Recommended goal of PCO2 should be normocapnia (35-45). Avoid hypo and hypercapnia in potential cerebral ischemia cases [24]

9. Hypo-albuminemia is a predictor of stroke risk [12]

10.Maintain glucose 60-150mg/dl [11,16]

ConclusionThe purpose of this research project was to

identify potential themes in patient comorbidities, surgery type, and anesthetic management that may potentially contribute to significant postop complications.

Although we did not uncover any “smoking gun” anesthesia related issues, we highlighted and made recommendations regarding 3 interesting findings. Anesthesia is a journey and we will need to continually re-evaluate the method in which we deliver anesthesia.

QUESTIONS?

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