preoperative assessment yr 4 anaesthesia clerkship
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Preoperative assessment Yr 4 Anaesthesia Clerkship. Dr Patricia Chalmers 2010-2011. O bjectives of preoperative assessment Fasting status The airway Volume status Systemic effects of anaesthetic agents Allergies and genetic considerations Risk Stratification - PowerPoint PPT PresentationTRANSCRIPT
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Preoperative assessmentYr 4 Anaesthesia Clerkship
Dr Patricia Chalmers
2010-2011
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•Objectives of preoperative assessment•Fasting status•The airway•Volume status•Systemic effects of anaesthetic agents•Allergies and genetic considerations•Risk Stratification•Respiratory and cardiovascular assessment•Patient sketches•Overview of history and examination
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Preoperative Assessment
Objectives• To deliver good quality care• To establish doctor-patient rapport• To establish a clinical picture of the patient• To identify risk factors• To draw up a management plan• To optimise any concurrent medical conditions• To minimise the occurrence of critical incidents
in the perioperative period
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Clinical Picture
Full medical history and physical examination
Points of specific relevance to anaesthesia:
RISK STRATIFICATION
General health of patient and functional capacity
Surgical procedure
Concurrent medical conditions and medication
History of reactions and allergies to anesthesia THE AIRWAY
Fasting Status Volume Status
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FASTING STATUS
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FASTING STATUS
6 hrs solids
4hrs liquids
(2hrs clear fluid /water)
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The Full StomachMechanisms
• Reflux
• Delayed gastric emptying
• Raised abdominal pressure
• Pharyngeal and laryngeal incompetence
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The Full StomachClinical conditions
GORDOpioidsAutonomic neuropathy: diabetesPregnancyIntestinal obstructionTraumaHead InjuryMyopathies/ bulbar palsy
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Preoperative measures to reduce risk of aspiration
• Proton pump inhibitors
• H2 blockers
• Metoclopramide
• 0.3M Sodium citrate 30ml
• Nasogastric tube where applicable
(Induction of anaesthesia: RSI)
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THE AIRWAY
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THE AIRWAY
• Examination Facial swelling• Mouth opening• Dentition• Macroglossia• MALLAMPATI GRADE• Thyromental distance• Neck shape and mobility
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Mallampati Grades
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Mallampati Grades
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Volume Status
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VOLUME STATUS
Assess preoperative deficit
a.Clinical picture
b.Formula
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Volume Status
TBW 70kg male
55-60% Body weight 45l
Intracellular 30 L
Extracellular 15 L interstitial 12L intravascular 3L
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Clinical DehydrationBody wt loss S&S5% thirst, dry mouth
5-10% reduced peripheral perfusion, reduced skin turgor, oliguria, postural hypotension, tachycardia reduced CVP, lassitude,
10-15% inc RR, hypotension, anuria, delirium, coma
>15% Life threatening
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Formula
• 4mls/kg/hr for first 10 kg body weight
• 2mls/kg/hr for the next 20kg body wt
• 1ml/g /hr for every other kg body weight
• Adult 2mls/kg/hr
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Fluid replacement
• Replace existing deficit: 50% deficit in 1st hr, 25% in 2nd hr, 25% in 3rd hr• Maintain fluid balance 2mls/kg/hr
• Deficit: fasting/ burns/GI losses
• Consider ongoing losses
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Effects of anesthetic agents and drugs
• Respiratory depression, impaired lung function →, HYPOXIA
• Depressed myocardial function →HYPOTENSION arrthymias,
• Impaired delivery of O2 to the tissues
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Effects of anaesthetic agents on respiratory function
• Depression of RC
• Diminished muscle tone
• Reduced lung compliance(loss of elastic recoil)→ ↓TLC ↓TV ↓FRC and ↑Closing volume
• Atelectasis
• ↑Dead space(respiratory circuit)
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Increased work of breathingIncreased ventilation /perfusion mismatch
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Effects of anaesthetic agents on cardiovascular functionReduced contractility
Reduced stroke volume
Vasodilatation
Hypotension
Risk of reduced coronary perfusperfusion
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Effects of anesthetic agents and drugs (contd)
• Metabolism and elimination of drugs dependent on hepatic and renal function
• Muscle relaxation and paralysis
• Stress Response
• Adverse effect on co-morbidities
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Perioperative Clinical Risks
• Respiratory depression
• Cardiac ischaemia
• Arrthymias
• Myocardial infarction
• Stroke
• Renal impairment
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Risk Stratification
• ASA grades
• Surgical procedure
• Age
• BMI
• Elective v Emergency
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ASA GRADING
1. Healthy Patient
2.Mild systemic disease with no impact on life
3.Systemic disease with limiting factors
4. Systemic disease with a constant threat to life
5. Moribund patient
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Grading of General Surgical Procedures
1. Minor eg skin lesion
2. Intermediate eg inguinal hernia arthroscopy
3. Major eg hysterectomy,
4. Major+ eg colonic resection, radical neck dissection,
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Preoperative assessment
• Is there any evidence of active disease?
• Are there any clinical risk factors?
• What is the patient’s functional capacity?
• What maintenance medication is the patient on?
• How can we optimise the patient’s clinical condition?
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Patient sketch 1
• 53 year old female for ligation of varicose veins• She has a history of asthma and neglects her
medication• o/e anxious • RR 24/min• widespread rhonchi• PEF 65% • Other systems unremarkable
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Patient sketch 2
• 64 yr old male with intestinal obstruction for a laparatomy
• History of COPD previous heavy smoker • Gets breathless walking uphill or fast on
level ground • Coughing purulent sputum• FEV1 75%• On combined therapy with beta 2 agonist
and anticholinergic
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Preoperative measures to improve lung function
• Stop smoking
• Chest physio
• Bronchodilators
• Antibiotics
• Steroids
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Patient sketch 3
• 55yr old female for hysterectomy
• Diabetic on twice daily insulin
• BP 140/90
• What investigations and management
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22 kg child for removal of plaster cast
Fasting from midnight In theatre at 10.00amWhat is her fluid deficit?
Patient sketch 4
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84 yr old female with a fractured neck of femurTripped in bathroom lives alone and lay there for 20 hours She is thin stature, lives on tea, toast and cakeHistory of CCF On diuretics
? Considerations and management
Patient Sketch 5
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Patient Sketch 6
40 yr old male for elective cholecystectomy
Heavy smokerHR 80/min BP 200/115Hb 14.0 gm/dlUrea 8 mmols/lCreatinine 140mmols/l
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40 yr old male for cholecystectomyHR 80/min regBP 150/95Hb 12.8 gm/dl Urea 5.8 mmols/lCreatinine 115 µmols/l Na 130mmols/lK 4.5mmols/l
Patient sketch 7
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Patient sketch 8
• 44 year old female for mastectomy and reconstruction
• 5 year history of angina, becoming more frequent and increasing in severity over past 6 months
• Both parents died from myocardial infarction• Coronary angiogram 2yrs ago no vessel disease • Ca antagonists,glyceryl trinitrate, isosorbide
dinitrate, verapamil,
Risk Factors Investigations Management
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Perioperative Cardiac Risk in relation to noncardiac surgery
• Hi >5%: Vascular Aortic and peripheral vascular surgery
• Intermediate 1-5%: intraperitoneal, intrathoracic, carotid endarterectomy, head and neck , orthopaedic, prostrate,
• Lo risk <1%: endoscopic, superficial, cataract, breast, day stay procedures
ACC/AHA 2007 guidelines
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Preoperative measures to improve cardiovascular status
• Continue maintenance meds• Control heart failure• Stabilise arrthymias• Stabilise uncontrolled hypertension• Lo dose short acting beta-blockers for IHD if Hi
or intermediate risk • Statins considered• Prophylactic antibiotics for valvular
disease/prosthesis
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Systematic enquiry • RS
• CVS• GIT HH GORD PUD
• Renal system
• Hepatic system• Endocrine diabetes thyroid
• Bone joint and ct disorders RA• Haemotological anaemia coagulopathy DVT
• Neurological and muscular epilepsy
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Systematic Enquiry (contd)
• Medications Diuretics, Steroids, Diabetes, Epilepsy, Anticoagulants etc
• Allergies
• Social history Smoking, Alcohol
• Previous Anaesthetic history PONV
• FH genetic disorder SUX apnoea MH
• Fasting status 6hrs (2hrs clear fluids)
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Age ASA Surgery Spec cons
FBC Elderly 2-5 2-4 Pallor
hge
U&E’s Elderly 3-5 3-4 Dehydration
G&H/ X-match
3-4 Poly-trauma
ECG M>40,
F>50
CVS 2
RS 3
2
CXR CVS 2
RS 3
Pneumonia
Investigations
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INVESTIGATIONS– FBC– U&E’S
Where indicated– Group & Hold/X-match– ECG– CXR– Glucose– Coag screen (spinal, epidural)– BGA– Cardiac ultrasound– RFT’s
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Key Points (1)History: Full systemic history
• Medications for maintenance
• Allergies
• Add previous anaesthetic history PONV• FH Sux apnoea, MALIGNANT HYPERTHERMIA
FASTING status
Anaesthetic Risk Stratification
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Key Points (2)Examination: Full systemic examination
Add THE AIRWAY
Consider Volume status G&H/X-match
Obtain Consent
Discuss pain management ---reassure
Continue maintenance meds
Draw up Anaesthetic Plan
Bear in mind effects of anaesthesia on patient and effects of co-morbidities on the anaesthetic technique
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Recommended Reading
Neville Robinson, George Hall“How to Survive in Anaesthesia”
BMJ Books 2nd Ed 2002