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Preoperative Assessment (Intro)

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Preoperative Assessment & Premedication Craigavon Area Hospital CT1 Education Series (Intro) Dr. Andrew Ferguson
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Page 1: Preoperative Assessment (Intro)

Preoperative Assessment &Premedication

Craigavon Area Hospital CT1 Education Series (Intro)

Dr. Andrew Ferguson

Page 2: Preoperative Assessment (Intro)

Overview• Setting the scene• Preoperative testing• Components of the preoperative visit

– History & Physical Examination [emphasis on Airway]• Introduction to organ-specific issues

– Evaluating Cardiovascular Disease– Evaluating Respiratory Disease

• Perioperative Medication Management– Stopping patient medications….or not– Premedication

• Fasting

Dr. Andrew Ferguson

Page 3: Preoperative Assessment (Intro)

Pre-op Assessment - AAGBI Guidance (2001)

• The anaesthetist– is uniquely qualified to assess risk– is responsible for deciding fitness for anaesthesia– must see all patients before operation

• The aim of assessment is to improve outcome• Blanket pre-op investigations waste resources & time

Dr. Andrew Ferguson

Page 4: Preoperative Assessment (Intro)

Goals of assessment

• Screen for and manage co-morbid disease• To assess and minimise risks of anaesthesia• To identify need for specialised techniques• To identify need for advanced post-op care• To educate about anaesthesia• To obtain informed consent• To avoid unnecessary delays/cancellations• To motivate patients to improve pre-op

Dr. Andrew Ferguson

Page 5: Preoperative Assessment (Intro)

Preoperative Assessment Systems

• Screening questionnaire (F2F, online, PC)• Preoperative assessment clinic

• nurse led• consultant supported• coordinates availability of information• coordinates preoperative investigations

• Preoperative visit

Dr. Andrew Ferguson

Page 6: Preoperative Assessment (Intro)

Pre-operative Testing

• Only when indicated– from history/examination, or– based on surgical plan

• ECG for example• Abnormal in 62% of patients with known cardiac disease• Abnormal in 44% of patients with strong IHD risk factors• Abnormal in 7% of over-50s with no risk factors• Abnormal in 3% of 50-70 year olds with no risk factors• New Q waves or arrhythmias < 2%• Limited use as predictor of outcome - may alter plan

Dr. Andrew Ferguson

Page 7: Preoperative Assessment (Intro)

NICE CG3 (2003)

Dr. Andrew Ferguson

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Dr. Andrew Ferguson

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Dr. Andrew Ferguson

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Dr. Andrew Ferguson

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Dr. Andrew Ferguson

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Dr. Andrew Ferguson

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Dr. Andrew Ferguson

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Pre-op Testing Schema Example

Dr. Andrew Ferguson

Page 15: Preoperative Assessment (Intro)

ASA Minimum Pre-op Visit Components

• Medical, anaesthesia and medication history• Appropriate physical examination• Review of diagnostic data (ECG, labs, x-rays)• Assignment of ASA physical status• Formulation and discussion of anesthesia plan

Dr. Andrew Ferguson

Page 16: Preoperative Assessment (Intro)

The ASA Physical Status Classification

ASA 1 Normal healthy patient MortalityASA 2 Mild systemic disease - no impact on daily life 0.1%ASA 3 Severe systemic disease - significant impact on daily life 0.2%ASA 4 Severe systemic disease that is a constant threat to life 1.8%ASA 5 Moribund, not expected to survive without the

operation 7.8%

ASA 6 Declared brain-dead patient - organ donor 9.4%E Emergency surgery

Dr. Andrew Ferguson

Page 17: Preoperative Assessment (Intro)

History

• Medical problems (current & past)• Previous anaesthesia & related problems• Family anaesthesia history• Allergies and drug intolerances• Medications, alcohol & tobacco• Review of systems (include snoring and fatigue)• Exercise tolerance and physical activity level

Dr. Andrew Ferguson

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Dr. Andrew Ferguson

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Physical Examination

• Minimum requirements– Airway– Heart & lungs– Vital signs including O2 saturation– Height & weight (BMI)

Dr. Andrew Ferguson

Page 20: Preoperative Assessment (Intro)

Airway Examination• Teeth and bite• Ability to protrude lower incisors beyond upper• Mouth opening (inter-incisor distance)• Mallampati score• Facial hair• Thyromental distance• Length & thickness of neck• Range of motion of head & neck

Dr. Andrew Ferguson

Page 21: Preoperative Assessment (Intro)

Mallampati & Samsoon Score

Dr. Andrew Ferguson

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Mallampati Class 1 !!!!

Dr. Andrew Ferguson

Page 23: Preoperative Assessment (Intro)

Independent Predictors of Difficult Mask Ventilation and Intubation

Difficult Mask Ventilation P-valueBeard 0.0001History of snoring 0.001BMI > 30 0.0001Mallampati III or IV 0.001Age > 50 0.01Severely limited jaw protrusion 0.03Difficult Mask Ventilation & IntubationSeverely limited jaw protrusion 0.0001Thick neck/mass 0.02History of sleep apnoea 0.04BMI > 30 0.05History of snoring 0.05Dr. Andrew Ferguson

Page 24: Preoperative Assessment (Intro)

Cormack & Lehane Score

1 2

3 4

Dr. Andrew Ferguson

Page 25: Preoperative Assessment (Intro)

Physical Examination - Risk Factors for Difficult IntubationRisk Factor Detail Level of RiskWeight < 90 kg 0

90-110 kg 1

> 110 kg 2

Head & Neck Movement > 90 o 0

Approx 90 o 1

< 90 o 2

Jaw movement

IG = Interincisor gapSlux = mandibular subluxation

IG > 5 cm or Slux > 0 0

IG < 5 cm or Slux = 0 1

IG < 5 cm or Slux < 0 2

Receding Mandible Normal 0

Moderate 1

Severe 2

Protruding maxillary teeth Normal 0

Moderate 1

Severe 2Dr. Andrew Ferguson

Page 26: Preoperative Assessment (Intro)

Evaluating Cardiac Disease

• Ischaemic heart disease• Heart failure• Arrhythmia• Abnormal ECG• Undiagnosed murmur• Pacemaker or IACD

Dr. Andrew Ferguson

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CVS evaluation for non-cardiac surgery

Dr. Andrew Ferguson

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NYHA Functional ClassClass I No limitation of physical activity; ordinary activity does not cause fatigue,

palpitations or syncope

Class II Slight limitation of physical activity; ordinary activity results in fatigue, palpitations or syncope

Class III Marked limitation of physical activity; less than ordinary activity results in fatigue, palpitations or syncope; comfortable at rest

Class IV Inability to do any physical activity without discomfort; symptoms at rest

Dr. Andrew Ferguson

Page 29: Preoperative Assessment (Intro)

Metabolic Equivalents (METs)

Activity METS min METS max

Cycling 5 mph 2 3

Cycling 10 mph 5 6

Cycling 13 mph 8 9

Ballroom Dancing 4 5

Swimming 8 10

Tennis 4 9

Walking 1 mph 1 2

Walking 2 mph 2 3

Walking 3 mph 3 3.5

Walking 4 mph 5 6

Activity METS min METS max

Bed making 2 6

Carrying heavy bags 5 7

Cleaning windows 3 4

Dressing 2 3

General housework 3 4

Grocery shopping 2 4

Painting/decorating 4 5

Sexual intercourse 3 5

Showering 3 4

Vacuuming 3 3.5

Walking up stairs 4 7

1 MET = 3.5 ml O2 utilisation/kg/min

Tolerance < 4 METs = higher risk

Dr. Andrew Ferguson

Page 30: Preoperative Assessment (Intro)

Arrhythmias/ECG abnormalities

• Further work-up or therapy needed– New onset AF– Symptomatic bradycardia– High-grade heart block (2nd or 3rd degree)– Uncontrolled AF– VT– Prolonged QT– New LBBB– RBBB with right precordial ST elevation (Brugada)

Dr. Andrew Ferguson

Page 31: Preoperative Assessment (Intro)

Pacemakers/IACD• Determine type• Determine features• Pacemaker check/interrogation pre-op• Disable rate-adaptive mechanisms• Disable anti-tachyarrhythmia functions• Magnet not recommended for modern devices

Dr. Andrew Ferguson

Page 32: Preoperative Assessment (Intro)

Evaluating Respiratory DiseaseEstablished Risk Factors for Pulmonary Complications

Urea > 10.7 mmol/L (30 mg/dL) [OR 2.29]Partially or fully dependent [OR 1.92]Age > 70 [OR 1.91]COPD [OR 1.81]Neck, thoracic, upper abdominal, aortic or neurological surgeryProlonged procedures (> 2 hours)Emergency surgery [OR 3.12]Hypoalbuminaemia (< 30 g/L) [OR 2.53]Exercise tolerance < 1 flight of stairs / 100 yardsBMI > 30

Dr. Andrew Ferguson

Page 33: Preoperative Assessment (Intro)

VAMC Respiratory Failure Risk Index [Arozullah Ann Surg 2000;232:242-53]

Preoperative Predictor Point ValueAbdominal aortic aneurysm surgery 27

Thoracic surgery 21

Neurosurgery, upper abdominal, peripheral vascular surgery 14

Neck surgery 11

Emergency surgery 11

Albumin < 30 g/L 9

Urea > 10.7 mmol/L (30 mg/dL) 8

Partially or fully dependent status 7

COPD 6

Age > 70 6

Age 60-69 4

Class Point total N (%) Predicted PRF Actual PRF Phase 1 Actual PRF Phase 21 < 10 39,567 (48%) 0.5% 0.5% 0.5%

2 11-19 18,809 (23%) 2.2% 2.1% 1.8%

3 20-27 13,865 (17%) 5% 5.3% 4.2%

4 28-40 7,976 (10%) 11.6% 11.9% 10.1%

5 >40 1,502 (2%) 30.5% 30.9% 26.6%Dr. Andrew Ferguson

Page 34: Preoperative Assessment (Intro)

Pulmonary Hypertension

• High risk• ECG & echo• Disease severity indicators

• SOB at rest• Metabolic acidosis• Hypoxaemia• Right heart failure• Syncope

Dr. Andrew Ferguson

Page 35: Preoperative Assessment (Intro)

URTI & anaesthesia

• Mild symptoms - can usually proceed– huge inconvenience to patient if cancelled

• Severe symptoms or underlying disease– postpone

• Intermediate severity - ?• ? risk of increased bronchial reactivity

Dr. Andrew Ferguson

Page 36: Preoperative Assessment (Intro)

Sleep-disordered Breathing• 24% of middle aged men (< 15% diagnosed!)• OSA - complete obstruction for 10s +• OH (obstructive hypopnoea) > 4% drop in sats• CVS disease common• Berlin Questionnaire

• Snoring• Daytime sleepiness• Hypertension• Obesity

2 or more = high risk for OSA

Dr. Andrew Ferguson

Page 37: Preoperative Assessment (Intro)

Periop Medication Management

• What to stop (suggestions! - discuss with cons)

• What to keep• What else to give

Dr. Andrew Ferguson

Page 38: Preoperative Assessment (Intro)

Hold on day of surgery

• Diuretics• unless thiazide for hypertension• unless severe heart failure

• Insulin & OHA - see hospital diabetic protocol• Vitamins & iron• ACEI’s or ARB’s (individual choice)

• depends on procedure/risk of hypotension

• Hold sildenafil/tadalafil from night before

Dr. Andrew Ferguson

Page 39: Preoperative Assessment (Intro)

Preop Medicines ManagementStop 48 hours pre-opNSAIDsStop 4 days pre-opWarfarin (convert to enoxaparin)Stop 7 days pre-opClopidogrelAspirin 75 mg usually continued (check with consultant)Herbal remediesHRT

Dr. Andrew Ferguson

Page 40: Preoperative Assessment (Intro)

Premedication• Alleviate anxiety/sedation/amnesia

• e.g. temazepam 10-20 mg, midazolam pre-induction

• Reduce risk of reflux• e.g. ranitidine/lansoprazole/citrate/metoclopramide

• Manage pain• e.g. paracetamol, gabapentin, topical LA

• Control perioperative risk• e.g. blockade, -2 agonists

• Dry secretions• e.g. glycopyrollate

• Decrease anaesthetic requirements• e.g. clonidine

Dr. Andrew Ferguson

Page 41: Preoperative Assessment (Intro)

Fasting GuidelinesTime before anaesthesia Food or fluid intake

Up to 8 hours Unrestricted

Up to 6 hours Light meal

Up to 4 hours Breast milk

Up to 2 hours Clear liquids only (no solids, no fat)

2 hours pre-anaesthesia Nothing permitted

Dr. Andrew Ferguson


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