Preoperative Assessment &Premedication

Craigavon Area Hospital CT1 Education Series (Intro)

Dr. Andrew Ferguson

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

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

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

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

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

NICE CG3 (2003)

Dr. Andrew Ferguson

Dr. Andrew Ferguson

Dr. Andrew Ferguson

Dr. Andrew Ferguson

Dr. Andrew Ferguson

Dr. Andrew Ferguson

Dr. Andrew Ferguson

Pre-op Testing Schema Example

Dr. Andrew Ferguson

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

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

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

Dr. Andrew Ferguson

Physical Examination

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

Dr. Andrew Ferguson

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

Mallampati & Samsoon Score

Dr. Andrew Ferguson

Mallampati Class 1 !!!!

Dr. Andrew Ferguson

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

Cormack & Lehane Score

1 2

3 4

Dr. Andrew Ferguson

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

Evaluating Cardiac Disease

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

Dr. Andrew Ferguson

CVS evaluation for non-cardiac surgery

Dr. Andrew Ferguson

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

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

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

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

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

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

Pulmonary Hypertension

• High risk• ECG & echo• Disease severity indicators

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

Dr. Andrew Ferguson

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

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

Periop Medication Management

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

• What to keep• What else to give

Dr. Andrew Ferguson

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

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

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

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