Preoperative Assessment (Intro)
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Preoperative Assessment &Premedication
Craigavon Area Hospital CT1 Education Series (Intro)
Dr. Andrew Ferguson
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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Mallampati & Samsoon Score
Dr. Andrew Ferguson
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Mallampati Class 1 !!!!
Dr. Andrew Ferguson
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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
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Cormack & Lehane Score
1 2
3 4
Dr. Andrew Ferguson
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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
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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
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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
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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
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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
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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
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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
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Pulmonary Hypertension
• High risk• ECG & echo• Disease severity indicators
• SOB at rest• Metabolic acidosis• Hypoxaemia• Right heart failure• Syncope
Dr. Andrew Ferguson
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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
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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
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Periop Medication Management
• What to stop (suggestions! - discuss with cons)
• What to keep• What else to give
Dr. Andrew Ferguson
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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
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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
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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
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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