Optimising the High Risk Bariatric Patient for Surgery Mr Andrew Jenkinson MS FRCS Consultant Surgeon The London Clinic Quality and Safety Lead University College Hospital London Chairman Bariatric Development The London Clinic
Worldwide Prevalence of Obesity Worldwide Obesity League Table
Conditions Associated with Obesity Metabolic Syndrome Type II Diabetes Hypertension Hypercholesterolaemia Ischaemic Heart Disease Obstructive Sleep Apnoea
Pre-assessment Clinic Rationale 1. Screening tool for Occult Disease 2. Optimisation of Preexisting Conditions 3. Assessment of Fitness for Surgery
Pre-assessment Clinics Surgical Clinic Pre-assessment Clinic Nurse STOP BANG Anaesthetist MDT Routine investigations 1. Unfit; risks>benefits 2. Unfit; benefits>risks 3. Fit Sleep Study Fit if optimised Specialist investigations CPX fitness/triage Endocrinology Cardiology Respiratory Psychology 2-6 weeks
Pre-assessment Clinic Rationale Screening tool for Occult Disease SLEEP APNOEA Optimisation of Preexisting Conditions Assessment of Fitness for Surgery CPEX
Obstructive Sleep Apnoea APNOEAS - Abnormal pauses in breathing HYPOAPNOEAS - Abnormal episodes of shallow breathing The Airway Bone Airway Soft tissue From Watanabe et al Copyright 2009, the American Society of Anesthesiologists, Inc. Lippincott Williams & Wilkins, Inc.
Obstructive Sleep Apnoea APNOEAS - Abnormal pauses in breathing HYPOAPNOEAS - Abnormal episodes of shallow breathing The Airway Bone Airway Soft tissue Reduced Luminal Diameter Negative Insp Pressure Further Airway Narrowing Inc Airway Resistance Greater Insp Effort Required Airway Occlusion
Obstructive Sleep Apnoea Incidence of OSA Mild 20% Moderate / Severe 7% Symptoms Daytime somnolence, fatigue Impaired Alertness, slower reactions, vision problems Leads to Behavioral changes moodiness, decreased attention and drive Morning Headache Often Symptoms Ignored by Patient Often Symptoms Misdiagnosed Recent Interest in Effect of Sleep Disturbance on Appetite Regulation and Glycaemic Control
STOP BANG Predictor for Sleep Apnoea STOP S (snore) Loud Snoring T (tired) Daytime Tiredness Sensitivity 65% O (observed) Cessation of Breathing During Sleep Specificity 60% P (blood Pressure) Have or being treated for High Blood STOP-BANG Pressure Combined BANG Sensitivity 91% B (body mass index) Specificity BMI >35kgs/m2 74% A (age) Age >50 years Sensitivity 84% N (neck) Neck Circumference Specificity >40cm 56% G (gender) Male Chung F, Yegneswaran B, Liao P, Chung SA, Vairavanathan S, Islam S, Khajehdehi A, Shapiro CM. Validation of the Berlin questionnaire and American Society of Anesthesiologists checklist as screening tools for obstructive sleep apnea in surgical patients. Anesthesiology 2008; 108: 822-30. [Conclusion; STOP Sens 65.6%, Spec 60% (PPV 78; NPV 44). BANG Sens 83.6%, Spec 56.4% (PPV 81; NPV61). Combined 91% and 74% respectivelly. Grade C recommendation]
Your typical patient with OSA! Snores at night! Has morning headache! Tires during the day Under diagnosed Validation of the American Society of Anesthesiologists checklist as screening tools for obstructive sleep apnea in surgical patients. Anesthesiology 2008; 108: 822-30
Your typical patient with OSA! Male! Past 40! Overweight
Your typical patient with OSA Nocturnal oximetry 1 2 3 1. 4% sats drop/ hr = 86/hr = AHI index 2. Average sats [=81%] 3. Lowest sats [=50%]
Your typical patient with OSA Nocturnal oximetry 1 2 3 1. Apnoea 4% sats Hypopnoea drop/ hr Index = 86/hr = AHI index (AHI) 2. Average sats [=81%] 3. Lowest 5-15 sats [=50%] mild 15-30 moderate >30 severe
Assessment of Fitness for Surgery After Optimisation of Pre existing Conditions Is Patient Fit to Withstand General Anaesthetic? Is Patient fit to Survive a Complication of Surgery? Quantify Risk of Surviving Surgery What is the Anaerobic Threshold?
Cardio pulmonary exercise test (CPX) Cycle ergometer On-mouth pneumotachograph to measure flow of gases Gas sampling to O2 and CO2 sensors to record O2 used and CO2 produced in ml/kg/ min Continuous 12 lead ECG and ST segment analysis Exercise increased till the rise in CO2 exceeds the slope of the O2 supply. This O2/CO2 crossover is referred to as the anaerobic threshold (AT)
Cardio pulmonary exercise test (CPX) Results Degree of exercise or tolerance ECG changes: heart rate, arrhythmias and their type, ST levels Pulmonary function test - dynamic Anaerobic Threshold (AT)
The Physiological Principle Anaerobic Threshold CO2 Production (ml/min) Aerobic Metabolism Anaerobic Contribution To Metabolism O2 Consumption (ml/min) VO2 (ml/min)
Level of care triage Normal Anaerobic Threshold (AT) - >16mls/kg/min AT >11 No recommendation of augmented level of care on the basis of CPEX results AT < 11 Consider Intensive recovery, PACU, HDU or ICU AT < 8, Consider/prepare for extended stay on ICU
Level of care triage Normal Anaerobic Threshold (AT) - >16mls/kg/min 75kg man AT = 10mls/kg/min = 750kg/min Breathing Takes 250 mls/min Sitting Takes 500 mls/min Getting Out of Bed Takes 750 mls/min If Hb drops 12g/dl to 8g/dl Or Atelaxesis and VQ mismatch Acidosis
Advice on risk of surgery AT >11 - periop mortality less than 1%; AT < 11- periop CVS mortality 18%; AT < 8 - periop CVS mortality 50%; in patients> 65yrs
One Stop Proforma
Diabetes Optimisation Poor preoperative glycaemic control is associated with increased postoperative morbidity and mortality Optimisation of DM control can reduce postoperative mortality by 50% Aim for HbA1C < 69 mmol/mol (8.5%) prior to surgery
Lifestyle Changes Stop Smoking Increase Activity Levels Preoperative Diet Psychological Counselling
Summary Pre-assessment Essential for All Surgical Patients Be Aware of Sleep Apnoea Use CPEX Assessment to Quantify Risk