Transcript Obesity- Challenge in Everyday Practice

Dr.N.Balasubramaniyam
Consultant Anaesthetist
S.K.S Hospital
Salem
OBESITY,CHALLENGES IN
DAILY LIFE
Discussion….
 "Overweight"
is a sensitive topic.
 Body
mass index (BMI) levels that
categorize fatness.
 BMI
can potentially misclassify
people as fat

‘Trust your own judgement about your body !
because
BMI-based body descriptions can be wrong’.
_ by Steven B. HallMD
For Adults
“Overweight“
BMI of 25 & above
“OBESE”
BMI of 30 & more
- CDC & WHO
CHILDREN
overweight
BMI >85th percentile
Obese
BMI>95th percentile
BMI





Classification
<25 Normal
25-30 Overweight
>30 Obese
>35 Morbidly obese
>55 Super-morbidly obese
Body Weight Calculations
Types of Fat distirbution

Gynaecoid Typefat distributed in peripheral sites
(arms, legs, and buttocks)

Android Typecentral fat distribution
(intraperitoneal fat)
Waist-to-hip ratio
>0.8 in women
or
1.0 in men is typical of the android
distribution
Android distribution
“Risk of metabolic and cardiovascular complications”
- intra abdominal surgery more difficult and
is associated with increased fat deposition
around the neck and airway
Waist or collar circumference
More predictive of cardiorespiratory comorbidity
than BMI !!!
Effects of Fat distribution
Comorbidity








Hypertension
Dyslipidaemia
Ischaemic heart disease
Diabetes mellitus
Osteoarthritis
Liver disease
Asthma
Obstructive sleep apnoea (OSA)
Respiratory System

OSA

Episodes of apnoea or hypopnoea during sleep secondary to
pharyngeal collapse
Five or more per hour or >30 per night
snoring; day-time somnolence, associated with impaired
concentration and morning headaches

OSA…

Pathophysiological changes:
Hypoxaemia
(leading to secondary polycythaemia)
Hypercapnia
Systemic vasoconstriction, &
Pulmonary vasoconstriction
(right ventricular failure)
OSA
&
Airway

Adipose tissue in the pharyngeal wall increased

pharyngeal wall compliance increased
(airway collapse during negative pressure)
Airway geometry

(Antero-posterior axis is more than lateral)

Genioglossus tone increased
(less effective in maintaining airway patency)

Increased reliance on hypoxic drive
-type 2 respiratory failure
Obesity Hypoventilation syndrome
Relative leptin insensitivity in obesity decreases
ventilatory response to Co2
Depressant drugs, including many anaesthetic agents
and analgesics, accentuate this
Cardiovascular System





Blood volume, cardiac output, ventricular workload, oxygen
consumption, and CO2 production are all increased
Absolute blood volume is increased-45 ml kg-1
'Obesity cardiomyopathy‘
arrhythmias because of: myocardial hypertrophy and
hypoxaemia; hypokalaemia from diuretic therapy; coronary artery
disease; increased circulating catecholamines; OSA (sinus
tachycardia and bradycardia); and fatty infiltration of the
conducting and pacing systems.
Ischaemic heart disease is more prevalent
Pharmacokinetics


Calculation of appropriate dosages may be
difficult
Most of the general anaesthetic drugs are
affected by the mass of Adipose tissue
Pharmacokinetics of obesity

The main factors that affect tissue drug
distribution in any patient are
plasma protein binding
body composition and
regional blood flow.

Highly fat-soluble drugs - increased volume
distribution
e.g. benzodiazepines and barbiturates – have prolonged
effect

Less fat-soluble drugs-No change in volume
distribution
e.g. neuromuscular blocking agents
Exception is succinylcholine & PropofolShould be dosed toTotal body weight
Reduce 25% of spinal & epidural dose
Preoperative Assessment

Many morbidly obese patients have limited
mobility and may therefore appear relatively
asymptomatic!!!
despite having
significant cardio-respiratory dysfunction




Drug history,
Look for Symptoms and signs of cardiac failure
OSA
Unable to lie flat for Several years So an
assessment of the ability to tolerate the supine
position may reveal unexpected profound
oxygen desaturation, airway obstruction, or
respiratory embarrassment
IV access by central venous cannulation
Ottestad E et al. Anesth Analg 2006;102:1293-1294
©2006 by Lippincott Williams & Wilkins
A chest radiograph obtained after placement of the 20-cm
double-lumen subclavian catheter.
Ottestad E et al. Anesth Analg 2006;102:1293-1294
©2006 by Lippincott Williams & Wilkins
Preoperative Airway Assesment
Predictors of difficult airway







BMI
Mallampati classification
Neck circumference
Thyromental distance
Obstructive sleep apnoea symptoms
Gastro-oesophageal reflux disease
Cervical fat pad or hump
Positioning


Ramped or semi sitting position
Head-Elevated Laryngoscopy Position (HELP)
Positioning….
Proper head-elevated
laryngoscopy position (HELP
Positioning…..
Intra-Operative






Pulmonary atelectasis occurs in 85%- 90% of
healthy adults within minutes after the induction
of general anesthesia
Atelectasis is larger in obese patients or when a
high fraction of inspired oxygen (FiO2) is used
Degree of head-up tilt may slow the rapid
desaturation
Awake fibreoptic intubation
PEEP
short-acting anaesthetic agents
Post-Operative






Extubated wide-awake in the sitting position
CPAP
Post-operative ventilation-Awake& Less
sedation with PS mode
NSAIDs- best omitted
Acetaminophen, Patient-controlled opioid
analgesia, or regional anaesthesia
Early mobilization -reduces postoperative atelectasis
& venous thromboembolism
Catabolic response to surgery use Insulin to maintain
normoglycemia
.

Keypoints..






Obesity-independent risk factor
Plasminogen activator inhibitor-1
Gastric emptying is delayed
Rhabdomyolysis
Difficulty of laryngoscopy
The 400 J of energy on regular defibrillators
Take Home…

Proper Positioning
Early Extubation
DVT prophylaxis – during peri operative period

Effective postoprative analgesia

