27: Anaesthesia and obesity

27

Anaesthesia and obesity

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Obesity (obesus (Latin) = fattened by eating) is a major health problem. Virtually unheard of at the end of the Second World War, it is now a national epidemic. Although multifactorial, a diet high in fat and refined sugars, combined with low levels of activity, have contributed to its increase. Less common causes include endocrine disorders (e.g. Cushing disease and hypothyroidism). There is also a genetic component; adoption studies have shown a 70% chance of obesity if both parents are obese compared to 20% in those of normal weight.

In 2010, 26% of adults (>16 years old) in the UK were classified as obese and 30% of children (2–15 years) were overweight or obese.


Assessing weight and obesity
Body mass index (BMI) is calculated as: weight in kg/height in m2
BMI <20: underweight
BMI 20–25: normal
BMI 25–30: overweight
BMI 30–35: obese
BMI >35: morbidly obese
BMI >45: super morbidly obese
Ideal body weight in kg (IBW) is calculated as: height in cm −100 for men; height in cm −105 for women.
Although useful as a guide, neither takes account of age, muscle mass or fat distribution. Body fat content for men is 18–25% and for women is 20–30%. A professional footballer would have 12% body fat and a marathon runner 7%.

Fat distribution

Centripetal (android) obesity (Figure 27.1) confers added risk of developing ischaemic heart disease, glucose intolerance, Type 2 diabetes, dyslipidaemias, CVS disease, LV dysfunction and CVA. This is possibly due to products of visceral fat delivered directly to the portal circulation.

In peripheral (gynaecoid) obesity (Figure 27.1) fat accumulates on hips, buttocks and thighs. This is more common in women and confers some protection from conditions such as diabetes and ischaemic heart disease.

The complications of obesity affect all physiological systems (Figure 27.2). Obese patients have increased morbidity and mortality from anaesthesia and surgery.

Respiratory system

Obstructive sleep apnoea (OSA)

Patients with OSA experie/>

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Jan 12, 2015 | Posted by in Oral and Maxillofacial Surgery | Comments Off on 27: Anaesthesia and obesity
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