A 180cm, 200kg man presents to ICU following emergency cholecystectomy. How does his obesity affect his physiology and how may it influence his ICU management?
a) Obesity affects the physiology of several systems:
Cardiovascular- there is increased left and right ventricular stroke work with a tendency to left ventricular hypertrophy.
Hypertension is significantly correlated with obesity
Respiratory- total respiratory compliance is reduced by decreased chest wall compliance with fat accumulation subcutaneously and intraabdominally. There is a reduction in FRC caused by
reduced ERC. If FRC is less than closing capacity, hypoxia may ensue.
b) Obesity influences his ICU management via:
1) interference with normal physiology (as above)
2) coexisting medical problems (hypertension, ischaemic heart disease, diabetes, sleep apnoea, pulmonary hypertension)
3) technical difficulties with
- monitoring devices (eg NIBP cuffs)
- bed size (nerve compression)
4) difficulty mobilising
- Pressure areas
Paul Marik has published an excellent review of this in 1998.
Since the late 1990s, obesity has remained obesity, and so I think this article is still very relevant.
Akinnusi, Morohunfolu E., Lilibeth A. Pineda, and Ali A. El Solh. "Effect of obesity on intensive care morbidity and mortality: A meta-analysis*." Critical care medicine 36.1 (2008): 151-158.
Marik, Paul, and Joseph Varon. "The obese patient in the ICU." CHEST Journal113.2 (1998): 492-498.
Ling, Pei-Ra. "Obesity Paradoxes—Further Research Is Needed!*." Critical care medicine 41.1 (2013): 368-369.