Excessive body weight in relation to height, usually quoted as Body Mass Index, BMI (weight in kg/height in m²). According to the WHO, a person with a BMI which is greater or equal to 25 is overweightand one which is greater or equal to 30 is obese.

Condition specific perioperative analgesic issues

Morbid obesity is strongly associated with Obstructive Sleep Apnoea (OSA). OSA is exacerbated by centrally-acting respiratory depressant drugs eg opioids, which may precipitate hypoventilation, hypoxemia, hypercapnia, acidosis, loss of consciousness, cardio-respiratory arrest, pulmonary hypertension and right ventricular heart failure. ANZCA chapter 11.5, p 411

Evidence based recommendations specific to the condition

The evidence for the management of pain in obese patients is limited and, therefore, recommendations are mainly derived from commonality in treating patients with OSA.

Recommended treatment options

The use of PCA with appropriate bolus doses and monitoring has been reported as no less safe than regional or other systemic opioid analgesic technique. Note the studies lacked sufficient power. ANZCA chapter 11.5, page 413.

Condition specific issues related to nursing\monitoring patients

Morbidly obese patients undergoing bariatric surgery may be at increased risk of postoperative hypoxemia independent of OSA. ANZCA chapter 11.5, ‘Key messages’, page 413

Summary

Due to the limited evidence about management strategies of obese patients, recommendations about postoperative pain treatments are based on those for OSA patients and include, multimodal, opioid sparing analgesia and local, regional and neuroaxial analgesia-based techniques.

Supplementary reading

1. Al-Nasser B. Review of interscalene block for postoperative analgesia after shoulder surgery in obese patients. Acta Anaesthesiol Taiwan. 2012 Mar;50(1):29-34.
2. Barg A, Knupp M, Anderson AE, Hintermann B. Total ankle replacement in obese patients: component stability, weight change, and functional outcome in 118 consecutive patients. Foot Ankle Int. 2011 Oct;32(10):925-32.
3. Gross JB, Bachenberg KL, Benumof JL, et al; American Society of Anesthesiologists Task Force on Perioperative Management.Practice guidelines for the perioperative management of patients with obstructive sleep apnea: a report by the American Society of Anesthesiologists Task Force on Perioperative Management of patients with obstructive sleep apnea. Anesthesiology. 2006 May;104(5):1081-93.
4. Subhani M, Rizvon K, Mustacchia P. Endoscopic Evaluation of Symptomatic Patients following Bariatric Surgery: A Literature Review Diagn Ther Endosc. 2012;2012:753472.