BMI ≥35 (Obese Class II) significantly increases surgical risk — longer anaesthesia, wound complications, DVT, respiratory issues. BMI ≥40 may warrant specialist input before elective procedures.
IBW is the weight considered normal for a given height. Drug dosing (especially for anaesthetic agents) is often calculated on IBW rather than actual weight in obese patients.
For most anaesthetic drugs, use lean body weight or IBW in obese patients. For specific drugs consult pharmacy. This calculator shows IBW as a reference.
BMI ≥40, or BMI ≥35 with obesity-related comorbidities (diabetes, hypertension, sleep apnoea), is the standard threshold for bariatric surgery referral.