BMI Calculator
Calculate Body Mass Index for preoperative assessment and risk stratification.
Clinical Context
Body Mass Index (BMI) is a heuristic proxy for human body fat based on an individual's weight and height. In surgical practice, extremes of BMI (both underweight and severe obesity) are independent predictors of perioperative morbidity and mortality.
Surgical Implications of High BMI
- Airway management: Increased risk of difficult intubation and rapid desaturation.
- Respiratory: Reduced functional residual capacity (FRC), increased risk of atelectasis and post-op pneumonia.
- Cardiovascular: Higher prevalence of undiagnosed ischemic heart disease, hypertension, and arrhythmias.
- Thrombosis: Significantly increased risk of DVT/PE; requires aggressive prophylaxis.
- Wound complications: Increased rates of surgical site infection (SSI), seroma, and dehiscence.
WHO Classification
- Underweight < 18.5
- Normal range 18.5 - 24.9
- Overweight 25.0 - 29.9
- Obese Class I 30.0 - 34.9
- Obese Class II 35.0 - 39.9
- Obese Class III ≥ 40.0