Severe Obesity and Prolonged Postoperative Mechanical Ventilation in Elderly Vascular Surgery Patients

BACKGROUND: Severe obesity, defined as body mass index (BMI) ≥ 40 kg/m(2) is increasingly prevalent in elderly surgical patients. Although older age is associated with prolonged postoperative mechanical ventilation (PPMV), the contribution of obesity to this complication in the elderly has not been explored. We investigated the association of severe obesity with the PPMV and the role of severe obesity on mortality risk in patients requiring PPMV. METHODS: We assembled a retrospective cohort of patients ≥ 65 years who underwent inpatient surgical procedures and were either severely obese or normal weight (BMI 18.6 - 24.9 kg/m(2) (National Surgical Quality Improvement Program (NSQIP) 2015 - 2018). PPMV was defined as requirement of postoperative mechanical ventilation for longer than 48 h following surgery. We examined the association between severe obesity and PPMV, using univariable and multivariable logistic regression. RESULTS: We studied 34,936 patients who were ≥ 65 years of age. The incidence of PPMV was 2.0% (624/31,700) in normal weight patients and 2.8% (92/3,236) in severely obese patients (odds ratio (OR): 1.46; 95% confidence interval (CI): 1.17 - 1.82, P = 0.001). Multivariable analysis, controlling for confounders, estimated a 56% relative increase in the risk of PPMV in severely obese patients, relative to their normal weight peers (OR: 1.56; 95% CI: 1.22 - 1.99, P = 0.001). In normal weight patients, the risk of mortality was multiplied by 23 times in patients who required PPMV (39.6% vs. 2.64%; OR: 23.10; 95% CI: 18.96 - 28.16; P < 0.001). In severely obese patients, PPMV multiplied the risk of mortality by 25 times (30.4% vs. 1.6%; OR: 25.26, 95% CI: 13.44 - 47.50; P < 0.001). CONCLUSIONS: Severe obesity increased the odds of PPMV. Although the incidence of PPMV was low, its requirement conferred up to 25 times greater risk of postoperative mortality, underscoring the need for perioperative mitigation strategies to minimize PPMV risk in elderly patients undergoing vascular surgery.