Functional Evaluation in Obese Patients Before and After Sleeve Gastrectomy

Although sleeve gastrectomy (SG) has become an important treatment option in severe obesity, cardiorespiratory and muscle function after SG has not adequately been investigated.

This is an observational study in 26 obese patients (BMI 45.2 ± 5.8 kg/m²), comparing physical function before and after 6 months from SG. All available patients listed for SG were here included. Incremental cardiopulmonary exercise tests, standardized strength tests, and balance analysis were performed.

The substantial weight loss (-33.4 ± 11.0 kg) after SG led to increased peak work capacity (metabolic equivalents, METs) and relative peak oxygen uptake (VO₂peak/kg) (both p < 0.001). However, the absolute VO₂peak, oxygen pulse (VO₂/heart rate (HR)), and the oxygen uptake efficiency slope (OUES) significantly declined after SG (all p < 0.001). Furthermore, HR/VO₂-slope significantly worsened after SG (p < 0.001), whereas the HR reserve and HR recovery improved (all p ≤ 0.01). Parameters of ventilatory efficiency were not affected by SG. The time-constant (Tau τ) of the fundamental component of VO₂-kinetics, reflecting oxygen metabolism in skeletal muscles, was found to be significantly worsened after SG (p < 0.05). Finally, muscle strength and balance parameters were not much affected by SG.

The ventilatory and cardiac function do not appear negatively affected by SG; thus, we hypothesize that the decrease in aerobic capacity could be due to alterations in peripheral muscles. This might in part be due to a loss of muscle mass, although our patients' muscle strength did not decrease. Pilot results from VO₂-kinetics analysis seem to support the hypothesis of a deterioration of oxidative muscle metabolism after SG.