Perioperative Changes in Functional Residual Capacity in Morbidly Obese Patients

Abstract

Functional residual capacity (FRC) was measured before and after induction of anaesthesia for jejunoileal bypass surgery in 30 morbidly obese patients. The onset of anaesthesia was associated with a 51% reduction in FRC from 2.2 litre to 1.0 litre. Eighteen of the patients were investigated more extensively; in these subjects FRC was reduced below the control values of residual volume (RV) with the onset of anaesthesia, but recovered towards baseline after laparotomy incision. Reduction in FRC is related to baseline vital capacity (VC) and FRC and is much greater than that reported for patients of normal weight.

Lung Stress and Strain during Mechanical Ventilation for Acute Respiratory Distress Syndrome

“…From the tracings, by resampling and an interpolation process (17), we obtained a single ''average'' breath for each patient and each ventilatory setting (Figure 2). Lung volumes were measured by helium dilution technique (18).…”

Perioperative functional residual capacity

“…27 The magnitude of reduction varies considerably and is primarily determined by body build, t J-~,~ In the morbidly obese, FRC can be as low as 50% of awake values. 26 Another major predictor of the magnitude of change is the severity of chronic airways disease expressed as FEVt/ FVC. 13 Such patients have a lower FRC than predicted on the basis of body build ( Figure 3b).…”

Reduced use of intensive care after liver transplantation: Patient attributes that determine early transfer to surgical wards

“…21,22 Respiratory impairment in obese patients caused by mass loading and splinting of the diaphragm is exacerbated by general anesthesia. 23 Increased minute ventilation to maintain normocapnea, augmented by an increased respiratory drive associated with liver disease, 24 helps explain the occurrence of respiratory insufficiency in 56% of our obese patients who were not extubated.…”