Weight loss and metabolic changes of morbidly obese patients after gastric partitioning operation.

UNLABELLED: Weight loss, alterations in basal metabolic rate, and utilization of body fat, carbohydrate, and protein substrates were studied in nine patients before operation and 3 and 12 months after gastric partitioning operation for morbid obesity. Respiratory oxygen consumption and carbon dioxide excretion measurements were taken three consecutive mornings by the open circuit-Scholander technique. Measurements of urine urea nitrogen were made from 24-hour urine collections. Basal metabolic rate and utilization of fat, carbohydrate, and protein were calculated in kilocalories per minute by indirect calorimetry. Initial body weight was 124.5 +/- 19.0 kg (mean +/- SD). The weight losses between measurements at months 0 and 3 and at months 3 and 12 were 20.8 +/- 4.6 kg and 2.7 +/- 8.4 kg, respectively. Total weight loss between months 0 and 12 was 23.5 +/- 8.3 kg (19.3% +/- 7.4%). At 3 months the fraction of basal metabolic rate contributed by carbohydrate (p less than 0.05) and protein (p less than 0.01) utilization decreased significantly, while that contributed by fat increased (p less than 0.05). Between months 0 and 12 there was no significant difference in protein or carbohydrate utilization, but fat utilization increased (p less than 0.10). CONCLUSIONS: Gastric partitioning operation resulted in an initial rapid body weight loss over 3 months with a sustained reduction over 1 year; there was a metabolic utilization shift to fat with carbohydrate and protein sparing; no metabolic parameter was predictive of weight loss; and temporally, the rapid weight loss was paralleled by a significant metabolic utilization shift, and the sustained loss was paralleled by a stabilization of this shift.

Instrumentation simultaneously measuring VCO2 and VO2 in humans using titration methods.

An instrument has been developed for the simultaneous measurement of carbon dioxide excretion (VCO2) and oxygen uptake (VO2). This instrument, the Nutrimeter, gives these breath-averaged measurements continuously without having to determine respiratory flow rate, perform timed spirometric gas collections, or determine absolute CO2 or O2 concentrations. It can be used on ventilated or nonventilated patients in long- and short-term studies. VO2 is determined via the replenishment technique. VCO2 is determined via a new technique, absorption-titration, described here. Bench test results of VCO2 measurements show a standard error of the estimate (SEE) +/- 0.591% of full scale (500 ml/min) and maximum single point error (MSPE) of +/- 3.54% over a 100--350 ml/min range. VO2 measurements show SEE +/- 0.518% of full scale (1,000 ml/min) and MSPE +/- 2.42% over a 100--450 ml/min range. In 31 human clinical trials the Nutrimeter was compared with the open-circuit spirometric collection and micro-Scholander analysis technique. VCO2 measurements show SEE +/- 2.208% and MSPE +/- 10.57% over 135--315 ml/min. VO2 measurements show SEE +/- 1.134% of full scale and MSPE +/- 9.54% over 170--360 ml/min. Response time is 60 s optimally for step changes in VO2 (0--90% of steady-state value), 90 s for VCO2.