Effect of low calorie intake on abnormal pulmonary physiology in patients with chronic hypercapneic respiratory failure.

To explore the effects of low calorie, low carbohydrate intake on abnormal pulmonary physiology in chronic hypercapneic respiratory failure, spirometric, arterial blood gas tension, oximetric, and electrocardiographic studies were carried out before and after weight reduction in eight patients. During a single night of monitoring, the mean basal oxygen saturation was 68.4 +/- 20.7 percent with 38 hypoxemic "dips" (a fall in oxygen saturation of more than 10 percent for one minute or longer); six patients had resting tachycardia, four had a prolonged QTc interval, three showed multiple episodes of ST-T depression, and six patients had multiple atrial and ventricular premature contractions. After a low calorie (600 kcal per day) intake for 4.4 +/- 2.3 weeks, there was a mean weight loss of 8.5 +/- 3.6 kg, the mean arterial oxygen tension increased significantly (p less than 0.005) from 55.6 +/- 9.2 to 69.1 +/- 7.9 torr, the mean arterial carbon dioxide tension fell from 59.9 +/- 9.6 to 52.4 +/- 5.4 torr (p less than 0.01), the mean oxygen saturation increased significantly (p less than 0.05) to 85.0 +/- 9.0 percent with only two hypoxemic "dips," the resting heart rate decreased from a mean of 100 +/- 19 to 90 +/- 18 beats/per minute (p less than 0.05), there was a marked reduction in ectopic activity, the ST-T depression disappeared, and the QTc interval fell in two subjects. Follow-up data in four patients suggest that the improvements achieved in arterial blood gas values can be maintained with a low calorie intake. These studies show that a low calorie, low carbohydrate intake improves all the unfavorable physiologic abnormalities in chronic hypercapneic respiratory failure.