Clinical semi-starvation: depression of hypoxic ventilatory response

Area of Science:

• Physiology
• Nutritional Science

Background:

• Decreased metabolic rate is linked to impaired ventilatory control during starvation.
• Understanding the impact of caloric restriction on respiratory function is crucial.

Purpose of the Study:

• To investigate the effects of semi-starvation on metabolic rate and ventilatory responses in humans.
• To determine the relationship between metabolic rate and hypoxic/hypercapnic ventilatory responses during caloric restriction.

Main Methods:

• Seven healthy subjects underwent a 10-day, 500-calorie carbohydrate diet with electrolyte supplementation.
• Metabolic rate and ventilatory responses to hypoxia and hypercapnia were measured.
• Changes were assessed before, during, and after refeeding.

Main Results:

• By day 10, metabolic rate significantly decreased.
• Hypoxic ventilatory response was reduced by 42% (P < 0.05), with near abolition in two subjects.
• Hypercapnic ventilatory response showed a non-significant decrease.
• Reductions in hypoxic ventilatory response correlated significantly with decreased metabolic rate (P < 0.01).

Conclusions:

• Semi-starvation markedly impairs hypoxic ventilatory response, linked to reduced metabolic rate.
• This impairment may contribute to hypoxemia and respiratory failure in caloric restriction.
• Ventilatory responses normalized upon refeeding.