Effect of liver failure on the ventilatory response to hypoxia in man and the goat

Area of Science:

• Cardiovascular Physiology
• Respiratory Physiology
• Hepatic Physiology

Background:

• Hepatic cirrhosis can lead to complex physiological changes affecting respiratory control.
• The impact of liver failure on ventilatory responses to hypoxia requires further elucidation.

Purpose of the Study:

• To investigate ventilatory responses to transient and steady-state hypoxia in patients with hepatic cirrhosis.
• To assess the effects of experimentally induced liver failure on respiratory control in goats.

Main Methods:

• Measured ventilatory responses to transient and steady-state hypoxia in cirrhotic patients and healthy controls.
• Induced liver failure in goats to study changes in hypoxic ventilatory response and hypercapnia response.
• Evaluated the effect of hypoxia on hypercapnia response before and after liver failure.

Main Results:

• Patients with hepatic cirrhosis showed a greater response to transient hypoxia compared to controls, despite respiratory alkalosis.
• In goats, liver failure increased the response to transient hypoxia but created a disparity with unchanged steady-state hypoxic response.
• Steady-state hypoxia enhanced hypercapnia response in healthy goats but depressed it in goats with liver failure.

Conclusions:

• Liver failure appears to increase peripheral chemoreceptor sensitivity to hypoxia.
• Central respiratory centers may become more susceptible to hypoxic depression during liver failure.
• A dissociation between transient and steady-state hypoxic ventilatory responses emerges during liver failure.