Arterial oxygen desaturation during apnea in humans

Area of Science:

• Physiology
• Human Diving Response

Background:

• The human diving response is characterized by bradycardia and reduced peripheral blood flow.
• Understanding its effect on arterial hemoglobin oxygen saturation is crucial for physiological studies.

Purpose of the Study:

• To investigate how the human diving response, induced by apnea in air and face immersion, affects arterial hemoglobin desaturation.
• To determine if face immersion potentiates the diving response and influences oxygen saturation changes.

Main Methods:

• 21 subjects performed apneas in air and with face immersion in 10°C water.
• Non-invasive methods recorded heart rate, skin capillary blood flow, blood pressure, and arterial oxygen saturation.
• Apnea duration was consistent for each subject across conditions.

Main Results:

• Face immersion significantly potentiated bradycardia (13.6%) and reduced capillary blood flow (55.9%) compared to apnea in air (7.8% and 37.7%).
• Arterial hemoglobin desaturation was less pronounced during apnea with face immersion (1.4%) than during apnea in air (2.7%).

Conclusions:

• Potentiation of the human diving response by face immersion in cold water results in a smaller decrease in arterial hemoglobin saturation.
• This suggests a potential oxygen-conserving effect of the diving response when face immersion is involved.