Intermittent Hypoxia Associated with Sleep Apnea Disrupts Microvascular Hemodynamics and Oxygen Delivery

Area of Science:

• Physiology
• Cardiovascular Research
• Sleep Medicine

Background:

• Obstructive sleep apnea (OSA) is linked to recurrent intermittent hypoxia (IH).
• The acute effects of IH on systemic and microvascular hemodynamics and oxygen transport require further elucidation.
• Understanding these effects is crucial for managing OSA-related complications.

Purpose of the Study:

• To investigate the acute alterations in systemic hemodynamics, microvascular tone, and oxygen transport induced by cyclic intermittent hypoxia (IH).
• To compare these changes against a normoxic control condition using a relevant animal model.

Main Methods:

• Utilized a dorsal window chamber model in unanesthetized Golden Syrian hamsters.
• Applied cyclic oxygen (21%/10% O₂) for 60 minutes, with 30-second cycles.
• Employed hyperspectral imaging (HSI) for microvascular oxygen saturation (SO₂) and intravital microscopy for hemodynamic parameters and functional capillary density (FCD).

Main Results:

• IH exposure led to reduced mean arterial pressure, decreased arterial oxygen saturation, elevated heart rate, and increased blood lactate.
• Microvascular SO₂ declined rapidly, and arteriolar blood flow and FCD were significantly reduced.
• Despite decreased vascular resistance, oxygen delivery (DO₂) and oxygen extraction (VO₂) were insufficient, with an increased oxygen extraction ratio.

Conclusions:

• Cyclic intermittent hypoxia acutely disrupts peripheral microcirculatory function and oxygenation.
• The observed microcirculatory dysregulation highlights the challenges in maintaining adequate tissue oxygen supply during OSA.
• This study underscores the utility of IH models in evaluating oxygen transport dynamics relevant to obstructive sleep apnea.