Ventilatory Efficiency Identifies Patients Prone to Hypoxemia During One-Lung Ventilation

Area of Science:

• Anesthesiology and Critical Care Medicine
• Respiratory Physiology

Background:

• One-lung ventilation (OLV) is a critical procedure in thoracic surgery but can lead to hypoxemia.
• Ventilatory efficiency, measured as the ratio of minute ventilation to carbon dioxide output (VE/VCO2), is influenced by ventilation/perfusion mismatch and pulmonary artery hypertension, factors associated with hypoxemia.

Purpose of the Study:

• To investigate whether an increased VE/VCO2 slope can predict the development of hypoxemia in patients undergoing OLV.
• To identify physiological parameters associated with hypoxemia during OLV.

Main Methods:

• Prospective observational study involving 50 lung resection candidates at a tertiary care hospital.
• Cardiopulmonary exercise testing was performed pre-surgery.
• Hypoxemia during OLV was defined as requiring an inspired oxygen fraction (FiO2) ≥0.7 to maintain oxygen saturation >90% after 30 minutes.

Main Results:

• 48% of patients developed hypoxemia during OLV.
• Hypoxemic patients exhibited a significantly higher VE/VCO2 slope (30 ± 5 vs. 27 ± 4; p=0.04) compared to non-hypoxemic patients.
• Multiple regression analysis revealed that the VE/VCO2 slope was independently associated with oxygen saturation/FiO2 index during OLV (b=-0.28; p=0.05).

Conclusions:

• An elevated VE/VCO2 slope is a potential predictor of hypoxemia in patients undergoing OLV.
• This finding can assist in risk stratification and management strategies for patients during thoracic surgery requiring OLV.