Early pulmonary compliance increase during cardiac surgery predicted post-operative lung dysfunction

Area of Science:

• Cardiology
• Pulmonology
• Anesthesiology

Background:

• Lung dysfunction post-cardiac surgery is attributed to atelectasis and lung injury.
• The exact pathogenesis of lung injury following cardiopulmonary bypass remains unclear.
• This study investigates a potential mechanical etiology for lung injury.

Purpose of the Study:

• To examine the relationship between changes in pulmonary compliance and lung dysfunction after cardiac surgery.
• To determine if mechanical factors during surgery contribute to post-operative hypoxemia.

Main Methods:

• Pulmonary compliance (static and dynamic) was measured at six critical points during cardiac surgery in 62 patients.
• Changes in compliance due to thorax opening (ΔCstat1, ΔCdyn1) and cardiopulmonary bypass (ΔCstat2, ΔCdyn2) were calculated.
• Lung dysfunction was assessed using the PaO2/FiO2 ratio, and correlations between compliance changes and lung dysfunction were analyzed.

Main Results:

• Pulmonary compliance increased upon thorax opening and decreased with cardiopulmonary bypass initiation.
• The PaO2/FiO2 ratio decreased post-surgery, indicating lung dysfunction.
• Increased compliance from thorax opening was negatively correlated with worsened intrapulmonary shunt (∆PaO2/FiO2) and changes in compliance during cardiopulmonary bypass.

Conclusions:

• Elevated pulmonary compliance during thoracic opening correlates with increased intrapulmonary shunt post-cardiopulmonary bypass.
• Mechanical phenomena during cardiac surgery may play a role in causing post-operative hypoxemia.