Lung separation in children: Options and impact on gas exchange and lung compliance

One-lung ventilation is a challenging airway technique in the pediatric population. Multiple airway devices can be employed, but there is no consensus as to the most reliable and physiologically advantageous method. This report is a review of the methods of one-lung ventilation in children in our practice, as well as an analysis of the impact of airway device type, patient age, and duration of lung separation on respiratory mechanics and gas exchange.

The records of all pediatric patients undergoing procedures requiring one-lung ventilation in a single center over an 18-month period were reviewed. Demographics, time required to achieve lung separation (anesthesia ready-time), and duration of one-lung ventilation were collected. Data from arterial blood gas analysis and ventilator parameters were collected at three time points: 15 minutes prior to one-lung ventilation (pre-OLV), 15 minutes after initiation of one-lung ventilation (during OLV), and 15 minutes after one-lung ventilation was ended (post-OLV). Standard equations for calculating compliance, the ratio of arterial partial pressure of oxygen to the fraction of inspired oxygen, and the alveolar-arterial oxygen gradient were used.

Forty-six patients were identified with a mean age of 9.3 (inner quartile range 3-15) years. All patients had significant changes in pulmonary function when comparing pre-OLV with during OLV and when comparing during OLV with post-OLV. There were no significant changes from pre- to post-OLV. On further analysis, there were more pronounced changes in compliance and gas exchange in older patients (P = 0.003; 95% CI: -0.62 to -0.14). There was also a significant decrease in post-OLV compliance with a longer duration of OLV (P = 0.018; 95% CI: -0.02 to <-0.01). Airway device type did not have significant impact on the parameters examined.

Our report demonstrates significant changes in lung function during one-lung ventilation. One particular device does not seem to be superior. Though pre-OLV measures of pulmonary function correlate closely with post-OLV, older age and a prolonged duration of one-lung ventilation did impact compliance.