The impact of heated humidified circuits on arterial oxygenation during one-lung ventilation in thoracic surgery: a randomized controlled trial.

PURPOSE

One-lung ventilation (OLV) during thoracic surgery often disturbs systemic oxygenation. Hypoxic pulmonary vasoconstriction is influenced by body temperature; however, the effect of heated humidified circuits on hypoxic pulmonary vasoconstriction and arterial oxygenation during OLV remains unclear. This study aimed to investigate the impact of heated humidified circuits on arterial oxygenation during OLV for thoracic surgery, compared with conventional non-heated circuits.

METHODS

Patients undergoing video-assisted thoracic surgery were randomly assigned to the heated humidified circuit or conventional breathing circuit group. During two-lung ventilation, tidal volume was set at 8 ml/kg with a fraction of inspired oxygen (FiO) of 0.5, and during OLV, it was adjusted to 6 ml/kg with a FiO of 1.0. Arterial blood gas measurements were obtained preoperatively, during two-lung ventilation, at 15, 30, 45, and 60 min after initiating OLV. The primary outcome was the partial pressure of oxygen in the arterial blood (PaO) at 30 min after initiating OLV.

RESULTS

Ninety-seven patients were included in the final analysis. The heated humidified circuit group had significantly higher PaO₂ at 30 min after initiating OLV than the control group (estimated mean [standard error], 211.3 [13.4] vs. 146.2 [13.2] mmHg; P = 0.004). The mean PaO at 15 and 45 min was significantly higher in the heated humidified circuit group.

CONCLUSION

Using heated humidified circuits significantly improves PaO during OLV in patients undergoing thoracic surgery compared to conventional circuits. These findings suggest that heated humidified circuits can be considered as an option when hypoxemia persists despite other interventions.