Effects of phenylephrine and norepinephrine with restrictive infusion on oxygenation during one-lung ventilation for lung surgery: a randomized controlled trial.

OBJECTIVE: This study compared the effects of norepinephrine or phenylephrine combined with restrictive infusion on the oxygenation during thoracoscopic one-lung ventilation (OLV). METHODS: Ninety patients were randomly divided into three groups: the norepinephrine group (Group N), the phenylephrine group (Group P), and the control group (Group C). Arterial partial pressure of oxygen (PaO2) and intrapulmonary shunt fraction (Qs/Qt) were measured with patients in lateral positions during two-lung ventilation (TLV) at 10 min (T1), and during OLV at 15 min (T2) and 45 min (T3). Lung tissue samples were analyzed for endothelin and COX-2 levels after surgery. RESULTS: At T3, Group P had significantly higher PaO2 and lower Qs/Qt than Groups N and C (all p < 0.05), with no significant differences between Groups N and C (all p > 0.05). Compared to T1, Groups N and C showed significantly lower PaO2 and higher Qs/Qt at T2 and T3 (all p < 0.05), with no significant differences in PaO2 and Qs/Qt at T3 compared with T2 (all p > 0.05). Group P patients had lower PaO2 and higher Qs/Qt at T2 and T3 compared to T1 (all p < 0.05), but at T3, PaO2 increased and Qs/Qt decreased compared to T2 (all p < 0.05). Lung tissue levels of endothelin and COX-2 were significantly elevated in group P compared to groups N and C (all p < 0.05). CONCLUSION: Combining phenylephrine with restrictive infusion during OLV improved oxygenation by increasing PaO2, decreasing Qs/Qt, and raising endothelin and COX-2 levels in lung tissue, thereby enhancing the HPV effect.