Effect of low tidal volume with PEEP on respiratory function in infants undergoing one-lung ventilation.

BACKGROUND: An increasing number of studies have shown that low tidal volume (TV) with positive end-expiratory pressure (PEEP) offers lung protection during one-lung ventilation (OLV). Considering the unique physiological characteristics of infants, we aimed to determine the feasibility and effect of low TV with PEEP in infants undergoing OLV during thoracoscopy.

PATIENTS AND METHODS: We randomized 60 infants to a conventional group (group I: TV, 8-10 ml/kg; RR, 23-45 bpm; PEEP, 0 cmH2 O) or a low TV with PEEP group (group II: TV, 5-7 ml/kg; RR, 23-45 bpm; PEEP, 4-6 cmH2 O). Arterial blood gas analyses were performed at four time points: 5 min of two-lung ventilation (TLV, T0 ), and 20 min, 40 min, and 60 min of OLV (T1 , T2 , T3 ); hemodynamic parameters (heart rate, mean blood pressure), temperature, as well as gas exchange (SpO2 and PET CO2 ) and ventilation parameters (FiO2 , PEEP, Pmax ) were recorded simultaneously. Lung compliance and shunt were also calculated.

RESULT: No significant difference was found between both groups at T0 . Compared with T0 , PET CO2 , Pmax , PaCO2 , lactic acid, and intrapulmonary shunt volume (Qs/Qt) were increased while PaO2 and respiratory system compliance (Cdyx) were decreased noticeably in both groups at T1 , T2 , and T3 . At T1 , T2 , and T3 , Pmax and Qs/Qt were much lower while PET CO2 , PaCO2 , and Cdyx were higher in group II than in group I. There was no significant difference in lactic acid and PaO2 measurements between the two groups at T1 , T2 , and T3 .

CONCLUSION: Low TV with PEEP could be an effective intraoperative ventilation strategy for infants undergoing OLV during video-assisted thoracoscopic surgery and may reduce the risk of lung injury. However, this strategy, as well as the influence of intraoperative hypercapnia on infants, needs further investigation.