Especially in young patients, CO2 absorption with subsequent hypercapnia and acidosis is a major concern associated with thoracoscopic procedures. We aimed to determine the effect of lower insufflation pressures on patients’ surrogate markers for CO2 absorption.Methods
Following institutional audit approval, we collected and analysed intraoperative data from patients up to 6 months of age undergoing thoracoscopic repair of congenital diaphragmatic hernia (CDH) or oesophageal atresia (OA). Arterial CO2, end tidal CO2 and pH served as surrogate markers for CO2 absorption. We determined 2 patient cohorts; patients in the historic cohort (HC) were operated between 2007 and 2012 using insufflation pressures between 5 and 10mmHg, patients in the low pressure cohort (LPC) were operated between 2013 and 2017 aiming not to exceed insufflation pressures of 6mmHg after establishing pneumothorax.Results
There were 20 patients in the low pressure cohort (9 CDH, 11 OA), the historic cohort included 21 patients (16 CDH, 5 OA, p=0.6). While intraoperative pH was similar in both groups, peak arterial CO2 pressure (PaCO2) was lower in the LPC than in the HC (median of 12.5 vs 11.2, p=0.05) (Figure 1). Peak end tidal CO2 tended to be lower in the LPC than in the HC (p=0.13). Mean operating times in the LPC were significantly longer with 222 minutes compared to 145 minutes in the HC (p=0.001), possibly reflecting the higher number of OA in the LPC.Conclusion
Our data suggest that lower insufflation pressures during thoracoscopy in infants up to 6 months may correlate with lower CO2-absorption during thoracoscopy. Multivariate analysis on a larger patient cohort is necessary to discriminate the effects of insufflation pressure, underlying diagnosis and operating time.