End‐expiratory lung volume assessment using helium and carbon dioxide in an experimental model of pediatric capnoperitoneum

Abstract

Background Capnoperitoneum during laparoscopy leads to cranial shift of the diaphragm, loss in lung volume and risk of impairedgas exchange. Infants are susceptible to these changes and bedside assessment of lung volume during laparoscopy might assist with optimizing the ventilation. Thus, the primary aim was to investigate the monitoring value of a continuous end‐expiratory lung volume (EELV) assessment methodbased on CO₂ dynamics (EELV_CO2)in a pediatric capnoperitoneummodel by evaluating the correlation and trending ability against heliumwashout (EELV_He). Methods Intra‐abdominal pressure (IAP) was randomly varied between 0, 6 and 12 mmHg with CO₂ insufflation, while positive end‐expiratory pressure (PEEP) levels of 3, 6 and 9 cmH₂O were randomly applied in eight anesthetized and mechanically ventilated chinchilla rabbits. Concomitant EELV_CO2 and EELV_Heand lung clearance index (LCI) were obtained under each experimental condition. Results Significant correlations were found between EELV_CO2 and EELV_Hebefore capnoperitoneum (r=0.85, pCO2 and EELV_He and resulted in 100% concordance rate between the methods regarding changes in lung volume. EELV_He and LCIshowed a curvilinear relationship, and an EELV_He of approximately 20mlkg^‐1, determined with a receiver operating characteristic curve, was associated with near‐normal LCI values. Conclusion In this animal model of pediatriccapnoperitoneum, reliable assessmentofchanges inEELV based on EELV_CO2 requires an open lung strategy, defined as EELV above approximately 20 mlkg^‐1.