End-expiratory lung impedance as a tool for PEEP optimization in patients with intra-abdominal hypertension: a laparoscopic surgery model

Increased intra-abdominal pressure (IAP) that is frequently found on patients requiring mechanical ventilation in the intensive care unit (ICU) can disrupt splanchnic perfusion and ventilation management. Elevated IAP, resulting from various factors including hemorrhage or abdominal masses, can lead to multi-organ dysfunction if not managed effectively. Interestingly, IAP is also prevalent in healthy individuals undergoing laparoscopic surgery, making it a valuable model for studying ventilation strategies applicable to critically ill patients. This study investigates the effects of varying positive end-expiratory pressure (PEEP) levels on end-expiratory lung impedance (EELI) during laparoscopic procedures, hypothesizing that alterations in PEEP can significantly influence EELI, particularly in dependent lung regions. Conducted at Cipto Mangunkusumo Hospital, this prospective cohort study included adult patients without severe pulmonary or cardiovascular conditions, assessing EELI through electrical impedance tomography (EIT). EIT was used to assess global and regional EELI changes at PEEP levels of 5, 8 11 and 14 cmH2O following CO2 insufflation. The findings indicated that insufflation raised global EELI (Delta EELI-G) following PEEP adjustments, which contradicts expectations from increased IAP. Regional analysis highlighted that dependent lung areas exhibited more significant changes, suggesting a complex relationship between PEEP and lung mechanics during elevated IAP. Despite no adverse respiratory complications observed, obesity notably influenced EELI post-anesthesia, underscoring the necessity for tailored PEEP strategies to enhance pulmonary function in at-risk populations. This study advances understanding of optimal ventilatory management in patients with altered IAP and calls for further investigation into individualized PEEP applications and the exploration of advanced imaging modalities for lung assessment.