EditorialThe saga continues: How to set best PEEP in intra-abdominal hypertension?
Section snippets
Historical Perspective
Critically ill patients admitted to a general intensive care unit (ICU) will develop intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS) in around 30% and 5% respectively [1]. If sustained, IAH causes increased morbidity and mortality [1]. Previous data showed that IAH is associated with ventilator-induced lung injury, alterations with regard to lung distension, lung recruitment and lung edema [2]. Fig. 1 summarises the deleterious effects on respiratory function caused
Animal Data
Animal data have suggested that PEEP levels should be adjusted to counteract the effects of raised IAP as this may prevent IAH-induced respiratory dysfunction. A study in 13 pigs with healthy lungs and IAH created by an inflatable balloon with unmatched PEEP showed that PEEP below IAP level cannot prevent forced residual capacity (FRC) decline [9]. In this study, the authors randomised three levels of IAP (3 mm Hg (baseline), 18 mm Hg, and 26 mm Hg) and four commonly applied levels of PEEP (5, 8, 12
Human Data
The present study is not unique, as the first human data goes back to 1998 in a pilot study of 7 patients with ARDS (6 having secondary ARDS) and raised IAP (14.4 ± 4.4 mm Hg at baseline) in whom simple PEEP-adjustment (in cmH2O) for IAP (in mm Hg) was performed [12]. The IAP was measured at zero PEEP via the standard bladder technique [13]. PEEP-application resulted in a significant better oxygenation with an increase in P/F ratio from 101.9 ± 35.4 to 251.7 ± 107 after 1 week. Peak, plateau and mean
Importance of abdomino-thoracic index of transmission
Previous studies have shown that the average abdomino-thoracic index of transmission (ATI) is around 50%, meaning that for each 1 mm Hg pressure increase in IAP approximately 0.5 mm Hg or thus 0.7 cmH2O is transmitted to the thoracic compartment. Off course, the actual ATI will depend on actions of the rib cage, the diaphragm, the chest wall, the abdominal muscles and the compliance of both the chest wall and the abdominal wall [18], [19], [20], [21]. Other studies and guidelines, therefore,
Limitations and future perspectives
The authors have to be congratulated for having performed this excellent study, and the limitations are nicely addressed. First, the number of patients (n = 15) included in this pilot study was small, moreover due to the fact that 5 out of 15 patients did not tolerate well the high PEEP-levels not all data could be analysed. Second, only 1 out of 15 patients had ARDS and as stated above lung injury influences the effects of IAH and PEEP on oxygenation and respiratory mechanics. Likely the effect
Acknowledgements and COI
Manu Malbrain is founding President of WSACS (The Abdominal Compartment Society) and current Treasurer, he is also member of the medical advisory Board of Pulsion Medical Systems (part of Maquet Getinge group) and consults for ConvaTec, Acelity, Spiegelberg and Holtech Medical. He is co-founder of the International Fluid Academy (IFA). The mission statement of the IFA is to foster education, promote research on fluid management and hemodynamic monitoring, and thereby improve survival of
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