Effect of body positioning on intra-abdominal pressure measurement and prognosis in critically ill patients
伊敏1 BAI Yu, ZHU Xi1
北京大学第三医院危重医学科
Background The current literatures confirm the widespread and frequent development of both intra abdominal hypertension (IAH) and abdominal compartment syndrome (ACS) among the critically ill with a significant associated risk of organ failure and increased mortality. The occurrence of intra abdominal hypertension (IAH) during the intensive care unit stay was an independent outcome predictor. The Consensus Conference proposes intra-abdominal pressure (IAP) should be measured in the complete supine position, However, the supine position of ICU patients (＜30° of bed increase) presents a significant risk factor for ventilator-associated pneumonia. The potential contribution of head of bed (HOB) position in elevating IAP should be considered. The purpose of this study was to evaluate the effect of body positioning on intra-abdominal pressure measurement and the effect of IAP at different body positioning on prognosis in critically ill patients.
Methods A prospective, cohort study to investigate the effect of patient positioning on IAP and prognosis was conducted on critically ill patients admitted to a medical–surgical intensive care unit (ICU). On admission, epidemiologic data and risk factors for intra-abdominal hypertension were studied; then, daily maximal intra-abdominal pressures (IAPmax), abdominal perfusion pressure, filtration gradient, Acute Physiology and Chronic Health Evaluation (APACHE) II score and sequential organ failure assessment (SOFA) score, were registered. IAPs were recorded through a bladder catheter every 4 hrs in first day. IAP was measured in a range of patient HOB increases from 0° to 45°. Intra-abdominal hypertension was defined as IAP >12 mm Hg. Abdominal compartment syndrome was defined as IAP >20 mm Hg plus >1 new organ failure. Main outcome measure was hospital mortality.
Results The main results of this study are the high incidence of IAH (27.8%) in a prospective cohort of consecutive ICU patients; a significant and independent relationship between IAP and HOB increases. Considering the absolute numbers of IAP, the differences for 10° and 20° were small, whereas the differences for 30° and 45° become clinically relevant; APACHE II and SOFA scores, abdominal perfusion pressure (APP) and filtration gradient (FG) ateach body position differed significantly between survivors and non-survivors; length of mechanical ventilation, length of ICU stay, APACHE II,SOFA scores, APP and FG at HOB increases of 30° and 45° differed significantly between MODS group and Non-MODS group; there are significant correlations between APP or FG and APACHE II, SOFA, Length of Mechanical ventilation, Length of ICU stay.
Conclusions Our study expands previous knowledge in several ways. First, it provides a prospective, well-documented approach to the epidemiology and the risk factor of IAH in a heterogeneous ICU population. Second, there is a significant and independent relationship between IAP and HOB positioning in critically ill patients, whereas the differences for 30° and 45° become clinically relevant. Third, APP and FG are associated with a higher rate of multiple organ failure and mortality. The potential contribution of body position in elevating IAP should be considered in patients with the risk factor for IAH and ACS in critically ill patients
