Effects of positive end-expiratory pressure on respiratory function and hemodynamics in patients with acute respiratory failure with and without intra-abdominal hypertension: a pilot study.
BACKGROUND
To investigate the effects of positive end-expiratory pressure (PEEP) on respiratory function and hemodynamics in patients with acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) with normal intra-abdominal pressure (IAP < 12 mmHg) and with intra-abdominal hypertension (IAH, defined as IAP >or= 12 mmHg) during lung protective ventilation and a decremental PEEP, a prospective, observational clinical pilot study was performed.


METHODS
Twenty patients with ALI/ARDS with normal IAP or IAH treated in the surgical intensive care unit in a university hospital were studied. The mean IAP in patients with IAH and normal IAP was 16 +/- 3 mmHg and 8 +/- 3 mmHg, respectively (P < 0.001). At different PEEP levels (5, 10, 15, 20 cmH2O) we measured respiratory mechanics, partitioned into its lung and chest wall components, alveolar recruitment, gas-exchange, hemodynamics, extravascular lung water index (EVLWI) and intrathoracic blood volume index (ITBVI).


RESULTS
We found that ALI/ARDS patients with IAH, as compared to those with normal IAP, were characterized by: a) no differences in gas-exchange, respiratory mechanics, partitioned into its lung and chest wall components, as well as hemodynamics and EVLWI/ITBVI; b) decreased elastance of the respiratory system and the lung, but no differences in alveolar recruitment and oxygenation or hemodynamics, when PEEP was increased at 10 and 15cmH2O; c) at higher levels of PEEP, EVLWI was lower in ALI/ARDS patients with IAH as compared with those with normal IAP.


CONCLUSIONS
IAH, within the limits of IAP measured in the present study, does not affect interpretation of respiratory mechanics, alveolar recruitment and hemodynamics.
Department of Anesthesiology and Critical Care Medicine, University Hospital Mannheim, Faculty of Medicine, University of Heidelberg, Mannheim, Germany, Theodor-Kutzer Ufer, Mannheim, 68165, Germany. joerg.krebs@umm.de.
Joerg
J
Krebs
Paolo
P
Pelosi
Charalambos
C
Tsagogiorgas
Markus
M
Alb
Thomas
T
Luecke
D000005:Abdomen / Q000503:physiopathology*; D055371:Acute Lung Injury / Q000503:physiopathology* / Q000628:therapy; D000368:Aged; D003161:Compartment Syndromes; D005260:Female; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D006973:Hypertension / Q000175:diagnosis / Q000503:physiopathology*; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D019370:Observation; D010865:Pilot Projects; D011175:Positive-Pressure Respiration; D011446:Prospective Studies; D012128:Respiratory Distress Syndrome / Q000503:physiopathology* / Q000628:therapy; D015656:Respiratory Mechanics / Q000502:physiology; D012143:Respiratory Physiological Phenomena