Experimental intra-abdominal hypertension attenuates the benefit of positive end-expiratory pressure in ventilating effusion-compressed lungs*.
OBJECTIVE
To test the ability of positive end-expiratory pressure to offset the reduction of resting lung volume caused by intra abdominal hypertension, unilateral pleural effusion, and their combination.


METHODS
: Controlled application of intrapleural fluid, raised abdominal pressure and their combination before and after positive end-expiratory pressure in an anesthetized porcine model of controlled ventilation.


METHODS
Large animal laboratory of a university-affiliated hospital.


METHODS
Fourteen deeply anesthetized swine (weight 30-35 kg).


METHODS
Unilateral pleural effusion instillation (13 mL/kg), intra-abdominal hypertension (15 mm Hg), and simultaneous pleural effusion/intra abdominal hypertension.


METHODS
Tidal compliance, end-expiratory lung aeration by gas dilution functional residual capacity, and quantitative analyses of computerized tomograms of the lungs at the extremes of the tidal cycle.


RESULTS
Positive end-expiratory pressure of 10 cm H2O (positive end-expiratory pressure 10) increased mean functional residual capacity by 368 mL when pleural effusion was present and by 184 mL when intra-abdominal hypertension was present. When pleural effusion and intra-abdominal hypertension were simultaneously applied, positive end-expiratory pressure 10 failed to improve tidal compliance and increased functional residual capacity by only 77 mL, whereastidal recruitment during ventilation remained substantial.


CONCLUSIONS
The presence of intra-abdominal hypertension negates most of the positive end-expiratory pressure 10 benefit in reversing pleural effusion-induced de-recruitment. Relief of intra-abdominal hypertension may be instrumental to the treatment of pleural effusion-associated lung restriction and cyclical tidal collapse and reopening.
Regions Hosptial, St Paul, MN, USA.
Paolo
P
Formenti
Jeronimo
J
Graf
Gustavo A
GA
Cortes
Katherine
K
Faltesek
Kenneth
K
Gard
Alexander B
AB
Adams
Joseph
J
Tashjian
David J
DJ
Dries
John J
JJ
Marini
D000818:Animals; D005652:Functional Residual Capacity; D059325:Intra-Abdominal Hypertension / Q000150:complications*; D008168:Lung / Q000000981:diagnostic imaging; D023421:Models, Animal; D010996:Pleural Effusion / Q000150:complications* / Q000628:therapy*; D011175:Positive-Pressure Respiration; D013552:Swine; D013990:Tidal Volume; D014057:Tomography, X-Ray Computed