Repeated generation of the pulmonary pressure-volume curve may lead to derecruitment in experimental lung injury.
OBJECTIVE
Measurements from the pulmonary pressure-volume (PV) curve have been proposed to adjust ventilator settings. We investigated the effects of repeated construction of an inflation PV curve implemented in a standard ventilator on recruitment or derecruitment in acutely injured lungs.


METHODS
Prospective experimental animal study in eight anesthetized and mechanically ventilated pigs.


METHODS
Acute lung injury was induced by lung lavage and animals were ventilated in volume controlled mode with PEEP 10 cmH(2)O. The PV curve was constructed five times repeatedly by constant pressure rise, after which ventilation with the preset PEEP was resumed immediately. Studies of hemodynamics, lung mechanics, blood gases and computed tomography were carried out before and after maneuvers.


RESULTS
Derecruitment was assessed as an increase in nonaerated lung volume (V(NON)), and V(PEEP) was the end-expiratory volume difference between PEEP and ZEEP. There was a significant decrease in PaO(2) from 90.4+/-33.3 to 70.9+/-36.3 mmHg and a rise in venous admixture from 47.8+/-12.7 to 59.1+/-16.6%. V(PEEP) was reduced from 244 to 202 ml. A corresponding decrease in normally aerated lung volume was observed, while regression analysis revealed increase in V(NON) depending on the amount of preexisting atelectasis.


CONCLUSIONS
Repeated generation of the PV curve with a readily available tool resulted in worsened oxygenation. Derecruitment of the lungs occurred with loss of PEEP at the start of the maneuver, which could not be recovered by a maximum inflation pressure of 40 cmH(2)O. Repeated use of the investigated tool should be cautioned, and users should consider measures to preserve aerated lung volumes.
Henzler
Dietrich
D
Department of Anesthesiology, Aachen University Hospital, Pauwelsstrasse 30, 52074 Aachen, Germany. mail@d-henzler.de
Mahnken
Andreas
A
Dembinski
Rolf
R
Waskowiak
Britta
B
Rossaint
Rolf
R
Kuhlen
Ralf
R
D000818:Animals; D001784:Blood Gas Analysis; D018893:Bronchoalveolar Lavage; D005260:Female; D006439:Hemodynamics / Q000502:physiology; D008168:Lung / Q000000981:diagnostic imaging; D055370:Lung Injury; D008176:Lung Volume Measurements; D011175:Positive-Pressure Respiration; D011312:Pressure; D011446:Prospective Studies; D011659:Pulmonary Gas Exchange / Q000502:physiology; D012044:Regression Analysis; D015656:Respiratory Mechanics / Q000502:physiology*; D018709:Statistics, Nonparametric; D013552:Swine; D014057:Tomography, X-Ray Computed