Submitted on May 18, 2006
Accepted on June 7, 2007
Ventilation-perfusion Relationships Following Experimental Pulmonary Contusion
Andriy I Batchinsky1*, William B Weiss2, Bryan S Jordan3, Edward J. Dick4, David A Cancelada5, and Leopoldo C Cancio6
1 Laboratory Division, US Army institute of Surgical Research, Fort Sam Houston , Texas, United States
2 Department of Surgery, Blanchfield Army Community Hospital, Fort Campbell, Kentucky, United States
3 Laboratory Division, US Army institute of Surgical Research, Fort Sam Houston , Texas, United States; Fort Sam Houston, Texas, United States
4 Southwest Foundation for Biomedical Research, San Antonio, Texas, United States
5 Department of Surgery, William Beaumont Army Medical Center, El Paso, Texas, United States
6 Trauma Division, US Army Institute of Surgical Research, Fort Sam Houston, Texas, United States
* To whom correspondence should be addressed. E-mail: andriy.batchinsky{at}amedd.army.mil.
Ventilation-perfusion changes after right-sided pulmonary contusion (PC) in swine were investigated using the multiple inert gas elimination technique (MIGET). Methods: Anesthetized swine (injury, n=8, control n=6) sustained a right-chest PC by a captive-bolt apparatus. This was followed by a 12 ml/kg hemorrhage, resuscitation and re-infusion of shed blood. MIGET and thoracic computed tomography (CT) were performed before and 6 h after injury. Three-dimensional CT scan reconstruction enabled determination of the combined fractional volume of poorly aerated and non-aerated lung tissue (VOL), and the mean gray-scale density (MGSD). Results: 6 hours after PC, PaO2 decreased from 234.9±5.1 to 113.9±13.0. Shunt (QS) increased (2.7±0.4 to 12.3±2.2%) at the expense of blood flow to normal V/Q compartments which decreased from 97.1±0.4 to 87.4±2.2%). Dead space ventilation (VD/VT) increased (58.7±1.7% to 67.2±1.2%). MGSD increased (-696.7±6.1 to -565.0±24.3 Hounsfield units), as did VOL (4.3±0.5 to 33.5±3.2%). Multivariate linear regression of MGSD, VOL, VD/VT, and QS vs. PaO2 retained VOL and QS (r2=.835) as independent covariates of PaO2. Conclusions: An increase in QS characterizes lung failure 6 h after pulmonary contusion; QS and VOL correlate independently with PaO2.
