Crash and occupant predictors of pulmonary contusion

Pulmonary contusions (PCs) are a common injury sustained in motor vehicle collisions. The crash and occupant characteristics of PC in motor vehicle collisions are currently unknown. Additionally, the clinical significance and the impact on mortality have not been determined.

A retrospective review of the Crash Injury Research and Engineering Network database with inclusion criteria of frontal (F) and near-side lateral (L) crashes involving occupants older than 15 years, yielded 2,184 case occupants. Pearson's chi and multivariate logistic regression were used with a p < 0.05 conferring statistical significance.

Median age was 38 years, 80% were drivers and mortality was 16%. Forty-nine percent of case occupants were not wearing lap-shoulder belts. Chest trauma was sustained by 1,131 (52%), of whom 379 had PC. Crash characteristics included: 38 kph median change in velocity (delta V), 72% frontal deformation, and 35% struck a fixed object. Injury characteristics included median Injury Severity Score 17 with the following Abbreviated Injury Score (AIS) >2 injuries: thoracic 40%, abdominal 19%, and head 24%. Univariate predictors of PC included: age <25, male, higher Injury Severity Score, fatality, delta V >45 kph, L impacts, and collision with fixed object. PC was significantly associated with occupant compartment intrusion in F but not L crashes. In multivariate analysis, significant predictors of PC included: age <25 (odds ratios [OR] = 1.5), delta V >45 kph (OR = 1.9), and fixed object (frontal crash only) (OR = 1.8). Controlling for head, spine, abdominal, and extremity injuries AIS >2, PC was not a statistically significant risk factor for mortality. This was consistent whether or not another AIS >2 thoracic injury was present. The effectiveness of side-impact airbags was not evaluated due to the small sample size.

Crash severity as demonstrated by higher delta V was strongly associated with PC in all crashes. Frontal crashes with a fixed object or intrusion are more likely to result in a PC. The risk of PC is greatly increased in near-side lateral impacts regardless of intrusion or object struck; suggesting occupant proximity may be the most important factor. Further investigations of the efficacy of side airbags as a counter measure should be considered and continued public education of the efficacy of lap-shoulder restrains should continue. Unexpectedly, although a marker for crash severity, PC is not an independent marker of mortality.