RESPIRATORY CARE Paper in Press. Published on March 13, 2018 as DOI: 10.4187/respcare.05952 Pulmonary Contusion in Mechanically Ventilated Subjects After Severe Trauma Sakshi Mathur Dhar MD, Matthew D Breite MD, Stephen L Barnes MD, and Jacob A Quick MD BACKGROUND: Pulmonary contusions are thought to worsen outcomes. We aimed to evaluate the effects of pulmonary contusion on mechanically ventilated trauma subjects with severe thoracic injuries and hypothesized that contusion would not increase morbidity. METHODS: We conducted a single-center, retrospective review of 163 severely injured trauma subjects (injury severity score > 15) with severe thoracic injury (chest abbreviated injury score > 3), who required mechanical ventilation for >24 h at a verified Level 1 trauma center. Subject data were analyzed for those with radiographic documentation of pulmonary contusion and those without. Statistical analysis was performed to determine the effects of coexisting pulmonary contusion in severe thoracic trauma. RESULTS: Pulmonary contusion was present in 91 subjects (55.8%), whereas 72 (44.2%) did not and mean (53. ؍ have pulmonary contusions. Mean chest abbreviated injury score (3.54 vs 3.47, P were similar. There was no difference in mortality (11 (12. ؍ injury severity score (32.6 vs 30.2, P Frequency of .(60. ؍ vs 9 [12.5%], P > .99) or length of stay (16.29 d vs 17.29 d, P [12.1%] Subjects with .(75. ؍ ventilator-associated pneumonia was comparable (43 [47.3%] vs 32 [44.4%], P contusions were more likely to grow methicillin-sensitive Staphylococcus aureus in culture (33 vs 10, :CONCLUSIONS .(003. ؍ as opposed to Pseudomonas aeruginosa in culture (6 vs 13, P (004. ؍ P Overall, no significant differences were noted in mortality, length of stay, or pneumonia rates between severely injured trauma subjects with and without pulmonary contusions. Key words: ventilator-associated pneumonia; trauma; pulmonary contusion; outcomes; thoracic; ARDS. [Respir Care 0;0(0):1–•. © 0 Daedalus Enterprises] Introduction rax. Rib fractures and their degree of displacement, as well as flail chest and penetrating mechanisms, all contribute to Pulmonary contusions range from mild to life-threaten- severity of the underlying lung injury.1-3 ing injury. Commonly diagnosed in patients who suffer Shear forces associated with the development of pulmo- blunt chest trauma, the incidence in these populations nary contusions cause several local and systemic effects. reaches 65%. Pediatric patients have an even higher rate of Mucus production is increased. Oxygen radicals and cyto- significant lung injury of up to 80%, secondary to in- kines are released. Protein accumulates, and surfactant pro- creased chestwall compliance.1 Isolated pulmonary contu- duction is reduced. The end result is atelectasis and consol- sion is rare, and often the rate of pulmonary contusion is idation. These mechanical and inflammatory sequelae have linearly associated with severity of injury to the bony tho- the propensity to complicate care of those with severe chest- wall injury, potentially increasing the risk of pneumonia, acute respiratory failure, and ARDS.4-6 The morbid sequelae of The authors are affiliated with the Division of Acute Care Surgery, pulmonary contusion are most often seen in those who have Department of Surgery, University of Missouri, Columbia, Missouri. failed conservative therapy and require mechanical ventila- 4,6,7 The authors have disclosed no conflicts of interest. tion to improve gas exchange and prevent hypoxemia. Mechanically ventilated patients are also at increased risk to Correspondence: Jacob A Quick MD, University of Missouri Department develop ventilator-associated events, such as barotrauma, vo- of Surgery, Division of Acute Care Surgery, 1 Hospital Drive, MC220, 4,8,9 Columbia, MO 65212. E-mail: [email protected]. lutrauma, and infectious complications. Prior studies have failed to isolate pulmonary contusion DOI: 10.4187/respcare.05952 as the causative agent of worsened outcomes among those RESPIRATORY CARE • ●●VOL ● NO ● 1 Copyright (C) 2018 Daedalus Enterprises ePub ahead of print papers have been peer-reviewed, accepted for publication, copy edited and proofread. However, this version may differ from the final published version in the online and print editions of RESPIRATORY CARE RESPIRATORY CARE Paper in Press. Published on March 13, 2018 as DOI: 10.4187/respcare.05952 PULMONARY CONTUSION IN MECHANICALLY VENTILATED SUBJECTS with severe injuries because of the prevalence of concur- rent traumatic injury.10 With severe thoracic injury, it is QUICK LOOK difficult to discern whether the unwanted sequelae are sec- Current knowledge ondary to thoracic injury or to the underlying lung injury Severe thoracic injury is often associated with pulmo- specifically. We sought to evaluate the outcomes of me- nary contusions. Direct pulmonary parenchymal injury chanically ventilated patients with severe thoracic injuries, can result in worsened overall lung function and create with and without pulmonary contusion, and hypothesized difficulties in management. In the trauma setting, the that contusion would not increase morbidity. presence of pulmonary contusions is thought to increase Methods the morbidity and mortality of injured patients. What this paper contributes to our knowledge A retrospective cohort study was undertaken at our in- stitution, an American College of Surgeons Level 1 trauma To identify the effect of pulmonary contusion on pa- center, following institutional review board approval. All tients with severe thoracic injury, we reviewed only consecutive trauma patients admitted over a 30-month pe- subjects who required mechanical ventilation, who also riod who required mechanical ventilation for Ͼ24 h were had elevated injury scores. Whereas we identified the evaluated. To ensure that severe injury was present, pa- potential to require advanced ventilator management in tients with a chest abbreviated injury score Ͻ 3 and injury the setting of pulmonary contusions, there appeared to severity score Ͻ 15 were excluded. The remaining sub- be no difference in morbidity, length of stay, or mor- jects were then divided into 2 groups for analysis: (1) tality between subjects suffering pulmonary contusion those with documented plain chest radiograph evidence of and those without. pulmonary contusion within 24 h of admission and (2) those without radiographic evidence of pulmonary contu- sion. We did not include patients with evidence of pulmo- nary contusion only seen on computed tomography exam- 91 subjects (55.8%), whereas 72 subjects (44.2%) did not inations, as these injuries are typically not clinically suffer pulmonary contusion. Mean ages were similar (44 y ϭ important.11,12 To obtain the radiographic diagnosis of con- vs 50 y, P .10), and a similar percentage of subjects tusion and decrease bias, all radiographs were interpreted were male (66 [73%] vs 52 [72%], P Ͼ .99) in each group. by a resident radiologist, faculty radiologist, and blinded There were no differences between preexisting comorbid attending acutecare surgeon. Radiographic diagnosis was status or smoking history between groups. Mean body 2 2 only obtained when all 3 evaluators were in agreement. mass indices (29.3 kg/m vs 32.5 kg/m , P ϭ .24) were Demographics, types of injury, length of hospital stay, similar for those with contusion and those without (Table operative data, comorbidities, intubation data, microbio- 1). Mean chest abbreviated injury score (3.54 vs 3.47, logic data, imaging, and laboratory data were analyzed. P ϭ .53) and mean injury severity score (32.6 vs 30.2, Ventilator-associated pneumonia (VAP) was diagnosed uti- P ϭ .12) were similar between the 2 groups. All other lizing clinical and microbiologic criteria. Clinical VAP abbreviated injury score areas did not statistically differ diagnosis required at least 3 of the following: new or pro- between groups, except for the abdomen abbreviated in- gressive infiltrate on chest radiograph; fever Ͼ 38.5°C; jury score (1.8 vs 1.1, P Ͻ .003, 95% CI Ϫ1.23 to Ϫ0.25), leukocytosis (Ͼ12,000) or leukopenia (Ͻ4,000); purulent which was higher in subjects with pulmonary contusion. tracheal secretions; and absence of post-traumatic or post- Hospital length of stay (16.3 d vs 17.3 d, P ϭ .60) was surgical causes for clinical findings. If clinical criteria were similar between groups. There was no difference in mor- met, diagnosis was confirmed microbiologically with Ͼ104 tality (11 [12.1%] vs 9 [12.5%], P Ͼ .99) or discharge colony-forming units of a single predominant organism disposition. obtained via bronchoalveolar lavage. Statistical analysis Surgical procedures, both in mean total number of op- was performed using 2-tailed Student t test, Fisher exact erations (2.11 vs 2.1, P ϭ .89) and type of operation, test, and chi-square formulas. Statistical significance was between the groups were not significantly different. Tra- set to 95% (P Ͻ .05). cheostomy rates were not statistically significant (41% vs 46%, P ϭ .33), nor was the duration of intubation with Results mechanical ventilation before tracheostomy (6.5 d vs 7.6 d, P ϭ .32). Mean total blood product transfusion amounts During the study period, 324 patients were admitted to (1,153 mL vs 827 mL, P ϭ .20) as well as daily fluid the trauma ICU and required mechanical ventilation for balances (ϩ669 mL vs ϩ627 mL, P ϭ .69) were similar Ͼ 24 h. After applying exclusion criteria, 163 subjects between those with contusion and those without. Mean remained for analysis. Pulmonary contusion was present in vital signs and laboratory results were similar between 2RESPIRATORY CARE • ●●VOL ● NO ● Copyright (C) 2018 Daedalus Enterprises ePub ahead of print papers have been peer-reviewed, accepted for publication, copy edited and proofread. However, this version may differ from the final published version in the online and print editions of RESPIRATORY CARE RESPIRATORY CARE Paper in Press. Published on March 13, 2018 as DOI: 10.4187/respcare.05952 PULMONARY CONTUSION IN MECHANICALLY VENTILATED SUBJECTS Table 1. Comorbid Status of Subjects Without and With Pulmonary (158 d [16.7%] vs 136 d [16.8%], P Ͼ .99).