Lung complications are common in intensive care treated patients with pelvis fractures: a retrospective cohort study

Respiratory complications are common after major trauma and one of the most serious forms is acute respiratory distress syndrome (ARDS) with an incidence of 12–25 % [1, 2]. ARDS is defined as an acute inflammatory pulmonary condition with hypoxemia combined with bilateral lung infiltrates seen with computed tomography or x-ray. The cause should be an inciting insult such as sepsis, major surgery or trauma [3]. Risk factors for developing ARDS in trauma are injury severity score (ISS), pulmonary contusions [4, 5], blunt injury mechanism, flail chest [5] and massive transfusion [5, 6]. It is well recognized that pelvis fractures are associated with respiratory failure including ARDS [5, 7, 8]. Theoretically, respiratory failure could be aggravated by a “second hit” such as an inflammatory response induced by a surgical procedure. Therefore, surgical fixations in patients with pelvis fractures have sometimes been postponed in patients due to this reason. There are clear indications that early fixation reduces respiratory complications in patients both with femur- and pelvis fractures [9, 10]. However, whether the surgical procedure per se is associated with deterioration in lung function has to our knowledge, not been studied in patients with pelvis fractures. Moreover, although it is well known that intensive care treated patients with pelvis fractures often have respiratory complications, it has not been studied whether these specifically are associated with worse outcome [10]. Indeed, morbidity and mortality in ARDS caused by trauma is much lower than for other underlying conditions. Thus, mortality in a mixed intensive care unit (ICU) population with ARDS is 30 – 45 % [1, 11‐13], but in trauma patients with ARDS the mortality is 9 – 25 % [2, 14]. In addition, the incidence of severe respiratory complications in a European cohort of patients with pelvis fractures needing intensive care have not, what we are aware of, been studied. Therefore the pre-specified aims of this registry study were to 1) assess the incidence of severe respiratory complications, i.e., ARDS or severe hypoxemic failure (AHF, as defined as ARDS without radiological criteria or when no radiologic examination was performed) in patients with pelvis fractures in our ICU (the hospital is a referral center for pelvis fractures), 2) whether the surgical intervention in these patients is associated with worsening of the pulmonary condition and 3) whether the lung complications is associated with mortality. The hypotheses were that ARDS/AHF 1) is common in ICU treated patients with pelvis fractures, 2) will not be related to surgical stabilization, or 3) to mortality.

The study was approved by the local ethics committee at Uppsala University (2006/140), Uppsala, Sweden and the study was registered at ISRCTN.org number, ISRCTN10335587. Informed consent was obtained from the patient before inclusion in the database.

Data was used from a cohort of 669 patients admitted to the Uppsala University Hospital scheduled for surgical stabilization of pelvis ring and/or acetabulum fractures. Except the patients in the local region of the Uppsala University Hospital, 30 additional hospitals referred patients after providing primary care.

One hundred and twelve patients, 29 women and 83 men were enrolled in this study. General characteristics are presented in Table 1.

The mechanism of injury is presented in Fig. 2. Motor-vehicle accidents were the most common cause followed by falls. In 16 patients (15 falls and 1 motor vehicle accident), the trauma was related to a suicide attempt.

In this retrospective study analyzing 112 patients treated in a referral center ICU of a cohort of 669 patients with pelvis fractures, we found that 1) 67 % of the ICU treated patients had severe respiratory failure, 2) 23 of the ICU treated patients developed severe respiratory failure during the surgical stabilization and 3) the respiratory failure did not contribute to mortality.

The database analyzed contains all patients with pelvis fractures referred to our center. Thus, we consider that the database used is complete. However, the data regarding respiratory complications including blood gas analyses, chest radiography and ventilator settings were retrospectively collected and documented in our files. Therefore, the oxygenation parameters were not always obtained at the exact same time point as the chest radiograms. Moreover, in some instances, chest radiography was not performed and therefore it was not possible to diagnose whether the patient had ARDS. Furthermore, if we had performed more CT-scans that have a higher diagnostic sensitivity and specificity would also have modified the number of ARDS diagnosed in this study. Hence, although the total number of severe respiratory failure is correct, some of the patients now diagnosed as AHF could therefore have ARDS. In this context, it is important to recognize that one-sided pulmonary infiltrates are not consistent with a diagnosis of ARDS, and in fact, many of the patients had one-sided lung changes.

Compared with other studies the incidence of respiratory failure including ARDS in patients with pelvis fractures may seem high. However, we analyzed only the patients treated in the ICU. If one uses as denominator the whole cohort of patients referred or treated at our hospital, the incidence of severe respiratory failure will be 11 % and of ARDS 4 %. These numbers agree with other studies in unselected material that have reported an incidence of ARDS between 1.5 and 23 % [10, 16, 17].

We found that lung contusion was associated with a development of respiratory failure in relation to the surgical stabilization. Although our results cannot pinpoint whether the deterioration in lung function occurred during of after surgery, this finding is in line with Pape et al. [18] who found that nailing of femur fractures in patients with severe chest trauma was associated with a 33 % incidence of ARDS. Likewise, Hoyt et al. [19] found a higher incidence of ARDS in patients with chest trauma (20 % compared with 3.3 %). We think that it is important to consider not only the surgical procedure that can be “a second hit” and deteriorate the lung function. In addition, anesthesia and the ventilatory management are important factors in this context. In fact, it is found that inappropriate ventilation during surgery increases post-operative respiratory complications [20]. In neither of these studies, it is reported whether lung protective ventilation was used. However, Schreiter et al. [21] have shown that lung complications in patients with lung contusion can be reduced with protective ventilation including low tidal volumes, lung recruitment and adequate PEEP. Also, in our study lung recruitment maneuvers or adequately high PEEP were not used routinely. Therefore, we believe that a protective ventilatory management during the surgical stabilization could have reduced the high incidence of new respiratory failure in our study.

In contrast to most other studies [9, 10, 16, 17], early surgical stabilization was associated with development of new respiratory failure. This finding must be interpreted with caution; except what we discussed above regarding the higher incidence of lung contusion in these patients, this finding can be due only by chance since we did not a priori have this as an outcome parameter. Furthermore, it could be so that respiratory effect of lung contusion developed by time independent of the surgical procedure. In the patients, who were operated on later, the lung function did not in most cases deteriorate and even in many incidences improve. The latter finding could be due to that the orthopedic surgeon might have delayed the surgical stabilization because of an initial serious lung condition until the lungs had improved. Thus, whether the same results had been obtained if the surgery had been performed earlier is unknown.

We found that the mortality rate is low in patients with pelvis fractures in agreement with other studies [16, 17]. Although there were five patients who died in the AHF/ARDS group compared with none in the group without respiratory failure, in no case it could be found that the respiratory condition was a clear contributing factor. This finding agree with Treggiari et al. [2], who found, that after adjusting for age, ISS and acute physiological score (APS) there was no association of mortality with ARDS in critically ill trauma patients. Thus, we consider that the respiratory failure is manageable and is not an important cause of death in this patient category.

In conclusion, we found that the incidence of acute respiratory failure in ICU treated patients with pelvis fractures was high and that overall no significant change in lung function in occurred in relation to surgical stabilization. However, in patients with lung contusion this study indicated that surgical stabilization was associated with a deterioration in lung function. Furthermore, we found, that mortality was low and was probably not related to the respiratory condition.