brandenjeromeaxel

By academic.oup.com

Venous thromboembolism is common after major trauma (>50%) and fatality from pulmonary embolism (PE) approaches 50% in some series.1 The incidence of symptomatic PE after major trauma varies and is very dependent on how the diagnosis is confirmed and probably under-reported in cases of sudden death without an autopsy.2

Evidence suggests that pneumatic lower limb compression devices and low-dose s.c. unfractionated heparin (UFH) prophylaxis are not completely effective in preventing venous thromboembolism.3 Low-molecular-weight heparin (LMWH) is more efficacious than UFH, and although there was no difference in major bleeding in those patients without obvious contraindication, the clinical concern about excessive haemorrhage persists. As such, retrievable inferior vena cava (IVC) filters have been increasingly used in many trauma patients.4,5 The IVC filters are, however, expensive, invasive, and associated with some complications, including erosion of the IVC, inducing thrombosis either above or below the filter, migration of the filter to the right atrium, and tilting or mal-positioning of the filter resulting in ineffective filtering of emboli and fatal PE.6–8 Although IVC filters are now widely used in many trauma patients,9 evidence to support their cost-effectiveness from randomized controlled trials or meta-analyses is sparse.

Fatal PE is an important outcome after major trauma.1 It has been reported to occur at a frequency between 0.4% and 4.2% after major trauma.3,12,13 It is possible that fatal PE occurs more often in patients who have more severe traumatic injuries and some of these patients may die with PE instead of from PE. If most deaths related to PE after major trauma are in fact preventable and the risk factors for this fatal condition can also be identified, selecting high-risk patients for invasive preventive therapy such as IVC filters will be most appropriate. The most appropriate time to insert and remove a retrievable IVC filter in patients after major trauma is also uncertain.

We hypothesized that fatal PE after major trauma is preventable and may be predictable from the characteristics of patients and conducted a nested cohort study to assess its incidence, time of occurrence, and risk factors in a consecutive cohort of major trauma patients who did not receive IVC filters.

Methods

After obtaining approval from the Confidential Health Information Committee and hospital ethics committee, the clinical data of all major trauma patients who were admitted to the Intensive Care Unit of Royal Perth Hospital in Western Australia, between 1994 and 2002, were linked to the trauma registry, death registry, and state hospital morbidity databases. This study period was chosen because IVC filters and routine duplex-Doppler ultrasonography were not used for the trauma patients during the study period. Information on the precise causes of death and on the use of UFH prophylaxis before death were obtained from the Coroner's post-mortem reports and hospital notes, respectively. Royal Perth Hospital is a tertiary hospital in Western Australia and is the state's designated trauma centre. In this study centre, all deaths related to major trauma were referred to the Coroner's office for post-mortem examination to determine the cause(s) of death.

Statistical analysis

The data analysed included patients' age, sex, severity of injury as measured by Acute Physiology and Chronic Health Evaluation [APACHE],17 Injury Severity Score, and details of the severity of head injuries including computed tomographic (CT) findings of the brain,18 Charlson's co-morbidity index,19 interventions such as intracranial pressure monitor, pattern of injuries, the use of s.c. UFH prophylaxis, and BMI.

Categorical variables were analysed by χ2 test, and continuous variables with a near normal distribution and variables with skewed distributions [standard deviation (sd) >50% mean] were analysed by t-test and the Mann–Whitney test, respectively. Multivariate logistic regression was used to assess the associations between multiple predictors and risk of fatal PE. The predicted risk of death of each patient in this cohort was estimated by a combination of the APACHE II-predicted mortality, Injury Severity Score, and details of the severity of head injuries such as pupillary response to light, motor response, and CT findings of the brain.

Attributable mortality of PE was estimated by the difference in the predicted risk of death between those who died from PE and other causes. We used a four-knot restricted cubic spline function, a technique very similar to polynomial function, to allow non-linearity of continuous predictors in the multivariate analysis.20 All statistical tests were performed by SPSS (version 13.0, IL, USA) and S-Plus (version 8.0, Insightful Corp., Seattle, WA, USA) and P-value <0.05 was regarded as significant.

Results

Of the 971 consecutive major trauma patients included in the study, 134 patients (13.8%) died during their hospital stay after the injury. Fatal PE accounted for a total of 16 deaths [11.9%, 95% confidence interval (CI) 8–19%] despite s.c. UFH being used in 44% of these patients. LMWH was not used in this cohort of patients. One other patient also had a small subsegmental PE in the post-mortem examination, but the PE was judged not to be the cause of death by the Coroner. Most patients with fatal PE were treated as having deteriorating sepsis, without considering PE as a diagnosis, before they died. The incidence of fatal PE in the whole cohort was about 1.6% (95% CI 1.0–2.7%; Fig. 1). The median time of fatal PE after the injury was 18 days [mean 39, inter-quartile range (IQR) 9–28] which was much later than other causes of death (median 2, mean 7, IQR 2–5; Fig. 2). The other main causes of death were severe traumatic brain injury, uncontrolled haemorrhage from multiple injuries, and infection leading to multiple organ failure.

Source: https://academic.oup.com/bja/article/105/5/596/234488/Incidence-and-risk-factors-for-fatal-pulmonary