The relationship of hemodynamic parameters with ۶-month mortality in trauma patients; a prospective cohort study

Background: Although the relationship between cardiovascular and respiratory parameters and mortality in trauma patients has been reported in studies, the findings have been contradictory in many cases. Therefore, the present study aimed to evaluate the relationship of systolic and diastolic blood pressures, heart and respiratory rates, arterial oxygen saturation and shock index with ۶-month mortality of trauma patients.Methods: In a prospective cohort study, vital signs of the trauma patients presenting to emergency department were evaluated on admission. The patients were followed for ۶ months and mortalities were recorded. Finally, using stepwise multivariate logistic regression test and reporting odds ratio (OR) with ۹۵% confidence interval (CI) and multilevel, random intercept logistic regression models, the relationship between the evaluated factors and probability of death was assessed.Results: Data of ۳۱۵۸ patients with the mean age of ۳۱.۴۷±۱۶.۳۷ years (۷۳.۶۵% male) were evaluated. Apart from heart rate, the relationship of all the factors with probability of death was non-linear. The slope of mortality risk remained relatively constant with increase in heart rate, which means that with increase in heart rate, the probability of death also increased linearly (R۲=۰.۹۸; p<۰.۰۰۰۱). Probability of death in trauma patients is very low in respiratory rates less than ۱۴; however, in higher rates, the probability rises significantly (R۲=۰.۹۵; p<۰.۰۰۰۱). In addition, regarding arterial oxygen saturation level, probability of death is low in saturation levels over ۹۰% but increases significantly when it is under ۹۰% (R۲=۰.۹۴; p<۰.۰۰۰۱). Rise of the shock index to rates higher than ۱ also increases the probability of death significantly (R۲=۰.۹۳; p<۰.۰۰۰). When diastolic blood pressure is in the ۷۰-۹۰ mmHg range, probability of death is very low but it significantly rises in pressures less than this (R۲=۰.۹۷; p<۰.۰۰۰۱). A similar pattern exists regarding systolic blood pressure, which indicates a low probability of death when systolic blood pressure is over ۱۰۰ mmHg, yet the probability of death increases significantly when the pressure is lower than that (R۲=۰.۹۳; p<۰.۰۰۰۱).Conclusion: Findings of the present study showed that apart from heart rate, other evaluated factors had an s-shape correlation with mortality in trauma patients. In other words, with little change in any of these factors, mortality risk of trauma patients can rise significantly. Therefore, continuous monitoring of blood pressure, heart rate, respiratory rate, and arterial oxygen saturation level in emergency departments is of great importance.