Association of C - Reactive Protein and Body Mass Index with Duration of Mechanical Ventilation in Critically Ill Trauma Patients

Background and The aim of this study was to determine the incidence and presence of a relationship between predictors of body mass index (BMI) or C-reactive protein (CRP) and duration of mechanical ventilation, in trauma patients who were admitted to the intensive care unite (ICU). Furthermore, we compared their prognostic significance, with known indicators such as, the Sequential Organ Failure Assessment (SOFA) score. This prospective observational study was preformed on 72 admitted critically ill trauma patients in a general ICU setting, in Alzahra Medical Center of Isfahan University. Patients were categorized by duration of mechanical ventilation to the group A (≤ 7 days) and group B (> 7 days). The severity of illness was assessed by the Revised Trauma Score (RTS) calculated on the first admission to the ICU unit. The biological status of the patients was assessed by the serial measurement of CRP on admission to ICU (T1), at 48, 72 hours subsequently, and on the beginning day (T2) or discontinuation (T3) from mechanical ventilation. Data on BMI, serum albumin, and the SOFA score, were also collected on T2 and T3. There was no significant difference between two groups in demographic characteristic or RTS.On T3, the SOFA score, BMI, albumin, and CRP were significantly higher within group B patients, as compared with group A (P < 0.01). The incidence of low BMI (≤ 20 kg/m²) or high CRP (> 10 mg/L) on T2 was 72.2% (52/72) and 81.9% (59/72) respectively. The incidences of low BMI or high CRP in group B patients were significantly higher on T2 or T3, as compared with group A (P < 0.05). CRP or BMI on T3 had high specificity for predicting more than seven days of MV. On T3, the SOFA score, serum albumin, CRP, and BMI provided significantly good discrimination (area under curve > 0.5) in descending order. Mean serum CRP level within 72 hours after admission to the ICU or on T3 was significantly more in group B patients, as compared with group A (P < 0.01). The most significant predictor more than seven days of mechanical ventilation was CRP followed by BMI on T3. Both the BMI and CRP comparables with the SOFA score can be used in estimating the risk of prolonged mechanical ventilation. It is also concluded that maintaining the level of BMI or CRP in normal range, could shorten the duration of mechanical ventilation.