Base deficit as an indicator of significant abdominal trauma at Kenyatta hospital

Abstract

Blunt abdominal trauma (BAT) is an important cause of morbidity and mortality among all age groups. Early recognition of significant BAT is of utmost importance in preventing adverse outcomes. Focused Abdominal Sonography for Trauma (FAST) is the screening method of choice while CT scan is currently the ideal method for haemo-dynamically stable patients. Base deficit (BD) has been proposed as an early available tool alongside FAST in the screening of patients suspected to have BAT and also to help guide the selective use of CT scan. However studies regarding the utility of BD as an indicator of BAT are few and there is no such study in our local set up. Objective: To determine the use of BD as an indicator of significant BAT Study Design: A Prospective observational Study. Setting: Kenyatta National Hospital, Nairobi Kenya Methodology: Ethical approval was sought and obtained from KNH\UON ERC. Data was collected from February 2015 to May 2015. Anon-randomized series of 134 patients (110 Males and 24 Females) with suspected BAT admitted into Accident & Emergency and who met the inclusion criteria were enrolled. History, physical examination findings and vital signs were noted. Arterial blood samples were analyzed for BD. FAST, CT scan, and or laparotomy were performed according to need to find intra-abdominal injury. Following clinical evaluation and investigations 81 patients were discharged from (A&E), 7 patents were discharged from the wards in 48 hrs after ruling out abdominal injury, 32 patients were managed conservatively for abdominal injury while 14 patients underwent explorative laparatomy. For those who were discharged from A&E or shortly from the wards without operation, follow up phone interviews were done after 7 days to find out their progress. 132 patients (108 males and 24 females) were analyzed. 2 patients were excluded from the study xii because one had a negative laparotomy while the other who had been discharged from (A&E) did not answer calls when he was contacted. Data analysis: Data was collected using a structured questionnaire and analyzed using SPSS 17.0 program. Receiver operating characteristic (ROC) curves were drawn and comparison of mean values of BD between different groups of patients (discharged from A&E, managed conservatively and operated) were performed using ANOVA. Results: BD values were significantly lower in patients who had abdominal injury compared to patients who had no abdominal injury (p=0.037). Similarly BD values were significantly lower in patients who had abdominal injury and underwent explorative laparotomy compared to those who had abdominal injury but were managed conservatively (p=0.029). For patients who had abdominal injury versus those who did not the cut-off value at which the greatest sum of sensitivity 82.98% and specificity 65.91 % was obtained for base deficit was -4.15. The PPV was 56.52% and the NPV was 87.88 %. For those who underwent explorative laparatomy versus those who did not the cut-off value was -6.85 with a sensitivity of 73.33% and specificity 58.06. The PPV was 45.83% and the NPV was 81.82 %. Conclusion The findings of our study show that BD is an early available tool that can be used to predict presence of AI as well as significant AI (injuries requiring exploratory laparotomy). At a cutoff of -4.15, the likelihood of abdominal injury is so high that an objective evaluation using imaging is warranted. On the other hand a normal BD, though an important indicator of absence of injury does not rule out presence of injury, however our findings show that a patient with significant intra-abdominal injuries requiring surgical intervention is unlikely to have a BD> -6.85 Meq/L