Elsevier

Injury

Volume 48, Issue 1, January 2017, Pages 51-57
Injury

End-tidal CO2 on admission is associated with hemorrhagic shock and predicts the need for massive transfusion as defined by the critical administration threshold: A pilot study

https://doi.org/10.1016/j.injury.2016.07.007Get rights and content

Abstract

Background

Critical administration threshold (≥3 units of packed red blood cells/h or CAT+) has been proposed as a new definition for massive transfusion (MT) that includes volume and rate of blood transfusion. CAT+ has been shown to eliminate survivor bias and be a better predictor of mortality than the traditional MT (>10 units/24 h). End-tidal CO2 (ET CO2) negatively correlates with lactate and is an early predictor of shock in trauma patients. We conducted a pilot study to test the hypothesis that low ET CO2 on admission predicts CAT+.

Methods

ET CO2 via capnography and serum lactate were prospectively collected on admission for 131 patients requiring trauma team activation. Demographic data were obtained from patient charts. Excluded were patients with isolated head injuries, traumatic arrests, or pre-hospital intubations. CAT± status was determined for each hour up to 6 h from admission as described; likewise, MT± status was determined up to 24 h from admission.

Results

After exclusion criteria, 67 patients were analyzed. Mean age was 41.2 (SD 18.5). Thirty-three patients had a blunt mechanism of injury (49%), median ISS was 9 (interquartile range 4–19), and there were 6 deaths (9%). ET CO2 and lactate were negatively correlated by Spearman rank-based correlation (rho = −0.41, p = 0.0006). Twenty-one (31%) and 8 (12%) patients were CAT+ and traditional MT+, respectively. There were a significantly greater proportion of patients with ISS > 15, ET CO2 <35, or who died found to be CAT+. A binomial logistic regression model adjusting for age, SBP <90, HR, and ISS >15 revealed ET CO2 < 35 to be independently predictive of CAT+ (OR 9.24, 95% CI 1.51-56.57, p = 0.016).

Conclusions

This pilot study demonstrated that low ET CO2 had strong association with standard indicators for shock and was predictive of patients meeting CAT+ criteria in the first 6 h after admission. Further study to verify these results and to elucidate CAT criteria’s association with mortality will require a larger sample size.

Section snippets

Background

Uncontrolled hemorrhage accounts for the majority of deaths in the first hour of trauma admissions and is responsible for almost 50% of deaths in the first 24 h [1], [2], [3]. A significant number of these patients, up to 40%, will present on admission with an acute coagulopathy of trauma shock [4], [5]. Early implementation of a massive transfusion (MT) protocol consisting of high ratios of plasma and platelets to packed red blood cells has been shown to improve survival in hemorrhaging trauma

Study patients

Following approval from the Institutional Review Board, we performed a prospective observational study where data were collected on patients presenting to our urban Level I trauma center between November 2012 and May 2015. Inclusion criteria included patients  18 years of age requiring the highest level of trauma team activation, and who had capnography and venous lactate measured. Exclusion criteria included patients with missing ET CO2 data; patients already intubated on arrival to trauma bay;

Results

Of 131 patients enrolled during the study period, 67 patients remained eligible for analysis following exclusion criteria (Fig. 1). Table 1 shows baseline demographics. The mean age of the study group was 41.2 years, where the majority (76%) of the patients were male. Blunt mechanism of injury comprised about half (49%) of the study group. The median ISS was nine and there were six (9%) patient deaths overall. Two patients died within 24 h of admission. More than half of the patients (60%)

Discussion

Expeditious activation of MT consisting of high ratios of plasma and platelets to PRBC’s improves survival in the hemorrhaging trauma patient [6], [7]. Therefore, early identification of those patients in the trauma bay who will need MT remains a top priority. For those patients who present with obvious signs of hemorrhagic shock, e.g. hypotension, identifying their need for MT is somewhat straightforward. On the other hand, given that trauma patients can present with normal vital signs yet

Conclusion

Our results demonstrate a significant and intriguing association between ET CO2 < 35 mmHg and established markers for shock that include SBP, SI and venous lactate for patients in the trauma bay. ET CO2 was found to be independently associated with CAT+ status when adjusting for age, ISS > 15, HR and SBP, however, the confidence intervals were large due to the small sample size. Given the small sample size of this study, although compelling, these results are preliminary and this should be

Authorship statement

MS—study design, data acquisition, analysis, interpretation of data, manuscript preparation.

SK—data acquisition, analysis, interpretation of data, manuscript preparation.

AL—analysis, interpretation of data, manuscript preparation.

ZA—data acquisition, analysis.

SY—data acquisition, analysis.

EC—intepretation of data, manuscript preparation.

SR—intepretation of data, manuscript preparation.

MJ—intepretation of data, manuscript preparation.

CV—data acquisition, interpretation of data.

ST—intepretation

Conflicts of interest

All authors declare that there are no conflicts of interest with regards to this study. The work was not funded by any outside institution.

Acknowledgement

The authors would like to thank Nicholas D. Caputo MD, our colleague and neighbor in the Bronx, for help in inspiring the use of capnograpy in the Jacobi Medical Center Emergency Department trauma bay.

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