Utility of admission physiology in the surgical triage of isolated ballistic battlefield torso trauma

Use of Shock Index to Identify Mild Hemorrhage: An Observational Study in Military Blood Donors

Introduction:

Hemorrhage is the leading cause of preventable death in combat, although early recognition of hemorrhage is still challenging on the battlefield.

Hypothesis/Problem:

The objective of this study was to describe the shock index (SI) in a healthy military population, and to measure its variation during a controlled blood loss, simulated by blood donation.

Methods:

A prospective observational study that enrolled military subjects, volunteers for blood donation, was conducted. Demographic and clinical information, concerning both the patient and the blood collection, were recorded. Baseline vital signs were measured, before and after donation, in a 45° supine position. Statistical analysis was performed after calculation of SI.

Results:

A total of 483 participants were included in the study. The mean blood donation volume was 473mL (SD = 44mL). The median pre- and post-blood donation SI were significantly different: 0.54 (IQR = 0.48-0.63) and 0.57 (IQR = 0.49-0.66), respectively (P = .002). Changes in pre-/post-donation blood pressure (BP) and heart rate (HR) also reached statistical difference but represented a clinically poor relevance. The multivariate analysis showed no significant associations between SI variations and age, sex, body mass index (BMI), sport activities, blood donation volume, and enteral volume replacement (EVR).

Conclusion:

In this model of mild hemorrhage, SI exhibited significant variations but failed to reach clinical relevance. Further studies are needed to prove the benefit of SI calculation as a possible parameter for early recognition of hemorrhage in combat casualties at the point of injury.

Pasquier P, Duron S, Pouget T, Carbonnel AC, Boutonnet M, Malgras B, Barbier O, de Saint Maurice G, Sailliol A, Ausset S, Martinaud C. Use of shock index to identify mild hemorrhage: an observational study in military blood donors. Prehosp Disaster Med. 2019;34(3):303–307.

Vital sign patterns before shock-related cardiopulmonary arrest

OBJECTIVE

Traditional vital sign thresholds reflect an increased risk of mortality, which may occur hours, days, or weeks following illness/injury, limiting immediate clinical significance to guide rescue therapy to avoid arrest. Our objective is to explore vital sign patterns prior to arrest due to shock.

DESIGN

This retrospective observational analysis utilized physiological data from adult helicopter patients suffering provider-witnessed arrest. Pre-arrest values for systolic blood pressure (SBP), mean arterial pressure (MAP), heart rate (HR), shock index, and end-tidal carbon dioxide (EtCO2) were modeled against time using polynomial linear regression. The "terminal inflection point" beyond which arrest was imminent was identified where slope equals 1.0 (shock index) or -1.0 (SBP, MAP, HR, EtCO2) and was then compared to initial values.

SETTING

Air ambulance services.

PATIENTS

70 helicopter patients over age fourteen suffering cardiac arrest.

RESULTS

SBP and MAP demonstrated a gentle decline followed by acceleration beyond the inflection point (SBP 80.7 mmHg, MAP 61.9 mmHg). HR demonstrated an increase followed by a terminal drop, but inflection point values fell within normal range. Shock index increased gradually from a mean of 0.9 to the inflection point of 1.1. Initial EtCO2 values declined gradually from normal (34.4 mmHg) to the inflection point (24.7 mmHg), then dropped precipitously into arrest. All inflection points occurred 2-5 min prior to arrest.

CONCLUSIONS

Vital sign patterns were defined for SBP, MAP, HR, shock index, and EtCO2 with clear inflection points identified 2-5 min prior to arrest. These patterns may help guide therapy to reverse deterioration and prevent arrest.

Systolic Blood Pressure Threshold for HEMS-Witnessed Arrests

OBJECTIVE

Defining vital sign thresholds has focused on mortality, which may be delayed for hours, days, or weeks after injury. This limits the immediate clinical significance in guiding therapy to avoid arrest. The aim of this study was to identify a systolic blood pressure (SBP) threshold indicating imminent cardiopulmonary arrest.

METHODS

This was a retrospective, observational study analyzing physiological data from air medical patients suffering witnessed arrest. We limited the analysis to a subgroup of adult (> 14 years) patients with hypoperfusion-related arrest. Prearrest SBP values were plotted over time, with arrest defined as "time zero." Multiple linear regression was used to define a best fit curve to identify an inflection point beyond which arrest was imminent.

RESULTS

A total of 53 eligible patients were identified; 33 (62%) were trauma victims. A fifth-degree equation showed appropriate goodness of fit (r = -.66, P < .0001). An inflection point was identified at an SBP of 78 mm Hg, with arrest occurring approximately 3 minutes later.

CONCLUSION

An inflection point below SBP 80 mm Hg was identified, suggesting a predictable physiological pattern for perfusion-related deterioration. This may help guide therapy to reverse deterioration and prevent arrest.

Improvements in the hemodynamic stability of combat casualties during en route care

Three Forward Aeromedical Evacuation platforms operate in Southern Afghanistan: UK Medical Emergency Response Team (MERT), US Air Force Expeditionary Rescue Squadron (PEDRO), and US Army Medical Evacuation Squadrons (DUSTOFF), each with a different clinical capability. Recent evidence suggests that retrieval by a platform with a greater clinical capability (MERT) is associated with improved mortality in critical patients when compared with platforms with less clinical capability (PEDRO and DUSTOFF). It is unclear whether this is due to en route resuscitation or the dispatch procedure. The aim of this study was to compare prehospital Shock Index (SI = heart rate / systolic blood pressure) with admission values as a measure of resuscitation, across these platforms. Patients were identified from the Department of Defense Trauma Registry, who were evacuated between June 2009 and June 2011 in Southern Afghanistan. Data on platform type, physiology, and injury severity was extracted. Overall, 865 patients were identified: 478 MERT, 291 PEDRO, and 96 DUSTOFF patients and groups were compared across three injury severity scoring (ISS) bins: 1 to 9, 10 to 25, and 26 or greater. An improvement in the admission SI was observed across all platforms in the lowest ISS bin. Within the middle bin, both the MERT and PEDRO groups saw improved SI on admission, but not the DUSTOFF group. This trend was continued only in the MERT group for the highest ISS bin (1.39 ± 0.62 vs. 1.09 ± 0.42; P = 0.001), whereas a deterioration was identified in the PEDRO group (0.88 ± 0.37 vs. 1.02 ± 0.43; P = 0.440). The use of a Forward Aeromedical Evacuation platform with a greater clinical capability is associated with an improved hemodynamic status in critical casualties. The ideal prehospital triage should endeavor to match patient need with clinical capability.

Do patients with penetrating abdominal stab wounds require laparotomy?

BACKGROUND

The optimal management of hemodynamically stable asymptomatic patients with anterior abdominal stab wounds (AASWs) remains controversial. The goal is to identify and treat injuries in a safe cost-effective manner. Common evaluation strategies are local wound exploration (LWE), diagnostic peritoneal lavage (DPL), serial clinical assessment (SCAs) and computed tomography (CT) imaging. Making a decision about the right time to operate on a patient with a penetrating abdominal stab wound, especially those who have visceral evisceration, is a continuing challenge.

OBJECTIVES

Until the year 2010, our strategy was emergency laparotomy in patients with penetrating anterior fascia and those with visceral evisceration. This survey was conducted towards evaluating the results of emergency laparotomy. So, better management can be done in patients with penetrating abdominal stab wounds.

PATIENTS AND METHODS

This retrospective cross-sectional study was performed on patients with abdominal penetrating trauma who referred to Al- Zahra hospital in Isfahan, Iran from October 2000 to October 2010. It should be noted that patients with abdominal blunt trauma, patients under 14 years old, those with lateral abdomen penetrating trauma and patients who had unstable hemodynamic status were excluded from the study. Medical records of patients were reviewed and demographic and clinical data were collected for all patients including: age, sex, mechanism of trauma and the results of LWE and laparotomy. Data were analyzed with PASW v.20 software. All data were expressed as mean ± SD. The distribution of nominal variables was compared using the Chi-squared test. Also, diagnostic index for LWE were calculated. A two-sided P value less than 0.05 was considered to be statistically significant.

RESULTS

During the 10 year period of the study, 1100 consecutive patients with stab wounds were admitted to Al-Zahra hospital Isfahan, Iran. In total, about 150 cases had penetrating traumas in the anterior abdomen area. Sixty-three (42%) patients were operated immediately due to shock, visceral evisceration or aspiration of blood via a nasogastric tube on admission. Organ injury was seen in 78% of patients with visceral evisceration. Among these 87 cases, 29 patients' (33.3%) anterior fascia was not penetrated in LWE. So, they were observed for several hours and discharged from the hospital without surgery. While for the remaining 58 patients (66.6%), whose LWE detected penetration of anterior abdominal fascia, laparotomy was performed which showed visceral injuries in 11 (18%) cases.

CONCLUSIONS

All in all, 82 percent of laparotomies in patients with penetrated anterior abdominal fascia without visceral evisceration, who had no signs of peritoneal irritation, were negative. So, we recommended further evaluation in these patients. However, visceral evisceration is an indication for exploratory laparotomy, since in our study; the majority of patients had organ damages.

The value of the difference between ED and prehospital vital signs in predicting outcome in trauma

INTRODUCTION

Traditional vital signs are seen as an important part of trauma assessment, despite their poor predictive value in this regard.

OBJECTIVE

This study evaluated whether the difference between systolic blood pressure (SBP), heart rate (HR), respiratory rate (RR) and shock index (SI) taken in the emergency department (ED) and prehospital can predict 48 h mortality postadmission following trauma.

METHODS

Retrospective cohort was obtained from the Trauma Audit and Research Network. Subjects were excluded if head or spinal injuries, prehospital intubation or CPR were present. Main outcome was 48 h mortality. The difference (delta, Δ) between ED and prehospital values were used as study variables (ie, ΔSI=SI-ED minus SI-prehospital). Accuracy was assessed using area under receiver operator characteristic curve (AUROC). AUROC coordinates were used to identify 95% specificity cut points and described further using sensitivity and likelihood ratios (LRs).

RESULTS

Significant AUROC statistics were revealed for ΔSBP (0.57) and ΔRR (0.56) for the full sample, ΔSBP (0.62) and ΔSI (0.65) for moderate, and ΔRR (0.6) for severe injury. Best LRs were 3.4 and 2.4 for ΔRR and ΔSI, respectively, but sensitivities were low (<=26%). Cut point values for ΔSBP, ΔRR and ΔSI were 37 mm Hg, 8 breaths/min and 0.2, respectively.

DISCUSSION

ΔSBP and ΔRR performed best overall, but ΔSI performed best in the moderate injury group, suggesting earlier identification with ΔSI. Use of Δ values result in good rule-in of 48 h mortality and may supplement trauma treatment decisions.