The impact of prehospital whole blood on hemorrhaging trauma patients: A multi-center retrospective study.

BACKGROUND: Whole blood (WB) use has become increasingly common in trauma centers across the United States for both in-hospital and prehospital resuscitation. We hypothesize that prehospital WB (pWB) use in trauma patients with suspected hemorrhage will result in improved hemodynamic status and reduced in-hospital blood product requirements. METHODS: The institutional trauma registries of two academic level I trauma centers were queried for all patients from 2015-2019 who underwent transfusion upon arrival to the trauma bay. Patients who were dead on arrival or had isolated head injuries were excluded. Demographics, injury and shock characteristics, transfusion requirements, including massive transfusion protocol (MTP) (>10 U in 24 hours) and rapid transfusion (CAT3+) and outcomes were compared between pWB and non-pWB patients. Significantly different demographic, injury characteristics and pWB were included in univariate followed by stepwise logistic regression analysis to determine the relationship with shock index (SI). Our primary objective was to determine the relationship between pWB and improved hemodynamics or reduction in blood product utilization. RESULTS: A total of 171 pWB and 1391 non-pWB patients met inclusion criteria. Prehospital WB patients had a lower median Injury Severity Score (17 vs. 21, p < 0.001) but higher prehospital SI showing greater physiologic disarray. Prehospital WB was associated with improvement in SI (-0.04 vs. 0.05, p = 0.002). Mortality and (LOS) were similar. Prehospital WB patients received fewer packed red blood cells, fresh frozen plasma, and platelets units across their LOS but total units and volumes were similar. Prehospital WB patients had fewer MTPs (22.6% vs. 32.4%, p = 0.01) despite a similar requirement of CAT3+ transfusion upon arrival. CONCLUSION: Prehospital WB administration is associated with a greater improvement in SI and a reduction in MTP. This study is limited by its lack of power to detect a mortality difference. Prospective randomized controlled trials will be required to determine the true impact of pWB on trauma patients. LEVEL OF EVIDENCE: Prognostic and Epidemiological; Level IV.

Prehospital shock index and systolic blood pressure are highly specific for pediatric massive transfusion.

BACKGROUND: While massive transfusion protocols (MTPs) are associated with decreased mortality in adult trauma patients, there is limited research on the impact of MTP on pediatric trauma patients. The purpose of this study was to compare pediatric trauma patients requiring massive transfusion with all other pediatric trauma patients to identify triggers for MTP activation in injured children. METHODS: Using our level I trauma center's registry, we retrospectively identified all pediatric trauma patients from January 2015 to January 2018. Massive transfusion (MT) was defined as infusion of 40 mL/kg of blood products in the first 24 hours of admission. Patients missing prehospital vital sign data were excluded from the study. We retrospectively collected data including demographics, blood utilization, variable outcome data, prehospital vital signs, prehospital transport times, and Injury Severity Scores. Statistical significance was determined using Mann-Whitney U test and χ2 test. p Values of less than 0.05 were considered significant. RESULTS: Thirty-nine (1.9%) of the 2,035 pediatric patients met the criteria for MT. All-cause mortality in MT patients was 49% (19 of 39 patients) versus 0.01% (20 of 1996 patients) in non-MT patients. The two groups significantly differed in Injury Severity Score, prehospital vital signs, and outcome data.Both systolic blood pressure (SBP) of <100 mm Hg and shock index (SI) of >1.4 were found to be highly specific for MT with specificities of 86% and 92%, respectively. The combination of SBP of <100 mm Hg and SI of >1.4 had a specificity of 94%. The positive and negative predictive values of SBP of <100 mm Hg and SI of >1.4 in predicting MT were 18% and 98%, respectively. Based on positive likelihood ratios, patients with both SBP of <100 mm Hg and SI of >1.4 were 7.2 times more likely to require MT than patients who did not meet both of these vital sign criteria. CONCLUSION: Pediatric trauma patients requiring early blood transfusion present with lower blood pressures and higher heart rates, as well as higher SIs and lower pulse pressures. We found that SI and SBP are highly specific tools with promising likelihood ratios that could be used to identify patients requiring early transfusion. LEVEL OF EVIDENCE: Therapeutic/care management, level V.

The gut microbiome distinguishes mortality in trauma patients upon admission to the emergency department.

BACKGROUND: Traumatic injury can lead to a compromised intestinal epithelial barrier, decreased gut perfusion, and inflammation. While recent studies indicate that the gut microbiome (GM) is altered early following traumatic injury, the impact of GM changes on clinical outcomes remains unknown. Our objective of this follow-up study was to determine if the GM is associated with clinical outcomes in critically injured patients. METHODS: We conducted a prospective, observational study in adult patients (N = 67) sustaining severe injury admitted to a level I trauma center. Fecal specimens were collected on admission to the emergency department, and microbial DNA from all samples was analyzed using the Quantitative Insights Into Microbial Ecology pipeline and compared against the Greengenes database. α-Diversity and ß-diversity were estimated using the observed species metrics and analyzed with t tests and permutational analysis of variance for overall significance, with post hoc pairwise analyses. RESULTS: Our patient population consisted of 63% males with a mean age of 44 years. Seventy-eight percent of the patients suffered blunt trauma with 22% undergoing penetrating injuries. The mean body mass index was 26.9 kg/m. Significant differences in admission ß-diversity were noted by hospital length of stay, intensive care unit hospital length of stay, number of days on the ventilator, infections, and acute respiratory distress syndrome (p < 0.05). ß-Diversity on admission differed in patients who died compared with patients who lived (mean time to death, 8 days). There were also significantly less operational taxonomic units in samples from patients who died versus those who survived. A number of species were enriched in the GM of injured patients who died, which included some traditionally probiotic species such as Akkermansia muciniphilia, Oxalobacter formigenes, and Eubacterium biforme (p < 0.05). CONCLUSION: Gut microbiome diversity on admission in severely injured patients is predictive of a variety of clinically important outcomes. While our study does not address causality, the GM of trauma patients may provide valuable diagnostic and therapeutic targets for the care of injured patients. LEVEL OF EVIDENCE: Prognostic and epidemiological, level III.

Shock index and pulse pressure as triggers for massive transfusion.

BACKGROUND: Hemorrhage is the most common cause of preventable death in trauma patients. These mortalities might be prevented with prehospital transfusion. We sought to characterize injured patients requiring massive transfusion to determine the potential impact of a prehospital whole blood transfusion program. The primary goal of this analysis was to determine a method to identify patients at risk of massive transfusion in the prehospital environment. Many of the existing predictive models require laboratory values and/or sonographic evaluation of the patient after arrival at the hospital. Development of an algorithm to predict massive transfusion protocol (MTP) activation could lead to an easy-to-use tool for prehospital personnel to determine when a patient needs blood transfusion. METHODS: Using our Level I trauma center's registry, we retrospectively identified all adult trauma patients from January 2015 to August 2017 requiring activation of the MTP. Patients who were younger than 18 years, older than 89 years, prisoners, pregnant women, and/or with nontraumatic hemorrhage were excluded from the study. We retrospectively collected data including demographics, blood utilization, variable outcome data (survival, length of stay, intensive care unit days, ventilator days), prehospital vital signs, prehospital transport times, and Injury Severity Score. The independent-samples t test and χ test were used to compare the group who died to the group who survived. p < 0.05 was considered significant. Based on age and mechanism of injury, relative risk of death was calculated. Graphs were generated using Microsoft Excel software to plot patient variables. RESULTS: Our study population of 102 MTP patients had an average age of 42 years and average Injury Severity Score of 29, consisted of 80% males (82/102), and was 66% blunt trauma (67/102). The all-cause mortality was 67% (68/102). The positive predictive value of death for patients with pulse pressure of less than 45 and shock index of greater than 1 was 0.78 for all patients, but was 0.79 and 0.92 for blunt injury and elderly patients, respectively. CONCLUSIONS: Our data demonstrate a high mortality rate in trauma patients who require MTP despite short transport times, indicating the need for early intervention in the prehospital environment. Given our understanding that the most severely injured patients in hemorrhagic shock require blood resuscitation, this study demonstrates that this subset of trauma patients requiring massive transfusion can be identified in the prehospital setting. We recommend using Emergency Medical Services pulse pressure in combination with shock index to serve as a trigger for initiation of prehospital whole blood transfusion. LEVEL OF EVIDENCE: Therapeutic/care management, level V.

A prospective study in severely injured patients reveals an altered gut microbiome is associated with transfusion volume.

BACKGROUND: Traumatic injury can lead to a compromised intestinal epithelial barrier and inflammation. While alterations in the gut microbiome of critically injured patients may influence clinical outcomes, the impact of trauma on gut microbial composition is unknown. Our objective was to determine if the gut microbiome is altered in severely injured patients and begin to characterize changes in the gut microbiome due to time and therapeutic intervention. METHODS: We conducted a prospective, observational study in adult patients (n = 72) sustaining severe injury admitted to a Level I Trauma Center. Healthy volunteers (n = 13) were also examined. Fecal specimens were collected on admission to the emergency department and at 3, 7, 10, and 13 days (±2 days) following injury. Microbial DNA was isolated for 16s rRNA sequencing, and α and ß diversities were estimated, according to taxonomic classification against the Greengenes database. RESULTS: The gut microbiome of trauma patients was altered on admission (i.e., within 30 minutes following injury) compared to healthy volunteers. Patients with an unchanged gut microbiome on admission were transfused more RBCs than those with an altered gut microbiome (p < 0.001). Although the gut microbiome started to return to a ß-diversity profile similar to that of healthy volunteers over time, it remained different from healthy controls. Alternatively, α diversity initially increased postinjury, but subsequently decreased during the hospitalization. Injured patients on admission had a decreased abundance of traditionally beneficial microbial phyla (e.g., Firmicutes) with a concomitant decrease in opportunistic phyla (e.g., Proteobacteria) compared to healthy controls (p < 0.05). Large amounts of blood products and RBCs were both associated with higher α diversity (p < 0.001) and a ß diversity clustering closer to healthy controls. CONCLUSION: The human gut microbiome changes early after trauma and may be aided by early massive transfusion. Ultimately, the gut microbiome of trauma patients may provide valuable diagnostic and therapeutic insight for the improvement of outcomes postinjury. LEVEL OF EVIDENCE: Prognostic and Epidemiological, level III.

Impact of low-dose vasopressin on trauma outcome: prospective randomized study.

BACKGROUND: We previously found that regardless of the animal injury model used resuscitation strategies that minimize fluid administration requirements lead to better outcomes. We hypothesized that a resuscitation regimen that limited the total volume of fluid administered would reduce morbidity and mortality rates in critically ill trauma patients. METHODS: We performed a double-blind randomized trial to assess the safety and efficacy of adding vasopressin to resuscitative fluid. Subjects were hypotensive adults who had sustained acute traumatic injury. Subjects were given fluid alone (control group) or fluid plus vasopressin (experimental group), first as a bolus (4 IU) and then as an intravenous infusion of 200 ml/h (vasopressin 2.4 IU/h) for 5 h. RESULTS: We randomly assigned 78 patients to the experimental group (n=38) or the control group (n=40). The groups were similar in age, sex, preexisting medical illnesses, and mechanism and severity of injury. Serum vasopressin concentrations were higher in the experimental group than in the control group at admission, after infusion of vasopressin (p=0.01), and 12 h later. The experimental group required a significantly lower total volume of resuscitation fluid over 5 days than did the control group (p=0.04). The mortality rate at 5 days was 13% in the experimental group and 25% in the control group (p=0.19). The rates of adverse events, organ dysfunction, and 30-day mortality were similar. CONCLUSIONS: This is the first trial to investigate the impact of vasopressin administration in trauma patients. Infusion of low-dose vasopressin maintained elevated serum vasopressin levels and decreased fluid requirements after injury.

Computed tomography grading systems poorly predict the need for intervention after spleen and liver injuries.

Computed tomography (CT) grading systems are often used clinically to forecast the need for interventions after abdominal trauma with solid organ injuries. We compared spleen and liver CT grading methods to determine their utility in predicting the need for operative intervention or angiographic embolization. Abdominal CT scans of 300 patients with spleen injuries, liver injuries, or both were evaluated by five trauma faculty members blinded to clinical outcomes. Studies were graded by American Association for the Surgery of Trauma criteria, a novel splenic injury CT grading system, and a novel liver injury grading system. The sensitivity and specificity of each methodology in predicting the need for intervention were calculated. The kappa statistic was used to determine interrater variability. Twenty-one per cent (39/189) of patients with splenic injuries visible on CT scans required interventions, whereas 14 per cent (21/154) of patients with liver injuries visible on CT required interventions. The overall sensitivity of all grading systems in predicting the need for surgery or angioembolization of the spleen or liver was poor; the specificity seemed to be fairly good. When evaluators were compared, the strength of agreement for the various scoring systems was only moderate. Anatomic CT grading systems are ineffective screening tools for excluding the need for operation or embolization after splenic or hepatic trauma. Although insensitive, CT is a good predictor (highly specific) of the need for intervention if certain definitive abnormalities are identified. Considerable inconsistency exists in interpretation of abdominal CT scans after trauma, even among experienced clinicians.

Surgical critical care and private practice surgeons: a different world out there!

BACKGROUND: Few graduating residents seek surgical critical care (SCC) fellowships; fewer than half of positions fill. We hypothesized substantial differences exist in practice patterns and attitudes between SCC surgeons in academic practice (ACs) and in private practice (PVTs). STUDY DESIGN: A survey instrument was sent to 1,544 board-certified SCC intensivists in North America. RESULTS: Of those invited, 489 responded (32% response rate). Respondents were mostly men (88%) and Caucasian (86%), with a mean age of 48 years; 60% were ACs, 28% were PVTs, and 12% reported "other;" 94% currently practiced SCC. PVTs (50%) were more likely than ACs (18%) to provide SCC for only their own patients, less likely (24% versus 74%) to function as an "ICU attending," and less likely to work with residents (36% versus 91%) and fellows (4% versus 60%; all p < 0.001). PVTs (48%) spent more time performing elective operations than ACs (27%; p < 0.001). They were more likely than ACs to relinquish management of SCC patients to medical consultants: infectious disease (34% versus 12%), cardiology (31% versus 12%), and pulmonary (23% versus 3%; all p < 0.001). Conflicts with medical specialists were a bigger problem for PVTs (43%) than for ACs (17%; p < 0.001). CONCLUSIONS: Private practice surgical intensivists are more likely than academic intensivists to provide critical care for only their own patients and to use consultants to avoid conflicts.