Stacy Shackelford

Necrotizing soft tissue infections: delayed surgical treatment is associated with increased number of surgical debridements and morbidity.

BACKGROUND Early surgical treatment is crucial in the management of necrotizing soft tissue infections (NSTI), a severe, potentially life threatening, rapidly progressive infection. The purpose of this study was to determine the influence of surgical procedure timing on the number of surgical debridements required. METHODS A retrospective study including 47 patients with the diagnosis of NSTI admitted to a large academic hospital from December 2004 to December 2010 was conducted. Demographics, basic laboratories on admission, medical comorbidities, site of infection, and intraoperative culture results were compared between patients with early (≤12 hour) and late (>12 hour) surgical treatment. The x-y plot for the study population and linear regression analyses were used to define the time cut point. Outcomes included the total number of debridements, mortality, hospital length of stay, and complications. Adjustment for confounding factors was done with binary regression logistic model for categorical outcomes and analysis of covariants for continuous outcomes. RESULTS Overall mortality was 17.0%. The average number of surgical debridements in patients with delay surgical treatment >12 hours from the time of emergency department admission was significantly higher than those who had an operation within 12 hours after admission (7.4 ± 2.5 vs. 2.3 ± 1.2; p < 0.001). Delayed surgical debridement was associated with significantly higher mortality, higher incidence of septic shock and renal failure, and more surgical debridements than patients with early surgical debridements. After adjusting for possible confounding factors, the average number of surgical debridements and the presence of septic shock and acute renal failure were still significantly higher in patients in whom surgery was delayed >12 hours. CONCLUSION In patients with NSTI, a delay of surgical treatment of >12 hours is associated with an increased number of surgical debridements and higher incidence of septic shock and acute renal failure.

Prehospital Blood Product Transfusion by U.S. Army MEDEVAC During Combat Operations in Afghanistan: A Process Improvement Initiative

U.S. Army flight medics performed a process improvement initiative of 15 blood product transfusions on select Category A (Urgent) helicopter evacuation casualties meeting approved clinical indications for transfusion. These transfusions were initiated from point of injury locations aboard MEDEVAC aircraft originating from one of two locations in southern Afghanistan. All flight medics executing the transfusions were qualified through a standardized and approved program of instruction, which included day and night skills validation, and a 90% or higher written examination score. There was no adverse reaction or out-of-standard blood product temperature despite hazardous conditions and elevated cabin temperatures. All casualties within a 10-minute flight time who met clinical indications were transfused. Utilization of a standard operating procedure with strict handling and administration parameters, a rigorous training and qualification program, an elaborate cold chain system, and redundant documentation of blood product units ensured that flight medic initiated transfusions were safe and effective. Research study is needed to refine the indications for prehospital blood transfusion and to determine the effect on outcomes in severely injured trauma patients.

Automated Prediction of Early Blood Transfusion and Mortality in Trauma Patients

BACKGROUND Prediction of blood transfusion needs and mortality for trauma patients in near real time is an unrealized goal. We hypothesized that analysis of pulse oximeter signals could predict blood transfusion and mortality as accurately as conventional vital signs (VSs). METHODS Continuous VS data were recorded for direct admission trauma patients with abnormal prehospital shock index (SI = heart rate [HR] / systolic blood pressure) greater than 0.62. Predictions of transfusion during the first 24 hours and in-hospital mortality using logistical regression models were compared with DeLong’s method for areas under receiver operating characteristic curves (AUROCs) to determine the optimal combinations of prehospital SI and HR, continuous photoplethysmographic (PPG), oxygen saturation (SpO2), and HR-related features. RESULTS We enrolled 556 patients; 37 received blood within 24 hours; 7 received more than 4 U of red blood cells in less than 4 hours or “massive transfusion” (MT); and 9 died. The first 15 minutes of VS signals, including prehospital HR plus continuous PPG, and SpO2 HR signal analysis best predicted transfusion at 1 hour to 3 hours, MT, and mortality (AUROC, 0.83; p < 0.03) and no differently (p = 0.32) from a model including blood pressure. Predictions of transfusion based on the first 15 minutes of data were no different using 30 minutes to 60 minutes of data collection. SI plus PPG and SpO2 signal analysis (AUROC, 0.82) predicted 1-hour to 3-hour transfusion, MT, and mortality no differently from pulse oximeter signals alone. CONCLUSION Pulse oximeter features collected in the first 15 minutes of our trauma patient resuscitation cohort, without user input, predicted early MT and mortality in the critical first hours of care better than the currently used VS such as combinations of HR and systolic blood pressure or prehospital SI alone. LEVEL OF EVIDENCE Therapeutic/prognostic study, level II.

Early identification of uncontrolled hemorrhage after trauma: Current status and future direction

D uring the last decade, advanced trauma care surgical and transfusion teams have achieved remarkable gains in the rapid identification and effective response to potentially lethal hemorrhage, and these improvements are now demonstrable in improved survival and decreased blood product use. However, uncontrolled hemorrhage remains the most common cause of potentially preventable death after both civilian and military trauma, and of those who survive to reach advanced care, half will die in the first 2 hours after admission. Changes in the types and proportions of blood product requirements are also driving changes in blood banking procedures for product testing, release, and delivery. It is likely that the next evolution in improved survival from traumatic injury will occur in the realm of en route care through the introduction of advanced capabilities at the point of injury and during aeromedical transport. However, the ability to move a rapid, accurate, and practical diagnostic capability into the field medical response and the aviation transport process remains an unrealized goal in modern trauma care. In this review, using large-scale transfusion requirements (so-called massive transfusion [MT]) as a surrogate marker for uncontrolled hemorrhage, we will examine the history and current status of efforts to rapidly identify bleeding casualties and predict the need for immediate hemorrhage control procedures and transfusion.

Intraosseous infusion rates under high pressure: a cadaveric comparison of anatomic sites.

BACKGROUND When traditional vascular access methods fail, emergency access through the intraosseous (IO) route can be lifesaving. Fluids, medications, and blood components have all been delivered through these devices. We sought to compare the performance of IO devices placed in the sternum, humeral head, and proximal tibia using a fresh human cadaver model. METHODS Commercially available IO infusion devices were placed into fresh human cadavers: sternum (FAST-1), humeral head (EZ-IO), and proximal tibia (EZ-IO). Sequentially, the volume of 0.9% saline infused into each site under 300 mm Hg pressure over 5 minutes was measured. Rates of successful initial IO device placement and subjective observations related to the devices were also recorded. RESULTS For 16 cadavers over a 5-minute bolus infusion, the total volume of fluid infused at the three IO access sites was 469 (190) mL for the sternum, 286 (218) mL for the humerus, and 154 (94) mL for the tibia. Thus, the mean (SD) flow rate infused at each site was as follows: (1) sternum, 93.7 (37.9) mL/min; (2) humerus, 57.1 (43.5) mL/min; and (3) tibia, 30.7 (18.7) mL/min. The tibial site had the greatest number of insertion difficulties. CONCLUSION This is the first study comparing the rate of flow at the three most clinically used adult IO infusion sites in an adult human cadaver model. Our results showed that the sternal site for IO access provided the most consistent and highest flow rate compared with the humeral and tibial insertion sites. The average flow rate in the sternum was 1.6 times greater than in the humerus and 3.1 times greater than in the tibia.

Association of Prehospital Blood Product Transfusion During Medical Evacuation of Combat Casualties in Afghanistan With Acute and 30-Day Survival

Importance Prehospital blood product transfusion in trauma care remains controversial due to poor-quality evidence and cost. Sequential expansion of blood transfusion capability after 2012 to deployed military medical evacuation (MEDEVAC) units enabled a concurrent cohort study to focus on the timing as well as the location of the initial transfusion. Objective To examine the association of prehospital transfusion and time to initial transfusion with injury survival. Design, Setting, and Participants Retrospective cohort study of US military combat casualties in Afghanistan between April 1, 2012, and August 7, 2015. Eligible patients were rescued alive by MEDEVAC from point of injury with either (1) a traumatic limb amputation at or above the knee or elbow or (2) shock defined as a systolic blood pressure of less than 90 mm Hg or a heart rate greater than 120 beats per minute. Exposures Initiation of prehospital transfusion and time from MEDEVAC rescue to first transfusion, regardless of location (ie, prior to or during hospitalization). Transfusion recipients were compared with nonrecipients (unexposed) for whom transfusion was delayed or not given. Main Outcomes and Measures Mortality at 24 hours and 30 days after MEDEVAC rescue were coprimary outcomes. To balance injury severity, nonrecipients of prehospital transfusion were frequency matched to recipients by mechanism of injury, prehospital shock, severity of limb amputation, head injury, and torso hemorrhage. Cox regression was stratified by matched groups and also adjusted for age, injury year, transport team, tourniquet use, and time to MEDEVAC rescue. Results Of 502 patients (median age, 25 years [interquartile range, 22 to 29 years]; 98% male), 3 of 55 prehospital transfusion recipients (5%) and 85 of 447 nonrecipients (19%) died within 24 hours of MEDEVAC rescue (between-group difference, −14% [95% CI, −21% to −6%]; P = .01). By day 30, 6 recipients (11%) and 102 nonrecipients (23%) died (between-group difference, −12% [95% CI, −21% to −2%]; P = .04). For the 386 patients without missing covariate data among the 400 patients within the matched groups, the adjusted hazard ratio for mortality associated with prehospital transfusion was 0.26 (95% CI, 0.08 to 0.84, P = .02) over 24 hours (3 deaths among 54 recipients vs 67 deaths among 332 matched nonrecipients) and 0.39 (95% CI, 0.16 to 0.92, P = .03) over 30 days (6 vs 76 deaths, respectively). Time to initial transfusion, regardless of location (prehospital or during hospitalization), was associated with reduced 24-hour mortality only up to 15 minutes after MEDEVAC rescue (median, 36 minutes after injury; adjusted hazard ratio, 0.17 [95% CI, 0.04 to 0.73], P = .02; there were 2 deaths among 62 recipients vs 68 deaths among 324 delayed transfusion recipients or nonrecipients). Conclusions and Relevance Among medically evacuated US military combat causalities in Afghanistan, blood product transfusion prehospital or within minutes of injury was associated with greater 24-hour and 30-day survival than delayed transfusion or no transfusion. The findings support prehospital transfusion in this setting.

Comparison of Decision-Assist and Clinical Judgment of Experts for Prediction of Lifesaving Interventions.

ABSTRACT Early recognition of hemorrhage during the initial resuscitation of injured patients is associated with improved survival in both civilian and military casualties. We tested a transfusion and lifesaving intervention (LSI) prediction algorithm in comparison with clinical judgment of expert trauma care providers. We collected 15 min of pulse oximeter photopletysmograph waveforms and extracted features to predict LSIs. We compared this with clinical judgment of LSIs by individual categories of prehospital providers, nurses, and physicians and a combined judgment of all three providers using the Area Under Receiver Operating Curve (AUROC). We obtained clinical judgment of need for LSI from 405 expert clinicians in135 trauma patients. The pulse oximeter algorithm predicted transfusion within 6 h (AUROC, 0.92; P < 0.003) more accurately than either physicians or prehospital providers and as accurately as nurses (AUROC, 0.76; P = 0.07). For prediction of surgical procedures, the algorithm was as accurate as the three categories of clinicians. For prediction of fluid bolus, the diagnostic algorithm (AUROC, 0.9) was significantly more accurate than prehospital providers (AUROC, 0.62; P = 0.02) and nurses (AUROC, 0.57; P = 0.04) and as accurate as physicians (AUROC, 0.71; P = 0.06). Prediction of intubation by the algorithm (AUROC, 0.92) was as accurate as each of the three categories of clinicians. The algorithm was more accurate (P < 0.03) for blood and fluid prediction than the combined clinical judgment of all three providers but no different from the clinicians in the prediction of surgery (P = 0.7) or intubation (P = 0.8). Automated analysis of 15 min of pulse oximeter waveforms predicts the need for LSIs during initial trauma resuscitation as accurately as judgment of expert trauma clinicians. For prediction of emergency transfusion and fluid bolus, pulse oximetry features were more accurate than these experts. Such automated decision support could assist resuscitation decisions, trauma team, and operating room and blood bank preparations.

Prehospital Pain Medication Use by U.S. Forces in Afghanistan

We report the results of a process improvement initiative to examine the current use and safety of prehospital pain medications by U.S. Forces in Afghanistan. Prehospital pain medication data were prospectively collected on 309 casualties evacuated from point of injury (POI) to surgical hospitals from October 2012 to March 2013. Vital signs obtained from POI and flight medics and on arrival to surgical hospitals were compared using one-way analysis of variance test. 119 casualties (39%) received pain medication during POI care and 283 (92%) received pain medication during tactical evacuation (TACEVAC). Morphine and oral transmucosal fentanyl citrate were the most commonly used pain medications during POI care, whereas ketamine and fentanyl predominated during TACEVAC. Ketamine was associated with increase in systolic blood pressure compared to morphine (+7 ± 17 versus -3 ± 14 mm Hg, p = 0.04). There was no difference in vital signs on arrival to the hospital between casualties who received no pain medication, morphine, fentanyl, or ketamine during TACEVAC. In this convenience sample, fentanyl and ketamine were as safe as morphine for prehospital use within the dose ranges administered. Future efforts to improve battlefield pain control should focus on improved delivery of pain control at POI and the role of combination therapies.

The Epidemiology of Critical Care Air Transport Team Operations in Contemporary Warfare

Critical Care Air Transport Teams (CCATTs) have evolved as a vital component of the U.S. Air Forces aeromedical evacuation system. Previous epidemiological research in this area is limited. The objective of this commentary is to highlight the importance of obtaining robust epidemiological data regarding patients transported by CCATTs. A limited epidemiological analysis was performed to describe CCATT patients transported during Operation Enduring Freedom and the waning months of Operation Iraqi Freedom. CCATT transports for the calendar year 2011 were examined as recorded in the U.S. Transportation Command Regulating and Command and Control (C2) Evacuation System database. As many as 290 CCATT primary patient transport records were reviewed. Of these, 58.6% of patients had multiple injuries, 15.9% of patients had traumatic brain injury, 7% had acute coronary syndromes, and 24.8% of all transports were for nonbattle-related injuries. The most common International Classification of Disease, 9th Edition, Clinical Modification coded injury was bilateral lower extremity amputation (40%). Explosive blasts were the top mechanism of injury for patients requiring CCAT. The distribution of injuries and illnesses requiring CCAT appear to have changed compared to previous conventional conflicts. Understanding the epidemiology of casualties evacuated by CCATT during modern warfare is a prerequisite for the development of effective predeployment training to ensure optimal outcomes for critically ill and injured warriors.

Identification of dynamic prehospital changes with continuous vital signs acquisition.

OBJECTIVE In most trauma registries, prehospital trauma data are often missing or unreliable because of the difficult dual task consigned to prehospital providers of recording vital signs and simultaneously resuscitating patients. The purpose of this study was to test the hypothesis that the analysis of continuous vital signs acquired automatically, without prehospital provider input, improves vital signs data quality, captures more extreme values that might be missed with conventional human data recording, and changes Trauma Injury Severity Scores compared with retrospectively compiled prehospital trauma registry data. METHODS A statewide vital signs collection network in 6 medevac helicopters was deployed for prehospital vital signs acquisition using a locally built vital signs data recorder (VSDR) to capture continuous vital signs from the patient monitor onto a memory card. VSDR vital signs data were assessed by 3 raters, and intraclass correlation coefficients were calculated to test interrater reliability. Agreement between VSDR and trauma registry data was compared with the methods of Altman and Bland including corresponding calculations for precision and bias. RESULTS Automated prehospital continuous VSDR data were collected in 177 patients. There was good agreement between the first recorded vital signs from the VSDR and the trauma registry value. Significant differences were observed between the highest and lowest heart rate, systolic blood pressure, and pulse oximeter from the VSDR and the trauma registry data (P< .001). Trauma Injury Severity Scores changed in 12 patients (7%) when using data from the VSDR. CONCLUSION Real-time continuous vital signs monitoring and data acquisition can identify dynamic prehospital changes, which may be missed compared with vital signs recorded manually during distinct prehospital intervals. In the future, the use of automated vital signs trending may improve the quality of data reported for inclusion in trauma registries. These data may be used to develop improved triage algorithms aimed at optimizing resource use and enhancing patient outcomes.