Julio Lairet

Prehospital Interventions Performed in a Combat Zone: A Prospective Multicenter Study of 1,003 Combat Wounded

BACKGROUND Battlefield care given to a casualty before hospital arrival impacts clinical outcomes. To date, the published data regarding care given in the prehospital setting of a combat zone are limited. The purpose of this study was to describe the incidence and efficacy of specific prehospital lifesaving interventions (LSIs; interventions that could affect the outcome of the casualty), consistent with the Tactical Combat Casualty Care paradigm, performed during the resuscitation of casualties in a combat zone. METHODS We performed a prospective observational study between November 2009 and November 2011. Casualties were enrolled as they were treated at six US surgical facilities in Afghanistan. Descriptive data were collected on a standardized data collection form and included mechanism of injury, airway management, chest and hemorrhage interventions, vascular access, type of fluid administered, and hypothermia prevention. On arrival to the military hospital, the treating physician determined whether an intervention was performed correctly and whether an intervention was not performed that should have been performed (missed LSI). RESULTS A total of 1,003 patients met the inclusion criteria. Their mean (SD) age was 25 (8.5) years and 97% were male. The mechanism of injury was explosion in 60% of patients, penetrating in 24% of patients, blunt in 15% of patients, and burn in 0.8% of patients. The most commonly performed LSIs included hemorrhage control (n = 599), hypothermia prevention (n = 429), and vascular access (n = 388). Of the missed LSIs, 252 were identified with the highest percentage of missed opportunities being composed of endotracheal intubation, chest needle decompression, and hypotensive resuscitation. In contrast, tourniquet application had the lowest percentage of missed opportunities. CONCLUSIONS In our prospective study of prehospital LSIs performed in a combat zone, we observed a higher rate of incorrectly performed and missed LSIs in airway and chest (breathing) interventions than hemorrhage control interventions. The most commonly performed LSIs had lower incorrect and missed LSI rates. LEVEL OF EVIDENCE Prognostic study, level III.

Hydroxocobalamin and sodium thiosulfate versus sodium nitrite and sodium thiosulfate in the treatment of acute cyanide toxicity in a swine (Sus scrofa) model.

STUDY OBJECTIVE Cyanide can cause severe hypotension with acute toxicity. To our knowledge, no study has directly compared hydroxocobalamin and sodium nitrite with sodium thiosulfate in an acute cyanide toxicity model. Our objective is to compare the return to baseline of mean arterial blood pressure between 2 groups of swine with acute cyanide toxicity and treated with hydroxocobalamin with sodium thiosulfate or sodium nitrite with sodium thiosulfate. METHODS Twenty-four swine were intubated, anesthetized, and instrumented (continuous arterial and cardiac output monitoring) and then intoxicated with a continuous cyanide infusion until severe hypotension. The animals were divided into 2 arms of 12 each and then randomly assigned to intravenous hydroxocobalamin (150 mg/kg)+sodium thiosulfate (413 mg/kg) or sodium nitrite (10 mg/kg)+sodium thiosulfate (413 mg/kg) and monitored for 40 minutes after start of antidotal infusion. Twenty animals were needed for 80% power to detect a significant difference in outcomes (alpha 0.05). Repeated measures of analysis of covariance and post hoc t test were used for determining significance. RESULTS Baseline mean weights, time to hypotension (31 minutes 3 seconds versus 28 minutes 6 seconds), and cyanide dose at hypotension (5.6 versus 5.9 mg/kg) were similar. One animal in the hydroxocobalamin group and 2 animals in the sodium nitrite group died during antidote infusion and were excluded from analysis. Hydroxocobalamin resulted in a faster return to baseline mean arterial pressure, with improvement beginning at 5 minutes and lasting through the conclusion of the study (P<.05). No statistically significant difference was detected between groups for cardiac output, pulse rate, systemic vascular resistance, or mortality at 40 minutes post intoxication. Mean cyanide blood levels (4.03 versus 4.05 microg/mL) and lactate levels (peak 7.9 versus 8.1 mmol/L) at hypotension were similar. Lactate levels (5.1 versus 4.48 mmol/L), pH (7.40 versus 7.37), and base excess (-0.75 versus 1.27) at 40 minutes were also similar. CONCLUSION Hydroxocobalamin with sodium thiosulfate led to a faster return to baseline mean arterial pressure compared with sodium nitrite with sodium thiosulfate; however, there was no difference between the antidote combinations in mortality, serum acidosis, or serum lactate.

Hydroxocobalamin Versus Sodium Thiosulfate for the Treatment of Acute Cyanide Toxicity in a Swine (Sus scrofa) Model

STUDY OBJECTIVE We compare the efficacy of hydroxocobalamin to sodium thiosulfate to reverse the depressive effects on mean arterial pressure in a swine model of acute cyanide toxicity and gain a better understanding of the mechanism of action of the hydroxocobalamin in reversal of the toxicity. METHODS Swine were intubated, anesthetized, and instrumented with central arterial and venous lines and a pulmonary artery catheter. Animals (n=36) were randomly assigned to one of 3 groups: hydroxocobalamin alone (150 mg/kg), sodium thiosulfate alone (413 mg/kg), or hydroxocobalamin (150 mg/kg)+sodium thiosulfate (413 mg/kg) and monitored for 60 minutes after the start of antidotal infusion. Cyanide was infused until severe hypotension developed, defined as blood pressure 50% of baseline mean arterial pressure. Repeated-measures ANOVA was used to determine statistically significant changes between groups over time. RESULTS Time to hypotension (25, 28, and 33 minutes), cyanide dose at hypotension (4.7, 5.0, and 5.6 mg/kg), and mean cyanide blood levels (3.2, 3.7, and 3.8 μg/mL) and lactate levels (7, 8.2, 8.3 and mmol/L) were similar. All 12 animals in the sodium thiosulfate group died compared with 2 of 12 in the hydroxocobalamin/sodium thiosulfate group and 1 of 12 in hydroxocobalamin group. No statistically significant differences were detected between the hydroxocobalamin and hydroxocobalamin/sodium thiosulfate groups for carbon monoxide, mean arterial pressure, cyanide levels, or mortality at 60 minutes. Lactate level (2.6 versus 2.1 mmol/L), pH (7.44 versus 7.42), and bicarbonate level (25 versus 26 mEq/L) at 60 minutes were also similar between groups. CONCLUSION Sodium thiosulfate failed to reverse cyanide-induced shock in our swine model of severe cyanide toxicity. Further, sodium thiosulfate was not found to be effective when added to hydroxocobalamin in the treatment of cyanide-induced shock. Hydroxocobalamin alone was again found to be effective for severe cyanide toxicity.

Short-term Outcomes of US Air Force Critical Care Air Transport Team (CCATT) Patients Evacuated from a Combat Setting

Abstract Purpose. The purpose of this study is to describe the short-term outcomes (during air transport) of patients managed by the United States Air Force Critical Care Air Transport Teams (CCATT). Methods. This is a retrospective chart review of patients who were transported by CCATT between March 1, 2007 and June 30, 2008. A standardized abstraction form was used. Patients were classified as medical or trauma. Care given inflight was documented, including mechanical ventilation, vasoactive medication administration, and administration of blood products. Short-term events (during air transport) included death, oxyhemoglobin desaturation, hypotension, decline in neurological status, development of anuria or oliguria, and dislodgement of endotracheal and chest tubes. Results. A total of 656 patient moves met inclusion criteria, of which 425 (64.8%) were trauma and 231 (35.2%) were medical. Mechanical ventilation was required by 318 (49%), 68 (10%) received vasoactive medications, and 43 (7%) required blood products during the flight. There were a total of 75 events documented on 65 patient transports (10%). Of these, 19 were oxyhemoglobin desaturation, 29 were hypotension, 3 were decline in neurological status, and 23 were due to anuria or oliguria. We did not encounter any deaths or loss of airway or chest tubes during transport. Conclusion. CCATTs are a successful platform in transporting critically injured/ill patients with minimal short-term complications. Key Words: Critical Care Air Transport; emergency medical services; prehospital; resuscitation; tactical combat casualty care

A Comparison of Proximal Tibia, Distal Femur, and Proximal Humerus Infusion Rates Using the EZ-IO Intraosseous Device on the Adult Swine (Sus scrofa) Model

Abstract Objective. We sought to compare the flow rates of the proximal tibia, the distal femur, and the proximal humerus using high pressure (greater than 300 mmHg) through an intraosseous (IO) infusion needle in an adult swine model. Methods. We performed a prospective interventional study in 11 swine. After placement of central vein and arterial lines, blood was removed via the central line until the animals mean arterial pressure decreased 25% from the recorded baseline. We inserted a 25-mm IO needle into the proximal tibia and 45-mm needles into the distal femur and proximal humerus. All extremities were utilized in each study animal. We infused normal saline at each site for 10 minutes with a pressure bag inflated to the highest achievable pressure (greater than 300 mmHg) as measured at the infusion site with a calibrated portable inline pressure gauge. We measured the volume of normal saline remaining and we calculated infusion rates for each site. We then compared infusion flow rates between the three locations. Statistical analysis and comparison of the infusion rates of all three study arms were as performed using analysis of variance (ANOVA). Results. The average weight of the swine was 71 kg (range 64–84 kg). Successful placement of the IO needle was confirmed at all three sites. The mean infusion flow rate was 213 mL/min (standard deviation [SD] 53.2 mL/min) for the proximal humerus, 138 mL/min (SD 65.3 mL/min) for the distal femur, and 103 mL/min (SD 48.1 mL/min) for the proximal tibia (p < 0.001). The flow rate through the proximal humerus was statistically greater than that for the proximal tibia and the distal femur (p < 0.001). The flow rates through the proximal tibia and distal femur were similar. Conclusion. The humerus is a suitable alternative site for IO placement, with a potential for higher flow rates than the proximal tibia and distal femur when resuscitating a patient. Key words: intraosseous; prehospital; resuscitation; tactical combat casualty care; emergency medical services

Prehospital Burn Management in a Combat Zone

Abstract Objective. The purpose of this article is to provide a descriptive study of the management of burns in the prehospital setting of a combat zone. Methods. A retrospective chart review was performed of U.S. casualties with >20% total-body-surface-area thermal burns, transported from the site of injury to Ibn Sina Combat Support Hospital (CSH) between January 1, 2006, and August 30, 2009. Results. Ibn Sina CSH received 225 burn casualties between January 2006 and August 2009. Of these, 48 met the inclusion criteria. The mean Injury Severity Score was 31.7 (range 4 to 75). Prehospital vascular access was obtained in 24 casualties (50%), and 20 of the casualties received fluid resuscitation. Out of the 48 casualties enrolled, 28 (58.3%) did not receive prehospital fluid resuscitation. Of the casualties who received fluid resuscitation, nearly all received volumes in excess of the guidelines established by the American Burn Association and those recommended by the Committee for Tactical Combat Casualty Care. With regard to pain management in the prehospital setting, 13 casualties (27.1%) received pain medication. Conclusions. With regard to the prehospital fluid resuscitation of primary thermal injury in the combat zone, two extremes were noted. The first group did not receive any fluid resuscitation; the second group was resuscitated with fluid volumes higher than those expected if established guidelines were utilized. Pain management was not uniformly provided to major burn casualties, even in several with vascular access. These observations support improved education of prehospital personnel serving in a combat zone.

The Incidence of Fever in US Critical Care Air Transport Team Combat Trauma Patients Evacuated From the Theater Between March 2009 and March 2010

INTRODUCTION Most critically ill injured patients are transported out of the theater by Critical Care Air Transport Teams (CCATTs). Fever after trauma is correlated with surgical complications and infection. The purposes of this study are to identify the incidence of elevated temperature in patients managed in the CCATT environment and to describe the complications reported and the treatments used in these patients. METHODS We performed a retrospective review of available records of trauma patients from the combat theater between March 1, 2009, and March 31, 2010, who were transported by the US Air Force CCATT and had an incidence of hyperthermia. We then divided the cohort into 2 groups, patients transported with an elevation in temperature greater than 100.4°F and patients with no documented elevation in temperature. We used a standardized, secure electronic data collection form to abstract the outcomes. Descriptive data collected included injury type, temperature, use of a mechanical ventilator, cooling treatment modalities, antipyretics, intravenous fluid administration, and use of blood products. We also evaluated the incidence of complications during the transport in patients who had a recorded elevation in temperature greater than 100.4°F. RESULTS A total of 248 trauma patients met the inclusion criteria, and 101 trauma patients (40%) had fever. The mean age was 28 years, and 98% of patients were men. The mechanism of injury was an explosion in 156 patients (63%), blunt injury in 11 (4%), and penetrating injury in 45 (18%), whereas other trauma-related injuries accounted for 36 patients (15%). Of the patients, 209 (84%) had battle-related injuries and 39 (16%) had non-battle-related injuries. Traumatic brain injury was found in 24 patients (24%) with an incidence of elevated temperature. The mean temperature was 101.6°F (range, 100.5°F-103.9°F). After evaluation of therapies and treatments, 80 trauma patients (51%) were intubated on a mechanical ventilator (P < .001). Of the trauma patients with documented fever, 22 (22%) received administration of blood products. Nineteen patients received antipyretics during their flight (19%), 9 received intravenous fluids (9%), and 2 received nonpharmacologic cooling interventions, such as cooling blankets or icepacks. We identified 1 trauma patient with neurologic changes (1%), 6 with hypotension (6%), 48 with tachycardia (48%), 33 with decreased urinary output (33%), and 1 with an episode of shivering or sweating (1%). We did not detect any transfusion reactions or deaths during flight. CONCLUSION Fever occurred in 41% of critically ill combat-injured patients evacuated out of the combat theater in Iraq and Afghanistan. Fewer than 20% of patients with a documented elevated temperature received treatments to reduce the temperature. Intubation of patients with ventilators in use during the transport was the only factor significantly associated with fever. Serious complications were rare, and there were no deaths during these transports.