Performance comparison of intraosseous devices and setups for infusion of whole blood in a cadaveric swine bone model.

OBJECTIVES: Intraosseous (IO) access can provide a critical bridge for blood product infusion when peripheral venous access is not obtainable. Successful pressurized IO infusion requires flow rates sufficient to preserve life, but with infusion pressures low enough to avoid clinical complications (e.g., hemolysis, bone damage, fat emboli). However, the optimal method for pressured IO delivery of blood was unknown. METHODS: Three trained physicians infused 500 mL of whole blood through a 15-gauge, 45 mm IO catheter into fresh, high bone density cadaveric swine proximal humeri. Participants applied eight different pressure infusion strategies: (1) gravity, (2) pressure bag, (3) pressure bag actively maintained at or above 300 mmHg, (4) hand pump, (5) hand pump with pressure bag, (6) push-pull with 10 mL syringe, (7) push-pull with 60 mL syringe, and a (8) Manual Rapid Infuser in a randomized within-subjects design (30 trials per method, 240 trials total). The primary outcomes of flow rates, mean and peak pressures, and user ratings were contrasted using ANOVA at p < 0.05. RESULTS: The Manual Rapid Infuser conferred the highest flow rates (199 ± 3 mL/min) and most favorable user ratings, but also the highest mean and peak pressures. Push-pull conferred the next highest flow rates (67 ± 5 mL/min for 60 mL, 56 ± 2 mL/min for 10 mL) and pressures, with intermediate-to-high user ratings. Hand pump flow rates were essentially identical with (45 ± 4 mL/min) or without (44 ± 3 mL/min) pressure bag, with high user ratings without a pressure bag. Pressure bag and gravity methods conferred low flow rates and user ratings. CONCLUSIONS: Some pressured IO infusion methods can achieve flow rates adequate to serve as a resuscitative bridge in the massively hemorrhaged trauma victim, but flow rates and pressures vary greatly across IO pressurized infusion methods. Manual Rapid Infuser and push-pull methods conferred high flow rates but also relatively high pressures, highlighting the importance of using in vivo models in future research to assess the possible clinical complications of using these promising methods. Combined, present findings highlight the importance of studying pressurized IO methods towards preserving the life of the critically injured trauma victim.

Single Versus Double Anatomic Site Intraosseous Blood Transfusion in a Swine Model of Hemorrhagic Shock.

BACKGROUND: Blood transfusion via single site intraosseous access is a critical modality when caring for a trauma victim that lacks intravascular access. Flow rates and potential clinical complications when utilizing two sites of intraosseous access are not well known. MATERIALS AND METHODS: Anesthetized adult female Yorkshire swine (Sus scrofa; n = 48; 76.7 ± 1.75kg; range 66-90kg) were cannulated and then bled approximately 30% total blood volume. Swine were randomly assigned to treatment groups: single sited humerus, single sited sternum, dual sited humerus or dual sited humerus and sternum. Flow rates, hemolysis, physiologic measurements, biochemical variables, and pulmonary histologic inflammation and occlusion were contrasted between groups. RESULTS: Dual sited intraosseous transfusion flow rates (128ml/min, 95% CI 123-132) were double the flow rates of single sites (65ml/min, 95% CI 60-70), P < .0001.Single sited humeral flow rates were greater than sternal flow rates, with respective averages of 74ml/min and 55ml/min, though not reaching statistical significance (P < 0.17). There was no significant elevation of plasma free hemoglobin in any group after transfusion as compared to baseline (P = 0.7). Groups did not significantly differ in vitals or biochemical variables. Most pulmonary specimens had some intraparenchymal fat embolism, however no animals had evidence of occlusive intra-arterial fat embolism. CONCLUSIONS: Dual anatomic site, pressure bag driven, intraosseous blood transfusion approximately doubles flow rates without evidence of clinical complications or hemolysis. Further research using a survivability model is needed to characterize long-term complications from pressurized IO transfusions.

Renal angiomyolipoma rupture in a young female with COVID-19.

While primarily a respiratory illness, infection with the novel coronavirus (COVID-19) is associated with pathologic changes in coagulation, characterized by both thromboembolic and bleeding events. We present the case of a 22-year-old female diagnosed with renal angiomyolipoma (AML) rupture 2 weeks after COVID-19 infection, ultimately requiring admission for hemorrhage control via endovascular embolization. Emergency medicine physicians should maintain a high index of suspicion for renal AML rupture and other spontaneous bleeding events in patients with recent COVID-19 infection due to a possible correlation between the two.

Revitalizing a vital sign: improving detection of tachypnea at primary triage.

STUDY OBJECTIVE: This study evaluates the accuracy of emergency department (ED) triage respiratory rate measurement using the usual care method and a new electronic respiratory rate sensor (BioHarness, Zephyr Technology Corp.), both compared to a criterion standard measurement. METHODS: This is a cross-sectional study with convenience sampling conducted in an urban academic adult ED, including 3 separate respiratory rate measurements performed at ED triage: usual care measurement, electronic BioHarness measurement, and criterion standard measurement. The criterion standard measurement used was defined by the World Health Organization as manual observation or auscultation of respirations for 60 seconds. The resultant usual care and BioHarness measurements were compared with the criterion standard, evaluating accuracy (sensitivity and specificity) for detecting tachypnea, as well as potential systematic biases of usual care and BioHarness measurements using a Bland Altman analysis. RESULTS: Of 191 analyzed patients, 44 presented with tachypnea (>20 breaths/min). Relative to criterion standard measurement, usual care measurement had a sensitivity of 23% (95% confidence interval [CI] 12% to 37%) and specificity of 99% (95% CI 97% to 100%) for tachypnea, whereas BioHarness had a sensitivity of 91% (95% CI 80% to 97%) and specificity of 97% (95% CI 93% to 99%) for tachypnea. Usual care measurements clustered around respiratory rates of 16 and 18 breaths/min (n=144), with poor agreement with criterion standard measurement. Conversely, BioHarness measurement closely tracked criterion standard values over the range of respiratory rates. CONCLUSION: Current methods of respiratory rate measurement at ED triage are inaccurate. A new electronic respiratory rate sensor, BioHarness, has significantly greater sensitivity for detecting tachypnea versus usual care method of measurement.

Evacuation of Non-ST Elevation Myocardial Infarction in West Africa: 19 Hours of Lessons Learned in Prolonged Casualty Care and En Route Care.

Trauma casualty care has historically been the cornerstone of special operations military medical training. A recent case of myocardial infarction at a remote base of operations in Africa highlights the importance of foundational medical knowledge and training. A 54-year-old government contractor supporting operations in the AFRICOM area of responsibility (AOR) presented to the Role 1 medic with substernal chest pain with onset during exercise. Abnormal rhythm strips concerning for ischemia were obtained from his monitors. A MEDEVAC to a Role 2 facility was arranged and executed. At the Role 2 a non-ST-elevation myocardial infarction (NSTEMI) was diagnosed. The patient was emergently evacuated on a lengthy flight to a civilian Role 4 treatment facility for definitive care. He was found to have a 99% occlusion of the left anterior descending (LAD) coronary artery, as well as a 75% occlusion of the posterior coronary artery and a chronic 100% occlusion of the circumflex artery. The LAD and posterior arteries were stented, and the patient made a favorable recovery. This case highlights the importance of preparedness for medical emergencies and care of medically critical patients in remote and austere locations.

Determining Intraosseous Needle Placement Using Point-of-Care Ultrasound in a Swine (Sus scrofa) Model.

OBJECTIVE: Intraosseous (IO) access is critical in resuscitation, providing rapid access when peripheral vascular attempts fail. Unfortunately, misplacement commonly occurs, leading to possible fluid extravasation and tissue necrosis. Current research exploring the utility of bedside ultrasound in confirming IO line placement is limited by small sample sizes of skeletally immature subjects or geriatric cadaveric models. The objective of this study was to investigate the potential value of ultrasound confirming IO needle placement in a live tissue model with bone densities approximated to the young adult medical or trauma patient. MATERIALS AND METHODS: In this randomized, blinded prospective study, IO devices were placed into the bilateral humeri of 36 sedated adult swine (N = 72) with bone densities approximating that of a 20-39-year-old adult. Of the 72 lines, 53 were randomized to the IO space ("correct") and 19 into the subcutaneous tissue ("incorrect"). Four emergency physicians with variable ultrasound experience and blinded to needle location independently assessed correct or incorrect needle placements based on the presence of an intramedullary "flare" on color power Doppler (CPD) during a saline flush. Participants adjusted the ultrasound beam trajectory and recorded assessments up to three times, totaling 204 separate observations. RESULTS: Overall, sensitivity for placement confirmation was 72% (95% CI: 64%-79%). Specificity was 79% (95% CI: 66%-89%). First assessment and final assessment results were similar. More experienced sonographers demonstrated greater success in identifying inaccurate placements with a specificity of 86% (95% CI: 63%-96%). CONCLUSION: Within the context of this study, point-of-care ultrasound with CPD did not reliably confirm IO line placement. However, more accurate assessments of functional and malpositioned catheters were noted in sonographers with greater than 4 years of experience. Future study into experienced sonographers' use of CPD to confirm IO catheter placement is needed.

Ultrasound Localization of Resuscitative Endovascular Balloon Occlusion of the Aorta in a Human Cadaver Model.

OBJECTIVE: Resuscitative endovascular balloon occlusion of the aorta (REBOA) is a method of gaining proximal control of noncompressible torso hemorrhage (NCTH). Catheter placement is traditionally confirmed with fluoroscopy, but few studies have evaluated whether ultrasound (US) can be used. METHODS: Using a pressurized human cadaver model, a certified REBOA placer was shown one of four randomized cards that instructed them to place the REBOA either correctly or incorrectly in Zone 1 (the distal thoracic aorta extending from the celiac artery to the left subclavian artery) or Zone 3 (in the distal abdominal aorta, from the aortic bifurcation to the lowest renal artery). Once the REBOA was placed, 10 US-trained locators were asked to confirm balloon placement via US. The participants were given 3 minutes to determine whether the catheter had been correctly placed, repeating this 20 times on two cadavers. RESULTS: Overall, US exhibited an average sensitivity of 83%, specificity of 76%, and accuracy of 80%. For Zone 1, US showed a sensitivity of 78% and specificity of 83%, and for Zone 3, a sensitivity of 88% and specificity of 76%. In addition, US exhibited a likelihood positive ratio (LR+) of 3.73 and a likelihood negative ratio (LR-) of 0.22 for either position, with similar numbers for Zone 1 (+4.57, -0.26) and Zone 3 (+3.16, -0.16). CONCLUSION: Ultrasound could prove to be a useful tool for confirming placement of a REBOA catheter, especially in austere environments.

Rapid Sequence Induction Strategies Among Critically Injured U.S. Military During the Afghanistan and Iraq Conflicts.

INTRODUCTION: Rapid sequence intubation of patients experiencing traumatic hemorrhage represents a precarious phase of care, which can be marked by hemodynamic instability and pulseless arrest. Military combat trauma guidelines recommend reduced induction dose and early blood product resuscitation. Few studies have evaluated the role of induction dose and preintubation transfusion on hemodynamic outcomes. We compared rates of postintubation systolic blood pressure (SBP) of < 70 mm Hg, > 30% drop in SBP, pulseless arrest, and mortality at 24 hours and 30 days among patients who did and did not receive blood products before intubation and then examined if induction agent and dose influenced the same outcomes. MATERIALS AND METHODS: A retrospective analysis was performed of battle-injured personnel presenting to surgical care facilities in Iraq and Afghanistan between 2004 and 2018. Those who received blood transfusions, underwent intubation, and had an Injury Severity Score of ≥15 were included. Intubation for primary head, facial, or neck injury, burns, operative room intubations, or those with cardiopulmonary resuscitation in progress were excluded. Multivariable logistic regression was performed with unadjusted and adjusted odds ratios for the five study outcomes among patients who did and did not receive preintubation blood products. The same analysis was performed for patients who received full or excessive versus partial induction agent dose. RESULTS: A total of 153 patients had a mean age of 24.9 (SD 4.5), Injury Severity Score 29.7 (SD 11.2), heart rate 122.8 (SD 24), SBP 108.2 (SD 26.6). Eighty-one (53%) patients received preintubation blood products and had similar characteristics to those who did not receive transfusions. Adjusted multivariate analysis found odds ratios as follows: 30% SBP decrease 9.4 (95% CI 2.3-38.0), SBP < 70 13.0 (95% CI 3.3-51.6), pulseless arrest 18.5 (95% CI 1.2-279.3), 24-hour mortality 3.8 (95% CI 0.7-21.5), and 30-day mortality 1.3 (0.4-4.7). In analysis of induction agent choice and comparison of induction agent dose, no statistically significant benefit was seen. CONCLUSION: Within the context of this historical cohort, the early use of blood products conferred a statistically significant benefit in reducing postintubation hypotension and pulseless arrest among combat trauma victims exposed to traumatic hemorrhage. Induction agent choice and dose did not significantly influence the hemodynamic or mortality outcomes.

Case Series on 2g Tranexamic Acid Flush From the 75th Ranger Regiment Casualty Database.

Early tranexamic acid (TXA) administration for resuscitation of critically injured warfighters provides a mortality benefit. The 2019 Tactical Combat Casualty Care (TCCC) recommendations of a 1g drip over 10 minutes, followed by 1g drip over 8 hours, is intended to limit potential TXA side effects, including hypotension, seizures, and anaphylaxis. However, this slow and cumbersome TXA infusion protocol is difficult to execute in the tactical care environment. Additionally, the side effect cautions derive from studies of elderly or cardiothoracic surgery patients, not young healthy warfighters. Therefore, the 75th Ranger Regiment developed and implemented a 2g intravenous or intraosseous (IV/IO) TXA flush protocol. We report on the first six cases of this protocol in the history of the Regiment. After-action reports (AARs) revealed no incidences of post-TXA hypotension, seizures, or anaphylaxis. Combined, the results of this case series are encouraging and provide a foundation for larger studies to fully determine the safety of the novel 2g IV/IO TXA flush protocol toward preserving the lives of traumatically injured warfighters.

Intravenous and Intraosseous Blood Transfusion With Three Different Pediatric Pressure Transfusion Strategies in an Immature Swine (Sus scrofa) Model of Hemorrhagic Shock: A Pilot Study.

INTRODUCTION: Exsanguination remains the leading cause of preventable death in military conflicts, and pediatric casualties are common. Transfusion is crucial to preserve life, but vascular access is challenging in children, so intraosseous (IO) access is often required. However, the optimal transfusion method is unclear. There was therefore the need for feasibility testing of a model for contrasting the efficacy of blood infusion devices via intravenous (IV) and IO access in immature swine with bone densities similar to children. MATERIALS AND METHODS: Eighteen immature swine (21 ± 1 kg) were bled 31% of estimated blood volume and then received autologous blood delivered by pressure bag, push-pull (PP), or LifeFlow Rapid Infuser via IO (15-gauge IO needle placed in the humeral head) or IV (auricular 20-gauge), with monitoring for 60 minutes. RESULTS: Flow rates for LifeFlow (172 ± 28 mL/kg) were 4-fold higher than pressure bag (44 ± 13 mL/kg, P < 0.001) and 80% higher than PP (95 ± 28 mL/kg, P < 0.02). However, higher hemolysis was evident in the IV LifeFlow condition, with 6-fold more plasma-free hemoglobin than other conditions (P < 0.0001). CONCLUSIONS: IV LifeFlow conferred higher flows, but higher hemolysis in this pilot study demonstrates the feasibility of an immature swine model toward determining optimal methods for resuscitating children with hemorrhagic shock.

Impact of Marine Exposure on Hemostatic Gauzes Using Thromboelastography.

BACKGROUND: Military forces render emergency care in marine environments, where care for exsanguination is challenging. However, the effect of saltwater on the functionality of hemostatic agents is unknown. In this study, we used thromboelastography (TEG) to quantify the effect of saltwater on the efficacy of five gauze products. METHODS: Blood from 24 healthy adult men was diluted by 30% with hetastarch to mimic hemodilution. Dry and saltwater-soaked Kerlix™, ChitoGauze®, Combat Gauze®, NuStat™, and WoundClot™ were contrasted in terms of the TEG parameters of speed of clot initiation (R), clot amplification (K), α angle (i.e., clot formation rate), and maximum amplitude of clot (MA), using repeated-measures analysis of variance at the p < .05 statistical significance threshold. RESULTS: Compared with untreated dilute blood, R was significantly faster when any dry or wet gauze was added, with the fastest R values recorded for Combat Gauze. K and α angle findings were mixed. MA was greater than diluted blood for dry hemostatic gauze, but in the wet condition, only the MA for Combat Gauze was significantly greater than that of diluted blood. CONCLUSION: Gauze products, wet or dry, improved clotting compared to diluted blood without gauze. Saltwater exposure did not significantly detract from this benefit. Our findings suggest that Combat Gauze may be the choice hemostatic gauze for maritime environments.

Osteopathic manipulative treatment for self-reported fatigue, stress, and depression in first-year osteopathic medical students.

CONTEXT: During medical education, many students experience psychological distress, including symptoms such as fatigue, stress, and depression. OBJECTIVE: To evaluate the effect of osteopathic manipulative treatment (OMT) on self-perceived fatigue, stress, and depression in first-year osteopathic medical students. METHODS: This randomized controlled pilot study with repeated measures was conducted at the Lake Erie College of Osteopathic Medicine-Bradenton in Florida during the fall 2012 semester. First-year osteopathic medical students voluntarily enrolled in the study and were randomly assigned to directed OMT (D-OMT), nondirected OMT (ND-OMT), or control groups. The D-OMT and ND-OMT groups received treatment by osteopathic physicians weekly for 4 weeks. The control group received no treatment. All groups completed the Epworth Sleepiness Scale (ESS), the Self-Perceived Stress Scale (SPSS), and the Primary Care Evaluation of Mental Disorders Patient Health Questionnaire 9 (PHQ-9) depression scale before treatment (pretest), after 2 treatments (midtest), and after 4 treatments (posttest). RESULTS: All participants self-reported as white and single, with both sexes equally represented, and had an mean age of 24 years. Analysis of ESS scores revealed a statistically significant decrease in the D-OMT group from pretest and posttest scores and a statistically significant increase in the ND-OMT group from pretest to midtest but not from pretest to posttest scores. No statistically significant differences were noted in the control group scores on this measure. No statistically significant differences were seen in the SPSS or PHQ-9 scores from pretest to midtest or pretest to posttest in any of the 3 groups. CONCLUSION: The D-OMT regimen used in the current study produced a statistically significant decrease in self-perceived fatigue in first-year osteopathic medical students. Osteopathic manipulative treatment represents a potential modality to reduce self-perceived distress in medical students. Further research is warranted.