Charles M. Little

The ultrasonic detection of soft tissue foreign bodies.

The ability of B-scan ultrasonography to detect soft tissue foreign bodies of various sizes and composition was investigated in a canine model. Foreign bodies consisting of wooden rods 0.7 mm and larger, lead-free glass rods 2.0 mm and larger, plastic rods 3.9 mm and 5.6 mm, and metal needles 0.5 mm and larger were embedded in fleshy soft tissue. All objects examined were discernible. Wood is best visualized followed by glass, plastic, and metal. Ultrasound may be a valuable noninvasive means of detecting soft tissue foreign bodies; further investigation to delineate its clinical role is warranted.

The incidence of vasculature at risk during cricothyroidostomy

In this study, the region anterior to the cricothyroid membrane of 34 adult cadavers was dissected. Vascular patterns, including vessel type, diameter, and position were recorded. Twenty-seven cadavers (79%) had vascular structures within this area. Twenty-one (62%) had vertically oriented arteries or veins that would be at risk during cricothyroidostomy.

Hydroxocobalamin and Epinephrine Both Improve Survival in a Swine Model of Cyanide-Induced Cardiac Arrest

STUDY OBJECTIVE To determine whether hydroxocobalamin will improve survival compared with epinephrine and saline solution controls in a model of cyanide-induced cardiac arrest. METHODS Forty-five swine (38 to 42 kg) were tracheally intubated, anesthetized, and central venous and arterial continuous cardiovascular monitoring catheters were inserted. Potassium cyanide was infused until cardiac arrest developed, defined as mean arterial pressure less than 30 mm Hg. Animals were treated with standardized mechanical chest compressions and were randomly assigned to receive one of 3 intravenous bolus therapies: hydroxocobalamin, epinephrine, or saline solution (control). All animals were monitored for 60 minutes after cardiac arrest. Additional epinephrine infusions were used in all arms of the study after return of spontaneous circulation for systolic blood pressure less than 90 mm Hg. A sample size of 15 animals per group was determined according to a power of 80%, a survival difference of 0.5, and an α of 0.05. Repeated-measure ANOVA was used to determine statistically significant changes between groups over time. RESULTS Baseline weight, time to arrest, and cyanide dose at cardiac arrest were similar in the 3 groups. Coronary perfusion pressures with chest compressions were greater than 15 mm Hg in both treatment groups indicating sufficient compression depth. Zero of 15 (95% confidence interval [CI] 0% to 25%) animals in the control group, 11 of 15 (73%; 95% CI 48% to 90%) in the hydroxocobalamin group, and 11 of 15 (73%; 95% CI 48% to 90%) in the epinephrine group survived to the conclusion of the study (P<.001). The proportion of animals with return of spontaneous circulation at 5 minutes was 4 of 15 (27%; 95% CI 10% to 52%), and that of return of spontaneous circulation at 10 minutes was 11 of 15 (73%; 95% CI 48% to 90%) in the 2 treatment groups. Additional epinephrine infusion after return of spontaneous circulation was administered for hypotension in 2 of 11 (18%; 95% CI 4% to 48%) hydroxocobalamin animals and in 11 of 11 (100%; 95% CI 70% to 100%) of the epinephrine animals (P<.001). At 60 minutes, serum lactate was significantly lower in the hydroxocobalamin group compared with the epinephrine group (4.9 [SD 2.2] versus 12.3 [SD 2.2] mmol/L), and the pH was significantly higher (7.34 [SD 0.03] versus 7.15 [SD 0.07]). Serial blood cyanide levels in the hydroxocobalamin group were also lower than that of the epinephrine group from cardiac arrest through the conclusion of the study. CONCLUSION Intravenous hydroxocobalamin and epinephrine both independently improved survival compared with saline solution control in our swine model of cyanide-induced cardiac arrest. Hydroxocobalamin improved mean arterial pressure and pH, decreased blood lactate and cyanide levels, and decreased the use of rescue epinephrine therapy compared with that in the epinephrine group.

A swine model of pseudo-pulseless electrical activity induced by partial asphyxiation

BACKGROUND The incidence of pulseless electrical activity (PEA) as a presenting rhythm during cardiac arrest is increasing. The current animal models of PEA arrest, post-countershock or total asphyxiation, unreliably generate PEA for a specific time period. Neither of these models predictably generate pseudo-PEA. The purpose of this study was to create an animal model of pseudo-PEA that will allow for a prolonged time period in this arrest state for future research. METHODS In a laboratory setting, five ventilated swine on inhaled anesthesia and 100% oxygen with continuous EKG recordings were instrumented with central aortic and venous pressure-transducing catheters. Animals were then switched to intravenous anesthesia while being ventilated with a 16% oxygen/84% nitrogen mix. Continuous EKG, aortic and venous pressures were recorded to a computerized data collection program. Arterial blood gas samples were taken every 10min. Time until onset of pseudo-PEA, duration of pseudo-PEA, and cardiac rhythm during pseudo-PEA were recorded. RESULTS Mean time to onset of pseudo-PEA was 80.6+/-47.3min. Mean duration of pseudo-PEA was 18.6+/-6.2min. Mean arterial pH at pseudo-PEA onset was 7.20+/-0.05 with a mean associated base excess of -11.4+/--5.94. No significant differences were noted in other recorded variables. CONCLUSIONS Partial asphyxiation using a 16% oxygen/84% nitrogen mix is a reliable laboratory method to create a prolonged state of pseudo-PEA in a swine model. The mechanism generating pseudo-PEA is hypoxemia-induced systemic acidosis. This model will allow sufficient time in this low-flow cardiac state for future research to be conducted.

A novel hands-free carotid ultrasound detects low-flow cardiac output in a swine model of pulseless electrical activity arrest

OBJECTIVE To determine if a hands-free, noninvasive Doppler ultrasound device can reliably detect low-flow cardiac output by measuring carotid artery blood flow velocities. We compared the ability of observers to detect carotid artery flow velocity differences between pseudo-pulseless electrical activity (PEA) and true-PEA cardiac arrest. METHODS Five swine were instrumented with aortic (Ao) and right atrial pressure-transducing catheters. The Doppler ultrasound device was adhered to the neck over the carotid artery. Continuous electrocardiogram, pressure readings, and Doppler signal were recorded. Each swine underwent multiple episodes of fibrillation and resuscitation. Episodes of true-PEA and pseudo-PEA were retrospectively identified from all resuscitation attempts by examination of electrocardiogram and Ao waveforms. The sensitivity and specificity of the device to detect pseudo-PEA was obtained using observers blinded to Ao waveform recordings. RESULTS There was good interobserver reliability related to identification of pseudo- and true-PEA (κ = 0.873). The observers blinded to Ao waveform recordings agreed on 8 of the 9 episodes of pseudo-PEA, whereas 4 false positives of 26 true-PEA events were reported (sensitivity, 0.89; specificity, 0.85). The Doppler device was able to detect carotid flow velocity over a wide range of Ao blood pressures. CONCLUSIONS This hands-free, noninvasive Doppler ultrasound device can reliably differentiate pseudo-PEA from true-PEA during resuscitation from cardiac arrest, detecting pressure gradient changes of less than 5 mm Hg through to normotension. This device distinguishes conditions of no cardiac output from low cardiac output and may have applications for use during resuscitation from various etiologies of arrest and shock.

Vulnerable Populations in Hospital and Health Care Emergency Preparedness Planning: A Comprehensive Framework for Inclusion.

INTRODUCTION As attention to emergency preparedness becomes a critical element of health care facility operations planning, efforts to recognize and integrate the needs of vulnerable populations in a comprehensive manner have lagged. This not only results in decreased levels of equitable service, but also affects the functioning of the health care system in disasters. While this report emphasizes the United States context, the concepts and approaches apply beyond this setting. OBJECTIVE This report: (1) describes a conceptual framework that provides a model for the inclusion of vulnerable populations into integrated health care and public health preparedness; and (2) applies this model to a pilot study. METHODS The framework is derived from literature, hospital regulatory policy, and health care standards, laying out the communication and relational interfaces that must occur at the systems, organizational, and community levels for a successful multi-level health care systems response that is inclusive of diverse populations explicitly. The pilot study illustrates the application of key elements of the framework, using a four-pronged approach that incorporates both quantitative and qualitative methods for deriving information that can inform hospital and health facility preparedness planning. CONCLUSIONS The conceptual framework and model, applied to a pilot project, guide expanded work that ultimately can result in methodologically robust approaches to comprehensively incorporating vulnerable populations into the fabric of hospital disaster preparedness at levels from local to national, thus supporting best practices for a community resilience approach to disaster preparedness.

Preparing Emergency Physicians for Acute Disaster Response: A Review of Current Training Opportunities in the US.

Study Objective This study aimed to review available disaster training options for health care providers, and to provide specific recommendations for developing and delivering a disaster-response-training program for non-disaster-trained emergency physicians, residents, and trainees prior to acute deployment. METHODS A comprehensive review of the peer-reviewed and grey literature of the existing training options for health care providers was conducted to provide specific recommendations. RESULTS A comprehensive search of the Pubmed, Embase, Web of Science, Scopus, and Cochrane databases was performed to identify publications related to courses for disaster preparedness and response training for health care professionals. This search revealed 7,681 unique titles, of which 53 articles were included in the full review. A total of 384 courses were found through the grey literature search, and many of these were available online for no charge and could be completed in less than six hours. The majority of courses focused on management and disaster planning; few focused on clinical care and acute response. CONCLUSION There is need for a course that is targeted toward emergency physicians and trainees without formal disaster training. This course should be available online and should utilize a mix of educational modalities, including lectures, scenarios, and virtual simulations. An ideal course should focus on disaster preparedness, and the clinical and non-clinical aspects of response, with a focus on an all-hazards approach, including both terrorism-related and environmental disasters. Hansoti B , Kellogg DS , Aberle SJ , Broccoli MC , Feden J , French A , Little CM , Moore B , Sabato J Jr. , Sheets T , Weinberg R , Elmes P , Kang C . Preparing emergency physicians for acute disaster response: a review of current training opportunities in the US. Prehosp Disaster Med. 2016;31(6):643-647.