Amiodarone, Lidocaine, or Placebo in Out-of-Hospital Cardiac Arrest.

BACKGROUND: Antiarrhythmic drugs are used commonly in out-of-hospital cardiac arrest for shock-refractory ventricular fibrillation or pulseless ventricular tachycardia, but without proven survival benefit. METHODS: In this randomized, double-blind trial, we compared parenteral amiodarone, lidocaine, and saline placebo, along with standard care, in adults who had nontraumatic out-of-hospital cardiac arrest, shock-refractory ventricular fibrillation or pulseless ventricular tachycardia after at least one shock, and vascular access. Paramedics enrolled patients at 10 North American sites. The primary outcome was survival to hospital discharge; the secondary outcome was favorable neurologic function at discharge. The per-protocol (primary analysis) population included all randomly assigned participants who met eligibility criteria and received any dose of a trial drug and whose initial cardiac-arrest rhythm of ventricular fibrillation or pulseless ventricular tachycardia was refractory to shock. RESULTS: In the per-protocol population, 3026 patients were randomly assigned to amiodarone (974), lidocaine (993), or placebo (1059); of those, 24.4%, 23.7%, and 21.0%, respectively, survived to hospital discharge. The difference in survival rate for amiodarone versus placebo was 3.2 percentage points (95% confidence interval [CI], -0.4 to 7.0; P=0.08); for lidocaine versus placebo, 2.6 percentage points (95% CI, -1.0 to 6.3; P=0.16); and for amiodarone versus lidocaine, 0.7 percentage points (95% CI, -3.2 to 4.7; P=0.70). Neurologic outcome at discharge was similar in the three groups. There was heterogeneity of treatment effect with respect to whether the arrest was witnessed (P=0.05); active drugs were associated with a survival rate that was significantly higher than the rate with placebo among patients with bystander-witnessed arrest but not among those with unwitnessed arrest. More amiodarone recipients required temporary cardiac pacing than did recipients of lidocaine or placebo. CONCLUSIONS: Overall, neither amiodarone nor lidocaine resulted in a significantly higher rate of survival or favorable neurologic outcome than the rate with placebo among patients with out-of-hospital cardiac arrest due to initial shock-refractory ventricular fibrillation or pulseless ventricular tachycardia. (Funded by the National Heart, Lung, and Blood Institute and others; ClinicalTrials.gov number, NCT01401647.).

An Urban 9-1-1 System's Experience with Left Ventricular Assist Device Patients.

Background: Left ventricular assist devices (LVADs) are used with increasing frequency and left in place for longer periods of time. Prior publications have focused on the mechanics of troubleshooting the device itself. We aim to describe the epidemiology of LVAD patient presentations to emergency medical services (EMS), prehospital assessments and interventions, and hospital outcomes. Methods: This is a retrospective chart review of known LVAD patients that belong to a single academic center's heart failure program who activated the 9-1-1 system and were transported by an urban EMS system to one of the center's 2 emergency departments between January 2012 and December 2015. Identifying demographics were used to query the electronic medical record of the responding city fire agency and contracted transporting ambulance service. Two reviewers abstracted prehospital chief complaint, vital signs, assessments, and interventions. Emergency department and hospital outcomes were retrieved separately. Results: From January 2012 to December 2015, 15 LVAD patients were transported 16 times. The most common prehospital chief complaint was weakness (7/16), followed by chest pain (3/16). Of the 7 patients presenting with weakness, one was diagnosed with a stroke in the emergency department. Another patient was diagnosed with subarachnoid hemorrhage and expired during hospital admission. This was the only death in the cohort. The most common hospital diagnosis was GI bleed (3/16). The overall admission rate was 87.5% (14/16). Conclusions: EMS interactions with LVAD patients are infrequent but have high rates of admission and incidence of life-threatening diagnoses. The most common prehospital presenting symptoms were weakness and chest pain, and most prehospital interactions did not require LVAD-specific interventions. In addition to acquiring technical knowledge regarding LVADs, EMS providers should be aware of non-device-related complications including intracranial and GI bleeding and take this into account during their assessment.

Antiarrhythmic Drugs for Nonshockable-Turned-Shockable Out-of-Hospital Cardiac Arrest: The ALPS Study (Amiodarone, Lidocaine, or Placebo).

BACKGROUND: Out-of-hospital cardiac arrest (OHCA) commonly presents with nonshockable rhythms (asystole and pulseless electric activity). It is unknown whether antiarrhythmic drugs are safe and effective when nonshockable rhythms evolve to shockable rhythms (ventricular fibrillation/pulseless ventricular tachycardia [VF/VT]) during resuscitation. METHODS: Adults with nontraumatic OHCA, vascular access, and VF/VT anytime after ≥1 shock(s) were prospectively randomized, double-blind, to receive amiodarone, lidocaine, or placebo by paramedics. Patients presenting with initial shock-refractory VF/VT were previously reported. The current study was a prespecified analysis in a separate cohort that initially presented with nonshockable OHCA and was randomized on subsequently developing shock-refractory VF/VT. The primary outcome was survival to hospital discharge. Secondary outcomes included discharge functional status and adverse drug-related effects. RESULTS: Of 37 889 patients with OHCA, 3026 with initial VF/VT and 1063 with initial nonshockable-turned-shockable rhythms were treatment-eligible, were randomized, and received their assigned drug. Baseline characteristics among patients with nonshockable-turned-shockable rhythms were balanced across treatment arms, except that recipients of a placebo included fewer men and were less likely to receive bystander cardiopulmonary resuscitation. Active-drug recipients in this cohort required fewer shocks, supplemental doses of their assigned drug, and ancillary antiarrhythmic drugs than recipients of a placebo (P<0.05). In all, 16 (4.1%) amiodarone, 11 (3.1%) lidocaine, and 6 (1.9%) placebo-treated patients survived to hospital discharge (P=0.24). No significant interaction between treatment assignment and discharge survival occurred with the initiating OHCA rhythm (asystole, pulseless electric activity, or VF/VT). Survival in each of these categories was consistently higher with active drugs, although the trends were not statistically significant. Adjusted absolute differences (95% confidence interval) in survival from nonshockable-turned-shockable arrhythmias with amiodarone versus placebo were 2.3% (-0.3, 4.8), P=0.08, and for lidocaine versus placebo 1.2% (-1.1, 3.6), P=0.30. More than 50% of these survivors were functionally independent or required minimal assistance. Drug-related adverse effects were infrequent. CONCLUSIONS: Outcome from nonshockable-turned-shockable OHCA is poor but not invariably fatal. Although not statistically significant, point estimates for survival were greater after amiodarone or lidocaine than placebo, without increased risk of adverse effects or disability and consistent with previously observed favorable trends from treatment of initial shock-refractory VF/VT with these drugs. Together the findings may signal a clinical benefit that invites further investigation. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT01401647.

Preliminary report of a mathematical model of ventilation and intrathoracic pressure applied to prehospital patients with severe traumatic brain injury.

BACKGROUND: Inadvertent hyperventilation is associated with poor outcomes from traumatic brain injury (TBI). Hypocapnic cerebral vasoconstriction is well described and causes an immediate and profound decrease in cerebral perfusion. The hemodynamic effects of positive-pressure ventilation (PPV) remain incompletely understood but may be equally important, particularly in the hypovolemic patient with TBI. OBJECTIVE: Preliminary report on the application of a previously described mathematical model of perfusion and ventilation to prehospital data to predict intrathoracic pressure. METHODS: Ventilation data from 108 TBI patients (76 ground transported, 32 helicopter transported) were used for this analysis. Ventilation rate (VR) and end-tidal carbon dioxide (PetCO2) values were used to estimate tidal volume (VT). The values for VR and estimated VT were then applied to a previously described mathematical model of perfusion and ventilation. This model allows input of various lung parameters to define a pressure-volume relationship, then derives mean intrathoracic pressure (MITP) for various VT and VR values. For this analysis, normal lung parameters were utilized. Separate analyses were performed assuming either fixed or variable PaCO2-PetCO2 differences. Ground and air medical patients were compared with regard to VR, PetCO2, estimated VT, and predicted MITP. RESULTS: A total of 10,647 measurements were included from the 108 TBI patients, representing about 13 minutes of ventilation per patient. Mean VR values were higher for ground patients versus air patients (21.6 vs. 19.7 breaths/min; p < 0.01). Estimated VT values were similar for ground and air patients (399 mL vs. 392 mL; p = NS) in the fixed model but not the variable (636 vs. 688 mL, respectively; p < 0.01). Mean PetCO2 values were lower for ground versus air patients (30.6 vs. 33.8 mmHg; p < 0.01). Predicted MITP values were higher for ground versus air patients, assuming either fixed (9.0 vs. 8.1 mmHg; p < 0.01) or variable (10.9 vs. 9.7 mmHg; p < 0.01) PaCO2-PetCO2 differences. CONCLUSIONS: Predicted MITP values increased with ventilation rates. Future studies to externally validate this model are warranted.

A retrospective review of the prehospital use of activated charcoal.

OBJECTIVE: We studied the complications and timing implications of prehospital activated charcoal (PAC). Appropriateness of PAC administration was also evaluated. METHODS: We retrospectively reviewed prehospital records over 32 months for overdose cases, where PAC was administered. Cases were assessed for amount and type of ingestant, clinical findings, timing of PAC, timing of transport and arrival into the emergency department (ED), and complications. Encounter duration in cases of PAC was compared with that, for all cases during the study period, where an overdose patient who did not receive activated charcoal was transported. RESULTS: Two thousand eight hundred forty-five total cases were identified. In 441 cases, PAC was given; and complications could be assessed. Two hundred eighty-one of these had complete information regarding timing of ingestion, activated charcoal administration, and transport. The average time between overdose and PAC was 49.8 minutes (range, 7-199 minutes; median, 41.0 minutes; SD, 30.4 minutes). Complications included emesis (7%), declining mental status (4%), declining blood pressure (0.4%), and declining oxygen saturation (0.4%). Four hundred seventeen cases of PAC had documentation of timing of emergency medical service (EMS) arrival on scene and arrival at the ED. Average EMS encounter time was 29 minutes (range, 10-53 minutes; median, 27.9 minutes). Two thousand forty-four poisoning patients were transported who did not receive PAC. The average EMS encounter time for this group was 28.1 minutes (range, 4-82 minutes; median, 27.3 minutes), not significantly different (P =.114). CONCLUSIONS: Prehospital activated charcoal did not appear to markedly delay transport or arrival of overdose patients into the ED and was generally safe.

A trial of an impedance threshold device in out-of-hospital cardiac arrest.

BACKGROUND: The impedance threshold device (ITD) is designed to enhance venous return and cardiac output during cardiopulmonary resuscitation (CPR) by increasing the degree of negative intrathoracic pressure. Previous studies have suggested that the use of an ITD during CPR may improve survival rates after cardiac arrest. METHODS: We compared the use of an active ITD with that of a sham ITD in patients with out-of-hospital cardiac arrest who underwent standard CPR at 10 sites in the United States and Canada. Patients, investigators, study coordinators, and all care providers were unaware of the treatment assignments. The primary outcome was survival to hospital discharge with satisfactory function (i.e., a score of ≤3 on the modified Rankin scale, which ranges from 0 to 6, with higher scores indicating greater disability). RESULTS: Of 8718 patients included in the analysis, 4345 were randomly assigned to treatment with a sham ITD and 4373 to treatment with an active device. A total of 260 patients (6.0%) in the sham-ITD group and 254 patients (5.8%) in the active-ITD group met the primary outcome (risk difference adjusted for sequential monitoring, -0.1 percentage points; 95% confidence interval, -1.1 to 0.8; P=0.71). There were also no significant differences in the secondary outcomes, including rates of return of spontaneous circulation on arrival at the emergency department, survival to hospital admission, and survival to hospital discharge. CONCLUSIONS: Use of the ITD did not significantly improve survival with satisfactory function among patients with out-of-hospital cardiac arrest receiving standard CPR. (Funded by the National Heart, Lung, and Blood Institute and others; ROC PRIMED ClinicalTrials.gov number, NCT00394706.).

Prehospital stroke diagnosis and treatment in ambulances and helicopters-a concept paper.

Stroke is the second common cause of death and the primary cause of early invalidity worldwide. Different from other diseases is the time sensitivity related to stroke. In case of an ischemic event occluding a brain artery, 2000000 neurons die every minute. Stroke diagnosis and treatment should be initiated at the earliest time point possible, preferably at the site or during patient transport. Portable ultrasound has been used for prehospital diagnosis for applications other than stroke, and its acceptance as a valuable diagnostic tool "in the field" is growing. The intrahospital use of transcranial ultrasound for stroke diagnosis has been described extensively in the literature. Beyond its diagnostic use, first clinical trials as well as numerous preclinical work demonstrate that ultrasound can be used to accelerate clot lysis (sonothrombolysis) in presence as well as in absence of tissue plasminogen activator. Hence, the use of transcranial ultrasound for diagnosis and possibly treatment of stroke bares the potential to add to current stroke care paradigms significantly. The purpose of this concept article is to describe the opportunities presented by recent advances in transcranial ultrasound to diagnose and potentially treat large vessel embolic stroke in the prehospital environment.

Assessment of the addition of prehospital continuous positive airway pressure (CPAP) to an urban emergency medical services (EMS) system in persons with severe respiratory distress.

BACKGROUND: The use of continuous positive airway pressure (CPAP) assisted ventilation in the emergency department(ED) has been well described. OBJECTIVES: The purpose of this study was to measure the efficacy of adding pre-hospital CPAP to an urban emergency medical service (EMS) respiratory distress protocol on persons with respiratory distress. METHODS: A historical cohort analysis of consecutive patients between 2005 and 2010. Groups were matched for severity of respiratory distress. Physiologic variables were the primary outcome obtained from first responders and upon triage in the ED. Additional outcomes included endotracheal intubation rate, hospital mortality, overall hospital length of stay(LOS), intensive care unit (ICU) admission, and ICU length of stay (ICU LOS). RESULTS: There were 410 consecutive patients with predetermined criteria for severe respiratory distress, 235 historical controls matched with 175 post-implementation patients. Average age was 67 years, 54% being male. There were significant median differences in heart and respiratory rates favoring the historical cohort (p < 0.05). There were no significant differences in intubation rate, overall hospital LOS, ICU admission rate, ICU LOS, and hospital mortality (p > 0.05).Patients that were continued on noninvasive ventilatory assistance had a significantly improved rate of intubation and ICU LOS (p < 0.05). CONCLUSIONS: The addition of CPAP to our pre-hospital respiratory distress protocol did not improve physiologic variables.There were no differences in overall and ICU LOS between groups. Persons with apparent continued ventilatory assistance appeared to have improved rates of intubation and ICU LOS [corrected].

Effects of an emergency medical services-based resource access program on frequent users of health services.

BACKGROUND: A small group of adults disproportionately and ineffectively use acute services including emergency medical services (EMS) and emergency departments (EDs). The resulting episodic, uncoordinated care is of lower quality and higher cost and simultaneously consumes valuable public safety and acute care resources. OBJECTIVE: To address this issue, we measured the impact of a pilot, EMS-based case management and referral intervention termed the San Diego Resource Access Program (RAP) to reduce EMS, ED, and inpatient (IP) visits. METHODS: This was a historical cohort study of RAP records and billing data of EMS and one urban hospital for 51 individuals sequentially enrolled in the program. The study sample consisted of adults with ≥ 10 EMS transports within 12 months and others reported by prehospital personnel with significant recent increases in transports. Data were collected over a 31-month time period from December 2006 to June 2009. Data were collected for equal pre- and postenrollment time periods based on date of initial RAP contact, and comparisons were made using the Wilcoxon signed-rank test. Overall use for subjects is reported. RESULTS: The majority of subjects were male (64.7%), homeless (58.8%), and 40 to 59 years of age (72.5%). Between the pre and post periods, EMS encounters declined 37.6% from 736 to 459 (p = 0.001), resulting in a 32.1% decrease in EMS charges from $689,743 to $468,394 (p = 0.004). The EMS task time and mileage decreased by 39.8% and 47.5%, respectively, accounting for 262 (p = 0.008) hours and 1,940 (p = 0.006) miles. The number of ED encounters at the one participating hospital declined 28.1% from 199 to 143, which correlated with a 12.7% decrease in charges from $413,410 to $360,779. The number of IP admissions declined by 9.1% from 33 to 30, corresponding to a 5.9% decrease in IP charges from $687,306 to $646,881. Hospital length of stay declined 27.9%, from 122 to 88 days. Across all services, total charges declined by $314,406. CONCLUSIONS: This pilot study demonstrated that an EMS-based case management and referral program was an effective means of decreasing EMS transports by frequent users, but had only a limited impact on use of hospital services.

Gender differences in scene time, transport time, and total scene to hospital arrival time determined by the use of a prehospital electrocardiogram in patients with complaint of chest pain.

BACKGROUND: Recent studies have described a gender bias against women in the setting of acute coronary syndrome (ACS). OBJECTIVES: We sought to measure the impact that a prehospital electrocardiogram (PH ECG) has on prehospital total scene time to hospital arrival time, comparing men and women with the complaint of chest pain (cCP). METHODS: This study retrospectively analyzed San Diego Emergency Medical Services (EMS) runsheets of patients with cCP before and after implementation of the PH ECG protocol. The average scene time (ST), transport time (TT), and total scene-to-arrival-at-hospital time (STH) were compared. After stratification by gender, times were compared in patients with ST-elevation myocardial infarction (STEMI) to those without STEMI. RESULTS: Of 21,742 EMS activations for patients with cCP, there were no significant differences overall. When stratified by gender, there was a significant reduction of ST (00:19:16 min vs. 00:20:48 min, p<0.001, 95% CI 00:01:17-00:01:48) and STH (00:33:22 min vs. 00:35:44 min, p<0.001, 95% CI 00:01:21-00:02:24) favoring men in cases without STEMI. In cases of STEMI, men had a significant reduction in ST (00:17:27 min vs. 00:20:29 min, p<0.001, 95% CI 00:01:24-00:04:40) and STH (00:30:30 min vs. 00:34:25 min, p<0.01, 95% CI 00:01:23-00:06:26) times compared to women. CONCLUSION: Prehospital ECG implementation led to no significant differences in pre- and post-implementation times. In cases of STEMI, men had significantly reduced scene time and scene-to-hospital time when compared to women. The precise reason for these disparities remains unknown.

An open, interoperable, and scalable prehospital information technology network architecture.

Some of the most intractable challenges in prehospital medicine include response time optimization, inefficiencies at the emergency medical services (EMS)-emergency department (ED) interface, and the ability to correlate field interventions with patient outcomes. Information technology (IT) can address these and other concerns by ensuring that system and patient information is received when and where it is needed, is fully integrated with prior and subsequent patient information, and is securely archived. Some EMS agencies have begun adopting information technologies, such as wireless transmission of 12-lead electrocardiograms, but few agencies have developed a comprehensive plan for management of their prehospital information and integration with other electronic medical records. This perspective article highlights the challenges and limitations of integrating IT elements without a strategic plan, and proposes an open, interoperable, and scalable prehospital information technology (PHIT) architecture. The two core components of this PHIT architecture are 1) routers with broadband network connectivity to share data between ambulance devices and EMS system information services and 2) an electronic patient care report to organize and archive all electronic prehospital data. To successfully implement this comprehensive PHIT architecture, data and technology requirements must be based on best available evidence, and the system must adhere to health data standards as well as privacy and security regulations. Recent federal legislation prioritizing health information technology may position federal agencies to help design and fund PHIT architectures.

Asphyxiation due to dry ice in a walk-in freezer.

BACKGROUND: Exposure to a high concentration of environmental carbon dioxide (CO2) can result in poisoning through direct toxicity and by displacing atmospheric oxygen (O2). Dry ice undergoes sublimation to a gaseous state at -78.5 degrees C (-109.3 degrees F), which is heavier than air and can accumulate in dependent areas. CASE REPORT: We report the case of a 59-year-old man found in cardiac arrest shortly after entering a recently repaired walk-in freezer that contained dry ice. First responders and bystanders did not recognize the proximate hazardous environment but were fortunately uninjured. A careful Emergency Department history coupled with rapid case investigation by the Medical Examiner's Office led to the determination of the cause of death and the elimination of the ongoing hazard. CONCLUSION: This case illustrates the lethal consequences of improper storage of dry ice and the need to consider toxic environmental exposure as a cause of sudden cardiac arrest.

Prehospital transport time intervals for acute stroke patients.

BACKGROUND: Recognizing factors that cause prehospital stroke delays may improve time of presentation to the Emergency Department (ED) and allow earlier treatment of acute stroke patients. STUDY OBJECTIVES: To determine the impact of stroke recognition by emergency medical dispatchers (EMD) and paramedics (PM) on ED arrival time in a large urban Emergency Medical Services system. METHODS: Retrospective study of patients aged 18 years or more identified as having acute stroke by EMD, PM, or stroke neurologists from January 1, 2005 to December 31, 2005. Data were acquired from computer-assisted dispatch records, paramedic assessments, ICD-9 (International Classification of Diseases, 9(th) Revision) databases, and a hospital stroke registry. Paramedic time to scene, scene time, and total run time were computed for patients with final hospital diagnosis of stroke and grouped into missed strokes and identified strokes by EMD and PM. Time intervals were compared between missed and identified strokes as well as between incidents where EMD and PM agreed or disagreed. RESULTS: A total of 1067 patients were eligible for the study; 22 were excluded for missing data. For true strokes, EMD and PM were in agreement 27.3% of the time. The median RT was 2.5 min shorter when there was agreement between the providers than when there was disagreement (36.5 min; interquartile range [IQR] 30-43 vs. 39 min.; IQR 33-45, respectively). CONCLUSIONS: Prehospital scene time and run times for acute strokes are less when there is diagnostic concordance between dispatchers and paramedics. Time intervals did not differ between missed and recognized strokes.

Effect of prehospital 12-lead electrocardiogram on activation of the cardiac catheterization laboratory and door-to-balloon time in ST-segment elevation acute myocardial infarction.

Reducing door-to-balloon (D + B) time during primary percutaneous coronary intervention for patients with ST-segment elevation myocardial infarction (STEMI) reduces mortality. Prehospital 12-lead electrocadiography (ECG) with cardiac catheterization laboratory (CCL) activation may reduce D + B time. Paramedic-performed ECG was initiated in the city of San Diego in January 2005 with STEMI diagnosis based on an automated computer algorithm. We undertook this study to determine the effect of prehospital CCL activation on D + B time for patients with acute STEMI brought to our institution. All data were prospectively collected for patients with STEMI including times to treatment and clinical outcomes. We evaluated 78 consecutive patients with STEMI from January 2005 to June 2006, and the study group consisted of all patients with prehospital activation of the CCL (field STEMI; n = 20). The control groups included concurrently-treated patients with STEMI during the same period who presented to the emergency department (nonfield STEMI; n = 28), and all patients with STEMI treated in the preceding year (2004) (historical STEMI; n = 30). Prehospital CCL activation significantly reduced D + B time (73 +/- 19 minutes field STEMI, 130 +/- 66 minutes nonfield STEMI, 141 +/- 49 minutes historical STEMI; p <0.001) with significant reductions in door-to-CCL and CCL-to-balloon times as well. The majority of patients with field STEMI achieved D + B times of <90 minutes (80% field STEMI, 25% nonfield STEMI, 10% historical STEMI; p <0.001). In conclusion, this study demonstrates that prehospital electrocardiographic diagnosis of STEMI with activation of the CCL markedly reduces D + B time.

Rate of decline in oxygen saturation at various pulse oximetry values with prehospital rapid sequence intubation.

BACKGROUND: A high incidence of desaturations has been observed during prehospital rapid sequence intubation (RSI). The rate of decline in oxygen saturation (SpO2) at various pulse oximetry values has not been defined with emergency RSI. Objective. To define the rate of SpO2 decline at various pulse oximetry values and identify a threshold below which active BVM should be performed during prehospital RSI. METHODS: Traumatic brain injury (TBI) patients undergoing RSI by prehospital providers were included in this analysis. The time period from the highest to the lowest preintubation SpO2 value was selected for review. The mean rate of SpO2 decline was calculated for each SpO2 value and then used to define a theoretical SpO2 desaturation curve. The rate of desaturation to hypoxemia (SpO2

Serum troponin I measurement of subjects exposed to the Taser X-26.

The Taser is a high-voltage, low-amperage conducted energy device used by many law enforcement agencies as a less lethal force weapon. The objective of this study was to evaluate for a rise in serum troponin I level after deployment of the Taser on law enforcement training volunteers. A prospective, observational cohort study was performed evaluating serum troponin I levels in human subjects 6 h after an exposure to the Taser X-26. Outcome measures included abnormal elevation in serum troponin I level (> 0.2 ng/mL). There were 66 subjects evaluated. The mean shock duration was 4.36 s (range 1.2-5 s). None of the subjects had a positive troponin I level 6 h after exposure. It was concluded that human volunteers exposed to a single shock from the Taser did not develop an abnormal serum troponin I level 6 h after shock, suggesting that there was no myocardial necrosis or infarction.

Hyperventilation following aero-medical rapid sequence intubation may be a deliberate response to hypoxemia.

BACKGROUND: Recent studies document a high incidence of hyperventilation by prehospital providers, with a potentially detrimental effect on outcome in traumatic brain injury (TBI). PURPOSE: To document the incidence of hyperventilation by aero-medical providers and explore a possible relationship between hyperventilation episodes and desaturations or impending hypoxemia. METHODS: This was a prospective, descriptive study using TBI patients undergoing prehospital RSI by aero-medical crews. Continuous data regarding end-tidal CO2 (EtCO2), ventilatory rate, and oxygen saturation (SpO2) were downloaded from hand-held oximeter-capnometer devices. Two investigators independently assessed oximetry/capnometry data to identify the following occurrences: desaturation during RSI (SpO2 < 90%), impending hypoxemia (SpO2 decrease by >or=3% to a value <95%) following intubation, loss of SpO2 signal, hyperventilation (EtCO2<30 mm Hg), and severe hyperventilation (EtCO2 < 25 mm Hg). Covariate analysis was used to explore the possible association between hyperventilation episodes and either desaturation, impending hypoxemia, or loss of SpO2 signal. RESULTS: A total of 32 aero-medical patients were enrolled with a mean duration of ventilation monitoring of 14.8 min. The incidence of hyperventilation or severe hyperventilation was substantially lower than previously documented with ground paramedics. A total of 28 hyperventilation episodes were identified in 16 patients; 13 of these were associated with impending hypoxemia following intubation, five were associated with desaturation during RSI, and seven were associated with loss of SpO2 signal. The remaining three occurred immediately following intubation without desaturation during RSI. Desaturation was observed in 62% of patients; of note, desaturation was recorded on the quality improvement document in only 23% of these. Covariate analysis revealed an association between hyperventilation episodes and either desaturatios during RSI, impending hypoxemia following intubation, or loss of SpO2 signal. CONCLUSIONS: The incidence of hyperventilation by aeromedical crews was lower than reported for ground paramedics and appears to occur in response to desaturation, impending hypoxemia, or loss of SpO2 signal.

The feasibility of a regional cardiac arrest receiving system.

BACKGROUND: Patients suffering out-of-hospital cardiac arrest (OOHCA) are generally transported to the closest ED, presumably to expedite a hospital level of care and improve the chances of return for spontaneous circulation (ROSC) or provide post-resuscitative care for patients with prehospital ROSC. As hospital-based therapies for survivors of OOHCA are identified, such as hypothermia and emergency primary coronary interventions (PCI), certain hospitals may be designated as cardiac arrest receiving facilities. The safety of bypassing non-designated facilities with such a regional system is not known. OBJECTIVES: To explore the potential ED contribution in OOHCA victims without prehospital ROSC and document the relationship between transport time and outcome in patients with prehospital ROSC. METHODS: This was a prospective, observational study conducted in a large, urban EMS system over an 18-month period. Data were collected using the Utstein template for OOHCA. The incidence of prehospital ROSC was calculated for patients who were declared dead on scene, transported but died in the ED, died in the hospital, and survived to hospital discharge. The relationship between transport time and survival was also explored for patients with prehospital ROSC. RESULTS: A total of 1141 cardiac arrest patients were enrolled over the 18-month period. A strong association between prehospital ROSC and final disposition was observed (chi-square test for trend p<0.001). Only two patients who survived to hospital discharge did not have prehospital ROSC. Mean transport times were not significantly different for patients with prehospital ROSC who were declared dead in the ED (8.3min), died following hospital admission (7.8min), and survived to hospital discharge (8.5min). Outcomes in patients with prehospital ROSC who had shorter (7min or less) versus longer transport times were similar, and receiver-operator curve analysis indicated no predictive ability of transport time with regard to survival to hospital admission (area under the curve=0.52). CONCLUSIONS: In this primarily urban EMS system, the vast majority of survivors from OOHCA are resuscitated in the field. A relationship between transport time and survival to hospital admission or discharge was not observed. This supports the feasibility of developing a regional cardiac arrest system with designated receiving facilities.

Cardiac monitoring of human subjects exposed to the taser.

The Taser (TASER International, Scottsdale, AZ) is a high-voltage, low-amperage device used by many law enforcement agencies. Our objective in this study was to evaluate for rhythm changes utilizing cardiac monitoring during deployment of the Taser on volunteers. A prospective, observational study evaluated law enforcement personnel who had continuous electrocardiographic monitoring immediately before, during, and after having a voluntary exposure to the Taser X-26. Changes in cardiac rate, rhythm, ectopy, morphology, and conduction intervals were measured. A total of 105 subjects were evaluated. The mean shock duration was 3.0 s (range 0.9-5 s). Mean heart rate increased 15 beats/min (95% CI 12.6-18.3), from 122 beats/min before shock to 137 beats/min immediately after shock. One subject had a single premature ventricular contraction both before and after the shock, but no other subject developed ectopy or dysrhythmia. Poor inter-rater agreement prevented determination of the overall effect of shock on conduction intervals. However, several interpretable tracings demonstrated change in QT duration-either shortening or prolongation after shock. Human subjects exposed to a brief shock from the Taser developed significant increases in heart rate, but there were no cardiac dysrhythmias or morphologic changes. Alterations in the QT interval were observed in some subjects but their true incidence and clinical significance are unknown.