David Hostler

Chest Compression Fraction Determines Survival in Patients With Out-of-Hospital Ventricular Fibrillation

Background— Quality cardiopulmonary resuscitation contributes to cardiac arrest survival. The proportion of time in which chest compressions are performed in each minute of cardiopulmonary resuscitation is an important modifiable aspect of quality cardiopulmonary resuscitation. We sought to estimate the effect of an increasing proportion of time spent performing chest compressions during cardiac arrest on survival to hospital discharge in patients with out-of-hospital ventricular fibrillation or pulseless ventricular tachycardia. Methods and Results— This is a prospective observational cohort study of adult patients from the Resuscitation Outcomes Consortium Cardiac Arrest Epistry with confirmed ventricular fibrillation or ventricular tachycardia, no defibrillation before emergency medical services arrival, electronically recorded cardiopulmonary resuscitation before the first shock, and a confirmed outcome. Patients were followed up to discharge from the hospital or death. Of the 506 cases, the mean age was 64 years, 80% were male, 71% were witnessed by a bystander, 51% received bystander cardiopulmonary resuscitation, 34% occurred in a public location, and 23% survived. After adjustment for age, gender, location, bystander cardiopulmonary resuscitation, bystander witness status, and response time, the odds ratios of surviving to hospital discharge in the 2 highest categories of chest compression fraction compared with the reference category were 3.01 (95% confidence interval 1.37 to 6.58) and 2.33 (95% confidence interval 0.96 to 5.63). The estimated adjusted linear effect on odds ratio of survival for a 10% change in chest compression fraction was 1.11 (95% confidence interval 1.01 to 1.21). Conclusions— An increased chest compression fraction is independently predictive of better survival in patients who experience a prehospital ventricular fibrillation/tachycardia cardiac arrest.

Early versus Later Rhythm Analysis in Patients with Out-of-Hospital Cardiac Arrest

BACKGROUND In a departure from the previous strategy of immediate defibrillation, the 2005 resuscitation guidelines from the American Heart Association-International Liaison Committee on Resuscitation suggested that emergency medical service (EMS) personnel could provide 2 minutes of cardiopulmonary resuscitation (CPR) before the first analysis of cardiac rhythm. We compared the strategy of a brief period of CPR with early analysis of rhythm with the strategy of a longer period of CPR with delayed analysis of rhythm. METHODS We conducted a cluster-randomized trial involving adults with out-of-hospital cardiac arrest at 10 Resuscitation Outcomes Consortium sites in the United States and Canada. Patients in the early-analysis group were assigned to receive 30 to 60 seconds of EMS-administered CPR and those in the later-analysis group were assigned to receive 180 seconds of CPR, before the initial electrocardiographic analysis. The primary outcome was survival to hospital discharge with satisfactory functional status (a modified Rankin scale score of ≤3, on a scale of 0 to 6, with higher scores indicating greater disability). RESULTS We included 9933 patients, of whom 5290 were assigned to early analysis of cardiac rhythm and 4643 to later analysis. A total of 273 patients (5.9%) in the later-analysis group and 310 patients (5.9%) in the early-analysis group met the criteria for the primary outcome, with a cluster-adjusted difference of -0.2 percentage points (95% confidence interval, -1.1 to 0.7; P=0.59). Analyses of the data with adjustment for confounding factors, as well as subgroup analyses, also showed no survival benefit for either study group. CONCLUSIONS Among patients who had an out-of-hospital cardiac arrest, we found no difference in the outcomes with a brief period, as compared with a longer period, of EMS-administered CPR before the first analysis of cardiac rhythm. (Funded by the National Heart, Lung, and Blood Institute and others; ROC PRIMED ClinicalTrials.gov number, NCT00394706.).

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.).

Defining the Learning Curve for Paramedic Student Endotracheal Intubation

Background. Proficiency in endotracheal intubation (ETI) is assumed to improve primarily with accumulated experience on live patients. While the National Standard Paramedic Curriculum recommends that paramedic students (PSs) perform at least five live ETIs, these training opportunities are limited. Objective. To evaluate the effects of cumulative live ETI experience, elapsed duration of training, andclinical setting on PS ETI proficiency. Methods. The authors used longitudinal, multicenter data from 60 paramedic training programs over a two-year period. The PSs reported outcomes (success/failure) for all live ETIs attempted in the operating room (OR), the emergency department (ED), the intensive care unit (ICU), andother hospital or prehospital settings. Fixed-effects logistic regression was used to model up to 30 consecutive ETI efforts by each PS, accounting for per-PS clustering. For each patient, the authors evaluated the association between ETI success andthe PSs cumulative number of ETIs, adjusted for clinical setting, elapsed number of days from the first ETI encounter, andthe interaction (cumulative ETIs × elapsed days). Predicted probability plots were constructed depicting the “learning curve” overall andfor each clinical setting. Results. Between one and74 ETIs (median 7; IQR 4–12) were performed by each of 802 PSs. Of 7,635 ETIs, 6,464 (87.4%) were successful. Stratified by clinical setting, 6,311 (82.7%) ETIs were performed in the OR, 271 (3.6%) in the ED, 64 (0.8%) in the ICU, 86 (1.1%) in other in-hospital settings, and903 (11.8%) in the prehospital setting. For the 7,398 ETIs included in the multivariate analysis, cumulative number of ETI was associated with increased adjusted odds of ETI success (odds ratio 1.067 per ETI; 95% CI: 1.044–1.091). ETI learning curves were steepest for the ICU andprehospital settings but lower than for other clinical settings. Conclusions. Paramedic student ETI success improves with accumulated live experience but appears to vary across different clinical settings. Strategies for PS airway education must consider the volume of live ETIs as well as the clinical settings used for ETI training. Key words: intubation; intratracheal; emergency medical services; learning; allied health personnel.

Effect of real-time feedback during cardiopulmonary resuscitation outside hospital: prospective, cluster-randomised trial

Objective To investigate whether real-time audio and visual feedback during cardiopulmonary resuscitation outside hospital increases the proportion of subjects who achieved prehospital return of spontaneous circulation. Design A cluster-randomised trial. Subjects 1586 people having cardiac arrest outside hospital in whom resuscitation was attempted by emergency medical services (771 procedures without feedback, 815 with feedback). Setting Emergency medical services from three sites within the Resuscitation Outcomes Consortium in the United States and Canada. Intervention Real-time audio and visual feedback on cardiopulmonary resuscitation (CPR) provided by the monitor-defibrillator. Main outcome measure Prehospital return of spontaneous circulation after CPR. Results Baseline patient and emergency medical service characteristics did not differ between groups. Emergency medical services muted the audible feedback in 14% of cases during the period with feedback. Compared with CPR clusters lacking feedback, clusters assigned to feedback were associated with increased proportion of time in which chest compressions were provided (64% v 66%, cluster-adjusted difference 1.9 (95% CI 0.4 to 3.4)), increased compression depth (38 v 40 mm, adjusted difference 1.6 (0.5 to 2.7)), and decreased proportion of compressions with incomplete release (15% v 10%, adjusted difference −3.4 (−5.2 to −1.5)). However, frequency of prehospital return of spontaneous circulation did not differ according to feedback status (45% v 44%, adjusted difference 0.1% (−4.4% to 4.6%)), nor did the presence of a pulse at hospital arrival (32% v 32%, adjusted difference −0.8 (−4.9 to 3.4)), survival to discharge (12% v 11%, adjusted difference −1.5 (−3.9 to 0.9)), or awake at hospital discharge (10% v 10%, adjusted difference −0.2 (−2.5 to 2.1)). Conclusions Real-time visual and audible feedback during CPR altered performance to more closely conform with guidelines. However, these changes in CPR performance were not associated with improvements in return of spontaneous circulation or other clinical outcomes. Trial Registration Clinical Trials NCT00539539

A descriptive analysis of emergency medical service systems participating in the Resuscitation Outcomes Consortium (ROC) network

Background. The optimal Emergency Medical Services (EMS) system characteristics have not been defined, resulting in substantial variability across systems. The Resuscitation Outcomes Consortium (ROC) is a United States-Canada research network that organized EMS agencies from 11 different systems to perform controlled trials in cardiac arrest andlife-threatening trauma resuscitation. Objectives. To describe EMS systems participating in ROC using a novel framework. Methods. Standardized surveys were created by ROC investigators anddistributed to each site for completion. These included separate questions for individual hospitals, EMS agencies, anddispatch centers. Results were collated andanalyzed by using descriptive statistics. Results. A total of 264 EMS agencies, 287 hospitals, and154 dispatch centers were included. Agencies were described with respect to the type (fire-based, non-fire governmental, private), transport status (transport/non-transport), andtraining level (BLS/ALS). Hospitals were described with regard to their trauma designation andthe presence of electrophysiology andcardiac catheterization laboratories. Dispatch center characteristics, including primary versus secondary public safety answering point (PSAP) status andthe use of prearrival instructions, were also described. Differences in EMS system characteristics between ROC sites were observed with multiple intriguing patterns. Rural areas andfire-based agencies had more EMS units andproviders per capita. This may reflect longer response andtransport distances in rural areas andthe additional duties of most fire-based providers. In addition, hospitals in the United States typically had catheterization laboratories, whereas Canadian hospitals generally did not. The vast majority of both primary andsecondary PSAPs use computer-aided dispatch. Conclusions. Similarities anddifferences among EMS systems participating in the ROC network were described. The framework used in this analysis may serve as a template for future EMS research.

Procedural experience with out-of-hospital endotracheal intubation.

Objective:Out-of-hospital rescuers likely need regular clinical experience to perform endotracheal intubation (ETI) in a safe and effective manner. We sought to determine the frequency of ETI performed by individual out-of-hospital rescuers. Design:Analysis of an administrative database of all emergency medical services (EMS) patient care reports in Pennsylvania. Setting:Commonwealth of Pennsylvania from January 1 to December 31, 2003. Subjects:EMS advanced life support rescuers (paramedics, prehospital nurses, and EMS physicians) who reported at least one patient contact during the study period. Interventions:None. Measurements:We calculated individual rescuer ETI frequency and opportunity. We evaluated relationships between ETI frequency and the number of patient contacts. We also examined the relationship with practice setting (air medical vs. ground rescuers and urban vs. rural rescuers). Main Results:In 1,544,791 patient care reports, 11,484 ETIs were reported by 5,245 out-of-hospital rescuers. The median ETI frequency was one (interquartile range, 0–3; range, 0–23). Of 5,245 rescuers, >67% (3,551) performed two or fewer ETIs, and >39% (2,054) rescuers did not perform any ETIs. The median number of ETI opportunities was three (interquartile range, 0–6; range, 0–76). ETI frequency was associated with patient volume (Spearman’s &rgr; = 0.67) and was higher for air medical (p = .006) and urban (p < .0001) rescuers. ETI frequency was not associated with response (Spearman’s &rgr; = −0.01) or transport (Spearman’s &rgr; = −0.06) times. Conclusions:Out-of-hospital ETI, an important and difficult resuscitation intervention, is an uncommon event for most rescuers.

Ventricular fibrillation scaling exponent can guide timing of defibrillation and other therapies.

Background—The scaling exponent (ScE) of the ventricular fibrillation (VF) waveform correlates with duration of VF and predicts defibrillation outcome. We compared 4 therapeutic approaches to the treatment of VF of various durations. Methods and Results—Seventy-two swine (19.5 to 25.7 kg) were randomly assigned to 1 of 9 groups (n=8 each). VF was induced and left untreated until the ScE reached 1.10, 1.20, 1.30, or 1.40. Animals were treated with either immediate countershock (IC); 3 minutes of CPR before the first countershock (CPR); CPR for 2 minutes, then drugs given with 3 more minutes of CPR before the first shock (CPR-D); or drugs given at the start of CPR with 3 minutes of CPR before the first shock (Drugs+CPR). Return of spontaneous circulation (ROSC) and 1-hour survival were analyzed with &khgr;2 and Kaplan-Meier survival curves. IC was effective when the ScE was low but had decreasing success as the ScE increased. No animals in the 1.30 or 1.40 groups had ROSC from IC (0 of 16). CPR did not improve first shock outcome in the 1.20 CPR group (3 of 8 ROSC). Kaplan-Meier survival analyses indicated that IC significantly delayed time to ROSC in both the 1.3 (P =0.0006) and the 1.4 (P =0.005) groups. Conclusions—VF of brief to moderate duration is effectively treated by IC. When VF is prolonged, as indicated by an ScE of 1.3 or greater, IC was not effective and delayed time to ROSC. The ScE can help in choosing the first intervention in the treatment of VF.

The Public Access Defibrillation (PAD) trial: study design and rationale.

The PAD Trial is a prospective, multicenter, randomized clinical study testing whether volunteer, non-medical responders can improve survival from out-of-hospital cardiac arrest (OOH-CA) by using automated external defibrillators (AEDs). These lay volunteers, who have no traditional responsibility to respond to a medical emergency as part of their primary job description, will form part of a comprehensive, integrated community approach to the treatment of OOH-CA. The study is being conducted at 24 field centers in the United States and Canada. Approximately 1000 community units (e.g. apartment or office buildings, gated communities, sports facilities, senior centers, shopping malls, etc.) were randomized to treatment by trained laypersons who will provide either cardiopulmonary resuscitation (CPR) alone or CPR plus use of an AED, while awaiting arrival of the communitys emergency medical services responders. The primary endpoint is the number of OOH-CA victims who survive to hospital discharge. Secondary endpoints include neurological status, health-related quality of life (HRQL), cost, and cost-effectiveness. Data collection will last approximately 15 months and is expected to be completed in September 2003.

Association Between Poor Sleep, Fatigue, and Safety Outcomes in Emergency Medical Services Providers

Abstract Objective. To determine the association between poor sleep quality, fatigue, and self-reported safety outcomes among emergency medical services (EMS) workers. Methods. We used convenience sampling of EMS agencies and a cross-sectional survey design. We administered the 19-item Pittsburgh Sleep Quality Index (PSQI), 11-item Chalder Fatigue Questionnaire (CFQ), and 44-item EMS Safety Inventory (EMS-SI) to measure sleep quality, fatigue, and safety outcomes, respectively. We used a consensus process to develop the EMS-SI, which was designed to capture three composite measurements of EMS worker injury, medical errors and adverse events (AEs), and safety-compromising behaviors. We used hierarchical logistic regression to test the association between poor sleep quality, fatigue, and three composite measures of EMS worker safety outcomes. Results. We received 547 surveys from 30 EMS agencies (a 35.6% mean agency response rate). The mean PSQI score exceeded the benchmark for poor sleep (6.9, 95% confidence interval [CI] 6.6, 7.2). More than half of the respondents were classified as fatigued (55%, 95% CI 50.7, 59.3). Eighteen percent of the respondents reported an injury (17.8%, 95% CI 13.5, 22.1), 41% reported a medical error or AE (41.1%, 95% CI 36.8, 45.4), and 90% reported a safety-compromising behavior (89.6%, 95% CI 87, 92). After controlling for confounding, we identified 1.9 greater odds of injury (95% CI 1.1, 3.3), 2.2 greater odds of medical error or AE (95% CI 1.4, 3.3), and 3.6 greater odds of safety-compromising behavior (95% CI 1.5, 8.3) among fatigued respondents versus nonfatigued respondents. Conclusions. In this sample of EMS workers, poor sleep quality and fatigue are common. We provide preliminary evidence of an association between sleep quality, fatigue, and safety outcomes.