A randomized controlled feasibility trial comparing safety and effectiveness of prehospital pacing versus conventional treatment: 'PrePACE'.

OBJECTIVE: To evaluate the feasibility of a prehospital randomized controlled trial comparing transcutaneous pacing (TCP) with dopamine for unstable bradycardia. METHODS: Unstable bradycardic patients who failed to respond to a fluid bolus and up to 3mg atropine were enrolled. The intervention was dopamine or TCP with crossover to dopamine if TCP failed. The primary outcome was survival to discharge or 30 days. Randomization compliance, safety, follow-up rates, primary outcome, and sample size requirements were assessed. RESULTS: Of 383 patients with unstable bradycardia, 151 (39%) failed to respond to atropine or fluid and were eligible for enrollment and 82 (55%) were correctly enrolled. Fifty-five (36%) of eligible patients could not be enrolled for practical reasons; 3 had advance directives, 32 met inclusion criteria on arrival at hospital and in 20 cases, paramedics chose not to enroll based on the circumstances of the case. The remaining 13 were missed cases; 8 were missing randomization envelopes and in 5, the paramedic forgot. Randomization compliance was 95% (78/82). Forty-two (51%) patients were randomized to TCP and seven of these crossed over to dopamine. Two cases were randomized but did not receive the intervention; either due to lack of time or loss of IV access. Three adverse events occurred in each group. Survival to discharge or 30 days in hospital was 70% (28/40) and 69% (29/42) in the dopamine and TCP groups, respectively with 100% follow up. To detect a 10% relative difference in 30 days survival between treatment arms, a sample size of 690 per group would be required. CONCLUSIONS: It is feasible to conduct a prehospital randomized controlled trial of TCP for unstable bradycardia and a definitive trial would require a multi-centre study.

Responses to written notification during out-of-hospital care trials using waiver of informed consent.

BACKGROUND: Resuscitation research has been allowed to proceed using waiver of consent when compliance with guidelines is assured. In these circumstances, institutional review boards (IRBs) may request notification of enrolled patients. OBJECTIVES: To describe the notification process developed with IRB feedback and implemented in two out-of-hospital randomized controlled trials (RCTs) in a large urban setting. METHODS: This was a descriptive review of two RCTs recruiting a total of 620 patients: the Out-of-hospital Cardiac Arrest Rectilinear Biphasic to Monophasic Damped Sine Defibrillation Waveforms with Advanced Life Support Intervention Trial (ORBIT), which compared rectilinear biphasic and monophasic damped sine waveform for out-of-hospital cardiac arrest, and the Prehospital Pacing versus Conventional Treatment Effectiveness Trial (PrePACE), which compared dopamine and transcutaneous pacing for unstable bradycardia. RESULTS: The ORBIT study enrolled 538 patients. In 44 (8%) patients, contact information could not be obtained. Notification was attempted for 494 (92%) patients; 48 (10%) letters were returned to sender. Researchers were contacted by telephone regarding 37 (8%) subjects: 16 (43%) requested information, 14 (38%) responded positively, and one (3%) did not return follow-up calls. Overall, two (0.4%) were withdrawn from the study. The PrePACE study enrolled 82 subjects. Contact information was unavailable for one (1%). For the remaining 81 patients, four (5%) letters were returned to sender. Researchers were contacted regarding ten (13%) subjects: seven (70%) requested information, two (20%) responded positively, and one (10%) did not return follow-up calls. No patient was withdrawn from the study. CONCLUSIONS: Contact information may be difficult to obtain for up to 20% of out-of-hospital critical patients. In 8% to 13% of cases, patients or designates contacted researchers; most feedback was positive. Frequently, non-study-related information was requested, consuming significant resources. Using this method, fewer than 1% of patients were withdrawn from the studies.

Out-of-hospital cardiac arrest rectilinear biphasic to monophasic damped sine defibrillation waveforms with advanced life support intervention trial (ORBIT).

BACKGROUND: Although biphasic defibrillation waveforms appear to be superior to monophasic waveforms in terminating VF, their relative benefits in out-of-hospital resuscitation are incompletely understood. Prior comparisons of defibrillation waveform efficacy in out-of-hospital cardiac arrest (OHCA) are confined to patients presenting in a shockable rhythm and resuscitated by first responder (basic life support). This effectiveness study compared monophasic and biphasic defibrillation waveform for conversion of ventricular arrhythmias in all OHCA treated with advance life support (ALS). METHODS AND RESULTS: This prospective randomized controlled trial compared the rectilinear biphasic (RLB) waveform with the monophasic damped sine (MDS) waveform, using step-up energy levels. The study enrolled OHCA patients requiring at least one shock delivered by ALS providers, regardless of initial presenting rhythm. Shock success was defined as conversion at 5s to organized rhythm after one to three escalating shocks. We report efficacy results for the cohort of patients treated by ALS paramedics who presented with an initially shockable rhythm who had not received a shock from a first responder (MDS: n=83; RLB: n=86). Shock success within the first three ascending energy shocks for RLB (120, 150, 200J) was superior to MDS (200, 300, 360J) for patients initially presenting in a shockable rhythm (52% versus 34%, p=0.01). First shock conversion was 23% and12%, for RLB and MDS, respectively (p=0.07). There were no significant differences in return of spontaneous circulation (47% versus 47%), survival to 24h (31% versus 27%), and survival to discharge (9% versus 7%). Mean 24h survival rates of bystander witnessed events showed differences between waveforms in the early circulatory phase at 4-10 min post event (mean (S.D.) RLB 0.45 (0.07) versus MDS 0.31 (0.06), p=0.0002) and demonstrated decline as time to first shock increased to 20 min. CONCLUSION: Shock success to an organized rhythm comparing step-up protocol for energy settings demonstrated the RLB waveform was superior to MDS in ALS treatment of OHCA. Survival rates for both waveforms are consistent with current theories on the circulatory and metabolic phases of out-of-hospital cardiac arrest.