P. Richard Verbeek

Validation of a universal prehospital termination of resuscitation clinical prediction rule for advanced and basic life support providers

BACKGROUND Prehospital termination of resuscitation rules have been derived for Emergency Medical Technician-Paramedics providing advanced life support care and defibrillation-only Emergency Medical Technicians providing basic life support care. We sought to externally validate each rule on a prospective cohort of prehospital cardiac arrest patients to determine if either rule could be proposed as a universal prehospital termination of resuscitation rule. METHODS Investigators at the University of Toronto performed a secondary cohort analysis of data prospectively collected for the Resuscitation Outcomes Consortium Epistry-Cardiac Arrest trial from 1 April 2006 to 1 April 2007 by one site. The diagnostic test characteristics and predicted transportation rate were calculated for each rule. RESULTS Of the 2415 patients with cardiac arrest of presumed cardiac etiology, the advanced life support rule recommended termination of resuscitation for 743 patients. No survivors were identified in this group. It had a specificity of 100% for recommending transport of potential survivors, a positive predictive value of 100% for death and a predicted transport rate of 69%. The basic life support rule recommended termination of resuscitation for 1302 patients, with no survivors. This rule had a specificity of 100%, a positive predictive value of 100% and a predicted transport rate of 46%. CONCLUSIONS Implementing the basic life support rule as a universal termination of resuscitation clinical prediction rule would result in a lower overall transport rate without missing any potential survivors. The universal rule would recommend termination of resuscitation when there was no return of spontaneous circulation prior to transport, no shock was given and the arrest was not witnessed by Emergency Medical Services personnel. This rule may be useful for emergency medical services systems with mixed levels of providers responding to cardiac arrest patients.

The impact of peri-shock pause on survival from out-of-hospital shockable cardiac arrest during the Resuscitation Outcomes Consortium PRIMED trial.

BACKGROUND Previous research has demonstrated significant relationships between peri-shock pause and survival to discharge from out-of-hospital shockable cardiac arrest (OHCA). OBJECTIVE To determine the impact of peri-shock pause on survival from OHCA during the ROC PRIMED randomized controlled trial. METHODS We included patients in the ROC PRIMED trial who suffered OHCA between June 2007 and November 2009, presented with a shockable rhythm and had CPR process data for at least one shock. We used multivariable logistic regression to determine the association between peri-shock pause duration and survival to hospital discharge. RESULTS Among 2006 patients studied, the median (IQR) shock pause duration was: pre-shock pause 15s (8, 22); post-shock pause 6s (4, 9); and peri-shock pause 22.0 s (14, 31). After adjusting for Utstein predictors of survival as well as CPR quality measures, the odds of survival to hospital discharge were significantly higher for patients with pre-shock pause <10s (OR: 1.52, 95% CI: 1.09, 2.11) and peri-shock pause <20s (OR: 1.82, 95% CI: 1.17, 2.85) when compared to patients with pre-shock pause ≥ 20s and peri-shock pause ≥ 40s. Post-shock pause was not significantly associated with survival to hospital discharge. Results for neurologically intact survival (Modified Rankin Score ≤ 3) were similar to our primary outcome. CONCLUSIONS In patients with cardiac arrest presenting in a shockable rhythm during the ROC PRIMED trial, shorter pre- and peri-shock pauses were significantly associated with higher odds of survival. Future cardiopulmonary education and technology should focus on minimizing all peri-shock pauses.

Trends in Short- and Long-Term Survival Among Out-of-Hospital Cardiac Arrest Patients Alive at Hospital Arrival

Background— Out-of-hospital cardiac arrest (OHCA) is associated with a poor prognosis and poses a significant burden to the healthcare system, but few studies have evaluated whether OHCA incidence and survival have changed over time. Methods and Results— A population-based cohort study was conducted, including 34 291 OHCA patients >20 years of age who were transported alive to the emergency department of an acute-care hospital from April 1, 2002, to March 31, 2012, in Ontario, Canada. Patients with life-threatening trauma and those who died before hospital arrival were excluded. The overall age- and sex-standardized incidence of OHCA patients who were transported alive was 36 cases per 100 000 persons and did not significantly change over the study period. Cardiac risk factor prevalence increased significantly, whereas the rate of most cardiovascular conditions decreased significantly. The 30-day survival improved from 9.4% in 2002 to 13.6% in 2011; 1-year survival improved from 7.7% to 11.8% (P<0.001). Patients hospitalized in 2011 were significantly more likely to survive 30 days (adjusted odds ratio, 1.47 [95% CI, 1.22–1.77]) and 1 year (adjusted odds ratio, 1.55 [95% CI, 1.27–1.91]) compared with 2002. A significant interaction between temporal trends in survival improvement and age group was observed in which the improvement in survival was largest in the youngest age groups. Conclusions— OHCA patients who were transported alive are increasingly likely to have cardiovascular risk factors but less likely to have previous cardiovascular conditions. The overall incidence of OHCA patients transported to hospital alive did not change over the past decade. Short- and longer-term survival after OHCA has substantially improved, with younger patients experiencing the greatest improvement.

Predictive Value of the Ontario Prehospital Stroke Screening Tool for the Identification of Patients with Acute Stroke

Background. In 2005, a prehospital stroke screening tool was implemented in Toronto, Ontario, Canada. Patients identified by paramedics through the use of this tool in the field were transported to a regional stroke center under an acute stroke protocol. Objective. To determine the positive predictive value (PPV) of the Ontario Prehospital Stroke Screening Tool for identification of acute stroke at a single stroke center. Methods. We conducted a retrospective analysis of consecutive patients transported to a regional stroke center under the prehospital acute stroke protocol over a 12-month period. Final diagnoses, treatments, andoutcomes were abstracted from a provincial registry. Rates of fibrinolysis were compared with those for the 12-month period prior to implementation of the stroke protocol. Results. Three hundred twenty-five patients were triaged under the emergency medical services (EMS) acute stroke protocol over the study period. The PPV of the screening tool was 89.5% (95% confidence interval [CI]: 85.7–92.7%) for acute stroke. Thirty-four patients (11%) had nonstroke conditions, with the most common being seizure (4%). The rate of administration of tissue plasminogen activator (tPA) for all patients with suspected stroke increased from 5.9% to 10.1% (p = 0.04) compared with the rate in the 12-month period prior to implementation of the acute stroke protocol. The tPA rate for patients arriving under the stroke protocol was 17.2%. Most patients (75%) receiving tPA arrived from outside the hospital catchment area. Conclusions. In this preliminary study, the Ontario Prehospital Stroke Screening Tool had a high PPV for acute stroke andappeared to be effective for identifying patients who required triage to a single regional stroke center. Following implementation of a citywide acute stroke protocol using this screening tool, we observed an increase in the number of patients who were eligible for andreceived fibrinolysis at our stroke center

Implementation trial of the basic life support termination of resuscitation rule: Reducing the transport of futile out-of-hospital cardiac arrests

BACKGROUND The basic life support (BLS) termination of resuscitation (TOR) rule recommends transport and continued resuscitation when cardiac arrest is witnessed by EMT-Ds, or there is a return of spontaneous circulation, or a shock is given, and prior studies have suggested the transport rate should fall to 37%. METHODS AND RESULTS This real-time prospective multi-center implementation trial evaluated the BLS TOR rule for compliance, transport rate and provider and physician comfort. Both provider and physician noted their decision-making rationale and ranked their comfort on a 5-point Likert scale. Functional survival was measured at discharge. Of 2421 cardiac arrests, 953 patients were eligible for the rule, which was applied correctly for 755 patients (79%) of which 388 were terminated. 565 patients were transported resulting in a reduction of the transport rate from 100% (historical control) to 59% (p<0.001). The BLS TOR rule was not followed in 198 eligible patients (21%) and they were all transported despite meeting the criteria to terminate. Providers cited 241 reasons for non-compliance: family distress, short transport time interval, younger age and public venue. All 198 transported patients, non-compliant with the rule, died. Both providers and physicians were comfortable with using the rule to guide TOR (median [IQR] of 5 [4,5]; p<0.001). CONCLUSIONS This implementation trial confirmed the accuracy of the BLS TOR rule in identifying futile out-of-hospital cardiac arrest (OHCA) resuscitations, significantly reduced the transport rate of futile OHCA and most providers and physicians were comfortable following the rules recommendations.

Heliox does not improve FEV1 in acute asthma patients

Thirteen patients with an acute exacerbation of asthma and pre-treatment FEV1 between 20%-60% of predicted were tested to determine whether a blend of 70:30, helium:oxygen (heliox) improved FEV1. No pretreatment with bronchodilators occurred. The change in absolute and predicted FEV1 was measured after five minutes of breathing heliox. It was found that the absolute FEV1 during heliox was not significantly different from the absolute FEV1 before heliox. The difference between the absolute FEV1 during and before heliox was found to be -0.04 l. The percent predicted FEV1 during heliox was 40.8% +/- 13.0% vs. 41.5% +/- 11.9% before heliox. The difference between the percent predicted FEV1 during and before heliox was found to be -0.7%. We conclude that 70:30 heliox does not improve FEV1 in these patients.

Serial Prehospital 12-Lead Electrocardiograms Increase Identification of ST-segment Elevation Myocardial Infarction

Abstract Background. Many prehospital protocols require acquisition of a single 12-lead electrocardiogram (ECG) when assessing a patient for ST-segment elevation myocardial infarction (STEMI). However, it is known that ECG evidence of STEMI can evolve over time. Objectives. To determine how often the first and, if necessary, second or third prehospital ECGs identified STEMI, and the time intervals associated with acquiring these ECGs and arrival at the emergency department (ED). Methods. We retrospectively analyzed 325 consecutive prehospital STEMIs identified between June 2008 and May 2009 in a large third-service emergency medical services (EMS) system. If the first ECG did not identify STEMI, protocol required a second ECG just before transport and, if necessary, a third ECG before entering the receiving ED. Paramedics who identified STEMI at any time bypassed participating local EDs, taking patients directly to the percutaneous coronary intervention (PCI) center. Paramedics used computerized ECG interpretation with STEMI diagnosis defined as an “acute MI” report by GE/Marquette 12-SL software in ZOLL E-series defibrillator/cardiac monitors (ZOLL Medical, Chelmsford, MA). We recorded the time of each ECG, and the ordinal number of the diagnostic ECG. We then determined the number of cases and frequency of STEMI diagnosis on the first, second, or third ECG. We also measured the interval between ECGs and the interval from the initial positive ECG to arrival at the ED. Results. STEMI was identified on the first prehospital ECG in 275 cases, on the second ECG in 30 cases, and on the third ECG in 20 cases (cumulative percentages of 84.6%, 93.8%, and 100%, respectively). For STEMIs identified on the second or third ECG, 90% were identified within 25 minutes after the first ECG. The median times from identification of STEMI to arrival at the ED were 17.5 minutes, 11.0 minutes, and 0.7 minutes for STEMIs identified on the first, second, and third ECGs, respectively. Conclusions. A single prehospital ECG would have identified only 84.6% of STEMI patients. This suggests caution using a single prehospital ECG to rule out STEMI. Three serial ECGs acquired over 25 minutes is feasible and may be valuable in maximizing prehospital diagnostic yield, particularly where emergent access to PCI exists. Key words: prehospital emergency care; myocardial infarction; ECG; STEMI

Nontapering versus tapering prednisone in acute exacerbations of asthma: A pilot trial

Controversy exists as to whether or not the dose of prednisone should be tapered in patients discharged from the emergency department after initial treatment for an acute exacerbation of asthma. We assessed the rates of relapse and rebound in a group of 28 patients treated with a nontapering course of prednisone and compared their outcomes to an historical control group of 48 patients treated with a typical tapering course of prednisone. We found no significant difference in the rates of relapse or rebound between the nontapering dose patients and the tapering dose patients within either 21 days of discharge or within 10 days after stopping prednisone. Fifty-four percent of study patients reported adverse effects that could be attributed to prednisone. Our preliminary findings suggest that tapering of prednisone may not be needed in these patients.

Use of Treat-and-Release Medical Directives for Paramedics at a Mass Gathering

Introduction. Paramedics provide a substantial proportion of care at mass gatherings but do not typically release patients without physician assessment. Objective. To evaluate treat-and-release medical directives implemented at a large single-day summer rock concert. Methods. Medical directives allowed paramedics to administer acetaminophen, dimenhydrinate, diphenhydramine, or polymyxin B ointment for common complaints without evidence of serious illness on history or examination. After treatment, patients were released or transferred to a medical facility according to predefined criteria. Patient demographics, chief complaint, treatment, anddisposition were obtained from paramedic records. To determine whether any patients released by paramedic subsequently required ambulance transport, all ambulance records were searched for a period of eight hours before to 24 hours after the event. Results. More than 450,000 people attended the concert, with 1,870 presenting for medical attention. Four hundred seven patients received medications under the directives. No disposition was recorded in 13 cases. Two hundred ninety-nine patients were treated with acetaminophen, of whom 269 (90.0%) were released and23 (7.7%) required additional care. Sixty-two patients received dimenhydrinate, 44 (71%) were released, and14 (23%) required transport. Thirty-six patients received diphenhydramine, and34 (94%) were released. Ten patients received polymyxin B andwere released. No patient released by paramedics was found to have later required ambulance transport. Conclusions. Treat-and-release medical directives for paramedics at mass gatherings may help divert patients from requiring care at a medical facility. Future research is needed to determine the safety (morbidity andmortality) of these directives. Key words: emergency medical services; paramedic; treat andrelease; mass gathering; medical directives.

Clinical Events and Treatment in Prehospital Patients with ST-segment Elevation Myocardial Infarction

Abstract Background. Little is known about clinically important events and advanced care treatment that patients with ST-segment elevation myocardial infarction (STEMI) encounter in the prehospital setting. Objectives. We sought to determine the proportion of community patients with STEMI who experienced a clinically important event or received advanced care treatment prior to arrival at a designated percutaneous coronary intervention (PCI) laboratory or emergency department (ED). Methods. We reviewed 487 consecutive community patients with STEMI between May 2008 and June 2009. All patients were geographically within a single large “third-service” urban emergency medical services (EMS) system and were transported by paramedics with an advanced care scope of practice. We recorded predefined clinically important events and advanced care treatment that occurred in patients being transported directly to a PCI laboratory or ED (group 1) or interfacility transfer to a PCI laboratory (group 2). Results. One or more clinically important events occurred in 92 of 342 (26.9%) group 1 patients and nine of 145 (6.2%) group 2 patients. The most common were sinus bradycardia, hypotension, and cardiac arrest. Additionally, 33 of 342 (9.6%) group 1 and nine of 145 (6.2%) group 2 patients received one or more advanced care treatments. The most common were administration of morphine and administration of atropine. Eight group 1 patients and three group 2 patients received cardiopulmonary resuscitation (CPR) or defibrillation. Conclusions. Clinically important events and advanced care treatment are common in community STEMI patients undergoing prehospital transport or interfacility transfer to a PCI center. Several patients required CPR or defibrillation. Further research is needed to define the clinical experience of STEMI patients during the out-of-hospital phase and the scope of practice required of EMS providers to safely manage these patients. Key words: myocardial infarction; complications; emergency medical services; emergency treatment