Matthew C. Gratton

Improved Patient Survival Using a Modified Resuscitation Protocol for Out-of-Hospital Cardiac Arrest

Background— Cardiac arrest continues to have poor survival in the United States. Recent studies have questioned current practice in resuscitation. Our emergency medical services system made significant changes to the adult cardiac arrest resuscitation protocol, including minimizing chest compression interruptions, increasing the ratio of compressions to ventilation, deemphasizing or delaying intubation, and advocating chest compressions before initial countershock. Methods and Results— This retrospective observational cohort study reviewed all adult primary ventricular fibrillation and pulseless ventricular tachycardia cardiac arrests 36 months before and 12 months after the protocol change. Primary outcome was survival to discharge; secondary outcomes were return of spontaneous circulation and cerebral performance category. Survival of out-of-hospital arrest of presumed primary cardiac origin improved from 7.5% (82 of 1097) in the historical cohort to 13.9% (47 of 339) in the revised protocol cohort (odds ratio, 1.80; 95% confidence interval, 1.19 to 2.70). Similar increases in return of spontaneous circulation were achieved for the subset of witnessed cardiac arrest patients with initial rhythm of ventricular fibrillation from 37.8% (54 of 143) to 59.6% (34 of 57) (odds ratio, 2.44; 95% confidence interval, 1.24 to 4.80). Survival to hospital discharge also improved from an unadjusted survival rate of 22.4% (32 of 143) to 43.9% (25 of 57) (odds ratio, 2.71; 95% confidence interval, 1.34 to 1.59) with the protocol. Of the 25 survivors, 88% (n=22) had favorable cerebral performance categories on discharge. Conclusions— The changes to our prehospital protocol for adult cardiac arrest that optimized chest compressions and reduced disruptions increased the return of spontaneous circulation and survival to discharge in our patient population. These changes should be further evaluated for improving survival of out-of-hospital cardiac arrest patients.

EFFECT OF PARAMEDIC EXPERIENCE ON OROTRACHEAL INTUBATION SUCCESS RATES

This studys objective was to determine the effect of paramedic experience on orotracheal intubation success in prehospital adult nontraumatic cardiac arrest patients. This retrospective study analyzed all attempted intubations of prehospital adult nontraumatic cardiac arrest patients between January 1, 1997 and April 30, 1997 in an urban, all ALS service. Data were abstracted from EMS reports and intubation data forms. Variables included months of experience, number of patients in whom intubation was attempted, number of intubation attempts, success per attempt, and success per patient. Ninety-eight paramedics performed 909 intubations on 1066 cardiac arrest patients, yielding an intubation success rate of 85.3%. The median months of experience was 59.5 (Range 5-223). The median number of patients in whom intubation was attempted per paramedic was 10 (Range 1-36). The mean intubation success rate per paramedic was 80.6% (+/- 22.4, 95% CI 76.1, 85.1). There was significant correlation between total number of patients in whom intubation was attempted and intubation success rate (p <.001, R = 0.32). There was no correlation between months of experience and intubation success rate. In conclusion, the number of patients in whom intubation was attempted per paramedic was significantly correlated with the intubation success rate. Months of experience per paramedic had no significant correlation with intubation success rate.

The accuracy of predicting cardiac arrest by emergency medical services dispatchers: the calling party effect.

OBJECTIVES To analyze the accuracy of paramedic emergency medical services (EMS) dispatchers in predicting cardiac arrest and to assess the effect of the caller party on dispatcher accuracy in an advanced life support, public utility model EMS system, with greater than 90,000 calls and greater than 60,000 transports per year. METHODS This was a retrospective analysis from January 1, 2000, through June 30, 2000, of 911 calls with dispatcher-assigned presumptive patient condition (PPC) or field diagnosis of cardiac arrest. Sensitivity and positive predictive value (PPV) of the PPC code for cardiac arrest by calling parties were calculated. Homogeneity of sensitivity and PPV of the PPC code for cardiac arrest by calling parties was studied with chi-square analysis. Relevant proportions, relative risk ratios, and associated 95% confidence intervals (95% CIs) were calculated. Students t-test was used to compare quality assurance scores between calling parties. RESULTS There were 506 patients included in the study. Overall sensitivity for dispatcher-assigned PPC of cardiac arrest was 68.3% (95% CI = 63.3% to 73.0%) with a PPV of 65.0% (95% CI = 60.0% to 69.7%). There was a significant difference in the PPV for the EMS dispatcher diagnosis of cardiac arrest depending on the type of caller (chi(2) = 17.34, p < 0.001). CONCLUSIONS A higher level of medical training may improve dispatch accuracy for predicting cardiac arrest. The type of calling party influenced the PPV of dispatcher-assigned condition.

Prospective determination of medical necessity for ambulance transport by paramedics.

OBJECTIVE It has been estimated that between 11% and 61% of ambulance transports to emergency departments are not medically necessary. This studys objective was to analyze paramedic ability to determine the medical necessity of ambulance transport to the emergency department. METHODS Paramedics prospectively assessed adult patients transported to an emergency department during a six-week period. The setting was an urban, all advanced life support, public utility model emergency medical services (EMS) system with 58,000 transports per year. Paramedics determined medical necessity of patient transport based on the following five criteria: 1) need for out-of-hospital intervention; 2) need for expedient transport; 3) potential for self-harm; 4) severe pain; or 5) other. On arrival in the emergency department, the emergency physician made a blinded determination based on the same criteria. Kappa statistics were used to assess agreement. RESULTS Data forms were completed on 825 of 1,420 (58%) patients transported. Emergency physicians determined 248 (30%) transports were not necessary, paramedics 236 (29%), with agreement in 76.2% (K=0.42) of cases. Paramedics undertriaged 92 patients (11%). Rates of agreement on the five criteria were: 1) 71.9% (K=0.43); 2) 77.7% (K=0.22); 3) 89.6% (K=0.40); 4) 89.6 (K=0.32); and 5) 82.2% (K=0.29). CONCLUSIONS Paramedics and emergency physicians agreed that a significant percentage of patients did not require ambulance transport to the emergency department. Despite only moderate agreement regarding which patients needed transport, the undertriage rate was low.

Ambulance arrival to patient contact: The hidden component of prehospital response time intervals

STUDY OBJECTIVE To determine the time between ambulance arrival at the scene to paramedic arrival at the patient (arrival to patient contact) and the effect of barriers to paramedic movement on this time interval. DESIGN A prospective, observational study. Time intervals were collected by independent third-party riders on emergency (Code 1 and Code 2) calls. Potential barriers to paramedic movement were recorded. SETTING Public utility model urban emergency medical services system. TYPE OF PARTICIPANTS Two hundred thirty-two emergency ambulance calls were observed, and data were analyzed from 216. INTERVENTIONS None. RESULTS The median arrival-to-patient contact interval for all calls was 1.33 minutes (interquartile range, 0.67 to 4.13 minutes). Barriers prolonged the arrival-to-patient contact interval (P < .001, Kolmogorov-Smirnov test). The median arrival-to-patient contact interval was 2.29 minutes (1.01 to 4.82 minutes) for 122 runs with barriers and 0.82 minutes (0.37 to 1.96 minutes) for 94 runs without barriers. CONCLUSION The arrival-to-patient contact interval adds a variable and potentially lengthy amount of time to the total prehospital response time interval, and barriers impeding paramedic movement to the patient prolong this time interval. In 25% of all observed paramedic calls, the arrival-to-patient contact interval was more than four minutes. Measurement of the time from ambulance arrival on the scene to paramedic arrival at the patient is necessary to appropriately determine the relationship among total prehospital response time, paramedic interventions, and patient outcome.

P ROSPECTIVE D ETERMINATION OF M EDICAL N ECESSITY FOR A MBULANCE T RANSPORT BY P ARAMEDICS

Objective. It has been estimated that between 11% and 61% of ambulance transports to emergency departments are not medically necessary. This studys objective was to analyze paramedic ability to determine the medical necessity of ambulance transport to the emergency department. Methods. Paramedics prospectively assessed adult patients transported to an emergency department during a six-week period. The setting was an urban, all advanced life support, public utility model emergency medical services (EMS) system with 58,000 transports per year. Paramedics determined medical necessity of patient transport based on the following five criteria: 1) need for out-of-hospital intervention; 2) need for expedient transport; 3) potential for self-harm; 4) severe pain; or 5) other. On arrival in the emergency department, the emergency physician made a blinded determination based on the same criteria. Kappa statistics were used to assess agreement. Results. Data forms were completed on 825 of 1,420 (58%) patients transported. Emergency physicians determined 248 (30%) transports were not necessary, paramedics 236 (29%), with agreement in 76.2% (K = 0.42) of cases. Paramedics undertriaged 92 patients (11%). Rates of agreement on the five criteria were: 1) 71.9% (K = 0.43); 2) 77.7% (K = 0.22); 3) 89.6% (K = 0.40); 4) 89.6 (K = 0.32); and 5) 82.2% (K = 0.29). Conclusions. Paramedics and emergency physicians agreed that a significant percentage of patients did not require ambulance transport to the emergency department. Despite only moderate agreement regarding which patients needed transport, the undertriage rate was low.

Populations at risk for intubation nonattempt and failure in the prehospital setting.

Objectives. Pediatric cardiac arrest patients andadult traumatic arrest patients are perceived as more difficult to endotracheally intubate than adult cardiac arrest patients. The study hypothesis was that these populations were at higher risk of endotracheal intubation failure compared with adult cardiac arrest patients andthat paramedics would more frequently defer attempts to intubate these patients. Methods. This was a retrospective, observational study analyzing oral endotracheal intubations on pediatric cardiac arrest, adult traumatic arrest, andadult cardiac arrest patients over 66 months. Homogeneity of intubation nonattempt andendotracheal intubation failure was studied with chi-square analysis. Relative risks (RRs) with 95% confidence intervals (CIs) were used to compare pediatric cardiac arrest with adult traumatic arrest with adult cardiac arrest nonattempt rates andendotracheal intubation failure rates. Results. 2,669 oral endotracheal intubations were included. There was a significant difference in intubation nonattempts andintubation failure between the combined pediatric cardiac arrest andadult traumatic arrest groups andthe adult cardiac arrest cohort (RR 7.24, 95% CI 5.73, 9.16 for nonattempt; RR = 2.33, 95% CI 1.93, 2.83 for intubation failure). Both groups individually showed significant risk for intubation nonattempt andendotracheal intubation failure compared with adult cardiac arrest, with the pediatric cohort at higher risk for failure andthe adult traumatic arrest cohort at higher risk for nonattempt. Conclusions. There was significant risk of intubation nonattempt andintubation failure in the pediatric cardiac arrest andadult traumatic arrest cohorts compared with the adult cardiac arrest population, with the pediatric cohort being at particularly high risk for intubation failure andthe adult traumatic arrest cohort at higher risk for nonattempt.

DOSE EFFECTIVENESS AND SAFETY OF BUTORPHANOL IN ACUTE MIGRAINE HEADACHE

This study was undertaken to compare the effectiveness and safety of three dosage levels of butorphanol in 52 patients with acute, severe migraine headache. After baseline evaluation, patients were given a dose of butorphanol 1.0, 2.0, or 3.0 mg intramuscularly on a double‐blind basis. Assessments of pain intensity and pain relief using 100 mm linear analog scales (LAS), vital signs, and medication side effects were made at 15, 30, 45, and 60 minutes after the dose. All three treatment groups were similar in baseline characteristics. Each dose of butorphanol demonstrated a significant decrease in pain intensity LAS compared to baseline and increase in pain relief LAS over the observation period. The majority of analgesic response was observed at the first (i.e., 15‐min) assessment. Doses of 2.0 and 3.0 mg produced significantly greater analgesia than did 1.0 mg at all posttreatment evaluations. No significant difference was apparent between the 2.0‐ and 3.0‐mg doses. Adverse cardiovascular and respiratory depressant effects were not observed. An analgesic response to butorphanol 2.0 and 3.0 mg is clearly and rapidly evident and near maximum 30–45 minutes after administration. We conclude that in these doses butorphanol provides effective and safe analgesia for patients with acute migraine headache.

Vehicle-at-Scene-to-Patient-Access Interval Measured With Computer-Aided Dispatch

STUDY OBJECTIVE To determine whether the vehicle-at-scene-to-patient-access (VSPA) interval could be measured by means of crew reporting to a computer-aided dispatch operation. DESIGN A prospective demonstration-proof-methodology pilot study using crew reporting of access time on emergency calls. SETTING An urban, public utility model (a type of EMS system), all-ALS system. PARTICIPANTS Six ambulance crews (four day and two night). INTERVENTIONS Times were collected by radio reporting. A survey was to be completed for each call. RESULTS Two hundred ninety-two calls met study criteria; 181 had corresponding surveys. Crew reporting compliance ranged from 52.8% to 94%. Poor radio transmission was cited infrequently as a reason for noncompliance. The median VSPA interval for all calls was 1.3 minutes (interquartile range, .8 to 2.6 minutes). Twenty-five percent of calls had intervals of more than 2.5 minutes, and 10% had an interval of more than 5 minutes. CONCLUSION Our study suggests that it is feasible for ambulance crews to report patient access times. Methods to improve the consistency and frequency of crew reporting should be considered. The VSPA access interval varies in length and is not normally distributed.

Unexpected ALS Procedures on Non-Emergency Ambulance Calls: The Value of a Single-Tier System

Background: In a single-tier, advanced-life-support (ALS) emergency medical service (EMS) system, ALS-trained staff in ALS-equipped vehicles respond to all ambulance calls. In some two-tier systems, basic life support (BLS) vehicles respond to calls which are determined initially to be non-emergency based on dispatcher triage. I emergency requiring ALS is discovered (or recognized) by BLS personnel, then a subsequent ALS response can be requested. Purpose: The purpose of this study was to determine the frequency of ALS care provided on ambulance calls initially dispatched as non-emergency. Setting: A single-tier, all-ALS provider, EMS system, serving an urban population of 475,000 with an annual response volume of 45,000 calls. Methods: A retrospective review of all prehospital transports initially dispatched as non-emergency from 1 January 1989 to 1 January 1990 that resulted in an ALS intervention being performed was conducted. An ALS intervention was defined as, “administration of a medication, endotracheal intubation, attempted IV insertion, and/or ECG monitoring.” Results: A total of 6,362 non-emergency calls were identified; of these 309 (5%) were upgraded to emergency while the responding unit was in route. Of 6,053 non-emergency calls remaining, 710 (11.7%) involved the provision of one or more ALS interventions. Of these, 296 (42%) received an IV, 24 (3%) a medication, and three (0.4%) were intubated. Calls that were upgraded by dispatchers required one or more interventions in 144/309 calls (46.6%). This was statistically significantly different than for the non-upgraded calls. Conclusion: Despite the use of strict dispatching protocols, 11.7% of patients prioritized as non-emergent unexpectedly received ALS care after evaluation by ALS personnel. These results add support for the use of a single-tier, ALS ambulance system.