Nichole Bosson

Survival and Neurologic Outcome after Out-of-Hospital Cardiac Arrest: Results One Year after Regionalization of Post-Cardiac Arrest Care in a Large Metropolitan Area

Abstract Background. Post-resuscitation care of cardiac arrest patients at specialized centers may improve outcome after out-of-hospital cardiac arrest (OOHCA). This study describes experience with regionalized care of resuscitated patients. Methods. Los Angeles (LA) County established regionalized cardiac care in 2006. Since 2010, protocols mandate transport of nontraumatic OOHCA patients with field return of spontaneous circulation (ROSC) to a STEMI Receiving Center (SRC) with a hypothermia protocol. All SRC report outcomes to a registry maintained by the LA County Emergency Medical Services (EMS) Agency. We report the first years data. The primary outcome was survival with good neurologic outcome, defined by a Cerebral Performance Category (CPC) score of 1 or 2. Results. The SRC treated 927 patients from April 2011 through March 2012 with median age 67; 38% were female. There were 342 patients (37%) who survived to hospital discharge. CPC scores were unknown in 47 patients. Of the 880 patients with known CPC scores, 197 (22%) survived to hospital discharge with a CPC score of 1 or 2. The initial rhythm was VF/VT in 311 (34%) patients, of whom 275 (88%) were witnessed. For patients with an initial shockable rhythm, 183 (59%) survived to hospital discharge and 120 (41%) had survival with good neurologic outcome. Excluding patients who were alert or died in the ED, 165 (71%) patients with shockable rhythms received therapeutic hypothermia (TH), of whom 67 (42%) had survival with good neurologic outcome. Overall, 387 patients (42%) received TH. In the TH group, the adjusted OR for CPC 1 or 2 was 2.0 (95%CI 1.2–3.5, p = 0.01), compared with no TH. In contrast, the proportion of survival with good neurologic outcome in the City of LA in 2001 for all witnessed arrests (irrespective of field ROSC) with a shockable rhythm was 6%. Conclusion. We found higher rates of neurologically intact survival from OOHCA in our system after regionalization of post-resuscitation care as compared to historical data.

Accuracy of Paramedic Broselow Tape Use in the Prehospital Setting

Abstract Background. The Broselow tape is widely used to rapidly estimate weight and facilitate proper medication dosing in pediatric patients. Objective. We aimed to determine the accuracy of prehospital use of the Broselow tape. Methods. We prospectively enrolled a consecutive sample of pediatric patients transported to the emergency department (ED) at Harbor–UCLA Medical Center from February 2008 to January 2009. Eligible subjects arrived via ambulance and were less than 145 cm tall, the upper limit of height for Broselow measurements. Subjects were excluded if they had a medical condition preventing proper measurement (e.g., contractures). Per Los Angeles County protocol, paramedics obtained a Broselow weight on all pediatric patients. The paramedic Broselow weight was compared with the ED Broselow weight and the ED scale weight, which was obtained unless mobilization was contraindicated. Accuracy was determined by assessing Bland-Altman plots and the Pearson correlation coefficient. As part of a sensitivity analysis, multiple imputation was used to account for missing data. Results. There were 572 subjects enrolled. The median age was 24 months (interquartile range [IQR] 10 to 49 months); 316 (55%) of the subjects were male. The weighted Cohens kappa assessing agreement between the paramedic and ED Broselow colors was 0.74 (95% confidence interval [CI] 0.68 to 0.79). The median difference between the paramedic Broselow weight and the scale weight was –0.10 kg (IQR –1.7 to 0.7). The accuracy of the paramedic Broselow weight when compared with the ED scale weight and the ED Broselow weight as defined by Pearsons correlation coefficient was 0.92 (95% CI 0.90 to 0.93) and 0.97 (95% CI 0.97 to 0.98), respectively. Multiple imputation for missing data did not alter the results. Conclusion. Paramedic Broselow weight correlates well with scale weight and ED Broselow weight. Paramedics can use the Broselow tape to accurately determine weight for pediatric patients in the prehospital setting.

Sex Differences in Survival From Out‐of‐Hospital Cardiac Arrest in the Era of Regionalized Systems and Advanced Post‐Resuscitation Care

Background The purpose of this study was to evaluate sex differences in out‐of‐hospital cardiac arrest (OHCA) characteristics, interventions, and outcomes. Methods and Results This is a retrospective analysis from a regionalized cardiac arrest system. Data on patients treated for OHCA are reported to a single registry, from which all adult patients were identified from 2011 through 2014. Characteristics, treatment, and outcomes were evaluated with stratification by sex. The adjusted odds ratio (OR) for survival with good neurological outcome (cerebral performance category 1 or 2) was calculated for women compared to men. There were 5174 out‐of‐hospital cardiac arrests (OHCAs; 3080 males and 2094 females). Women were older, median 71 (interquartile range [IQR], 59–82) versus 66 years (IQR, 55–78). Despite similar frequency of witnessed arrest, women were less likely to present with a shockable rhythm (22% vs 35%; risk difference [RD], 13%; 95% CI, 11–15), have ST‐segment elevation myocardial infarction (23% vs 32%; RD, 13%; 95% CI, 7–11), or receive coronary angiography (11% vs 25%; RD, 14%; 95% CI, 12–16), percutaneous coronary intervention (5% vs 14%; RD, 9%; 95% CI, 7–11), or targeted temperature management (33% vs 40%; RD, 7%; 95% CI, 4–10). Women had decreased survival to discharge (33% vs 40%; RD, 7%; 95% CI, 4–10) and a lower proportion of good neurological outcome (16% vs 24%; RD, 8%; 95% CI, 6–10). In multivariable modeling, female sex was not associated with decreased survival with good neurological outcome (OR, 0.9; 95% CI, 0.8–1.1). Conclusions Sex‐related differences in OHCA characteristics and treatment are predictors of survival outcome disparities. With adjustment for these factors, sex was not associated with survival or neurological outcome after OHCA.

Predictors of neurologic outcome in patients resuscitated from out-of-hospital cardiac arrest using classification and regression tree analysis.

The estimated survival rate of 8% to 10% after out-of-hospital cardiac arrest (OHCA) remains dismal. Few studies have addressed predictors of functional neurologic outcome after successful resuscitation. The objective of the study was to identify variables associated with favorable neurologic outcomes, defined by a Glasgow Coma Scale of 14 or 15, after OHCA. We used a propensity analysis and classification and regression tree model of 184 OHCA patients surviving to hospital admission at a cardiac arrest receiving center in Los Angeles County from 2008 to 2013. Forty-three patients (23%) had a favorable outcome, median age was 65 years (interquartile range [IQR] 54 to 76), and 98 (53%) were men. Sixty-six patients (36%) presented with a shockable rhythm. The majority were witnessed, either by a civilian (n=115, 63%) or a paramedic (n=25, 14%). Bystander cardiopulmonary resuscitation was performed on 84 patients (46%); median dose of epinephrine was 2 mg (IQR 1 to 3). Median time to return of spontaneous circulation was 21 minutes (IQR 16 to 29); the median lactate level was 5.2 mmol/L (IQR 2.8 to 9.2). Lower epinephrine doses (<1.5 mg) and lactate levels<5 mmol/L were predictive of a normal Glasgow Coma Scale, with 90.7% sensitivity (95% confidence interval [CI] 76.9% to 96.9%), 47.5% specificity (95% CI 39.1% to 56.1%), a positive predictive value of 34.5% (95% CI 31.6% to 46.1%), a negative predictive value of 94.4% (95% CI 85.5% to 98.2%), and an area under the curve of 0.89. The propensity score-adjusted logistic regression model demonstrated that receiving <1.5 mg of epinephrine was associated with a favorable neurologic outcome (odds ratio 3.3, 95% CI 1.1 to 10, p=0.04). In conclusion, for patients surviving to hospital admission, a good neurologic outcome was associated with having received <1.5 mg of epinephrine and a lactate level<5 mmol/L.

Treatment and Outcomes of ST Segment Elevation Myocardial Infarction and Out-of-Hospital Cardiac Arrest in a Regionalized System of Care Based on Presence or Absence of Initial Shockable Cardiac Arrest Rhythm

The aim of this study was to evaluate the treatment and outcomes of patients with ST-segment elevation myocardial infarctions complicated by out-of-hospital cardiac arrest in a regional system of care. In this retrospective study, the effect of the absence of an initial shockable arrest rhythm was analyzed. The primary end point of survival with good neurologic outcome in patients with and without an initial shockable arrest rhythm was adjusted for age, witnessed arrest, bystander cardiopulmonary resuscitation, and treatment with therapeutic hypothermia and percutaneous coronary intervention. One-hundred sixty-eight of 348 patients (49%) survived to hospital discharge. Patients with a shockable initial rhythm were more likely to receive therapeutic hypothermia (48% vs 37%, risk ratio 1.2, 95% confidence interval [CI] 1.0 to 1.5) and to be treated in the cardiac catheterization laboratory (80% vs 43%, risk ratio 2.8, 95% CI 2.0 to 3.8). The likelihood of survival with good neurologic outcome in patients with a shockable initial rhythm compared with those presenting without a shockable rhythm was 4.8 (95% CI 2.7 to 8.7). In patients who underwent percutaneous coronary intervention, the likelihood of survival with good neurologic outcome was higher (risk ratio 2.7, 95% CI 1.1 to 6.8) in those with a shockable rhythm. In conclusion, the absence of an initial shockable rhythm in patients with ST-segment elevation myocardial infarctions plus out-of-hospital cardiac arrest is associated with significantly worse survival and neurologic outcome. These differences persist despite application of therapies including therapeutic hypothermia and percutaneous coronary intervention within a regionalized system of care.

The Utility of Prehospital ECG Transmission in a Large EMS System

Abstract Background. Prehospital identification of STEMI and activation of the catheterization lab can improve door-to-balloon (D2B) times but may lead to decreased specificity and unnecessary resource utilization. The purpose of this study was to examine the effect of electrocardiogram (ECG) transmission on false-positive (FP) cath lab activations and time to reperfusion. Methods. This is a retrospective cohort from a registry in a large metropolitan area with regionalized cardiac care and emergency medical services (EMS) with ECG transmission capabilities. Thirty-four designated STEMI receiving centers (SRC) contribute to this registry, from which patients with a prehospital ECG software interpretation of myocardial infarction (MI) indicated by ****Acute MI****, or manufacturer equivalent, were identified between April 2011 and September 2013. Frequency of FP field activations (defined as not resulting in emergent percutaneous coronary intervention [PCI] or referral for CABG during hospital admission) for patients with ECG transmission received by the SRC was compared to a reference group without successful ECG transmission. FP field activations were compared to the baseline frequency of FP ED activations. We hypothesized that successful transmission would reduce FP field activation to ED activation levels. Door-to-balloon and first medical contact-to-balloon (FMC2B) times were compared. The protocol for field cath lab activation varied by institution. Results. There were 7,768 patients presenting with a prehospital ECG indicating MI. The ECG was received by the SRC for 2,156 patients (28%). Regardless of transmission, the cath lab was activated 77% of the time; this activation occurred from the field in 73% and 74% of the activations in the transmission and reference group, respectively. The overall proportion of FP activation was 57%. Among field activations, successful ECG transmission reduced the FP activation rate compared to without ECG transmission, 55% vs. 61% (RD = −6%, 95%CI −9, −3%). This led to an overall system reduction in FP activations of 5% (95%CI 2, 8%). ECG transmission had no effect on D2B and FMC2B time. Conclusion. Prehospital ECG transmission is associated with a small reduction in false-positive field activations for STEMI and had no effect on time to reperfusion in this cohort. Key words: emergency medical services; myocardial infarction; myocardial reperfusion; electrocardiography

Causes of Prehospital Misinterpretations of ST Elevation Myocardial Infarction

Abstract Objectives: To determine the causes of software misinterpretation of ST elevation myocardial infarction (STEMI) compared to clinically identified STEMI to identify opportunities to improve prehospital STEMI identification. Methods: We compared ECGs acquired from July 2011 through June 2012 using the LIFEPAK 15 on adult patients transported by the Los Angeles Fire Department. Cases included patients ≥18 years who received a prehospital ECG. Software interpretation of the ECG (STEMI or not) was compared with data in the regional EMS registry to classify the interpretation as true positive (TP), true negative (TN), false positive (FP), or false negative (FN). For cases where classification was not possible using registry data, 3 blinded cardiologists interpreted the ECG. Each discordance was subsequently reviewed to determine the likely cause of misclassification. The cardiologists independently reviewed a sample of these discordant ECGs and the causes of misclassification were updated in an iterative fashion. Results: Of 44,611 cases, 50% were male (median age 65; inter-quartile range 52–80). Cases were classified as 482 (1.1%) TP, 711 (1.6%) FP, 43371 (97.2%) TN, and 47 (0.11%) FN. Of the 711 classified as FP, 126 (18%) were considered appropriate for, though did not undergo, emergent coronary angiography, because the ECG showed definite (52 cases) or borderline (65 cases) ischemic ST elevation, a STEMI equivalent (5 cases) or ST-elevation due to vasospasm (4 cases). The sensitivity was 92.8% [95% CI 90.6, 94.7%] and the specificity 98.7% [95% CI 98.6, 98.8%]. The leading causes of FP were ECG artifact (20%), early repolarization (16%), probable pericarditis/myocarditis (13%), indeterminate (12%), left ventricular hypertrophy (8%), and right bundle branch block (5%). There were 18 additional reasons for FP interpretation (<4% each). The leading causes of FN were borderline ST-segment elevations less than the algorithm threshold (40%) and tall T waves reducing the ST/T ratio below threshold (15%). There were 11 additional reasons for FN interpretation occurring ≤3 times each. Conclusion: The leading causes of FP automated interpretation of STEMI were ECG artifact and non-ischemic causes of ST-segment elevation. FN were rare and were related to ST-segment elevation or ST/T ratio that did not meet the software algorithm threshold.

Re-examining outcomes after unsuccessful out-of-hospital resuscitation in the era of field termination of resuscitation guidelines and regionalized post-resuscitation care

BACKGROUND Dismal prognosis after failed out-of-hospital resuscitation has previously been demonstrated. Changes in resuscitation and post-resuscitation care may affect patient outcomes. We describe characteristics and outcomes of patients with out-of-hospital cardiac arrest (OOHCA) transported to specialty cardiac centers after failure of out-of-hospital interventions. METHODS In Los Angeles (LA) County, patients with non-traumatic OOHCA with return of spontaneous circulation (ROSC) are transported to specialized cardiac care centers. Outcomes are reported to a registry maintained by the LA County Emergency Medical Services (EMS) Agency. We report patient characteristics and outcomes for the subset of patients treated at these specialty centers in whom initial ROSC was achieved in the ED. The primary outcome was neurologically intact survival, defined by a cerebral performance category (CPC) score of 1 or 2. RESULTS 105 patients transported to the SRC after failure to achieve ROSC with out-of-hospital resuscitation were successfully resuscitated in the ED. The median age was 68 years (IQR 57-78); 74 (70%) were male. The presenting rhythm was ventricular fibrillation or ventricular tachycardia in 40 patients (38%) and 86 (82%) were witnessed. Twenty-two patients (21%) survived to hospital discharge. Of the 103 patients with known CPC scores, 13 (13% [95% CI 7-21%]) survived to hospital discharge with a CPC score of 1 or 2. No patient who survived with good neurologic outcome met criteria for termination of resuscitation in the field. CONCLUSION Failure of out-of-hospital resuscitation is not universally predictive of poor neurologic outcome.

Effect of Therapeutic Hypothermia on Survival and Neurologic Outcome in the Elderly

Old age is considered a negative prognostic factor after out-of-hospital cardiac arrest (OHCA). The purpose of this study was to assess the benefit of therapeutic hypothermia (TH) on survival and neurologic outcome in the elderly. This is a retrospective study of patients treated for OHCA from April 2011 to August 2013 in a regional cardiac system. Patients with return of spontaneous circulation (ROSC) are directed to designated cardiac receiving centers with established TH protocols. The decision to initiate TH is determined by the treating physician. All patients 65 years or older were identified. Patients were excluded if awake and responsive in the emergency department, died before hospital admission, or had preexisting coma. The adjusted odds ratio for survival with good neurologic outcome (defined as cerebral performance category [CPC] 1 or 2) was calculated for patients who received TH compared to a reference group without TH. There were 1612 patients, of whom 552 (34%) received TH. Median age was 78 (inter-quartile range [IQR] 71-85); 56% was male. 493 (31%) patients survived to hospital discharge, 266 (17%) with CPC of 1 or 2. Of 1292 patients considered for TH, 192 (25%) of 552 patients who received TH survived to hospital discharge and 97 (18%) with good neurologic outcome compared to 150 (20%) and 57 (8%), respectively, without TH. The adjusted odds ratio for survival with good neurologic outcome for TH was 2.0 (95% CI 1.3-3.3). TH is associated with improved neurologic outcome in the elderly population.

Implementation of a Titrated Oxygen Protocol in the Out-of-Hospital Setting

Oxygen is one of the most frequently-used therapeutic agents in medicine and the most commonly administered drug by prehospital personnel. There is increasing evidence of harm with too much supplemental oxygen in certain conditions, including stroke, chronic obstructive pulmonary disease (COPD), neonatal resuscitations, and in postresuscitation care. Recent guidelines published by the British Thoracic Society (BTS) advocate titrated oxygen therapy, but these guidelines have not been widely adapted in the out-of-hospital setting where high-flow oxygen is the standard. This report is a description of the implementation of a titrated oxygen protocol in a large urban-suburban Emergency Medical Services (EMS) system and a discussion of the practical application of this out-of-hospital protocol.