Heemun Kwok

The Process of Prehospital Airway Management: Challenges and Solutions During Paramedic Endotracheal Intubation

Objectives:Endotracheal intubation success rates in the prehospital setting are variable. Our objective was to describe the challenges encountered and corrective actions taken during the process of endotracheal intubation by paramedics. Design:Analysis of prehospital airway management using a prospective registry that was linked to an emergency medical services administrative database. Setting:Emergency medical services system serving King County, Washington, 2006–2011. Paramedics in this system have the capability to administer neuromuscular blocking agents to facilitate intubation (i.e., rapid sequence intubation). Patients:A total of 7,523 patients more than 12 years old in whom paramedics attempted prehospital endotracheal intubation. Interventions:None. Measurements and Main Results:An intubation attempt was defined as the introduction of the laryngoscope into the patient’s mouth, and the attempt concluded when the laryngoscope was removed from the mouth. Endotracheal intubation was successful on the first attempt in 77% and ultimately successful in 99% of patients (7,433 of 7,523). Paramedics used a rapid sequence intubation strategy on 54% of first attempts. Among the subset with a failed first attempt (n = 1,715), bodily fluids obstructing the laryngeal view (50%), obesity (28%), patient positioning (17%), and facial or spinal trauma (6%) were identified as challenges to intubation. A variety of adjustments were made to achieve intubation success, including upper airway suctioning (used in 43% of attempts resulting in success), patient repositioning (38%), rescue bougie use (19%), operator change (16%), and rescue rapid sequence intubation (6%). Surgical cricothyrotomy (0.4%, n = 27) and bag-valve-mask ventilation (0.8%, n = 60) were rarely performed by paramedics as final rescue airway strategies. Conclusions:Airway management in the prehospital setting has substantial challenges. Success can require a collection of adjustments that involve equipment, personnel, and medication often in a simultaneous fashion.

Pediatric Intubation by Paramedics in a Large Emergency Medical Services System: Process, Challenges, and Outcomes

STUDY OBJECTIVE Pediatric intubation is a core paramedic skill in some emergency medical services (EMS) systems. The literature lacks a detailed examination of the challenges and subsequent adjustments made by paramedics when intubating children in the out-of-hospital setting. We undertake a descriptive evaluation of the process of out-of-hospital pediatric intubation, focusing on challenges, adjustments, and outcomes. METHODS We performed a retrospective analysis of EMS responses between 2006 and 2012 that involved attempted intubation of children younger than 13 years by paramedics in a large, metropolitan EMS system. We calculated the incidence rate of attempted pediatric intubation with EMS and county census data. To summarize the intubation process, we linked a detailed out-of-hospital airway registry with clinical records from EMS, hospital, or autopsy encounters for each child. The main outcome measures were procedural challenges, procedural success, complications, and patient disposition. RESULTS Paramedics attempted intubation in 299 cases during 6.3 years, with an incidence of 1 pediatric intubation per 2,198 EMS responses. Less than half of intubations (44%) were for patients in cardiac arrest. Two thirds of patients were intubated on the first attempt (66%), and overall success was 97%. The most prevalent challenge was body fluids obscuring the laryngeal view (33%). After a failed first intubation attempt, corrective actions taken by paramedics included changing equipment (33%), suctioning (32%), and repositioning the patient (27%). Six patients (2%) experienced peri-intubation cardiac arrest and 1 patient had an iatrogenic tracheal injury. No esophageal intubations were observed. Of patients transported to the hospital, 86% were admitted to intensive care and hospital mortality was 27%. CONCLUSION Pediatric intubation by paramedics was performed infrequently in this EMS system. Although overall intubation success was high, a detailed evaluation of the process of intubation revealed specific challenges and adjustments that can be anticipated by paramedics to improve first-pass success, potentially reduce complications, and ultimately improve clinical outcomes.

Does Preexisting Antiplatelet Treatment Influence Postthrombolysis Intracranial Hemorrhage in Community‐treated Ischemic Stroke Patients? An Observational Study

OBJECTIVES Intracranial hemorrhage (ICH) after acute stroke thrombolysis is associated with poor outcomes. Previous investigations of the relationship between preexisting antiplatelet use and the safety of intravenous (IV) thrombolysis have been limited by low event rates. The objective of this study was to determine whether preexisting antiplatelet therapy increased the risk of ICH following acute stroke thrombolysis. The primary hypothesis was that antiplatelet use would not be associated with radiographic evidence of ICH after controlling for relevant confounders. METHODS Consecutive cases of thrombolysis patients treated in the emergency department (ED) were identified using multiple methods. Retrospective data were collected from four hospitals from 1996 to 2004 and 24 other hospitals from 2007 to 2010 as part of a cluster-randomized trial. The same chart abstraction tool was used during both time periods, and data were subjected to numerous quality control checks. Hemorrhages were classified using a prespecified methodology: ICH was defined as presence of hemorrhage in radiographic interpretations of follow-up imaging (primary outcome). Symptomatic ICH (sICH) was defined as radiographic ICH with associated clinical worsening. A multivariable logistic regression model was constructed to adjust for clinical factors previously identified to be related to postthrombolysis ICH. Sensitivity analyses were conducted where the unadjusted and adjusted results from this study were combined with those of previously published external studies on this topic via meta-analytic techniques. RESULTS There were 830 patients included, with 47% having documented preexisting antiplatelet treatment. The mean (± standard deviation [SD]) age was 69 (± 15) years, and the cohort was 53% male. The unadjusted proportion of patients with any ICH was 15.1% without antiplatelet use and 19.3% with antiplatelet use (absolute risk difference = 4.2%, 95% confidence interval [CI] = -1.2% to 9.6%); for sICH this was 6.1% without antiplatelet use and 9% with antiplatelet use (absolute risk difference = 3.1%, 95% CI = -1% to 6.7%). After adjusting for confounders, antiplatelet use was not significantly associated with radiographic ICH (odds ratio [OR] = 1.1, 95% CI = 0.8 to 1.7) or sICH (OR = 1.3, 95% CI = 0.7 to 2.2). In patients 81 years and older, there was a higher risk of radiographic ICH (absolute risk difference = 11.9%, 95% CI = 0.1% to 23.6%). The meta-analyses combined the findings of this investigation with previous similar work and found increased unadjusted risks of radiographic ICH (absolute risk difference = 4.9%, 95% CI = 0.7% to 9%) and sICH (absolute risk difference = 4%, 95% CI = 2.3% to 5.6%). The meta-analytic adjusted OR of sICH for antiplatelet use was 1.6 (95% CI = 1.1 to 2.4). CONCLUSIONS The authors did not find that preexisting antiplatelet use was associated with postthrombolysis ICH or sICH in this cohort of community treated patients. Preexisting tobacco use, younger age, and lower severity were associated with lower odds of sICH. The meta-analyses demonstrated small, but statistically significant increases in the absolute risk of radiographic ICH and sICH, along with increased odds of sICH in patients with preexisting antiplatelet use.

Clinical Policy: Critical Issues in the Evaluation of Adult Patients With Suspected Transient Ischemic Attack in the Emergency Department

This clinical policy from the American College of Emergency Physicians addresses key issues for adults presenting to the emergency department with suspected transient ischemic attack. A writing subcommittee conducted a systematic review of the literature to derive evidence-based recommendations to answer the following clinical questions: (1) In adult patients with suspected transient ischemic attack, are there clinical decision rules that can identify patients at very low short-term risk for stroke who can be safely discharged from the emergency department? (2) In adult patients with suspected transient ischemic attack, what imaging can be safely delayed from the initial emergency department workup? (3) In adult patients with suspected transient ischemic attack, is carotid ultrasonography as accurate as neck computed tomography angiography or magnetic resonance angiography in identifying severe carotid stenosis? (4) In adult patients with suspected transient ischemic attack, can a rapid emergency department-based diagnostic protocol safely identify patients at short-term risk for stroke? Evidence was graded and recommendations were made based on the strength of the available data.

Short ECG segments predict defibrillation outcome using quantitative waveform measures

AIM Quantitative waveform measures of the ventricular fibrillation (VF) electrocardiogram (ECG) predict defibrillation outcome. Calculation requires an ECG epoch without chest compression artifact. However, pauses in CPR can adversely affect survival. Thus the potential use of waveform measures is limited by the need to pause CPR. We sought to characterize the relationship between the length of the CPR-free epoch and the ability to predict outcome. METHODS We conducted a retrospective investigation using the CPR-free ECG prior to first shock among out-of-hospital VF cardiac arrest patients in a large metropolitan region (n=442). Amplitude Spectrum Area (AMSA) and Median Slope (MS) were calculated using ECG epochs ranging from 5s to 0.2s. The relative ability of the measures to predict return of organized rhythm (ROR) and neurologically-intact survival was evaluated at different epoch lengths by calculating the area under the receiver operating characteristic curve (AUC) using the 5-s epoch as the referent group. RESULTS Compared to the 5-s epoch, AMSA performance declined significantly only after reducing epoch length to 0.2s for ROR (AUC 0.77-0.74, p=0.03) and with epochs of ≤0.6s for neurologically-intact survival (AUC 0.72-0.70, p=0.04). MS performance declined significantly with epochs of ≤0.8s for ROR (AUC 0.78-0.77, p=0.04) and with epochs ≤1.6s for neurologically-intact survival (AUC 0.72-0.71, p=0.04). CONCLUSION Waveform measures predict defibrillation outcome using very brief ECG epochs, a quality that may enable their use in current resuscitation algorithms designed to limit CPR interruption.

Ventricular fibrillation waveform measures combined with prior shock outcome predict defibrillation success during cardiopulmonary resuscitation

AIM Amplitude Spectrum Area (AMSA) and Median Slope (MS) are ventricular fibrillation (VF) waveform measures that predict defibrillation shock success. Cardiopulmonary resuscitation (CPR) obscures electrocardiograms and must be paused for analysis. Studies suggest waveform measures better predict subsequent shock success when combined with prior shock success. We determined whether this relationship applies during CPR. METHODS AMSA and MS were calculated from 5-second pre-shock segments with and without CPR, and compared to logistic models combining each measure with prior return of organized rhythm (ROR). RESULTS VF segments from 692 patients were analyzed during CPR before 1372 shocks and without CPR before 1283 shocks. Combining waveform measures with prior ROR increased areas under receiver operating characteristic curves for AMSA/MS with CPR (0.66/0.68 to 0.73/0.74, p<0.001) and without CPR (0.71/0.72 to 0.76/0.76, p<0.001). CONCLUSIONS Prior ROR improves prediction of shock success during CPR, and may enable waveform measure calculation without chest compression pauses.

An accurate method for real-time chest compression detection from the impedance signal

OBJECTIVE Real-time feedback improves CPR performance. Chest compression data may be obtained from an accelerometer/force sensor, but the impedance signal would serve as a less costly, universally available alternative. The objective is to assess the performance of a method which detects the presence/absence of chest compressions and derives CPR quality metrics from the impedance signal in real-time at 1s intervals without any latency period. METHODS Defibrillator recordings from cardiac arrest cases were divided into derivation (N=119) and validation (N=105) datasets. With the force signal as reference, the presence/absence of chest compressions in the impedance signal was manually annotated (reference standard). The method classified the impedance signal at 1s intervals as Chest Compressions Present, Chest Compressions Absent or Indeterminate. Accuracy, sensitivity and specificity for chest compression detection were calculated for each case. Differences between method and reference standard chest compression fractions and rates were calculated on a minute-to-minute basis. RESULTS In the validation set, median accuracy was 0.99 (IQR 0.98, 0.99) with 2% of 1s intervals classified as Indeterminate. Median sensitivity and specificity were 0.99 (IQR 0.98, 1.0) and 0.98 (IQR 0.95, 1.0), respectively. Median chest compression fraction error was 0.00 (IQR -0.01, 0.00), and median chest compression rate error was 1.8 (IQR 0.6, 3.3) compressions per minute. CONCLUSION A real-time method detected chest compressions from the impedance signal with high sensitivity and specificity and accurately estimated chest compression fraction and rate. Future investigation should evaluate whether an impedance-based guidance system can provide an acceptable alternative to an accelerometer-based system.

Rhythm profiles and survival after out-of-hospital ventricular fibrillation cardiac arrest

OBJECTIVE Treatment: protocols for cardiac arrest rely upon rhythm analyses performed at two-minute intervals, neglecting possible rhythm changes during the intervening period of CPR. Our objective was to describe rhythm profiles (patterns of rhythm transitions during two-minute CPR cycles) following attempted defibrillation and to assess their relationship to survival. METHODS The study included out-of-hospital cardiac arrest cases presenting with ventricular fibrillation from 2011 to 2015. The rhythm sequence was annotated during two-minute CPR cycles after the first and second shocks of each case, and the rhythm profile of each sequence was classified. We calculated absolute survival differences among rhythm profiles with the same rhythm at the two-minute check. RESULTS Of 569 rhythm sequences after the first shock, 46% included a rhythm transition. Overall survival was 47%, and survival proportion varied by rhythm at the two-minute check: ventricular fibrillation (46%), organized (58%) and asystole (20%). Survival was similar between profiles which ended with an organized rhythm at the two-minute check. Likewise, survival was similar between profiles with asystole at the two-minute check. However, in patients with ventricular fibrillation at the two-minute check, survival was twice as high in those with a transient organized rhythm (69%) compared to constant ventricular fibrillation (32%) or transient asystole (28%). CONCLUSION Rhythm transitions are common after attempted defibrillation. Among patients with ventricular fibrillation at the subsequent two-minute check, transient organized rhythm during the preceding two-minute CPR cycle was associated with favorable survival, suggesting distinct physiologies that could serve as the basis for different treatment strategies.

Clinical Policy: Critical Issues in the Evaluation and Management of Emergency Department Patients With Suspected Non–ST-Elevation Acute Coronary Syndromes

&NA; This clinical policy from the American College of Emergency Physicians addresses key issues in the evaluation and management of patients with suspected non–ST‐elevation acute coronary syndromes. A writing subcommittee conducted a systematic review of the literature to derive evidence‐based recommendations to answer the following clinical questions: (1) In adult patients without evidence of ST‐elevation acute coronary syndrome, can initial risk stratification be used to predict a low rate of 30‐day major adverse cardiac events? (2) In adult patients with suspected acute non–ST‐elevation acute coronary syndrome, can troponin testing within 3 hours of emergency department presentation be used to predict a low rate of 30‐day major adverse cardiac events? (3) In adult patients with suspected non–ST‐elevation acute coronary syndrome in whom acute myocardial infarction has been excluded, does further diagnostic testing (eg, provocative, stress test, computed tomography angiography) for acute coronary syndrome prior to discharge reduce 30‐day major adverse cardiac events? (4) Should adult patients with acute non–ST‐elevation myocardial infarction receive immediate antiplatelet therapy in addition to aspirin to reduce 30‐day major adverse cardiac events? Evidence was graded and recommendations were made based on the strength of the available data.

Clinical Policy: Emergency Department Management of Patients Needing Reperfusion Therapy for Acute ST-Segment Elevation Myocardial Infarction

Ischemic heart disease is the leading cause of death in the world. More than half a million patients present to emergency departments across the United States each year with ST-segment elevation myocardial infarctions. Timely reperfusion is critical to saving myocardium at risk. Multiple studies have been conducted that demonstrate that improved care processes are linked to improved survival in patients having an acute myocardial infarction. This clinical policy from the American College of Emergency Physicians addresses key issues in reperfusion for patients with acute ST-segment elevation myocardial infarction. A writing subcommittee conducted a systematic review of the literature to derive evidence-based recommendations to answer the following clinical questions: (1) In adult patients having an ST-segment elevation myocardial infarction, are there patients for whom treatment with fibrinolytic therapy decreases the incidence of major adverse cardiac events when percutaneous coronary intervention is delayed? (2) In adult patients having an ST-segment elevation myocardial infarction, does transfer to a percutaneous coronary intervention center decrease the incidence of major adverse cardiac events? (3) In adult patients undergoing reperfusion therapy, should opioids be avoided to prevent adverse outcomes? Evidence was graded and recommendations were made based on the strength of the available data.