Scott Youngquist

Is all ventricular fibrillation the same? A comparison of ischemically induced with electrically induced ventricular fibrillation in a porcine cardiac arrest and resuscitation model.

Objectives:The standard porcine cardiac arrest model uses electrical induction of ventricular fibrillation. Reported restoration of spontaneous circulation and survival rates in this model are as high as 90% for ventricular fibrillation durations of 7–10 mins, values substantially greater than rates in the clinical population (i.e., 20% to 30%). A high first shock success rate, infrequent refibrillation, and short times for restoration of spontaneous circulation are typical of the model. The purpose of this study was to determine whether ischemic induction of ventricular fibrillation in swine followed by standard advanced cardiac life support would result in short-term outcomes approximating those observed in human victims of out-of-hospital ventricular fibrillation. Design:Randomized comparative trial. Setting:Translational research laboratory. Subjects:Domestic swine (n = 40, mean weight 40 ± 4 kg, range 34–47 kg) of both genders. Interventions:Swine were instrumented and randomized to either electrical ventricular fibrillation induction or ischemic ventricular fibrillation, produced by balloon occlusion of the mid-left anterior descending coronary artery (n = 20 per group). Transthoracic impedance was measured and 30 &OHgr; added in series for all animals. The balloon remained inflated during resuscitation efforts in ischemic ventricular fibrillation animals. After 7 mins of ventricular fibrillation, cardiopulmonary resuscitation was initiated and defibrillation was attempted 1 min later. Epinephrine and antiarrhythmics were administered as per guidelines. Resuscitation was terminated if restoration of spontaneous circulation had not occurred after 15 mins of advanced cardiac life support. Measurements and Main Results:Although the number of countershocks required to initially terminate ventricular fibrillation was not different (electrical ventricular fibrillation 1.9 ± 1.6, ischemic ventricular fibrillation 2.4 ± 2.0), the refibrillation rate was higher in the ischemic ventricular fibrillation group (4.9 ± 4 vs. 0.8 ± 1 episodes/animal, p < .001), resulting in a greater number of shocks before restoration of spontaneous circulation (total shocks for ischemic ventricular fibrillation 9.4 ± 5.6 vs. electrical ventricular fibrillation 2.7 ± 2.2, p < .001). Time to restoration of spontaneous circulation was longer in the ischemic ventricular fibrillation group (430 ± 234 secs vs. 149 ± 120 secs, p < .001). Restoration of spontaneous circulation rates were not different (electrical ventricular fibrillation 90% vs. ischemic ventricular fibrillation 65%). However, survival to 6 hrs was greater in the electrical ventricular fibrillation group (18 of 20, 90%) than in the ischemic ventricular fibrillation group (8 of 20, 40%, p = .002). Conclusions:Resuscitation from ischemic ventricular fibrillation is more difficult than electrical ventricular fibrillation and is characterized by greater time to restoration of spontaneous circulation, frequent refibrillation, greater number of countershocks, higher epinephrine dose during resuscitation efforts, profound cardiac dysfunction, and a short-term survival rate approaching clinical experience. Ischemically induced ventricular fibrillation is a more clinically relevant model for the evaluation of resuscitation interventions.

Paramedic Self-efficacy and Skill Retention in Pediatric Airway Management

OBJECTIVES The objectives were to determine the effect of pediatric airway management training on paramedic self-efficacy and skill performance and to determine which of several retraining methods is superior. METHODS A total of 2,520 paramedics were trained to proficiency in pediatric bag-mask ventilation (BMV) and endotracheal intubation (ETI) on mannequins. Subjects were a convenience sample of 245 (10% of original cohort) presenting for voluntary retraining. A total of 212 of 245 (87%) completed skills testing. Self-efficacy was measured prior to and following initial training and retraining events. Paramedics were assigned to control (no retraining), videotape presentation, self-directed learning, or instructor-facilitated lecture and demonstration retraining. Following retraining, BMV and ETI skills were tested. RESULTS Paramedics from low-call-volume areas reported lower baseline self-efficacy and derived larger increases with training, but also experienced the most decline between training events. Pass rates for BMV and ETI were 66% (139/211) and 42% (88/212), respectively. However, overall cohort self-efficacy was maintained over the study period. In ordinal regression modeling, only the lecture and demonstration method was superior to control, with an odds ratio (OR) of achieving higher scores of 2.5 (95% confidence interval [CI] = 1.2 to 5.2) for BMV and 5.2 (95% CI = 2.4 to 11.2) for ETI. Poor performance with ETI but not BMV was associated with time elapsed since training (p = 0.01). Self-efficacy ratings were not predictive of skill performance. CONCLUSIONS Training provides increases in self-efficacy, particularly among paramedics from low-call-volume areas. A gap exists between self-efficacy and skill performance, in that self-efficacy may be maintained even when skill performance declines. Pediatric airway skills decay quickly, ETI skills drop off more significantly than BMV skills, and a lecture and demonstration format seems superior to other retraining methods investigated.

A Comparison of Door-to-balloon Times and False-positive Activations between Emergency Department and Out-of-hospital Activation of the Coronary Catheterization Team

OBJECTIVES The objectives were to compare the proportion of false-positive activations and intervention times between emergency department (ED) and field-based activation of the coronary catheterization laboratory (cath) team for emergency medical services (EMS) patients identified by out-of-hospital (OOH) 12-lead electrocardiogram (ECG) with ST-segment elevation myocardial infarction (STEMI). METHODS This was a retrospective review of prospectively collected continuous quality improvement data at a single, urban, academic medical center. By protocol, weekday activation of the cath team occurred based on OOH notification of a computer-interpreted OOH ECG indicating potential STEMI. Night and weekend activation occurred at the discretion of the attending emergency physician (EP) after advanced ED notification and after patient arrival and assessment. Basic demographic information and cardiac risk factors were recorded, as well as door-to-balloon (DTB) and ultimate diagnosis. RESULTS From May 2007 through March 2008, there were 23 field activations and 33 ED activations. There was no difference in demographic or clinical characteristics between the two groups. In the field activation group, 9/23 (39%) were false-positives, while 3/33 (9%) were false-positives in the ED activation group (30% higher absolute difference in the field activation group, 95% confidence interval [CI] = 8% to 52%, p = 0.02). OOH times and time spent in the ED were similar between the two groups. DTB times were 77 minutes for field activation and 68 minutes for ED activation, respectively (difference 9 minutes, 95% CI = -9 to 27). CONCLUSIONS Emergency physician activation of the cath team results in a lower proportion of false-positive activations without clearly sacrificing DTB time when compared to field activation based solely on the results of the OOH ECG.

First “Glass” Education: Telementored Cardiac Ultrasonography Using Google Glass- A Pilot Study

OBJECTIVES The objective of this study was to determine the feasibility of telementored instruction in bedside ultrasonography (US) using Google Glass. The authors sought to examine whether first-time US users could obtain adequate parasternal long axis (PSLA) views to approximate ejection fraction (EF) using Google Glass telementoring. METHODS This was a prospective, randomized, single-blinded study. Eighteen second-year medical students were randomized into three groups and tasked with obtaining PSLA cardiac imaging. Group A received real-time telementored education through Google Glass via Google Hangout from a remotely located expert. Group B received bedside education from the same expert. Group C represented the control and received no instruction. Each subject was given 3 minutes to obtain a best PSLA cardiac imaging using a portable GE Vscan. Image clips obtained by each subject were stored. A second expert, blinded to instructional mode, evaluated images for adequacy and assigned an image quality rating on a 0 to 10 scale. RESULTS Group A was able to obtain adequate images six out of six times (100%) with a median image quality rating of 7.5 (interquartile range [IQR] = 6 to 10) out of 10. Group B was also able to obtain adequate views six out of six times (100%), with a median image quality rating of 8 (IQR = 7 to 9). Group C was able to obtain adequate views one out of six times (17%), with a median image quality of 0 (IQR = 0 to 2). There were no statistically significant differences between Group A and Group B in the achievement of adequate images for E-point septal separation measurement or in image quality. CONCLUSIONS In this pilot/feasibility study, novice US users were able to obtain adequate imaging to determine a healthy patients EF through telementored education using Google Glass. These preliminary data suggest telementoring as an adequate means of medical education in bedside US. This conclusion will need to be validated with larger, more powerful studies including evaluation of pathologic findings and varying body habitus among models.

Diagnosis of appendicitis by bedside ultrasound in the ED

BACKGROUND Computed tomography (CT) has largely become standard of care for diagnosing appendicitis at the expense of increased patient radiation exposure, cost, and time to surgical intervention. To date, there are very limited data on the accuracy of bedside ultrasound (BUS) for the diagnosis of appendicitis in adults. OBJECTIVE The objective of this study is to evaluate test characteristics of BUS for diagnosis of acute appendicitis in the emergency department. METHODS Data were prospectively collected on 97 cases of suspected appendicitis, which had BUS performed by trained residents with attending supervision between August 2011 and November 2013. All BUS interpretation and additional diagnostic imaging were left to the discretion of the physician or surgical consultants. A blinded ultrasound fellowship-trained physician reviewed all images after clinical treatment. Bedside ultrasound findings and patient outcomes were reported. RESULTS A total of 97 adult cases underwent diagnostic ultrasound scans for suspected appendicitis. Of 97 cases, 34 had acute appendicitis by surgery/pathology report. Twenty-four BUS were positive for acute appendicitis and 11 were nondiagnostic. Of 24 positive ultrasounds, 23 had appendicitis on pathology report. There was 1 false-positive result, yielding a sensitivity of 67.65% (95% confidence limits, 49.5%-82.6%) and a specificity of 98.41% (95% confidence limits, 91.4%-99.7%). Of 23 positive BUS, 12 cases went to the Operating Room without an abdominal CT yielding a 12% reduction in CT utilization. If all positive BUS went to the OR without a CT scan, this would yield a 24% reduction in CT utilization. CONCLUSIONS Bedside ultrasound may be an appropriate initial test to evaluate patients with suspected acute appendicitis in the emergency department.

Is the tumour necrosis factor-alpha response following resuscitation gender dependent in the swine model?

INTRODUCTION Reperfusion results in a proinflammatory cytokine response, as has been observed following resuscitation from cardiac arrest. Variations in the inflammatory response have been shown to be gender dependent and mediated by steroid hormones. The purpose of this study was to determine whether the tumour necrosis factor-alpha response following resuscitation was gender dependent. METHODS Anaesthetized swine (15 males and 15 females, weighs 32-47 kg) underwent 7 min of electrically induced cardiac arrest, followed by conventional resuscitation and then measurement of tumour necrosis factor-alpha by enzyme-linked immunosorbent assay at intervals for up to 3h. Testosterone and 17-estradiol were measured in 8 males and 8 females. RESULTS In all animals 17-estradiol was undetectable. Testosterone exceeded the lower limit of detection in 3 females and 1 male. Levels of tumour necrosis factor-alpha were higher in males than females, from 30 min after resuscitation to 3h. In females, tumour necrosis factor-alpha levels were significantly higher than control values only at 15 min following restoration of circulation; the levels in males demonstrated marked inter-animal variation. CONCLUSIONS In this swine model, males demonstrated an augmented post-resuscitation tumour necrosis factor-alpha response when compared with females. This difference was not related to steroid hormone levels.

Children and Adults With Frequent Hospitalizations for Asthma Exacerbation, 2012-2013: A Multicenter Observational Study.

BACKGROUND Earlier studies reported that many patients were frequently hospitalized for asthma exacerbation. However, there have been no recent multicenter studies to characterize this patient population with high morbidity and health care utilization. OBJECTIVE To examine the proportion and characteristics of children and adults with frequent hospitalizations for asthma exacerbation. METHODS A multicenter chart review study of patients aged 2 to 54 years who were hospitalized for asthma exacerbation at 1 of 25 hospitals across 18 US states during the period 2012 to 2013 was carried out. The primary outcome was frequency of hospitalizations for asthma exacerbation in the past year (including the index hospitalization). RESULTS The cohort included 369 children (aged 2-17 years) and 555 adults (aged 18-54 years) hospitalized for asthma exacerbation. Over the 12-month period, 36% of the children and 42% of the adults had 2 or more (frequent) hospitalizations for asthma exacerbation. Among patients with frequent hospitalizations, guideline-recommended outpatient management was suboptimal. For example, among adults, 32% were not on inhaled corticosteroids at the time of index hospitalization and 75% had no evidence of a previous evaluation by an asthma specialist. At hospital discharge, among adults with frequent hospitalizations who had used no controller medications previously, 37% were not prescribed inhaled corticosteroids. Likewise, during a 3-month postdischarge period, 64% of the adults with frequent hospitalizations were not referred to an asthma specialist. Although the proportion of patients who did not receive these guideline-recommended outpatient care appeared higher in adults, these preventive measures were still underutilized in children; for example, 38% of the children with frequent hospitalizations were not referred to asthma specialist after the index hospitalization. CONCLUSIONS This multicenter study of US patients hospitalized with asthma exacerbation demonstrated a disturbingly high proportion of patients with frequent hospitalizations and ongoing evidence of suboptimal longitudinal asthma care.

Cardiac Function and the Proinflammatory Cytokine Response After Recovery From Cardiac Arrest in Swine

Increased levels of cytokines have been reported after resuscitation from cardiac arrest. We hypothesized that proinflammatory cytokines, released in response to ischemia/reperfusion, increase following resuscitation and play a role in post-cardiac arrest myocardial dysfunction. Ventricular fibrillation (VF) was induced by coronary occlusion in 20 swine. After 7 min of VF, resuscitation was performed as per guidelines. Plasma levels of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, and IL-6 were measured 15 min after the start of resuscitation in all animals and at intervals of 6 h in resuscitated animals. Intravascular pressures and cardiac output (CO) were also recorded. TNF-alpha abruptly increased after resuscitation, peaking at 15 min following return of spontaneous circulation, and declined to baseline levels after 3 h. IL-1beta increased more slowly, reaching a maximum 2 h after reperfusion. IL-6 concentrations were not significantly different from control values at any time point. Males demonstrated greater elevations of TNF-alpha and IL-1beta than females. Stroke work was significantly depressed at all time points with a nadir at 15-30 min after reperfusion, corresponding to the peak TNF-alpha values. The anti-TNF-alpha antibody infliximab attenuated the decrease in myocardial function observed 30 min after reperfusion. TNF-alpha increases during recovery from cardiac arrest are associated with depression of left ventricle (LV) function. The effect of TNF-alpha can be attenuated by anti-TNF-alpha antibodies.

Bundled postconditioning therapies improve hemodynamics and neurologic recovery after 17 min of untreated cardiac arrest

OBJECTIVE Ischemic postconditioning (stutter CPR) and sevoflurane have been shown to mitigate the effects of reperfusion injury in cardiac tissue after 15min of ventricular fibrillation (VF) cardiac arrest. Poloxamer 188 (P188) has also proven beneficial to neuronal and cardiac tissue during reperfusion injury in human and animal models. We hypothesized that the use of stutter CPR, sevoflurane, and P188 combined with standard advanced life support would improve post-resuscitation cardiac and neurologic function after prolonged VF arrest. METHODS Following 17min of untreated VF, 20 pigs were randomized to Control treatment with active compression/decompression (ACD) CPR and impedance threshold device (ITD) (n=8) or Bundle therapy with stutter ACD CPR+ITD+sevoflurane+P188 (n=12). Epinephrine and post-resuscitation hypothermia were given in both groups per standard protocol. Animals that achieved return of spontaneous circulation (ROSC) were evaluated with echocardiography, biomarkers, and a blinded neurologic assessment with a cerebral performance category score. RESULTS Bundle therapy improved hemodynamics during resuscitation, reduced need for epinephrine and repeated defibrillation, reduced biomarkers of cardiac injury and end-organ dysfunction, and increased left ventricular ejection fraction compared to Controls. Bundle therapy also improved rates of ROSC (100% vs. 50%), freedom from major adverse events (50% vs. 0% at 48h), and neurologic function (42% with mild or no neurologic deficit and 17% achieving normal function at 48h). CONCLUSIONS Bundle therapy with a combination of stutter ACD CPR, ITD, sevoflurane, and P188 improved cardiac and neurologic function after 17min of untreated cardiac arrest in pigs. All studies were performed with approval from the Institutional Animal Care Committee of the Minneapolis Medical Research Foundation (protocol #12-11).

The central nervous system cytokine response to global ischemia following resuscitation from ventricular fibrillation in a porcine model

AIM OF THE STUDY Pro-inflammatory cytokines have been implicated as culprits in neurotoxicity following ischemia in small animal models of stroke. The aim of this study was to measure the central nervous system (CNS) cytokine response following resuscitation from ventricular fibrillation (VF) in a porcine model of cardiac arrest and global hypoxic ischemia. METHODS VF was induced electrically in 11 anesthetized swine. Following 7 min of untreated VF, animals were resuscitated. Cerebrospinal fluid (CSF) and serum was sampled prior to VF and at 60, 120, and 180 min post-resuscitation from which levels of TNF-alpha, IL-1 beta, and IL-6 were measured. Levels were also drawn in three sham pigs, instrumented but not fibrillated. RESULTS CSF levels of TNF-alpha rose following resuscitation and were associated with CSF levels of IL-1 beta (p=0.0002). CSF levels of all cytokines except TNF-alpha were associated with their serum counterparts. CONCLUSIONS Measurable increases in pro-inflammatory cytokines in the CSF follow resuscitation from cardiac arrest in this porcine model. The CNS response TNF-alpha and IL-1 beta are associated. However, serum levels of TNF-alpha did not seem to predict CSF levels in this study, consistent with the concept of immune privilege of the CNS.