Adam R. Kellogg

A randomized comparison of cardiocerebral and cardiopulmonary resuscitation using a swine model of prolonged ventricular fibrillation

BACKGROUND Cardiocerebral resuscitation (CCR) is reportedly superior to cardiopulmonary resuscitation (CPR) for primary cardiac arrest in the prehospital setting. This study was done using a swine model of prolonged ventricular fibrillation (VF) to quantify the effect of the emergency medical services component of CCR with intraosseous access (CCR-IO) compared with standard CPR with intravenous access (CPR-IV) as it is typically performed during out-of-hospital cardiac arrest (OHCA) resuscitation in a prospective randomized fashion. METHODS Fifty-three animals were instrumented under anesthesia and VF was electrically induced. After 10 min of untreated VF, baseline characteristics were recorded, and animals were block randomized to one of two resuscitation schemes. The controls had mechanical chest compressions at 100/min with ventilations at a ratio of 30:2. Consistent with clinical practice, two 30-s pauses in chest compressions occurred to simulate attempts to accomplish endotracheal intubation at minutes 1 and 3 of CPR and successful IV access was simulated to occur three additional minutes after endotracheal intubation. The CCR group had continuous uninterrupted mechanical chest compressions at 100/min. No active ventilations were provided. A tibial IO needle was placed in real time for vascular access. Both groups received epinephrine (0.1 mg/kg) as soon as access became available followed by 2.5 min of chest compressions before the first 120 J rescue shock attempt. After successful rescue shock, standardized post-resuscitative care was provided to a 20-min endpoint. Failed rescue shock was followed by continued chest compressions with positive pressure ventilation in both groups, repeat doses of epinephrine (0.01 mg/kg) every 3 min, and rescue shock every minute as long as a shockable rhythm persisted. Group comparisons were assessed using descriptive statistics. Proportions with 95% confidence intervals were calculated for VF termination, ROSC, and survival. RESULTS Baseline characteristics and chemistries between the two groups at VF induction and after 10 min of non-treatment were mathematically the same. The proportions of VF termination (0.50 vs. 0.82), ROSC (0.30 vs. 0.59), and 20-min survival (0.19 vs. 0.40) all strongly favored the CCR-IO group. CONCLUSION In this swine model of witnessed VF arrest with no bystander-initiated resuscitation, CCR-IO resulted in substantial improvement in all three outcomes relative to typical emergency medical services provided CPR-IV.

A blinded, randomized controlled evaluation of an impedance threshold device during cardiopulmonary resuscitation in swine ,

BACKGROUND An impedance threshold device (ITD) has been designed to enhance circulation during CPR. A recent study suggests that the ITD does not improve hemodynamics and that it may actually worsen outcomes. We sought to independently assess the effect of the ITD on coronary perfusion pressure (CPP) and passive ventilation (PaCO(2) and PaO(2)) during standard CPR (S-CPR), and its impact on the return of spontaneous circulation (ROSC) and short-term survival in a blinded fashion. METHODS Thirty male swine were instrumented under anesthesia. Ventricular fibrillation (VF) was electrically induced. CPP was continuously recorded. After 8 min of untreated VF, baseline characteristics were documented and S-CPR initiated. After 3 cycles of S-CPR, an ABG was drawn and drugs were given. Following 6 additional cycles of S-CPR, an ABG was drawn and the first rescue shock was delivered. Group comparisons were assessed using descriptive statistics. Proportions with 95% confidence intervals were calculated for outcomes. RESULTS Baseline characteristics between the two groups were the same. The mean CPP in the ITD group was 51.2 mmHg [95% CI: 37.7, 64.7] compared to 50.2 mmHg [95% CI: 37.0, 63.4] in the sham group. The PaCO(2) and PaO(2) were 68 Torr [95% CI: 55.7, 79.5] and 103 Torr [95% CI: 76, 129] in the ITD group and 59 Torr [95% CI: 49.1, 68.5] and 137 Torr [95% CI: 83, 191] in the sham group. The rate of ROSC was 14/15 in both groups and 13 animals in each groups survived. CONCLUSIONS In this independent blinded study, use of the active ITD had no significant impact on CPP, passive ventilation, or outcomes compared to the sham device.

The feasibility of inducing mild therapeutic hypothermia after cardiac resuscitation using iced saline infusion via an intraosseous needle

OBJECTIVE This study was done, using a swine model of prolonged ventricular fibrillation out-of-hospital cardiac arrest, to determine the feasibility of inducing therapeutic hypothermia after successful resuscitation by giving an intraosseous infusion of iced saline. METHODS This study was IACUC approved. Liter bags of normal saline, after being refrigerated for at least 24h, were placed in an ice filled cooler. Female Yorkshire swine weighing between 27 and 35 kg were sedated and instrumented under general anesthesia. A temperature probe was inserted 10 cm into the esophagus. Ventricular fibrillation was electrically induced and allowed to continue untreated for 10 min. Animals were randomized to one of two resuscitation schemes for the primary study (N=53). One group had central intravenous access for drug delivery and the other had an intraosseous needle inserted into the proximal tibia for drug administration. Animals in which spontaneous circulation was restored were immediately cooled, for this secondary study, by means of a rapid, pump-assisted infusion of 1L of iced saline either through the intraosseous needle (n=8), the central access (n=6), or a peripheral intravenous catheter (n=7) in a systematic, non-randomized fashion. Room, animal, and saline temperatures were recorded at initiation and upon completion of infusion. The data were analyzed descriptively using Stata SE v8.1 for Macintosh. RESULTS The baseline characteristics of all three groups were mathematically the same. The average ambient room temperature during the experimental sessions was 25.5 degrees C (SD=1.3 degrees C). There were no statistically significant differences between the three groups with regard to saline temperature, rate of infusion, or decrease in core body temperature. The decrease in core temperature for the intraosseous group was 2.8 degrees C (95% CI=1.8, 3.8) over the infusion period. CONCLUSIONS Mild therapeutic hypothermia can be effectively induced in swine after successful resuscitation of prolonged ventricular fibrillation by infusion of iced saline through an IO needle.

Diagnostic Reasoning for ST-Segment Elevation Myocardial Infarction (STEMI) Interpretation Is Preserved Despite Fatigue.

BACKGROUND Fatigue and sleepiness contribute to medical errors, although the effect of circadian disruption and fatigue on diagnostic reasoning skills is largely unknown. OBJECTIVE To determine whether circadian disruption and fatigue negatively affect the emergency medicine (EM) residents ability to make important clinical decisions based on electrocardiogram (ECG) interpretation. METHODS Senior EM residents at 2 programs completed a questionnaire consisting of various measures of fatigue followed by an ECG test packet of ST-segment elevation myocardial infarction (STEMI) and STEMI mimics. Participants were asked to examine each ECG and determine whether cardiac catheterization laboratory activation (CLA) was indicated, and to report their confidence in their decision making on an 11-point, numeric rating scale. The primary outcome measured was a pairwise difference in accuracy of CLA between daytime and overnight testing. RESULTS A total of 23 residents were enrolled in 2011 and 2012. Subjects demonstrated significant differences in multiple measures of sleepiness and fatigue during overnight periods. The median (interquartile range [IQR]) accuracy of CLA was not significantly different between daytime and overnight (70% [IQR, 50-80] versus 70% [IQR, 60-70], P  =  .82). There were no significant differences in the median number of overcalls (CLA when not a STEMI) and undercalls (no CLA when a STEMI was present; P  =  .57 and .37, respectively). Diagnostic confidence and confidence in CLA were not statistically different between daytime and overnight. CONCLUSIONS Despite a measurable degree of fatigue, senior EM residents experienced no decrease in their ability to accurately make CLA decisions based on ECG interpretation.

Student Advising Recommendations from the Council of Residency Directors Student Advising Task Force

Residency training in emergency medicine (EM) is highly sought after by U.S. allopathic medical school seniors; recently there has been a marked increase in the number of applications per student, raising costs for students and programs. Disseminating accurate advising information to applicants and programs could reduce excessive applying. Advising students applying to EM is a critical role for educators, clerkship directors, and program leaders (residency program director, associate and assistant program directors). A variety of advising resources is available through social media and individual organizations; however, currently there are no consensus recommendations that bridge these resources. The Council of Residency Directors (CORD) Student Advising Task Force (SATF) was initiated in 2013 to improve medical student advising. The SATF developed best-practice consensus recommendations and resources for student advising. Four documents (Medical Student Planner, EM Applicant’s Frequently Asked Questions, EM Applying Guide, and EM Medical Student Advisor Resource List) were developed and are intended to support prospective applicants and their advisors. The recommendations are designed for the mid-range EM applicant and will need to be tailored to students’ individual needs.

Blinded Evaluation of Combination Drug Therapy for Prolonged Ventricular Fibrillation Using a Swine Model of Sudden Cardiac Arrest.

ABSTRACT Despite experimental evidence supporting the use of resuscitation drugs in the treatment of sudden cardiac arrest (CA), there are no good human clinical data to support the decades-old practice of giving these medications during out-of-hospital CA resuscitation. We hypothesized that the lack of efficacy in clinical practice in ventricular fibrillation (VF) is the failure-based manner in which resuscitation drugs have historically been administered (one at a time interspersed with chest compressions and a defibrillation attempt, giving the next only if the previous one was ineffective). The aim of this study was to determine if giving and circulating a combination of commonly available, historically used resuscitation drugs together, prior to the first defibrillation attempt after prolonged VF, might improve short-term outcomes compared with the failure-based serial drug approach used in the past. We used a well-established swine model of sudden prolonged untreated VF. Animals were randomized to receive epinephrine (0.01 mg/kg), vasopressin (0.5 U/kg), amiodarone (4 mg/kg), and sodium bicarbonate (1.0 mEq/kg) in series (SERIES group [n = 53]) or a combination of epinephrine (0.01 mg/kg), vasopressin (0.5 U/kg), amiodarone (4 mg/kg), sodium bicarbonate (1.0 mEq/kg), and metoprolol (0.2 mg/kg) (COCKTAIL group) delivered in rapid succession at the beginning of the attempted resuscitation (n = 27). Data were analyzed descriptively. Baseline characteristics and chemistries between the two groups were the same. Termination of VF was statistically similar in the two groups: 88.7% (47/53) versus 85.2% (23/27) p = 0.66, with an adjusted relative risk ratio (RRR) of 0.94 (0.37, 1.15). However, ROSC was higher in the SERIES group (56.6% [30/53] versus 22.2% [6/27], adjusted RRR = 2.83; [1.16, 3.84] p = 0.029) as was 20-minute survival (52.8% [28/53] versus 18.5% [5/27], adjusted RRR = 3.15 [1.14, 4.54] p = 0.032). The combination of drugs studied, at these dosages, inexplicably worsened short-term outcomes after prolonged untreated VF.

An Observational Study to Assess Changes in Arterial Blood Gas Values During Untreated Porcine Ventricular Fibrillation

Abstract Background. Cardiocerebral resuscitation (CCR) is reportedly superior to cardiopulmonary resuscitation (CPR) for out-of-hospital cardiac arrest (OHCA) even though active ventilation is not initially provided. Understandably, concerns have been raised regarding the withholding of positive pressure ventilation (PPV) during CCR because of the longstanding belief that respiratory gas exchange is a critical action during resuscitation. Objective. In this observational study, we sought to quantify the effect of prolonged untreated ventricular fibrillation (VF) on arterial pH, partial pressure of carbon dioxide (pCO2), and partial pressure of oxygen (pO2) values in a swine model of witnessed cardiac arrest to begin exploring the validity of these concerns. Methods. Both included studies were approved by the institutional animal care and use committee (IACUC). Eighty-three animals (25–35 kg) were instrumented under general anesthesia. Baseline characteristics were recorded. An arterial blood gas (ABG) sample was drawn from each animal via femoral catheter just prior to electrical induction of VF. After 8 minutes of untreated VF in one study (study 1 [n = 30]) and 10 minutes of untreated VF in the other study (study 2 [n = 53]), a second ABG sample was drawn. All samples were processed immediately using an i-STAT portable whole blood analyzer. Baseline characteristics of animals in the two studies were assessed using descriptive statistics. For the second ABG sample in each study, the mean pH, pCO2, and pO2 values, with 95% confidence intervals (95% CIs), were determined. The paired ABG results for each animal were then compared and the average pH, pCO2, and pO2 proportions, with 95% CIs, for each study were calculated. Results. The baseline characteristics of the animals in the two studies were similar. After 8 and 10 minutes of untreated VF cardiac arrest, the pH values were 7.35 (95% CI = 7.32, 7.37) and 7.37 (95% CI = 7.36, 7.38), the pCO2 increased to 44.1 mmHg (95% CI = 41.1, 47.1) and 52.7 mmHg (95% CI = 51.0, 54.4), and the pO2 decreased to 44.8 mmHg (95% CI = 42.2, 47.4) and 45.5 mmHg (95% CI = 43.3, 47.6), respectively. Conclusions. Using our swine model of witnessed cardiac arrest with prolonged untreated VF, the arterial pH remained essentially unchanged and the pCO2 increased to 1.42 times baseline after 10 minutes, while almost half of the initial O2 concentration in the blood at the beginning of resuscitation remained.