Keeping Up - Update 16
Rea TD et al. CPR with Chest Compression Alone or with Rescue Breathing. N Engl J Med July 2010;363:423-33.
Study Question: Which is better, for bystanders to do CPR with chest compressions only or CPR plus rescue breathing?
Results: In this multicenter, randomized controlled trial, 981 received dispatcher instructions for chest compressions (CC) alone, and 960 received CC plus rescue breathing (RB) instructions. The groups were well matched at randomization. For the primary outcome of survival to hospital discharge, there was no significant difference between CPR methods (12.5% CC vs. 11% CC+RB, p = 0.31) nor was there a difference in neurologically intact survival (14.4% CC vs. 11.5% CC+RB, p = 0.13). There was 2% crossover between CPR methods, with more moving from CC+RB to CC alone than vice versa. Also, though both groups were instructed to do CC, the CC alone group was more likely to have bystanders perform CC than those instructed to do both CC and RB (80.5% CC vs. 72.7% CC+RB, p<0.001). In predefined subgroup analysis, those with a cardiac cause of arrest had improved neurologically intact survival with CC alone (18.9% vs. 13.5%, p = 0.03).
Limitations: The fact that more bystanders randomized to CC alone actually did CC at all may have led to the trend toward improved survival. They would have needed almost twice as many patients for the difference in neurologically intact survival to show a statistically significant difference. A 15:2 compression to ventilation ratio was used; the current 30:2 ratio may have given a different outcome.
Take Home: CPR with CC alone is much simpler, less messy, and appears to have a slight advantage of CC+RB, especially in those with a cardiac cause of arrest.
Level of Evidence: 1
Svensson L et al. Compression-Only CPR or Standard CPR in Out-of-Hospital Cardiac Arrest. N Engl J Med July 2010;363(5):434-42.
Study Question: In witnessed arrest, is compression-only CPR better or worse than standard CPR?
Results: This prospective, Swedish study randomized 3,809 patients into compression-only CPR or standard CPR groups. Both groups received EMS dispatcher instructions as how to perform CPR. Data was available for 1,276 patients (33%). Primary outcome was 30-day survival and was 8.7% in the compression-only group and 7.0% in the standard CPR group (not statistically significant).
Limitations: There was significant chance of a type II error with this study (sample size too small to determine a difference), as this was underpowered for their initial and revised calculations. Large amounts of patients were excluded (2,532 patients) for various reasons. It would have been nice to analyze those excluded, because CPR was already started or the caller knew how to perform CPR (375 patients). Also, we do not know how well people followed the dispatcher instructions.
Take Home: Honestly, I just want bystanders on the chest and pushing. The only breaths they should take are for themselves as they are pushing.
Level of Evidence: 1
Kitamura T et al. Bystander-Initiated Rescue Breathing for Out-of-Hospital Cardiac Arrests of Noncardiac Origin. Circulation July 2010;122:293-9.
Study Question: What if arrest is from a non-cardiac etiology: standard CPR or compression only?
Results: This was a prospective, observational study from Japan's arrest registry that found > 43,000 patients with non-cardiac cause of arrest. Of these, about 60% had no bystander CPR; 7,474 had conventional CPR, and 8,878 had chest compression (CC) only CPR. The conventional CPR group had more survivors (1.8%) to hospital discharge and more neurologically intact survivors than CC only CPR.
Limitations: The overall survival rates, regardless of CPR type, were abysmal compared Rea et al covered earlier in the podcast, which had survival to discharge in non-cardiac cause of arrest 5-7%. Also, more people in the CC only group were in asystole on first rhythm check (59.7% CC vs. 59.4% conventional). EMS response times were slow, averaging about 11.5 minutes. This study had a high percentage classified as non-cardiac etiology, >45%, compared with 30% in the Rea study.
Take Home: This study agrees with the Rea and Svensson interventional trials we discussed today: if arrest is not from a cardiac etiology, do conventional CPR. But in undifferentiated arrest, the patient is more likely to have neurologically intact survival with chest compressions only.
Level of Evidence: 2
Kontos MC et al. Emergency physician-initiated cath lab activation reduces door to balloon times in ST-segment elevation myocardial infarction patients. Am J Emerg Med in press 2010;doi:10.1016/j.ajem.2010.03.025.
Study Question: How much better are door-to-balloon (D2B) and cardiac cath lab activation (CCL) times by utilizing recommendations from the ACC D2B project?
Results: This retrospective case series evaluated the D2B and CCL times after implementing three processes in a stepwise fashion: single call serves as a global page to activate, EP activation, and EP+EMS activation. 295 patients were analyzed. Times were better with EP and EMS activation, and a greater proportion of patients met the 90-minute D2B guidelines.
Limitations: Multiple processes were improved during this study, including upstream from the ED that surely helped the times. The study was observational at one tertiary academic center.
Take Home: In order to improve D2B and CCL times, work with your cardiology and EMS colleagues to develop protocols allowing prehospital activation and ED activation with a single phone call/paging system. Our job is to get them as quickly and safely as possible to the cath lab; the rest is left to the cardiologists.
Level of Evidence: 3
Amsterdam EA et al. Testing of Low-Risk Patients Presenting to the Emergency Department With Chest Pain: AHA Scientific Statement. Circulation August 2010;122:756-76.
Study Question: What is the current best evidence for the diagnostic tools we use in working up low risk chest pain patients?
- Determining "low risk" means patients have no coronary artery disease (CAD) or prolonged pain (<20 min) or they have a low clinical risk score (i.e. TIMI risk score), normal or near-normal ECG, and negative cardiac injury biomarkers.
- Chest pain units are useful in assessing low risk patients by utilizing serial ECG and serial cardiac biomarkers.
- An accelerated diagnostic protocol (ADP) takes into account history, exam, ECG, biomarkers, CXR, and often confirmatory testing.
- Confirmatory tests include the exercise treadmill test (ETT) with 70% sensitivity and 75% specificity. Adding to the ETT are myocardial perfusion imaging (MPI) and stress echocardiogram, with sensitivities of 86-87%. Radiation is the disadvantage of MPI, while echo has lower NPV (89-100%). Pain MPI and pain echo are less sensitive alternatives. Stress testing can be done within 72 hours if patients are low risk with no chest pain, normal ECG, and negative biomarkers.
- Coronary CTA is helpful if normal in a low risk patient but requires ionizing radiation and IV contrast and can only be done in select patients able to breath-hold and having slow heart rates. MRI is an emerging technology for this application.
- Elderly, diabetic, and patients with known CAD are at higher risk. For us in the ED, involve cardiology in the decision making.
- What about chest pain unit recidivism, occurring in 21-26%? In other words, what is the warranty period for a negative initial work up? Patients with normal stress MPI had 1.1% risk of cardiac event in 2-year follow up, but those with higher baseline risk had 1.4-1.8% rate of cardiac events.
Limitations: This is an AHA statement based on the authors' interpretation of the literature.
Take Home: In low risk patients, get a couple of ECGs and sets of cardiac injury markers and consider imaging for most of them.
Level of Evidence: This is a literature review.
Dmello D et al. Outcomes of Etomidate in Severe Sepsis and Septic Shock. Chest in press 2010;doi10.1378/chest.10-0790.
Study Question: Is etomidate use for rapid sequence intubation (RSI) harmful in patients with sepsis?
Results: 113/224 patients in this retrospective cohort of patients with severe sepsis or septic shock received etomidate for RSI. There was no difference in in-hospital mortality, vasopressor use, ICU length of stay, or ventilator days between etomidate and non-etomidate cohorts. More patients in the etomidate group received steroids.
Limitations: This was retrospective and not interventional.
Take Home: Until etomidate is shown to be associated with adverse outcomes in a large, interventional study, it should be considered safe to use for RSI.
Level of Evidence: 3
Runeson B et al. Method of attempted suicide as predictor of subsequent successful suicide: national long term cohort study. BMJ July 2010;340:c3222.
Study Question: Are all suicide attempts the same? What is the association between attempt method and subsequent suicide?
Results: This Swedish cohort study followed 48,649 patients admitted between 1973 and 1982 for a suicide attempt. Patient follow-up ranged from 21 to 31 years. Of the initial 48,649 patients, 5,740 (11%) patients committed suicide during the follow-up period. Using poisoning as the reference, the greatest risk (6.2) was with initial attempt by hanging/strangulation/suffocation. Drowning, firearms, and jumping from heights had hazard ratios greater than 3. Cutting was equivalent to poisoning. People tended to use the same method as their initial one and tended to be successful within the 1st year when more violent methods were employed.
Limitations: The initial cohort included only patients admitted to the hospital. Poisoning was used as the reference, but it was also the most common method (initial 77% men/90% women and successful 69% men/82% women).
Take Home: Not all suicide attempts are equal - take the method into account.
Level of Evidence: 2
Cotton BA et al. Multicenter Validation of a Simplified Score to Predict Massive Transfusion in Trauma. J Trauma July 2010;69: S33-39.
Study Question: Can we predict who may need mass transfusion (i.e. 10 units PRBCs/24 hours) with simple, readily available variables?
Results: This was a retrospective study using the trauma registries from three institutions and applying the following variables to predict mass transfusion: penetrating mechanism (no = 0/yes = 1), ED systolic blood pressure 120 beats/minute (no = 0/yes = 1), and positive FAST (no = 0/yes = 1). For a score >=2, the sensitivity ranged from 76-90%, and area under the ROC curve (overall diagnostic accuracy) was 0.83-0.90.
Limitations: This was a retrospective study and relied on accuracy of the FAST exam.
Take Home: If your trauma patient has 2 or more of the above variables, be ready to activate mass transfusion protocols. More importantly for the ED, have a low threshold to transfuse uncrossmatched "trauma blood" in the ED trauma bay in such patients.
Level of Evidence: 2
Walls RM et al. A new maneuver for endotracheal tube insertion during difficult Glidescope intubation. J Emerg Med July 2010;39(1):86-8.
Study Question: Not a study but rather a technique paper.
Results: Failures with video laryngoscopes are rare; however this case report presents a failure and a technique to overcome that failure. The difficulty in passing the tube was the steep posterior course of the trachea in relation to the glottic opening. To overcome this, the endotracheal tube was rotated 180 degrees after passing the vocal cords. Now the sharp angle of the tube matched the sharp, posterior angle of the trachea and the tube was passed easily.
Limitations: None, technique only.
Take Home: Failures do occur with the Glidescope based on difficulty passing the tube. Several tricks have been described, but this one worked because the authors actually assessed the anatomy and developed a plan to match the anatomy - the true learning point from this paper. Always think to yourself, "Why won't this tube pass?" Then develop a plan to pass the tube.
Level of Evidence: 4
Komatsu R et al. Airway Scope and Macintosh Laryngoscope for Tracheal Intubation in Patients Lying on the Ground. Anesth Analg August 2010;111:427-31.
Study Question: Is an Airway Scope (AWS) or Mac 3 better when intubating a patient lying on the ground?
Results: 100 patients were randomized 50:50 to intubation with one or the other device with the intubator on a table at the level of the patient's head to simulate intubation on the ground (left lateral decubitus at the head with a Mac and kneeling with the AWS). There was 100% success with the Mac 3 and 98% success with the AWS; the AWS was 17 seconds faster even though it required more attempts.
Limitations: Generalizing this to the prehospital setting in patients with a full stomach, bloody airways, and high ambient light conditions would be difficult.
Take Home: Intubation at ground level is difficult. Use of an Airway Scope may make it faster.
Level of Evidence: 1
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