Recurrent VF; ETI After Traumatic Brain Injury; ED Estimates of Patients` Weights

Recurrent VF After Police/Fire Defibrillation

Hess EP, White RD. Recurrent ventricular fibrillation in out-of-hospital cardiac arrest after defibrillation by police and firefighters: Implications for automated external defibrillator users. Crit Care Med 32(9 Suppl.): S436--9, September 2004.

Abstract: This study was designed to determine the prevalence and frequency of recurrent ventricular fibrillation (VF) in patients defibrillated by police and firefighters only, and to determine its relation to survival. Patients--Individuals with witnessed VF arrest in the Rochester, MN, ambulance public service area who had defibrillatory shocks delivered by police and firefighters with return of spontaneous circulation with shocks only. Measurements and Main Results--Electrocardiograms were recovered from data cards in automated external defibrillators used by police (n=49) or firefighters (n=18) to deliver shocks from December 1996 through December 2003 in the Rochester area. Patients with witnessed VF arrest were identified for recurrent VF after initial shock success (first 1--3 shocks). Both police and firefighters deployed automated external defibrillators delivering nonescalating 150J biphasic truncated exponential waveform shocks. Among 67 patients, 30 (45%) survived to neurologically intact discharge. Twenty-nine patients (43%) regained spontaneous circulation with shocks only, and 25 of 29 (86%) survived. VF recurred in 35 of the 67 patients (52%) while being cared for by police or firefighters. Of these 35 patients, no relation was found between the prevalence or frequency of VF recurrence and survival. Conclusions--VF recurrence is frequent, variable in time of onset and unrelated to the performance of bystander CPR. The prevalence and frequency of VF recurrence are unpredictable and do not adversely affect survival. Thus, vigilance for recurrent VF is essential to ensure the survival of patients who are in the care of first responders, even after initial restoration of pulses with shocks.

Comment: This is a good reminder that good medical care does not end with the first procedure or medication that seems to make the patient improve. Patients who go into ventricular fibrillation and are successfully defibrillated are still at great danger of going back into VF--it occurred to over half of them in this group. This makes logical sense, since at that point we have not done anything to reverse the condition that caused them to go into VF in the first place. What makes this even more important is that the recurrence of VF, as long as it is treated promptly, does not reduce the likelihood of survival. Treatment protocols should emphasize the vigilant and continuous monitoring of post-defibrillation patients.

Out-of-Hospital ETI for Brain-Injured Patients

Wang HE, Peitzman AB, Cassidy LD, et al. Out-of-hospital endotracheal intubation and outcome after traumatic brain injury. Ann Emerg Med 44(5): 439--50, 2004.

Abstract: Previous studies disagree about the effect of out-of-hospital endotracheal intubation on traumatic brain injury. This study compares the effects of out-of-hospital endotracheal intubation versus emergency department (ED) endotracheal intubation on mortality and neurologic and functional outcome after severe traumatic brain injury. Methods--From the 2000--2002 Pennsylvania Trauma Outcome Study (a registry of all patients treated at trauma centers in the Commonwealth of Pennsylvania), adult patients with head/neck Abbreviated Injury Scale scores of 3 or greater and undergoing out-of-hospital endotracheal intubation or ED endotracheal intubation were included. Transferred patients were excluded. The primary outcome was death (on hospital discharge). The secondary outcomes were neurologic (good versus poor, inferred from discharge to home versus long-term care facility) and functional outcomes (determined from a Functional Impairment Score). The key exposure was endotracheal intubation (out-of-hospital endotracheal intubation versus ED endotracheal intubation). Using multivariate logistic regression, odds estimates for out-of-hospital endotracheal intubation were adjusted using age, sex, head/neck Abbreviated Injury Scale score, Injury Severity Score, mechanism of injury (penetrating versus blunt), admission systolic blood pressure, mode of transport (ground-only versus helicopter or helicopter-plus-ground) and the use of out-of-hospital neuromuscular blocking agents. A propensity score adjustment accounted for the potential effects of pre-existing conditions, in-hospital complications and social factors (drug and alcohol use, race and insurance coverage).

Results--There were 4,098 patients with head/neck Abbreviated Injury Scale scores of 3 or greater who received either out-of-hospital endotracheal intubation (n=1,797, 43.9%) or ED endotracheal intubation (n=2,301, 56.1%). Adjusted odds of death were higher for out-of-hospital endotracheal intubation than ED endotracheal intubation (odds ratio [OR] 3.99; 95% confidence interval [CI] 3.21--4.93). Out-of-hospital endotracheal intubation was associated with increased adjusted odds of poor neurologic outcome (OR 1.61; 95% CI 1.15--2.26), moderate or severe functional impairment (Functional Impairment Score 6--15; OR 1.92; 95% CI 1.40--2.64), and severe functional impairment (Functional Impairment Score 11--15; OR 1.80; 95% CI 1.29--2.52). Conclusion--Out-of-hospital endotracheal intubation was associated with adverse outcomes after severe traumatic brain injury. The implications for current clinical care remain undefined.

Comment: This is an important study that needs careful interpretation. First, it is another very valuable outcome study. As I've mentioned before, we need, in EMS, to move beyond the types of research that look at success rates and short-term patient improvements and begin to evaluate what we do on the basis of how it affects eventual patient outcomes. These are difficult and time-consuming studies, but ultimately much more valuable.

Here, the authors found that the prehospital practice of ET intubation in brain-injured patients did not only not improve outcome, but worsened it. The San Diego RSI trial had similar results. The authors accurately pointed out, though, that it would not be appropriate to conclude that prehospital ETI is always detrimental--only that the way it was done at that time seemed to worsen outcomes. Further research needs to be done to determine if improved training, indications for ETI or procedural changes may improve outcomes. At this time, though, the practice of prehospital ETI after brain injury does not appear to benefit the patient.

Errors in ED Weight Estimation

Hall WL, II, Larkin GL, Trujillo MJ, et al. Errors in weight estimation in the emergency department: Comparing performance by providers and patients. J Emerg Med 27(3): 219--24, October 2004.

Abstract: To examine biases in weight estimation by Emergency Department (ED) providers and patients, a convenience sample of ED providers (faculty, residents, interns, nurses, medical students, paramedics) and patients was studied. Providers (n=33), blinded to the study hypothesis and patient data, estimated their own weights as well as the weights of 11--20 patients each. An independent sample of patients (n=95) was used to assess biases in patients' estimation of their own weights. Data are represented as over, under or within +/- 5 kg, the dose tolerance standard for thrombolytics. Logistic regression analysis revealed that patients are almost nine times more likely to accurately estimate their own weights than providers; yet 22% of patients were unable to estimate their own weights within 5 kg. Of all providers, paramedics were significantly worse estimators of patient weights than other providers. Providers were no better at guessing their own weights than were patients. Though there was no systematic estimate bias by weight, experience level (except paramedic) or gender for providers, those providers under 30 years of age were significantly better estimators of patient weights than older providers. Although patient gender did not create a bias in provider estimation accuracy, providers were more likely to underestimate women's weights than men's. In conclusion, patient self-estimates of their weights are significantly better than estimates by providers. Inaccurate estimates by both groups could potentially contribute to medication dosing errors in the ED.

Comment: A number of medications are given in per-kilogram doses. We probably all would guess the conclusion of this study is correct, but often don't use this simple tool to estimate the patient's weight: Ask the patient. This study verified that the patient is considerably more accurate than any healthcare provider in estimating their own weight. EMS protocols should remind personnel to use their own estimates only if the patient cannot effectively communicate or estimate for them.