Prehospital Hypotension and Mortality, Neuromuscular Blockade and RSI Success, Intubation Experience

Prehospital Hypotension and Mortality

Shapiro NI, Kociszewski C, Harrison T, et al. Isolated prehospital hypotension after traumatic injuries: A predictor of mortality? J Emerg Med 25(2):175-9, Aug. 2003.

Abstract: In patients with traumatic injuries, prehospital hypotension that resolves by emergency department arrival is of uncertain significance. [The authors] examined the impact of prehospital hypotension (PH) in normotensive ED patients with traumatic injuries on predicting mortality and chest/abdominal operative intervention. A retrospective cohort study of consecutive patients undergoing helicopter transport to two trauma centers between 1993-97 was conducted. Outcomes were mortality and chest or abdominal operative intervention. Of 545 scene transports, 55 patients (10.1%) were hypotensive on ED arrival, leaving 490 who were normotensive. Of those, 35 (7%) had PH, and 455 (93%) had no PH. Multiple logistic regression showed the PH group to have a relative risk for death of 4.4 (95% CI: 1.2-16.6, p < 0.03) and for chest or abdominal operative intervention of 2.9 (1.1-7.6, p < 0.03). In this study of normotensive trauma center patients, prehospital hypotension was associated with increased risk of mortality and significant chest or abdominal injury.

Comment: This is a frequent occurrence in the care of injured patients. The first or second field BP is low, but with a small amount of IV fluids-or even none-it returns to normal. This study shows that hypotension in the field, even if it resolves by the time the patient arrives in the ED, is a predictor of serious injury. Those patients with hypotension that resolved were three times more likely to need chest or abdominal surgery and four times more likely to die than those who were never hypotensive. Trauma protocols should recognize the predictive importance of hypotension, even if it is temporary.

Neuromuscular Blockade and RSI Success

Davis DP, Ochs M, Hoyt DB, et al. Paramedic-administered neuromuscular blockade improves prehospital intubation success in severely head-injured patients. J Trauma 55(4):713-9, Oct. 2003.

Abstract: The purpose of this study was to evaluate the effect of paramedic-administered neuromuscular blocking agents as part of a rapid-sequence intubation (RSI) protocol on successful intubation of severely head-injured patients in a large, urban prehospital system. Methods-Adult head-injured patients were prospectively enrolled over one year using these inclusion criteria: Glasgow Coma Scale (GCS) score of 3-8; transport time greater than 10 minutes; and inability to intubate without RSI. Midazolam and succinylcholine were administered before laryngoscopy; rocuronium was given after tube placement was confirmed using capnometry, syringe aspiration and pulse oximetry. The Combitube was used as a salvage airway device. All adult trauma victims with a GCS score of 3-8 during the first 12 months of the study were identified as the trial cohort, and from the preceding 12 months as the control cohort. The cohorts were compared with regard to demographic data, mechanism of injury, initial vital signs and GCS scores. The primary outcome measure was intubation success, defined as insertion of either an endotracheal tube or a Combitube, with patients stratified by GCS score. Results-The trial cohort (n=249) and control cohort (n=189) were similar with regard to demographic data, mechanism of injury and initial vital signs and GCS scores. Intubation success rates increased significantly during the trial period for all patients and when stratified into a GCS score of 3 and a GCS score of 4-8. The percentage of patients intubated without neuromuscular blocking agents actually increased during the trial period. Although the number of intubations by helicopter flight crews decreased during the trial, the overall use of aeromedical resources did not change. Conclusion-Paramedic-administered neuromuscular blockade as part of an RSI protocol improves intubation success in a large, urban prehospital system.

Comment: I included this study to point out how easy it is to be misled by conclusions, especially in abstracts. The authors here accurately conclude that intubation success rates for patients with head injuries and GCS scores of 8 or less improve when paramedics use RSI. The reader is left with the impression that an RSI program will benefit these patients. However, earlier this year, the same researchers reported that using RSI actually increased mortality in these same patients. So, although this study shows that the RSI patients were more likely to be intubated, the earlier study concluded they were less likely to survive! It is important to understand that each individual study must be interpreted in the context of our entire body of medical knowledge, and that decisions must be made using all available evidence.

Intubation Experience

Garza AG, Gratton MC, Coontz D, et al. Effect of paramedic experience on orotracheal intubation success rates. J Emerg Med 25(3):251-6, Oct. 2003.

Abstract: This study's objective was to determine the effect of paramedic experience on orotracheal intubation success in prehospital adult nontraumatic cardiac arrest patients. This retrospective study analyzed all attempted intubations of prehospital adult nontraumatic cardiac arrest patients between January 1, 1997 and April 30, 1997 in an all-ALS urban service. Variables included months of experience, number of patients in whom intubation was attempted, number of intubation attempts, success per attempt and success per patient. Ninety-eight paramedics performed 909 intubations on 1,066 cardiac arrest patients, yielding an intubation success rate of 85.3%. The median months of experience was 59.5 (range 5-223). The median number of patients per paramedic in whom intubation was attempted was 10 (range 1-36). The mean intubation success rate per paramedic was 80.6% (+/- 22.4, 95% CI: 76.1-85.1). There was significant correlation between the total number of patients in whom intubation was attempted and the intubation success rate (p < .001, R=0.32). There was no correlation between months of experience and intubation success rate. In conclusion, the number of patients per paramedic in whom intubation was attempted significantly correlated with the intubation success rate. Months of experience per paramedic had no significant correlation.

Comment: The relationship of regular performance of skills and competence is a topic that is gathering more attention throughout the practice of medicine. A number of studies have shown an association between the volume of procedures performed and the outcome of patients: The more a hospital or physician does something, the better it/he/she is at it. This study nicely demonstrates that those paramedics who had the opportunity to perform the skill more frequently-not those who had more months of experience-were more likely to successfully intubate. Initial training and years of experience are not adequate measures of a paramedic's ongoing competence; it takes a regular opportunity to perform skills to remain competent. EMS systems need to take this into consideration when evaluating their numbers of paramedics-an increased number will mean fewer opportunities for each-and their ongoing skills performance program.