Juan A. March

Decay in Quality of Closed-Chest Compressions Over Time

STUDY OBJECTIVE To characterize fatigue-induced deterioration in the adequacy of closed-chest compressions performed over a period of 5 minutes and to determine whether CPR providers can recognize the effects of fatigue on compression adequacy. DESIGN Prospective evaluation of study subjects performing closed-chest compressions on an electronic mannequin that assesses compression placement and depth. SETTING Major resuscitation room in rural university hospital emergency department. PARTICIPANTS Eleven experienced nursing assistants who regularly provide CPR in the ED. RESULTS Each study participant performed 5 minutes of closed-chest compressions. Compression adequacy (for placement and depth) was assessed with the mannequin and reported on an attached monitor out of view of the study subjects. Subjects were asked to verbally indicate the point during their 5-minute compression period at which they felt too fatigued to provide effective compressions (arbitrarily defined as a minimum of 90% of all compressions being judged correct by the mannequin). We used one-way repeated-measures ANOVA and regression analysis to determine whether compression adequacy diminished over time. ANOVA was also used to determine whether the total compressions performed per minute diminished over time. The percentage of correct chest compressions decreased significantly after 1 minute of compressions (P = .0001). We found 92.9% of compressions performed during minute 1 to be correct. The percentages for minutes 2 through 5 were as follows: 67.1%, 39.2%, 31.2%, and 18.0%. Regression analysis revealed a decrement in compression adequacy of 18.6% per minute after the first minute of compressions. The number of total compressions attempted per minute did not decrease (P = .98). Study subjects did not accurately identify the point during their 5-minute sessions at which their fatigue caused compressions to become impaired. Whereas mean compression adequacy declined below 90% after only 1 minute, the time of indicated fatigue was 253 +/- 40 seconds (mean +/- SD). CONCLUSION Although compression rate was maintained over time, chest compression quality declined significantly over the study period. Because CPR providers could not recognize their inability to provide proper compressions, cardiac arrest team leaders should carefully monitor compression adequacy during CPR to assure maximally effective care for patients receiving CPR.

Automated external defibrillation by very young, untrained children

For patients with sudden cardiac death (SCD), the time interval to defibrillation is the main determinant of survival. As such, the American Heart Association has attempted to promote public-access defibrillation (PAD). Previous studies have shown that automated external defibrillators (AEDs) can be used successfully by untrained adults. Objective: To determine whether very young, untrained children could use AEDs. Methods: Third-grade students from an elementary school participated in this study representing a convenience sample of volunteers. They were given no formal training, but were shown how to peel off the backing from the electrode pads, like a sticker. Students were then given a mock code situation using a training manikin. The time to delivery of first shock was recorded. Students were then trained during a 2-minute review of the process, one on one with an instructor, and the study was then repeated. Data were analyzed using a paired Students t-test comparing pre- and post-training. Results: Thirty-one children participated in the study, with a median age of 9 years. For untrained children, the mean time for delivery of the first shock was 59.3 ± 13.6 seconds, 95% CI = 54.3 to 64.3. Following training, the mean time for delivery of the first shock was 35.2 ± 6.0 seconds, 95% CI = 33.0 to 37.4, p = 0.001. Conclusion: Although this study suggests that even very young, untrained children can successfully perform automated external defibrillation, training does significantly decrease the time to delivery of first shock.

Changes in physical examination caused by use of spinal immobilization.

The standard of care for patients following blunt trauma includes midline palpation of vertebrae to rule out fractures. Previous studies have demonstrated that spinal immobilization does cause discomfort. Objective. To determine whether spinal immobilization causes changes in physical exam findings over time. Methods. This was a single-blinded, prospective study at a tertiary care university teaching hospital. Twenty healthy volunteers without previous back pain or injuries, 13 male and seven female, were fully immobilized for one hour, with a cervical collar and strapped to a long wooden backboard. Midline palpation of vertebrae to illicit pain was performed at 10-minute intervals. In addition, the participants were asked to rate neck and back pain on a scale from 1 to 10 (1 for no pain, and 10 for unbearable pain), to see whether subjective pain from immobilization correlated with tenderness to palpation. Results. Three patients had point tenderness of cervical vertebrae within 40 minutes. Five patients developed point tenderness of vertebrae by 60 minutes. Eighteen of 20 participants complained of increasing discomfort over time. The median initial pain scale was 1 (range 1-1), in contrast to 4 (range 1-9) at 60 minutes, p < 0.05. Conclusion. This study shows that over time, standard immobilization causes a false-positive exam for midline vertebral tenderness. In order to reduce this high false-positive rate for midline vertebral tenderness, the authors recommend that, initially on arrival to the emergency department, immediate evaluation occur of all immobilized patients. Furthermore, backboards should be modified to reduce patient discomfort to prevent the iatrogenically induced midline vertebral tenderness, thereby reducing subsequent false-positive examinations.

Utilization of a pressure-sensing monitor to improve in-flight chest compressions

Previous research at the Division of Air Medical Services at East Carolina University School of Medicine has demonstrated impairment of chest compression efficacy in the setting of an airborne BO-105 helicopter. This study was undertaken to determine whether in-flight compression efficacy could be improved with utilization of a pressure-sensing monitor providing real-time feedback during cardiopulmonary resuscitation (CPR). Ten flight nurses each performed two minutes of in-flight chest compressions on a mannequin that electronically assessed compression depth and hand placement. The session was then repeated using the pressure-sensing device. The mean proportion of correct compressions (95.7 +/- 3.2%) achieved with utilization of the pressure-sensing monitor was significantly higher (P < .01) than the corresponding proportion for the control group (33.4 +/- 12.1%). This study demonstrated that the difficulties of performing effective in-flight chest compressions are largely overcome with utilization of a pressure-sensing device providing real-time feedback on compression efficacy.

Motor vehicle crash fatalities among Hispanics in rural North Carolina

OBJECTIVES Deaths from motor vehicle crashes (MVCs) have decreased significantly over the past three decades. Unfortunately, few data have been collected regarding death rates for MVCs in minority populations. The purpose of this study was to compare the death rate of whites versus Hispanics for MVCs in a rural environment. METHODS This study examined one rural county in North Carolina from January 1, 1999, to December 31, 1999. A retrospective cohort study was performed using the North Carolina State Highway Patrol computerized database of MVCs. Data regarding the total number of MVCs, fatalities, alcohol-related deaths, seatbelt usage, and cause of the collision were analyzed for both whites and Hispanics. Census information regarding population in this region also was obtained from the U.S. Bureau of Census. Data were analyzed using a chi-square test, with an alpha value of 0.05 used to establish statistical significance. RESULTS During the study period, whites were involved in 2,689 MVCs, compared with 158 MVCs for Hispanics. Whites were involved in ten fatal MVCs, compared with seven fatal MVCs involving Hispanics. The percent of fatal MVCs for whites was 0.3%, or 10 deaths per 2,689 MVCs. In contrast, the percent of fatal MVCs for Hispanics was 4.4%, or 7 deaths per 158 MVCs; odds ratio (OR) = 12.4, 95% CI = 4.7 to 33.1. The 2000 Census Report for Pitt County noted a white population of 81,613 and a Hispanic population of 4,216. Based on these population data, the death rate for MVCs per 100,000 population was 12.3 for whites versus 166.0 for Hispanics, OR = 13.6, 95% CI = 5.2 to 35.6. Although the cause for this disparity was not determined, previous studies suggest that alcohol and decreased seatbelt usage are contributing factors. CONCLUSIONS In this study, the death rates among Hispanics for rural MVCs were significantly higher than for whites. The causes of this disparity are not clear but are important to define. Only by understanding this disparity can we begin to develop appropriate interventions that may prevent these deaths.

Does Ambulance Crew Size Affect On-Scene Time or Number of Prehospital Interventions?

INTRODUCTION While large cities typically staff ambulances with two emergency medical services (EMS) professionals, some EMS agencies use three people for ambulance crews. The Greenville, North Carolina, EMS agency converted from three-person to two-person EMS crews in July 1993. There are no published reports investigating the best crew size for out-of-hospital emergency care. HYPOTHESIS Two-person EMS crews perform the same number and types of interventions as three-person EMS crews. Two-person EMS crews do not have longer on-scene times than do three-person EMS crews. METHODS Data for the two most common advanced life support calls in this system--seizures and chest pains--were collected for the months of June and August 1993. Three-person EMS crews responded to both types of calls in June. In August, two-person EMS crews responded to seizure calls; two-person EMS crews accompanied by a fire department engine (pumper) with additional manpower responded to chest pain calls. The frequency of specific interventions, number of total interventions, and scene times for the August calls were compared to their historical control groups, the June calls. RESULTS One hundred twenty-six patient contacts were included in the study. There were no significant differences in total number or types of procedures performed for the two patient groups. Mean on-scene time for patients with seizures was 11.0 +/- 4.2 minutes for three-person crews and 19.4 +/- 8.3 minutes for two-person crews (p < 0.001). Mean on-scene time for patients with chest pain was 13.6 +/- 4.9 minutes for three-person crews, and 15.4 +/- 3.2 minutes for two-person crews assisted by fire department personnel (p > 0.05). CONCLUSION Two-person EMS crews perform the same number of procedures as do three-person EMS crews. However, without the assistance of additional responders, two-person EMS crews may have statistically significantly longer on-scene times than three-person EMS crews.

A breathing manikin model for teaching nasotracheal intubation to EMS professionals.

OBJECTIVE The widespread use of orotracheal intubation with rapid-sequence induction has made it difficult for emergency medical services (EMS) professionals to gain experience in nasotracheal intubation (NTI) in a controlled and supervised setting. The purpose of this study was to determine whether a training session on NTI with a breathing manikin can be used to improve the self-assessed skill level and comfort of EMS professionals. METHODS A prospective trial was conducted with a convenience sample of 33 EMS professionals, previously trained in NTI techniques. For the training session, a Laerdal airway manikin was modified by replacing the lungs with self-inflating resuscitation bag. The bag could then be squeezed to simulate breathing, with an inspiratory and expiratory phase. Following didactic instruction, and with direct supervision, each participant practiced NTI using this breathing manikin. Each participant completed a questionnaire, both before and after the training session, to determine self-assessed comfort and skill level for both oral and nasal intubations (0 = lowest, 10 = highest). The pre- and postintervention scores were compared using the Wilcoxon signed-rank test, alpha = 0.01. RESULTS Following the training session, the comfort level for NTI by the participants increased significantly from a median value of 2 to 7 (p = 0.001). Furthermore, the self-assessed skill level for NTI following the training session increased significantly from a median value of 4 to 8 (p = 0.0001). As expected, there were no significant differences noted in self-assessed skill level for orotracheal intubation following the training session. However, there was statistically significant improvement in self-assessed comfort levels for orotracheal intubation after the skills laboratory, p = 0.0001. CONCLUSION For EMS professionals, a training session for NTI using a relatively inexpensive and easily assembled breathing manikin model increases both comfort and self-assessed skill level.

Comparison Of The I-Gel Supraglottic And King Laryngotracheal Airways In A Simulated Tactical Environment

Abstract Background: When working in a tactical environment there are several different airway management options that exist. One published manuscript suggests that when compared to endotracheal intubation, the King LT laryngotracheal airway (KA) device minimizes time to successful tube placement and minimizes exposure in a tactical environment. However, comparison of two different blind insertion supraglottic airway devices in a tactical environment has not been performed. This study compared the I-Gel airway (IGA) to the KA in a simulated tactical environment, to determine if one device is superior in minimizing exposure and minimizing time to successful tube placement. Methods: This prospective randomized cross over trial was performed using the same methods and tactical environment employed in a previously published study, which compared endotracheal intubation versus the KA in a tactical environment. The tactical environment was simulated with a one-foot vertical barrier. The participants were paramedic students who wore an Advanced Combat Helmet (ACH) and a ballistic vest (IIIA) during the study. Participants were then randomized to perform tactical airway management on an airway manikin with either the KA or the IGA, and then again using the alternate device. The participants performed a low military type crawl and remained in this low position during each tube placement. We evaluated the time to successful tube placement between the IGA and KA. During attempts, participants were videotaped to monitor their height exposure above the barrier. Following completion, participants were asked which airway device they preferred. Data was analyzed using Students t-test across the groups for time to ventilation and height of exposure. Results: In total 19 paramedic students who were already at the basic EMT level participated. Time to successful placement for the KA was 39.7 seconds (95%CI: 32.7–46.7) versus 14.4 seconds (95%CI: 12.0–16.9) for the IGA, p < 0.001. Maximum height exposure of the helmet above a one foot vertical barrier for the KA resulted in 1.42 inches of exposure (95%CI: 0.38–0.63) compared to the IGA with 1.42 inches, 95%CI:0.32–0.74, p = 0.99. On questioning 100% of the participants preferred the IGA device over the KA. Conclusion: In a simulated tactical environment placement of the IGA for airway management was faster than with the KA, but there was no difference in regard to exposure. Additionally, all the participants preferred using the IGA device over the KA.

Retention of cricothyrotomy skills by paramedics using a wire guided technique

Introduction Cricothyrotomy may be necessary for airway management when a patients airway cannot be maintained through standard techniques such as oral airway placement, blind insertion airway device, or endotracheal intubation. Wire‐guided cricothyrotomy is one of many techniques used to perform a cricothyrotomy. Although there is some controversy over which cricothyrotomy technique is superior, there is no published data regarding long term retention rates. The purpose of this study is to determine whether ground based paramedics can be taught and are able to retain the skills necessary to successfully perform a wire‐guided cricothyrotomy. Methods This retrospective study was performed in a suburban county with a population of 160,000 with 23,000 EMS calls per year. Participants were ground‐based paramedics who were taught wire‐guided cricothyrotomy as part of a standardized paramedic educational update program. After viewing an instructional video, the paramedics were shown each the steps of the procedure on a simulation model, using a low fidelity task trainer previously developed to train emergency medicine residents. Using a 16 step procedural checklist, participants were allowed open‐ended practice using the task trainer. Critical steps in the checklist were marked in bold lettering indicating automatic failure. Each paramedic was then individually supervised performing a minimum of 5 successful simulations. Retention was assessed using the same 16 step checklist 6 to 12 weeks following the initial training. Results A total of 55 paramedics completed both the initial training and reassessment during the time period studied. During the initial training phase 100% (55 of 55) of the paramedics were successful in performing all 16 steps of the wire‐guided cricothyrotomy. During the retention phase, 87.3% (48 of 55) of paramedics retained the skills necessary to successfully perform the wire‐guided cricothyrotomy. On the 16 step checklist, most steps were performed successfully by all the paramedics or missed by only 1 of the 55 paramedics. The step involving removal of the needle prior to advancing the airway device over the guide wire was missed by 34.5% (19 of 55) of the participants. This was not an automatic failure since most participants immediately self‐corrected and completed the procedure successfully. Conclusion Paramedics can be taught and can retain the skills necessary to successfully perform a wire‐guided cricothyrotomy on a simulator. Future research is necessary to determine if paramedics can successfully transfer these skills to real patients.

19. A Breathing Manikin Model for Teaching Nasotracheal Intubation to EMS Professionals

Purpose : The wide spread use of orotracheal intubation with rapid sequence induction has made it difficult for EMS professionals to gain experience in nasotracheal intubation (NTI) in a controlled supervised setting. The purpose of this study was to determine if a training session on NTI with a breathing manikin can be used to improve skill and comfort of EMS professionals. Methods : A prospective trial was conducted with a convenience sample of 16 emergency medical service professionals, previously trained in nasotracheal intubation techniques. For the training session a Laerdal airway manikin was modified by replacing the lungs with a bag-valve mask device, to simulate breathing with an inspiratory and expiratory phase. Following verbal instruction, and with direct supervision, each participant practiced NTI using the breathing manikin. Each participant completed a questionnaire, both before and after the training session, to determine self assessed comfort and skill level for both oral and nasal intubations (0 = lowest, 10 = highest). The pre and post intervention scores were compared using the Wilcoxon signed-rank test, £ = 0.01.