International Prehospital Medicine Institute Literature Review, October 2021

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Vol. 4.2

1. Automated external defibrillators delivered by drones to patients with suspected out-of-hospital cardiac arrest. Schierbeck S, Hollenberg J, Nord A, et al. European Heart J. 2021; Published on-line ahead of print. Full text available at: https://academic.oup.com/eurheartj/advance-article/doi/10.1093/eurheartj/ehab498/6358076.

2. An Eastern Association for the Surgery of Trauma multicenter trial examining prehospital procedures in penetrating trauma patients. Taghavi S, Maher Z, Goldberg AJ, et al.  J Trauma Acute Care Surg. 2021;91:130-140.

3. Ultrasound Use in the Prehospital Setting for Trauma: A Systematic Review. Mercer CB, Ball M, Cash RE, Rivard MK, Chrzan K, Panchal AR. Prehosp Emerg Care, 2021;25:566-582

4. Pilot randomized trial of pre-hospital advanced therapies for the control of hemorrhage (PATCH) using pelvic binders. Pierrie SN, Seymour RB, Wally MK, et al. Amer J Emerg Med 2021;42:43–48.


Previous: International Prehospital Medicine Institute Literature Review, September 2021


1. Automated external defibrillators delivered by drones to patients with suspected out-of-hospital cardiac arrest. Schierbeck S, Hollenberg J, Nord A, et al. European Heart J. 2021; Published on-line ahead of print. Full text available at: https://academic.oup.com/eurheartj/advance-article/doi/10.1093/eurheartj/ehab498/6358076.

The use of automated external defibrillators (AED) by the lay public has long been accepted as part of the management of Out of Hospital Cardiac Arrest (OHCA). It is commonplace to see AED’s prepositioned in areas of public access such as airports, shopping malls and public schools and buildings. However, the most common place for a cardiac arrest to take place is in the home. The authors of this prospective clinical study propose to demonstrate the feasibility of deployment of AED’s to the scene of an OHCA via the use of a drone delivery system in a real world environment.

The study period was from June 1 to September 30, 2020. The study took place in Sweden’s second largest city with a population of approximately 80,000. The primary endpoint of the study was the delivery of the AED to the scene of the OHCA. Flights were conducted between the hours of 0800 and 220 when the controlled airspace from the local airport was open for access.  Prior to the study period multiple test flights were conducted, followed by responses to actual calls. Exclusion criteria included limitations of flight paths (no-fly zones), high rise buildings greater than 5 stories, and weather-related issues. The drones used were DJI Matrice 600 Pro hexacopter drones modified for AED delivery and were operated remotely from hangars controlled by the drone operator in the mission control center.  

A total of sixty-two (62) test flights were conducted along with 12 actual responses to OHCA patients. Of the 12 actual OHCA responses, 11 of the 12 had a successful delivery of the AED. In 7 of the 11 successful deliveries (64%), delivery of the AED occurred prior to ambulance arrival. The median time of delivery of the AED prior to EMS arrival was 1.54 minutes. The mean distance to the delivery site to the scene of the OHCA was less than 10 meters. The most important limiting factors to drone use were rain and wind.

The authors conclude that “In this pilot study, we have shown that AEDs can be carried by drones to real-life cases of OHCA with a successful AED delivery rate of 92%. There was a time benefit as compared to EMS in cases where the drone arrived first. However, further improvements are needed to increase dispatch rate and time benefits.”

There are a number of limitations to this study. While the authors showed that an AED can be delivered prior to ambulance arrival using a drone, none of the patients included in the study had an AED applied prior to ambulance arrival (0/11).  Demonstrating that equipment can be delivered to the scene is only the first step in the management of OHCA. The deployment of the AED after delivery is the other key step. Optimal real world implementation requires a public education component of this type of program. In addition, demonstration that better patient outcomes resulted is also necessary to justify the implementation and maintenance costs.  Results could also differ in a more rural area where ambulance/first responder arrival times may be greater than that of a more densely populated urban environment. The study did not attempt to measure the amount of time needed from the time of drone landing until the AED could be accessed by a bystander, brought to the victim and applied. This is particularly important if the OHCA occurs in a high rise building. Lastly, it remains to be determined whether outcomes are improved or worsened when there is only one caller who may have to interrupt CPR to retrieve the AED.

The use of drones in medicine has great potential and has expanded dramatically over the past few years.  Pilot studies such as this are the first step to demonstrating where exactly drones will have their greatest impact.

2. An Eastern Association for the Surgery of Trauma multicenter trial examining prehospital procedures in penetrating trauma patients. Taghavi S, Maher Z, Goldberg AJ, et al.  J Trauma Acute Care Surg. 2021;91:130-140.

Prehospital procedures continue to be performed on patients with penetrating trauma despite growing evidence that they do not improve survival and may be harmful. Procedures carried out prior to transport increase scene time and delay transport to definitive care, while procedures performed in route to the hospital may still not be beneficial.

The authors conducted a multicenter, prospective, observational trial of adults with penetrating trauma to the torso and/or extremities proximal to the knee and elbow. Data collected included patient demographics, type of transport (private vehicle, police vehicle, BLS ambulance, or ALS ambulance), prehospital interventions, vital signs, recesses requirements, and mortality. Specific prehospital interventions examined included: IV access, intraosseous access, fluid administration, bladder catheterization, endotracheal intubation, cervical spine mobilization, pleural decompression, tourniquet placement, pressure dressing application, cricothyrotomy, and pelvic stabilization. Patients were dichotomized into two groups based on whether or not they received a prehospital intervention. The primary outcome was in-hospital mortality. The secondary outcome of interest was the incidence of in-hospital complications.

A total of 2,284 patients were included in the study. The method of transport from most to least frequent was: EMS ALS (62.5%), private vehicle (17.2%), police (13.7%), and EMS BLS (6.7%). Overall, 60.7% of patients received at least one prehospital intervention. The most performed procedure was IV access (87.4%) followed by fluid resuscitation (48.1%) and application of a pressure dressing (29.5%). If the patient received IV fluid it was nearly always crystalloid (98.8%). Endotracheal intubation was performed in 7.1% of patients. No patient received bladder catheterization or a cricothyrotomy in this study cohort. All prehospital procedures were more commonly performed on scene, except for fluid administration.

Intubation, intraosseous access, fluid resuscitation, cervical spine mobilization, and pleural decompression were all significantly associated with increased odds of mortality. Application of pressure dressings was shown to decrease the odds of mortality, as did IV access. Interestingly, tourniquet application was not found to be associated with improved mortality. Receipt of any prehospital procedure increased the odds of mortality by 38% (OR, 1.38). Patients who received any prehospital procedure had an overall longer length of stay in the hospital compared to those who had no prehospital procedures. Those who received a prehospital procedure were more likely to develop acute respiratory distress syndrome, venous thromboembolism, and urinary tract infections.

As prior studies have demonstrated, prehospital fluid resuscitation increased mortality. The authors examined the volume of prehospital crystalloid use in 250-mL increments. Patients who received volumes of less than 250 mL, 251 to 500 mL, and 501 to 750 mL did not have a significant association with mortality when compared to those who received no crystalloid. However, administration of crystalloid volumes greater than 750 mL was associated with increased mortality (OR, 3.10).

The method of transport did not affect survival. After controlling for confounders, patients transported by a BLS ambulance, private vehicle, or police car had a similar rate of survival compared to those transported by an ALS ambulance.

Limitations of the study included an inherent selection bias, as patients who received prehospital procedures, particularly intubation, were usually more severely injured and therefore less likely to survive in the first place. The exact influence of prehospital procedures on transport time could not be determined. Additionally, accurate transport times are unavailable for private vehicle and police car transport. The setting for the study was urban penetrating trauma and may not be applicable to other settings.

In conclusion, the authors have shown in this multicenter trial that most prehospital procedures for penetrating trauma in the urban environment did not improve survival and may in fact be harmful. IV access, if performed while in route to the hospital, may be beneficial. However, prehospital fluid resuscitation did not improve survival and volumes greater than 750 mL were harmful. Finally, blood volume preserving procedures such as tourniquets and pressure dressings were not harmful but were also not shown to be definitively helpful in this environment where transport times are short. The authors did not recommend against the use of tourniquets and pressure dressings, however. Hopefully this article will allow for critical evaluation and potential modification of national and local guidelines for the care of the prehospital penetrating trauma patient.

3. Ultrasound Use in the Prehospital Setting for Trauma: A Systematic Review. Mercer CB, Ball M, Cash RE, Rivard MK, Chrzan K, Panchal AR. Prehosp Emerg Care, 2021;25:566-582.

The use of ultrasound in the field has gradually been increasing however its role has not been clearly defined. While there is no question as to its feasibility in the prehospital setting, its impact, particularly on the prehospital management of trauma, has yet to be determined.

The authors conducted a systematic review of the literature using MEDLINE/PUBMED, EBSCOhost, Cochrane Library and Embase medical literature libraries. The selection criteria were based on studies that specifically addressed ultrasound used in the field to assess trauma patients. In all, 16 studies were identified that met criteria representing 3,317 patients.

There was a significant geographic disparity with only five of the sixteen studies conducted in the United States and system disparity with ten of the studies which included helicopter transport teams. In the 16 studies reviewed, seven different screening protocols were used. These included: FAST (focused assessment with sonography in trauma), EFAST (extended focused assessment with sonography in trauma), Phase (prehospital application of sonography in emergencies, Ultrasound-guided peripheral nerve blocks, symptom guided POCUS, EFAST with an electrocardiogram, and PREP (polytrauma rapid echo-evaluation program).

In terms of the ultrasound operator, only one study looked at EMS providers as the operators, five studies described “mixed” practitioners (physicians, nurses, and EMS personnel) and ten studies had physicians performing the ultrasounds. In the one study that used teams made up of EMS professionals alone, the providers received six hours of ultrasound training. The EMS personnel formed an impression that was over-read by emergency physicians expert in sonography. The study showed 100% agreement between the EMS personnel readings and the over-read by the emergency physicians but only 6 of the 84 had positive findings, thus limiting the impact of the strength of their performance.

In the 10 studies where physicians performed the ultrasounds on 2,076 patients, they noted a large disparity in sensitivity for accuracy which affected treatment and transport decisions. Only five of the studies reported on diagnostic accuracy and only six of the 10 looked at impact on transport decisions. Only 3 of these studies reported findings in both diagnostic accuracy and transport decisions.

The analysis of the five studies with mixed practitioner teams (doctors, nurses and EMS) revealed three of them reporting diagnostic accuracy and one study which reported treatment and transport decisions. Prehospital ultrasound impacted treatment in 21% of the patients, provided additional information to the hospital in 4.6% of the patients and changed the choice of destination in 22% of the cases.

They identified risk bias with eight of the sixteen studies with acceptable quality. No studies met the high quality level. Along with the fact that most trauma studies are non-randomized observations, they rated the quality of the evidence presented in these studies as low.

The limitations of this review include the fact that a meta-analysis was not possible due to the heterogeneity of the studies. Also, as stated previously, due to the observational nature of most of these studies, the overall quality of the evidence is low.

Ultrasound is widely used in emergency departments for the evaluation and management of acute trauma. The use of ultrasound in the prehospital setting has the potential improve the prehospital management as well however, additional large scale evidence based studies are needed to prove that benefit. It is significant to note that most of the available data comes from physician based EMS services and the evidence is of low quality. Randomized studies comparing prehospital trauma patients evaluated in the field with ultrasound to those where ultrasound is not used are required to determine if decision-making and destination are truly changed. In addition, studies of prehospital ultrasound performed by non-physician EMS professionals are needed.

4. Pilot randomized trial of pre-hospital advanced therapies for the control of hemorrhage (PATCH) using pelvic binders. Pierrie SN, Seymour RB, Wally MK, et al. Amer J Emerg Med 2021;42:43–48.

While pelvic fractures make up a small percentage of skeletal injuries, they are associated with significant mortality and morbidity, particularly from associated hemorrhage. Early stabilization of the pelvis may have a positive effect on outcomes in patients with these injuries. The authors of this study sought to determine whether pelvic binders could safely be applied to patients in the field to help mitigate these situations prior to formal diagnosis.

This was a prospective randomized trial conducted in a large multi-country area surrounding a level one trauma center. Training materials for prehospital personnel were developed for identifying the potential for pelvic injury, the proper application of pelvic binders, and the details of the study.  The material was presented during regularly schedules training sessions. The purpose of the study was to: 1) determine the feasibility of prehospital application of pelvic binders, and 2) pilot the feasibility of a randomized study evaluating the use of the pelvic binder in a prehospital setting.

Randomization was accomplished through the use of opaque boxes containing either a pelvic binder or weight equivalent sham (not a pelvic binder). The crews were blinded to the content of their assigned box which was randomly assigned to each ambulance. They would not know whether they were using the binder or the current standard of care (stabilization without a binder) until they opened the box. Un-used boxes were returned at the end of each shift and re-randomized.

Over the two year period, 644 patients were screened for entry with 78 patients meeting all inclusion criteria, of which 25 were enrolled in the study. The remaining 53 patients were “missed” by prehospital providers and were not randomized. Twenty-five more patients did not meet all inclusion requirements but were enrolled for a total of 50 patients. Of the total enrolled, 43 consented to participate in the study. Twenty of the 43 patients were treated with binders and the remaining 23 were randomized to the control group. Only 9 of the patients had pelvic ring injuries: two in the pelvic binder group and 7 in the non-binder group. None of these patients had fractures associated with high hemorrhage risk that might have benefited from use of the pelvic binder. Five of these patients were discharged directly from the ED with equal representation from binder and non-binder groups. Nearly half of the non-binder group was admitted to the ICU compared to 5 from the binder group with slightly higher but nonsignificant injury severity score. Two of the binder group patients and 3 of the non-binder group patients required angioembolization to treat bleeding associated with the pelvic fracture(s). No adverse effects from a binder were identified in any patient. Proper binder placement over the femoral trochanters was found in 80% of the patients. The remaining 20% were noted to have been placed too high over of the iliac wings of the pelvis.

The authors concluded that training of personnel to correctly use the devices on the right patients was successfully piloted and that a randomized study of pelvic binder use could be conducted in the prehospital setting.

This study is limited by the fact that the number of patients with this injury is small. There was no information provided about the so-called “missed” patients that were not entered into the study and whether or not they actually had pelvis injuries that were not identified by the treating paramedics. This study did not demonstrate the impact of prehospital pelvic binder use on mortality and morbidity given the extremely small sample size. Showing benefit (or harm) from the prehospital use of a pelvic binder will requires a much larger patient population.

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