UMEM Educational Pearls - EMS

The short answer is yes, pediatric trauma patients without blood pressures recorded from EMS had a higher mortality (4.3%) compared to pediatric patients that did have a recorded blood pressure (1.1%). This is based off of a prehospital study conducted in Japan.

Prehospital vital signs are left out more often in pediatric patients compared to adults. Of those vital signs that are recorded, blood pressure is the most common one left off.

There can be several barriers to obtaining a blood pressure on the pediatric patient in the prehospital setting: lack of properly sized equipment, an uncooperative child, and lack of education. However, the inability to obtain a blood pressure can also be due to the patient being more severely injured and having other skills performed or was unable to be obtained due to poor perfusion. In this study, those who did not have a recorded blood pressure also had a lower GCS score and a higher injury severity score.

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BACKGROUND:
The ideal strategy for out of hospital ventilation is a matter of long standing debate and clinical controversy. To date, improved out of hospital outcomes have been associated with non invasive (BVM) and supraglottic airway (SGA) management strategies. A recent, prospective trial featured in Resuscitation offers a slightly different perspective. The trial enrolled 420 adult patients with refractory out of hospital cardiac arrest due to a shockable rhythm. The study looked at outcomes for patients who received endotracheal intubation (ETI)  or supraglottic airway placement. Importantly, the study involved a high volume cannulation center and  codified screening criteria for eCPR including:  a) ongoing arrest despite 3 shocks, b) treatment with amiodarone, c) mechanical CPR and d) anticipated time to arrival at ECMO cannulation center of <30 minutes. 

OUTCOMES:
Compared to patients in the SGA group, patients receiving ETI demonstrated: 

• Significantly higher Pa02
• Significantly lower PaC02
• Significantly higher pH 
• No significant differences in lactic acid level 
• Improved neurological outcomes (CPC score)

In accordance with the study institution's cannulation criteria, more patients in the SGA group were deemed ineligible for ECMO. 

BOTTOM LINE:
In this single center study, patients who received ETI as a primary strategy for out of hospital airway management were more likely to meet ECMO eligibility critera and exhibit improved oxygenation and ventilation.

While this is not necessarily a practice changing article, it illustrates the complexities inherent in out of hospital cardiac arrest management. EMS has largely transitioned from a “scoop and run” cardiac arrest strategy to a plan that emphasizes treat in place. For patients who may benefit from E-CPR, additional research is indicated to shed light on best out of hospital resuscitation (and airway management)  practices.

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7,365 suicide related cardiac arrests were included in this study that included a several year study period in Queensland Australia.  Cardiac arrests where resuscitation was attempted by EMS and where circumstances were concerning for suicide were included.  ROSC rates were 28.6% with survival at 30 days being only 8%.  30-day survival for medical cardiac arrests in this jurisdiction was 16.4%.  Overdose and poisoning had the best survival rate (19.9%), while hanging and chemical asphyxia were the worst (7.3 and 1.1% respectively).

Bottom line: Survival rates for suicide related out of hospital cardiac arrest were worse compared to other causes of medical arrest.  Suicide prevention should become a focus with emphasis on early identification and treatment of people at high risk of suicide.  While EMS is well trained on the management of cardiac arrest, training should also emphasize suicide risk assessment and identification.

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Vital signs in children can be difficult to remember since they vary with age.  Using a standardized card or app (such as PALS) can help EMS clinicians remember the values.  Most pediatric vital sign reference ranges were derived from samples of healthy children in the outpatient setting (ie PALS).  This study attempted to validate a range of pediatric vital signs that were more accurate in predicting the need for prehospital interventions compared to the standard PALS vital sign ranges. The thought was that by using EMS data, these vital sign ranges could better alert EMS to patients in need of acute intervention.

The authors used a large EMS database to determine the vital signs for the patients age and correlated that to prehospital interventions (including IV, medication, EKG, advanced airway management, ect).  They used the <10% and >90% for the age values (termed "extreme" vitals signs) as a cut off to be considered abnormal.  Using the EMS derived values, 17.8% of the encounters with an extreme vital sign received medication.  If the PALS abnormal vital sign range was used, only 15.2% of those patients were given medications.  Overall, encounters with an extreme vital sign had a higher proportion of any intervention being performed compared to other vital sign criteria (i.e. only 33.7% with PALS).

These extreme vital signs also had a greater accuracy in predicting mortality.

Bottom line: While vital signs are based on physiology that does not change based on location, using a seperate criteria for the EMS population, can improve discrimination between sick and sicker patients and hopefully allow EMS to recognize and intervene on sicker patients sooner.

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The 2nd most common reason for EMS activation is chest pain.  In this study, paramedics were asked to complete the HEAR (history, EKG, age, risk factor) score, EDACS (ED Assessment of chest pain score), the Revised Geneva Score and the PERC (Pulmonary embolism rule-out criteria) for all patients older than 21 who presented with chest pain.  The positive and negative likelihood ratios (LR) of the risk scores in relation to 30 day MACE and PE risk were calculated.

837 patients were included in this study with 687 patients having all 4 scores completed.   The combination of HEAR/PERC had the best negative LR (0.25) for ruling our MACE and PE at 30 days.   However, these scores, alone or in combination, were not sufficient to exclusively guide treatment or destination decisions.  Adding biomarkers (ie troponin or Ddimer to the prehospital setting) could improve the usefulness of these scores.

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BACKGROUND:
Critical care transport teams are tasked with extending specialized care to the bedside. Given the uptick in COVID and ARDS cases, there are increasing demands for the transport of patients proned for respiratory compromise. An air medical service in British Columbia (BC) published their experience with transporting intubated patients in the proned position. The BC service utilizes 2 trained flight paramedics and conducts transports via pressurized fixed wing and non pressurized rotor wing aircraft.  The small, retrospective study of 10 patients demonstrated feasibility of this practice. No extubations were recorded in the study population. 6/10 patients experienced >6% increase in oxygen saturation and no medical lines were disconnected during transport.  

BOTTOM LINE:

• Proning patients for air medical transport is possible but incorporates significant logistical and educational challenges 
• Evidence base for proning in air medical transport is insufficient to inform comprehensive conclusions about risks and benefits

BALTIMORE, MD SPECIFIC PEARL:

• Currently, one local helicopter service  will accomplish missions involving proned patients. Therefore, attention to optimizing vent settings prior to transport is imperative

BONUS AVIATION ENTHUSIASTC SPECIFIC PEARL: 

• BC air medical services is the largest integrated provider of helicopter EMS in Canada. They operate four Sikorsky S-76 aircraft. The S-76 platform is a large twin engine helicopter capable of transporting 2 patients at a time. 
  http://www.bcehs.ca/our-services/programs-services/critical-care-program

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US hospitals have traditionally been concerned that without an ambulance diversion protocol that they would be overrun with EMS arrivals.  EMS had been concerned that without diversion there would be extended wait times at the hospital.  This study looked at EMS arrivals one year (2021) before the elimination of diversion and compared the number to one year after diversion elimination (2022).  

This study of a single level 1 trauma center showed that there was NO difference between the number of EMS arrivals per day (84 vs 83, p = 0.08), time to room for ESI 2 patients, time to head CT in acute stroke patients OR ambulance turn around time (16 min vs 17 min, p = 0.15).

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BACKGROUND
 
EMS systems differ in staffing and composition. The Japanese model utilizes “doctor cars” which bring a physician and nurse to the scene of a critical patient encounter. Personnel on the “doctor cars” are able to perform advanced therapies such as REBOA, finger thoracostomy, and chest tube thoracostomy. As physician EMS fellowships continue to expand in the United States, it is helpful to examine the utility of physician response incorporated into prehospital emergency care. 

 
THE STUDY

A nationwide retrospective cohort study including over 370,000 patients examined the impact of Japan “doctor cars” upon in hospital survival. Doctor cars responded to 2361 trauma patients, and traditional Ground Emergency Medical Services (GEMS) units cared for 46,783 trauma patients.  The study’s primary outcome was survival to discharge.  

The adjusted odds ratio for survival was significantly higher in the exposure group served by the doctor cars. The study suggests that there may be a role for augmenting ground EMS personnel in the response to critical injuries. Via logistic regression, the study controlled for multiple other variables such as age, sex, prehospital vital signs, out of hospital time, and injury severity score (ISS).  

• At hospitals caring for >50 trauma patients per year, the impact of doctor cars upon in hospital survival was not statistically significant 
• Not surprisingly, patients cared for by the doctor car team had a longer time to hospital arrival 
• Adult patients with higher ISS scores had a significant improvement in survival  

BOTTOM LINE
 
This study is far from definitive but contributes to a growing body of literature addressing how EMS physicians integrate into prehospital systems.

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BACKGROUND: Prehospital (EMS) clinicians are positioned on the front lines of health care. With respect to stroke identification and treatment, early recognition is essential to positive outcomes. Considerable variability exists within EMS documentation. Despite considerable variability in documentation, the establishment and tracking of core stroke metrics serves as a benchmark to gauge performance and outline strategies for improvement. 

METHODS: Authors conducted a retrospective, observational analysis of EMS encounters (2018-2019) which ultimately received a diagnosis of an "acute cerebrovascular event." Hospital based diagnoses included: hemorrhagic stroke, ischemic stroke, or transient ischemic attack. The data set was comprised of a statewide EMS documentation and a state wide acute stroke registry. Authors examined compliance with six core performance metrics which included measurement of blood glucose, documentation of last known well time, and on-scene time < 15 mins for patients with suspected stroke. During the 18 month study, almost 6000 encounters met criteria for inclusion. 

RESULTS: EMS documentation remains a significant source of variability. EMS crews were largely compliant with blood glucose measurement. However, last known well time had the lowest (24%) documentation rate. Patients diagnosed with subarachnoid hemorrhage had the lowest rate of compliance with metrics. 

BOTTOM LINE: Accurate prehospital stroke diagnosis remains a challenge. Consistent data collection and benchmarking remains an important first step in the evaluation of performance. Higher NIHSS scores and ischemic strokes are linked to higher rates of metric compliance. 

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The typical bag valve mask ventilator (BVM) for adults has a reservoir volume between 1500-2000 mL depending on the manufacturer while the volume is between 500-1000 mL for a pediatric BVM.  When trying to obtain the recommended tidal volume of 6-8 mL/kg (500-600 mL for the typical adult), one thought was that a pediatric BVM could be used with adult patients so as to avoid iatrogenic barotrauma.  This has been studied on manakins using an oral pharyngeal airway, supraglottic airway and endotracheal tubes (ETT) and has been successful.  This study attempted to obtain the same results in the back of a moving ambulance.  Paramedics and EMTs, squeezing pediatric and adult BVMs with one hand, bagged adult manakins in the back of a moving ambulance (without lights and sirens).  The average tidal volume was recorded using various types of airways (i-gel, King airway and ETT).

Volumes delivered with the pediatric BVM were significantly lower than the tidal volumes with adult BVMs across all airway types suggesting that in the moving ambulance, using pediatric BVMs on an adult patient would not be appropriate.

The I-Gel and King airway provided similar tidal volumes which were not statistically different than volume delivered through the ETT.

EMTs consistently delivered 50% less tidal volumes compared to paramedics. The authors suggested that perhaps the additional training and pathophysiology knowledge that paramedics have could also be important with a skill that is considered basic. 

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BACKGROUND:
Emergency Medical Services (EMS) systems, especially those within urban jurisdictions, struggle to effectively meet the needs of patients experiencing complications of substance use. The exceedingly high burden of disease, coupled with potentially life-threatening sequelae of substance use stresses EMS systems beyond capacity. The current paradigm of naloxone administration and subsequent refusal of care places patients at an increased risk of death and other complications such as aspiration. EMS agencies, in collaboration with area hospitals, public health experts, and addiction medicine specialists are devising novel mitigation strategies to reduce morbidity and mortality. “Leave behind” naloxone, peer outreach, and 911 diversion programs are part of a more over-arching strategy that links patients to longer term, definitive health care resources within the community. EMS-administered buprenorphine has emerged as a novel treatment modality for prehospital patients. This study examined outcomes of patients who were a) experiencing symptoms of opiate withdrawal and b) given buprenorphine by a credentialed EMS paramedic. Patients included in the buprenorphine cohort scored >5 on the clinical opiate withdrawal scale (COWS), regained “full decisional capacity” after being resuscitated from an overdose, and were > 18 years of age. The study excluded pregnant patients and those who took methadone within 48 hours prior to an EMS encounter. After consultation with an EMS physician, patients received 16 mg of sublingual buprenorphine. Paramedics could administer ondansetron and an additional 8 mg of buprenorphine for continued symptoms. Finally, the study cohort was matched to a similar group of patients who were treated by “non buprenorphine equipped” ambulance. Outcomes of interest included: rates of repeat overdose, likelihood of transport, and follow up with addiction medicine/substance use resources. The study was conducted in an urban EMS system with robust EMS physician oversight and advanced life support transport units.

RESULTS:
Patients receiving buprenorphine did not experience a reduction in repeat overdose. However, they were less likely to be transported. The buprenorphine cohort, predictably, was much more likely to be enrolled in a substance use treatment program within 30 days of the initial encounter. Paramedics spent more time on scene with the buprenorphine cohort.  Though far from a conclusive study, the manuscript adds to a growing body of literature that attests to the feasibility of paramedic administered buprenorphine.

BOTTOM LINE:
Though far from a conclusive study, buprenorphine administration by EMS paramedics is feasible. The increased linkage to care and decreased rates of transport will hopefully motivate EMS systems to consider novel strategies for harm reduction. The study authors opine that buprenorphine may “be a promising…link to long term recovery.”

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Patient restraint is a high risk, high liability encounter for all levels of emergency medical practitioners. Often, acutely agitated patients benefit from de-escalation. This can be difficult to achieve in a resource limited setting. McDowell et al (2023) performed a comprehensive review of patient restraint encounters. Their work describes risk factors linked to adverse outcomes. Specifically, highly agitated patients who are physically and chemically restrained can experience clinical deterioration. The review also highlighted risks to EMS clinicians as well such as: needle stick, physical inury, and downstream litigation. 

Bottom line: 

Patient restraint represents a high risk encounter. 

• De-escalation is preferred vs. physical restraint 
• Chemical restraint likely preferred vs. physicial restraint 
• Restraint can worsen agitation and contribute to acidosis, positional asphyxia, cardiac arrest, and other untoward outcomes
• DO NOT place restrained patients in the prone position 
• Policies for restraint should be vetted, socialized, and regularly reviewed with all stakeholders 

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Bystander CPR increases out-of-hospital CPR survival and direction by 911 telecommunicators increases the frequency of bystander CPR.  The majority of 911 centers use Medical Priority Dispatch System which walks 911 telecommunicators through a series of questions that give different instructions based on the caller's answers.  Studies have shown out-of-hospital cardiac arrests are only recognized between 79-92% of the time and telecommunicator instructions for CPR can take between 176-285 seconds.

This study reviewed recorded 911 calls of patients who were found to be in cardiac arrest. Calls where the caller was not with the patient and confirmed overdoses were some of the call types that were excluded.

Out of 65 reviewed calls, 28% were not recognized during the actual call.  When they were reviewed, 8/18 of the calls were deemed to be recognizable.  Themes that were noted were: incomplete or delayed recognition assessment (ie uncertainty in breathing), communication gaps (callers were confused with instructions or questions), caller emotional distress, delayed repositioning for chest compressions, non essential questions and assessments, and caller refusal/hesitation or inability to act.

Bottom line: In addition to bystander CPR training, education on the process and questions involved in calling 911 could be helpful in an emergency.  

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There is room for improvement with respect to rates of meaningful neurological survival in patients experiencing out of hospital cardiac arrest. Post resuscitation blood pressure goals remain a matter of debate. Though a MAP of >65 mm Hg is often cited as "desirable" in the post cardiac arrest setting, some experts have advocated for a higher MAP goal to increase cerebral perfusion pressure and improve outcomes. 

This study was a retrospective review and meta-analysis that examined post cardiac arrest patients with MAP goals < 70 mm Hg and > 70 mm Hg. Over 1000 patients were included in the final meta-analysis. The primary outcome was pooled mortality. Secondary outcomes included neurologically meaningful survival, dysrhythmia, and acute kidney injury. The study detected no statistically significant difference in survival. Neurological outcomes were also similar between the two groups of resuscitated patients with out of hospital cardiac arrest. However, the study revealed statistically significant decreases in ICU length of stay and mechanical ventilation time. 

As with any retrospective review, there are important limitations to consider. Among them: Few RCTs were included and all of them were conducted in European countries. Generalizability may be limited given the differences in emergency medical services systems and resuscitation protocols. 

Study authors recommend tailoring resuscitation goals to the individual patient since arrest physiology, comorbidities, and other factors influence a patient's post cardiac arrest course. 

Bottom line: 
There is insufficient evidence to recommend arbitrary MAP goals in patients resuscitated from out of hospital cardiac arrest. 

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