UMEM Educational Pearls - EMS

Pulseless electrical activity (PEA) is the initial rhythm in up to 25% of out of hospital cardiac arrests.  

This paper is a systemic review and analysis examining if the rate or width of the initial PEA qrs complex was associated with survival.  The qrs complex was either wide (>= 120 ms) or narrow (<120ms) and a frequency of fast (>= 60/s) or slow (<60/s).  7 studies including 9727 patients were included.  Analysis showed:

- mortality was higher in the wide qrs group compared to narrow

- mortality was higher in the slow PEA rate compared to fast

- neurological outcome was better in patients with a fast PEA rate compared to slow.

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A few states have pediatric out of hospital termination of resuscitation protocols.  This study used CARES data to create a termination protocol that was not only linked to ROSC, but also to neurological outcomes.  This study only included medical arrests.
 

21240 children were included in the study where 2326 patients survived to hospital discharge.  A total of 1894 survived with a favorable neurological outcome.  The criteria developed for pediatric TOR in this study had a specificity of 99.1% and a PPV of 99.8% for patient death.  Another set of criteria had a 99.7% specificity and PPV of 99.9% for predicting death or survival with poor neurological outcome.

TOR criteria of death consisted of:

1. unwitnessed arrest

2. asystole

3. arrest not due to drowning or electrocution

4. no sustained ROSC

TOR criteria of death or survival with poor neurological outcome:

1. unwitnessed arrest

2. asystole

3. arrest not due to drowning or electrocution

4. no sustained ROSC

5. no bystander CPR

Bottom line: Pediatric termination of resuscitation in the out of hospital setting can be appropriate under the right set of conditions.

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Previous studies have suggested that a single dose of epinephrine in out of hospital cardiac arrests compared to multiple dose protocols result in a similar survival to hospital discharge rate.  This study aimed to see if single dose epinephrine compared to multiple doses improved survival in the subset of patients that were 1) in a shockable rhythm or 2) received bystander CPR.

This study looked at patients from 5 EMS systems in North Carolina before and after a protocol change from multiple dose epinephrine to single dose epinephrine in cardiac arrest.  1690 patients were included, 19.2% with a shockable rhythm and 38.9% who received bystander CPR.

The study found:

- Survival to hospital discharge was higher in the single dose epinephrine group who received bystander CPR

- Survival rates were similar in the single and multiple dose epinephrine groups for patients who were initially in shockable rhythms, in asystole/PEA and who did NOT receive bystander CPR.

Bottom Line: More studies are needed to support prehospital protocol changes.

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Previous studies have shown that an on scene time of 10-35 minutes was associated with improved survival in pediatric out of hospital cardiac arrests compared to an on scene time of > 35 minutes.  There was no significant difference in overall survival between < 10 minutes and 10-35 minutes of on scene time.

This study involved a total of 2854 pediatric cardiac arrests in the US and Canada.  The patients who had a cardiac arrest during transport were compared to patients who received on scene CPR by equal minutes.

Among patients < 1 year, intra-arrest transport was associated with lower survival to hospital discharge compared to those that were resuscitated on scene.  There was no association for patients > 1 year.

Bottom line: This study supports resuscitating in place for pediatric cardiac arrests, especially in patients < 1year.

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This was a review of the cardiac arrest registry of Norway between 2016-2021.  The incidence of pediatric out of hospital cardiac arrests was 4.6 per 100,000 child years and significantly higher in children < 1 year (20.9 per 100,000 child years).  There was an overall 18% one year survival rate in the 308 patients included.  

Leading causes of arrests were choking, respiratory disease, drowning and SIDS, making up 67% of cases.

73% of the arrests were initially asystolic and 14% were PEA on EMS arrival.  The presence of shockable rhythms increased with age and VT/VF were the initial rhythm in up to 15% of the 13-17 year age group.  

88% of patients received bystander CPR ( with 68% receiving both chest compressions and ventilations).  A minority of these patients were in a shockable rhythm, but 7 total patients were in refractory VF.  Mechanical CPR devices were used in 35 patients aged 11-17.  ECMO was started in 19 cases.

Bottom line: The rate of bystander CPR in this study was very high and other jurisdictions can attempt to learn from the system in place in Norway to increase their local prehospital interventions.

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Question

EMS may call the hospital to obtain online medical direction when a patient does not wish to come to the hospital.  One difficult task faced by the physician at the hospital is determining the decision making capacity of the patient.  There is currently no nationally recognized standard protocol for physicians providing EMS oversight in this situation.  

The four components involved in the determination of capacity are: understanding, appreciation, reasoning and expression of choice.  This study used a modified Delphi approach with 19 physician experts to develop standardized steps to guide best practices for physicians who are called in real time about a patient refusing EMS transport.  Consensus was defined as 80% agreement.  

The example worksheet with the compilation of recommendations is attached.

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Attachments

• Refusal checklist table-670fb6a9192a8.docx (105 Kb)

Background:
Despite a lack of reliable evidence, sodium bicarbonate (SB) still appears in various protocols as a potential therapy for patients in cardiac arrest. Local EMS protocols also endorse the use of (SB) in specific scenarios such as: tricyclic overdose and hyperkalemia. EMS systems struggle to articulate best practices with respect to indications for SB administration. 

Patients/methods:
Study authors conducted a scoping review of existing literature. The review included in hospital and out of hospital patients with cardiac arrest. Despite multiple studies looking at this question, a total of 12 were included in the final analysis. Criteria for inclusion were as follows: RCT or observational studies looking at patients aged 18 or older who experienced a cardiac arrest. Important outcome metrics incorporated: neurological recovery and survival to discharge. 

Results:
The retrospective review failed to demonstrate a reliable association between survival and administration of sodium bicarbonate. Despite significant limitations (different study populations, retrospective designs), there remains insufficient evidence to consider routine administration of bicarb in the setting of cardiac arrest. 

Bottom line:
Empiric administration of SB is not linked to a reliable benefit. SB may be considered for specific indications (tricyclic overdose, hyperkalemia) but is unlikely to improve outcomes such as neurologic recovery or hospital discharge. EMS systems should avoid recommending routine SB administration for patients with out of hospital cardiac arrest.

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This study looks at the efficacy of ketamine vs. midazolam for the prehospital sedation of acutely agitated patients, examining the need for repeat sedation (by EMS or in the ED), adverse events and length of stay.

A greater number of patients required repeat sedation within 90 minutes with initial ketamine dosing compared to midazolam. There was no difference in patients receiving repeat sedation within 20 minutes between the two groups.

There were no significant differences in time to repeat sedation, total sedation doses (by EMS or in the ED), use of bag valve mask ventilation or intubation, use of physical restraints, admission location/level of care, or length of stay in the Emergency Department (ED), hospital, or Intensive Care Unit.

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BACKGROUND:
Cardiac arrest is time sensitive disease. Despite significant advances in resuscitation technology such as eCPR and mechanical compression devices, early basic life support interventions (specifically bystander CPR) are strongly associated with survival. EMS systems must advocate for early initiation of bystander CPR. Dispatch Assisted CPR (DA-CPR) is one of several strategies designed to improve outcomes and encourage early compressions. To optimize survival, EMS systems should achieve a comprehensive understanding about barriers to succesful initiation of DA-CPR. 

METHODS AND OUTCOMES:
49,165 patients with out of hospital cardiac arrest were eligible for inclusion the study, and over 36,000 underwent successful DA-CPR. The study's primary outcome was good neurological recovery at hospital discharge. Secondary outcomes included: prehospital return of spontaneous circulation (ROSC)and survival to hospital discharge. The authors defined successful DA-CPR when bystanders initiated compressions and continued resuscitation until the arrival of EMS. 

RESULTS:
Quite a few results were consistent with prior studies. Unsuccessful DA-CPR was associated with: 

• Advanced patient age (>65 yo) 
• Arrest location in private or non metropolitan place
• Lack of recognition of cardiac arrest 
• Lack of bystander education on cardiopulmonary resuscitation

Successful DA-CPR was more likely associated with the presence of family members at the scene and improved neurological recovery. Witnessed arrests were also more likely to receive successful DA-CPR. Not surpringly, patients in the successful DA-CPR group also exhibited improved survival to discharge and prehospital ROSC. 

BOTTOM LINE:
Though the study is retrospective and involves a host of confounding variables, EMS systems continue to identify modifiable factors linked to the delivery of DA-CPR. Improved community CPR education and dispatcher training may contribute to higher DA-CPR rates. 

BALTIMORE, MD,  SPECIFIC PEARL:
Baltimore metropolitan jurisdictions are collaborating with the CPR LifeLinks program to address DA-CPR. The CPR LifeLinks program a national initiative “to help communities save more lives through implementation of telecommunicator and high performance CPR programs."  https://www.911.gov/projects/cpr-lifelinks/

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Several studies have shown that patients who require a resuscitative thoracotomy (RT)  have a higher odds of survival if they are transported by police or in private vehicles.  This study examined 195 patients who required RT to see if prehospital intubation and out of hospital time (OOHT) affected ROSC rates.

There was no association between OOHT and ROSC and no association of OOHT and survival.  The mean OOHT for this study was only 25 minutes which is faster than other studies.  

The odds of ROSC were lower in patients who had ANY intubation attempts prior to arrival.

Bottom line: BLS airway management (or supraglottic placement) may be more beneficial for the trauma arrest patient in the prehospital setting.

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Maternal morbidity continues to increase in the US with a mortality rate in 2021 of 39.2 deaths/100,000 live births.  There has been an intense focus on training and quality improvement within hospitals, but not much has changed in the prehospital education arena.  This study aimed to quantify the complications encountered by EMS clinicians.  

In the 2018-2019 EMS dataset used, there were a total of 56,735,977 EMS activations which included 8641 out of hospital deliveries, 1712 documented delivery complications and 5749 records of newborns.

1% of the out of hospital deliveries had a documented complication for the mother.  Of these complications, 94% were for hemorrhage, 6% for abnormal presentation, 0.2% for shoulder dystocia, and 0.4% for nuchal cord.  

Few patients had medications given, including 0.4% receiving oxytocin.  no patients received prehospital blood transfusion or TXA.  Of note, in the years since this data was obtained, TXA and whole blood have started to appear on more medic units, but it is still not necessarily commonplace.

Bottom line: While still rare, prehospital delivery does occur and EMS should be prepared for any possible complications.  Medical directors should look at their jurisdictional/state protocols to see if oxytocin/TXA or whole blood should be included (if not already available).  EMS clinicians should be educated on up to date management of OB emergencies.

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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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Attachments

• 1402JEMSbc-p07 BCHEMS-659aec1e4a6bf.jpeg (186 Kb)

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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