UMEM Educational Pearls - By Ben Lawner

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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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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BACKGROUND:
Prehospital administration of whole blood involves some areas of controversy. Though theoretical benefits are clear, concerns about logistics and timing of blood often dominates the discussion. This study was a retrospective analysis of prehospital blood administration within an urban EMS system from 2021-2023. Primary endpoints included: time to administration and in hospital mortality. 

PATIENTS/METHODS:
The study population included patients presenting to the EMS system with signs and symptoms of hemorrhagic shock (SBP<70 or SBP<90 + HR> 100, n=61) and who received at least 1 unit of prehospital blood (PHB).  The EMS system administered blood in conjunction with an advanced resuscitative bundle (calcium, TXA, blood). Isolated head injuries and blunt trauma patients were excluded from the analysis.  The control group (n=82) was comprised of patients in the system's trauma registry presenting to EMS PRIOR to the initiation of whole blood and who exhibited similar clinical crtieria. 

RESULTS:

• PHB patients had significantly higher BP upon arrival to hospital
• Following multivariate regression analysis, each minute delay to blood administration was linked to an independent increase in mortality of 11%
• PHB group demonstrated lower in hospital mortality 
• PHB group linked to longer prehospital time interval (increased scene times) 

BOTTOM LINE:
In this prospective study conducted within an urban EMS system, patients receiving prehospital whole blood demonstrated improved vital signs and reduced mortality when compared to a control group. Slightly extended prehospital time intervals for patients receiving PHB may be offset by the measured benefits of whole blood therapy.

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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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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

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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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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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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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Recent advances in resuscitation science have enabled emergency physicians to identify factors associated with good neurologic and survival outcomes. Cases of persistent ventricular dysrhythmia (VF or VT) present a particular challenge to the critical care provider. The evidence base for interventions in shock refractory ventricular VF mainly consists of case reports and retrospective trials, but such interventions may be worth considering in these difficult resuscitation situations:

1. Double sequential defibrillation
-For shock-refractory VF, 2 sets of pads are placed (anterior/posterior and on the anterior chest wall). Shocks are delivered as "closely as possible."^1,2

2. Sympathetic blockade in prolonged VF arrest
-"Eletrical storm," or incessant v-fib, can complicate some arrests in the setting of VF. An esmolol bolus and infusion may be associated with improved survival.³  Left stellate ganglion blockade has been identified as a potential treatment for medication resistant VF.⁴

3. Don't forget about magnesium! 
-May terminate VF due to a prolonged QT interval 

4. Invasive strategies
-Though resource intensive, there is limited experience with intra-arrest PCI and extracorporeal membrane oxygenation. Preestablished protocols are key to selecting patients who may benefit from intra-arrest PCI and/or ECMO. ⁵

5. Utilization of mechanical CPR devices 
-Though mechanical CPR devices were not officially endorsed by the AHA/ECC 2010 guidelines, there's little question that mechanical compression devices address the complication of provider fatigue during ongoing resuscitation. 

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Hyphema is an urgent ophthalmologic condition. Due to the high risk of rebleeding and increased intra-ocular pressure, strict follow up with an ophthalmologist is warranted. SELECTED low grade hyphemas in reliable patients may be managed on an outpatient basis. Some pointers that may be helpful for the EM inservice exam: 

• Measurement of intra-ocular pressure (IOP)  is crucial to proper treatment and prognosis.
• Many drugs are available to lower IOP, these are generally used in association with opthalmologic consultation
  ->acetazolamide (has potential to "sickle" RBC's)
  ->aminocaproic acid
  ->B blockers
• Hyphema > 5 days are associated with high incidence of synechiae formation
• Avoid NSAIDs/ ASA
• Eye patching,  HOB (head of bed) elevation recommended
• Corneal bloodstaining indicates a poor prognosis
• Incidence of rebleeding estimated at 30-40%
• Graded from 0-IV. Grade IV hyphemas cover the entire anteror chamber; often called, "8 ball" or "blackball" hyphema. Grade 0=only visible on slit lamp.
• Trauma is most common etiology
• Low IOP and trauma? ---> Rule out globe rupture! 

General indications for "very urgent" ophthalmologic consultation:

• Severely impaired visual acuity=greater rebleeding risk
• Patient with known SCD or sickle cell trait
• Visible blood staining of cornea
• High grade, covering > 1/3 of anterior chamber
• Delayed presentation (risk of synechiae / vision loss due to IOP) 

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BACKGROUND: 

For the first time since its publication, the centers for disease control has dedicated an entire issue of their Morbidity and Mortality Weekly Report to an emergency medical services topic. Vol 55 RR-1 reviews the, "Guidelines for Field Triage of Injured Patients." The report represents a consensus opinion of national experts in EMS, EM, and trauma care. It outlines which patients may be best served via transport to a trauma center.

CRITERION LINKED TO SEVERE INJURY  (Consider transport to nearest TRAUMA CENTER) 

• GCS < 14, SBP < 90 mm Hg, RR < 10 or > 29 per minute (or less than 20 for infants) 
• Penetrating wounds to neck, torso, head
• Flail chest, two or more proximal long bone fractures
• Proximal extremity amputation
• Paralysis
• Open or depressed skull fracture
• Older patients on anticoagulation

From the MMWR: "The National Study on the Costs and Outcomes of Trauma identified a 25% reduction in mortality for severely injured patients who received care at a Level I trauma facility." 

EXTRAS: 

The remainder of the report details the triage decision making process, explains trauma center capabilities, and provides an interesting and detailed review of trauma transport criteria. Link to the current issue is attached.

http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5801a1.htm

To echo Dr. Rogers' fantastic airway tips:

When considering an intubation or managing an emergent respiratory concern, keep the "P"s of intubation in mind:

1. P osition:  No intubating on the floor!  Don't get sucked into the patient's oropharynx! Maintain an appropriate distance. Align the airway axes. Sniffing position is utilized for non traumatic adult airways; this involves flexion of the lower c-spine and a bit of extension at the upper cervical levels. Take off cervical collars. Use pillows / blankets to align the external auditory canal (EAC) with the sternal notch to help w/visualization. Cricoid pressure is NOT designed to facilitate passage of the ETT- it MAY help prevent excessive gastric insufflation.

2. P reparation: Two tubes. Two blades. Two intubators. Plan B(ougie) or Plan C(cric). Though your emergency airway plans may differ, think of ALL airways as potentially difficult ones. Respect the epiglottis. 

3. P reoxygenation: 100% via NRBM when possible to ensure oxygenation and nitrogen washout. In patinets with at least some reserve, this will help to avoid pulse ox pitfalls. True RSI does NOT involve positive pressure ventilation.

4. P remedication: Know your sedatives in advance. Etomidate ? Ketamine ? Diprivan ? Whatever your agent of choice, know indications and drug dosages. Emergent RSI is a less than ideal time to access Epocrates.

5. P aralysis:  This is pretty much the point of no return. Administration of paralytics commits you to securing a patient's airway. Both rocuronium and succynylcholine can be dosed at 1 mg/kg IV.

6. P ass the tube: What Dr. Rogers said.

7. P osition confirmation: Direct visualization of the tube through the glottic opening coupled with end tidal Co2 is ideal.

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The Prehospital Acute Neurological Treatment and Optimization of Medical Care in Stroke Study (PHANTOM-S) was a randomized prehospital  clinical trial. On certain days, a dedicated Stroke Emergency Mobile (STEMO) responded to possible ischemic stroke incidents. Outcomes measured included time to thrombolysis and adverse events such as intracerebral hemorrhage. As opposed to usual prehospital care, a STEMO ambulance was equipped with a CT scanner, point of care laboratory, and a neurologist. According to the study, STEMO use resulted in reduced time to treatment (tPA) without adverse events. 

Though this trial did not specifically measure clinical endpoints, it addresses issues central to the delivery of specialized prehospital care:

1) Are there certain conditions which might warrant a tailored, super-specialized EMS response?
2) Are EMS systems capable of delivering definitive care to the patient as opposed to delivering the patient to definitive care? 

Stateside study has already started.  The Houston Fire Department, in partnership with UTHeath, has already loosed a "Mobile Stroke Unit" on the streets. Like the STEMO, the specialized ambulance will be University hospital based, carry a neurologist, and have the capability to administer tPA. 

STEMO pictures courtesy of the "NeuroEMS Blog"
http://www.neuroems.com/2014/05/14/tpa-in-the-truck-results-of-the-phantom-s-trial/

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