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Refusal Heuristics

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Chemical Casualties: Incapacitating Agents

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Ryan Mynatt, PharmD on Virology

Don't you wish someone explained what viral load, viral shedding, and all those other words we use loosely when talking about COVID-19? Well.... our guest on this podcast did, and we think you'll really enjoy getting back to the basics, and then some.

Dr. Ryan Mynatt is a practicing PharmD specializing in infectious disease, and like most academics who know anything about anything, he's responses were a little guarded - which is most appropriate right now.

You can view any of his many publications here.

Oh, he's also on Twitter.

Let us know what you think of the podcast...

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COVID-19 Update: Avoiding the Aerosols

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COVID-19 - EMS Considerations

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C2B Podcast 24 - Needle Thoracostomy

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C2B Podcast 23 - Hyperkalemia

Hyperkalemia Intro

1. Potassium is primarily an intracellular ion responsible for maintenance of the resting membrane potential for normal cell conduction.
2. Serum measured potassium is typically between 3.5 and 5.0 mEq/L.
3. Serum K greater than 5.0 mEq/L is generally considered the threshold for hyperkalemia.
4. Potassium is mostly excreted via the kidneys, and the "classic" hyperkalemia patient is one who has missed several dialysis appointments complaining of paralysis or diffuse weakness.

Causes of HyperK

1. Most commonly, renal failure. 
2. Transcelluar shift 
   1. DKA
   2. Acidosis 
   3. Other acid-base disturbances
3. Medications 
   1. RAAS or ACE inhibitors

Effects of HyperK 

1. Most drastically affect cardiac myocytes 
   1. Conduction between myocytes is depressed, leading to slower conduction and widened QRS complexes, however, the rate of repolarization is increased. 
      1. Leads to ominous “sine wave” pattern on ECG. 
   2. Arrythmogenic 
   3. May produce classic tall, “peaked” T waves on ECG.
2. Stepwise ECG changes in hyperkalemia:
   1. 5.5-6.5 mEq/L - Peaked T Waves
   2. 6.5-7.5 mEq/L - P waves amplitude becomes smaller and PR intervals prolong
   3. 7.5-8.0 mEq/L - QRS becomes wide
3. ECGs are not always sensitive for hyperkalemia. Patients may have a critical K with no changes on the ECG. 
4. Skeletal muscle tissue is also sensitive to hyperkalemia, and patients may present with weakness or paralysis as a result. 
5. Nondescript symptoms such as muscle cramps, diarrhea, vomiting, nausea, and focal paralysis may also be present - but are also not reliable findings. 

Management 

1. Prioritized by a strategy of:
   1. Stabilization of cardiac cell membranes 
   2. Shifting potassium back into the cells 
   3. Eliminating potassium
2. Calcium (Chloride or gluconate) administered to stabilize cell membranes 
   1. Stabilizing effect is transient and relatively short lived 
   2. Calcium Chloride contains roughly 3 times the amount of elemental calcium as compared to Ca gluconate, but is associated with severe complications if extravasation occurs. 
   3. Effects (narrowing of QRS complex, return of more hemodynamic stability) occurs within minutes 
   4. Calcium Chloride - generally, 1 gram is administered over 3 minutes.
   5. Calcium Gluconate - 1 gram over 2-3 minutes 
   6. Repeat either q5min
3. Albuterol / Beta 2 agonists
   1. These act on beta 2 receptors to assist in moving potassium back into the intracellular space 
   2. Albuterol - 10-20mg (inhalation), with most effect noted in 30 minutes 
4. IV Insulin 
   1. Drives K back into the cells (shift)
   2. Generally administered with dextrose unless the patient’s BGL is below 250mg/dL
   3. 10 units IVP followed by 25G dextrose
   4. Incidence of hypoglycemia is high, and this therapy should be administered cautiously
5. Dialysis 
6. Treating reversible cause
   1. d/c RASS or ACE inhibiting medicaitions 
   2. Volume administration

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Diabetic Ketoacidosis

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Rethinking Transcutaneous Pacing

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Are we Placing mCPR Devices too Early?

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An Assault on Preventable Trauma Deaths With Andrew Fisher

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Wailing for Risk Reduction

Wantabe et al. (2018) "Is Use of Warning Lights and Sirens Associated With Increased Risk of Ambulance Crashes?" was the first to definitively link L&S use with ambulance crashes.

Response Crash Rate:

4.6 / 100,000 without L&S

5.4 / 100,000 with L/S

Transport Crash Rate:

7 / 100,000 without L&S

17.1 / 100,000 with L&S

The authors theorize a driving reason behind their observations as such: “During response two providers are in the front and share the cognitive load required to operate an ambulance”.

NHTSA - Proposed L&S Response Benchmark:

• Reduce L/S use to less than 50% during response.
• Less than 5% during transport.

Common arguments for the use of L/S:

• Saves time
• Time is brain/muscle
• Public expectation
  
  

History

The general attitude may stem from the genesis of EMS, where First Aid attendants were not trusted to discern if a patient was stable or not. Ergo, the strategy of the time was to rapidly transport all patients with the underlying presumption that all patients “would” deteriorate unless proven otherwise AFTER arrival at a hospital.

With current advances in prehospital care, the vast majority of injury/illnesses can be effectively managed during the out-of-hospital phase of patient care.

Increased vehicle safety should be championed along with the need to decrease the use of L&S.

• Lime Green colors decreases rate of overall crashes
• Lime Green: 28.2 crashes per 1 million miles travelled
• Red/White: 62.1 crashes per 1 million miles travelled

The average rate of car crashers per 1 million miles is 2.6 / 1 million miles of travel. (Solomon, 1995)

Does it save lives?

(Anderson, 2014)
Study in Denmark looked for morbidity by studying 94,488 patients transported without L&S and found only 152 patients (0.16%) that died the same day as their ambulance transport. A panel of prehospital anesthesiologists reviewed the patient care reports and found 13 (0.02%) with potentially preventable deaths. If every one of these deaths could have been prevented with L&S transport, the “number needed to treat” would have been 5000 extra L&S transports. (Anderson 2014)

(Kupas 1994)
Protocol is used to identify patients that may benefit by the time saved with L&S transport. When using this protocol on 1625 patients, only 130 (8%) were transported using L&S. A review of the 92% of cases where L&S was not used, the receiving physicians did not identify any cases of possible morbidity due to a slower transport.

(Merlin 2012)
Merlin developed an even simpler medical protocol for L&S transport, which reduced L&S transport in this urban New Jersey community from 49.6% to 29.0% for patients transported by ALS providers.

(Marques-Batista 2010)
112 patients transported with L&S found that only five of those patients received a time-critical intervention upon arrival to the emergency department, and none of these procedures was done within the 2.62 minutes saved by L&S transport

(Newgard 2010)
The Resuscitation Outcomes Consortium studied the outcomes for injured patients treated by 146 EMS agencies, transporting to 51 Level I and II trauma centers, in ten North American communities. This large study found no association between survival and EMS time intervals – including response time and transport time.

Does it save time?

L&S use generally only shortens response and transport time intervals by 1.7-3.6 minutes, and transport time only by 0.7-3,8 minutes.
Greenville, NC; Saved average of 43.5 seconds

Fatalities:

9.6 fatalities per 100,000 people per capita related to transportation.
Rear Occupants are 2.7 times more likely to die in a crash (Kahn, 2001)

• Exceeds rate for LEOs and FFs
• Rear occupants 2.7 times more likely to be killed in ambulance crash

But our Fracile Response Time needs to be 8 minutes!

• Stems from 1979 study in Seattle of cardiac arrests
• What matters more is when the first arriving aid is present.
• Now we have widespread T-CPR, rapid dispatch, bystander CPR, and LEO responses w/ AEDs.

EMSA Response Time Standards:

• Priority one calls - 10.59
• Priority two calls - 24.59
• Respond to only 33% of calls w/ L/S
• Have NOT observed any changes in cardiac arrest survival rates.

Time Critical Conditions:

• Rendering a coronary intervention sooner by 10 minutes would decrease death by only 0.4%
  • Rather, work on earlier notification, reduced scene times, and in-hospital workflow.
• Best chance of survival from OOHCA is to obtain ROSC on scene.

Public Perception:

Anecdotally, it is possible some patients hesitate to call EMS for medical emergencies, because they are uncomfortable with L&S responses and increased attention. See the ubiquitous "caller requests no lights or sirens" dispatch.

A 1988 phone survey of the public in Connecticut cited sirens and noise (67/604 respondents) as the primary reason for being uncomfortable in calling EMS during an emergency, and this response was followed by “getting lots of attention” (49/604 respondents). (Smackery 1988) Critz reported that the families of terminally ill patients who died at home sometimes felt anger with EMS, and L&S response was listed as one of the reasons for this.


One-third of drivers responding to a survey in the United Kingdom reported feeling stress when navigating away from approaching emergency vehicles with L&S, and the authors believed that drivers found the interactions with emergency vehicles inconvenient and potentially dangerous. (Saunders 2003)

Legal:

Wolfberg 1996 found that ambulance crashes are the most common cause of insurance claims greater than 10,000 dollars in EMS agencies

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