C02: Bradycardia Flashcards
What HR is considered bradycardia, per BCEHS CPGs?
less than 50bpm
if your patient is symptomatic at a rate of 50 or more, consider other causes
What are “symptomatic findings” in the context of bradycardia?
- Use CHADS
- Chest pain (ischemic)
- Hypotension
- Acute heart failure (pulmonary edema)
- Decresed LOC
- Shock
What are the two primary goals in the management of symptomatic bradycardia?
- Optimize hemodynamics!
- Identify and treat the underlying cause
remember: resuscitate before you differentiate!
Describe the most appropriate care for a patient with a HR of 42, orthostatic pre-syncope, and mild dyspnea. All other findings are unremarkable
- Supportive care and transport
- The patient does not meet CHADS criteria for requiring pre-hospital management of bradycardia (orthostatic pre-syncope is not DLOC, and mild dyspnea is not the same as acute CHF)
- Investigate for causes of bradycardia and provide ongoing monitoring
Describe the role of atropine in patients with 1st, 2nd, and 3rd degree heart block
- 1st-degree: atropine is the treatment of choice
- 2nd and 3rd degree: atropine is less likely to be successful, but SHOULD still be attempted if appropriate.
You repond to a patient who presents with DLOC, chest pain, and hypotension. Their HR is 34BPM. While performing your physical exam you note a large surgical scar on their chest, and they inform you they had a heart transplant 3 years previous. Which medication is specifically contraindicated in this patient population?
atropine!
Atropine is ineffective and potentially harmful in patients who have had a heart transplant.
You are treating a 120kg patient for symptomatic bradycardia. After adminstering a 0.6mg dose of atropine, you note that their HR is paradoxically slowing and they complain of worsening symptoms. What should you do next?
Administer additional atropine! Paradoxical bradycardia is an adverse effect of atropine when given too slowly or in too low of a dose. You should immediately give more atropine to reverse the effect.
What is the preferred pharmacological therapy for patients with symptomatic bradycardia and marked hemodynamic instability? (i.e. they are peri-arrest)
Epinephrine
* Consider push-dose epinephrine (10mcg IV push) as a bridge to epinephrine infusion (2-10mcg/minute)
Describe the components and pathophysiology of BRASH syndnrome
- Bradycardia
- Renal failure
- AV nodal blockers (CCB or BB)
- Shock/hypotension
- Hyperkalemia
- BRASH syndrome describes a vicious cycle of cascading cardiorenal failure in patients who are taking AV Nodal blockers
- Bradycardia leads to poor renal perfusion, leading to decresed excretion of potassium and worsening bradycardia.
- AV Nodal blockers inhibit normal compensation, and synergize with increased potassium, leading to worsening shock, decreased renal perfusion, and a positive feedback loop culminating in death
Describe common, field-reversible causes of bradycardia
- Remember this or your patients will D.I.E.
- Drugs (CCBs, B-blockers, Digoxin, Amiodarone)
- Ischemia (Especially Inferior or RV infarct)
- Electrolytes (hyperkalemia)
- Also consider hypoxia and increased vagal tone, especially in pediatric patients
Should you correct bradycardia in a patient with signs of myocardial infarction?
- Only if they are significantly hypotensive (i.e. peri-arrest)
- In the setting of myocardial infarction, bradycardia is often compensatory and somewhat beneficial. Be cautious of initiating rate-specific therapies as these may increase myocardial oxygen demand and extend the margins of infarct.
Describe atropine dosing in symptomatic bradycardia
- 0.6mg IV/IO push. Repeat PRN to a maximum dose of 0.04mg/kg (approx. 3mg in most patients)
- Be sure to give as a RAPID push. If paradoxical bradycardia develops, give additional atropine
What three pharmacological interventions are indicated specifcally in the setting of hyperkalemia? Include dosages
- Calcium Chloride: 1g IV push, may repeat at 5 minute intervals
- Sodium Bicarbonate: 1 mEq/kg IV/IO slow push. May repeat 0.5 mEq/kg IV/IO slow push every 10-15 minutes as required
- Salbutamol: 10-20mg via nebulizer or 400mcg via MDI PRN
Describe how epinephrine is given as an infusion for symptomatic bradycardia (i.e. what is the indication, how is it prepared, what equipment is used, what are the drip rates)
- Used in settings of symptomatic bradycardia refractory to atropine or in peri-arrest settings
- 2-10mcg/minute infusion
- add 1mg epinephrine to a 250mL bag with a 60gtts/mL drip set. 1gtt/second = 4mcg/minute (adjust accordingly, so 1gtt/2sec=2mcg/mL, etc.)
Which electrodes must be placed on a patient prior to initiating transcutaneous pacing?
- The limb leads
- Therapy electrodes (the “pads”)
What is appropriate positioning of the therapy electrodes for transcutaneous pacing?
either anterolateral or anterior-posterior is acceptable
What is the preferred agent for sedation when providing transcutaneous pacing?
ketamine (0.1-0.5mg/kg IV/IO)
What steps can be taken to confirm the effectiveness of transcutaneous pacing?
- identification of electrical capture
- identification of mechanical capture (palpate a pulse)
- positive waveform on the SpO2 pleth
- Improvement in blood pressure
Does the LP15 default to demand pacing, continuous pacing, or overdrive pacing?
demand pacing
What is the indication for transcutaneous pacing in bradycardic patients?
Symptomatic bradycardia unresponsive to atropine and epinephrine infusions
attempt pharmacological inteventions FIRST
You respond to a patient with DLOC and bradycardia. On assessment, you find them to be GCS=E3V4M6, BP=108/60, SpO2=97%, skin is cool and dry. You obtain the following 12-lead ecg. Describe management for this patient.
- This is a symptomatic bradycardia in context of 3rd degree AV block. The patient is symptomatic with signs of instability, but does not appear peri-arrest.
- First-line treatment is atropine, which should be attempted even if it has a low chance of success in 3rd-degree block.
- Epinephrine infusion may be attempted if patient is refractory to atropine.
- If patient does not respond to epinephrine infusion, consider procedural sedation and transcutaneous pacing.
- As with all cases of bradycardia, investigate and treat causes
You respond to a 72YO patient with DLOC. On arrival you find them to be GCS=E2V3M5, BP=68/40, HR=29BPM, SpO2=91% RA with poor pleth. Skin is ashen and diaphoretic. The patient has a history of HTN and palpitations, and was recently prescribed amiodarone for management of atrial fibrillation with RVR. What is the likely cause of their symptoms?
BRASH syndrome
You respond to a 72YO patient with DLOC. On arrival you find them to be GCS=E2V3M5, BP=68/40, HR=29BPM, SpO2=91% RA with poor pleth. Skin is ashen and diaphoretic. The patient has a history of HTN and palpitations, and was recently prescribed amiodarone for management of atrial fibrillation with RVR.
How should you treat this patient?
- This patient is peri-arrest! They are likely experiencing BRASH syndrome and will continue to decline without imminent intervention
- Epinephrine is the first line therapy. Consider push-dose epinephrine as a bridge to an epinephrine infusion
- If the patient is refractory to epinephrine, begin transcutaneous pacing (consider PSA first)
- Acquire a 12-lead ecg. If ECG changes consistent with hyperkalemia are present, consider calcium chloride, sodium bicarbonate, and salbutamol.
