Extra Topic 6.6 -- PALS

Question 1

You are checking on the child in the postoperative unit, when her heart rate suddenly speeds up to 190 bpm. What would you do?

(You provide anesthesia for a 2-year-old female for bilateral myringotomy tube placement.)

Answer 1

Assuming she were hemodynamically stable and that I believed this to be supraventricular tachycardia

(i.e. heart rate > 180 bpm in a child, absent or abnormal P-waves, and/or a history of abrupt rate changes),

I would first apply supplemental oxygen and attempt to convert her arrhythmia with a vagal maneuver, such as applying ice to her face.

If this were ineffective, I would establish intravenous access and administer 0.1 mg/kg of adenosine in an attempt to interrupt any reentry circuit involving the atrioventricular node (the usual cause of SVT in children) by temporarily blocking conduction through the atrioventricular node.

If her SVT persisted or reoccurred, I would give successive doses of 0.2 and 0.4 mg/kg every 1-2 minutes, as necessary.

At the same time, I would ensure adequate monitoring (i.e. ECG, blood pressure cuff, pulse oximeter), secure her airway (preferably an ETT), prepare for cardioversion in case the patient became unstable, and treat any possible contributing factors, especially hypoxia.

Clinical Note:

• Contributing factors that should be identified and treated during cardiopulmonary resuscitation of a pediatric patient with an arrhythmia include:
  
  • Hypovolemia
  • Hypoxia
  • acidosis (Hydrogen ion)
  • Hypo-/hyperkalemia
  • Hypoglycemia
  • Hypothermia
  • Toxins
  • cardiac Tamponade
  • Tension pneumothorax
  • Thrombosis
  • Trauma (hypovolemia)

Question 2

The vagal maneuver is unsuccessful and you do not have intravenous access. What would you do?

(You provide anesthesia for a 2-year-old female for bilateral myringotomy tube placement.)

Answer 2

Assuming she remained hemodynamically stable, I would make a quick attempt at obtaining peripheral intravenous access.

If I were unable to quickly achieve this, I would immediately insert an interosseous needle into the anterior surface of her tibia (1-2 cm below and 1 cm medial to the tibial tuberosity).

While an interosseous line provides good access for the administration of all fluids and medications routinely given during cardiopulmonary resuscitation, it is also associated with several complications, such as – osteomyelitis, fat and bone marrow embolism, and compartment syndrome.

Therefore, I would view this as a temporary solution until a more definitive intravenous line could be placed.

Question 3

Would you give adenosine through a peripheral line?

(You provide anesthesia for a 2-year-old female for bilateral myringotomy tube placement.)

Answer 3

While central line access may be preferable due to the rapid metabolism of adenosine by red blood cell adenosine deaminase (half-life = 10 seconds), I would administer it through a peripheral line if necessary.

However, given its rapid metabolism, I would quickly flush the peripheral line with 10 mL of saline following drug administration.

Question 4

Before you have a chance to establish intravenous access of any kind, her heart rate increases to 260 bpm and her blood pressure drops precipitously.

What would you do?

(You provide anesthesia for a 2-year-old female for bilateral myringotomy tube placement.)

Answer 4

In the setting of supraventricular tachycardia and hemodynamic instability,

I would prepare for immediate synchronized cardioversion, beginning at 0.5 J/kg and doubling the energy dose as required up to 2 J/kg.

While cardioversion was being prepared, I would secure her airway, apply 100% oxygen, and attempt to place an interosseous line (in the setting of hemodynamic instability, time should not be wasted attempting to obtain intravenous access, which may prove more difficult secondary to poor peripheral perfusion).

However, given the urgency of converting her arrhythmia, I would not delay cardioversion for intravenous access.