Posted by American Heart Association, Inc. on Jan 11th 2020

​Pediatric Advanced Life Support - PALS Core Testing Case Scenario 9: Supraventricular Tachycardia (Adolescent; Unstable)

Pediatric Advanced Life Support - PALS Core Testing Case Scenario 9: Supraventricular Tachycardia (Adolescent; Unstable)

Scenario Lead-in

Prehospital: You are dispatched to a house where a 12 year old boy has lethargy, tachypnea, and a racing heart.

ED: An ambulance is en route to the emergency department with a 12 year old boy with lethargy, tachypnea, and a racing heart.

General Inpatient Unit: You are called to examine a 12 year old boy with lethargy, tachypnea, and a racing heart.

ICU: You are called to the bedside of a 12 year old boy who says he has a racing heart now and has lethargy

Vital Signs:

Heart rate: 235/min

Blood pressure: 75/55 mm Hg

Respiratory rate: 34/min

Spo2: 92% on room air

Weight: 50 kg

Age: 12 years

Scenario Overview and Learning Objectives

Scenario Overview: Emphasis should be on diagnosis and management of supraventricular tachycardia (SVT) in an unstable patient, including possible rapid bolus administration of adenosine (only if intravenous IV/intraosseous IO access is readily available) and the safe delivery of synchronized cardioversion using appropriate doses. Vagal maneuvers may be performed while preparing adenosine or while preparing for synchronized cardioversion but should not delay intervention. If time allows, the instructor may briefly discuss the need for expert consultation before administering a precardioversion sedative to a child with hemodynamic instability.

Scenario -Specific Objectives

Differentiates between SVT and sinus tachycardia; In this scenario, the child has instable SVT

Describes potential vagal maneuvers used for a child with SVT; potential maneuvers used in children include blowing through an obstructed straw and carotid sinus massage

Demonstrates the proper rapid bolus technique to administer adenosine

Discuss indications for synchronized cardioversion; in this scenario, the child has poor perfusion, including hypotension, acutely altered mental status (new lethargy), and signs of shock

Demonstrate safe delivery of synchronized cardioversion with appropriate dose in a patient with SVT and poor perfusion

Evaluate - Initial Impression (Pediatric Assessment Triangle)

Appearance: Moaning, minimal response to caregivers

Breathing: Increased rate and effort, including nasal flaring

Circulation: Pale and mottled


Immediate intervention needed


Activate the emergency response system. Emergency medical services requests additional assistance if needed. Administer 100% oxygen by norebreathing face mask Apply cardiac monitor Apply pulse oximeter

Evaluate - Primary Assessment

Focused on Assessment Needed to Support Airway, Oxygenation, Ventilation, and Perfusion

Airway: Clear

Breathing: Respiratory rate 34/min; Spo2 92% before supplementary oxygen and 100% after; crackles throughout lung fields

Circulation: Heart rate 235/min; weak central pulses, thread peripheral pulses; cool/mottled skin; capillary refill about 6 seconds; blood pressure 75/55 mm Hg

Disability: Deferred until after successful rhythm conversion

Exposure: Temperature 37.6 C (99.7 F)

Weight: 50 kg


Altered level of consciousness

Narrow complex tachycardia/SVT with a pulse and poor perfusion

Respiratory distress vs respiratory failure

Hypotensive shock


Establish IV/IO access if possible but do not delay cardioversion if IV/IO access is not readily available.

Guide child to perform vagal maneuvers if they do not delay adenosine or cardioversion

If functional IV is in place or is established immediately, administer adenosine

-Begin recording continuous rhythm strip.

-Give adenosine 0.1 mg/kg (max 6 mg) IV/IO by rapid bolus followed by rapid saline flush.

-If first dose of adenosine is unsuccessful, administer adenosine 0.2 mg/kg rapid bolus (max 12 mg), if it can be given more rapidly than synchronized cardioversion. Ensure that rapid bolus technique is used to administer the drug.

-If adenosine is ineffective, provide immediate synchronized cardioversion.

Deliver synchronized cardioversion as soon as it is available, unless other therapies (eg, adenosine) have worked by the time synchronized cardioversion can be delivered. (Note: Don not delay cardioversion to attempt other therapies if synchronized cardioversion can be provided immediately)

-If functional IV/IO access and expertise is immediately available, provide sedation before cardioversion if it won’t delay cardioversion. Use caution; expertise is required toa void worsening hemodynamic instability.

-As soon as a monitor/defibrillator arrives, attach pads and begin recording the rhythm strip

-“Clear” and perform synchronized cardioversion (0.5 to 1 J/kg,)

-If Synchronized cardioversion is unsuccessful, “clear” and perform synchronized cardioversion with 2 J/kg.

Prepare to assist ventilation (with bag mask device) if needed.

Evaluate - Secondary Assessment

Deferred Until After Rhythm Conversion

SAMPLE history

Signs and symptoms: Tachycardia; lethargy; hypotension

Allergies: None known

Medications: None

Past medical history: History of SVT about 4 years ago

Last meal: 6 hours ago

Events (onset): Acute onset 30 minutes ago

Physical examination:

Repeat vital signs after successful rhythm conversion: Heart rate 104/min; sinus rhythm; respiratory rate 28/min; Spo2 100% on 100%oxygen by nonrebreathing mask; blood pressure 100/60 mm Hg

Head, eyes, ears, nose and throat/neck: Clear; no audible breath sounds

Heart and lungs: Sinus rhythm; central and peripheral pulses strong; capillary refill 3 seconds; no murmur, gallop, or rub appreciated; fine scattered crackles at bases on auscultation

Abdomen: Liver not palpable below the costal margin

Extremities: Cool peripherally

Back: Unremarkable

Neurologic: Cries out in pain with cardioversion; opens eyes and moves spontaneously, answering words or short phrases

Point-of-care (POC) glucose concentration (see below)

If no rhythm conversion or delay in administering adenosine or cardioversion

Vital signs: Heart rate 235/min; weak central pulses, peripheral pulses barely palpable; cool/mottled skin; capillary refill about 6 seconds; respiratory rate 34/min; Spo2 93% despite 100% oxygen via nonrebreathing mask; crackles throughout lung fields; blood pressure 72/54 mm Hg


SVT with poor perfusion converts to sinus rhythm if rapid adenosine or cardioversion is provided


After rhythm conversion

-Reassess and monitor patient’s cardiorespiratory status

*Evaluate for signs of heart failure (enlarged live, extra heart sounds or murmurs, crackles, rales).

-Prepare to insert advanced airway if needed.

-Wean supplementary oxygen as tolerated if child stabilizes

-Obtain 12 lead electrocardiogram (ECG)

-Check glucose with POC testing

Evaluate - Diagnostic Assessments

Perform Throughout the Evaluation of the Patient as Appropriate

Lab data

Blood glucose



Chest x-ray, 12 lead ECG in SVT and in sinus rhythm


Although laboratory test are generally not appropriate during the immediate management, a blood glucose concentration should be checked as soon as reasonably possible in critically ill infants and children. Hypoglycemia should be treated immediately.

Laboratory studies (other than POC glucose testing) are deferred until rhythm is converted and systemic perfusion and hemodynamic function are improved.