Arrhythmias in Children : NEET SS Pediatrics

Pediatric Cardiac Arrest Algorithm

What Is Cardiac Arrest?

• It is the cessation or stoppage of blood circulation due to absent or ineffective cardiac function. Cardiac arrest is associated with absent pulses for both central and peripheral counterparts. Cardiac arrest can often produce loss of consciousness and absent breathing or gasping efforts by the patient suffering from cardiac arrest. 

Mechanism Of Cardiac Arrest 

• The mechanisms of cardiac arrest can be broadly divided into two parts, and they are:

1. Asphyxial Hypoxic Mechanism
   • Initially, an event causes tissue hypoxia in the body and produces metabolic acidosis. Due to this hypoxia, there is depression in the cardiac functions, which causes cardiac arrest.  This is a more common mechanism seen in children (compared to adults) in cases such as septic shock.
2. Sudden Cardiac Arrest
   • In such a case, something will happen which will suddenly cause the heart to stop.  There is no hypoxia in such a condition. This is seen less commonly in children and is mostly seen in adults. Sudden cardiac arrest is associated with a diseased heart.  It can be associated with conditions that stand to produce ventricular fibrillation, arrhythmias and acute emergencies. 

Changes In Pals 2020 Edition (Compared To The 2015-16 Edition)

Major Change

1. Early use of epinephrine has been stressed in a non-shockable rhythm after starting CPR. Comparing both protocols, it can be seen that after starting CPR, when there is a cardiac arrest, one usually checks if it is a shockable rhythm or a non-shockable rhythm. If it was a non-shockable rhythm initially, the concept was that CPR would be carried out, during which epinephrine would be given. But the most recent changes state that after CPR has been initiated and if it is a non-shockable rhythm, epinephrine needs to be given as soon as possible, followed by the other steps.  Early use of epinephrine has been emphasized.

Subtle Changes

• There has been explicit mention of starting BMV during CPR. If the rhythm becomes shockable in asystole/PEA, a subtle change has happened in the step where defibrillation shock is to be given.

Protocol For Cardiac Arrest

• If a child comes with paediatric cardiac arrest, CPR must first be started. BMV, oxygen supply, and attachment to monitor or defibrillator have to be first taken care of. The next step is to check whether the rhythm is shockable or not.  If the rhythm is shockable, there are two possibilities.  It is either ventricular fibrillation or it is pulseless ventricular tachycardia. First, shock is given to the patient, immediately after which CPR has to be started for 2 minutes, and IV/IO access must also be taken.  It has to be checked again if the patient has a shockable rhythm. If yes, a second shock is given to the patient. CPR is again given for 2 minutes. Epinephrine is to be given every 3 to 5 minutes. The advanced airway can also be considered. 
• The rhythm has to be checked for being shockable or not. If yes, the third shock is given to the patient, and CPR is continued for 2 minutes. Amiodarone and lidocaine have to be considered along with the treatment of reversible causes.  The continuity of checking for shockable rhythm has to be carried on.  If the rhythm is non-shockable at any stage, two things have to be considered: If there is no return of spontaneous circulation, the patient has to be treated as having asystole.  If there is a return of spontaneous circulation, post-arrest care has to be given. 
• If the rhythm is non-shockable in the first step, it has to be considered that the patient has an asystole or a pulseless electrical activity. In these patients, epinephrine injection is administered as soon as possible. CPR is then given for 2 minutes.  IV/IO access is the next step. If not previously obtained, epinephrine has to be continued every 3-5 minutes and advanced airway has to be considered.  One has to check if the rhythm is shockable or not after this stage. If the rhythm is shockable, shock will be given to the patient. If the rhythm is not shockable, CPR is given for 2 minutes, and treatment of the reversible causes is to be carried on. 
• One has to again check if the rhythm is non-shockable, two things have to be considered: If there is no return of spontaneous circulation, the patient has to be treated as having asystole.  If there is a return of spontaneous circulation, post-arrest care has to be given. If the rhythm is shockable, One has to go to step 7, that is, shock, CPR for 2 mins, and Amiodarone and lidocaine have to be considered along with the treatment of reversible causes.

CRP Quality

• These are the steps that are to be adhered to: One has the push hard (> or = 1/3rd APD) and fast (100-120/min) and allow recoil.  One has to minimise interruptions. One has to change the compressor every 2 minutes or if fatigued.  If there is no advanced airway, C: V is to be in the ratio of 15:2. If there is an advanced airway, there have to be continuous compressions and a breath should be given every 2 to 3 seconds.

Shock Energy For Defibrillation

• The first shock should be 2 J/kg. The second shock should be 4 J/kg. The subsequent shocks should be > or = 4 J/kg, maximum up to 10 J/kg or adult dose. 

Drug Therapy

• Epinephrine IV/IO dose is to be 0.01 mg/kg (0.1 ml/kg of solution with 0.1 mg/ml). The maximum dose is 1 mg, which can be repeated every 3 to 5 minutes. If no IV/IO route is available, one has to give an endotracheal dose of 0.1 mg/kg. Amiodarone IV/IO dose is to be given at 5 mg/kg bolus and can be repeated for a maximum of 15 mg/kg. Lidocaine IV/IO dose is to be given at 1 mg/kg loading dose. 

Advanced Airway

• One can opt for endotracheal intubation or supraglottic advanced airway.  To confirm ET placement, one can perform waveform capnography or capnometry. 

Also Read: Pulmonary Hypertension : Epidemiology, Pathology, Classical Features, Investigations, Treatment And Prognosis

Reversible Causes Of Pediatric Cardiac Arrest

• 6 H's and 5 T's.
  • Hypovolemia.
  • Hypoxia.
  • Hydrogen ion (acidosis).
  • Hypo-/hyperkalemia.
  • Hypothermia.
  • Tension Pneumothorax.
  • Tamponade cardiac.
  • Toxins.
  • Thrombosis (pulmonary circulation).
  • Thrombosis (coronary circulation).

Pediatric Bradycardia With A Pulse Algorithm

• Paediatric bradycardia is a slow heart rate for age and level of activity in a child. It can be a sign of impending cardiac arrest. Significant bradycardia is when there is bradycardia and cardio-pulmonary compromise in the patient.  Shock, altered sensorium, or hypotension can be included in cardio-pulmonary compromise. This can be of two types:  Primary pediatric bradycardia: Which relates to problems in the heart itself. Secondary pediatric bradycardia: This is caused by secondary causes that lie outside the heart, for example, CNS tumor. 

Protocol

• When a patient has pediatric bradycardia- One has to first check for the presence of cardio-pulmonary compromise.  If the answer is no, one has to support the airway breathing circulation. The child will be observed, oxygen will be supplied to the child, a 12-lead ECG will be performed, and investigation and treatment of the cause will also be carried out. When cardiopulmonary compromise is present, assessment and support have to be carried out. A patent airway has to be maintained first. A positive pressure ventilation/oxygen mask/or both can be used.  Cardiac monitoring such as pulse, BP and SPO2 have to be carried out. 
• If the heart rate is below 60 per minute despite PPV and O2, CPR has to be started. If bradycardia persists in such patients, CPR has to be continued. IV/IO access has to be obtained; epinephrine is to be given to the child. In addition, atropine and transvenous or transthoracic pacing is to be considered if there is a block or presence of hyper vagal responses in the child.  The underlying causes is to be treated. The pulse is to be checked every 2 minutes. If the pulse is absent, it is to be treated as cardiac arrest.  If bradycardia improves, one has to support airway breathing circulation. 

Drug Therapy In Bradycardia

• Epinephrine is given in IV/IO dose, the same as given in cardiac arrest. 
• Atropine is given in IV/IO dose of 0.02 mg/kg. This may be repeated once. A maximum dose of 0.1 mg and a minimum possible dose of 0.5 mg can be given. 
• Possible causes of pediatric bradycardia.
  • Hypothermia.
  • Hypoxia.
  • Medications.

Also Read: Aneuploidies Including Turner And Klinefelter Syndrome

Pediatric Tachycardia With A Pulse Algorithm

Changes In PALS 2020 Edition

Major Change

• A single algorithm was introduced to cover both narrow complex and wide complex tachycardias in pediatric patients.

Protocol

• When a child comes in with pediatric tachycardia: Initial assessment and support are carried out by maintaining a patent airway and supporting breathing if needed. Oxygen supply can then be started for the child. Cardiac monitoring is carried on for the child (checking for BP, HR, and SPO2). IV/IO access is maintained. 12-lead ECG is carried out if available. After this, the rhythm is evaluated with ECG or a monitor. There are two possibilities: The child may have sinus tachycardia, with the heart rate being less than 220 in infancy and less than 160 in cases of older children. There are normally present P waves and variable RR intervals in cases of sinus tachycardia. One can identify and treat the cause of sinus tachycardia in such a condition.  In case there are no signs of sinus tachycardia, one must look for cardiopulmonary compromise.
• If the cardiopulmonary compromise is present or absent, one will check for QRS duration.  If the cardiopulmonary compromise is present, then the QRS duration might be a narrow-complex QRS (< or = 0.09 sec) or a wide-complex QRS (> 0.09 sec). If narrow-complex QRS is present, there is a probability of supra ventricular tachycardia in the patient (heart rate more than or equal to 220 in case of infants; heart rate more than or equal to 180 in case of older children; P waves will be absent or abnormal; RR interval will show lack of variability; there will be a history of abrupt change in the heart rate).  In such patients, in case IV/IO access is present, adenosine will be the drug of choice.  In such patients, in case IV/IO access is not present, adenosine will be the drug of choice. If adenosine fails, synchronized cardioversion will be given.  If wide-complex QRS is present, there is a probability of ventricular tachycardia in the patient. Synchronized cardioversion will be given to these patients.
• If cardiac-pulmonary compromise is not present, QRS duration has to be checked for narrow (< or = 0.09 sec) and wide complex (> 0.09 sec). If it is a narrow complex, SVT is probable (same features as discussed above). For probable SVT, because there is no compromise, one can try vagal manoeuvre (done by applying an ice pack to the child; applied on the upper half of the face, just above the nostrils). During this, pressing the eyeballs of the child is completely contraindicated as it can cause retinal damage. If there is no improvement in the patient after this, one can consider IV/IO access or adenosine.  In the case of wide-complex QRS, one is possibly looking at VT. If the rhythm is regular with monomorphic QRS, adenosine or cardiology consultation will be considered in such a patient.

Therapy In Tachycardia

• Synchronised cardioversion is carried out. One may begin with 0.5-1 J/kg. If not effective, it may be increased to 2 J/kg. Sedation is to be carried out if needed, but cardioversion cannot be delayed.  Adenosine IV/IO dose can be given with 0.1 mg/kg rapid bolus (maximum 6 mg) and the second dose being 0.2 mg/kg rapid bolus (maximum 12 mg).

Also Read: Infections of the Upper Airway- Common Cold and Sinusitis

Hope you found this blog helpful for your NEET SS Pediatrics Cardiology preparation. For more informative and interesting posts like these, keep reading PrepLadder’s blogs.