The updated guidelines reaffirm the importance of prevention and preparedness for a cardiac arrest in children as the first component in the chain of survival.

Newer evidence that has emerged since the last guidelines, shows that pre-arrest use of Extra Corporeal Life Support (ECLS) or Mechanical Circulatory Support (MCS) in patients with myocarditis may lead to better organ support and prevention of cardiac arrest. The survival to hospital discharge in patients with structurally normal hearts, receiving Extracorporeal Cardiopulmo-nary Resuscitation (ECPR) was 32% in adults. Myocarditis was a favorable prognostic marker for the use of ECPR in this study. Children with acute fulminant myocarditis had a 75% survival after ECLS/MCS either with recovery of native function (43.8%) or post cardiac transplant (31.3%) [2]. Retrospective analysis of the Extracorporeal Life Support Organization (ELSO) database showed a 61% survival to hospital discharge, 3% of these with heart transplantation. A recent German prospective registry showed weaning rates of 42% in children with myocarditis who received ECLS. Early transfer to ICU is also recommended for monitoring and initiation of therapy.

Type of fluid: The newer guidelines have jumped into the raging debate between balanced and unbalanced crystalloids as initial fluid of choice in septic shock. Balanced crystalloids, with a composition closer to that of normal human plasma, were postulated to reduce the incidence of hyperchloremic metabolic acidosis and acute kidney injury (AKI). A retrospective matched analysis showed better survival at 72 hours and lower rates of AKI with balanced crystalloids although another similar analysis showed no difference [3,4]. A pilot RCT, that failed to demonstrate any difference, however, established the feasibility of further research in this area. While the physiological rationale for using balanced over unbalanced crystalloids seems sound, one cannot be recommended over the other, based on the current evidence.

Volume of fluid: The updated guidelines suggest that it is reasonable to administer fluids in smaller aliquots of 10-20 mL/kg with careful reassessment for both fluid responsiveness and overload after each bolus to titrate further therapy. There is a growing inventory of evidence beginning with the FEAST Trial, warning against the perils of overzealous fluid administration in septic shock. The last AHA update in 2015 had recommended cautious fluid resuscitation in setups with limited access to intensive care resources. The current 2020 update, however, recommends it uniformly, irrespective of availability of intensive care resources. On the contrary, the Survival Sepsis Campaign (SSC) Guidelines 2020 recommend smaller volume boluses of 10-20 ml/kg, upto 40-60 mL/kg in the first hour of resuscitation, where intensive care resources are available. In settings with a lack of access to intensive care, SSC recommendations differ; in the absence of hypotension (compensated shock), fluid boluses are not recommended but if hypotension is present, 10-20 mL/kg bolus may be administered with close monitoring and utmost caution [5].

Inotropes during septic shock: It is reasonable to use either epinephrine or norepinephrine as a vasoactive infusion in septic shock. This is the first time the AHA has made such a recommendation for use of inotropes, specifically for septic shock. This is based on two important trials demonstrating superiority of epinephrine over dopamine in pediatric septic shock. The American College of Critical Care Medicine recommended use of either epinephrine or norepinephrine in septic shock depending on its ‘cold’ or ‘warm’ nature [6]. The distinctions into warm and cold shock have since been abandoned by newer guidelines [5]. Norepinephrine, however, has been found to be safe and effective as a first line agent in pediatric septic shock.

It has been seen in one prospective and 2 retrospective studies that endotracheal intubation and bag-mask ventilation (BMV) have comparable outcomes in out-of-hospital cardiac arrest (OHCA) in children [7]. Similar comparative data is however not available for in-hospital cardiac arrest (IHCA).

While formulating the previous guidelines, there was lack of evidence to support the use of respiratory rates different from those recommended in adults. Since then, newer evidence has emerged that higher respiratory rates may improve survival in children undergoing CPR, with a rider that overventilation may lead to hypotension [8]. Thus, rescue breaths should now be given at the rate of one breath every 2-3s (20-30/min) when an advanced airway is in place and while performing chest compressions.

The guidelines suggest that it may be reasonable to use cuffed over uncuffed ETT in infants and children. This is based on evidence that cuffed tubes improve ventilation and reduce the incidence of ETT changes, leading to lesser trauma [9]. Care should be given towards choosing the appropriate size and maintaining cuff pressures <20-25 cm H2O.

Contrary to the previous guidelines, which recommended routine use of cricoid pressure (unless the maneuver interferes with ventilation) in unresponsive children, the current guidelines recommend it in select cases primarily to prevent stomach insufflation. Routine use can hamper visualization during laryngoscopy and BMV. Newer data has shown that cricoid pressure during intubation and ventilation did not result in lower rates of regurgitation while decreasing success rates for first-attempt intubation.

It has been established in past guidelines that epinephrine has an important role in improving coronary and cerebral perfusion during CPR. The newer guidelines put a renewed emphasis on the timing of administration of epinephrine. Early (<5 min) administration of epinephrine from the start of chest compressions in pediatric cardiac arrest was associated with improved outcomes in multiple recent multicenter data [10,11].

It has been suggested that in patients with invasive arterial BP monitoring lines in place, it is reasonable to use diastolic BP as a guide for quality of CPR. This recommendation stems from the evidence that a DBP >25 mmHg in infants and >30 mm Hg in children during CPR was associated with greater chances of survival to hospital discharge and better neurological outcome.

Updated guidelines emphasize the importance of routine CPR protocol over naloxone use in opioid related cardiac arrest. This arises from lack of evidence for benefit of naloxone in opioid related cardiac arrest. Once CPR has been initiated as per protocol, it is reasonable to administer naloxone in suspected or confirmed opioid related cardiac arrests.

Achieving Return of Spontaneous Circulation (ROSC) is just the beginning for the healthcare providers. Following ROSC, the patient moves into the "Post Cardiac Arrest Syndrome" which includes ischemia and reperfusion injury to organs along with persisting pathophysiological derangement related to inciting trigger.

The guidelines bring into the main fold, the focused update issued in 2019 about TTM. Continuous core temperature management is recommended for post cardiac arrest patients (Both IHCA and OHCA). Hyperthermia should be strictly prevented. Either hypothermia followed by normothermia or only normothermia had similar outcomes at 1 year in 2 pediatric RCTs [12,13] and hence either may be used.

When available, continuous EEG monitoring is recommended following ROSC as evidence has shown that non convulsive status epilepticus (NCSE) is common in these children. It has also been seen that children with clinical or non-convulsive seizures following ROSC have worse outcomes. However, no recommendation has been made regarding prophylactic use of AEDs in children without clinical or non-convulsive seizures.

Certain EEG patterns have been seen to be associated with favorable (Sleep spindles, normal background, reactivity) and poor (burst suppression, flat/attenuated) outcomes but the sensitivity and specificity are not high enough to recommend use of isolated EEG for prognostication [14]. Multiple factors including but not limited to EEG, neuroimaging and biomarkers should be taken into account for prognostication. In the absence of robust data, one should avoid being dogmatic while predicting outcomes following cardiac arrest.

One of the major changes in the new guidelines is the updated chain of survival. It has been recognized that IHCA and OHCA have very different outcomes and different chains of survival have been formed for them. Both these chains now have a new sixth component which is ‘recovery’. Cognitive, neuropsychological and physical impairments continue post discharge [15]. Ongoing assessment and support following hospital discharge is essential for improving long term outcomes in these children.

Contributors: MSR,VCR: drafted the manuscript; MJ: editing, review and final approval. All authors approved the final version of manuscript, and are accountable for all aspects related to the study.

Funding: None; Competing Interest: None stated.

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