Paediatric cardiopulmonary arrest

Epidemiology

Paediatric cardiopulmonary arrests (CPAs) are a rare but devastating and often fatal events. In-hospital CPAs (IHCA) are nearly 100 times more frequent than out-of-hospital CPAs (OHCA). The incidence of IHCA is 1 per 1000 hospital patients, whereas the incidence of OHCA is 8–9 per 100,000 patient years in the paediatric population (<18years). There is also a higher incidence of CPA in the infant population of 75 per 100,000 compared with children and adolescents, who have an incidence of approximately 5 per 100,000. ^, CPAs occur in 2–6% of paediatric intensive care unit (PICU) admissions, as compared with 4–6% of post cardiac surgery intensive care unit (ICU) admissions. ^{, ,} Although survival from critical illness in paediatrics has improved significantly in recent years, improvements in survival rates from CPA have been more modest. Survival from paediatric cardiac arrest does, however, continue to improve in many (but not all) parts of the world, particularly for in-hospital occurrences.

Aetiology

The causes of CPA in the paediatric population are wide. The majority of paediatric CPAs are due to asphyxia, other causes include cardiac, respiratory illness, infections and trauma. The most common causes of OHCA are: sudden infant death syndrome (SIDS), major trauma, airway related causes, intoxication and cardiac causes. Respiratory causes are the most common, but there is considerable overlap in aetiology. Respiratory arrest may occur alone but if it is not treated promptly, may progress to cardiac arrest. ^, Many IHCAs occur in patients with preexisting chronic conditions, with the most common, causes being respiratory issues (asphyxia) and circulatory shock. Most IHCAs occur in the PICU, with CPAs approximately four times more common in the PICU than on the general paediatric ward.

Whilst the aetiology of cardiorespiratory arrest in children is diverse, the most common final pathophysiological process is progressive tissue hypoxia and acidosis due to the development of respiratory failure or circulatory shock or both. The cardiac rhythm in an arrested child is therefore usually bradycardia or asystole, reflecting the myocardial response to this final pathway of poor coronary perfusion and myocardial oxygenation. Children rarely have coronary artery disease and consequently have much lower rates of ventricular tachycardia (VT), or ventricular fibrillation (VF) compared to adults. Asystolic cardiac events are more common in OHCA, whereas bradycardic events are more common in IHCA. A systematic review of paediatric OHCA documented initial rhythms noted in 25 of the studies. Of 2734 patients, 78% had an initial asystolic rhythm, 12.8% were in pulseless electrical rhythm, 8% were in VF/pulseless VT and only 1% were bradycardic. Incidence of VF and pulseless VT rhythms are less common, occurring in approximately 20–27% of paediatric CPAs but associated with up to 41% of CPAs in post cardiac surgery patients. ^,

With most aetiologies, there are preceding symptoms and a degree of physiological compensation such as tachycardia and tachypnoea before the physiological limit of the child is reached. Once this threshold is passed, there is decompensation with bradycardia and/or respiratory arrest with subsequent loss of cardiac output. There has been considerable clinician focus in recent years on recognising and responding to deterioration before decompensation and preventing cardiac arrest in healthcare settings. Return to spontaneous circulation (ROSC) occurs in approximately 43–64% of IHCAs and is seen in approximately 30% of OHCAs.

Preventing in-hospital cardiac arrest

Given that most paediatric cardiac arrests occur in hospital, it is essential that hospital teams and systems have structures in place for education, identification, emergency management and rapid escalation of a child with acute clinical deterioration. Paediatric cardiac arrest is usually preceded by physiological deterioration before the arrest event. Being able to recognise and respond to clinical deterioration is a core skill in paediatric emergency medicine. There have been considerable efforts over the past 10 years to improve safety on wards and in emergency departments (EDs), particularly with the development of specific response teams and cognitive aids/prompts.

Medical emergency teams (METs) and rapid response teams (RRTs) have been widely adopted by many healthcare systems with the aim to intervene and treat the deteriorating patient and to prevent CPA. These formal MET and RRT systems require significant resources and training, and can be expensive to implement. There is variability across institutions regarding the structure of MET/RRT, with each institution establishing their own MET/RRT based on the personal and skill sets available to them. There is no standard, evidence-based physiological triggers for activation of a MET or RRT, so hospitals develop their own criteria, usually based on patient vitals (physiological changes) and mental state (behavioural changes), but a MET/RRT can also be activated by worried staff. Many available hospital aids include and focus on the recognition of early clinical deterioration in children. One such system adopted by many healthcare systems is the paediatric early warning system (PEWS), which allows for periodic review of a child’s physiological parameters, assigns numeric scores to specific abnormal observations and has predetermined criteria for communication and escalation of care in response to clinical decline. A systematic review in 2017 studied the effectiveness of different PEWS detection systems, the effectiveness of PEWS response systems and the evidence that exists on PEWS implementation strategies/interventions. There was not conclusive evidence for the effectiveness and impact of PEWS in clinical practice. There was significant heterogenicity in the PEWS tools and the tools did not have high specificity and sensitivity. However, the paper did report evidence suggesting improved clinical outcomes (e.g., reduced CPAs, earlier intervention, and transition to PICU). Other strategies of systematically detecting early clinical deterioration include colour-coded, age-specific, vital-sign-observation charts that visually identify physiological parameters in a predefined range of clinical concern.

EDs in many jurisdictions have implemented paediatric clinical deterioration recognition and response systems. PEWS can be used in the emergency department to identify those who may need admission or more intense care. A prospective study of 12,306 patients found that an elevated PEWS at initial assessment in the ED was associated with the need for admission directly to the PICU. Another study found that a PEWS >3 was specific but not sensitive in predicting hospital admission and was specific but not sensitive for predicting significant illness in the paediatric ED.

The impact of MET and RRT on rates of cardiac arrest have been difficult to assess due to the observational nature of studies, low frequency of cardiac arrests, and confounding variables, such as concomitant clinical system improvements. ^, However, a systematic review in 2015 looked at RRTs and their impact on hospital mortality, non-ICU CPAs and ICU admission rates. The study showed that RRTs are associated with a reduction in hospital mortality (RR 0.82, 95 % CI 0.76–0.89) and cardiopulmonary arrests (RR 0.65, 95 % CI 0.61–0.70, P <0.001) in the paediatric population.

The International Liaison Committee on Resuscitation (ILCOR) guidelines recommend the institution of MET/RRT with a very weak supporting level of evidence. The guideline places significant and greater emphasis on the ability to recognise and respond to deteriorating illness rather than mandating a formal MET/RRT structure.

Outcome

The outcomes from respiratory arrest alone are more favourable than cardiorespiratory arrest. CPA is a multifactorial process and there are factors which affect outcomes in the pre-, intra- and postarrest phases. In the in-hospital prearrest period, the activation of the MET and RRT team is important to try to prevent CPA. However, some children have preexisting medical conditions, such as cardiac arrhythmias, which increase their likelihood of having a CPA and may influence their outcome.

Paediatric cardiac arrest situations place huge amounts of stress on the resuscitation rooms in which they are being managed. The workplace becomes an even more hectic environment than normal, with increased levels of audio-visual stimulations, coupled with the emotional demands placed on teams, particularly when parents are present during the resuscitation itself. Factors which can occur during the arrest and may be associated with poor outcomes include but are not limited to:

• hyperventilation which can impair venous return to the heart directly affecting cardiac output

• lack of bystander cardiopulmonary resuscitation (CPR)

• prolonged resuscitation (>15 minutes) with administration of great than three doses of epinephrine ^{, ,}

• a nonshockable rhythm

Optimisation of postarrest care involves the prevention of persistent hyperglycaemia, hyperthermia and hypotension which are associated with poor results.

Survival rates in paediatric CPA varies throughout the literature, with some documenting survival rates in up 40% of patients. The American Heart Association’s get with the guidelines–resuscitation (GWTG-R) registry is a large multicentre registry of in-hospital cardiac arrests. Between January 2000 and December 2012, 12,404 IHCA events were registered with the GWTG-R, across 354 centres. Analysis concluded that 36.2% of the patients survived to hospital discharge. A prospective study of IHCA in Melbourne showed that 36% of these patients survived to discharge.

The cardiac arrest registry to enhance survival (CARES) reports data on OHCAs in the United States. Data obtained between October 2005 and December 2013 included 1980 patients, with 8.2% of the patients surviving to hospital discharge. Similar figures were seen in Melbourne, Australia over a 7.5 year period. Of 193 children with OHCA, 7.7% of these survived to discharge. A systematic review of 5363 OHCA showed a survival to hospital discharge of 12%.

There is lack of reliable data on neurological outcomes of children post CPA but favourable neurological outcome rates decrease with increased CPR duration. Neurological outcomes may be influenced by the cause of arrest, the adequacy of CPR performed, the duration of no-flow (no CPR) and the time lapsed to restoration of blood flow. Additional factors may include oxygen content and ventilation following ROSC, injury secondary to ischaemia–reperfusion injury, and postarrest management.