In this study, we aimed to identify the predictors and outcome of cardiac arrest in paediatric patients presenting to a tertiary emergency medicine department in a LMIC. Patients with compromised circulation, bradycardia as the initial vital sign, hyperkalemia, elevated lactate levels, patients who arrived at a state of requiring oxygen therapy and intubation were the independent predictors of cardiac arrest while in the EMD. The incidence of paediatric cardiac arrest is higher than previously documented in-hospital cardiac arrest in high income countries [7, 8]. Among those who developed cardiac arrest, only 13% survived to ICU admission, which emphasizes the importance of recognizing these predictors before the arrest occurs.
In this study, bradycardia as the initial vital sign was found to be independently associated with cardiac arrest. A multicenter cohort study done in the US also found that paediatric patients with initial bradycardia had a higher likelihood of developing cardiac arrest in the EMD [9]. Bradycardia in children is known to be an ominous sign, usually associated with hypoxia and imminent cardiac arrest. This study confirms the need for early, aggressive resuscitation in children presenting with bradycardia.
In LMIC, most EMD have only a few blood-pressure cuffs for children. BP is rarely measured for young children; therefore, assessment of circulation is mainly done by evaluating the skin and mucous membranes together with the capillary refill time. Using this simple clinical assessment to determine adequacy of circulation during the primary survey, we found compromised circulation was independently associated with cardiac arrest.
Elevated blood lactate levels provide an insight into the presence of impaired tissue perfusion [10]. Lactate has been found to be a useful predictor in identifying critically ill children at high risk of death in the emergency and paediatric intensive care settings but its utility in LMICs EMDs is not as well studied [11]. We found lactate (> 2 mmol/L), done at the point of care, to be an independent predictor of cardiac arrest, suggesting it is a useful addition to physical exam. Moreover, the presence of an elevated lactate in over half of all of our patients suggests that the patients are in very late stages of disease even when they first arrive at our facility. This may be due to delayed care seeking or delays at outside facilities.
Hyperkalemia was also found to be independently associated with cardiac arrest. A previous study also noted that a high potassium level was more likely to be associated with bradycardia, reduced urine output and acidosis [12]. This combination of abnormalities signals not only an increased likelihood of cardiac arrest but also a decreased likelihood of survival [12].
Critically ill children who were hypoxic and arrived at a state of requiring oxygen therapy and intubation were significantly more likely to have a cardiac arrest. Patients who are intubated in the EMD are some of the most critically ill patients and carry a significant risk of deterioration if not intervened early. Due to the lack of sufficient ventilators and ICU beds in our setting, only the sickest children undergo intubation. Therefore, intubation is done at a very late stage in their stay at the EMD and thus carries a high risk of cardiac arrest. Similar to other studies, intubation was found to be independently associated with cardiac arrest [9, 13].
Prior studies in HICs have found that age is an important predictor of paediatric cardiac arrest where by children ≤ 5 years old are more vulnerable [14]. Literature from LMICs also suggests that the highest mortality rate in children who come to the EMD is age ≤ 5 years. In our findings, the majority of paediatric patients who developed cardiac arrest were ≤ 5 years but the difference in age was not significant between the two groups in the regression analysis. One possible explanation for this could be that the presence of other stronger risk factors masked the effect of age as a predictor of arrest.
In our study, over two-thirds of all critically ill patients were referred from other health care facilities. More patients who arrested had been referred and referral was associated with occurrence of cardiac arrest in univariate analysis, but was not an independent predictor in multivariate analysis. We suspect this is due to the fact that referral patients are more likely to critically ill and would arrive with risk factors that were shown to be independent predictors of arrest: circulatory compromise, abnormal vital signs, acidosis and need for intervention. Similar findings were obtained in a retrospective study done in Cincinnati which found that referred patients were significantly more likely to have greater severity of illness [15]. Thus delays caused by hierarchal system of referring patients could also be a contributing factor to a relatively high proportion of arrests in our EMD. Therefore, strengthening of the pre-referral care and early referral of these critically ill patients is important so as to prevent cardiac arrest.
The median duration for CPR in these children was 30 min, but in the small proportion who achieved ROSC, it was 11 min. CPR lasting ≤ 5 min was found to be one of the most important prognostic factors affecting outcome of cardiopulmonary arrest in the EMD [16]. Prolonged resuscitation of more than 15 min was associated with poor outcome during CPR [17]. This suggests that prolonged CPR in the EMD is rarely effective, and duration should be considered in determining when to stop resuscitative efforts.
Limitations
This was a single center study at a tertiary hospital. Patients at our facility may therefore have been sicker and more prone to cardiac arrest; however, it is also possible that some with cardiac arrest never reached our department. However, we see no reason to believe that the risk factors (other than perhaps referral) would be different. Also, patients were enrolled on alternate days so not all arrests were considered. Not all patients had all tests, due to the lack of availability and provider decisions.