Shock is a state of impaired tissue perfusion resulting in an imbalance between oxygen demand and supply [1]. It is an acute syndrome in which the circulatory system is unable to provide adequate oxygen and nutrients to meet the metabolic demands of vital organs [1]. Due to the inadequate Adenosine triphosphate (ATP) production to support function, the cell reverts to anaerobic metabolism, causing acute energy failure [2]. This energy failure results in the cell being unable to maintain homeostasis, the disruption of ionic pumps, accumulation of intracellular sodium, efflux of potassium, accumulation of cytosolic calcium and eventual cell death. Widespread cell death results in multi-organ dysfunction [2]. Delay in recognition and treatment of shock results in multiple organ dysfunction including central nervous system (CNS), Cardiac, Respiratory, Renal. Presence of hypotension is often a late and ominous sign of shock [3]. The cause of death in shock patients is usually from the multi-organ dysfunction [1]. It is one of the commonest causes of intensive care unit (ICU) admission and also cause of death in pediatric patients.
Depending on the cause there are five groups of shock: Hypovolemic, Septic, Cardiogenic Distributive and Obstructive shock [1].
Hypovolemic shock is the commonest type of shock in pediatric patients and it is the leading type of shock associated with mortality in developing countries, due to late presentation and the relative higher frequency of diarrheal illness in these countries [2]. Gastro intestinal (GI) fluid loss (i.e., Diarrhea, vomiting), hemorrhage, diabetic keto acidosis (DKA), diabetes insipidus are among the causes [3]. These patients present with sunken eyes, sunken fontanel, dry mucus membranes, decreased skin turgor, cool extremities, prolonged capillary refill and tachycardia [2]. Early recognition and treatment of hypovolemic shock is of paramount importance, as unrecognized and untreated hypovolemic shock can rapidly progress to cardiovascular collapse and arrest [3]. Hypotension decreased respiratory rate or apnea, decreased level of consciousness, and presence of organ dysfunction are an ominous sign in these patients [3].
Septic shock include infection, with hypothermia or hyperthermia, tachycardia (may be absent with hypothermia) and altered mental status, in the presence of at least one or more of the following: decreased peripheral pulses, prolonged capillary refill of more than 2 seconds (indicating cold shock) or flash capillary refill (indicating warm shock), mottled or cool extremities (with cold shock) and decreased urine output [2]. Septic shock is the leading type of shock among ICU admission and it is one of the leading causes of death [4, 5]. It follows body infection commonly pneumonia, primary bacteremia [4].
Cardiogenic shock in children occurs due to impaired myocardial function that results in decreased cardiac output [4]. This may be a result of impaired contractility, arrhythmias or redirected blood flow due to congenital heart disease [2]. Other causes include cardiomyopathy, myocarditis, drugs, acid–base imbalance, electrolyte imbalance, ischemic heart disease or cardiovascular surgery [2]. This type of shock is associated with hypervolemia [2].
Distributive and Obstructive shock are the less common types of pediatric shock. Effect of inadequate tissue perfusion is initially reversible but prolonged hypoperfusion results in cellular hypoxia and derangement of critical biochemical process including dysfunction of cell membrane ion pump, intracellular edema, leakage of intracellular contents, and inadequate intracellular PH regulation. This leads to irreversible cell death, multiple organ damage and then death [1].