(PALS) Pediatric Shock Overview – Part 2
General Recognition of Pediatric Shock:
Early management and reversal of shock is associated with improved outcomes. However, early management is dependent upon early RECOGNITION of shock at the bedside.
Failure to recognize the signs and symptoms of shock results in delayed treatment and higher mortality rates.
Signs and symptoms of the pediatric shock state have to do with compensatory changes that occur in the body when there is an attempt to increase cardiac output (i.e. oxygen delivery to the tissues)
Because of the vast array of disorders that can cause shock in the critically ill child, the signs and symptoms that comprise shock can be varied. In spite of this, there are a few common early signs and symptoms which generally indicate that shock may be present.
Early recognition of pediatric shock requires a proper understanding of compensatory mechanisms that are involved in maintaining oxygen delivery to the vital organs.
Remember that cardiac output = stroke volume x heart rate. The first observable physiologic action that occurs when the body attempts to maintain cardiac output is to increase the heart rate. When this occurs, tachycardia is present.
The effect of tachycardia for improving cardiac output is limited because as heart rate increases, the cardiac filling time shortens. This can ultimately lead to a decrease in cardiac output.
Increased Systemic Vascular Resistance (Vasoconstriction):
When there is a compromise in oxygen delivery to the body’s tissues and organs, the compensatory mechanisms attempt to maintain adequate oxygen delivery to the vital organs by vasoconstriction which causes a reduction of blood flow to non-vital tissues such as skin, kidneys, and intestines.
This compensatory mechanism of vasoconstriction can present as slowed capillary refill, cool, pale, and mottled skin and weak peripheral pulses. Vasoconstriction in the kidneys results in decreased urine output.
There can also be an increase in smooth muscle tone which helps to improve blood flow back to the heart and results in improved preload.
Increased Cardiac Contractility:
When there is compromised oxygen delivery to the body’s tissues, the heart can also increase contractility so that there is a more complete emptying of the left and right ventricles.
When there is compromised oxygen delivery to the tissues and shock is present, compensatory mechanisms cause certain changes in blood pressure that can provide clues to the presence of shock.
In children, the compensatory mechanism of increased systemic vascular resistance can be very effective at maintaining systolic blood pressure. However because of the increase in systemic vascular resistance diastolic pressure is typically elevated. This causes a narrowed pulse pressure which is the difference between the systolic and diastolic blood pressure.
Remember: Blood pressure may remain normal and a critically ill child may still have signs of shock. However, it is likely that there will be a narrowed pulse pressure.
Systolic blood pressure alone is not a good early indicator of pediatric shock because of the presence of highly effective compensatory mechanisms.
When hypotension develops in the pediatric patient with shock, this is a sign that compensatory mechanisms are no longer effective for maintaining cardiac output. This is an ominous sign and can be an indication of impending cardiac arrest.
Below is a formula for determining adequate systolic blood pressure in children ages 1 to 10.
[2 x (age)] + 70] = low limit for an acceptable SBP
The progression of shock is unpredictable in the pediatric population, and observing for changes in signs and symptoms can help detect shock progression. This is critical for the early detection and treatment of shock. Below is a list is of common signs and symptoms of deterioration with pediatric shock.
Worsening tachycardia, continued narrowing of the pulse pressure, changes in level of consciousness, weakening central pulses, and hypotension which is a late sign.
The signs and symptoms listed above will become progressively worse if shock is not recognized and treated early. It is important to monitor for changes in symptoms that indicate further deterioration.
Go to Pediatric Shock Overview Part 3