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McCance Patho Chapter 49 quick study
Terms in this set (23)
Shock in children
is present when there are signs of poor systemic perfusion, regardless of blood pressure.
Hypovolemic shock in children
is the most common type of shock in children; it usually results from dehydration and trauma.
Hypovolemic shock also may result from expansion of the vascular space, producing inadequate intravascular volume relative to the vascular space.
**Hypotension is a sign of severe (preterminal) decompensated shock, referred to as hypotensive shock.
Clinical manifestations of hypovolemic shock:
-- include inadequate systemic perfusion associated with intravascular fluid loss.
--Adrenergic compensatory mechanisms can produce tachycardia, redistribution of blood flow, peripheral vasoconstriction, cool extremities, delayed capillary refill, and oliguria.
Neurogenic shock in children
Neurogenic shock is caused by a loss of vasomotor tone after severe injury to the spinal cord.
Clinical manifestations of neurogenic shock include warm skin, hypotension with a low diastolic blood pressure, and poor systemic perfusion. Tachycardia is not present.
Cardiogenic shock in children
with decreased cardiac output, is observed most commonly after cardiovascular surgery or with inflammatory diseases of the heart, such as cardiomyopathy and myocarditis. It is also found in children with obstructive congenital heart disease and those with drug toxicity or severe electrolyte or acid-base imbalances.
Clinical manifestations of cardiogenic shock include inadequate systemic perfusion, despite adequate intravascular volume. Cardiac output is typically low. Adrenergic compensatory mechanisms, including peripheral vasoconstriction and decreased urine volume, are similar to those found in hypovolemic shock.
Septic shock in children
Once septic shock is present, immediate treatment is urgently needed. Therapy in the first hour includes aggressive fluid resuscitation (typically 60 to 80 mL/kg administered in the first hour of therapy and approximately 200 to 240 mL/kg in the first 8 hours of therapy).
If the child does not respond to volume administration alone, vasoactive support must be initiated within the first hour of treatment.
Antibiotics also must be administered within the first hour.
Goals of therapy are to normalize the heart rate and blood pressure rapidly for age and to normalize capillary refill to less than 2 seconds.
The child's shock index ([heart rate]/[systolic blood pressure]) should fall during the first hour of management if therapy is effective. Fluid and vasoactive therapy should support high cardiac output and oxygen delivery, maintaining the S⊽o2 at approximately 70%.
Sepsis in children
Sepsis is a systemic response to infection. It is present when manifestations of SIRS are observed.
SIRS is present when the child demonstrates two or more of the following as an acute change from baseline values:
-altered heart rate
-altered respiratory rate
-alteration in the WBC count.
The newborn often develops HYPOTHERMIA rather than fever as a sign of infection and may develop BRADYCARDIA instead of tachycardia.
SIRS in children
Severe sepsis is present when there is evidence of SIRS and signs of organ dysfunction, hypoperfusion, or hypotension.
The development of septic shock is heralded when the child with severe sepsis develops signs of cardiovascular dysfunction. The child may become hypotensive despite adequate fluid resuscitation or require vasopressors to maintain blood pressure.
Reperfusion in children
Reperfusion and inflammatory injury stimulate free oxygen radicals that can damage cell membranes, denature proteins, and disrupt chromosomes. This process likely affects endothelial cells and the microvasculature, causing MODS.
Tx goals of shock in children
Lactic acidosis (rise in serum lactate level) may be the most sensitive indicator of inadequate systemic perfusion in children; effective shock therapy should eliminate lactic acidosis.
The general goals of treatment for shock are maximization of oxygen delivery and minimization of oxygen demand. This requires support of airway, oxygenation, and ventilation. Support of cardiovascular function requires support of appropriate heart rate and rhythm, adequate intravascular volume, good myocardial function, and appropriate vascular resistance and distribution of blood flow. The child should be kept warm but fever must be treated promptly.
**The signs of shock should lessen or disappear if management of shock is effective. The warmth of the child's extremities, briskness of capillary refill, quality of peripheral pulses, level of consciousness and responsiveness, urine volume, oxygenation, ventilation, and acid-base status should improve throughout shock therapy.
Burns in children
Burns in children are often the result of inadequate supervision, curiosity, inability to escape the burning agent, or intentional abuse.
Scald injuries are commonly seen in young children and result from exposure to hot water, grease, or other hot liquids, whereas flame burns are more prevalent among older children.
A child's skin is thinner and thus more susceptible to injury than adult skin. The kitchen and bathroom are common sites of burn injury.
Approximately 10% of all forms of child abuse cases in the United States result from burn injury.
Flame burns involving flammable liquids, most notably gasoline, are more common in older children. Risk-taking behaviors in young males can lead to electrical burns. Children may be exposed to chemical injury by swallowing caustic agents at home.
Rule of 9's
Use of the standard Rule of Nines results in inaccurate calculation of the percentage of TBSA in children. A modified Rule of Nines deducts 1% from the head and adds 0.5% to each leg for each year of life after 2 years of age.
Major burn trauma
Major burn trauma involves all body systems; the consequences of injury include shock, infection, hypermetabolism, organ failure, and functional limitations. These effects can be magnified in the pediatric population as a result of physiologic immaturity and age-related variation in treatment modalities.
Infection, trauma, or applying ice to the burn area may convert a partial-thickness injury to a full-thickness one, especially in young children, who have thinner, more delicate skin.
A marked reduction in cardiac output occurs immediately after injury and is accompanied by an initial increase in systemic vascular resistance. The inefficient and labile peripheral circulation of the infant complicates management of the burn shock phase of treatment.
Constriction of the chest and impairment of respiratory excursion may occur in the very young child because of the increased pliability of the rib cage. Younger children are also more susceptible to increased intra-abdominal pressure.
The leading cause of death in children after burn injury, as in adults, is inhalation injury.
Children require fluid resuscitation for smaller burns than those in adults as a result of limited physiologic reserves. Colloid replacement may be required in the very young child who fails to respond to fluid replacement.
Children younger than 2 years lack the ability to concentrate urine because of the immaturity of the renal system and are therefore at increased risk for dehydration. Because children have a relatively larger body surface area in relation to weight than adults, they require proportionately increased fluid during burn shock resuscitation to compensate for evaporative water losses.
Phases of burn physiology in children
Some children exhibit immunosuppression for a prolonged period after wound closure.
A biphasic pattern of physiologic responses is evident in the burn-injured child. The initial ebb phase occurs during the immediate postburn period and continues for 3 to 5 days.
--This phase is characterized by reduced oxygen consumption, impaired circulation, and cellular shock.
After this phase and the restoration of volume, the metabolic response shifts to a catabolic, or flow, phase.
--This phase is characterized by hypermetabolism, with increased oxygen consumption and elevation of catecholamine, glucocorticoid, and glucagon levels.
Glycogen stores are limited in children, making it hard for them to meet the increased energy demands of the burn.
--This prolonged metabolic dysfunction may lead to loss of lean body mass and increased morbidity.
Scarring in children
Although age was not found to be a predictor of hypertrophic scarring, children have greater skin tension and an accelerated rate of collagen synthesis.
Children require specialized management to ensure optimal functional and cosmetic results. Long-term scar and contracture management are necessary because of changes in body composition as the child grows and matures.
Hypotension in children in shock
In trauma with acute hemorrhage, usually 20% to 25% of blood is lost before hypotension is demonstrated. Hypotension may only occur when there is a rapid or severe loss of intravascular volume. Hypotension occurs with greater than 10% volume loss in infants and with 6% volume loss in adolescents. Hypotension is a sign of severe, decompensated shock.
Which heart rate range is associated with significantly reduced stroke volume and perfusion?
With ventricular rates of 200 to 220 bpm in infants and 160 to 180 bpm in children, stroke volume and perfusion will be reduced.
The most common sites of sepsis in children?
The most common sites of infection from these data are primary bloodstream (25%) and respiratory tract (37%) infections.
Gram-negative organisms are responsible for 40% of nosocomial infections.
Which is a true statement regarding burns in children?
Children have decreased glycogen stores and thus have difficulty meeting metabolic needs. They are unable to concentrate urine, and this inability places children at increased risk of dehydration. Children may be immunosuppressed for a prolonged period after wound closure is achieved. Children require fluid resuscitation for smaller burns as a result of their limited reserve.
What is the leading cause of death in children after burn injury?
As in adults, inhalation injuries are the most common cause of death after burn injuries. Inhalation injuries are associated with up to 80% of fire-related fatalities in the United States.
Which conditions are criteria of systemic inflammatory response syndrome (SIRS)?
SIRS is present when two or more of the following conditions are present over baseline: -fever greater than 38.5º C
-alterations in WBC count
Clinical manifestations of cardiogenic shock in children:
Cardiogenic shock is generally associated with low cardiac output.:
- The child's extremities are cool to the touch
- with delayed capillary refill despite a warm, ambient temperature
-The skin may be mottled
- Evidence of an adequate or high central venous pressure-> including hepatomegaly and periorbital edema, is typically present.
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