Intravenous (IV) fluid management isindicated as the first therapeutic intervention for all types of shock
Intravenous (IV) fluid management isindicated as the first therapeutic intervention for all types of shock: Excerpt from Avoiding Common Pediatric Errors
Author:
Caroline Rassbach, MD
What to Do - Take Action
Shock occurs when the oxygen and nutrient supply is insufficient to meet the
metabolic demands of the body. Shock can be classified as hypovolemic, septic, distributive, and cardiogenic. Hypovolemic shock is the most common
type of shock in children. It is usually the result of fluid-losing states such as
diarrhea, blood loss, or burns. The effect is decreased intravascular volume,
decreased preload, and decreased stroke volume. When hypovolemic shock
occurs as a result of fluid and electrolyte losses, both intravascular and interstitial fluid volume is decreased. Physical signs are classic for dehydration,
including sunken eyes, depressed fontanelle, dry mucous membranes, cool
extremities, decreased peripheral pulses, and poor skin turgor. In contrast,
patients with hypovolemic shock because of increased capillary permeability have intravascular hypovolemia with interstitial euvolemia. Such is the
case with burns and nephrotic syndrome. Physical signs include mental
status changes, increased capillary refill, decreased peripheral pulses, and
decreased urine output without the classic signs of dehydration. Extremities
may be edematous. Treatment of hypovolemic shock consists of replacement
of fluids. When shock is secondary to blood loss, fluid replacement should
include blood products.
Septic shock occurs as a consequence of bacterial, fungal, or viral infection. It is defined as hypotension despite adequate fluid resuscitation and
inadequate perfusion. Signs of inadequate perfusion may include lactic acidosis, oliguria, or altered mental status. In children, septic shock can present
as classic "warm shock," with high cardiac output and low systemic vascular
resistance,oras"coldshock"withdecreasedcardiacoutputandelevatedsystemic vascular resistance. Septic shock should be treated with IV fluids and
broad-spectrum antibiotics. Following resuscitation with at least 60 mL/kg
of isotonic fluid, vasopressors may be required to maintain blood pressure.
In addition, cortisol replacement may be indicated if adrenal insufficiency
occurs.
Distributive shock, also known as vasodilatory shock, occurs because
of abnormal regulation of blood flow, resulting in functional hypovolemia.
One example of distributive shock is anaphylactic shock, a hypersensitivity
reaction that occurs immediately after exposure to an allergen. The result is
animmunoglobulin(Ig)E-mediatedmassivereleaseofcytokinesbymastcells
and basophils. Angioedema, hypotension, and third-spacing ensue and can
be life-threatening. Immediate treatment with subcutaneous epinephrine, as
well as fluid resuscitation, is imperative. In addition, airway management
and treatment with antihistamines and steroids are required.
Another example of distributive shock is neurogenic shock, which results from injury to the central nervous system (CNS). Neurogenic shock
is usually transient and occurs after an acute injury to the CNS. There is
generalized loss of sympathetic vascular and anatomic tone. Cardiac contractility is preserved and can usually increase to maintain cardiac output
without raising the heart rate. Eventually, however, cardiac output may be
compromised by lack of venous return. As a result, neurogenic shock may
demonstrate hypotension in the absence of tachycardia. Treatment includes
volume resuscitation and vasopressors.
Cardiogenic shock is the last major category of shock and results from
cardiac abnormalities that cause decreased myocardial contractility, arrhythmias,leftventricularoutflowtractobstruction,andlargeleft-to-rightshunts.
With cardiogenic shock, fluid resuscitation should be judicious, as the patient may present in fluid overload or in volume depletion. Vasopressors and
inotropes may be beneficial.
In both septic shock and distributive shock, a low systemic vascular
resistance is the primary problem. In contrast, in hypovolemic shock and
cardiogenic shock, the primary problem is a reduced cardiac output. The
earliest physical sign of all types of shock is tachycardia. The heart rate
and stroke volume increase to sustain cardiac output. Systemic vascular
resistance is also maximized to maintain blood pressure. This is accomplished by diverting blood from less essential organs, such as the skin, kidneys, and skeletal muscles, to essential organs, such as the brain, heart,
lungs, and adrenal glands. In the early stages of shock, also known as
compensated shock, blood pressure is maintained as a result of this diversion, but blood flow to the less essential organs is compromised. Physical signs to evaluate for shock should include heart rate and end-organ
perfusion, such as capillary refill, urine output, mentation, and peripheral
pulses.
With all types of shock, the blood pressure drops only after the body
maximizes heart rate and systemic vascular resistance. At this point, the
patient may rapidly decompensate, as vital organs no longer receive the
oxygen and nutrients they need. Hypotension represents an advanced stage
of shock, known as decompensated shock, and has a high mortality rate.
Multisystem organ failure and death may result.
Practitioners must recognize early signs of shock to initiate treatment
and prevent morbidity and mortality. Patients should be treated initially according to the ABCs: airway stabilization,oxygen therapy, and establishment
of vascular access. Large-bore peripheral IV lines, intraosseous lines, or central venous catheters are required. Fluid resuscitation should begin with a
20 mL/kg bolus of isotonic crystalloid. Fluid status should be reassessed
and the need for subsequent therapy considered, including further IV fluids, pressors, or antibiotics. If the patient does not have cardiogenic shock,
boluses may be repeated up to 60 to 80 mL/kg in the first 1 to 2 hours. The
patient should be closely monitored for signs of fluid overload. In the absence of renal disease, urine output of 1 to 2 mL/kg/hr is a useful indicator
of adequate organ perfusion.
In summary, all categories of shock have similar physical manifestations
and a common endpoint. Physical signs present in all types of shock include
tachycardia and poor perfusion to end organs. In addition, the initial treatment for all types of shock is also the same and includes resuscitation with
intravenous fluids.
Suggested Readings
Frankel LR and Mathers LH. Shock Chapter 57.2. In: Behrman RE. Nelson Textbook of Pedi
atrics, 17th ed. Philadelphia: WB Saunders; 2004.
McKiernan CA, Lieberman SA. Circulatory shock in children: an overview. Pediatr Rev.
2005;26(12):451–460.
Book Source Details
- Book Title: Avoiding Common Pediatric Errors
- Author(s): Anthony D Slonim MD, DrPH; Lisa Marcucci MD
- Year of Publication: 2008
- Copyright Details: Avoiding Common Pediatric Errors, Copyright © 2008 Lippincott Williams & Wilkins.
More About Anaphylaxis
More Medical Textbooks Online about Anaphylaxis
Review other book chapters online related to Anaphylaxis:
Medical Books Excerpts
- Anaphylaxis
- "Professional Guide to Diseases (Eighth Edition)" (2005)
- [ read ]
- Shock
- "Field Guide to Bedside Diagnosis" (2007)
- [ read ]
Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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More About This Book:
Title: Avoiding Common Pediatric Errors
Authors: Anthony D Slonim MD, DrPH; Lisa Marcucci MD
Publisher: Lippincott Williams & Wilkins
Copyright: 2008
ISBN: 0-7817-7489-6
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» Next page: Recognize the signs of anaphylaxis (type I hypersensitivity) and know how to treat it aggressively (Avoiding Common Pediatric Errors)
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