23.1 Shock Overview

Shock is a state of inadequate cellular perfusion.
Hemodynamic monitoring is the physical study of flowing blood and all solid structures where blood flows. It is useful in understanding the diagnosis and treatment of shock.
During the initial stage of shock, clinical manifestations are not overtly apparent; however, changes occur at the cellular level.
In the compensatory stage of shock, cell hypoperfusion causes a drop in blood pressure, tachycardia, cool skin, increased respiratory rate, and a decrease in urine output.
In the progressive stage of shock, compensatory mechanisms fail and altered capillary permeability causes fluid to leak from the vascular system into the interstitial tissue.
Vital signs in the progressive stage of shock include low blood pressure, increased heart rate, low urine output, increased respiratory rate, and cool skin with discoloration of peripheral extremities with weak distal pulses.
In the refractory stage of shock, continued capillary permeability and cell hypoxia lead to cell death. Recovery is not likely from this stage of shock.
Multiorgan failure (MOF), also referred to as multiorgan dysfunction syndrome (MODS), is a critical illness characterized by inflammation from a severe infection or simultaneous injuries to two or more organ systems.
The direction of blood is forced to divert to the vital organs of the body, such as the heart, lungs, and brain.

23.2 Hypovolemic Shock

An effective heart pump, sufficient blood volume, and appropriate sympathetic tone to blood vessels are needed to maintain adequate cell perfusion.
Hypovolemic shock results when there is insufficient volume in blood vessels to maintain cell perfusion.
Treatment of hypovolemic shock aims to identify and correct the source of volume loss.
Absolute hypovolemia can result from overt bleeding, excessive vomiting or diarrhea, fistula drainage, diabetes insipidus, hyperglycemia, or diuresis.
Relative hypovolemia results from fluid movement from cells and blood vessels into the interstitial space. Causes of this shift include bowel obstruction, burn injury, ascites, long bone fracture, hemothorax, severe pancreatitis, and sepsis.
During hypovolemic shock, the body attempts to compensate for decreased vascular volume by increasing the sympathetic tone to blood vessels, increasing the sympathetic tone to the heart, increasing rate and contractility, and diverting blood to vital organs.
Anaerobic metabolism, the accumulation of waste products, results from the hypoperfusion of cells.
Manifestations of hypovolemic shock include increased heart rate, decreased blood pressure, increased respiratory rate, decreased urine output, and cool clammy skin.
Treatment for hypovolemic shock focuses on identifying the source of volume loss, stopping the source of volume loss, and restoring appropriate volume. Some patients require the administration of medications to maintain hemodynamic stability.

Sepsis is a serious condition resulting from the body’s overreaction to the presence of bacterial, fungal, or viral infection.
Sepsis leads to an immediate inflammatory process throughout the body; severe sepsis results in organ malfunction, and septic shock is a cause of significant morbidity and mortality.
MOF/MODS is a clinical syndrome characterized by the development of progressive and potentially reversible physiologic dysfunction in two or more organs or organ systems that is induced by a variety of acute insults, including sepsis.
Early recognition and treatment of sepsis result in improved patient outcomes.
Classic manifestations of septic shock include hypotension, tachycardia, tachypnea, low urine output, and mottled skin.
The release of endotoxins from microorganisms causes vasodilation, maldistribution of blood flow, and myocardial dysfunction.
Patients require care provided in an intensive care environment.
If profound hypotension is unresponsive to fluid therapy, vasopressors are needed.

Neurogenic shock is a life-threatening medical condition caused by the sudden loss of sympathetic nerve stimulation, which is necessary to maintain normal muscle tone in the blood vessels. As a result, there is insufficient blood flow throughout the body, causing low blood pressure.
Neurogenic shock is caused by the loss of vasomotor tone in the blood vessels, not by insufficient volume.
Dilation of arteries and veins results in the pooling of blood and inadequate perfusion of cells and body tissues.
The most common cause of neurogenic shock is spinal cord injury. Other causes include complications from spinal anesthesia and head trauma.
Hallmark findings in neurogenic shock include hypotension, bradycardia, and initially warm, dry skin above the level of the injury.
Fluid resuscitation is the first-line treatment to restore blood pressure; however, vasopressors are often needed to restore cell and tissue perfusion.
Emergent nursing care for patients with neurogenic shock includes the ABCs, along with protecting the cervical spine and preventing secondary spinal cord injury.
Continual assessments and interventions should be incorporated into care to prevent long-term complications.