What is Neurogenic Shock?
Neurogenic shock is a distributive shock. It follows a sudden loss of sympathetic signals that normally hold muscle tone in the blood vessel walls. When that balance between sympathetic and parasympathetic stimulation breaks, the vessels dilate, blood flow falls, and the patient is in a life-threatening state.
Pathophysiology
Sympathetic stimulation constricts vascular smooth muscle; parasympathetic stimulation relaxes and dilates it. In neurogenic shock, unopposed parasympathetic stimulation causes prolonged vasodilation, creating a relative hypovolemic state. Blood volume is actually adequate, but the dilated vasculature displaces it, dropping the pressure. The same parasympathetic override sharply lowers systemic vascular resistance and produces bradycardia. The inadequate pressure leaves tissues and cells underperfused, the common endpoint of every shock state.
Statistics and Incidences
Neurogenic shock most often complicates traumatic spinal cord injury, and the risk rises with higher and more complete injuries. It is typical of cervical and high-thoracic cord injury and uncommon below roughly the T6 level, since lesions above that point disrupt the sympathetic outflow that maintains vascular tone.
Causes
Spinal cord injury (SCI) is the recognized cause of the hypotension and bradycardia of neurogenic shock. Spinal anesthesia, injection of an anesthetic into the space around the spinal cord, or severance of the cord drops blood pressure by dilating the vessels in the lower body and cutting venous return to the heart. The depressant action of medications and a lack of glucose can also trigger it.
Clinical Manifestations
The signs are signs of parasympathetic stimulation. The skin is dry and warm rather than cool and moist, because the patient cannot vasoconstrict. Hypotension follows the sudden, massive dilation. The patient is bradycardic, not tachycardic. If the injury is below the 5th cervical vertebra, expect diaphragmatic breathing from loss of intercostal muscle control. If the injury is above the 3rd cervical vertebra, the patient goes into respiratory arrest immediately from loss of nervous control of the diaphragm.
Assessment and Diagnostic Findings
A CT scan gives a better look at abnormalities seen on x-ray. X-rays are ordered for people suspected of spinal cord injury after trauma. MRI uses a strong magnetic field and radio waves to produce detailed images.
Medical Management
Treatment restores sympathetic tone, either by stabilizing a spinal cord injury or, with spinal anesthesia, by positioning the patient appropriately. A suspected spinal cord injury may need traction to stabilize and realign the spine. IV fluids are given first to stabilize blood pressure. After acute spinal cord injury, maintaining mean arterial pressure around 85 to 90 mmHg for up to 7 days supports spinal cord perfusion and may limit secondary injury (AANS/CNS).
Pharmacologic Therapy
A vasopressor with both alpha and beta activity, such as norepinephrine, is preferred to support blood pressure and heart rate together; dopamine is an alternative. Atropine is given intravenously for severe or symptomatic bradycardia (FDA atropine label). High-dose IV steroids such as methylprednisolone are no longer routinely recommended: updated AANS/CNS guidelines advise against methylprednisolone for acute spinal cord injury, citing evidence of more harm than benefit. Heparin or low molecular-weight heparin, as prescribed, helps prevent thrombus formation.
Nursing Management
Nursing Assessment
Run the basic airway, breathing, circulation approach to the trauma patient while protecting the spine from any extra movement. Identify neurologic deficits and the general level at which abnormalities began.
Nursing Diagnosis
- Risk for impaired breathing pattern related to impaired innervation of the diaphragm (lesions at or above C-5).
- Risk for trauma related to temporary weakness or instability of the spinal column.
- Impaired physical mobility related to neuromuscular impairment.
- Disturbed sensory perception related to destruction of sensory tracts with altered sensory reception, transmission, and integration.
- Acute pain related to pooling of blood secondary to thrombus formation.
Nursing Care Planning and Goals
The patient should maintain adequate ventilation with no respiratory distress and ABGs within acceptable limits, and demonstrate behaviors that support respiratory effort. The spine should stay properly aligned without further cord damage, and the patient should maintain a position of function with no contractures or foot drop. Goals also include increasing strength in unaffected or compensatory body parts, demonstrating techniques that enable a return to activity, recognizing sensory impairments, identifying behaviors that compensate for deficits, and verbalizing awareness of sensory needs and the potential for deprivation or overload.
Nursing Interventions
Interventions support cardiovascular and neurologic function until the usually transient episode resolves. Elevate the head of the bed: after spinal or epidural anesthesia, this helps keep the agent from spreading up the cord. Apply anti-embolism stockings and elevate the foot of the bed to minimize blood pooling in the legs and prevent thrombus formation. Use passive range of motion on immobile extremities to promote circulation. Maintain a patent airway by keeping the head neutral, elevating the head of the bed slightly if tolerated, and using airway adjuncts as indicated. Give oxygen by the appropriate method (nasal prongs, mask, intubation, ventilator). Plan activities around uninterrupted rest periods and encourage involvement within the patient's tolerance. Measure and monitor BP before and after activity in the acute phase or until stable. Help the patient recognize and compensate for altered sensation to reduce anxiety.
Evaluation
Confirm the goals were met: ventilation stayed adequate, the patient supported respiratory effort, the spine held proper alignment without further cord damage, a position of function was maintained, strength increased in unaffected or compensatory parts, the patient demonstrated techniques for resuming activity, recognized sensory impairments, identified compensating behaviors, and verbalized awareness of sensory needs and the risk of deprivation or overload.
Documentation Guidelines
Document the relevant history of the problem; respiratory pattern, breath sounds, and accessory muscle use; lab values; past and recent injuries and awareness of safety needs; use of safety equipment or procedures; environmental and safety concerns; level of function and ability to participate in desired activities; the patient's description of pain, the pain inventory, expectations of pain management, and acceptable pain level; prior medication use; the plan of care, specific interventions, and who was involved in planning; the teaching plan; response to interventions, teaching, actions, and the treatment regimen; attainment or progress toward desired outcomes; and any modifications to the plan of care.
Frequently Asked Questions
What makes neurogenic shock different from other types of shock?
The tell is hypotension with bradycardia and warm, dry skin. Lost sympathetic tone leaves the patient unable to vasoconstrict, so unlike hypovolemic or septic shock the heart rate is slow and the skin is not cool and clammy.
What causes neurogenic shock?
Spinal cord injury is the recognized cause, typically at the cervical or high-thoracic level. Spinal anesthesia, an anesthetic injected around the cord, or severance of the cord can also trigger it by dropping vascular tone and venous return.
How is the low blood pressure managed?
IV fluids come first, then a vasopressor if pressure stays low. Current guidance favors an agent with both alpha and beta activity, such as norepinephrine, and a mean arterial pressure goal around 85 to 90 mmHg for up to 7 days after spinal cord injury (AANS/CNS).
How is the bradycardia treated?
IV atropine is given for severe or symptomatic bradycardia (FDA atropine label). Glycopyrrolate is an alternative, and a vasopressor with beta activity also helps raise the rate.
Are high-dose steroids recommended?
No. Updated AANS/CNS guidelines recommend against methylprednisolone for acute spinal cord injury, because the evidence shows more harm, including infection, than benefit.
Why is airway protection an early priority?
An injury above the 3rd cervical vertebra can cause immediate respiratory arrest from loss of diaphragm control, and an injury below the 5th cervical vertebra produces diaphragmatic breathing. Protect the airway and the spine while supporting blood pressure.