Critical Care Medicine-Neurologic Disorders>>>>>Spinal Cord Injury
Question 1#

A 27-year-old male was brought to the ICU following a motorcycle crash resulting in bilateral open femur fractures, grade IV splenic laceration, and traumatic spinal cord transection at T3.

Which of the following is NOT an expected disease-related physiological change?

a. Decreased systemic vascular resistance
b. Hypothermia
c. Increased vital capacity (VC)
d. Bradycardia

Correct Answer is C

Comment:

Correct Answer: C

SCI can lead to neurogenic shock, which consists of bradycardia and severe arterial hypotension. It is due to autonomic nervous system malfunction and is caused by the lack of sympathetic activity, through loss of supraspinal control and unopposed parasympathetic tone via intact vagus nerve. Lesions between T1-T4 interrupt the cardiac accelerator fibers resulting in significant bradycardia along with hypotension, decreased vascular tone, and venous pooling. 

Lesions at or above T7 cause impaired functioning of intercostal muscles, which causes reduction in VC and expiratory reserve volume, leading to hypoventilation and hypoxia. Disruption of the sympathetic nervous system due to SCI also results in impaired thermoregulatory function secondary to interruption of signal transmission to the hypothalamic temperature regulating center. This leads to hypothermia, which is characteristic of neurogenic shock.

References:

  1. Krassioukov AV, Claydon VE. The clinical problems in cardiovascular control following spinal cord injury: an overview. Prog Brain Res. 2007;152:223-229.
  2. Grigorean VT, Sandu AM, Popescu M, et al. Cardiac dysfunctions following spinal cord injury. J Med Life. 2009;2(2):133-145.
  3. Miller RD, Miller ED, Reves JG, et al. Anesthesia. Vols. 297–298. 7th ed. New York, NY: Churchill Livingstone; 2009:2299.