Which of the following statements about shivering is correct?
A. Shivering is a response controlled by the brainstem.
B. Shivering can occur in the absence of hypothermia.
C. Shivering is effectively treated with small doses of naloxone.
D. Shivering is an uncomfortable, though harmless, effect of anesthesia.
Correct Answer: B. Shivering can occur in the absence of hypothermia.
Shivering can also appear after surgery. This is known as postanesthetic shivering. Postoperative shivering is a common complication of anesthesia. Shivering is believed to increase oxygen consumption, increase the risk of hypoxemia, induce lactic acidosis, and catecholamine release. Therefore, it might increase postoperative complications, especially in high-risk patients. Moreover, shivering is one of the leading causes of discomfort for postsurgical patients.
Option A: Shivering is usually triggered by hypothermia. However, it occurs even in normothermic patients during the perioperative period. The etiology of shivering is not understood sufficiently. Shivering is elicited when the preoptic region of the hypothalamus is cooled. Efferent signals mediating shivering descend in the medial forebrain bundle. Spinal alpha motor neurons and their axons are the final common path for both coordinated movement and shivering
Option C: Many drugs have been shown to be effective on the prevention and treatment of PS, such as opioids, ?2-agonists, anticholinergics, central nervous system stimulants, corticosteroids. Highly effective anti shivering medication classes were centrally acting analgesics (tramadol), opioid receptor agonists (meperidine, fentanyl), cholinesterase inhibitors (physostigmine), and N-methyl-D-aspartate receptor antagonists (ketamine, magnesium sulfate).
Option D: Patients report that shivering is remarkably uncomfortable, and some even find the accompanying cold sensation worse than surgical pain. In addition, shivering might stretch surgical incisions and, as a consequence, it may intensify post-surgical pain. Besides the obvious discomfort in the recovery period, PS increases oxygen consumption, induce lactic acidosis, carbon dioxide production, and catecholamine release, resulting in increased cardiac output, heart rate, and arterial pressure.