Cardiovascular Critical Care II

Anaesthesiol Scand 1998;42:1222-6; J Cardiothorac Vasc Anesth 1996;10:336-41), which

requires central/core temperatures by esophageal, bladder (avoid in anuric patients), or

pulmonary artery temperature monitoring. Ideally, the monitoring modality chosen will

be used for other indications as well.

The major complications of temperature control are related to the physiologic and adaptive

responses to the temperature-changing process of temperature control (Table 4). The adverse

events of sepsis, myoclonus, seizures, and hypoglycemia within 72 hours of temperature control

Musculoskeletal

N Engl J Med 2013;369:2197-206;

Anesthesiology 2009;111:110-5; Br

J Anaesth 2005;94:756-62; N Engl

J Med 2002;346:549-56; N Engl

1960;198:481-6)

Shivering:

Body’s natural response to hypothermia, preceded by arteriovenous

vasoconstriction; most common complication of hypothermia; can increase

metabolic heat production by 600%, thereby slowing the induction of

hypothermia. Typically slows or stops at core temperatures < 33.5°C

1.  Agents that decrease the shivering threshold (i.e., decreases the

temperature at which shivering will occur):

a)  Scheduled acetaminophen 650 mg q4–6 hr or buspirone 30 mg

q12 hr reduces the shivering threshold by 0.2ºC–0.4ºC

b)  Magnesium sulfate reduces the shivering threshold by ~0.3°C

c)  Meperidine decreases the shivering threshold by up to 2°C but

should be avoided because of decreased effective glomerular

filtration rate (GFR) during hypothermia and increased risk of

seizures when meperidine is used in patients with decreased GFR

d)  Dexmedetomidine and clonidine decrease the shivering threshold

by ~0.8°C, but extreme caution should be used because of the

hypotensive and bradycardic effects of both agents

e)  Propofol decreases the shivering threshold by ~0.6°C and has a

linear relationship between serum concentrations and reduction in

body temperature; caution should be used, given the hypotensive

and bradycardic effects

2.  Options to stop shivering include:

a)  Continuous or as-needed paralytics can be used for prevention

and treatment of shivering (see the chapter on management of

paralytics for appropriate selection and dosing of agent[s])

—Hypothermia decreases clearance and prolongs the duration of

neuromuscular blockade (see Table 5 for examples)

—Train of four is not a reliable method of monitoring

during hypothermia; clinical monitoring or continuous EEG

(electroencephalography) may be warranted

b)  Surface warming if using internal cooling devices

c)  Chilled fluids to promote faster core temperature reduction