Hypothermia complications

Death from overdose of barbiturates may occur and is more likely when more than 10 times the hypnotic dose is ingested. The barbiturates with high lipid solubility and short half-lives are the most toxic. Thus the lethal dose of phenobarbital is 6—10 g, whereas that of secobarbital, pentobarbital, or amo-barbital is 2-3 g. Symptoms of barbiturate poisoning include CNS depression, coma, depressed reflex activity, a positive Babinski reflex, contracted pupils (with hypoxia there may be paralytic dilation), altered respiration, hypothermia, depressed cardiac function, hypotension, shock, pulmonary complications, and renal failure. 

Georgiadis et al. Stroke 2002 33(6) 1584-1588 Nonblinded prospective hemicraniectomy for nondominant and cooling for dominant hemisphere 19 of 36 tx with hypothermia Hypothermia to 33°C with cooling blankets or endovascular technique on clinical course in pts with >2/3 MCA infarct 12% vs. 47% mortality for surgery vs. hypothermia. Hypothermia with increased complications of hypotension and electrolyte abnormalities. Both tx with longer ICU course... 

Decompressive hemicraniectomy was indirectly compared with moderate hypothermia (33°C) in a series of 36 patients from Georgiadis et al. They found a lower mortality rate for the patients who underwent hemicraniectomy (47% vs. 12%), as well as a lower complication rate. However, this was not a randomized study, and there was no comparison arm of patients who did not undergo either experimental therapy. 

It produces severe toxic manifestations. Either suicidal or accidental intake of toxic doses of barbiturates is characterized by depressed respiration, circulatory shock, pupils are initially constricted then dilated due to asphyxia, hypothermia, renal failure and pulmonary complications such as acute pulmonary edema. 

Anorectic patients often suffer from complications such as hypotension, hypothermia, and abnormal ECGs, all of which are consistent with starvation. In women, amenorrhea is common with this syndrome. Like patients with depression, they also have high cerebrospinal fluid concentrations of corticotropin-releasing hormone. 

The need to cool patients quickly while at the same time reducing complication rates has led to the development of simpler methods of rapidly inducing and maintaining hypothermia. More modest hypothermia can now be achieved in awake patients with acute stroke by surface cooling with the forced air method in combination with pethidine to treat shivering (75), and several intravenous vascular cooling techniques look encouraging (48-50). 

Matsushita Y., BramlettH. M., Alonso O., and Dietrich W. D. (2001) Posttraumatic hypothermia is neuroprotective in amodel of traumatic brain injury complicated by a secondary hypoxic insult. Crit. Care Med. 29, 2060-2066. 

It is clear from this discussion that although there is significant potential for the use of hypothermia in combination with additional neuroprotective agents, it is premature to consider this a viable option in the near future. Moreover, there are no adequate data on the safety of such combination therapy. In fact, there is some evidence suggesting that hypothermia could result in such adverse effects as reduced thrombolytic efficacy and increased susceptibility to infectious complications. 

Mild hypothermia has been easily incorporated into the overall care of patients in various clinical settings. However, there is a potential for multisystem complications when it is used. Although mild hypothermia (32-34°C) is not usually responsible for cardiac dysrhythmias, it has been associated with electrical conduction disturbances secondary to its potentiation of other drugs, particularly neuromuscular blocking agents (4,45,46). There is a tendency to develop atrial fibrillation at temperatures below 32°C (47). During periods of mild hypothermia,... 

Hypothermia has been shown to cause coagulopathies (106). This hypothermic complication, however, is seen primarily when patients are cooled to temperatures less than 30°C (106). In a phase II clinical study, Clifton et al. (17) showed an increase in the PT (p < 0.001) and... 

Acute extrapyramidal reactions occur more often after ingestion of high-potency drugs, such as haloperidol and fluphenazine these respond to parenteral benzatropine, but anticholinergic drugs should be used judiciously, so as not to worsen peripheral or central autonomic toxicity. Other serious, but less frequent, complications include paralytic ileus and hypothermia. Acute renal insufficiency has been very rarely reported, but is apparently reversible and can occur secondary to severe hypotension or other causes after acute ingestion (615). 

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