Intravenous cooling

Rapid cooling by tepid sponging, fan-assisted evaporation and cooled intravenous fluids is the first step. Paralysis and ventilation may be necessary, especially if the patient is non-compliant as a result of cerebral dysfunction, or is shivering, indicating that thermoregulation has broken down. 

The cardiac arrhythmias are life-threatening, so the patient must be closely monitored, with facilities available for possible resuscitation. Drugs such as quinidine and procainamide are contraindicated, but lidocaine, propranolol, or phenytoin has been used safely and effectively. The arterial blood gas levels, pH, and electrolyte concentrations should be monitored so that metabolic acidosis or hypokalemia can be identified that would further aggravate the arrhythmias. Electrical pacing may be required if the antiarrhythmic drugs fail. Hyperpyrexia is treated by cooling. Seizures may be managed by intravenous doses of diazepam. 

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). 

Patients with a low surface to volume ratio may take considerably longer to cool by surface techniques. For these patients additional cooling can be provided by the use of chilled intravenous solutions, bladder irrigation, and gastric lavage. 

The main use of PVC is for intravenous bags. However, PVC has been used in the controlled release of volatile insecticides, herbicides, pheromones, and perfumes by diffusion through a PVC membrane of multilaminated stripes. A monolithic matrix device of PVC can be prepared by mixing PVC particles with a suitable plasticizer and an active agent, followed by heating of the mixture in a mold. A solid PVC matrix is obtained from the subsequent cooling. 

Early study of bronchoconstricitive mechanisms of sulfur dioxide with ventilated, tracheostomized cats indicated that pulmonary resistance increased during the first breath but reversed rapidly (Nadel et al. 1965). Intravenous injection of atropine (a parasympathetic receptor blocker) or cooling of the cervical vagosympathetic nerves abolishes bronchoconstriction rewarming the nerve reestablishes the response. The rapidity of the response and its reversal emphasize the parasympathetically mediated tonal change in smooth muscle. Studies with human subjects have confirmed the predominance of parasympathetic mediation, but histamine from inflammatory cells could play a secondary role in the bronchoconstrictive responses of people with asthma (Sheppard et al. 1981). 

There is no specific antidote for strychnine but recovery from strychnine exposure is possible with early hospital treatment. Treatment consists of removing the drug from the body (decontamination) and getting supportive medical care in a hospital setting. Supportive care includes intravenous fluids, medications for convulsions and spasms, and cooling measures for high temperature. 

A 28-year-old man, who developed malignant hyperthermia after anesthesia induced with isoflurane and maintained with sevoflurane, died 4 days later, despite cooling and intravenous dantrolene (49). 

Malignant hyperthermia is a rapidly progressing life-threatening condition. On suspected diagnosis, all anesthetic drugs are stopped and 100% oxygen is given. Intravenous dantrolene, an inhibitor of sarcoplasmic Ca release, should be administered and the patient should be cooled as rapidly as possible with ice. 

All basic and advanced life-support measures should be implemented. Gastric decontamination should be performed. Butyrophenones are readily absorbed by activated charcoal. Aggressive supportive care should be instituted. Dystonic reactions respond well to intravenous benztropine or diphenhydramine. Oral therapy with diphenhydramine or benztropine should be continued for 2 days to prevent recurrence of the dystonic reaction. For patients suffering from neuroleptic malignant syndrome, a potentially fatal condition associated with the administration of antipsychotic drugs, dantrolene sodium, and bromocriptine have been used in conjunction with cooling and other supportive measures. Arrhythmias should be treated with lidocaine or phenytoin. Diazepam is the drug of choice for seizures phenytoin is used to prevent recurrence. Hemodialysis and hemoperfu-sion have not been shown to be effective. 

An emetic (ipecac) should be administered to induce vomiting and prevent further absorption. Gastric lavage can be performed to remove metaldehyde from the gastrointestinal tract. If hyperthermia is noted, a cool-water bath can be given to lower body temperature. Sedatives, e.g., diazepam, can be given to control anxiety, seizures, and tremors. Intravenous fluids should be given to correct dehydration and acidosis. 

Intensive supportive care is rarely required. Measures that may be required based on the clinical presentation include endotracheal intubation and assisted ventilation if coma is present, intravenous fluid resuscitation if hypotension is present, pharmacological control of seizures, cooling if hyperthermia is present. 

Treatment entails intravenous administration of dantrolene (dantrium), which blocks Ca release and its sequelae in skeletal muscle. Rapid cooling, inhalation of 100% oxygen, and control of acidosis should be considered adjunct therapy in malignant hyperthermia. 

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