3. Concurrently, an intravenous line is established and blood samples are drawn for determination of glucose, intoxicating drugs, and electrolytes and for tests of liver and kidney function. Naloxone, 0.5 mg, should be given intravenously if a narcotic overdose is a possibility. Hypoglycemia that has produced stupor or coma requires the infusion of glucose, usually 25 to 50 mL of a 50 percent solution followed by a 5 percent infusion; this must be supplemented with thiamine. A urine sample is obtained for drug and glucose testing. If the diagnosis is uncertain, both naloxone and the glucose-thiamine combination should be administered.
4. With the development of elevated intracranial pressure from a mass lesion, mannitol, 25 to 50 g in a 20 percent solution, should be given intravenously over 10 to 20 min and hyperventilation instituted if deterioration occurs, as judged by pupillary enlargement or deepening coma. Repeated CT scanning allows the physician to follow the size of the lesion and degree of localized edema and to detect displacements of cerebral tissue. With massive cerebral lesions, it may be appropriate to place a pressure-measuring device in the cranium of selected patients (see Chap. 35 for details of intracranial pressure monitoring and treatment).
5. A lumbar puncture should be performed if meningitis or subarachnoid hemorrhage is suspected on the basis of headache and meningismus (and fever in the case of infectious meningitis), keeping in mind the risks of this procedure and the means of dealing with them. A CT scan may have disclosed a primary subarachnoid hemorrhage, in which case lumbar puncture is not necessary. In the case of meningitis, broad-spectrum antibiotics that penetrate the meninges should be instituted immediately, independent of the timing of the lumbar puncture. The choice of drug is then determined by the principles set forth in Chap. 31. If CSF pressure is greatly elevated when measured from a lumbar puncture that has been performed to diagnose bacterial meningitis, it has been recommended that the stylette should be left in the lumen of the needle, as little CSF should be withdrawn as is necessary for diagnostic purposes, and mannitol or hypertonic saline should be administered to lower the pressure.
6. Convulsions should be controlled by measures outlined in Chap. 15, usually by intravenous diazepines.
7. As indicated earlier, gastric aspiration and lavage with normal saline may be diagnostically and therapeutically useful in some instances of coma due to drug ingestion. Salicylates, opiates, and anticholinergic drugs (tricyclic antidepressants, phenothiazines, scopolamine), all of which induce gastric atony, may be recovered many hours after ingestion. Caustic materials should not be lavaged because of the danger of gastrointestinal perforation. The administration of activated charcoal is indicated in certain drug poisonings. Measures to prevent gastric hemorrhage and excessive gastric acid secretion are usually advisable.
8. The temperature-regulating mechanisms may be disturbed and extreme hypothermia or hyperthermia should be corrected. In severe hyperthermia, evaporative-cooling measures are indicated in addition to antipyretics.
9. The bladder should not be permitted to become distended; if the patient does not void, decompression should be carried out with an indwelling catheter. Needless to say, the patient should not be permitted to lie in a wet or soiled bed.