Causes of Death in Tetanus
Curare is the characteristic feature of a severe case of tetanus. Patients with severe tetanus may also show a group of signs that have often been described but have recently been attributed by workers- in Ox-ford to overactivity of the sympathetic nervous system (Kerr et al.). Many patients sweat profusely and, in some, oxygen uptake and carbon dioxide output are increased. In some patients most severely affected, extreme peripheral vasoconstriction develops with a glove-and-stocking distribution and a sharp line of demarcation be-tween warm skin and cold skin. Hyperpyrexia may also develop. and probably reflects the inability of the vasoconstrictive patient to lose heat.
The most striking features of this syndrome, however, involve the cardiovascular system. Sinus tachycardia occurs and may progress to multi-focal ventricular ectopic beats. The blood pressure is generally elevated and superimposed on these elevation peaks, often associated with spasms or stimuli, in which the systolic pressure may reach 300 mm. Hg, and the diastolic 150 mm. Hg. The syndrome may progress to hypotension that does not respond to pressor agents. Perhaps fortunately, patients with severe tetanus often remember little of their illness and have failed to remember such bizarre incidents as a Union Jack being waved in the ward during the playing of “Rule Britannia.” Electroencephalography shows a sleep pattern, with arousal during stimulation such as tracheal aspiration.
The diagnosis of the established case of tetanus is all too easy, and strychnine poisoning is the only condition that is truly similar to established tetanus. Trismus may occur from dental infections, and the author has seen one case of hysterical tetanus. More recently, overdose with the phenothiazine group of drugs has been confused with tetanus, but the movements in this condition usually include grimacing and jaw movements in which the jaw is opened widely.
CAUSES OF DEATH IN TETANUS
Office of the most remarkable features of tetanus is that when patients recover, even from the most severe forms of the disease, they recover completely. It would therefore seem reasonable to study the causes of death carefully in tetanus so that by avoiding them the natural tendency of the disease toward recovery may be exploited.
- In a survey in Oxford, the causes of death in 18 of 82 patients were bronchopneumonia,
- pulmonary embolus,
- technical, failure,
- coincidental causes,
- and no identifiable cause of death,
Bronchopulmonary complications of tetanus are becoming less common_now that the management of patients receiving IPPV through a tracheotomy tube is better understood, and it is likely that chest complications will become still less common in the future. In general, on the writer's service, a pulmonary embolus is not a common cause of death in patients with other diseases treated by tracheostomy and IPPV.
However, the difference in the incidence of pulmonary embolus between patients with tetanus requiring treatment with curare and IPPV and patients with other diseases similarly treated is so striking that anticoagulants are now used in patients with' tetanus severe enough to merit treatment in this way. The incidence of technical failure underlines the complexity of treating the fully paralyzed patient; the coincidental causes of death apparently had nothing to do with the main disease. No identifiable cause of death could be found in four patients who had all displayed a syndrome suggestive of sympathetic overactivity. A careful study of patients with similar symptoms and signs admitted subsequently has reinforced our belief that in some patients with severe tetanus the sympathetic nervous system is as grossly uninhibited as is the motor nervous system (Prys-Roberts et al.).
There are certain forms of treatment required by all patients with tetanus. Control of Rigidity and Reflex Spasms. Drugs to control rigidity vary with the severity of the case. Barbiturates have been used for many years, and in mild or even moderate cases are useful, but the amount of barbiturate necessary to obtund severe reflex spasms would cause coma. Chlorpromazine has proved antispasmodic properties in tetanus and is a sedative. It also is useful in mild and moderate cases but has been shown by a clinical trial (Adams, 1958) to be no more effective than barbiturates, and like the barbiturates is in-adequate to obtund the spasms in the severest cases.
It may be used in doses of up to 50 mg. intra-muscularly every four to six hours. Mephenesin is a centrally acting muscle relaxant that has been used extensively in the treatment of tetanus with good results, especially in moderate cases, but it must be given frequently and in large doses. The effect of a dose as large as 1 gram can be observed to have diminished significantly in one hour, and this does continue at hourly intervals, which is close to that which will paralyze ventilation.
If it becomes necessary to give paralyzing doses of mephenesin to control rigidity or reflex spasms, it is clearly not the drug of choice. Mephenesin is a local anesthetic and must be given by nasogastric tube. If given intravenously, except in extremely dilute solutions, it will cause hemolysis and hemo-globinuria. Diazepam is currently popular and has been used in mild and moderate cases in doses from 10 mg. every four hours intramuscularly, to 600 mg, intravenously per day. Like the other drugs mentioned above, it will not control the spasms of the severest case, and it is probably unwise to use very large doses. The severity of the case should be admitted and treatment changed to