A. Crampton Smith

INVOLVEMENT OF THE SYMPATHETIC NERVOUS SYSTEM IN TETANUS: Studies on 82 Cases

Abstract Retrospective studies are described on a series of 82 patients with tetanus, 44 of whom were treated by tracheostomy, curarisation, and intermittent positive-pressure ventilation. Patients with severe tetanus may develop a characteristic syndrome whose features include sustained but labile hypertension and tachycardia, irregularities of cardiac rhythm, peripheral vascular constriction, profuse sweating, pyrexia, increased carbon-dioxide output, increased urinary catecholamine excretion, and, in some cases, the late development of hypotension. It is argued that this syndrome may be due to continuous but fluctuating overactivity of the sympathetic nervous system.

CONTROLLED TRIAL OF REPEATED HALOTHANE ANÆSTHETICS IN PATIENTS WITH CARCINOMA OF THE UTERINE CERVIX TREATED WITH RADIUM

39 patients with carcinoma of the uterine cervix who were treated with radium and required repeated general anaesthetics were randomised to halothane and control groups. Their serum-alanine-aminotransferase (S.G.P.T.) levels were measured before each general anaesthetic, and those patients whose S.G.P.T. levels rose above 100 I.U. per litre were freed from the restriction determined by the initial allocation and treated as indicated clinically. None of the 21 patients in the control group had S.G.P.T. levels rising above 100 I.U. per litre. 4 out of 18 patients in the halothane group developed S.G.P.T. levels above 100 i.u. per litre before their third radium treatment. None of these had any symptoms or alteration in other liver-function tests, but liver biopsies in 2 of these patients showed changes characteristic of Hepatitis. Arbitrary selection of 18 out of the 39 patients would only give rise to the degree of abnormality observed in the halothane-treated group with a probability of about 0-02. In the patients studied who required repeated general anaesthetics at short time intervals, the monitoring of S.G.P.T. levels before each operation was useful screen for liver damage and may have reduced postoperative hepatic necrosis by preventing further anaesthetics with halothane when the liver was already damaged.

TREATMENT OF SYMPATHETIC OVERACTIVITY IN TETANUS

Abstract Treatment directed towards suppressing sympathetic overactivity was assessed in four patients who had profound circulatory disturbances during severe tetanus. Chlorpromazine did not provide satisfactory control of these disturbances, and prolonged general anaesthesia, although otherwise successful, was limited by the potential toxicity of the agents used. A combination of propranolol and bethanidine was used in three patients to block adrenergic effector mechanisms, and proved satisfactory in controlling the hypertension, tachycardia, and cardiac dysrhythmias.

METABOLIC ACIDOSIS OF THE CEREBROSPINAL FLUID ASSOCIATED WITH SUBARACHNOID HÆMORRHAGE

Abstract In the presence of subarachnoid haemorrhage, the hydrogen-ion concentration of cerebrospinal fluid (C.S.F.) is increased and the bicarbonate concentration is reduced. The fall in pH is associated with a rise in the lactate concentration of the C.S.F. which is too large to be attributed entirely to the effects of hyperventilation. The lactate is probably derived from glycolysis by the enzyme systems of the shed blood-cells. The fall in C.S.F. pH is associated with a fall in C.S.F. bicarbonate concentration, a fall in C.S.F. and P a CO 2 , and with an arterial alkalaemia. This pattern of C.S.F. and arterial acid-base disturbance differs from conventional forms of acid-base disorder, and it may be termed a primary metabolic acidosis of the cerebrospinal fluid.

TEMPERATURE REGULATION IN SURVIVORS OF ACCIDENTAL HYPOTHERMIA OF THE ELDERLY

Abstract Eight survvivors from accidental hypo- thermia of the elderly, and three elderly controls who were not known to have had hypothermia were examined. Central and superficial body tempera- tures, shivering, hand blood-flow or finger heat elimina- tion, blood-pressure and, in three survivors and the controls, oxygen consumption were recorded when the subjects were comfortably warm and when their skin was cooled with a fan. The controls showed responses similar to those of younger healthy individuals. The survivors resting central temperature was low. On exposure to cold it fell progressively and abnormally. Evidence is presented that this is due ti impairment of the increase in heat production and decrease in heat loss normally evoked by exposure to cold. This abnormality of body temperature regulation is probably a major aetiological factor in accidental hypothermia of the elderly. It was present as much as 3 years after recovery from accidental hypo- thermia of the elderly, and survivors from accidental hypothermia of the elderly therefore must be regarded at risk from another episode of hypothermia when exposed to only moderate cold.

Cardiovascular disturbances in severe tetanus due to overactivity of the sympathetic nervous system

I n a previous communication1 based on a retrospective study of 82 cases of tetanus, it was postulated that overactivity of the sympathetic nervous system could account for many features of the disease which cannot be explained on the basis of hyperexcitability of motor neurones. It seems likely that some of these features, in particular the severe cardiovascular disturbances, contribute to the still considerable mortality and morbidity of the disease. This paper describes physiological observations on six patients with severe tetanus treated with curare and intermittent positive pressure ventilation (IPPV). The findings support our previous suggestion that overactivity of the sympathetic nervous system is an integral part of severe tetanus.

CLASSIFICATION OF CHEST INJURIES AS AN AID TO TREATMENT.

Borrie, J., and Lichter, I. (1964). N.Z. med. 7., 63, 31. Burchell, H. B. (1961). Circulation, 24, 161. Jessen, C., and Rosen, J. (1963). Acta chir. scand., 125, 567. Noordijk, J. A., Oey, F. T. I., and Tebra, W. (1961). Lancet, 1, 975. Swedberg, J., Johansson, B. W., Karnell, J., and Malm, A. (1963). Acta chir. scand., 125, 547. Weinberg, D. I., Artley, J. L., Whalen, R. E., and McIntosh, H. D. (1962). Circulat. Res., 11, 1004.

EFFECT OF MECHANICAL VENTILATION ON THE CIRCULATION.

In this paper, I shall try to summarize some current aspects of knowledge of the effects of mechanical artificial respiration on the circulation; to suggest how undesirable effects may be modified; and finally briefly to describe some recent observations we have made in Oxford. I shall speak only of mechanical intermittent positive pressure respiration (IPPR) or positive-negative pressure respiration. given through a cuffed tracheotomy tube. IPPR is a reversal of normal physiological pressure relationships in the thorax. The normal subatmospheric intrathoracic pressure during inspiration, which creates a favorable pressure gradient between peripheral veins and right heart, is replaced by a positive pressure which impedes venous return. IPPR has been described as a series of minor Valsalva maneuvers, and both IPPR and Valsalva maneuver can, in certain circumstances, affect the circulation adversely. Many excellent papers have been written on this subject and I would remind you of a few of my own favorites. In 1938 Humphreys and others (1938) showed that a rise in tracheal pressure was accompanied by a rise in jugular venous pressure, and that in dogs whose respiration had been paralyzed with curare intermittent inflation of the lungs was, in these experiments, accompanied by a fall in cardiac output. About 1947-1948 an important group of papers came from Cournand’s laboratory. My favorite is that by Cournand (1948) in the American Journal of Physiology. This paper describes the effects of various mask positive pressure waveforms on the cardiac output in men breathing under positive pressure from tightly fitting face masks. It was concluded that the higher the mean mask pressure, the lower the cardiac output. No fall in cardiac output was found with a mask positive pressure waveform which was considered desirable. It had the following characteristics: (1) There was a gradual increase in positive pressure during inspiration. (2) There was a rapid drop after cycling to a pressure close to atmospheric. (3) Expiratory time was equal to or exceeded inspiration. That is, the mean mask pressure was kept low and sufficient time was given at atmospheric pressure during expiration for a raised venous pressure and Starling’s law to compensate for the inspiratory period of obstruction to venous return. When it had been established that cardiac output could fall during IPPR, and that this fall, presumably due to a reduction in venous return, was proportional to the mean mask pressure, the logical next step was to reduce this pressure as far as possible. This can be done by making the duration of inspiration infinitely short, and I wish to discuss this later. It can also be done by introducing a subatmospheric mask or tracheal pressure during expiration and hence substituting a favorable pressure gradient from veins to heart in expiration for that normally occurring in inspiration. J. V. Maloney attributes the earliest interest in this expiratory subatmospheric pressure to S. A. Thompson ( 1948). He cannot, however, absolve himself from a great deal of responsibility for this considerable advance. My favorite paper in this connection is that by J . V. Maloney and S. A. Handford (1954) in which it is concluded that “experimental animals with competent circulatory and respiratory systems tolerate either positive/ negative or I.P. type respirators without major alterations in blood pressure or cardiac output.