O. Dottori

Fatal Iron Intoxication in Late Pregnancy

A case of intoxication with 5 g of elemental iron (25 g of ferrous sulfate) in a 30-year old woman at 36 weeks gestation is reported. Deferoxamine treatment was given with a delay of 26 hours after ingestion. A healthy infant was delivered by cesarean section 31 hours following ingestion. Subsequently, the patient developed hepatic necrosis, coma and hemostatic dysfunction and expired in cardiac failure after two weeks. The fatal outcome supports the view that the potential lethal dose of iron is lower for adults than for children. This case also demonstrates that major hepatic dysfunction can be a prominent feature of adult cases of iron intoxication. It is not unequivocal that early institution of deferoxamine treatment would have had a significant influence on the outcome. However, taking into account the well-documented efficacy of the drug in children and that no major adverse fetal effects have been associated with deferoxamine treatment in pregnancy, we suggest such antidote therapy to be considered for prompt institution in similar cases.

EFFECT OF INTERCOSTAL BLOCK ON LUNG FUNCTION AFTER THORACOTOMY

Postoperative pain is an important cause of reduced lung function after thoracotomy. The recognised favourable effect of intercostal block is limited by the relatively short duration of the common local anaesthetics. Attempts with long-acting local anaesthetics, e.g. DurocainB or EfocainB, have been disappointing; the former drug proved to destroy the nerve completely, while the latter caused neurological complications (Aronsen & Lundskog ( 1955)23 3, Angerer et al. (1953)l, Shapiro & Norman (1953)y. The introduction of a new long-acting local anaesthetic, LAC 43*, without serious side effects, raised our interest in this method of relief of pain. The aim of the present investigation was to study:1. The lung function during the early postoperative period by means of dynamic spirometric methods and blood-gas analysis. 2. The effect on lung function of intercostal block (LAC 43 as well as shortacting local anaesthetics) compared with the ordinary postoperative care. Material.-Fifty-one thoracotomy patients were studied (table 1). Initially, a pilot study was attempted with 15 patients selected at random, using a double-blind technique, but this was found impracticable because of the obvious difference in clinical effect. The person who had given the injection could easily guess the drug used. On the other hand, the lung-function tests were performed by other persons who had no opportunity of knowing the analgetic effect. Group IV comprises only six patients. Since these injections inflicted such discomfort on the patients the procedure was discontinued. The type of operations is shown in table 2. In the selection of cases, patients with obstructive lung disease were avoided.

MUSCLE PAINS AFTER SUXAMETHONIUM

Muscle pains after intermittent administration of suxamethonium are a common complication in modern anaesthetia. They can be prevented to a certain extent through postoperative immobilization of the patient. However, it is important to mobilize the patients as early as possible, particularly in the elderly age groups. In these cases, it is therefore of the greatest importance to prevent postoperative muscle pains, which can be of considerable intensity. We have tried a method in which increasing doses of tubocurarine were given before administration of suxamethonium. At a dosage of 3 mg tubocurarine the patients were kept free from pain, but more suxamethonium was necessary for relaxation. We have found no untoward effects of this method.

The Haemodynamic Effects of Nitrous Oxide Anaesthesia on Systemic and Pulmonary Circulation in Dogs

The haemodvnamic effects of nitrous oxide in normoxia (20% oxygen) and in hyperoxia (50% oxygen) were investigated in 13 dogs. Nitrous oxide in hyperoxia caused a significant rise in total peripheral resistance and a significant decrease in cardiac output, heart rate, myocardial contractility (dP/dt max) and cardiac worl?. On the other hand, nitrous oxide in normoxia seemed to reverse these findings and did not exert any negative inotropic effects on the myocardium. The results indicate that the earlier reported sympathetic activation of the circulation may be related to hyperoxia and not to nitrous oxide as such.

The haemodynamic effects of nitrous oxide anaesthesia on myocardial blood flow in dogs.

The effects of ventilation with nitrous oxide in oxygen on myocardial blood flow and oxygen metabolism were investigated in 31 mongrel dogs. The results of this study showed that, compared with controls, hyperoxic nitrous oxide mixtures did not cause any great changes in myocardial haemodynamics, despite a decrease in cardiac output and an increase in systemic vascular resistance.

PRE-OPERATIVE SPIROMETRY IN THORACIC SURGERY.

All thoracic surgery cases in this clinic during the period from 1954 to 1961, comprising 1332 operations, were analyzed with regard to operative mortality and need for special respiratory care. The results were related to pre‐operative spirometry findings.

Hemodynamic effects in dogs of nitrous oxide‐meperidine and meperidine, respectively, in comparison with nitrous oxide

The aim of this investigation on dogs, was to examine the hemodynamic effects of nitrous oxide (N2O) plus meperidine and of meperidine with room air ventilation, respectively, compared with those of N2O on its own. When meperidine (bolus dose 3 mg ± kg‐1 and continued infusion 4 mg ± kg‐1 ± h‐1) was added to 80% N2O, mean arterial blood pressure fell from about 20 to 10 kPa (150 to 75 mmHg), as a result of a decrease in peripheral vascular resistance, but no compensatory changes in cardiac output were seen. When N2O was withdrawn, during continued meperidine infusion, cardiac output and stroke volume increased, while peripheral resistance remained low. Coronary vasodilation was noted when meperidine was added to N2O, and persisted when N2O was withdrawn. In the pulmonary circulation a different response was found. Here, no effects were observed when meperidine was added to N2O, while pressure and resistance decreased when N2O was withdrawn and meperidine continued.

The Haemodynamic Effects of Adrenergic Receptor Blockade or Stimulation During Nitrous Oxide Anaesthesia in Dogs

The effects of ventilation with normoxic and hyperoxic nitrous oxide on systemic, pulmonary and coronary haemodynamics before and after adrenergic receptor blockade or stimulation were investigated in 15 dogs. To evaluate a blocking or stimulating effect of nitrous oxide on the α‐adrenergic receptors, the animals were given phenoxybenzamine or noradrenaline, respectively. The effects of β‐adrenergic receptor blockade or stimulation were studied after injection of pro‐pranolol or isoproterenol, respectively. The experiments showed that in spite of the lack of α‐receptor blocking properties and despite the tendency to produce β‐receptor blockade, nitrous oxide induced vasodilation. The findings of the present study, together with the increase in cardiac output and peripheral vasodilation, suggest that the cardiovascular effects of nitrous oxide are extra‐adrenergic.