Anaesthesia and Intensive Care

In a prospective double-blind study, single-dose lumbar epidural blockade was administered to 60 healthy patients undergoing lower abdominal surgery, the patients lying in the lateral position only during the time of injection of the local anaesthetic. Solutions used were bupivacaine HCl 0.5%, lignocaine HCl 2% and lignocaine-bupivacaine mixtures in the ratios of 1:3, 1:1 and 3:1 by volume. Data were pooled and analysed for the effects of posture on epidural blockade. Using skin temperature as a criterion of sympathetic blockade, onset of blockade was more rapid and there was more prolonged blockade on the dependent side. Initial onset of sensory blockade was faster on the dependent side by I minute and 3.1 minutes for partial and complete blockade, respectively. Mean duration of sensory blockade was longer in the dependent dermatomes for partial (14, SD 7, minutes, T₆-L₄) and complete blockade (20, SD 6, minutes, T₈-L₃) respectively. Initial onset of complete motor blockade was 5 minutes more rapid on the dependent side, with mean myotome score consistently greater at all time intervals on the dependent side. Our study therefore suggests that a more efficacious sensory and motor blockade could be achieved by lying the patient on the operative side during the administration of the epidural and injection of the local anaesthestic solution close to the operative dermatomes.

Changes in mean arterial pressure (MAP) and plasma catecholamine concentrations in response to endotracheal intubation were examined in 8 patients who had received d-tubocurarine and 10 who had received suxamethonium. MAP fell after induction of anaesthesia and administration of the relaxant by a mean of 11 mmHg in those who had received suxamethonium and 19 mmHg in those who had received d-tubocurarine (p <0.05 for each). MAP rose sharply when the trachea was intubated, by a mean of 29 mmHg for the suxamethonium group, and 35 mmHg for the curare group (p <0.001 for each). A significant rise in plasma noradrenaline was also noted after intubation in each group, 51% (p <0.01) for the suxamethonium group and 28% (p <0.05) for the d-tubocurarine.

The results suggest that the fall in MAP after administration of d-tubocurarine does not attenuate the pressor response associated with intubation.

The safety and efficacy of prolonged infusion of alphaxalone/alphadolone (Alfathesin: Glaxo) was assessed in 20 critically ill patients needing sedation during intermittent positive pressure ventilation in a general intensive care unit. The mean dose of Alfathesin infused was 1542 ml (range: 225 to 4820 ml) over 6.9 days (3 to 16 days) at rates between 5 and 15 ml/hour. Significant increases in plasma urea, creatinine, bilirubin, alkaline phosphatase and white cell count occurred during the infusion, but these were expected from each patient's clinical course. Lipoprotein electrophoresis invariably showed loss of the alpha band and appearance of a densely staining pre-beta band. Four patients had involuntary movements during the infusion and two patients fitted when the infusion stopped. Both had cerebral injuries. Subjective assessment of the quality of sedation was “very good” or “good” in 15 patients and “fair” in five.

A Paediatric Emergency Transport Service has been operating from the Paediatric Intensive Care Unit of the Royal Children's Hospital, Melbourne, for the last three years. The records of the first 158 patients evacuated have been analysed and are reported. Problems relating to the care of the airway and artificial airway have been the most common. The need for careful pre-transport resuscitation and stabilisation is emphasised. The educational role of a transport service both at the time of initial consultation and at the time of retrieval is stressed.

Allocation of nursing staff to patient care in our teaching hospital Intensive Care Unit is based on providing the care considered necessary, bearing in mind the experience of the nursing staff and the care requirements of the patients. A detailed study of the nurse:patient ratio over a two month period has been carried out. It was found that there was considerable variation in both hours of care required and hours of care delivered from shift to shift. The study supported the principles used in staff allocation based on professional judgement, namely the acceptance of a high nurse: patient ratio, with other staff available for special duties, administration and education.

A study of the attitudes of general surgical patients to the management of their postoperative pain showed that although 86% initially expressed satisfaction with their postoperative pain relief, a quarter of these did in fact have moderate, severe or unbearable, unalleviated pain. These, together with those who expressed dissatisfaction with their pain relief, constituted one third of the total number, indicating that a problem of postoperative analgesic management existed in the hospital. As a result, techniques of continuous intravenous infusion of narcotics and more frequent use of regional analgesia have been introduced.

Morphine sulphate 5 mg and placebo administered epidurally after caesarean section under epidural analgesia were compared in a double-blind fashion.

Morphine was significantly superior to placebo for pain relief, duration of pain relief, and reduction of parenteral narcotic requirements. Pruritis was the most commonly encountered side-effect. There was no statistical difference between morphine and placebo in the incidence of urinary catheterisation, vomiting, nausea, dizziness or drowsiness. No serious respiratory depression requiring treatment was observed.

The reliability in providing a continued venous route to the circulation is compared between a winged needle (Abbott “Butterfly — 23 INT”) and a plastic catheter (Jelco Teflon “Catheter Placement Unit”, 22 gauge). The catheter remained within the vein in all cases and had a much lower incidence of total obstruction during the study period. Where an intravenous infusion is not in place, a plastic catheter provides a more reliable access route to the circulation than does a winged needle.

Gastric pH values were studied prior to, and up to, ninety minutes after an intravenous injection of cimetidine 200 mg given before general anaesthesia, in twenty surgical patients, all with a gastric pH < 3.5. At thirty, sixty and ninety minutes, sixteen, eighteen and twenty patients had a gastric pH>3.5 respectively. In conclusion, the results of the present study indicate that cimetidine 200 mg given intravenously 90 minutes before surgery will reduce the hazard of chemical pneumonitis should stomach content be aspirated.

Cardiac output measurements determined by dye dilution, iced-injectate thermodilution and room temperature thermodilution were compared in man in order to assess the random error of each method and to examine the systematic error of both thermodilution methods in comparison with dye dilution.

Results showed that random error was greatest with room temperature thermodilution and least using iced thermodilution. Iced thermodilution correlated well with dye dilution, tending to overestimate cardiac output only at low flows. Room temperature thermodilution, however, overestimated cardiac output by up to 25% in the clinically important range and more so at low cardiac output.

Regular evaluation of the pH of aspirated gastric juice is an important part of the routine prevention of the stress ulceration syndrome. This study has examined the use of commercially available pH paper for this purpose. Both clear buffer solutions and samples of gastric aspirate were used to assess the reliability of four products, Merck Universal pH Indicator strips (Art. 9535), Lyphan Universal pH Indicator paper, Whatman Wide Range pH paper and Macherey-Nagel Universal pH paper. The results show that the Merck strips and Lyphan paper are very reliable for measuring gastric aspirate pH and that intensive care nursing staff can make accurate observations when using these papers.

We developed an apparatus and technique for the simultaneous measurement of functional residual capacity and oxygen uptake (V̇O₂) for use in intensive care unit (ICU) patients. The accuracy of the functional residual capacity measurement was proven using an in vitro lung model and the reproducibility of this measurement was established by use in ICU patients. We tested the accuracy of the V̇O₂ measurement in comparison with two other methods in common use among ICU patients and our method proved accurate. We conclude that this technique for measurement of functional residual capacity and V̇O₂ is highly accurate and easily applied to patients on any mode of mechanical ventilation.

A new endotracheal tube for neonatal use is described in which a 5FG pressure measuring catheter is attached to the convex surf ace of a conventional polyvinylchloride endotracheal tube. Using this modified endotracheal tube intratracheal pressure can be measured. Preliminary studies were undertaken in three infants. It was found that at high ventilatory rates (above 80/min) pressures measured within the trachea were different from those measured in the ventilator circuit.