A SIMPLE SYSTEM FOR ADMINISTERING INTERMITTENT MANDATORY VENTILATION (IMV) WITH THE OXFORD VENTILATOR

A circuit has been devised enabling intermittent mandatory ventilation(IMV) to be delivered from an Oxford ventilator. Two methodsfor delivering oxygen to the system are described. The circuitis constructed from inexpensive components and only one oxygenflowmeter is required. No modifications to the ventilator arenecessary.     

THE THYROID AND CALCIUM HOMEOSTASIS IN MAN : EVALUATION BY CALCIUM INFUSION

Nine normal subjects, and five patients with primary thyroid failure, were infused with calcium gluconate solution (0.6 mEq of calcium per kilogram of body weight) for three hours. Serum calcium and magnesium levels were measured during the next 24 hours. The mean rise in serum calcium level in both treated and untreated patients with thyroid failure was significantly greater than the mean control levels after the fourth hour, and the elevation persisted at 24 hours. No additional abnormality was seen in subjects who also lacked parathyroid tissue, although in one patient with primary hypoparathyroidism alone a similar rise was seen. There were no significant changes in serum magnesium level in any of the patients studied. The results suggest that thyrocalcitonin normally acts in man to restore the serum calcium to normal after its experimental elevation. The clinical implications of this are discussed.     

RELATIONSHIPS BETWEEN INSPIRED OXYGEN CONCENTRATION AND VENOUS ADMIXTURE DURING NITROUS OXIDE-OXYGEN-HALOTHANE ANAESTHESIA

The inspired oxygen concentration (Fl_O²) was changed on 43 occasionsat about 30-min intervals in 13 patients during artificial ventilationwith mixtures of nitrous oxide (N₂O), oxygen and halothane.Ventilator settings remained unchanged for each patient andat the end of each period, samples of arterial and central venousblood (and, in six patients, pulmonary arterial blood) and inspiredand expired gases were collected. Oxygen tension was measuredwith a dedicated electrode shown to be unaffected by N₂O. Venousadmixture (Qva/Qt) was calculated at each Fl_O². There was ahighly significant correlation between the direction of changeof Fl_O² and that of Qva/Qt, irrespective of whether Fl_O² increasedor decreased. In 10 patients, there was a progressive increasein Qva/Qt as Fl_O² increased above 40%, and in all patients Qva/Qton nearly 100% oxygen was greater than that measured at thenext lowest concentration (60-80%). These results are at variancewith the pattern of behaviour predicted from the "critical Va/Q"theory and support the concept of an oxygen-dependent redistributionof perfusion. ^*Present address: Department of Anaesthesia, Prince Henry Hospital,Sydney, Australia     

PEPTIC ULCER: PATHOGENSIS,HEALING AND ANTI-ULCER DRUGS

Abstract To investigate the possible absorption and deposition of bismuth or aluminium from agents used in the treatment of peptic ulcers, we have measured levels of bismuth and aluminium in the liver tissue of 15 patients undergoing elective liver biopsy and in the cerebrospinal fluid (CSF) of 15 patients undergoing elective myelography after administration of standard therapeutic doses of tripotassium dicitrato bismuthate (TBS), sucralfate or aluminium hydroxide for 1 month. Aliquots of liver or CSF were separated and levels of both aluminium and bismuth were assayed in each sample by atomic absorption spectrophotometry. The group who received TBS had significantly higher liver bismuth levels than the other two treatment groups, but there was no significant difference in CSF bismuth levels among the three groups. There was no significant difference in either liver or CSF aluminium levels among the three treatment groups. We conclude that tissue accumulation of bismuth may occur after short-course therapy with colloidal bismuth, although there is no evidence of CNS accumulation of bismuth in the present study.     

EXTRADURAL ADMINISTRATION OF MORPHINE AND BUPIVACAINE: A controlled comparison

Analgesia, following operation, was provided by the extraduraladministration of morphine or bupivacaine in 24 patients, ina double-blind, randomized, cross-over study. Observations weremade of vital signs, peak expiratory flow rate (PEFR), qualityand duration of pain relief and the occurrence of adverse effects.Vital signs were little affected by morphine, but hypotensionrequiring active treatment occurred in three patients followingthe administration of bupivacaine. The PEFR was improved aboutequally by each drug, and the improvement was significant comparedwith control values (P > 0.001). Pain relief as judged bythe linear analogue scale was significantly better followingbupivacaine than after morphine (P > 0.001), but the painscore system, while showing effective pain relief in most patientswith both drugs, did not demonstrate a significant differencebetween them. The duration of effect of morphine was significantlylonger (P > 0.05) than that of bupivacaine. Adverse effects,other than bupivacaine-induced hypotension, were not serious.