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Raised intra-ocular pressure secondary to alterations in plasma oncotic pressure has been implicated in the development of optic neuropathy after cardiopulmonary bypass. Patients presenting for open heart surgery received either crystalloid (n = 9) or colloid (n = 10) priming solutions for cardiopulmonary bypass. No differences in intra-ocular pressure or plasma oncotic pressure occurred between the groups before the onset of cardiopulmonary bypass. Five minutes after the start of bypass the median intra-ocular pressure increased to 31 mmHg in the crystalloid group compared with 13 mmHg in the colloid group (p < 0.05). At the same time plasma oncotic pressure decreased from approximately 20 mmHg in both groups to 10.6 mmHg with crystalloid and 15.7 mmHg with colloid primed cardiopulmonary bypass solutions (p < 0.05). Over the following hour of cardiopulmonary bypass, intra-ocular pressure and plasma oncotic pressure tended to return towards their pre-cardiopulmonary bypass values. Changes in plasma oncotic pressure, through fluid shifts, may have contributed towards this unexpected increase in intra-ocular pressure with crystalloid primed cardiopulmonary bypass.

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During cardiopulmonary bypass, isoflurane may have beneficial effects on systemic oxygen uptake and vascular resistance. For this reason, the effects of isoflurane during low-flow (1.6 L/min/m2), hypothermic (27 degrees to 29 degrees C) cardiopulmonary bypass on systemic hemodynamics and oxygen uptake were studied in 20 patients in a cross-over experiment. Mean arterial and central venous pressures were measured during two consecutive periods of 10 minutes' duration. Blood samples were aspirated at the end of each period from the arterial and venous lines and analyzed for oxygen content. The concentration of isoflurane in the arterial samples was also determined. Systemic oxygen uptake and vascular resistance were calculated. Isoflurane had no significant effect on systemic oxygen uptake. Significant inverse relationships between blood isoflurane concentration and both mean arterial pressure and systemic vascular resistance were found. It is concluded that isoflurane is a vasodilator under the abnormal conditions of hypothermic cardiopulmonary bypass, but has no effect on systemic oxygen uptake.

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During hypothermic cardiopulmonary bypass, the effects on hemodynamic variables of alternating pump flow rate between 1.5 and 2.0 L.min-1.m-2, flow character between nonpulsatile and pulsatile perfusion, and acid-base management between pH- and alpha-stat control were studied in a crossover factorial experiment. Twenty-four patients who were undergoing elective coronary artery bypass grafting were studied during stable hypothermic (27 degrees to 29 degrees C) cardiopulmonary bypass. A minimum of two (when time allowed, three) consecutive 10-minute periods (period 1, 2, or 3) were investigated. Only stage of the study period during cardiopulmonary bypass, flow rate, and interaction between stage and acid-base management were found to have significant effects on mean arterial pressure. In all patients, there were average increases in mean arterial pressure from period 1 to period 2 of 9.4 (95% confidence interval 5.8, 13.0) mm Hg, from period 2 to period 3 of 6.3 (95% confidence interval 1.2, 11.4) mm Hg, and from period 1 to period 3 of 15.7 (95% confidence interval 10.6, 20.9) mm Hg. At 2.0 L.min-1.m-2, mean arterial pressure was 7.2 (95% confidence interval 1.6, 12.9) mm Hg higher than at 1.5 L.min-1.m-2. Peripheral vascular resistance was significantly affected only by stage and flow rate. There were, in all patients, mean increases in peripheral vascular resistance from period 1 to period 2 of 239 (95% confidence interval 135, 343) dynes.sec.cm-5, from period 2 to period 3 of 85 (-64, 234) dynes.sec.cm-5, and from period 1 to period 3 of 324 (95% confidence interval 175, 473) dynes.sec.cm-5. At 1.5 L.min-1.m-2, the peripheral vascular resistance was 316 (95% confidence interval 152, 480) dynes.sec.cm-5 higher than at 2.0 L.min-1.m-2. Alteration in flow rate, but not flow character or arterial pH, had a significant effect on peripheral vascular resistance. It is hypothesized that the increase in peripheral vascular resistance during the course of cardiopulmonary bypass results from an active capillary mechanism, whereas the increase that is associated with reduction in flow rate reflects a passive mechanism. The increase in peripheral vascular resistance with decrease in flow rate indicates impaired tissue perfusion, unlike that occurring with stage.

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A factorial experiment was undertaken to study the effects on systemic oxygen uptake of alteration in flow rate between 1.5 and 2.0 L.min-1.m-2, flow character between nonpulsatile or pulsatile perfusion, and acid-base management between attempted pH and alpha stat control during hypothermic cardiopulmonary bypass. Twenty-four patients undergoing elective coronary bypass were studied. After 10-minute periods of stability at moderate hypothermia (28 degrees +/- 1 degrees C), blood samples were aspirated from the arterial and venous lines. Samples were analyzed for oxygen content, saturation, and tension, pH, base excess, and lactate. Systemic oxygen uptake was significantly greater at 2.0 than 1.5 L.min-1 m-2 by 18 (7, 30) ml.min-1.m-2, whereas it was not significantly affected by change in flow character (-4[-16, 7] ml.min-1.min-2) or arterial pH (-2 [-12, 8] ml.min-1.m-2 per 0.1 pH unit). Venous oxygen tension, saturation, and content were significantly increased at the higher compared with the lower flow rate (p less than 0.05), whereas arterial oxygen tension and oxygen extraction were not. Increases in arterial oxygen content and saturation from low to high flow rates were marginally nonsignificant (F = 4.08, critical value = 4.17; F = 3.99 critical value = 4.21). Base excess was significantly affected by alteration in arterial pH but not flow rate, flow character, or stage (p less than 0.05). Lactate concentrations were unaffected by flow rate, flow character, or arterial pH, but there was a small but significant overall decrease during the course of cardiopulmonary bypass (p less than 0.05). Reasons why systemic oxygen uptake was affected by flow rate but not by flow character or arterial pH are discussed. A flow rate of 1.5 L.min-1.m-2 during cardiopulmonary bypass with moderate hypothermia results in a less than maximal systemic oxygen uptake.

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Forty-five patients in four groups undergoing orthopaedic, upper abdominal, prolonged or cardiac surgery received a constant rate i.v. infusion of fentanyl 100 micrograms h-1, for 24 h starting 2 h before surgery. A single bolus dose was given i.v. at the induction of anaesthesia. Plasma fentanyl concentrations, measured by radioimmunoassay were between 1 and 3 ng ml-1 until the infusions were discontinued. Clearance of fentanyl was decreased in the cardiac surgery group only. The elimination half-life was 7.3-9.7 h. This simple regimen produced effective analgesia.

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Hydralazine, labetalol, methyldopa, minoxidil, prazosin, and placebo were compared when added by random allocation to atenolol 100 mg and bendrofluazide 5 mg daily in a series of 238 hypertensive patients inadequately controlled by the beta blocker-diuretic combination. Atenolol was withdrawn in those allocated to labetalol, and minoxidil was given only to men. The order of acceptability was: placebo, hydralazine, prazosin, methyldopa, minoxidil, labetalol. Minoxidil was more effective than the other active drugs, which had similar potency to one another. All the active agents were more effective than placebo. Hydralazine was the most generally suitable third drug, with prazosin a close second. Minoxidil was especially effective in patients with less severe hypertension but the same regimen caused fluid retention in those with more severe disease. Labetalol should probably be introduced at a low dose (150 mg daily) even when replacing full doses of a previously administered beta blocker.

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A method of protamine titration, with the use of the 'Haemochron 400' system for reversal of heparinisation after cardiopulmonary bypass is described. Twenty-three patients, average age 47 years, undergoing this procedure for either valve replacement or coronary artery bypass grafting were studied. Accurate reversal of heparinisation was achieved using comparatively small doses of protamine. A linear relationship between the dose ratio of protamine and heparin and the time interval between their respective administrations was defined where only a single dose of heparin had been administered.

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Fifty-five patients presenting with fractured neck of femur were randomly allocated to either a standard general anaesthetic or spinal block in the lateral position combined with light sedation. The comparability of the two groups was established. There was little difference in the intra-operative course of postoperative morbidity in the two groups. There was a statistically significant difference in post-operative mortality between two groups, the general anaesthetic group showing a much higher mortality than the spinal group.

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In a double blind trial, 50 male chronic alcoholic patients were treated with either fenfluramine in a dose of 60 mg or 120 mg daily, or with identically prepared placebo tablets. Patients were interviewed on admission to the trial and then at four-weekly intervals for a period of one year and blood levels of delta-aminolaevulinic acid dehydratase (ALAD) and gamma-glutamyl transpeptidase (gammaGT) and fenfluramine were determined. The efficacy of fenfluramine at the two dose levels was compared with placebo on the basis of the number of lapses indicated by the clinical history and also by alterations in the biochemical indices. Twenty-seven patients completed the period of observation, there being 9 in each of the three groups. Those receiving 120 mg fenfluramine daily showed significantly fewer lapses than either of the other two groups (p less than 0-01) on biochemical but not on clinical criteria. Overall assessment revealed that 3 of the 9 patients receiving the high dose of fenfluramine had a good result during the period of the trial, but there were none in the 60 mg group or in those receiving placebo. More extensive trials of fenfluramine in the treatment of chronic alcoholism are indicated.

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Rate constants for reactions in flowing solutions in soil can be calculated from extents of reactions as functions of depth, rates of flow, effective biomass of microbes and independent measurements of hydrodynamic dispersion. Constants have been calculated from data in the literature and are shown to be arbitrary unless all of these quantities have been evaluated. Good agreement of constants obtained in laboratory columns and in the field have been obtained for nitrification and denitrification in a few cases.

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Betting odds for possible carriers of haemophilia have been calculated using data derived from normal and known carrier populations. For each possible carrier the concentration of factor VIII-related antigen and factor VIII biological activity was measured and used to determine the probability of the individual being a carrier. The calculations indicated that, of the 32 possible carriers, 11 were likely to be normal (odds of more than 5:1) while 11 were likely to be haemophilia carriers (again odds of more than 5:1).

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