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Biomedical subjects

P J Simpson

Publications and source records attributed to P J Simpson.

106 records · Page 6Linked to original sources
PubMed1982

Prolonged local analgesia for inguinal herniorrhaphy with bupivacaine and dextran.

In a randomised double-blind trial 40 patients undergoing unilateral inguinal herniorrhaphy were each locally anaesthetised with one of a series of 8 solutions. These contained bupivacaine, both with and without adrenaline, mixed with an equal volume of dextran 40, dextran 70, dextran 110, or saline. Significant prolongation of local analgesia was achieved with high-molecular-weight dextran and this was most consistently obtained when the solution used contained adrenaline. The possible influence of the pH of the solutions used, together with the ways in which dextran may affect the duration of action of bupivacaine are discussed.

Anesthesia, Local↗
PubMed1981

Lorazepam in intensive care.

The suitability of lorazepam as a sedative for use in intensive care has been critically evaluated in 36 severely ill patients. The efficacy of lorazepam has been evaluated by regular measurements of both cardiovascular and neurological status as well as by the nursing staff directly involved with the care of the patients. A variety of patients have received lorazepam for sedation both while on intermittent positive pressure ventilation and when breathing spontaneously. The benefits of the predictable and even sedation produced by a long-acting drug of this nature are discussed. Particular attention has been paid to the possibility of accumulation of lorazepam in a similar way to that of diazepam, and the relative advantages of the two drugs for use in the intensive care situation have been compared.

Adolescent↗
PubMed1981

Studies on premedication and ventilatory responses to minaxolone.

The effect of three premedications on induction, maintenance and recovery characteristics of minaxolone as a supplement to nitrous oxide and oxygen anesthesia were studied in 70 patients. Morphine and atropine premedication provided superior operative conditions with fewer side-effects when compared with atropine alone or diazepam and atropine. Recovery was significantly longer after minaxolone compared with a similar group of patients given Althesin. The ventilatory responses to the induction of anesthesia with minaxolone were measured in 25 patients. All patients showed an increase in respiratory frequency and a decrease in tidal volume. This effect was most marked in the group premedicated with diazepam and atropine.

Adult↗
PubMed1980

Enflurane in outpatient paediatric dental anaesthesia. A comparison with halothane.

Enflurane and halothane were compared as volatile supplements to nitrous oxide anaesthesia for 80 children presenting for outpatient dental extractions. Induction and maintenance of anaesthesia were comparable and satisfactory with both agents, but recovery of consciousness was significantly quicker following enflurance anaesthesia. Full recovery from either enflurance or halothane was of similar duration.

Ambulatory Surgical Procedures↗
PubMed1980

Minaxolone or Althesin supplemented by nitrous oxide. A study in anaesthesia for short operative procedures.

Minaxolone citrate, a new water-soluble steroid intravenous anaesthetic, has been compared with Althesin as an induction agent and subsequently intermittently supplemented by nitrous oxide and oxygen alone for anaesthesia for short surgical procedures. Short term recovery following Minaxolone was significantly slower than after Althesin, but 1 h after the end of anaesthesia, no differences could be detected between the two groups of patients. Minaxolone, given by intravenous increments to supplement nitrous oxide following an induction dose of 0.5 mg/kg, appears to provide satisfactory anaesthesia for short surgical procedures.

Adult↗
PubMed1979

Some physiological and metabolic effects of sodium nitroprusside and cyanide in the dog.

The cardiovascular and acid-base changes following equivalent i.v. bolus doses of sodium nitroprusside (SNP) and potassium cyanide (KCN) have been studied in two groups of anaesthetized dogs. In a third group, the metabolic changes produced by i.v. infusion of SNP 1.5 mg kg-1 at a constant rate over 1 h have been studied. In contrast to a decrease in arterial pressure following SNP, hypertension and tachycardia occurred after the administration of KCN, with hyperventilation and an increase in packed cell volume. During infusion of SNP, increases in plasma cyanide concentrations were associated with an increase in arterial base deficit, plasma lactate and excess lactate and a decrease in oxygen consumption. The occurrence of lactic acidosis with SNP 1.5 mg kg-1 suggests that this may be the maximum safe dose for short term infusion. However, all these changes reversed spontaneously following discontinuation of SNP, indicating that base deficit is an adequate metabolic monitor during administration of SNP.

Acid-Base Equilibrium↗
PubMed1979

Metabolism of sodium nitroprusside and cyanide in the dog.

Blood cyanide (HCN) and thiocyanate (SCN) concentrations were measured at intervals in anaesthetized dogs given bolus doses of sodium nitroprusside (SNP) 1 mg kg-1 or potassium cyanide 1.07 mg kg-1 and in animals infused with SNP 1.5 mg kg-1 for 1 h. Cyanide appeared rapidly in the red cells to give peak concentrations which accounted for more than 90% of the total blood HCN. A delay between the peak plasma and red cell HCN concentrations confirmed that some of the SNP was degraded in the plasma. Comparison of HCN and SCN concentrations with those measured previously in patients receiving an infusion of SNP suggests that the degradation of SNP and detoxication of HCN may be more rapid in the dog. The various pathways of HCN detoxication are discussed in relation to the reduced formation of SCN in dogs receiving SNP compared with those receiving KCN.

Animals↗
PubMed1976

Cyanide and thiocyanate concentrations following sodium nitroprusside infusion in man.

Twenty-six patients, receiving an infusion of sodium nitroprusside (SNP) during surgery, had considerable increases in both red cell and plasma cyanide concentration, but only small changes in plasma thiocyanate concentration. There was a linear relationship between both plasma and RBC cyanide concentrations and the total dose of SNP. The expired cyanide concentration followed the changes in the plasma. We believe that the development of metabolic acidosis, and the recent fatalities involving SNP, are attributable to histotoxic hypoxia as a result of excessive plasma concentrations of cyanide. On the basis of our results, we recommend that the total dose of SNP should not exceed 1.5 mg/kg during short-term infusions and that the plasma cyanide should not exceed 300 nmol%. Plasma thiocyanate concentrations are, in general, an unreliable indication of extent of exposure to cyanide, although they may become important during long-term infusions.

Adolescent↗
PubMed1967

Relationships of x-irradiation to the enhancement of Candida albicans infections.

Preirradiation significantly reduced the number of Candida albicans cells required for the ld(50) of experimentally infected mice. The start and extent of recovery of total leukocytes of preirradiated infected mice were proportional to the dose of X rays administered. During 10 days postinfection, heterophils of infected mice preirradiated with 400 R recovered to levels above unirradiated, uninfected controls but did not exceed those of unirradiated, infected animals. On the other hand, the more radiosensitive lymphocytes were depressed greatly, and a limited recovery below normal values was obtained. The lymph to heterophil ratio of uninfected mice irradiated with 400 R recovered to normal values by 11 days postirradiation. However, decreases in the ratio of unirradiated or X-irradiated infected mice showed little recovery. During 6 to 10 days postinfection, a reduction in microhematocrit values after a dose of 400 R alone was not observed when a C. albicans infection was superimposed on X-irradiated mice. This difference was not due to changes in the red blood cell volume which was decreased by 400 R with or without infection, but was attributed to a greater decrease in plasma volume caused by a combination of X irradiation and infection. Reticulocyte counts indicated that recovery from the significant decrease in erythrocyte production caused by 400 R was retarded by a progressive infection. Elevated total serum protein of unirradiated mice at 6 days after infection was attributed to increases in alpha- and beta-globulins. A dose of 400 R limited but did not prevent an increase alpha- and beta-globulins upon subsequent infection. Candida species infection or 400 R or both did not greatly affect the concentration of gamma-globulins. The albumin to globulin ratio of irradiated, infected mice was intermediate between those ratios found after X irradiation or infection.

Animals↗
PubMedDate not supplied

Canine myocardial reperfusion injury: protection by a free radical scavenger, N-2-mercaptopropionyl glycine.

Oxygen-derived free radicals and their metabolites may contribute to the extension of irreversible cellular injury, which occurs on reperfusion of the previously ischemic myocardium. Therefore, therapy directed against the toxic effects of reactive oxygen species may provide protection to the ischemic myocardium, which undergoes subsequent reperfusion. We evaluated the effectiveness of N-2-mercaptopropionyl glycine (MPG), a free radical scavenger, to limit the extent of irreversible injury resulting from 90 min of ischemia followed by 6 h of reperfusion in a canine model of myocardial infarction. In three groups of dogs, MPG (20 mg/kg) was administered as a constant infusion into the left atrium. Group I received MPG for 2 h, starting 15 min before occlusion of the left circumflex coronary artery and ending 15 min after reperfusion. Group II received MPG for 1 h, starting 15 min before reperfusion. Group III received MPG for 1 h beginning 45 min after reperfusion. Each group was compared with its respective saline control group. Infarct size was reduced by 35% in Group I (32.2 +/- 5.1% vs. 47.7 +/- 3.4% of the area at risk, p less than 0.05) and Group II (31.4 +/- 3.6% vs. 47.5 +/- 5.1% of the area at risk, p less than 0.025) in comparison with the saline treated control animals. In contrast, in Group III infarct size did not differ significantly from the saline-treated control group (45.9 +/- 3.3% vs. 47.7 +/- 3.5% of the area at risk). The percent of left ventricle at risk did not differ among the groups. The beneficial effects of MPG could not be explained on the basis of hemodynamic differences. In addition, MPG did not influence regional myocardial blood flow. In vitro studies indicated that MPG effectively scavanges O2- generated by the hypoxanthine-xanthine oxidase reaction, as well as by PMA-activated polymorphonuclear leukocytes. Based on these observations, we propose that MPG exerts its beneficial effects by protecting against free radical-mediated damage during the early phase of reperfusion.

Amino Acids, Sulfur↗