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Biomedical subjects

F Reynolds

Publications and source records attributed to F Reynolds.

At least 19 recordsLinked to original sources
PubMed1992

Elimination of bupivacaine and pethidine from the rabbit feto-placental unit.

Bupivacaine 12.5 mg and pethidine 12.5 mg were administered as an i.v. infusion over 80 min in 15 near-term pregnant New Zealand white rabbits. After the infusion, pups were removed via individual hysterotomies every 30 min. Bupivacaine and pethidine were measured by gas chromatography in amniotic fluid, placenta, fetal plasma, fetal brain and maternal plasma, sampled as each fetal sac was opened. Pethidine was cleared from all compartments more rapidly than bupivacaine and for both drugs elimination rates were maternal plasma > placenta > amniotic fluid > fetal brain > fetal plasma. Concentrations of both drugs in fetal plasma correlated significantly only with those in fetal brain and not with those in maternal plasma, placenta or amniotic fluid, while there were positive correlations between the last three compartments. Nested analysis of covariance showed that only maternal plasma and placental concentrations of the two drugs decreased significantly with time. Maternal plasma half-lives for pethidine and bupivacaine were 1.0 and 2.0 h, and placental half-lives 1.9 and 2.5 h, respectively. The apparent fetal plasma half-life of pethidine was 9.9 h while there was apparently no net elimination of bupivacaine from fetal plasma.

Animals↗
PubMed1992

Upper oesophageal sphincter pressure and the effect of cricoid pressure.

Upper oesophageal sphincter pressure has been measured in 24 patients with a sleeve device. The median sphincter pressure when awake was 38 mmHg, and when anaesthetized and paralysed was 6 mmHg. After tracheal intubation, cricoid pressure was applied at measured values between 5 and 50 N using a hand-held cricoid yoke while the sphincter pressure was recorded in two head and neck positions: with and without a standard intubating pillow with neck support. A cricoid force of 40 N increased sphincter pressure to above 38 mmHg in all the patients and the use of the pillow did not alter this effect. With the application of cricoid pressure, operating department assistants raised sphincter pressure to above 38 mmHg in only 50% of patients. Laryngoscopy made little difference to the effect of cricoid pressure except in one patient in whom it reduced the sphincter pressure by 27 mmHg.

Adult↗
PubMed1992

Upper oesophageal sphincter pressure and the intravenous induction of anaesthesia.

The upper oesophageal sphincter can prevent regurgitation of oesophageal contents into the pharynx following gastrooesophageal reflux in the awake patient. Upper oesophageal sphincter pressure was recorded with a Dent sleeve after hypnosis with midazolam (n = 7) and also during the rapid intravenous induction of anaesthesia with thiopentone (n = 16) or ketamine (n = 7). Thiopentone decreased mean (SD) sphincter pressure from an awake value of 43 (19) to 9 (7) mmHg (p less than 0.001) and midazolam from 38 (25) to 7 (3) mmHg (p less than 0.02). Mean (SD) sphincter pressures before and after ketamine were not significantly different at 29 (15) and 32 (21) mmHg respectively. After suxamethonium mean (SD) sphincter pressure in all patients (n = 30) was 7 (4) mmHg. Laryngoscopy (n = 30) caused a small increase in mean (SD) sphincter pressure to 13 (10) mmHg (p less than 0.001). Thiopentone caused a rapid fall in upper oesophageal sphincter pressure which usually started before loss of consciousness. These findings have implications for the timing of cricoid pressure application.

Adult↗
PubMed1992

Upper oesophageal sphincter pressure during inhalational anaesthesia.

Upper oesophageal sphincter pressure was recorded with a Dent sleeve in 30 patients breathing nitrous oxide, oxygen and halothane. Twenty-three patients, after thiopentone induction, received suxamethonium and had their trachea intubated either before (group A, n = 11), or after (group B, n = 11), a study period of inhalational anaesthesia. Group C (n = 8) received an inhalational induction. Mean (SD) sphincter pressure after loss of consciousness was 8 (7) mmHg (group A), 6 (5) mmHg (group B) and 24 (13) mmHg (group C) increasing to 19 (7) mmHg in group A immediately after intubation. With an end-tidal halothane concentration of 1.5%, mean sphincter pressure in group B, 16 (7) mmHg, was significantly lower than in group A, 45 (21) mmHg (p < 0.001) and group C, 27 (14) mmHg (p < 0.05). Halothane had no dose-related effect on sphincter pressure. Insertion of a laryngeal mask in group C (n = 7) had no significant effect on sphincter pressure. Induction and maintenance of anaesthesia with halothane, unlike thiopentone or suxamethonium, maintained a degree of upper oesophageal sphincter tone, although three patients in this study had sphincter pressures of less than 10 mmHg and would therefore have been at risk of regurgitation in the presence of gastro-oesophageal reflux.

Adult↗
PubMed1991

Lumbar epidural diamorphine following thoracic surgery. A comparison of infusion and bolus administration.

Twenty-two patients received a single dose of diamorphine 5 mg through a lumbar epidural catheter before thoracic surgery. The patients were transferred after surgery to a high dependency unit where they were allocated randomly to receive either an infusion of epidural diamorphine at a rate of 1 mg/hour (group 1) or bolus doses of epidural diamorphine 5 mg on demand (group 2). There was no statistically significant difference between the groups in visual analogue pain scores in the first 18 postoperative hours. Arterial carbon dioxide tension was elevated in both groups and was consistently higher in group 1 than in group 2, with a statistically significant intergroup difference 12 hours after operation. Respiratory rate was not a useful index of respiratory depression. The commonest nonrespiratory side effect was urinary retention, but the incidences of this and other minor side effects were similar in the two groups.

Adult↗
PubMed1991

Ropivacaine.

Explore the source record for details and available documents.

Amides↗
PubMed1991

A comparison of serum and saliva paracetamol concentrations.

The relationship between serum and saliva paracetamol concentrations was investigated in twenty healthy volunteers. The plasma and saliva drug concentrations showed a significant correlation (r = 0.67). However the agreement between the two methods of measurement was poor with limits of agreement of -15.3 mg l-1 to +15.9 mg l-1 with mean sample values of 19.2 and 19.5 mg l-1 for plasma and saliva, respectively.

Acetaminophen↗
PubMed1990

The subdural space: the third place to go astray.

Subdural placement of the tip of the Tuohy needle or epidural catheter may account for many unexpected complications of attempted epidural blockade, for example, 'unexplained' headache, false-negative aspiration test down needle or catheter, false-negative test dose, unilateral block, delayed total spinal and neurological sequelae, as well as profound block of delayed onset that is characteristic of subdural blockade. Cases are reported in support of this hypothesis.

Adult↗
PubMed1990

Peri-operative care in restrictive respiratory disease.

A total of 139 of 473 severely disabled, mainly ventilator-dependent patients required some form of surgery. Such patients require surgery more frequently than normal individuals, both because of their disability and because even minor unrelated disorders superimposed on permanent disability cause greater handicap. We report the peri-operative management and postoperative complications of 142 operations on 83 patients between 1982 and 1987. A simple inhalational anaesthetic technique was used; opioids and muscle relaxants were seldom given. Negative pressure ventilation was employed in the postoperative period when appropriate, and was combined with vigorous chest physiotherapy. There were three peri-operative deaths, but the overall death rate in the patients who underwent surgery was no greater throughout the study period than in those who did not require surgery. We believe that an aggressive surgical approach is appropriate in severely disabled, ventilator-dependent patients.

Adult↗
PubMed1990

Effect of umbilical perfusate pH and controlled maternal hypotension on placental drug transfer in the rabbit.

The purpose of this study was to explore the effect that fetal acidosis and poor maternal placental blood flow may have on the rate of passage across the placenta of drugs commonly used in labor: bupivacaine and meperidine. The rabbit placenta perfused in situ on the fetal side was used, and antipyrine (phenazone) was included as an index of placental exchange and of maternal placental flow. Bupivacaine and meperidine (both 1.25 mg/mL) and antipyrine (4 mg/mL) were infused into a maternal external jugular vein, at 3 mL/h, after loading, in seven anesthetized does. A single placenta in each doe was perfused via the umbilical arteries with Krebs' bicarbonate buffer at pH 7.5 (phase 1), 7.0 (phase 2), and 7.5 (phases 3-5). During phase 4 maternal blood was withdrawn so as to reduce maternal arterial pressure by 35%, and in phase 5 it was reinfused. Concentrations of drugs were measured during each of the five phases in maternal arterial plasma (Cma) and in the effluent perfusate collected from the umbilical vein (Cuv). From these data, placental clearance rates (Cuv x umbilical flow/Cma) were calculated for each drug at each phase. Clearance of bupivacaine and meperidine increased (P less than 0.03) during phase 2, whereas that of antipyrine did not. Clearance of meperidine and antipyrine, but not of bupivacaine, decreased during phase 4. If these results can be extrapolated to the clinical situation, they suggest that the adverse effects of drugs may well be exacerbated in the presence of fetal compromise.

Anesthesia, Obstetrical↗
PubMed1989

Intradermal hepatitis B immunization with yeast-derived vaccine: serological response by sex and age.

The efficacy and acceptability of yeast-derived recombinant hepatitis B vaccine given by the intradermal route was investigated in 221 health care volunteers. Two hundred and sixteen received a full course of three doses of vaccine. Only one subject was withdrawn because of a significant adverse reaction (psoriasis). The vaccine stimulated an antibody response in 81%. The response to the vaccine was better in women than in men (87% compared with 71%, p = 0.007) and in women below the age of 40 years compared with older women (94% compared with 76%, p = 0.01). For men the response showed a sequential decline with age for each decade (90% responders from age 29 or less, 72% aged 30-39 and 65% aged 40 or more, p = 0.04). Retrospective enquiry showed that over 90% had found the intradermal route acceptable and 59% would prefer vaccine by the intradermal route in preference to intramuscular notwithstanding local reactions. Although the seroconversion rate was of a high order in younger women the antibody titres were not high with only 9 of 215 recipients developing titres greater than 1000 mIU/ml, a level which could be expected to ensure prolonged immunity. A fourth intradermal dose of vaccine given to 60 volunteers who had shown a low response (less than 38 mIU/ml) or no serological response to a three-dose course stimulated a good booster effect (to 150-600 mIU/ml) in only 5 (8%).

Adult↗