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Biomedical subjects

F Reynolds

Publications and source records attributed to F Reynolds.

At least 91 records · Page 5Linked to original sources
PubMed1993

Effect of epidural opioids on gastric emptying in labour.

The effect of epidural opioids on gastric emptying was studied in 36 women in labour. Women who had received one dose of epidural bupivacaine were randomised to receive 10 ml of bupivacaine 0.25% alone (n = 8) with fentanyl 50 microg (n = 8) or with diamorphine 2.5 mg (n = 8), or 10 ml of bupivacaine 0.125% alone (n = 4) or with fentanyl 100 microg (n = 4) or with diamorphine 5 mg (n = 4) when they first requested a top-up. Mean+/-SD fentanyl concentrations measured at delivery were, in maternal venous plasma (MV) 0.72+/-0.19 ng/ml and in umbilical venous plasma (UV) 0.75+/-0.3 ng/ml. The mean dose-delivery interval was 280 min (range 107-608 min) and there was a negative correlation between UV/MV and dose-delivery interval. Gastric emptying was assessed by measuring paracetamol absorption following an oral dose of 1.5 g given 30 minutes after the study top-up. Time to peak plasma paracetamol concentration was significantly delayed in the groups given fentanyl 50 and 100 microg and diamorphine 5 mg, compared to the groups given bupivacaine alone, and peak concentration was significantly reduced in the group given diamorphine 5 mg. It is concluded that epidural fentanyl 50 and 100 mg and epidural diamorphine 5 mg delay gastric emptying. The addition of 2.5 mg diamorphine has no significant effect.

Journal Article↗
PubMed1993

Factors affecting the maternal-fetal distribution of pethidine and bupivacaine in the rabbit.

Twenty pregnant New Zealand white rabbits (mean body weight 4.6 kg) within 3 days of term were anaesthetized and given an intravenous infusion of bupivacaine 1.25 mg/ml with pethidine 1.25 mg/ml at a rate of 12 ml/h for 20 min, 6 ml/h for 60 min and 3 ml/h thereafter. In 10 of the does the solution also contained adrenaline 1.25 microg/ml. Up to 8 fetuses were removed at 15 min intervals from the start of the infusion and umbilical vein pH was measured, together with bupivacaine and pethidine concentrations, in fetal plasma, fetal brain and maternal plasma sampled synchronously. Mean umbilical vein pH fell with time with no significant difference between the groups. Maternal plasma concentrations of both drugs did not alter significantly during the experiment. Maternal clearance of bupivacaine was 85.6 ml/min and of pethidine was 249 ml/min. Despite the three-fold higher maternal plasma concentrations of bupivacaine, concentrations of pethidine in fetal plasma and brain were consistently higher than those of bupivacaine. Fetal plasma pethidine concentrations rose 0.276 microg x ml(-1)h(-1) and bupivacaine concentrations rose 0.184 microg x ml(-1)h(-1). The mean (+/-SD) maximum fetal: maternal plasma ratio for bupivacaine was 0.361+/-0.127 and for pethidine 1.78+/-0.81. The fetal brain:plasma ratio of pethidine was consistently higher than that of bupivacaine and did not change significantly with time, whereas that of bupivacaine fell significantly (P<0.05). Concentrations of bupivacaine and pethidine in fetal and maternal brain were consistently higher with adrenaline, although adrenaline had no significant effect on the concentrations in this or any compartment.

Journal Article↗
PubMed1993

Is opioid loading necessary before opioid/local anaesthetic epidural infusion? A randomized double-blind study in labour.

The effects of two different epidural loading doses administered before starting an opioid/low dose local anaesthetic infusion were examined in a randomized double-blind study during labour. Forty mothers were given either 10 ml 0.25% plain bupivacaine or 10 ml 0.125% plain bupivacaine containing 5 mcg of sufentanil followed in all cases by epidural infusion of 0.08% plain bupivacaine containing 0.2 mcg/ml of sufentanil, which was continued into the second stage. The quality of analgesia did not differ significantly between the groups in either the first or the second stage of labour: in each group 75% of women required 0 or 1 top-up during labour and verbal numerical pain scores were similar. Over 80% of women in each group reported a pain free second stage of labour. There were no differences in the mode of delivery between the groups with 60% of women in each group having a spontaneous vaginal delivery. The proportion of women with motor block increased with the duration of the epidural infusion, with no difference between the groups. There was no difference in the degree of maternal satisfaction assessed 24 hours after delivery, with 80% of women in each group awarding the maximum verbal numerical score for their satisfaction with epidural analgesia. The incidence of maternal side effects (nausea, vomiting, drowsiness and pruritus) was similar in the 2 groups as was neonatal outcome, assessed by Apgar and neurological and adaptive capacity scores and umbilical artery and vein pH. We conclude that opioid loading before opioid/low-dose bupivacaine epidural infusions is unnecessary.

Journal Article↗
PubMed1993

Histamine release by morphine and diamorphine in man.

Intravenous morphine and diamorphine are routinely used for postoperative analgesia but the relative histamine releasing abilities of these drugs have not been compared in man. Thirty-eight patients were randomly allocated to receive morphine (0.16 mg.kg-1) or diamorphine (0.08 mg.kg-1) after abdominal surgery. Blood samples for histamine were taken before, and at timed intervals after, opioid administration and analysed by an isotopic radioenzymatic technique. Haemodynamic parameters and pain scores were recorded before and after analgesic administration, and a series of eight basophil histamine release studies was also performed. Significant histamine release (plasma concentration > 2 ng.ml-1 or rise of > 700% baseline) occurred in 23.5% of the morphine group and 21.1% of the diamorphine group. Histamine was released earlier in those receiving diamorphine, but no significant change in haemodynamic parameters occurred, and no histamine release was demonstrated in the basophil histamine release studies. These findings suggest that morphine and diamorphine release histamine from mast cells rather than basophils.

Adolescent↗
PubMed1993

Can pre-emptive lumbar epidural blockade reduce postoperative pain following lower abdominal surgery?

In a double-blind study, 36 patients who received a standard general anaesthetic for abdominal hysterectomy or myomectomy, received either 15 ml of bupivacaine 0.5% with adrenaline by lumbar epidural injection 15 min before surgery (group A) or the same dose at the end of surgery but before waking (group B). Pain was assessed for 24 h by cumulative morphine dose (self-administered by patient-controlled analgesia), visual analogue scale and verbal rating score. Patients were included for analysis if they were pain free on waking and for at least 2 h after. There was no significant difference (p > 0.05) between the two groups in morphine dose, visual analogue scale or verbal rating score at 6 and 24 h after waking. As expected, there was a significant difference in the mean time of first use of patient-controlled analgesia (4.26 h in group A vs 5.06 h in group B, p < 0.05). Consequently, we compared the morphine dose, visual analogue scale and verbal rating score at 23 h in group A with those at 24 h in group B. Again there were no significant differences between the two groups. We were unable to demonstrate that epidural blockade had a significantly better effect on postoperative pain when administered before, rather than after, surgery.

Adult↗
PubMed1993

Epidural infusions for nulliparous women in labour. A randomised double-blind comparison of fentanyl/bupivacaine and sufentanil/bupivacaine.

Sixty nulliparous women received epidural infusions in labour of 0.0625% bupivacaine containing either 2.5 micrograms.ml-1 of fentanyl or 0.25 micrograms.ml-1 of sufentanil, each starting at 12 ml.h-1. The duration of each stage of labour did not differ significantly between the groups nor did the mode of delivery. The quality of analgesia in the first and second stages of labour and at delivery was similar in the two groups and there were no significant differences in the bupivacaine dose requirements. In the fentanyl group, 90% of women required one or no top-ups compared with 87% in the sufentanil group. Five women in the fentanyl group and four in the sufentanil group developed motor blockade, limited to movement of the hip only. Six women (20%) in each group reported pruritus. There were no significant differences in Apgar scores, umbilical cord blood pH levels or neurologic and adaptive capacity scores at 2 or 24 h. Satisfaction with first and second stage analgesia was high with no differences between the groups. There were no significant differences in the incidence of postnatal symptoms with 52% of women reporting perineal pain and 45% localised backache.

Adult↗
PubMed1993

A comparison of epidural diamorphine with intravenous patient-controlled analgesia using the Baxter infusor following caesarean section.

In a randomised study of analgesia following Caesarean section, we compared the efficacy and side effects of on-demand epidural diamorphine 2.5 mg with intravenous patient-controlled analgesia using diamorphine from the Baxter infusor system. Pain scores fell more rapidly in the epidural group, but by the fourth hour, and thereafter, both techniques had a similar analgesic effect. The patient-controlled analgesia group used significantly more diamorphine (p < 0.001), median 62 mg (range 18-120 mg) compared to the epidural group, median 10 mg (range 2.5-20 mg), over a significantly longer time period (p < 0.001), median 54.25 h (range 38-68 h) compared to the epidural group, median 40.75 h (range 6-70 h). The frequency and severity of nausea, vomiting and pruritus were similar in the two groups, however, the patient-controlled analgesia group were more sedated during the first postoperative day. This reached statistical significance (p < 0.05) between 9-24 h. Overall satisfaction scores (0-100) were high, but the patient-controlled analgesia group scored significantly higher: mean 85.5 (SD 12.2) compared to mean 77.0 (SD 11.7) in the epidural group.

Adult↗
PubMed1992

Plasma total and free concentrations of bupivacaine and lignocaine in mother and fetus following epidural administration, singly or together.

Forty six women undergoing elective caesarean section under epidural blockade were given 20 ml of either bupivacaine 0.5% plain (B) or with adrenaline 5 microg/ml (B + A), lignocaine 2% with adrenaline 5 microg/ml (L + A) or a mixture of equal parts of L + A and B + A (BLA). Further doses of the same solution were given at 20 min if necessary. Free and total plasma concentrations of the local anaesthetics were measured in maternal venous plasma 10, 20, 40, 60 and 120 min after the main dose and in umbilical venous plasma at delivery. Protein binding of both drugs was significantly higher in mother than baby. Lignocaine did not affect bupivacaine binding but lignocaine binding was higher in group BLA than L + A. Otherwise the presence of one drug had little effect on the disposition of the other drug in mother or baby. No plasma concentrations were considered toxic. Adrenaline did not reduce maternal C(max) of free bupivacaine and appeared to be associated with increased fetal uptake of bupivacaine.

Journal Article↗
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↗