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Biomedical subjects

T A Thomas

Publications and source records attributed to T A Thomas.

At least 19 recordsLinked to original sources
PubMed1997

The influence of timing of ketorolac administration on post-operative analgesic requirements following total abdominal hysterectomy.

One hundred and thirty-seven patients were studied to assess whether the timing of a dose of ketorolac affected cumulative morphine requirements during the first 12 post-operative hours. Pain, sedation and nausea scores, respiratory rate and degree of operative blood loss were also recorded. Thirty-six patients (group A) were given placebo injections pre- and intra-operatively. Thirty-one patients (group B) received placebo pre-operatively and ketorolac 30 mg intra-operatively. Thirty-six patients (group C) received ketorolac 10 mg pre-operatively and ketorolac 20 mg intra-operatively and thirty-four patients (group D) were given ketorolac 30 mg pre-operatively and placebo intra-operatively. Post-operative analgesia was with intravenous (i.v.) morphine administered using a patient controlled analgesia (PCA) device. Analysis of variance revealed a significant difference in morphine consumption at 1, 2, 4, 8 and 12 h postoperatively (P < 0.05) between group A (no ketorolac) and groups B, C and D (ketorolac). However, there were no significant differences between groups B, C and D during the study period. Thus, the timing of ketorolac administration made no difference to overall morphine consumption. Pain, nausea, sedation and respiratory rate scores were similar in all four groups. There was a significantly greater blood loss in patients receiving ketorolac (groups B, C and D) compared with those receiving placebo alone (group A).

Adult↗
PubMed1997

Simulation of resistance forces acting on surgical needles.

High precision in the manual control of needles and biopsy probes in medical treatment requires high skill and dexterity levels. In anaesthesia, force sensation is an important feedback mechanism, and the practitioner needs to refresh or develop skills to improve on the interpretation of needle progress towards the target site. This paper describes an experimental tactile force simulator for uniaxial needle action for which the force resisting progress of the needle is derived from measured data. As an example, the approach taken to develop the simulation of the insertion of epidural needles is described. Adaptation to other procedures would be possible by adopting new reference models based on appropriate measured force data.

Animals↗
PubMed1995

Epidural infusions of bupivacaine and diamorphine in labour.

Three different concentrations of bupivacaine, 0.125%, 0.062% and 0.031%, all with diamorphine 0.0025%, were given as an epidural infusion at 10 ml.h-1 to 63 mothers in labour. When the three infusions were compared, significant differences were found in maternal requirements for top-ups and the degree of motor block, but there were no differences in the pain scores. The reduced motor block was not associated with a reduction in the instrumental delivery rate.

Adult↗
PubMed1994

Overpressure isoflurane at caesarean section: a study of arterial isoflurane concentrations.

In this study we have measured arterial concentrations of isoflurane obtained during Caesarean section in two groups of patients. Patients in group 1 received 1% isoflurane throughout operation, whilst those in group 2 received 2% isoflurane for the first 5 min, 1.5% for the next 5 min and 0.8% thereafter. We found that arterial isoflurane concentrations were significantly greater in group 2 than in group 1 (ANOVA, P < 0.05). Isoflurane concentrations greater than 30 micrograms ml-1 were achieved rapidly in most patients in both groups, but there was a large scatter of results. The isoflurane concentration at which awareness or recall may occur is not known, but an "overpressure" technique as described for patients in group 2 may result in fewer patients being at risk of awareness.

Adolescent↗
PubMed1993

Comparison of automatic oscillometric arterial pressure measurement with conventional auscultatory measurement in the labour ward.

We have compared two non-invasive methods of arterial pressure (AP) measurement used in labour wards: an automatic oscillometric measurement obtained by Dinamap 1846, and a conventional auscultatory measurement obtained by midwives. A total of 369 AP measurements were recorded, involving 28 normotensive and hypertensive pregnant women during labour, with or without extradural analgesia. Compared with the midwife group, the Dinamap group had a greater systolic AP, by 2.7 mm Hg (P < 0.01) and smaller diastolic AP, by 9.8 mm Hg (P < 0.01). The correlations between the two methods were highly significant, but the limits of agreement were relatively wide for both systolic and diastolic AP measurements. We conclude that a clinically important difference exists in diastolic AP measurements. Dinamap diastolic AP must be corrected using a regression equation, or simply by adding 10 mm Hg, before being compared with the available normal and hypertensive AP values.

Adult↗
PubMed1993

Isoflurane in labour.

A comparison of the analgesic efficacy of Entonox (50% nitrous oxide in oxygen) and Entonox with 0.2% isoflurane was made in 18 consenting mothers during the first stage of labour. The inhalational gases were self-administered during contractions over a 3 h study period using a standard Entonox demand valve and breathing system. Isoflurane 0.2% was added from an Ohmeda Isotec drawover vaporizer and the inspired concentration of isoflurane was analysed continuously using a Datex Ultima analyser. Linear analogue scores for pain were significantly lower (p < 0.001) during the Entonox-isoflurane administration compared with Entonox alone. Drowsiness was not a clinical problem and there was a high acceptance rate for Entonox-isoflurane inhalational analgesia during labour.

Adolescent↗
PubMed1992

Spinal anaesthesia for caesarean section: comparison of 22-gauge and 25-gauge Whitacre needles with 26-gauge Quincke needles.

We have studied 150 women undergoing elective Caesarean section under spinal anaesthesia. They were allocated randomly to have a 22-gauge Whitacre, a 25-gauge Whitacre or a 26-gauge Quincke needle inserted into the lumbar subarachnoid space. The groups were compared for ease of insertion, number of attempted needle insertions before identification of cerebrospinal fluid, quality of subsequent analgesia and incidence of postoperative complications. There were differences between groups, but they did not reach statistical significance. Postdural puncture headache (PDPH) was experienced by one mother in the 22-gauge Whitacre group, none in the 25-gauge Whitacre group and five in the 26-gauge Quincke group. Five of the six PDPH occurred after a single successful needle insertion. Seven of the 15 mothers in whom more than two needle insertions were made experienced backache, compared with 12 of the 129 receiving two or less (P < 0.001). We conclude that the use of 22- and 25-gauge Whitacre needles in elective Caesarean section patients is associated with a low incidence of PDPH and that postoperative backache is more likely when more than two attempts are made to insert a spinal needle.

Adolescent↗
PubMed1991

Epidural infusion of diamorphine with bupivacaine in labour. A comparison with fentanyl and bupivacaine.

We have compared the analgesic effects of three epidural infusions in a randomised, double-blind study of 61 mothers in labour. An initial dose of bupivacaine 0.5% 8 ml was followed by either bupivacaine 0.125%, bupivacaine 0.125% with diamorphine 0.0025% or bupivacaine 0.125% with fentanyl 0.0002%. All infusions were run at a rate of 7.5 ml/hour. Analgesia was significantly better in both the groups receiving opioids. Diamorphine was shown to be the more effective supplement to bupivacaine. The 5% incidence of pruritus in the opioid groups was less than that reported by earlier authors.

Analgesia, Epidural↗
PubMed1991

Epidural bupivacaine dilution for labour. A comparison of three concentrations infused with a fixed dose of fentanyl.

We have compared the effects of three epidural infusions in a randomised, double-blind study of 56 primigravid mothers in labour. An initial dose of bupivacaine 0.5% 8 ml was followed by infusion of either bupivacaine 0.125%, 0.062% or 0.031%. All solutions contained fentanyl 0.0002% and were run at 7.5 ml/hour. Women receiving the most dilute solution had significantly less analgesia (p less than 0.001) for the first 4 hours of the study, but pain scores were then similar for the three groups. No obvious benefit was gained by using very dilute bupivacaine.

Adult↗
PubMed1988

Posture and post-spinal headache. A controlled trial in 80 obstetric patients.

Eighty obstetric patients receiving subarachnoid anaesthesia for second and third stage procedures, excluding Caesarean section, were studied. They were randomly allocated postpartum to either 24 h bed rest or early (6 h post spinal) mobilization. Patients were followed up at 48 h post-partum and the incidence and severity of post-spinal headache noted. There was a significantly greater incidence of severe spinal headaches in the "bed-rest" group and three patients in this group required blood patch treatment for their headache. Early mobilization is, therefore, the recommended management after spinal anaesthesia for these types of obstetric procedure.

Adult↗
PubMed1988

Maternal inspired oxygen concentration and neonatal status for caesarean section under general anaesthesia. Comparison of effects of 33% or 50% oxygen in nitrous oxide.

The relationship between maternal FIO2 and umbilical venous PO2, PCO2, pH and neonatal Apgar and TSR (time to sustained respiration) scores was studied in 35 patients undergoing Caesarean section under general anaesthesia. Patients were allocated randomly to breathe an FIO2 of either 0.5 or 0.33. Umbilical venous blood was collected at the time of delivery, and TSR and 1- and 5-min Apgar scores recorded. Mean values for umbilical venous blood were: PO2 3.9 kPa and 3.7 kPa; PCO2 6.2 kPa and 6.2 kPa; pH 7.30 and 7.31 (50% and 33% groups, respectively (P greater than 0.05]. No differences were found between groups for 1- or 5-min Apgar scores or TSR values. It is concluded that no difference in fetal outcome or acid-base status can be detected when maternal FIO2 is decreased from 0.5 to 0.33, and that the use of 33% oxygen in 66% nitrous oxide appears to be safe for neonates who have not suffered fetal distress before delivery.

Anesthesia, General↗
PubMed1986

Prescribing for labour.

Prostaglandins, particularly PGE2 vaginally, can be valuable for cervical ripening or induction of labour in some women. Ease of use must not be allowed to result in unjustified intervention. Amniotomy followed by oxytocin infusion are the methods of choice for induction of labour. Careful monitoring of the maternal and fetal condition are vital, especially if an epidural block is in place. Augmentation of labour is only appropriate for inefficient primigravid labour. Failure to progress in a multiparous woman is more likely to be due to obstruction. Low residue, easily digested foodstuffs are not necessarily contraindicated during normal labour. When properly used, Entonox can provide analgesia equivalent to 75-100 mg pethidine. Sodium citrate is the antacid of choice during labour and should be combined with an H2-receptor blocking agent for caesarean section, or other procedure involving anaesthesia. The routine injection of Syntometrine at delivery of the anterior shoulder to prevent PPH is widespread in the UK but has not been properly tested. Oxytocics are invaluable in the treatment of PPH.

Anesthesia, General↗
PubMed1984

A method for producing normocarbia during general anaesthesia for caesarean section.

Twenty-six patients were anaesthetised for Caesarean section using the Bain anaesthetic system for intermittent positive pressure ventilation. There was an inverse relationship between maximum end tidal carbon dioxide tension and the fresh gas flow (FGF) to the system. A significant difference existed between the patients receiving 80 ml/kg/min FGF and those receiving 120 ml/kg/min. Estimated carbon dioxide levels in the pregnant term patient were higher at each FGF rate than the levels reported in non-pregnant patients by other workers. In order to maintain maternal arterial carbon dioxide tension at or close to the normally quoted term value of 4.1-4.4 kPa, when using positive pressure ventilation with a Bain system, a fresh gas flow rate of at least 120 ml/kg body weight/minute is required.

Anesthesia, General↗
PubMed1983

An investigation into opioid systems in the pregnant rat.

The role of opioid peptides during pregnancy and parturition has not been defined. They may function as natural analgesics during parturition. Pain thresholds were tested during pregnancy but, in contrast with a previous study, were found not to change. Plasma Beta-endorphin-like-immunoreactivity (B-ELI) was measured and towards the end of pregnancy a significant increase was recorded. Peptide levels returned to the pre-gestational concentration just prior to parturition. Pituitary B-ELI was also measured and was only significantly raised on the day before expected parturition. These changes add to the evidence that opioid peptides have a physiological function during pregnancy and parturition.

Animals↗