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Biomedical subjects

R S Laishley

Publications and source records attributed to R S Laishley.

14 recordsLinked to original sources

Tension pneumothorax and pulse oximetry.

A case is described of spontaneous tension pneumothorax occurring during preparation for thoracic surgery. The earliest indication of this was unexplained haemoglobin desaturation as detected by pulse oximetry. This case report provides another example of the early warning potential of pulse oximetry.

Humans↗

Anaesthesia for simultaneous caesarean section and clipping of intracerebral aneurysm.

A 38-yr-old woman who was 35 weeks pregnant presented with a subarachnoid haemorrhage, secondary to a ruptured anterior communicating artery aneurysm. Following initial recovery, she subsequently underwent simultaneous elective Caesarean section and clipping of the aneurysm. The anaesthetic management of the case is described and discussed.

Adult↗

Effect of adrenaline on placental transfer of bupivacaine in the perfused in situ rabbit placenta.

Following general anaesthesia, each of 18 pregnant rabbits received an i.v. infusion, at a declining rate, of 0.125% bupivacaine, either plain solution followed by adrenaline (1.25 micrograms ml-1)-containing solution (n = 10) or vice versa (n = 8). All solutions contained antipyrine as an index of placental exchange. In each rabbit, a single fetal sac was opened, the umbilical vessels were cannulated and the placenta was perfused in situ with buffered Krebs solution containing Dextran. Bupivacaine and antipyrine concentrations were measured in effluent perfusate (fetal) and in maternal plasma sampled simultaneously. Mean maternal arterial pressure and mean placental perfusion pressure were not altered by adrenaline. Fetal:maternal concentration (F:M) ratios of antipyrine decreased significantly (P less than 0.05) during the second half of the experiment. In contrast, F:M ratios of bupivacaine were unchanged during the time course of the experiment and unaltered by the addition of adrenaline. It is concluded that neither adrenaline nor minor alterations in maternal placental flow affect placental transfer of bupivacaine.

Animals↗

Effect of adrenaline on the distribution of bupivacaine in the rabbit fetus.

Adrenaline may decrease uterine blood flow and influence transplacental distribution of bupivacaine. Sixteen pregnant rabbits received an i.v. infusion of 0.125% bupivacaine either plain (n = 8) or with adrenaline 1.25 microgram ml-1. At 15-min intervals following the start of the infusion, rabbit fetuses were removed serially and bupivacaine concentrations measured in maternal arterial plasma, fetal plasma and brain, amniotic fluid and placenta. The presence of adrenaline was associated with increased bupivacaine concentration in placenta; there was no other significant effect on fetal bupivacaine concentrations or ratios. Fetal:maternal plasma ratios increased (P less than 0.05), while fetal brain:fetal plasma ratios decreased (P less than 0.05) significantly with time.

Amniotic Fluid↗

Effect of adrenaline on extradural anaesthesia and plasma bupivacaine concentrations during caesarean section.

The effect of adrenaline on the efficacy of extradural block and plasma bupivacaine concentrations was investigated in women undergoing elective (n = 40) and emergency (n = 40) Caesarean section. Patients were randomly allocated within these two groups to receive 0.5% bupivacaine 20 ml either plain or with adrenaline 1 in 200,000, as a single fractionated extradural injection. The elective plain group needed significantly more supplementary analgesia compared with the other three groups (P less than 0.05). In the elective group, plasma bupivacaine concentrations were significantly lower in the subgroup receiving extradural adrenaline than in the plain subgroup. This effect was not observed when comparing only those who received bupivacaine 100 mg. In the emergency group, there were no significant differences in plasma bupivacaine concentrations between the plain and adrenaline subgroups. Maximum plasma concentrations correlated significantly (P less than 0.0001) with dose of bupivacaine (mg kg-1). It is concluded that extradural adrenaline does not usefully reduce systemic absorption of 0.5% bupivacaine, but may improve its efficacy in extradural anaesthesia for elective Caesarean section.

Adult↗

A single dose epidural technique for caesarean section. A comparison between 0.5% bupivacaine plain and 0.5% bupivacaine with adrenaline.

An epidural technique based on a fractionated injection through a Tuohy needle of 20 ml over 10 minutes, was investigated in 40 mothers who underwent elective caesarean section. Mothers were randomized to receive either 0.5% bupivacaine plain or 0.5% bupivacaine with adrenaline 1:200,000. After a 2-ml test dose, the remaining 18 ml was injected over 5 minutes. The use of adrenaline did not significantly alter the onset or duration, but improved the efficacy of the epidural block. Mean time to onset of adequate surgical anaesthesia was 20 minutes. Only 10 patients required more than the initial 100 mg of bupivacaine. Epidural anaesthesia was supplemented in eight patients with nitrous oxide and/or intravenous opioids.

Adult↗

Freeman-Sheldon syndrome: report of three cases and the anaesthetic implications.

The Freeman-Sheldon syndrome is a rare congenital myopathy and dysplasia. Fibrotic contractures of the facial muscles result in the characteristic "whistling face". Difficulties with intubation may be attributed in part to microstomia and micrognathia. In addition to other deformities, limb myopathy results in ulnar flexion contractures of the hand and equinovarus/valgus deformities of the feet. Intravenous access may be difficult because of limb deformities and thickened subcutaneous tissues. Limbs may be encased in plaster casts or splints limiting the available sites for venepuncture. Three case reports of children with Freeman-Sheldon syndrome are presented. The pathophysiology and anaesthetic problems encountered are discussed.

Anesthesia↗

Effects of dose and concentration of rectal methohexitone for induction of anaesthesia in children.

To investigate the effect of dose and concentration of rectal methohexitone for induction of anaesthesia, 60 children (ASA physical status 1 or 2) undergoing outpatient surgery were studied. Each child was randomly assigned to receive one of three rectal solutions (each containing atropine 0.02 mg X kg-1): Group A - ten per cent methohexitone, 25 mg X kg-1 (n = 20); Group B - ten per cent methohexitone, 15 mg X kg-1 (n = 20); or Group C - one per cent methohexitone, 15 mg X kg-1 (n = 20). After induction of anaesthesia, or a maximum period of 20 minutes following rectal administration of methohexitone, halothane, nitrous oxide, and oxygen were administered by mask. The time to induction of anaesthesia, complications, postanaesthetic recovery scores, and recovery time did not differ significantly among the three groups. The incidence of failed inductions did not differ significantly between Group A (zero per cent) and Group C (ten per cent) but both were significantly less than Group B (45 per cent) (p less than 0.05). Heart rate increased significantly between 10 and 30 minutes after rectal administration of methohexitone and atropine. The authors conclude that ten per cent rectal methohexitone 25 mg X kg-1 and one per cent rectal methohexitone 15 mg X kg-1 are equally effective for induction of anaesthesia in children and both are significantly more effective than ten per cent methohexitone 15 mg X kg-1.

Anesthesia, Rectal↗