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Biomedical subjects

J A Wildsmith

Publications and source records attributed to J A Wildsmith.

At least 73 records · Page 4Linked to original sources
PubMed1992

Surgical face masks are effective in reducing bacterial contamination caused by dispersal from the upper airway.

We have studied the effectiveness of surgical face masks in reducing bacterial contamination of a surface, produced by dispersal of organisms from the upper airway. Twenty-five volunteers were asked to speak at blood agar plates positioned in close proximity to the mouth, initially whilst not wearing a face mask and then wearing a surgical face mask over the mouth and nose. A fresh face mask almost completely abolished bacterial contamination of agar plates 30 cm from the mouth. After 15 min there was an increase in the level of contamination which was statistically insignificant.

Adult↗
PubMed1991

Transcranial Doppler monitoring during carotid endarterectomy.

Transcranial Doppler monitoring of the middle cerebral artery blood flow velocity was used as an adjunct to routine methods of cerebral monitoring in a prospective study of 30 consecutive patients undergoing carotid endarterectomy to investigate whether transcranial Doppler monitoring provided information influencing operative technique. Application of carotid clamps caused a significant fall in middle cerebral artery velocity and there was a linear relationship between middle cerebral artery velocity and internal carotid artery stump pressure. Assuming a stump pressure of less than 50 mmHg to be an indication for shunting, this would correspond to a systolic middle cerebral artery velocity of less than 42 cm/s and a mean velocity of less than 30 cm/s. Transcranial Doppler monitoring immediately identified problems with shunt function and demonstrated a higher frequency of intraoperative embolization than had been anticipated, particularly after shunt insertion and final restoration of flow. With revision of operative technique this phenomenon is rarely encountered now. Two of the 30 patients exhibited a minor neurological deficit on recovery of consciousness, and transcranial Doppler monitoring was able to identify the probable underlying cause in both cases. Unnecessary and potentially hazardous re-exploration was avoided. In the absence of transcranial Doppler monitoring the neurological deficit in one of the patients might have been much worse.

Blood Flow Velocity↗
PubMed1991

Comparison of extradural ropivacaine and bupivacaine.

Ropivacaine, a new long acting amide type local anaesthetic, was compared with bupivacaine in a randomized double-blind study. One hundred and ten patients undergoing extradural anaesthesia received a test dose of 3 ml of 1% lignocaine with adrenaline which was followed by 15 ml of one of five solutions: 0.5, 0.75 or 1.0% ropivacaine or 0.5 or 0.75% bupivacaine. There was little difference between the groups with respect to speed of onset or sensory block. The duration of analgesia was increased by increasing the concentration of both drugs, but this had minimal effect on onset time or extent of block. When the same concentration of each drug was administered, there were inconsistent differences in duration of sensory block, none of which was statistically significant. Increasing concentration of both drugs resulted in greater degree and longer duration of motor block. Ropivacaine produced a slower onset, shorter duration and less intense motor block than the same concentration of bupivacaine. The cardiovascular changes were similar in all groups.

Adolescent↗
PubMed1991

Effects of i.v. lignocaine on psychological performance and subjective state in healthy volunteers.

In order to assess the effects of different doses of lignocaine on performance, nine healthy volunteers aged 21-34 yr received i.v. infusions of saline, low and high dose lignocaine (mean plasma concentrations 0.92 and 1.78 micrograms ml-1, respectively) in a double-blind randomized order. The Digit-Symbol Substitution Test (DSST) and Visual Analogue Scales (VAS) were performed repeatedly and a battery of performance tests once. The median (lower, upper quartile) number of correct responses for the DSST during the infusion period was: placebo 69 (67, 77); low 74 (71, 80); high 66 (61, 75) (P less than 0.001, General Linear Models; all pairwise comparisons P less than 0.05). None of the measures in the full battery showed any significant changes. VAS showed that subjects felt more interested (P less than 0.05), drowsy (P less than 0.01), dizzy, tense, abnormal, drunk and muzzy (P less than 0.001) with lignocaine than with placebo. These results confirm that lignocaine can produce acute performance effects (both improvements and impairments). Subjects were clearly aware of the presence of lignocaine, suggesting that subjective reports may be a useful indicator of its CNS effects.

Adult↗
PubMed1991

Clinical evaluation of a spinal catheter technique in femoro-popliteal graft surgery.

The use of a 24-gauge catheter for continuous spinal anaesthesia was evaluated in 20 patients undergoing femoro-popliteal graft surgery for occlusive disease. The catheter was inserted through either a Tuohy or Quincke-tip needle and isobaric amethocaine used for the initial injection. In five patients identification of the subarachnoid space was not straightforward, but clear difficulty with catheter insertion was encountered in only one. The range of blocks seen was wider than expected, but it was adequate for surgery 15 minutes after injection in 16 of the 20 patients. In another three the injection of a small dose of hyperbaric bupivacaine produced the necessary extension of block. Two patients (10%) required a general anaesthetic, one because of grossly inadequate spread of solution, the other because the catheter kinked and prevented injection of a second dose after the start of surgery.

Aged↗
PubMed1991

Addition of fentanyl to prilocaine for intravenous regional anaesthesia.

Fifteen volunteers underwent intravenous regional anaesthesia on two occasions using 40 ml 0.5% prilocaine, to which had been added either 2 ml 0.9% saline or 0.1 mg fentanyl (resultant concentration 2.5 micrograms/ml). There was no difference in the rate of onset of blockade of cold sensation from an ethyl chloride spray, or to sharp and touch pinprick sensation in either group. There was an increase in the incidence of nausea after tourniquet release in the fentanyl group. It is concluded that the addition of fentanyl 2.5 micrograms/ml to prilocaine 0.5% confers no benefit in intravenous regional anaesthesia.

Adult↗
PubMed1991

Comparison of extradural and intravenous diamorphine as a supplement to extradural bupivacaine.

The influence of route of administration (extradural as compared with intravenous) of diamorphine 0.5 mg/hour as a supplement to extradural bupivacaine (0.125% at 15 ml/hour) was investigated in two groups of 20 patients who underwent major abdominal gynaecological surgery. Significantly more patients in the intravenous group withdrew because of inadequate analgesia (p less than 0.05). Those in the extradural group were significantly more drowsy throughout the study (p less than 0.01), but no major side effects were encountered.

Abdomen↗
PubMed1990

Effect of glucose concentration on the intrathecal spread of 0.5% bupivacaine.

We have studied the effects of intrathecal injection of 0.5% bupivacaine in solutions containing different concentrations of glucose (0.33%, 0.83% and 8%) in three groups of 10 patients. The mean maximum extent of sensory block was significantly higher with 8% glucose (T3.6) than with 0.83% glucose (T7.2) or 0.33% glucose (T9.5). Administration of solutions containing 0.33% glucose produced a greater variability in upper level of sensory block (11 dermatomes) than the two other concentrations (six dermatomes each). The rate of onset of sensory block to T12 was fastest with solutions containing 8% glucose. Complete motor block of the legs was produced in every patient.

Adult↗
PubMed1990

Alkalinisation of prilocaine for intravenous regional anaesthesia.

Ten volunteers underwent intravenous regional anaesthesia on two separate occasions using 40 ml prilocaine 0.5% to which was added 5 ml of either saline 0.9% or sodium bicarbonate 8.4%. Addition of sodium bicarbonate decreased the time of onset of loss of sharp touch and temperature sensations and of motor power. Time to full recovery of the arm was slower with the alkalinized solution and nine of the subjects preferred this block. The addition of sodium bicarbonate to prilocaine for intravenous regional anaesthesia may be clinically useful.

Adult↗
PubMed1989

Ten-year review of non-ruptured aortic aneurysms.

Between 1978 and 1987, 587 cases of abdominal aortic aneurysm were operated on in the Vascular Unit of the Royal Infirmary of Edinburgh. Over this ten-year period there was a dramatic increase in the number of patients treated. Rupture had occurred in 278 patients. Of the 309 patients with non-ruptured aneurysm 175 were asymptomatic, 84 were symptomatic and 50 were acutely symptomatic. Two hundred and fifty-nine patients underwent elective operation and the 50 acutely symptomatic patients were operated on as emergencies. The overall mortality for the non-ruptured series was 2.9 per cent. The mortality in patients undergoing elective surgery was 1.9 per cent (1.1 per cent in asymptomatic and 3.6 per cent in symptomatic patients) and 4.0 per cent for patients undergoing emergency surgery.

Adult↗