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W D Morton

Publications and source records attributed to W D Morton.

5 recordsLinked to original sources
PubMed1997

Serum bupivacaine concentrations during continuous extrapleural infusion.

PURPOSE: To determine the rate of increase in serum bupivacaine concentration during continuous extrapleural infusion. METHODS: After thoracotomy for lobectomy under general anaesthesia, nine patients had an extrapleural catheter inserted, before chest closure, in a costovertebral gutter constructed surgically by lifting the parietal pleural. Bupivacaine 0.5% with epinephrine 1:200.000 was injected through the catheter as 0.3 ml.kg-1 bolus followed by 0.1 ml.kg-1.hr-1 for five days. Serum bupivacaine (free and total), albumin, alpha-1 acid glycoprotein concentrations were measured 15 min after injection and at 24 hr intervals for five days. Bupivacaine concentrations were determined by column liquid chromatography using solid phase extraction. Serum alpha-1 acid glycoprotein concentration was determined by nephelometry on QM 300 protein analyzer. Serum albumin concentration was determined by bromocresol green dye binding procedure on Hitachi 717 Autoanalyzer. RESULTS: A continuous elevation in total serum bupivacaine was observed, with an average value of 0.75 microgram.ml-1 on day 1 to 2.77 micrograms.ml-1 on day 4 (P < 0.05). There was no increase in postoperative free serum bupivacaine concentration; average value of 177 pcg.ml-1 on day 1 and 249 pcg.ml-1 on day 4 (P = 0.92). Postoperative serum alpha-1 acid glycoprotein concentration showed a steady rise with an average value of 0.94 microgram.ml-1 on day 1 and 1.47 micrograms.ml-1 on day 4 (P < 0.05). No change was observed in post-operative serum albumin with an average value of 31.4 g.l-1 on day 1 and 31.3 g.l-1 on day 4. CONCLUSION: Continuous extrapleural infusion of bupivacaine over five days after thoracotomy is associated with a steady increase in total serum bupivacaine concentration and no elevation in free serum bupivacaine concentration.

Adult↗
PubMed1988

The non-invasive determination of cardiac output in children: a three-breath technique.

In this study, the cardiac output of 11 children (5 days to 18 yr of age) was measured following cardiopulmonary bypass. Standard dye dilution cardiac outputs and an indirect Fick-CO2 technique were simultaneously determined. A rebreathing maneuver is described to estimate the oxygenated mixed venous PCO2 (PvCO2). This estimate of PvCO2 was combined with the end tidal PCO2 and CO2 production to give a non-invasive Fick estimate of the cardiac output. Non-invasive cardiac outputs correlated well with those measured by dye-dilution (r2 = 0.94) over a range of cardiac outputs from 490-7280 ml/min. All non-invasive determinations were within 15% of the line of identity, and within 22% of averaged replicate dye-dilution values. Our results agree with previous comparisons of indirect Fick-CO2 methods with invasive determinations of cardiac output. These data suggest that the indirect Fick-CO2 technique offers a rapid, non-invasive alternative to invasive monitoring of cardiac output.

Adolescent↗
PubMed1987

The effect of pancuronium on the solubility of aqueous thiopentone.

In this study we identified the precipitate formed when pancuronium bromide (pH 3.9) and sodium thiopentone (pH 10.6) are combined in vitro. A precipitate formed when sufficient pancuronium was added to thiopentone to decrease the pH below 9.25. The precipitate was isolated, redissolved in alkaline solution and identified as thiopentone using ultraviolet spectrophotometry. Pancuronium was soluble in water in the pH range of 2.0 to 12.0, whereas thiopentone was soluble in water only at a pH greater than 9.90. We conclude that thiopentone precipitates when combined with pancuronium because of a pH-dependent decrease in the solubility of thiopentone, rather than a chemical interaction.

Anesthesia↗
PubMed1979

McMaster revisited.

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Education, Medical, Graduate↗