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Biomedical subjects

C D Gomersall

Publications and source records attributed to C D Gomersall.

At least 19 recordsLinked to original sources
PubMed1998

A comparison of the Hamamatsu NIRO 500 and the INVOS 3100 near-infrared spectrophotometers.

Near-infrared spectroscopy is a technique used for non-invasive measurement of cerebral oxygenation and a number of commercial devices are currently available for use. We compared measurements of cerebral oxygenation made with two near-infrared spectrophotometers--the Somanetics Invos 3100 cerebral oximeter and the Hamamatsu NIRO-500 near-infrared spectrophotometer. Hypoxia was induced in six healthy male volunteers with and without occlusion of scalp blood flow. Oxygen saturation, end-tidal carbon dioxide tension, regional cerebral oxygen saturation, change in regional cerebral oxyhaemoglobin concentration and change in regional cerebral total haemoglobin concentration were measured. The INVOS 3100 displays cerebral oxygen saturation directly. The NIRO-500 displays change in total haemoglobin concentration and oxyhaemoglobin concentration, and the cerebral oxygen saturation was calculated offline. Statistical analysis disproved the assumption that the INVOS 3100 and the NIRO-500 were measuring the same changes in cerebral oxygenation. Neither machine can be confirmed for reliability against a gold standard and operational difficulties mean that neither can be recommended for routine clinical use.

Brain↗
PubMed1997

Intermittent bolus dosing of ceftazidime in critically ill patients.

Ceftazidime is frequently used in critically ill patients, particularly for the treatment of Pseudomonas aeruginosa infections. The recommended dosing regimen is based on pharmacokinetic data obtained in healthy volunteers and may not be appropriate in the critically ill. We administered ceftazidime in the maximum recommended dose (2 g i.v. every 8 h) to ten critically ill patients with normal plasma creatinine. Eighteen arterial blood samples were taken from each patient over the first 8 h for measurement of ceftazidime concentrations and subsequent compartmental pharmacokinetic analysis. An additional trough sample was taken from each patient on day 3. Although mean pharmacokinetic variables did not differ from previously reported data in normal volunteers there was wide variability in plasma drug concentrations. Three of our patients had plasma ceftazidime concentrations less than the MIC for P. aeruginosa (8 mg/L) and nine had concentrations less than 5 x MIC, which has been recommended to ensure efficacy. On day 3 trough ceftazidime concentrations were less than the MIC in four out of the seven patients in whom measurements were made and less than 5 x MIC in the remaining three. There was no clinical predictor of which patients would have low plasma concentrations. Our results show that plasma concentrations of ceftazidime are very variable when the recommended intermittent bolus dosing regimen is used and may result in inadequate plasma concentrations of drug in critical infections. This may result in treatment failure and the emergence of antibiotic resistance. A loading dose followed by continuous infusion should overcome these problems but this awaits in-vivo evaluation.

Adult↗
PubMed1997

Oxygen delivery, oxygen consumption, and gastric intramucosal pH are not improved by a computer-controlled, closed-loop, vecuronium infusion in severe sepsis and septic shock.

OBJECTIVE: To investigate the influence of the neuromuscular blocking agent vecuronium on oxygen delivery (DO2), oxygen consumption (VO2), oxygen extraction ratio, and gastric intramucosal pH in heavily sedated patients with severe sepsis or septic shock. DESIGN: Prospective, randomized, placebo-controlled, cross-over trial. SETTING: University hospital intensive care unit. PATIENTS: Eighteen mechanically ventilated patients with severe sepsis or septic shock. INTERVENTIONS: All patients were heavily sedated. After baseline measurement, a computer-controlled, closed-loop infusion of either vecuronium or saline was initiated and further measurements were made at 40 and 60 mins. The procedure was repeated with the alternative agent after return of neuromuscular function. MEASUREMENTS AND MAIN RESULTS: DO2, VO2, intramucosal pH were monitored using pulmonary artery catheters, a gas exchange monitor, and gastric tonometers. Changes from baseline were compared (paired t-test, p = .05). The vecuronium closed-loop infusion achieved T1 between 5% and 15% at 40 mins. There was a significant difference in the changes from baseline for static respiratory compliance in the vecuronium closed-loop infusion group compared with the saline closed-loop infusion group. There was no significant difference in the change from baseline for systemic or pulmonary vascular resistance, DO2, VO2, oxygen extraction ratio, or intramucosal pH. CONCLUSIONS: In these patients, vecuronium infusion achieved the targeted level of paralysis and improved respiratory compliance but did not alter intramucosal pH, VO2, DO2, or oxygen extraction ratios. With deep sedation, neuromuscular blockade in severe sepsis/septic shock does not significantly influence oxygen flux and should be abandoned as a routine method of improving tissue oxygenation in these patients.

Adult↗
PubMed1997

Delayed upper airway obstruction. A life-threatening complication of Dettol poisoning.

Dettol liquid is a commonly used household disinfectant and although it is labelled nonpoisonous, serious respiratory complications have been reported in up to 8% of cases of Dettol ingestion. We report a case in which the delayed onset of upper airway obstruction was treated with emergency awake, fibreoptic guided nasotracheal intubation. Based on information available in published cases and on our own experience, we suggest that patients who have ingested large volumes of Dettol, have a history of vomiting or unprotected lavage, or have evidence of ongoing oropharyngeal inflammation, are at high risk of this complication. They should be closely observed for at least 48 h after ingestion and the facilities and staff required for emergency airway management should be immediately available.

Aged↗
PubMed1997

Gastric tonometry and prediction of outcome in the critically ill. Arterial to intramucosal pH gradient and carbon dioxide gradient.

Splanchnic ischaemia is thought to be of central importance in the development of multi-organ failure and hence death in critically ill patients. It has been suggested that the arterial to gastric intramucosal pH gradient and the difference in partial pressure of carbon dioxide between gastric mucosa and arterial blood are more sensitive markers of splanchnic ischaemia than gastric intramucosal pH itself and thus should be predictors of mortality in the critically ill. We studied 62 critically ill patients within 6 h of admission to the intensive care unit and found no significant difference at 0, 12 or 24 h after admission to the study in either the arterial to gastric intramucosal pH gradient or the difference in partial pressure of carbon dioxide between gastric mucosa and arterial blood between survivors and nonsurvivors. We conclude that in contrast to gastric intramucosal pH neither the arterial to gastric intramucosal pH gradient nor the difference in partial pressure of carbon dioxide between gastric mucosa and arterial blood distinguish survivors from nonsurvivors.

Adult↗
PubMed1997

Gastric intramucosal pH and blood lactate in severe sepsis.

We prospectively investigated the effect of conventional resuscitation on gastric intramucosal pH and lactate over 5 days in a group of patients with newly diagnosed severe sepsis. Lactate and gastric intramucosal pH were measured on entry into the study, as soon as resuscitation end points were met, eight hourly for 48 h and daily for 5 days. Sixteen of 18 patients had a low gastric intramucosal pH (mean (SD) 7.17 (0.12)) at the time of diagnosis of severe sepsis. At no time did gastric intramucosal pH or lactate distinguish between shocked and nonshocked patients. Lactate distinguished survivors from nonsurvivors over time (p = 0.02). Gastric intramucosal pH did not distinguish survivors from nonsurvivors over time (p = 0.72). At 48 h lactate was lower in survivors (p < 0.01) and gastric intramucosal pH higher in survivors (p < 0.05). Receiver operating characteristic curves at this time indicate that lactate is a better predictor of survival. It is likely, based on the inability of gastric intramucosal pH to distinguish survivors from nonsurvivors until 48 h, that it is not possible to use this measurement to guide resuscitation in patients who are severely ill and who have gastric intramucosal acidosis.

Adult↗
PubMed1996

Comparison of intrathoracic and intra-abdominal measurements of central venous pressure.

BACKGROUND: Complications can arise from standard intrathoracic central venous pressure (CVP) measurements in critically ill, mechanically ventilated patients. We have assessed the feasibility of catheterisation by the femoral route to measure CVP in the abdomen (ACVP). We compared measurements by the standard jugular or subclavian route (TCVP) with simultaneous ACVP measurements by the femoral route. METHODS: Between June, 1994 and May, 1995, we recruited 20 critically ill adult patients with various disorders; all patients already had a TCVP line in situ. We placed a femoral catheter in the inferior vena cava close to the right atrium under electrocardiographic guidance. The catheter position was confirmed (and corrected if necessary) by chest radiography. CVP was measured from both sites hourly for 6 h. Positive end-expiratory pressure, mean airway pressure, and intra-abdominal pressure were recorded simultaneously. FINDINGS: One patient was excluded because radiography showed that the catheter position was incorrect. For 133 paired measurements of ACVP and TCVP in the remaining 19 patients, the mean difference was 0.45 mm Hg (SD 0.89: 95% Cl 0.30-0.60); the limits of agreement were -1.33 to 2.23 mm Hg (-1.63 to 2.53). We found a small tendency for the difference between ACVP and TCVP to increase as positive end-expiratory pressure and mean airway pressure increased; the difference was statistically, but not clinically, significant. INTERPRETATION: Our study showed that for clinical purposes CVP can be measured by a femoral catheter placed in the abdominal inferior vena cava near the right atrium. This approach can replace standard TCVP measurements in critically ill, mechanically ventilated patients.

Abdomen↗
PubMed1996

Extradural anaesthesia for caesarean section in a patient with moyamoya disease.

We report a case of moyamoya disease in a patient presenting for Caesarean section at 37 weeks' gestation. Extradural anaesthesia was administered using 0.5% bupivacaine and pethidine 25 mg. A stable haemodynamic state was produced using left lateral uterine displacement, i.v. crystalloids and an i.v. infusion of ephedrine. The patient suffered no neurological deficit and there was no significant intraoperative decrease in cerebral oxygenation measured by near infrared spectroscopy.

Adult↗
PubMed1996

Upper airway obstruction caused by acquired inhibitor to factor VIII.

Bleeding caused by inhibitors to factor VIII is a rare medical emergency requiring immediate specialist investigation and management. Urgent initiation of therapy with high dose factor VIII concentrates may be life saving. Successful management of acute upper airway obstruction from uncontrolled haemorrhage into the oropharyngeal tissues should be achieved with fibreoptic guided nasotracheal intubation.

Adult↗
PubMed1996

Gastric tonometry.

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Gastric Mucosa↗