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Biomedical subjects

O Boyd

Publications and source records attributed to O Boyd.

At least 19 recordsLinked to original sources
PubMed1997

A cost analysis of a treatment policy of a deliberate perioperative increase in oxygen delivery in high risk surgical patients.

OBJECTIVE: To investigate the cost implications of a treatment policy of a deliberate perioperative increase of oxygen delivery in high risk surgical patients. DESIGN: A cost-effectiveness analysis comparing 'protocol' high risk surgical patients in whom oxygen delivery was specifically targeted towards 600 ml/min/m2 with 'control' patients. INTERVENTIONS: In a randomised, controlled clinical trial we previously demonstrated a significant reduction in mortality (5.7% vs 22.2%, p = 0.015) and morbidity (0.68 +/- 0.16 complications vs 1.35 +/- 0.20, p = 0.008) in 'protocol' high risk surgical patients in whom oxygen delivery was specifically targeted towards 600 ml/min per m2 compared with 'control' patients. This current study retrospectively analysed the medical care and National Health Service resource use of each patient in the trial. Departmental purchasing records and business managers were consulted to identify the unit cost of these resources, and thereby the cost of treating each patient was calculated. RESULTS: The median cost of treating a protocol patient was lower than for a control patient (6,525 pounds vs 7,784 pounds) and this reduction was due mainly to a decrease in the cost of treating postoperative complications (median 213 pounds vs 668 pounds). The cost of obtaining a survivor was 31% lower in the protocol group. CONCLUSION: Perioperative increase of oxygen delivery in high risk surgical patients not only improves survival, but also provides an actual and relative cost saving. This may have important implications for the management of these patients and the funding of intensive care.

Clinical Protocols↗
PubMed1996

Gastric tonometry.

Explore the source record for details and available documents.

Acid-Base Imbalance↗
PubMed1996

Enhancement of perioperative tissue perfusion as a therapeutic strategy for major surgery.

Multiple organ dysfunction syndrome (MODS) accounts for most surgical deaths which occur some days postoperatively. Current hypotheses concerning the pathophysiology of MODS place tissue hypoxia and reperfusion as a central feature of the initiation and continuation of the syndrome. Surgical patients are at risk of developing overt and covert tissue hypoxia and hypoperfusion due to anesthetic, surgical, and other factors; and it is known that surgical patients with poor cardiovascular reserve have a worse outcome postoperatively. A number of clinical studies have attempted to intervene early in surgical patients to prophylactically improve tissue perfusion in the perioperative period by augmentation of cardiac output. These studies demonstrate a reduction in mortality and morbidity in these groups of patients. A similar approach has been tried in other groups of critically ill patients, at a later state in the evolution of their illness; these studies have not shown any improvement in outcome. In surgical patients, data show that those with more coexisting pathology and worse cardiac function may benefit most from a treatment approach aimed at improving tissue perfusion; furthermore, this may result in cost savings. The implications for the management of the higher risk surgical patient are obvious. It may no longer be acceptable to undertake surgery in these patients without facilities to monitor and improve cardiac output and tissue perfusion.

Blood Circulation↗
PubMed1995

Sickle cell anemia, right atrial thrombosis, and the antiphospholipid antibody.

We report a patient with sickle cell anemia (homozygous Hb SS) and typical features of sickle chest syndrome but with no response to exchange transfusion. A right atrial thrombus was found, and antiphospholipid antibodies were detected in his blood. He responded to thrombolytic therapy. The relationship between right atrial thrombus and massive pulmonary embolus, and the implications of an additional thrombophilic state in sickle cell disease are discussed.

Adult↗
PubMed1995

A comparison of the efficacy of dopexamine and dobutamine for increasing oxygen delivery in high-risk surgical patients.

Peri-operative increase of oxygen delivery has been shown to reduce mortality in high-risk surgical patients. This study compares the effectiveness of dopexamine and dobutamine when used to increase cardiac output as part of a regimen to increase oxygen delivery. Sixteen surgical patients were randomly allocated to receive either dopexamine or dobutamine, which was increased to a stable dose defined as either oxygen delivery index > 600 ml/min/m2, or tachycardia > 20% above baseline, other dysrhythmias or angina. At this "stable" dose there were significant increases in cardiac index (2.4 +/- 0.2 vs 3.7 +/- 0.3 l/min/m2) and oxygen delivery (380 +/- 73 vs 579 +/- 40 ml/min/m2) in the dopexamine group (P < 0.05); but not the dobutamine group. Five out of eight patients receiving dopexamine and three out of eight receiving dobutamine reached target oxygen delivery. Three dobutamine patients, but no dopexamine patients, had angina or dysrhythmias. In preoperative high-risk surgical patients, dopexamine can allow greater increases in oxygen delivery than dobutamine, due to cardiac effects that limit the dobutamine infusion rate.

Adrenergic beta-Agonists↗
PubMed1995

Follicular fluid levels of midazolam, fentanyl, and alfentanil during transvaginal oocyte retrieval.

OBJECTIVE: To investigate the time course of changes in follicular fluid (FF) concentrations of midazolam (Roche Products Ltd., Welwyn Garden City, United Kingdom), fentanyl (Janssen Pharmaceuticals Ltd., Wantage, United Kingdom), and alfentanil (Janssen Pharmaceuticals Ltd.) during ultrasound-guided transvaginal oocyte collection. STUDY DESIGN: Forty-five patients with tubal infertility were randomized to receive a bolus IV dose of midazolam, fentanyl, or alfentanil for sedation during ultrasound-guided transvaginal oocyte collection. Paracervical block with lignocaine was given for analgesia. Simultaneous blood and FF samples were drawn at 5-minute intervals after the bolus dose for analysis of drug levels. RESULTS: Data were obtained on 15 women receiving midazolam and fentanyl and on 13 women receiving alfentanil. Plasma levels of all agents rose to a peak and then fell in an exponential fashion as was expected. The FF levels of the agents continued to rise significantly to 25 minutes after the bolus dose, although the absolute level was low when compared with the blood level. There were no significant differences in fertilization or pregnancy rates in the three groups, but patient numbers were small. CONCLUSION: We conclude that midazolam, fentanyl, and alfentanil are found in FF after a single IV dose, but further investigation needs to be undertaken to investigate any potential influence on fertilization and implantation rates.

Adult↗
PubMed1994

Effects of insertion depth and use of the sidearm of the introducer sheath of pulmonary artery catheters in cardiac output measurement.

OBJECTIVE: To investigate the effects of various insertion depths and sidearm functions of the introducer sheath of pulmonary artery flotation catheters on cardiac output measurement. DESIGN: Prospective, randomized, crossover study. SETTING: A general intensive care unit. PATIENTS: Ten patients who had a pulmonary artery flotation catheter placed in the right internal jugular vein as part of their clinical management. INTERVENTIONS: Cardiac output was measured at three insertion depths of the pulmonary artery catheter, each with a different rate of flow into the introducer sheath. MEASUREMENTS AND MAIN RESULTS: Significant differences of up to 23% occurred in the measurement of cardiac output under the various conditions. Cardiac output measurement is greater, the closer the injection port lies to the introducer sheath and the more open the introducer sheath sidearm. CONCLUSIONS: All users of pulmonary artery catheters should be alert to this problem. For reliable measurements of cardiac output by thermodilution, the cold saline injection port of the pulmonary artery catheter must be downstream of the introducer sheath, and the introducer sidearm must be closed.

Adult↗
PubMed1994

The cardiovascular changes associated with equipotent anaesthesia with either propofol or isoflurane. Particular emphasis on right ventricular function.

The differences in effects of anaesthetic agents on right ventricular function have not been studied. We have developed a cross-over study design to compare the effects of propofol and isoflurane on cardiac and specifically right ventricular function. Ten patients were anaesthetised with equivalent MAC of isoflurane to MIR of propofol. After measurements had been taken on the randomly assigned first agent the patients were crossed over to the other agent and measurements were repeated. Cardiac function was assessed using a pulmonary artery catheter with a fast response thermistor. There were no differences in heart rate or blood pressure between the two agents suggesting that equivalent anaesthetic doses had been given. There were significantly (P < 0.05) higher cardiac output (4.0 to 4.5 l.min-1), right ventricular ejection fraction (35.1 to 39.4%), stroke volume (35.4 to 39.6 ml) and right ventricular end-diastolic volume index (102 to 110 ml.m2-1) with propofol compared to isoflurane. We conclude that propofol results in improved right ventricular performance compared to isoflurane. We have also shown that anaesthetic agents can be compared using a cross-over study design, and have demonstrated that MAC of isoflurane and MIR of propofol can be directly compared. We suggest that propofol may be a more suitable agent than isoflurane for anaesthesia in patients who may already have impaired right ventricular function and in whom maintaining high cardiac output may be beneficial.

Aged↗
PubMed1993

A randomized clinical trial of the effect of deliberate perioperative increase of oxygen delivery on mortality in high-risk surgical patients.

OBJECTIVE: To assess the effect of deliberate perioperative increase in oxygen delivery on mortality and morbidity in patients who are at high risk of both following surgery. DESIGN: Prospective, randomized clinical trial. SETTING: A teaching hospital general intensive care unit, London, England. PATIENTS: A total of 107 surgical patients, who were assessed as high risk from previously identified criteria, were studied during an 18-month period. INTERVENTIONS: Patients were randomly assigned to a control group (n = 54) that received best standard perioperative care, or to a protocol group (n = 53) that, in addition, had deliberate increase of oxygen delivery index to greater than 600 mL/min per square meter by use of dopexamine hydrochloride infusion. OUTCOME MEASURES: Mortality and complications were assessed to 28 days postoperatively. RESULTS: Groups were similar with respect to demographics, admission criteria, operation type, and admission hemodynamic variables. Groups were treated similarly to maintain blood pressure, arterial saturation, hemoglobin concentration, and pulmonary artery occlusion pressure; however, once additional treatment with dopexamine hydrochloride had been given, the protocol group had significantly higher oxygen delivery preoperatively (median, 597 vs 399 mL/min per square meter; P < .001) and postoperatively (P < .001). Results indicate a 75% reduction in mortality (5.7% vs 22.2%; P = .015) and a halving of the mean (+/- SEM) number of complications per patient (0.68 [+/- 0.16] vs 1.35 [+/- 0.20]; P = .008) in patients randomized to the protocol group. CONCLUSION: Perioperative increase of oxygen delivery with dopexamine hydrochloride significantly reduces mortality and morbidity in high-risk surgical patients.

Aged↗
PubMed1993

Physiological scoring systems and audit.

Scoring systems designed to rate the severity of an illness are being used for comparison of hospital units to identify different standards of care and to allocate resources. One such scoring system is the Acute Physiology and Chronic Health Evaluation (APACHE) system which is designed to assess the severity of illness of patients in intensive care units (ICUs). It is widely assumed that different ICUs can be compared by the ratio of actual mortality to that predicted by the APACHE score. However, we suggest that the use of physiological data that can be influenced by medical and nursing intervention should not be used for audit. For example, by good care a patient may be made less severely ill and, therefore, may have a lower actual mortality while, at the same time, accumulating only a low APACHE score with low predicted mortality. This patient could have, therefore, the same mortality ratio as a patient treated inappropriately, who may have a higher actual mortality and a high APACHE score with greater predicted mortality. Paradoxically, the very accuracy of these scoring systems for assessing the severity of illness precludes their use for comparison and audit.

Humans↗
PubMed1993

Comparison of clinical information gained from routine blood-gas analysis and from gastric tonometry for intramural pH.

The measurement of gastric intramucosal pH (pHi) has been advocated to assist in decision-making for critically ill patients. To assess whether the information obtained from the measurement of pHi can be obtained from other measurements of metabolic acidosis, we studied 20 consecutive patients admitted to the intensive care unit. A mean of eight (range two to fourteen) data sets per patient were obtained, comprising measurement of arterial pH, pO2, pCO2, and oxygen saturation, tonometer balloon fluid pCO2, arterial pressures, and cardiac output. Bicarbonate concentration, base deficit or excess in blood and extracellular fluid, and pHi were calculated from these measurements. Relations between the variables and pHi were assessed by within-subject correlation comparisons. There were significant correlations (r > 0.6, p < 0.001) between markers of metabolic acidosis (base deficit in blood and extracellular fluid and bicarbonate concentration) and pHi. A blood base deficit of -4.65 or less and an extracellular-fluid base deficit of -6.13 or less could estimate pHi below 7.32 (lower limit of normal range) with sensitivity of at least 77% and specificity of at least 96%. There was no patient in whom either pHi or blood base deficit consistently reflected acidosis when the other variable did not. We conclude that the information that is obtained by gastric tonometry for pHi can be obtained more simply from measurements of metabolic acidosis; these variables can be calculated from routinely available blood-gas measurements.

Acidosis↗
PubMed1993

Propofol or midazolam for short-term alterations in sedation.

It is often necessary to adjust a patient's sedation level while they are in the intensive care unit. The purpose of this study was to compare propofol with midazolam for controlling short-term alterations in sedation. Twenty-three patients undergoing an interactive procedure, physiotherapy, during mechanical ventilation of the lungs were studied. The patients were randomly assigned to receive infusions of propofol or midazolam for sedation. Sedation was assessed using the method of Ramsay, where 3 is drowsy responding only to commands; and 5 is asleep with a slow response to light glabellar tap. Prior to physiotherapy sedation was deepened from 3 to 5 by increasing the sedative infusion rate, and level 5 was maintained during physiotherapy by adjusting the infusion rate whenever necessary. After physiotherapy, the sedative dose was reduced until level 3 was again achieved. During physiotherapy, sedation level 5 was achieved for 53.9% of the time with propofol but for only 25.7% with midazolam (P < 0.01). After physiotherapy, those patients sedated with propofol re-awakened to level 3 faster (8.3 +/- 2.3 min, mean +/- SE) than those receiving midazolam (92.8 +/- 35.0 min, P < 0.05). After physiotherapy, a further 1.8 +/- 0.5 dose adjustments were required to the midazolam infusion while only 0.4 +/- 0.2 adjustments were required to the propofol infusion (P < 0.05). During physiotherapy 3.0 +/- 0.5 dose adjustments to the propofol dose were required compared with 3.6 +/- 0.5 adjustments to the midazolam dose (NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗