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Biomedical subjects

R M Grounds

Publications and source records attributed to R M Grounds.

At least 19 recordsLinked to original sources
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↗
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

Circulating fluoride changes and hepatorenal function following sevoflurane anaesthesia.

Sevoflurane, a new volatile inhalational agent, undergoes biotransformation to fluoride which is potentially nephrotoxic. We compared the effects of sevoflurane or isoflurane anaesthesia on hepatorenal function and serum fluoride concentrations in 50 ASA 1-3 patients undergoing major intra-abdominal surgery. No patient developed renal or hepatic dysfunction. Mean (SEM) peak fluoride concentrations were 23.1 (1.5) mumol.l-1 for sevoflurane and 5.4 (0.4) mumol.l-1 for isoflurane (p < 0.001). There was a significant correlation in the sevoflurane group between the total dose of agent (MAC h), the total fluoride production (r = 0.78, p = 0.0001) and peak fluoride concentration (r = 0.57, p = 0.003). There was no correlation between these variables in the isoflurane group.

Adult↗
PubMed1994

A simple method for the maintenance of oxygen saturation following intravenous induction of anaesthesia with propofol.

One hundred unpremedicated fit adult patients having elective minor day-stay surgery and general anaesthesia were randomly allocated to one of two groups. During 30 s of intravenous propofol administration (2.5 mg.kg-1), study group patients (n = 50) were instructed to take three vital capacity breaths of room air, whilst control group patients (n = 50) were given no specific instructions. Pulse oximetry was continuously recorded over the next 5 min and the lowest oxygen saturation was noted. Pre-induction oxygen saturation was the same for both groups, but the lowest median oxygen saturation in the study group patients was 94% versus 88% in the control group patients (p < 0.001). Oxygen saturation returned to the pre-induction value significantly earlier in the study group patients compared with controls (97 s vs 135 s, p < 0.01). These results demonstrate that significant desaturation occurs in patients following intravenous induction of anaesthesia with propofol. This desaturation may be attenuated by asking patients to take three vital capacity breaths of room air during induction of anaesthesia.

Adult↗
PubMed1994

Sevoflurane anaesthesia for major intra-abdominal surgery.

The cardiovascular effects and recovery characteristics of sevoflurane and isoflurane anaesthesia were compared in 30 gynaecological and 20 general surgical patients undergoing elective intra-abdominal surgery. Patients were randomly allocated to receive either sevoflurane or isoflurane as the volatile agent, in a balanced anaesthetic technique including morphine and atropine premedication and thiopentone, fentanyl, vecuronium and nitrous oxide. The concentration of volatile agent was titrated according to clinical variables. Mean heart rate, systolic and diastolic arterial pressure and duration of surgery did not differ between the two groups. Time to emergence from anaesthesia in the gynaecological patients was significantly faster after sevoflurane compared with isoflurane (p < 0.005). Sevoflurane provided stable anaesthesia during major intra-abdominal surgery.

Abdomen↗
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↗
PubMed1993

The peri-operative management of surgical insertion and removal of the intravenous oxygenator device (IVOX). A report of nine cases.

Intravenous oxygenation (IVOX) is a new technique for augmentation of gas exchange in patients who require near maximal conventional ventilatory support. Patients who require IVOX are, by definition, critically ill with a high expected mortality. At present, these high risk patients must be transferred to the operating theatre for the IVOX device to be inserted. This report describes the anaesthetic problems associated with nine patients in whom an IVOX device was inserted and removed in our institution. The mortality was six out of nine patients; all deaths occurred with the IVOX device in situ. Three patients died within 6 h of insertion. Four patients were female. The patients' ages ranged from 14 to 76 years. There were few immediate ventilation changes in the first 4 h after IVOX insertion. Inspired oxygenation concentration was reduced in only one patient. Positive end-expiratory pressure was not reduced. Peak inspiratory pressure decreased in four patients. Arterial oxygen tension increased in four patients (range 0.1-2.5 kPa) and decreased in five (range 0.1-3.4 kPa). Arterial carbon dioxide tension increased in one patient (0.3 kPa) and decreased in eight (range 0.1-2.7 kPa). Inotropic support with adrenaline, dobutamine and noradrenaline needed to be initiated or increased in eight patients. Eight patients required 2-4 units of blood to be transfused during IVOX insertion or in the following 2 h. One patient suffered an asystolic cardiac arrest during the operation, but was resuscitated successfully. Three patients survived to have the IVOX removed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

The use of dopexamine hydrochloride to increase oxygen delivery perioperatively.

Perioperative increases in oxygen delivery may reduce morbidity and mortality in certain groups of surgical patients. However positive inotropic drugs, such as dobutamine and epinephrine themselves, may increase oxygen demand. Dopexamine hydrochloride is a new dopamine analogue with action at beta 2-adrenoceptors and DA1 receptors, but it possesses no direct alpha-adrenoceptor activity. We assessed the suitability of dopexamine to increase oxygen delivery perioperatively in eight patients having vascular surgery and studied its effects on oxygen demand. Oxygen delivery was increased toward 600 mL.min-1.m-2 by intravenous (IV) fluid infusion and IV titration of dopexamine hydrochloride. Oxygen delivery could be increased preoperatively (375 +/- 43 to 552 +/- 50 mL.min-1.m-2, P < 0.05) with > 600 mL.min-1.m-2 being achieved in five patients. This increase was achieved without significant increase in total body oxygen consumption (114 +/- 10 to 123 +/- 7 mL.min-1.m-2 P > 0.05) or rate pressure product (13.7 +/- 2.8 x 10(3) to 13.5 +/- 2.1 x 10(3) mm Hg.beats/min, P > 0.05). Postoperatively oxygen delivery was increased again without an increase in oxygen consumption (126 +/- 10 mL.min-1.m-2, P > 0.05) or rate pressure product (14.2 +/- 0.9 x 10(3) mm Hg.beats/min, P > 0.05). Dopexamine hydrochloride may provide a method for increasing oxygen delivery perioperatively with only limited increase in total body or myocardial oxygen demand.

Adrenergic Agonists↗
PubMed1992

Isoflurane and propofol for long-term sedation in the intensive care unit. A crossover study.

Propofol and isoflurane have been reported recently to offer better sedation than alternative agents in patients who require long-term ventilation in the Intensive Care Unit. This is the first report of a direct comparison between propofol and isoflurane. Twenty-four patients predicted to require artificial ventilation for at least 48 h were entered into a randomised crossover study to monitor sedation quality and time to recovery from sedation. There were no significant differences between the two agents in either end-point, with over 95% optimal sedation achieved by the use of each drug. Few adverse events were noted. Technological advances in the administration of volatile agents as long-term sedatives in the Intensive Care Unit may facilitate their more widespread use.

Adolescent↗