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R J Hudson

Publications and source records attributed to R J Hudson.

At least 37 records · Page 2Linked to original sources
PubMed1991

Alfentanil pharmacokinetics in patients undergoing abdominal aortic surgery.

The pharmacokinetics of alfentanil, 300 micrograms.kg-1 IV, were determined in patients undergoing elective abdominal aortic reconstruction. The mean age (+/- SD) of the patients was 64.3 +/- 7.4 yr; their mean weight was 74.7 +/- 13.8 kg. Five patients underwent aneurysm repair and six had aortobifemoral grafting. Serum alfentanil concentrations were measured by gas-liquid chromatography in samples drawn at increasing intervals over a 24-hr period. A three-compartment model was fitted to the concentration versus time data. The volume of the central compartment and the volume of distribution at steady state (Vdss) were 0.44 +/- 0.022 and 0.63 +/- 0.32 L.kg-1, respectively. Total drug clearance was 6.4 = 1.9 ml.min-1.kg-1. The elimination half-time was 3.7 +/- 2.6 hr. Patient age was positively correlated with both Vdss and elimination half-time. There were no significant correlations between the pharmacokinetic variables and the duration of aortic cross-clamping, the duration of surgery, or the rate or total volume of IV fluids infused intraoperatively. In general surgical patients, the elimination half-time of alfentanil has been reported to be 1.2-2.0 hr. Although the elimination half-time of alfentanil was longer in patients undergoing abdominal aortic surgery, alfentanil was eliminated much faster than either fentanyl or sufentanil in this patient population.

Age Factors↗
PubMed1991

A comparison of desflurane and isoflurane in patients undergoing coronary artery surgery.

Animal studies indicate that desflurane and isoflurane have similar hemodynamic effects when administered in equipotent anesthetic concentrations. The authors compared desflurane and isoflurane, used as primary anesthetics for patients undergoing elective coronary artery bypass surgery whose left ventricular ejection fractions were greater than 0.34. After induction of anesthesia with thiopental (dose 180 +/- 45 mg [mean +/- standard deviation]) and fentanyl, 10 micrograms.kg-1, either desflurane or isoflurane was administered to maintain systolic blood pressure within 70-120% of, and heart rates less than 120% of, the patients' average preoperative values. If adjusting the end-tidal anesthetic concentration within the range of 0-2.0 MAC could not maintain these predefined hemodynamic limits, additional fentanyl or vasoactive drugs were used. Induction and maintenance of anesthesia was accompanied by a significant decrease in mean arterial pressure in both groups (desflurane 97 +/- 12 mmHg at control, decreasing to 71 +/- 5 mmHg during skin preparation; isoflurane 95 +/- 9 mmHg at control, 74 +/- 9 mmHg during skin preparation). One minute after sternotomy, mean arterial pressure in the isoflurane group had returned to control, 97 +/- 9 mmHg, which was significantly greater than in the desflurane group, 87 +/- 12 mmHg. Systolic arterial pressure was also significantly greater in the isoflurane group 1 min after intubation, during skin preparation, and 1 min after sternotomy. Otherwise, the hemodynamic effects of these volatile agents were similar. There were no differences between groups in the incidence of ECG changes indicative of myocardial ischemia prior to cardiopulmonary bypass, perioperative myocardial infarction, or perioperative mortality.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Apnoea and unconsciousness after apparent recovery from alfentanil-supplemented anaesthesia.

Several cases of recurrent respiratory depression progressing to apnoea and unconsciousness after apparent recovery from sufentanil have been reported recently. Alfentanil has the shortest elimination half-time of the narcotics used in anaesthesia, suggesting that it should be the least likely to cause postoperative respiratory depression. A case of recurrent unconsciousness and respiratory arrest after apparent recovery from alfentanil-isoflurane-nitrous oxide anaesthesia is reported. A total dose of 137 micrograms.kg-1 alfentanil was given over a 3.25-hr period to a 45-year-old female undergoing partial gastrectomy. Naloxone, 0.16 mg IV, rapidly restored spontaneous ventilation and consciousness. This case demonstrates that apnoea and unconsciousness can also recur after apparent recovery from alfentanil. Recovery room personnel should be aware of this phenomenon. Earlier detection may permit treatment before apnoea occurs. Patients given narcotic-supplemented anaesthesia should be monitored by capnography and/or pulse oximetry in the early postoperative period.

Adjuvants, Anesthesia↗
PubMed1990

Bioenergetic consequences of alopecia induced by Dermacentor albipictus (Acari: Ixodidae) on moose.

Fasting metabolic rates, respiration rates, respiratory minute volumes, and fasted weights were measured on three yearling moose (Alces alces (L.)) (Artiodactyla: Cervidae) infested with 50,000 winter ticks. Dermacentor albipictus (Packard) (Acari: Ixodidae), and on two uninfested controls. Infestations produced no detectable effects on fasting metabolic rates or weight changes. The influence of tick-induced alopecia on lower critical temperatures could not be assessed because of warm temperatures during the winter and spring trials. Destruction of winter hair accompanied a reduction in respiratory minute volumes and respiration rates of heat-stressed moose.

Alopecia↗
PubMed1989

Pharmacokinetics of sufentanil in patients undergoing abdominal aortic surgery.

The authors determined the pharmacokinetics of sufentanil, 12.5 micrograms.kg-1 iv in patients undergoing elective abdominal aortic surgery. The mean age (+/- SD) of the ten patients was 68.4 +/- 7.9 yr; their mean weight was 74.4 +/- 19.1 kg. Six patients underwent aortobifemoral grafting and four had abdominal aortic aneurysm repair. Serum sufentanil concentrations were determined in samples drawn at increasing intervals over a 24-h period. A three-compartment pharmacokinetic model was fit to the concentration versus time data. Total drug clearance was 15.0 +/- 3.2 ml.min-1.kg-1. The volume of distribution at steady-state (Vdss) was 8.7 +/- 4.5 l.kg-1. The elimination half-time were positively correlated with patient age. There were no significant correlations between the pharmacokinetic variables and the duration of aortic cross-clamping, the duration of surgery, or the rate or total volume of iv fluids given intraoperatively. In general surgical patients, the mean elimination half-time of sufentanil has been reported to be 2.7 h. When sufentanil is used in large doses as the primary anesthetic agent for patients undergoing abdominal aortic surgery, the long elimination half-time observed implies that recovery will take much longer than would have been anticipated from previously published pharmacokinetic data.

Aged↗
PubMed1988

Catecholamine responses to anesthetic induction with fentanyl and sufentanil.

In a randomized study, the authors examined the changes in plasma epinephrine and norepinephrine concentrations associated with induction of anesthesia and surgery in 33 patients with good ventricular function undergoing elective coronary artery surgery. After premedication with morphine and scopolamine, patients received either fentanyl, 100 micrograms/kg (n = 16), or sufentanil, 15 micrograms/kg, (n = 17), intravenously (IV), over 10 minutes to induce anesthesia. Metocurine, 0.42 mg/kg, IV, produced muscle relaxation. Arterial blood for plasma catecholamine determinations was drawn prior to induction, every two minutes throughout induction, one minute following endotracheal intubation, and one minute after sternotomy. Plasma epinephrine concentration was unchanged with either induction agent. Plasma norepinephrine concentration increased significantly after administration of either narcotic, peaked between six and ten minutes into induction, and returned to the preinduction value after intubation. Induction-related changes in arterial pressure and pulmonary capillary wedge pressure were significantly correlated with changes in the logarithm of plasma norepinephrine concentration. Similar degrees of endogenous norepinephrine release appear to accompany induction with equipotent doses of fentanyl and sufentanil in patients premedicated with morphine and scopolamine. Norepinephrine release may influence the hemodynamic response to induction with narcotics.

Anesthesia, Intravenous↗
PubMed1987

A randomized double-blind comparison of fentanyl and sufentanil anaesthesia for coronary artery surgery.

Using a randomized double-blind protocol the authors compared two narcotic anaesthetic regimens in 33 patients with good ventricular function undergoing coronary artery surgery. After premedication with morphine and scopolamine, patients received either fentanyl 100 micrograms X kg-1 (n = 16), or sufentanil 15 micrograms X kg-1 (n = 17), intravenously (IV) over 10 min to induce anaesthesia. Metocurine 0.42 mg X kg-1 provided muscle relaxation. No further IV anaesthetic agents were given. The haemodynamic response to induction, intubation, and surgery, differed minimally between agents. The degree of rigidity on induction was identical with both agents, as were the intervals following induction at which patients lost consciousness, regained consciousness, or met criteria for extubation. However, the interval until extubation criteria were met did correlate with the duration of cardiopulmonary bypass. Sufentanil 15 micrograms X kg-1, was clinically indistinguishable from fentanyl 100 micrograms X kg-1, when used as the primary anaesthetic agent for coronary surgery.

Aged↗
PubMed1986

Fentanyl oxygen anaesthesia for abdominal aortic surgery.

Patients who present for abdominal aortic surgery often have significant atherosclerotic disease which may involve the coronary arteries. Haemodynamic responses occurring during fentanyl (100 micrograms X kg-1) oxygen anaesthesia for abdominal aortic surgery were studied in 16 patients. Anaesthesia was induced with fentanyl 100 micrograms X kg-1 with no supplemental doses and metocurine-pancuronium mixture (4:1). In 13 of 16 patients hyperdynamic circulatory responses to surgical stimuli required treatment prior to aortic cross-clamping. Interventions instituted were sodium nitroprusside or nitroglycerin (n = 13), propranolol (n = 4), and diazepam (n = 4). The serum fentanyl concentration at time of response to surgical stimulus was 18.5 +/- 5.6 ng X ml-1 (range 7-27 ng X ml-1; time from induction 71 +/- 49 min, n = 9). Eleven of the 16 patients required treatment for postoperative hypertension. Five of the 16 patients developed myocardial ischaemia, defined as ST segment depression greater than 0.1 mV, at some time during the operative procedure. Unsupplemented fentanyl anaesthesia (100 micrograms X kg-1) was unable to maintain a hypodynamic circulation in patients having abdominal aortic operations.

Aged↗
PubMed1986

Pharmacokinetics of fentanyl in patients undergoing abdominal aortic surgery.

The authors determined the pharmacokinetics of fentanyl 100 micrograms X kg-1 iv in patients undergoing elective abdominal aortic surgery. The mean (+/- SD) age of the ten patients was 67.2 +/- 8.7 yr; their mean weight was 78.5 +/- 13.7 kg. Seven patients had aortic aneurysm repair, and the other three patients had aortobifemoral grafts. Serum fentanyl concentrations were determined from samples drawn at increasing intervals over a 24-h period. A three-compartment pharmacokinetic model was fit to the concentration versus time data. Total drug clearance was 9.8 +/- 1.8 ml X min-1 X kg-1. The volume of distribution at steady-state (Vdss) was 5.4 +/- 1.9 X 1 kg-1. Elimination half-time was 8.7 +/- 2.5 h. There were no significant correlations between these pharmacokinetic parameters and patient's age, duration of aortic cross-clamping, duration of surgery, intraoperative blood loss, or volume of iv fluids given intraoperatively. In healthy volunteers or patients undergoing general surgery, other investigators report mean elimination half-times for fentanyl ranging from 1.7 to 4.4 h. The prolonged elimination half-time in patients having abdominal aortic surgery has important clinical implications. In particular, recovery from large doses will take much longer than would have been anticipated from previously published fentanyl pharmacokinetic data.

Aged↗
PubMed1985

Telemetered heart rate as an index of energy expenditure in moose (Alces alces).

Metabolic rate, heart rate and respiratory rate of three adult moose were monitored simultaneously on selected days between January 1982 and October 1983. Heart rate was successfully monitored using two types of implanted radio transmitters. Metabolic rate was significantly (P less than 0.001) correlated with heart rate for individual animals (r = 0.94-0.98). The relationship was best described by an exponential equation. A mean weighted equation predicted metabolic rate within 9% of individual equations. In adult moose cows, heart rate was a more reliable predictor of energy expenditure than respiratory rate.

Animals↗
PubMed1985

Ranitidine does not alter pethidine disposition in man.

The effect of concurrent ranitidine administration on the disposition of pethidine was investigated in eight healthy male volunteers (19-33 years). The subjects received 70 mg i.v. pethidine HCl doses before and during ranitidine treatment (150 mg p.o. twice daily). Ranitidine therapy was not associated with significant alterations in pethidine elimination rate constant, volume of distribution at steady state, total body clearance, and 24 h urinary excretion. No alteration in pethidine oxidation to norpethidine was noted, as suggested by nonsignificant changes in lag time to appearance of quantifiable norpethidine in serum, time to peak concentration, peak concentration, area under the curve from time 0.24 h, and 24 h urinary excretion. It would appear that, unlike cimetidine, ranitidine does not interact pharmacokinetically with pethidine. Further studies are necessary to evaluate the potential clinical advantages of ranitidine vs cimetidine therapy in patients also receiving pethidine.

Adult↗
PubMed1984

Pharmacodynamic modeling of thiopental anesthesia.

We have pharmacodynamically modeled the relationship between the thiopental serum concentration and its effects on the electroencephalogram (EEG). Power spectral analysis was used to calculate the spectral edge, a measure of the underlying EEG frequency that characterizes the progressive slowing of the EEG induced by thiopental. Eight male volunteer subjects had venous thiopental serum concentrations measured, and 10 surgical patients had arterial serum concentrations measured. Thiopental was infused at a rate of 75 to 150 mg/min until a burst suppression EEG pattern was evident. Frequent blood samples were obtained during and after the infusion for measurement of serum thiopental concentrations, and the EEG was recorded for subsequent off-line power spectral analysis to calculate the spectral edge. With venous blood sampling, it was not possible to demonstrate significant hysteresis between the thiopental serum concentration and the spectral edge, allowing thiopental concentrations to be directly related to the spectral edge. With arterial blood sampling, significant hysteresis was present, requiring an effect compartment to relate concentration to effect. The half-time for equilibration (mean +/- SD) between concentration and response for the arterial data was 1.2 +/- 0.30 min. This value for Keo is consistent with known values for cerebral blood flow and thiopental brain: blood partition coefficient. Arterial-venous concentration differences cause the apparent lack of hysteresis with venous blood sampling. An inhibitory sigmoid Emax pharmacodynamic model optimally characterized the relationship between thiopental concentrations and the spectral edge. This model allows estimation of the thiopental serum concentration that causes one-half of the maximal EEG slowing (IC50), which is a measure of an individual's sensitivity to thiopental. Except for the hysteresis, there was no statistical difference in the parameters of the inhibitory sigmoid Emax pharmacodynamic model when venous and arterial blood samplings were compared. Arterial blood sampling offers some distinct advantages when pharmacodynamically modeling continuous, rapidly changing measures of drug effect, such as the EEG.

Adult↗
PubMed1984

The pharmacokinetics of thiopental in pediatric surgical patients.

Thiopental pharmacokinetics and protein binding were determined in 24 pediatric surgical patients with normal hepatic and renal function, ranging in age from 5 months to 13 yr. These pharmacokinetic data were compared with those from 11 adult patients previously studied at our institution. All pediatric patients received a single intravenous bolus of thiopental, 4.0 +/- 0.08 mg . kg-1 (mean +/- SD), while the adult patients received 6.0 +/- 0.74 mg . kg-1. Distribution phase kinetics and volume of distribution at steady state (Vdss) did not differ statistically between the two groups. The degree of serum protein binding of thiopental also was similar in pediatric and adult patients with free fractions of 13.2% +/- 1.5% and 13.6% +/- 1.3%, respectively. The two patient groups showed a marked difference in elimination half-time and clearance of thiopental. Total drug clearance was 6.6 +/- 2.2 ml . kg-1 . min-1 for pediatric patients and 3.1 +/- 0.5 ml . kg-1 . min-1 for adults (P less than 0.001). The elimination half-time of 6.1 +/- 3.3 hours found in pediatric patients was significantly shorter (P less than 0.005) than that for adults, 12 +/- 6 hours. Linear regression of the pediatric data failed to achieve significance (P = 0.06) for elimination half-time to increase with age, while clearance decreased (P less than 0.001) with increasing age. The shorter elimination half-time seen in infants and children was due solely to greater hepatic clearance. Thus, recovery time after large or repeated doses may be more rapid for infants and children than for adults because of the higher clearance.

Adolescent↗
PubMed1983

Prospective evaluation of radial and femoral artery catheterization sites in critically ill adults.

Prospective evaluation of 178 radial (RAD) and 114 femoral (FEM) artery catheters inserted in 231 critically ill adults in 2 ICUs was performed. FEM catheter duration (5.8 days) was greater than RAD (3.9 days, p less than .001). Most catheters were removed when no longer needed. Complication rates of RAD (7.5%) and FEM catheters (6.9%) were similar. Digital ischemia was the most common complication (3.5%) yet no digital necrosis occurred. Peripheral vascular disease (PVD), greater age, and greater catheter duration were not associated with more complications. Difficult percutaneous and surgical cutdown insertion of RAD catheters was associated with much greater complication rates. In conclusion, FEM and RAD artery catheters have acceptably low complication rates of 7%. Percutaneous FEM catheterization is recommended as a safe alternative to difficult RAD cannulation.

Adult↗