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Biomedical subjects

M Finster

Publications and source records attributed to M Finster.

At least 37 records · Page 2Linked to original sources
PubMed1988

Pharmacokinetics of lidocaine in nonpregnant and pregnant ewes.

The pharmacokinetics of lidocaine were studied in nonpregnant and pregnant ewes. The maternal femoral vessels were cannulated and, on the day of study, the urinary bladder was catheterized. Lidocaine HCl, 4-5 mg/kg, was administered by IV injection over 60 seconds. Serial samples of arterial blood and urine were collected over 4 hours, and drug concentrations were determined using a gas chromatographic technique. The volume of the central compartment was greater in pregnant than in nonpregnant ewes (1.51 +/- 0.20 vs. 0.96 +/- 0.16 L/kg) as was the volume of distribution at steady state (Vdss): 3.24 +/- 0.40 vs. 1.88 +/- 0.32 L/kg. The volume of distribution during the terminal exponential phase of drug elimination (Vd beta) and total clearance of lidocaine (Cl) were also higher in pregnant animals: 4.17 +/- 0.50 L/kg and 99.6 +/- 8.5 ml.min-1.kg-1, respectively; compared to 2.46 +/- 0.48 L/kg and 44.1 +/- 6.5 ml.min-1.kg-1, in nonpregnant ewes. However, the balance between these changes in Vd beta and Cl did not result in a significant difference in the elimination half-life of lidocaine (38.1 +/- 2.1 minutes in nonpregnant and 31.9 +/- 3.0 minutes in pregnant ewes). If these data are applicable to humans, the risk of drug accumulation after repeated administration of lidocaine is no greater in pregnant than in nonpregnant patients.

Animals↗
PubMed1987

Effect of lidocaine on the asphyxial responses in the mature fetal lamb.

The effects of lidocaine on the fetal circulatory responses to asphyxia were evaluated in chronically instrumented pregnant sheep. Twenty-six preparations were studied. Animals were assigned to one of three groups. The animals in group I (N = 10) did not have umbilical cord occluders placed. Lidocaine at 0.1 mg X kg-1 X min-1 was infused to the mother for 180 min. The animals in group II (N = 11) had an umbilical cord occluder, which was inflated to induce fetal asphyxia (PaO2 15 mmHg) for 90 min. Occlusion was then maintained for an additional 180 min while lidocaine at 0.1 mg X kg-1 X min-1 was infused. The animals in group III (N = 5) also had an umbilical cord occluder inflated for 90 min. While occlusion was maintained for an additional 180 min, saline was infused, in place of lidocaine. The infusion rate of lidocaine of 0.1 mg X kg-1 X min-1 over 180 min resulted in a steady-state arterial lidocaine blood concentration in the mother of approximately 2.15 micrograms/ml. Fetal circulatory responses to asphyxia were evaluated before and after maternal infusion of lidocaine or normal saline. Measurements included heart rate, blood pressure, arterial pH, and blood gases. Cardiac output and organ blood flow were determined using the radio-labelled microsphere technique. In general, arterial and tissue lidocaine concentrations in asphyxiated fetuses were higher than those in the nonasphyxiated ones, the differences being significant in the brain, heart, liver, and adrenal glands.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Epidural↗
PubMed1985

Bupivacaine toxicity in pregnant and nonpregnant ewes.

The relative central nervous system and cardiovascular toxicity of bupivacaine was compared in pregnant and nonpregnant ewes during continuous infusion of bupivacaine into the jugular vein at the rate of 0.5 mg X kg-1 X min-1. In all animals, identical symptoms of toxicity occurred in the following order: convulsions, hypotension, respiratory arrest, and circulatory collapse. The dose of bupivacaine required to produce central nervous system (CNS) toxicity in the pregnant ewe tended to be lower than in the nonpregnant animal, although the difference was not statistically significant (P less than 0.1). However, the mean dose of bupivacaine resulting in cardiovascular collapse was significantly lower in pregnant ewes (5.1 +/- 0.7 mg/kg) than in nonpregnant animals (8.9 +/- 0.9 mg/kg). Similarly, bupivacaine blood concentrations at the onset of respiratory arrest and circulatory collapse were lower in the pregnant group, being 5.2 +/- 0.7 micrograms/ml and 5.5 +/- 0.8 micrograms/ml, respectively, versus 7.5 +/- 1.0 microgram/ml and 8.0 +/- 0.9 micrograms/ml, respectively, in the nonpregnant group (P less than 0.05). The concentration of bupivacaine in the brain of pregnant ewes at the time of cardiovascular collapse was significantly lower (P less than 0.01) than in the nonpregnant group (7.5 +/- 1.5 vs. 16.3 +/- 1.7 micrograms/g). The myocardial tissue concentration of bupivacaine also tended to be lower in the pregnant group, although the differences were not statistically significant (P less than 0.1).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Regional anaesthesia in obstetrics.

This review includes a brief discussion of the indications and pitfalls of regional anaesthetic techniques commonly used during parturition. Emphasis is given to the physiological changes of pregnancy and the potential effects on the fetus. The criteria for the choice of local anaesthetic are also presented.

Anesthesia, Conduction↗
PubMed1984

Hyperbaric bupivacaine for spinal anesthesia in cesarean section.

The efficacy and safety of 0.5% hyperbaric bupivacaine (Sensorcaine, Astra) was evaluated in 22 patients undergoing elective cesarean section under spinal anesthesia. The dose varied from 7.5 to 10 mg, (depending on the patient's height) which was significantly lower than previously reported. Patients were placed in head-down tilt immediately after subarachnoid injection. The mean spread of analgesia was to T3, which was reached in 10-15 min. Regression was complete in 258 +/- 16 min. Complete motor paralysis of lower extremities occurred in only two patients. Complete recovery of motor function in all patients was evident in less than 2.5 h. All infants were vigorous at birth and there were no serious maternal complications. The incidence of hypotension was 4.5%, the lowest reported as a consequence of spinal anesthesia in this group of patients. A technique involving the use of reduced doses of hyperbaric bupivacaine (0.5%) in conjunction with head-down tilt appears to be useful for spinal anesthesia for cesarean section.

Adult↗
PubMed1983

Combined intrauterine and extrauterine gestations: a review.

In a review of the world's literature on combined intrauterine and extrauterine pregnancies, 589 cases, including five cases currently reported from the Sloane Hospital for Women, were documented. Analysis of the literature revealed abdominal pain to be the most frequent presenting symptom. A combination of signs and symptoms, including abdominal pain, adnexal mass, peritoneal irritation, and an enlarged uterus, was the most significant finding in support of a presumptive diagnosis of combined gestations. At the Sloane Hospital for Women, the occurrence of both pelvic inflammatory disease and combined pregnancy is approximately three times the reported world incidence. This proportionate increase in both disease states may support a potential etiologic association between pelvic inflammatory disease and simultaneous intrauterine and extrauterine gestations.

Abdomen↗
PubMed1983

Etidocaine toxicity in the adult, newborn, and fetal sheep.

The systemic toxicity of etidocaine was compared in adult, newborn, and fetal sheep during continuous infusion of the drug into the jugular vein at the rate of 0.5 mg X kg-1 X min-1. All recipients exhibited symptoms of toxicity in the following order: convulsions, hypotension, respiratory arrest, and circulatory collapse. The dose of etidocaine required to produce CNS and cardiovascular toxicity was significantly different among the three age groups, being the highest in the fetus and the lowest in the adult. In contrast, no significant difference in etidocaine blood concentrations at the onset of each toxic symptom was observed among the groups except that convulsions and hypotension occurred at lower blood levels in the fetus as compared with the newborn and adult. Comparisons of etidocaine blood concentrations associated with the onset of convulsions and circulatory collapse (CC/CNS ratio) with those of lidocaine reported previously indicate that a narrower margin exists in adults and newborn following administration of etidocaine.

Acetanilides↗
PubMed1982

Chloroprocaine.

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Anesthetics, Local↗
PubMed1982

Pharmacokinetics of etidocaine in fetal and neonatal lambs and adult sheep.

Etidocaine, 2.5 mg/kg, was injected intravenously into either a nonpregnant adult sheep (N = 7), neonatal lamb (N = 7), or fetal lamb (N = 6), all with catheters in the femoral vessels and urinary bladders. Serial arterial blood and urine samples were obtained over 4 hours and analyzed for unchanged etidocaine using a gas chromatographic technique. The distribution and elimination half-lives of etidocaine in the blood of nonpregnant adults and newborn sheep were similar. The volume of distribution was significantly greater in the newborn (4.64 LK/kg) compared with the adult (1.52 L/kg) as was the total body clearance (87-4 vs 30.3 ml/min/kg). Renal clearance was also significantly greater in the newborn. The data indicate that the newborn lamb is capable of eliminating etidocaine as rapidly as the adult. Following injection of the drug into the fetus, fetal blood concentrations became undetectable after 30 minutes due to placental transfer into the maternal compartment.

Acetanilides↗
PubMed1981

Toxicity of lidocaine in adult, newborn, and fetal sheep.

The relative central nervous system and cardiovascular toxicity of lidocaine was compared in adult, newborn, and fetal sheep during continuous infusion of lidocaine into the jugular vein at the rate of 2 mg x kg-1 x min-1. An identical sequence of toxic manifestations occurred in the adult, newborn, and fetus: convulsions, hypotension, respiratory arrest, and circulatory collapse. Doses necessary to produce these manifestations were highest in fetuses and lowest in adults. For example, in order to elicit convulsions, 5.8 +/- 1.8 mg/kg of lidocaine was required in the adults, 18.4 +/- 2.2 in the newborns, and 41.9 +/- 6.0 in the fetuses. Measurements of lidocaine concentrations in blood demonstrated that these toxic symptoms occurred at levels which were not significantly different among the three groups. The results indicate that fetal and newborn lambs are no more sensitive to lidocaine toxicity than are adult sheep. The fact that the highest doses were required in the fetuses is probably related to the placental clearance of the drug into mothers and better fetal maintenance of arterial Po2 despite convulsions and respiratory arrest (cessation of breathing-like movements).

Animals↗
PubMed1979

Metabolism and measurement of chloroprocaine, an ester-type local anesthetic.

Blood levels of intact chloroprocaine were determined using a GLC procedure capable of detecting as little as 10 ng of chloroprocaine/ml of blood. It was necessary to detective plasma cholinesterases in collected samples by adding echothiophate iodide to blood sampling tubes. An extraction procedure, followed by a TLC separation and spectrodensitometric assay, was developed for measurement of the metabolite 2-chloro-4-aminobenzoic acid in plasma and urine. With these procedures, data were obtained showing that chloroprocaine is hydrolyzed rapidly by plasma cholinesterases. No unchanged drug could be detected in any blood samples obtained from volunteers who received chloroprocaine by intravenous infusion or from obstetric patients who had epidural anesthesia during labor and delivery. Blood levels of 2-chloro-4-amino-benzoic acid rose promptly with the administration of chloroprocaine and declined rapidly after drug administration. Most of the metabolite was recovered in urine.

Anesthesia, Epidural↗
PubMed1979

Pharmacokinetics of lidocaine in fetal and neonatal lambs and adult sheep.

The pharmacokinetics of lidocaine were studied in fetal and neonatal lambs and in pregnant and nonpregnant adult sheep. Catheters were implanted in the femoral vessels and in the urinary bladders of animals prepared for chronic study. Lidocaine, 5--10 mg/kg, was injected intravenously either into the fetus or newborn lamb or into nonpregnant adult sheep. Serial samples of arterial blood and urine were obtained over four hours and analyzed for unchanged lidocaine using a gas chromatographic technique. The elimination half-lives of lidocaine in the bloods of nonpregnant ewe, neonate and fetus were 31, 51 and 33 min, respectively. Total-body clearances in the neonate and adult were 53 and 41 ml/min/kg. The metabolic clearances of lidocaine were the same in both, and approximated hepatic blood flow. Renal clearance was greater in the neonate, which was attributed to differences in urinary pH values and extents of protein binding. Thus, despite differences in half-lives, the newborn lamb is as capable as the adult of clearing lidocaine.

Age Factors↗