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Biomedical subjects

M Tverskoy

Publications and source records attributed to M Tverskoy.

32 records · Page 2Linked to original sources
PubMed1988

Midazolam-thiopental anesthetic interaction in patients.

The effect of thiopental on the induction dose-response curve for midazolam was studied in nonpremedicated ASA physical status I and II patients. As an endpoint of anesthesia, ability to open eyes on command was used. Dose-response curves for thiopental, midazolam, and their combination were determined with a probit procedure and compared with an isobolographic analysis. Interaction between midazolam and thiopental was found to be synergistic (supraadditive). The degree of midazolam-thiopental anesthetic synergism in surgical patients was close to that reported previously in rats with loss of the righting reflex as an index of anesthesia.

Adult↗
PubMed1986

[A rare cause of subcutaneous emphysema].

A rare cause of subcutaneous emphysema is described which developed in two patients after epidural anaesthesia. Only two case reports could be found in literature describing similar conditions. The anaesthesia is performed using the "loss of resistance" technique with injection of air for the identification of the epidural space. Possible explanations for the development of the emphysema are discussed.

Aged↗
PubMed1985

Effects of anaesthesia induction drugs on circulation in denervated intestinal loop preparation.

The effect of anaesthesia induction drugs on the intestinal circulation was evaluated in an isolated loop preparation in 28 dogs. Selected intestinal loops were perfused with aortic blood by a pump at a constant pressure of 100 mmHg. A mixture of 86Rb and 9 microns spheres labeled with 141Ce was injected into the arterial cannula supplying the intestinal segment while mesenteric venous blood was collected for activity counting. Diazepam in a dose of 3 mg X kg-1 was accompanied by a significantly lower clearance (Cl-Rb), and permeability-surface area product (PS) than pentobarbitone; there were no differences between diazepam and pentobarbitone in total blood flow (BF), vascular resistance (VR) and oxygen consumption in the intestinal segments. Circulatory variable observed after midazolam, 8 mg X kg-1 and an additional 16 mg X kg-1, did not significantly differ from those seen during pentobarbitone. Ketamine in a dose of 8 mg X kg-1 was accompanied by a significantly lower BF, Cl-Rb, microsphere entrapment (Cl-Sph), PS, and higher VR and arterio-venous oxygen content difference. Sixteen mg X kg-1 of ketamine did not lead to any additional changes in determined variables of the intestinal circulation. Alpha-adrenoceptor blockade completely abolished vasoconstriction caused by ketamine, suggesting that the long-lasting vasoconstricting effect of ketamine on the intestinal circulation is mediated through catecholamines.

Anesthesia↗
PubMed1985

Intestinal circulation during inhalation anesthesia.

This study was designed to evaluate the influence of inhalational agents on the intestinal circulation in an isolated loop preparation. Sixty dogs were studied, using three intestinal segments from each dog. Selected intestinal segments were pumped with aortic blood at a constant pressure of 100 mmHg. A mixture of 86Rb and 9-microns spheres labeled with 141Ce was injected into the arterial cannula supplying the intestinal loop, while mesenteric venous blood was collected for activity counting. A very strong and significant correlation was found between rubidium clearance and microsphere entrapment (r = 0.97, P less than 0.0001), suggesting that the shunting of 9-microns spheres through the intestines reflects the arteriovenous shunting of blood. Nitrous oxide anesthesia was accompanied by a higher vascular resistance (VR), lower flow (F), rubidium clearance (Cl-Rb), and microspheres entrapment (Cl-Sph) than pentobarbital anesthesia, indicating that the vascular bed in the intestinal segment was constricted and flow (total and nutritive) decreased. Halothane, enflurane, and isoflurane anesthesia were accompanied by a much lower arteriovenous oxygen content difference (AVDO2) and oxygen uptake than pentobarbital or nitrous oxide. Compared with pentobarbital, enflurane anesthesia was not accompanied by marked differences in VR, F, Cl-Rb, and Cl-Sph; halothane at 2 MAC decreased VR and increased F and Cl-Rb while isoflurane increased VR and decreased F. alpha-Adrenoceptor blockade with phentolamine (1 mg . kg-1) abolished isoflurane-induced vasoconstriction, suggesting that the increase in VR was mediated via circulating catecholamines.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Inhalation↗
PubMed1985

Influence of fentanyl and morphine on intestinal circulation.

The influence of fentanyl and morphine on the intestinal circulation was evaluated in an isolated loop preparation in 37 dogs anesthetized with pentobarbital intravenously. Selected intestinal segments were pumped with aortic blood at a constant pressure of 100 mm Hg. A mixture of 86Rb and 9-micron spheres labeled with 141Ce was injected into the arterial cannula supplying the intestinal loop, while mesenteric venous blood was collected for activity counting. A strong correlation was found between the clearances of rubidium and microspheres (r = 0.97, P less than 0.0001), suggesting that the shunting of 9-micron spheres through the intestines reflects the shunting of blood through nonnutritive vessels. Intravenous fentanyl decreased oxygen uptake (O2up), and vascular resistance (VR), and increased blood flow (BF), rubidium and microsphere clearances (Cl-Rb, Cl-Sph, respectively), and permeability--surface area product (PS) in a dose-related fashion. Intravenous morphine in a dose of 1 mg X kg-1 increased Cl-Rb (nutritive BF) without changes in total (nutritive and nonnutritive) BF. This increase in nutritive BF is probably related to morphine-induced histamine release. Morphine in a dose of 5 mg X kg-1 was accompanied by vasoconstriction that was completely abolished by alpha-adrenoceptor blockade. The data suggest that morphine-induced intestinal vasoconstriction is mediated via a release of epinephrine, apparently from the adrenal medulla. It is concluded that changes in the intestinal circulation during anesthesia with narcotics might play a certain role in the cardiovascular homeostasis during anesthesia and surgery. An increase in oxygen content in portal venous blood, resulting from a decrease in intestinal oxygen uptake, should facilitate hepatic oxygenation.

Animals↗
PubMed1981

Biphasic change in serum potassium concentration following a single dose of succinylcholine chloride.

Serum potassium concentration during the thiopentone-succinylcholine induction of endotracheal anesthesia was examined in 53 patients undergoing elective surgery. There was no change in serum potassium after thiopentone. During muscle fasciculation serum potassium fell by 0.37 meq/L and returned to the initial level by the end of fasciculation. During muscle relaxation there was a further rise of 0.41 meq/L. The expected increase in serum potassium following the administration of succinylcholine is shown to be preceded by a transient decrease.

Adolescent↗
PubMed1980

Serum potassium in mother and fetus during normal delivery and cesarean section.

The influence of i.v. succinylcholine in term pregnant women on serum potassium of the fetus and of their own blood samples of two groups were taken to estimate the potassium level of women and their fetuses: 34 women delivering spontaneously and 24 by cesarean section using general endotracheal anesthesia. No significant differences were found in the newborns of serum potassium level of both groups, a finding which teaches, that succinylcholine given to the mother, has no significant influence on the serum potassium level of the newborn. Likewise, no significant change was foreseen in the serum potassium level in women after introduction of succinylcholine during cesarean section, in contrast to an increase of the serum potassium reported in the literature.

Adult↗
PubMedDate not supplied

Subarachnoid bupivacaine blockade decreases midazolam and thiopental hypnotic requirements.

STUDY OBJECTIVE: To test the hypothesis that subarachnoid bupivacaine blockade decreases hypnotic requirements for thiopental sodium and midazolam. DESIGN: Randomized, double-blind, placebo-controlled study. SETTING: Teaching hospital. PATIENTS: 53 nonpremedicated ASA physical status I and II adult male patients scheduled for elective lower abdominal, pelvic, or lower limb surgery. INTERVENTIONS: Intravenous injections of midazolam or thiopental were administered with or without subarachnoid bupivacaine blockade (12.5 mg) at the L3-L4 level. Thiopental or midazolam hypnotic requirements were determined using loss of ability to open eyes in response to verbal command as an endpoint. The thiopental requirements were determined by titration; the midazolam requirements were determined from dose-response curves obtained with bolus injections of predetermined doses of the drug. MEASUREMENTS AND MAIN RESULTS: Subarachnoid bupivacaine blockade decreased the hypnotic dose of thiopental from 3.40 +/- 0.68 mg/kg (mean +/- SD) with a dose range of 2.3 to 4.5 mg/kg (intramuscular saline) to 2.17 +/- 0.48 mg/kg with a dose range of 1.3 to 2.8 mg/kg (p < 0.005 for the difference). The ED50 value of midazolam decreased with the bupivacaine blockade, from 0.23 mg/kg (95% confidence limits: 0.08 to 0.38 mg/kg) to 0.06 mg/kg (0.01 to 0.14 mg/kg), with p < 0.0001 for the difference. CONCLUSION: Subarachoid bupivacaine blockade decreases hypnotic requirements for both thiopental and midazolam. The results suggest that the reduction in hypnotic requirements is due to the decrease in afferent input induced by spinal anesthesia.

Adult↗
PubMedDate not supplied

Effect of epidural bupivacaine block on midazolam hypnotic requirements.

BACKGROUND AND OBJECTIVES: The aim of the study was to determine the effect of epidural bupivacaine block on midazolam hypnotic requirements. METHODS: Sixty unpremedicated, ASA physical status I or II male patients, aged 45-65 years and scheduled for elective lower abdominal, pelvic, or lower limb surgery participated in this randomized, double-blind, placebo-controlled study. The study population was composed of three groups: Before administration of midazolam, patients in the first group received an intramuscular injection of 15 mL saline (M), those in the second group an intramuscular injection of 15 mL 0.5% bupivacaine (MIB), and those in the third group an epidural injection of 15 mL 0.5% bupivacaine at the L3-L4 level (MEB). Loss of the ability to respond to verbal command was used as an endpoint for the effect of midazolam injected intravenously in predetermined doses (five patients per dose) 30 minutes after a bupivacaine (or saline) injection. Midazolam dose-response curves were obtained by probit analysis. RESULTS: The midazolam median effective dose values for the hypnotic effect were 0.20 mg/kg (95% confidence limit, 0.10-0.27 mg/kg) in the M group; 0.10 mg/kg (0.06-0.22 mg/kg) in the MIB group; and 0.04 mg/kg (0.03-0.07 mg/kg) in the MEB group. The differences between the midazolam median effective dose values had high levels of significance: P < .00001 for MEB versus M, P < .002 for MEB versus MIB, and P < .01 for MIB versus M. CONCLUSIONS: Epidural bupivacaine block profoundly decreases midazolam hypnotic requirements. The most likely explanation for this effect is the reduction in afferent input induced by the block.

Aged↗