Effects of sevoflurane anesthesia combined with epidural block on renal function in the elderly: comparison with isoflurane

Purpose. Renal function declines with age, but little is known about the renal effects of the inhaled anesthetic sevoflurane in the elderly. We therefore compared the renal effects of sevoflurane and isoflurane anesthesia in elderly patients. Methods. Thirteen patients aged ≥70 years undergoing gastrectomy with epidural anesthesia combined with general anesthesia were randomly assigned to receive either sevoflurane (n = 7) or isoflurane (n = 6). Dopamine (3–5 μg·kg⁻¹·min⁻¹) was administered to all patients. Blood and urine samples were collected before, during, and after anesthesia. Serum and urinary inorganic fluoride was measured, and renal function tests were performed. Results. Serum inorganic fluoride was significantly elevated in both groups. The production of inorganic fluoride was significantly greater in the sevoflurane group, but the level did not exceed 50 μmol·l⁻¹ in any patient. No abnormalities were observed in blood urea nitrogen (BUN), serum creatinine, or urine volume in either group. The albumin excretion index increased during anesthesia and decreased after anesthesia in both groups. Creatinine clearance was unchanged in the sevoflurane group but fluctuated during and after anesthesia in the isoflurane group. α₁-Microglobulin (MG), β₂-MG, and urinary N-acetyl-β-d-glucosaminidase (NAG) excretion increased up to 3 h after anesthesia, and α₁-MG and β₂-MG excretion increased on postanesthesia day 3. Conclusion. In both groups, glomerular and tubular function were transiently affected, but no abnormalities were found in routine laboratory tests, suggesting that neither isoflurane nor sevoflurane in combination with dopamine and epidural anesthesia seriously affects renal function in the elderly. Received for publication on October 23, 1998; accepted on October 27, 1999     

Serum fluoride concentration after sevoflurane anesthesia in ethanol treated rats: Special reference to cytochrome P-450 in the liver

The relationship between serum concentration of inorganic fluoride (F^–) and cytochrome P-450 content after sevoflurane anesthesia was investigated in ethanol treated rats. Twenty male Wistar rats were randomly divided into 2 isocaloric diet groups of 10 rats each: one group receiving a standard diet and the other an ethanol diet. After 28 days on the diets the animals were administered 2.5% sevoflurane for 2hr with 30% oxygen and 70% nitrous oxide. Cytochrome P-450 and cytochrome b₅ were induced by the ethanol diet. In the ethanol diet group serum concentration of F^– was significantly higher than that of the standard diet group after sevoflurane anesthesia. These results suggest that cytochrome P-450 and b₅, which were induced by ethanol, enhanced sevoflurane defluorination.(Masaki E, Kondou T, Hirakawa J, et al.: Serum fluoride concentration after sevoflurane anesthesia in ethanol treated rats: special reference to cytochrome P-450 in the liver. J Anesth 6: 426–432, 1992)     

Liver and renal functions following total intravenous anesthesia using midazolam and fentanyl—comparison with enflurane-nitrous oxide anesthesia

Thirty patients undergoing lower abdominal surgery were studied to compare liver and renal functions in total intravenous anesthesia (TIVA) using midazolam and fentanyl with those in enflurane-nitrous oxide anesthesia (GOE). Patients were randomly divided into two groups of 15. In the TIVA group, anesthesia was induced with 0.3 mg·kg⁻¹ midazolam and maintained with 0.68 mg·kg⁻¹·h⁻¹ midazolam for 15 min followed by 0.125 mg·kg⁻¹·h⁻¹ midazolam and fentanyl. In the GOE group, anesthesia was induced with 5 mg·kg⁻¹ thiamylal and maintained with enflurane-nitrous oxide in oxygen. Plasma levels of aspartate aminotransferase, alanine aminotransferase (ALT), lactate dehydrogenase, total bilirubin, alkaline phosphatase, γ-glutamyl transpeptidase (γ-GTP), blood urea nitrogen (BUN), and creatinine (Cr) were measured before and at 1, 7, and 30 days after surgery. There were transient increases beyond the normal range in ALT and γ-GTP in both groups. BUN and Cr were within the normal range. There were no differences between the two groups regarding these parameters and the numbers with abnormally high levels of each parameter. In conclusion, liver and renal functions following TIVA using midazolam and fentanyl were the same as those following enflurane-nitrous oxide anesthesia. This work was performed at Kagawa Prefectural Central Hospital, and a part was presented at the 40th meeting of the Japan Society of Anesthesiology held in Morioka, Japan, in 1993     

F−-CO 3 2− interaction in IR spectra of fluoridated CO3-apatites

Summary Spectroscopic properties of fluoridated CO₃-apatites were studied by means of infrared (IR) absorption analysis. The peak of the IR band caused by CO ₃ ²⁻ ions at 875 cm⁻¹ shifted to a lower frequency with the degree of fluoridation. This result suggests that there is a significant interaction between F⁻ and CO ₃ ²⁻ ions in the apatite crystals. The interaction of both these ions is discussed with regard to the solubility behavior of fluoridated CO₃-apatites in the acetate buffer solution at pH 4.0 and at 37°C. Solubility of these fluoridated CO₃-apatites approached that of fluoridated hydroxyapatites at high fluoride content.     

Effects of nicardipine-induced hypotension on cerebrovascular carbon dioxide reactivity in patients with diabetes mellitus under sevoflurane anesthesia

Purpose The purpose of this study was to examine the effects of nicardipine-induced hypotension on cerebrovascular CO₂ reactivity in patients with diabetes mellitus under sevoflurane anesthesia. Methods Nineteen diabetic patients, and 11 nondiabetic patients (serving as controls), undergoing elective orthopedic, cardiovascular, or thoracic surgery were included in the study. The diabetic patients were divided into three groups according to the antidiabetic therapy they were receiving, i.e., diet therapy (n = 6), oral antidiabetic drugs (n = 7), and insulin (n = 6). Anesthesia was maintained with 1.0 minimum alveolar concentration of sevoflurane. Absolute and relative cerebrovascular CO₂ reactivity was calculated using a 2.5-MHz pulsed transcranial Doppler (TCD) probe for the continuous measurement of mean blood flow velocity in the middle cerebral artery (Vmca). The cerebrovascular CO₂ reactivity was measured both at baseline and during hypotension by increasing the ventilatory frequency by 4 to 7 breaths·min⁻¹. Nicardipine was used to induce hypotension. Results We found that values for the Bispectral index (BSI), baseline mean blood pressure, endtidal CO₂ (Pet_{CO 2}), and Vmca were essentially identical in all patients, irrespective of the type of antidiabetic treatment being taken. Values for absolute and relative CO₂ reactivity in insulin-dependent patients, at both baseline blood pressure and during hypotension, were lower than those in patients in the antidiabetic drug, diet, and control groups (during hypotension, absolute CO₂ reactivity: diet group: 3.2 ± 0.9; oral antidiabetic drug group: 3.2 ± 0.7; insulin group: 1.5 ± 0.6; control group: 3.4 ± 0.8 cm·s⁻¹·mmHg⁻¹, [P < 0.05 insulin group vs the other groups]; relative CO₂ reactivity: diet group, 6.3 ± 1.0; oral antidiabetic drug group, 6.5 ± 0.8; insulin group, 3.5 ± 0.8; control group, 6.5 ± 0.7%·mmHg⁻¹, [P < 0.05 insulin group vs the other groups]. Conclusion We concluded that cerebrovascular CO₂ reactivity in insulin-dependent patients is impaired during nicardipine-induced hypotension under sevoflurane anesthesia.     

Neuromuscular effects of sevoflurane in patients with myasthenia gravis

The current study evaluated the neuromuscular responses following administration of sevoflurane in 14 patients with myasthenia gravis (MG) (I–IIb in Osserman's classification) scheduled for thymectomy and in 11 control patients (ASA I–II) who underwent elective surgery. The electromyographic (EMG) response of the abductor digiti minimi was measured following train-of-four (TOF) stimulation of the ulnar nerve every 20 s. After induction of anesthesia with a combination of 3–4 mg·kg⁻¹ thiopental and 1–2 μg·kg⁻¹ fentanyl with 66% N₂O and oxygen, an inspired concentration of 4% sevoflurane was administered via a face mask for 7 min. Anesthesia was maintained during surgery with 66% N₂O in oxygen and with 1 minimum alveolar concentration (MAC) of end-tidal concentration of sevoflurane. The T1 (the amplitude of the first response) values decreased more profoundly in the MG patients than in the control patients at the end of surgery (P<0.05). Following administration of 4% sevoflurane for 7 min, the TOFR (the ratio of the fourth TOF to the first response) values revealed depressions greater than 10% of preinhalation values in 11 of 14 MG patients with a marked individual variation. This attenuated response was followed by a further depression of the TOFR values with increasing time of 1 MAC sevoflurane anesthesia. On the other hand, no notable changes were observed in patients with normal neuromuscular functions. The most significant factor that correlated with the depression of the TOFR values induced by 1 MAC sevoflurane was the anti-AchR antibody titers (P=0.029). Our results indicate that MG patients have an increased neuromuscular sensitivity to sevoflurane.     

Renal safety and extrahepatic defluorination of sevoflurane in hepatic transplantations

BACKGROUND: The main metabolic pathway for defluorination of sevoflurane in the liver produces inorganic fluoride (Fl). The metabolism and effect of sevoflurane on the kidney is not clear during anhepatic phase in liver transplantation. The goal of the present study was to investigate the metabolism and renal effect of sevoflurane by measuring plasma and urine inorganic fluoride, urinary N-acetyl-glucosaminidase (NAG), and plasma creatinine levels in patients undergoing liver transplantations. METHODS: After institutional approval and informed consent, we studied nine cases of orthotopic liver transplantation after anesthesia was induced with 5 mg . kg(-1) thiopental, 1 mug . kg(-1) fentanyl intravenously, the trachea was intubated after vecuronium bromide 0.1 mg . kg(-1). Anesthesia was maintained with sevoflurane (2%), O(2), and N(2)O at a total gas flow of 6 L . min(-1) using a semiclosed circle system with a sodalime canister. Blood and urine samples were obtained to measure plasma and urine fluoride concentrations and urinary NAG excretions before induction (P0), hourly during resection (P1, P2, P3), every 15 minutes during anhepatic phase (A1, A2, A3), hourly after reperfusion (neohepatic phase) (N1, N2, N3), and postoperative first hour (Po1). Preoperative (T0) and postoperative day 1 (T1), 3 (T3), 7 (T7) plasma blood urea nitrogen (BUN) and creatinine (Cr) levels were also recorded. RESULTS: Mean duration of surgery was 9:06 +/- 0:09 hours. Mean inorganic fluoride concentrations in plasma were in the range of 0.71 +/- 0.30 to 28.73 +/- 3.31 mumole . L(-1). In P3, N1, N2, N3, increases in plasma inorganic fluoride concentrations were significant (P < .05) and reached a peak value at Po1. The mean urine inorganic fluoride concentrations were 12.49 +/- 2.04 to 256.7 +/- 49.62 mumole . L(-1). In A2, A3, N1, N2, and N3, mean urine inorganic fluoride concentrations were significantly increased (P < .05) and the peak value was observed at Po1. Mean NAG concentrations in urine varied (5.6 +/- 1.6 IU . L(-1) to 12.5 +/- 1.14 IU . L(-1)) and peak level was observed at 30 minutes of the anhepatic phase (A2), which did not exceed the normal values for urine NAG levels (1.5 to 6.1 U . L(-1)). No impairment was observed in serum BUN and creatinine levels at any time. While there was only a slight increase in NAG during anhepatic phase, there was no change in plasma F1. CONCLUSIONS: Sevoflurane seemed to have minimal effect on kidney functions of BUN and Cr levels during liver transplantation. Although urine F1 and NAG levels increased during the anhepatic phase plasma F1, BUN, and Cr levels did not, suggesting that renal F1 production may occur in the absence of hepatic function. The renal effect of sevoflurane in chronic liver disease is controversial and must be investigated in further studies.     

Effects of Low-flow Sevoflurane Anesthesia on Renal Function: Comparison with High-flow Sevoflurane Anesthesia and Low-flow Isoflurane Anesthesia

Background: The safety of low-flow sevoflurane anesthesia, during which CF2 = C(CF3)-O-CH2 F (compound A) is formed by sevoflurane degradation, in humans has been questioned because compound A is nephrotoxic in rats. Several reports have evaluated renal function after closed-circuit or low-flow sevoflurane anesthesia, using blood urea nitrogen (BUN) and serum creatinine as markers. However, these are not the more sensitive tests for detecting renal damage. This study assessed the effects of low-flow sevoflurane anesthesia on renal function using not only BUN and serum creatinine but also creatinine clearance and urinary excretion of kidney-specific enzymes, and it compared these values with those obtained in high-flow sevoflurane anesthesia and low-flow isoflurane anesthesia.

Methods: Forty-eight patients with gastric cancer undergoing gastrectomy were studied. Patients were randomized to receive sevoflurane anesthesia with fresh gas flow of 1 l/min (low-flow sevoflurane group; n = 16) or 6-10 l/min (high-flow sevoflurane group; n = 16) or isoflurane anesthesia with a fresh gas flow of 1 l/min (low-flow isoflurane group; n = 16). In all groups, the carrier gas was oxygen/nitrous oxide in the ratio adjusted to ensure a fractional concentration of oxygen in inspired gas (FiO2) of more than 0.3. Fresh Baralyme was used in the low-flow sevoflurane and low-flow isoflurane groups. Glass balls were used instead in the high-flow sevoflurane group, with the fresh gas flow rate adjusted to eliminate rebreathing. The compound A concentration was measured by gas chromatography. Gas samples taken from the inspiratory limb of the circle system at 1-h intervals were analyzed. Blood samples were obtained before and on days 1, 2, and 3 after anesthesia to measure BUN and serum creatinine. Twenty-four-hour urine samples were collected before anesthesia and for each 24-h period from 0 to 72 h after anesthesia to measure creatinine, N-acetyl-beta-D-glucosaminidase, and alanine aminopeptidase.

Results: The average inspired concentration of compound A was 20 +/- 7.8 ppm (mean +/- SD), and the average duration of exposure to this concentration was 6.11 +/- 1.77 h in the low-flow sevoflurane group. Postanesthesia BUN and serum creatinine concentrations decreased, creatinine clearance increased, and urinary N-acetyl-beta-D-glucosaminidase and alanine aminopeptidase excretion increased in all groups compared with preanesthesia values, but there were no significant differences between the low-flow sevoflurane, high-flow sevoflurane, and low-flow isoflurane groups for any renal function parameter at any time after anesthesia.     

Comparison between sevoflurane and isoflurane anesthesia in pig hepatic ischemia-reperfusion injury

Purpose. Sevoflurane and isoflurane have been reported to exert protective effects against ischemia-reperfusion injury (IRI) in various organs. To compare the effect of sevoflurane anesthesia on liver IRI with that of isoflurane anesthesia, we performed the present study in pigs. Methods. Nineteen pigs were assigned to either the sevoflurane (n = 9) or the isoflurane group (n = 10). Hepatic warm ischemia was produced by 30-min hepatic artery and portal vein clamping beginning 90 min after the start of the inhalation anesthesia; this was followed by a 240-min reperfusion. To extend our evaluation, we evaluated the degree of IRI using various parameters (plasma α-glutathione-S-transferase [α-GST], lipid peroxide, and lactate concentrations), in addition to the conventionally used liver damage markers. Results. The lactate level was significantly higher under isoflurane than under sevoflurane at 120 min after reperfusion (4.0 ± 0.4 mmol·l⁻¹ vs 2.5 ± 0.3 mmol·l⁻¹; P < 0.05). How-ever, this difference had disappeared after 240 min of reperfusion. No significant differences between the two groups were observed in values for α-GST, lipid peroxides, aspartate aminotransferase, alanine aminotransferase, or lactic dehydrogenase. Conclusion. The extent of the hepatic IRI seen under sevoflurane anesthesia in pigs did not differ significantly from that seen under isoflurane, as judged from measurements of a number of parameters over a 240-min reperfusion period. Received: February 14, 2001 / Accepted: August 28, 2001     

Clonidine premedication for sevoflurane anesthesia in upper abdominal surgery

The effects of clonidine as a preanesthetic medication were compared with diazepam on clinical courses of sevoflurane anesthesia in 22 patients undergoing upper abdominal surgery. The patients were divided into two groups of 11 patients each according to preanesthetic medication: atropine 0.5 mg i.m. plus clonidine 0.3 mg p.o., or atropine 0.5 mg i.m. plus diazepam 10 mg p.o. 60–90 min prior to induction of anesthesia. Anesthesia was induced with fentanyl and thiopental, and was maintained with sevoflurane, 0.5%–1.5%, nitrous oxide and oxygen, supplemented with fentanyl, 0.5 μg·kg⁻¹·hr⁻¹. While only one patient needed a vasodilator in the clonidine group for treatment of hypertension, seven patients needed it in the diazepam group. Pain score after extubation was higher in the diazepam group than in the clonidine group. The time when patients responded to verbal command after discontinuation of anesthetics was similar in both groups. Therefore, clonidine pretreatment was useful for sevoflurane anesthesia in upper abdominal surgery.     

Effects of sevoflurane anesthesia on plasma inorganic fluoride concentrations during and after cardiac surgery

Purpose. Sevoflurane metabolism results in the production of inorganic fluoride, which is known to be nephrotoxic. Since marked changes in body temperature and hemodynamics in cardiac surgery affect sevoflurane metabolism, plasma inorganic fluoride concentrations may differ in this situation compared with other types of surgery. We therefore measured plasma inorganic fluoride concentrations during and after sevoflurane anesthesia in patients undergoing cardiac surgery. Methods. Sixteen patients undergoing coronary artery bypass grafting or valve replacement were premedicated with 5–10 mg midazolam and 0.5 mg scopolamine injected intramuscularly. Anesthesia was induced with 5–10 mg midazolam, 0.5–1 mg fentanyl, and 0.12–0.15 mg·kg⁻¹ vecuronium. Following tracheal intubation, anesthesia was maintained with oxygen, sevoflurane, and fentanyl. At the onset of cardiopulmonary bypass (CPB), sevoflurane was discontinued, and additional fentanyl, midazolam, and pancuronium were administered. Plasma inorganic fluoride concentrations were measured before anesthesia, immediately before and after CPB, and at 0, 2, 6, 12, 24, and 48 h after anesthesia. Results. The individual maximum plasma inorganic fluoride concentration was 19.2 ± 7.2 μmol·l⁻¹ (mean ± SD; range, 9.2–36.7). The mean plasma inorganic fluoride concentrations increased during anesthesia, but the rate of increase decreased after the initiation of CPB. Concentrations peaked at 2 h after anesthesia and decreased thereafter. The concentrations in three cases continued to increase 2 h after anesthesia. Conclusion. The plasma inorganic fluoride concentrations observed in patients undergoing cardiac surgery were below nephrotoxic levels. However, the decrease in mean fluoride concentration after anesthesia was slower than that in the previous study in general surgical patients. Received for publication on December 4, 1998; accepted on April 25, 1999     

Intravenous famotidine does not always change core temperature during general anesthesia

It has been reported that oral premedication with the H₂ receptor antagonist famotidine augmented intraoperative hypothermia. We again investigated whether the H₂ receptor antagonist famotidine significantly affected body temperature during open abdominal surgery under general anesthesia. We studied 20 female patients undergoing elective gynecological surgery. Participating patients were assigned randomly to one of two regimens: (1) 10 ml saline given intravenously just before induction of general anesthesia or (2) 20 mg famotidine in 10 ml saline given just before induction of general anesthesia. General anesthesia was induced by 2 mg·kg⁻¹ propofol and 0.1 mg·kg⁻¹ vecuronium. After tracheal intubation, anesthesia was maintained with sevoflurane (1%–2%) in nitrous oxide (2 l·min⁻¹) and oxygen (1 l·min⁻¹) along with 1–2 μg·kg⁻¹ fentanyl as needed. Tympanic temperature (T_Tym) was measured as the core temperature, and arteriovenous perfusion of the fingertip was evaluated using the forearmminus-fingertip skin-surface temperature gradient (Grad_a–f). T_Tym gradually and significantly decreased in both groups during anesthesia, and no significant differences in these values were observed between the two groups. Grad_a–f did not differ significantly between the two groups during anesthesia. We conclude that intravenous famotidine does not always change the core temperature during general anesthesia.     

A comparison between sevoflurane and propofol when combined with continuous epidural blockade in adult patients

Purpose. The effects of sevoflurane and propofol, in combination with continuous epidural blockade, on blood pressure control and time of recovery from anesthesia were compared. Methods. Adult patients were allocated to either a sevoflurane (n=54) or a propofol (n=64) group. Anesthesia was induced with either inhalation of 5% sevoflurane or intravenous administration of 2 mg·kg⁻¹ propofol. After an injection of vecuronium, the trachea was intubated and anesthesia was maintained with continuous epidural blockade, air/oxygen, and sevoflurane or propofol. The systolic arterial pressure was maintained within ±30% of that obtained on the ward. Results. The number of cases requiring a change in the dose of either anesthetics or vasoactive agents was not different between the groups. However, the arterial pressure and heart rate were more stable in the propofol group than in the sevoflurane group (P<0.05). The length of time before tracheal extubation was shorter in the sevoflurane group (10.4±5.2 min, mean±SD) than the propofol group (15.0±11.2 min,P<0.05). Conclusion. Propofol anesthesia, in combination with continuous epidural blockade, results in more stable intraoperative hemodynamics than sevoflurane anesthesia, but requries a longer recovery time and results in larger interindividual variability than sevoflurane anesthesia.     

A comparison of sevoflurane with halothane,enflurane, and isoflurane on bronchoconstriction caused by histamine

This study was conducted to assess the effect of sevoflurane on lung resistance and compliance, and its responsiveness to histamine. We studied eight dogs to compare the effect of sevoflurane, isoflurane, enflurane, and halothane on bronchoconstriction caused by histamine. Baseline values of pulmonary resistance (R_L) and dynamic pulmonary compliance (C_dyn) were measured prior to administration of histamine. Histamine (2, 4, and 8 μg · kg⁻¹) were administered iv, and the values of R_L and C_dyn at the time of peak effect were recorded. Under 1 or 2 MAC anaesthesia, sevoflurane as well as the other three anaesthetics had no bronchoactive effects. The four anaesthetics, including sevoflurane, demonstrated inhibitory effect on increases in R_L and decreases in C_dyn caused by histamine. At 1 MAC anaesthesia, % changes in R_L caused by 2, 4, or 8 μg · kg⁻¹ of histamine were 38 ± 11, 85 ± 21, or 132 ± 24% (mean ± SE) for halothane, and 65 ± 11, 132 ± 15, or 172 ± 19% for sevoflurane, respectively. Sevoflurane was less effective than halothane in preventing increases in R_L. In preventing decreases in C_dyn, sevoflurane was less effective than halothane only at 8 μg · kg⁻¹ of histamine under 1 and 2 MAC anaesthesia. There was no difference in attenuating effect on changes in R_L and C_dyn between sevoflurane and isoflurane or enflurane. We concluded that sevoflurane was less potent than halothane in attenuating changes in R_L and C_dyn in response to iv histamine. Cette étude a été réalisée dans le but d’évaluer les effets du sévoflurane sur la résistance et la compliance pulmonaires en réponse à l’histamine. Les effets du sévoflurane, de l’isoflurane, de l’enflurane et de l’halothane sur la bronchoconstriction induite par l’histamine sont comparés sur huit chiens. Avant l’administration d’histamine, on mesure les valeurs initiales de la résistance (R_L) et de la compliance dynamique (C_dyn) pulmonaires. L’histamine (2, 4, 8 μg · kg⁻¹) est administrée par la voie veineuse et les valeurs maximales de la R_L et de la C_dyn sont enregistrées. Les quatre anesthésiques, dont le sévoflurane inhibent l’augmentation de la R_L et la diminution de la C_dyn provoquées par l’histamine. A MAC 1 d’anesthésie, les pourcentages de changement de R_L produits par 2, 4, ou 8 μg · kg⁻¹ d’histamine sont respectivement de 38 ± 11, 85 ± 21, ou 132 ± 24% (moyenne + SD) pour l’halothane, et de 65 ± 11, 132 ± 15, ou 172 ± 19% pour le sévoflurane. Le sévoflurane est moins efficace que l’halothane pour prévenir les augmentations de R_L. Le sévoflurane est moins efficace pour prevenir la diminution de C_dyn mais seulement à 8 μg · kg⁻¹ d’histamine sous anesthésie à MAC 1 et 2. Le sévoflurane, l’halothane et l’isoflurane ne sont pas de différents pour amortir les changements de R_L et C_dyn. Nous concluons que le sévoflurane est moins puissant que l’halothane pour diminuer la réponse à l’histamine de la R_L et de la C_dyn.     

Propofol or sevoflurane anesthesia without muscle relaxants for thymectomy in myasthenia gravis

Background Myasthenia gravis is a challenging clinical condition due to its neuromuscular involvement. We sought to compare two non-muscle relaxant anesthetic techniques in patients undergoing trans-sternal thymectomy, evaluating the intra and postoperative conditions including extubation in the operating room. Methods Eight consecutive myasthenic patients undergoing trans-sternal thymectomy were prospectively randomized into two groups: propofol and sevoflurane. In both groups anesthesia was induced with propofol (2mg. Kg⁻¹) and intubation performed after topical anesthesia of the airway with lignocaine. Anesthesia was maintained in the propofol group (4 patients) with continuous propofol infusion (3–10 mg. Kg⁻¹., hr⁻¹) with oxygen and nitrous oxide and in the sevoflurane group (4 patients), with sevoflurane (end tidal 1–1.5%) in oxygen and nitrous oxide. Fentanyl was used for analgesia in both the groups. Intubating conditions, haemodynamic changes, neuromuscular transmission along with postoperative intensive care unit stay were evaluated. Data were evaluated using ANOVA, Chi-square test and Student'st test. Results Intubating conditions were good in all patients. There were no significant haemodynamic changes. All patients were extubated in the operating room and none had to be re-intubated for postoperative respiratory depression. Neuromuscular transmission showed minimal changes and at the end of the procedure the recovery was complete in all the patients. There were no other significant differences between the two groups studied. Conclusion These two anesthetic techniques allow early extubation of myasthenic patients in the operating room.     

Inhibition by 1,25 dihydroxycholecalciferol of hormonal secretion of rat parathyroid gland in organ culture

Summary The effect of vitamin D metabolites on parathyroid hormone secretion was studied using rat parathyroid gland cultured in basal medium Eagle containing 5% serum obtained from thyroparathyroidectomized rat, 1 mM magnesium, and calcium concentration varying from 0.75–2.25 mM, and radioimmunoassay for rat parathyroid hormone (rPTH). 1,25 dihydroxycholecalciferol (1,25(OH)₂D₃), 5×10⁻¹⁰−2.5×10⁻⁸M, consistently decreased rPTH secretion in dose-related manner; the effect reached steady state after 24 hin vitro addition of 1,25(OH)₂D₃ and was also observed at different medium calcium concentrations (0.75, 1.25, 1.75 mM). Comparison of dose-responses for inhibitory activity of some vitamin D metabolites on rPTH secretion showed: 1,25(OH)₂D₃=1,24,25(OH)₃D₃>1α OHD₃>25 OHD₃. Cholecalciferol (10⁻⁵M), 24,25-dihydroxycholecalciferol (10⁻⁸−10⁻⁶M) and 25,26-dihydroxycholecalciferol (5×10⁻⁹−5×10⁻⁷M) did not inhibit rPTH secretion. Analysis of structural activity relation of vitamin D metabolites studied indicated that 1α or pseudo-1α hydroxylated metabolites or analogs were active in inhibiting rPTH secretion, while, non-1α hydroxylated metabolites were without or were weakly inhibitory only at very high concentrations. This study provides further evidence for a direct role of 1,25(OH)₂D₃ on a negative feedback loop for regulation of parathyroid gland function.     

紧闭循环麻醉时七氟醚对病人肝肾功能的影响

目的 评价紧闭循环麻醉时七氟醚对病人肝肾功能的影响.方法 拟行普外科手术病人40例,ASA Ⅰ或Ⅱ级,年龄20～60岁,随机分为2组(n=20),麻醉诱导后S1.组和S2组分别吸人6%～8%国产或进口七氟醚,新鲜气流量2～4 L/min,2～3 min后调整新鲜气流量至0.18～0.30 L/min,随后维持七氟醚呼气末浓度2.6%～3.5%.于术前、术毕、术后1、2、3和5 d时测定血清丙氨酸转氨酶(ALT)、天冬氨酸转氨酶(AST)活性、总胆红素(TB)、肌酐(Cr)、尿素(BUN)、β2-微球蛋白(β2-MG)浓度和尿液β2-MG浓度.结果 与术前比较,术毕、术后1、2 d时两组尿液β2-MG浓度升高(P<0.05),术后1～5血清ALT、AST活性和TB、Cr、BUN和β2-MG浓度差异无统计学意义(P0.05);各指标组间比较差异无统计学意义(P0.05).结论 紧闭循环麻醉时七氟醚对病人肝肾功能无明显影响.     

Evaluation of cerebrovascular carbon dioxide reactivity in patients with diabetes mellitus under sedative doses of propofol

The present study compared cerebrovascular CO₂ reactivity in diabetic patients on different treatment modalities under sedative doses of propofol. Fifteen patients with diabetes mellitus (on three different antidiabetic treatment modalities) who required mechanical ventilation during intensive care therapy were studied, sedation during mechanical ventilation being maintained using propofol. As controls, 6 patients without diabetes were monitored. A 2.5-MHz pulsed transcranial Doppler probe was attached to the head of the patient at the right temporal window for continuous measurement of mean blood flow velocity in the middle cerebral artery (Vmca). After establishing baseline values of Vmca and cardiovascular hemodynamics, end-tidal CO₂ was decreased by increasing ventilatory frequency by 5–8 breaths·min⁻¹. Values for absolute and relative CO₂ reactivity in insulintreated patients were lower than those in the other three groups (absolute CO₂ reactivity [means ± SD]: control, 3.1 ± 0.6 cm·s⁻¹·mmHg⁻¹, diet, 3.8 ± 1.4 cm·s⁻¹·mmHg⁻¹; oral antidiabetic drug 3.2 ± 0.9 cm·s⁻¹·mmHg⁻¹; insulin, 1.1 ± 0.6 cm·s⁻¹·mmHg⁻¹; P = 0.002). The present study shows that insulin-treated diabetic patients probably have lower cerebrovascular CO₂ reactivity under propofol anesthesia than control patients or diabetics treated with dietary therapy or oral hypoglycemics.     

6-keto-prostaglandin E1-stimulated bone resorption in organ culture

Summary Previous investigations have shown that prostaglandin E₂ (PGE₂), 13,14-dihydro-PGE₂, and prostacyclin (PGI₂) are among the most potent prostaglandin stimulators of bone resorption. 6-Ketoprostaglandin F_1α (6-keto-F_1α; also called 6-oxo-prostaglandin F_1α), a metabolite of PGI₂ formed by spontaneous hydrolysis, has little bone resorptive or other biological activity. The present study demonstrated that another metabolite of PGI₂, 6-keto-prostaglandin E₁ (6-keto-PGE₁; also called 6-oxo-prostaglandin E₁), was active in stimulating bone resorption in fetal rat long bone organ culture. 6-Keto-PGE₁ stimulated significant release of previously incorporated⁴⁵Ca over the concentration range of 10⁻⁹ to 10⁻⁵ M. The potency of 6-keto-PGE₁ was one-twelfth that of PGE₂. If 6-keto-PGE₁ is formed by bone or adjacent tissues, or reaches bone through the circulation, it could significantly affect bone mineral metabolism.     

Does sex difference influence the neuromuscular blocking potencies of vecuronium?

One hundred and fifty patients of ASA class I–II undergoing elective surgery were given vecuronium 0.1 mg·kg⁻¹ under fentanyl- (NLA), halothane, enflurane, isoflurane, or sevoflurane anesthesia, and the spontaneous recovery was monitored to study the sex differences as to onset time, duration [(T₁, train of four (TOF)], and recovery index (T₁, TOF). The onset time was significantly shorter in women than in men under isoflurane and sevoflurane anesthesia. No significant differences were seen between the sexes in terms of duration and recovery index of both T₁ and TOF. We suggest that the results regarding onset time were due to the differences in distribution volume and extracellular fluid volume influenced by the proportions of lean body mass, fat tissue, and the occasional menstruation in women. It remains unclear, however, whether or not the effects of volatile gases to the sensitivity of receptors may contribute to the observed sex difference. Similar durations and recovery indexes in any anesthetic method indicate that the drug's rate of elimination is similar between the sexes. In conclusion, female patients favor the rapid onset of vecuronium when used under isoflurane or sevoflurane, but the recovery from the paralysis seems to be the same between the sexes regardless of the type of general anesthesia used.