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Biomedical subjects

M Takaori

Publications and source records attributed to M Takaori.

At least 19 recordsLinked to original sources
PubMed1992

Plasma concentrations of lignocaine after obturator nerve block combined with spinal anaesthesia in patients undergoing transurethral resection procedures.

Bilateral obturator nerve block has become a widely accepted technique to avoid adductor contraction during transurethral resection of prostate or bladder tumours. However, little is known about plasma lignocaine concentrations after the block. We conducted this study to assess a safe dose of lignocaine for injection in obturator nerve block. Bilateral obturator nerve block was performed with the aid of a peripheral nerve stimulator in 12 patients after spinal anaesthesia. In group I (n = 6), patients received 2% lignocaine 10 ml (200 mg) for the block; those in group II (n = 6) received 2% lignocaine 15 ml (300 mg). The block was satisfactory and no single adductor contraction was observed in either group during surgery. The peak plasma concentrations of lignocaine were 2.28 (SD 0.29) micrograms ml-1 and 3.75 (0.79) micrograms ml-1 in groups I and II, respectively. The greatest plasma concentration was 5.07 micrograms ml-1 in a patient of group II. There were no symptoms suggesting systemic toxicity. We conclude that bilateral obturator nerve block may be performed safely and effectively with 2% lignocaine 10 ml with the aid of a peripheral nerve stimulator in patients undergoing transurethral resection procedures with spinal anaesthesia.

Aged↗
PubMed1991

Pulmonary gas exchange and ventilation-perfusion relationships during hypocapnia and thoracotomy in anaesthetized dogs.

The effects of hypocapnia and thoracotomy, both individually and combined, on pulmonary gas exchange and distribution of ventilation-perfusion ratio (Va/Q) were studied in anesthetized and paralyzed mongrel dogs by the six inert gas elimination technique. Normocapnia (PaCO2 35 mmHg) and hypocapnia (PaCO2 20 mmHg) were produced sequentially by varying the inspired CO2 concentration. Thoracotomy was performed at the fourth intercostal space. When ventilation was changed from normocapnia to hypocapnia without thoracotomy, PaO2 decreased from 160 +/- 10 to 147 +/- 11 mmHg and Qs/Qt increased from 0.0 +/- 0.0 to 0.6 +/- 0.7%. However, no change was observed in perfusion distribution following thoracotomy during normocapnia, PaO2 decreased from 160 +/- 10 to 113 +/- 15 mmHg together with a shift of perfusion toward the low Va/Q region. However, no change was observed in Qs/Qt. When ventilation was changed from normocapnia to hypocapnia with thoracotomy, PaO2 decreased from 113 +/- 15 to 98 +/- 12 mmHg and Qs/Qt increased from 0.3 +/- 0.8 to 3.4 +/- 2.0%. After thoracotomy, a shift of perfusion toward the low Va/Q region was observed, which was probably responsible for the decrease in PaO2. The decrease in PaO2 during hypocapnia was due to an increase in the true shunt rather than the development of low Va/Q region. Hypocapnia combined with thoracotomy produced a further reduction of PaO2 and a greater increase in Qs/Qt.

Anesthesia, Intravenous↗
PubMed1991

Perioperative autotransfusion: haemodilution and red cell salvaging.

We have treated 129 cases of massive haemorrhage during surgery using our combined autotransfusion technique (HAT and SAT). No adverse reactions or complications have been noted and additional homologous blood transfusion has not been required. In addition, circulatory dynamics have been satisfactorily maintained. Although the red cell recycle rate has been maintained at over 85%, the salvaging rate of blood in the operating field has not yet reached 80%. Approximately 30% of the surgical haemorrhage appears to be discarded with surgical sponges or flow out of the operating field. Clearly the cooperation of surgeons is an important factor for success with SAT. Success in autotransfusion may be accomplished by combinations of autotransfusion techniques.

Blood Transfusion, Autologous↗
PubMed1991

Influence of nicardipine on post-hypoxic injury in the isolated perfused rat liver.

We investigated microcirculatory changes and hepatocellular injury due to hypoxia/reoxygenation and the effects of nicardipine, a calcium channel blocker, using the isolated perfused rat liver technique. Liver perfusion was carried out in three consecutive phases: 30-min pre-hypoxia perfusion, 120-min hypoxia perfusion and 30-min reoxygenation perfusion in two groups, a control (n = 5) group and a nicardipine group (n = 5). In the nicardipine group, nicardipine (2 x 10(-6) M) was added to the perfusate prior to the hypoxia perfusion. Intrahepatic volumes, sinusoidal volume and extravascular volume accessible to albumin, were assessed by the multiple indicator dilution technique. Though 120-min hypoxia per se caused only a slight increase in the lactate dehydrogenase (LDH) release and no significant alterations in perfusion pressure and intrahepatic volumes, reoxygenation elicited hepatocellular injury assessed by the LDH level in the perfusate along with a substantial increase in perfusion pressure and an increase in extravascular volume. Nicardipine pretreatment attenuated the increase in LDH level, perfusion pressure and intrahepatic volumes after reoxygenation, but there were no difference in liver microcirculation during 120-min hypoxia. The data of the current study emphasized the crucial role of Ca2+ influx in hypoxic/reoxygenation hepatocellular injury and suggested that a direct vasodilating effect of nicardipine on the intrahepatic vasculature during hypoxia is unlikely as the mechanism for its cytoprotective effects.

Animals↗
PubMed1991

Comparative effects of halothane, isoflurane, and sevoflurane on the liver with hepatic artery ligation in the beagle.

Recently, there has been increasing interest in the alterations in splanchnic and hepatic circulation and preservation of hepatic oxygenation and function during anesthesia and surgery. However, the effects of volatile anesthetics under a condition of marginal hepatic oxygen supply are not well understood. Using a crossover design, we therefore studied the effects of equianesthetic concentrations (1.5 MAC) of halothane, isoflurane, and sevoflurane on hepatic oxygenation and function in nine beagles in which the hepatic artery had been ligated. Portal blood flow was measured by an electro-magnetic flow meter. Hepatic function was assessed by indocyanine green elimination kinetics. While cardiac output and mean arterial pressure were greater during halothane anesthesia than during isoflurane and sevoflurane anesthesia, portal blood flow and hepatic oxygen supply were significantly less during halothane and sevoflurane anesthesia than during isoflurane anesthesia. With regard to hepatic oxygen uptake, there was a significant difference between halothane (2.7 +/- 1.2 ml.min-1 x 100 g-1) and sevoflurane (3.7 +/- 2.0 ml.min-1 x 100 g-1; P less than 0.05). Consequently, the hepatic oxygen supply/uptake ratio and the hemoglobin oxygen saturation and oxygen partial pressure in hepatic venous blood during sevoflurane anesthesia were significantly less than they were with the other anesthetics. Indocyanine green clearance was better preserved during sevoflurane anesthesia (39.7 +/- 12.0 ml.min-1) than during halothane anesthesia (30.9 +/- 8.4 ml.min-1; P less than 0.05). We conclude that sevoflurane is accompanied by a smaller oxygen supply/uptake ratio than is halothane and isoflurane, while it preserves hepatic function.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthetics↗
PubMed1991

[Changes in blood sugar levels following infusion of lactated Ringer's solution with various concentrations of potassium and glucose].

Lactated Ringer's solution was prepared, in which concentration of potassium was either 10 or 20 mEq.l-1, and that of glucose was 1.4%. Each preparation was infused into 10 patients who underwent surgical operations under general anesthesia. Effects of this fluid therapy on changes in serum potassium and blood sugar were studied comparing with infusion of lactated Ringer's solution in which concentration of potassium was 10 mEq.l-1, and glucose was 0.7%. Both serum potassium and blood sugar levels were maintained within normal ranges with the lactated Ringer's solution containing 20 mEq.l-1 of potassium and 1.4% of glucose. On the other hand, the former tended to decrease and the latter tended to increase with the lactated Ringer's solution containing potassium 10 mEq.l-1 and glucose 1.4%. We consider that the homeostatic effect with the lactated Ringer's solution containing 20 mEq.l-1 of potassium and 1.4% of glucose would be to lower blood glucose level by concomitant intracellular influx of potassium and glucose. Therefore these high potassium lactated Ringer's solutions balanced adequately with glucose are useful for fluid therapy during surgical procedure under general anesthesia.

Adult↗
PubMed1991

[Effect of superimposed high frequency oscillation on pulmonary edema induced by intrapulmonary injection of hydrochloric acid in dogs].

Effect of superimposed high frequency oscillatory ventilation on pulmonary gas exchange was investigated in seven anesthetized and paralyzed dogs with pulmonary edema induced by intrapulmonary injection of hydrochloric acid. Efficacy of the ventilatory modes (HFO:6 Hz and 12 Hz) was evaluated observing changes in ventilation-perfusion mismatch, which was demonstrated by using six inert gas elimination method. The ventilation with 6 Hz HFO had no significant effect on PaO2, true shunt, and perfusion distribution. With 12 Hz HFO, PaO2 showed a tendency to increase from 57 +/- 18 mmHg at IPPV to 144 +/- 117 mmHg (0.05 less than P less than .01), and the true shunt decreased from 42.2 +/- 29.0% at IPPV to 16.6 +/- 25.8% (P less than 0.05). However, no change appeared in the perfusion distribution. During the ventilation with 12 Hz HFO increased mean airway pressure produces a PEEP-like effect, which may improve the pulmonary gas exchange by opening small airways, namely a decrease in the true shunt rather than an improvement in the ventilation-perfusion maldistribution.

Animals↗
PubMed1991

[Hepatic circulation and anesthesia].

Hepatic artery blood flow changes to buffer portal blood flow alterations, maintaining a constant total hepatic blood flow. Portal blood flow is regulated by preportal organs, such as intestine, pancreas and spleen. The liver plays an important role as a blood reservoir for cardiovascular homeostasis. Hepatic blood volume is mobilized actively to the systemic circulation by sympathetic stimulation. Sinusoid, the specialized capillary of the liver, and Disse's space are separated by endothelial cells, which have numerous fenestrations, allowing effective exchanges of solutes between hepatocytes and blood. Unidirectional blood flow in the acinus causes functional differences of hepatocytes according to the lobular zones. Although the majority of anesthetics decreases liver blood flow in a dose dependent manner, halothane inhibits hepatic arterial buffer response, while isoflurane and narcotics preserve it. Energy depletion, cellular acidosis, alteration of calcium homeostasis and superoxide-induced membrane damage, are all implicated as important factors for ischemia-induced liver injury. A better understanding of ischemia-induced derangements of cell function will lead to more rational preservation of the liver cells in the future.

Anesthetics↗
PubMed1991

[Intraoperative fluid therapy by lactated Ringer's solution with various concentrations of potassium].

Lactated Ringer's solutions, whose concentration of potassium was 10 or 20 mEq.l-1, were infused into 10 and 9 patients undergoing surgical operations under general anesthesia, respectively. Effects of these fluid therapies on serum potassium and blood sugar were studied comparing with the effect of infusion of regular lactated Ringer's solution. A decrease in serum potassium concentration seen with the regular lactated Ringer's solution during the surgery was minimized with the lactated Ringer's solutions of 10 or 20 mEq.l-1 of potassium. With the lactated Ringer's solutions of higher concentrations of potassium, an increase in blood sugar level, which was noted with the regular lactated Ringer's solution, was not observed although all the lactated Ringer's solutions contained 0.7% of glucose. Furthermore, base excess remained at a normal level in patients of high potassium groups, but it decreased in patients of the regular potassium group. Lactated Ringer's solutions of high potassium levels are useful to maintain serum potassium and glucose levels at more normal levels during surgical procedures under general anesthesia.

Adult↗
PubMed1991

[A simple expression of the intrapulmonary ventilation-perfusion ratio distribution curves].

We propose a method to express the intrapulmonary ventilation-perfusion distribution curves obtained by 6 inert gas elimination technique. A VA/Q distribution curve was obtained by calculating the amount of perfusion distributed in each fraction of the VA/Q as percentage of the cardiac output and then averaging them to obtain a single distribution curve. By this method, it is possible to simplify the representation of the distribution curve, to clarify the serial changes through the experiment, and further to compare different patterns in several experimental groups.

Humans↗
PubMed1990

Effect of hemodilution on capillary and arteriolovenous shunt flow in organs after cardiac arrest in dogs.

The purpose of this study was to observe the changes in capillary and arteriolovenous shunting blood flow after cardiac arrest and subsequent resuscitation by venous return occlusion produced by inflation of an intra-atrial balloon and cross-clamping of the ascending aorta, and to determine how hemodilution might modify such changes. Organ capillary blood flow and the fractional distribution of cardiac output were measured by the microsphere (9-microns diameter) trapping method in dogs. Simultaneously, the arteriolovenous shunt rate was measured by continuous collection of venous blood drained at 4.8 ml.min-1 for 2 min from the brain, kidney, liver, splanchnic organs, skeletal muscle of the pelvic limb, and all of the systemic circulatory organs. The capillary blood flow of the brain, thyroid gland, pancreas, and stomach decreased after circulatory arrest in five nonhemodiluted dogs (group C); arteriolovenous shunt rate was unchanged after circulatory arrest in this group. However, with hemodilution, which was induced either before (pre group, n = 5) or after (post group, n = 5) circulatory arrest, no change occurred in the shunt rate in any of the organs, with the exception of an increase in the systemic arteriolovenous shunt rate in the pre group. Capillary blood flow was maintained at almost the same level as before circulatory arrest in the pre group, but increased significantly in several organs of the post group. The data indicated that hemodilution might be effective for prevention of organ ischemia after cardiac arrest.

Animals↗
PubMed1990

[Measurement of airway resistance by an interrupter technique in anesthetized dogs during methacholine induced bronchoconstriction].

Airway resistance was measured by an interrupter technique in anesthetized and paralyzed dogs. Bronchoconstriction was then induced by the inhalation of methacholine hydrochloride at a concentration of 25 or 50 mg . ml-1 for ten minutes. Airway resistance was measured again immediately after the inhalation of methacholine and 50 minutes later. Under normal conditions, airway resistance increased with a linear relationship to the expiratory airflow as expressed by a function of Y = K1 + K2X. K1 and K2 were calculated by a least square method. As a result, K1 increased markedly immediately after the inhalation of methacholine and returned to the control level thereafter. However, it was still higher than the control 50 minutes later. On the other hand, no statistically significant changes were observed because the changes in K2 were variable. In some cases, K2 increased, while in others it was unchanged. K2 decreased in more cases, however, and a negative value was often seen. This inverse correlation between flow and resistance was supposed to reflect the occurrence of small airway obstructions during the end expiratory phase. Therefore, it was considered that this method is capable of detecting small airway abnormalities which could not be detected by %FEV1.0.

Airway Resistance↗
PubMed1989

Effects of hypocapnia and hypercapnia on splanchnic circulation and hepatic function in the beagle.

The effects of mild hypocapnia (PaCO2 22 mm Hg) and hypercapnia (PaCO2 59 mm Hg) on the splanchnic circulation and hepatic function were studied in six pentobarbital anesthetized, laparotomized, mechanically ventilated beagles. Tidal volume and respiratory frequency were held constant throughout the measurements. Hepatic artery blood flow (HABF) and portal vein blood flow (PVBF) were measured by electromagnetic flowmeters. Hepatic function was assessed by indocyanine green (ICG) elimination kinetic analysis after intravenous injection of the dye. Hypocapnia caused a decrease in HABF without affecting the systemic circulation. Hypercapnia, on the other hand, caused a significant increase in cardiac output without changing mean arterial pressure. There was a significant increase in PVBF and total hepatic blood flow (THBF = PVBF + HABF). Despite the increases in PVBF and THBF, the half-life of ICG was significantly longer during hypercapnia (9.09 +/- 0.79 min) than during hypocapnia (7.16 +/- 0.37 min), and plasma ICG clearance was smaller during hypercapnia (4.79 +/- 0.44 ml.min-1) than during hypocapnia (5.44 +/- 0.33 ml.min-1) or normocapnia (5.27 +/- 0.50 ml.min-1), indicating the depressed hepatic function during hypercapnia. We conclude that mild hypocapnia decreases HABF without affecting hepatic function and that mild hypercapnia is associated with a depression of hepatic function in spite of the increases in PVBF and THBF.

Animals↗
PubMed1989

[The effect of IPPV, with or without PEEP, on central venous pressure].

Changes in central venous pressure (CVP) during intermittent positive pressure ventilation with a Bennett 7200 respirator were measured in 30 postoperative patients without hemodynamic abnormalities. The tidal volume was changed from 300 ml to 900 ml and the PEEP was changed from 0 cmH2O to 8 cmH2O, step by step, respectively. Mean airway pressure (Pmean), maximal airway pressure (Pmax), arterial blood pressure, and heart rate were measured simultaneously with the measurement of CVP. CVP increased linearly with increases in the tidal volume and PEEP. A linear correlation was seen between Pmean and CVP. The value of A was 7.5 +/- 6.2 cmH2O and that of B was 0.32 +/- 0.13 when the equation of the regression line was Y = A + BX, where X was Pmean and Y was CVP. The coefficient of correlation was 0.88 +/- 0.09 (n = 30, P less than 0.01). The value of CVP during intermittent positive pressure ventilation increased linearly at rate which was 32% of the increase in Pmean. The value of CVP was considered to be 7.5 +/- 6.2 cmH2O when Pmean was zero. There was no change in the arterial blood pressure and heart rate throughout the measurement. This suggests that increases in CVP might not reflect any accompanying hemodynamic change.

Central Venous Pressure↗