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Biomedical subjects

J Yoshitake

Publications and source records attributed to J Yoshitake.

At least 55 records · Page 3Linked to original sources
PubMed1990

[Blood gas disorders during one lung ventilation and the efficacy of the monitors].

The incidence and the causes of the abnormal blood gas levels were analysed with 188 patients who had one lung ventilation during general anesthesia, and the monitors to detect such complications were discussed. Abnormal blood gas levels were detected in 47 patients (25%), and 6 of 47 patients had dislocation of endotracheal tube or cuff. There was one patient who suffered from severe blood gas disorder due to the total occlusion of trachea by cuff herniation. Forty one cases (41.8%) had abnormal blood gas levels even though there was no dislocation of endotracheal tube or cuff. In these patients the blood gas abnormalities were mild and transient. These data suggest that mild blood gas disorders were relatively easily detected with pulse oximeters and capnography. However, serious disorders were not detected with these monitors if the anesthesiologists were not familiar with these equipment.

Adolescent↗
PubMed1989

Protein kinase C and simulated ischemia possible aberrations of signal transduction during ischemia.

ATP depletion is always associated with prolonged ischemia. It was found that ATP affected calcium- and phospholipid-dependent activation of protein kinase C without hydrolysis of the nucleotide when the activation was monitored by an assay for [3H] 4-beta-phorbol-12, 13-dibutyrate binding activity in a reconstitution system having physiological concentrations of free calcium. When the ATP level was low, an increase in the free calcium concentration could not activate the enzyme. A decrease in pH exacerbated the depressed activation. The concentration of magnesium also affected the activation. On the other hand, free fatty acids, which increase during ischemia, were able to activate the enzyme at a low concentration of ATP in the absence of phorbol ester and phosphatidylserine. These results suggest that calcium- and phospholipid-dependent activation of protein kinase C is suppressed during ischemia, and that fatty acids in turn activate the enzyme. It is possible that ischemia interferes with normal signal transduction via the protein kinase C pathway and causes unusual protein phosphorylation.

Journal Article↗
PubMed1989

The hemodynamic and metabolic changes in prostaglandin E1-induced hypotension in dogs--a comparative study with trimetaphan-induced hypotension.

The hemodynamic and metabolic changes in hypotensive state induced with prostaglandin E1 (PGE1) or trimetaphan (TMT) infusion were investigated in dogs. Mean arterial pressure was decreased by about 50% with 1.58 microg/kg/min of PGE1 or 45 microg/kg/min of TMT. Heart rate, pulmonary capillary wedge pressure and central venous pressure remained virtually unchanged in the two groups. Cardiac output was well maintained in PGE1 group, whereas cardiac output showed the tendency to decline in TMT group. Greater reduction in systemic vascular resistance was seen in PGE1 group than in TMT group. Pulmonary vascular resistance showed no significant change in PGE1 group, whereas it increased significantly in TMT group. Gradual decreases in arterial pH, PaO2 and base excess and slight but significant increase in PaCO2 was observed in PGE1 group, and these abnormalities recovered 30 min after hypotension. Abnormalities in blood gases and acid-base balance were considerably more severe and prolonged in TMT group compared with those in PGE1 group. Blood lactate and pyruvate concentrations showed no significant changes in PGE1 group, whereas substantial elevation was seen in L/P ratio especially 30 min after induction of hypotension in TMT group. Oxygen consumption showed minimal changes in PGE1 group, whereas a significant decrease was observed in TMT group. The conclusions derived from these results are as follows; 1) PGE1 maintained cardiac output better than TMT, probably because of its direct inotropic action on the heart, and of its greater reduction of systemic vascular resistance than TMT. 2) PGE1 seemed to provide the better blood perfusion throughout the body than TMT. 3) PGE1 showed less possibility to produce the metabolic derangement compared with TMT.

Journal Article↗
PubMed1989

Induced hypotension for surgical repair of congenital dislocation of the hip in children.

The surgical repair of congenital dislocation of the hip was performed under normotensive anaesthesia (23 children) and hypotensive anaesthesia (52 children). Hypotension was induced with infusion of hypotensive agents such as trimetaphan or nitroglycerin during inhalation or neurolept-anaesthesia under careful monitoring of blood pressure, haematocrit and electrocardiogram. Blood replacement was done to keep hematocrit value above 30%. Blood loss was significantly less in hypotensive group (2.53 ml/kg/h) than that in normotensive group (4.53 ml/kg/h). Twenty one percent of patients in hypotensive group required blood transfusion with the rate of 3.3 ml/kg/h compared with 43% of cases in normotensive group with the rate of 4.4 ml/kg/h. Depending upon anaesthesia technique blood loss was greater in neuroleptanaesthesia (5.5 ml/kg/h) than inhalation (2.3 ml/kg/h) or epidural (2.1 ml/kg/h) anaesthesia. Urine output and laboratory data for liver and kidney functions were not different between normotensive and hypotensive group. The dose of hypotensive agents required to produce moderate hypotension for paediatric patients was much higher than that for adult. We consider that moderate hypotension is safe procedure if employed by well experienced anaesthetist with careful monitoring of blood pressure, Hct and ECG. Blood loss and requirement of blood replacement are significantly reduced with this technique.

Journal Article↗
PubMed1989

Ketamine-induced relaxation in intact and skinned smooth muscles of the rabbit ear artery.

1. The effects of ketamine, an intravenous anaesthetic, on the rabbit ear artery were investigated by measuring the tension in intact and saponin-treated skinned smooth-muscle fibres. 2. Ketamine dose-dependently inhibited contractions of intact smooth-muscle fibres induced by high K+ solution and by noradrenaline (NA) or histamine in Krebs solution. This drug similarly attenuated both phasic and tonic contractions induced by high K+ solution. 3. Ketamine also inhibited NA- or histamine-induced contractions in Ca2+-free solution containing 2mM EGTA, but it did not affect the caffeine-induced contraction in this solution. 4. Because the pCa-tension relationship of saponin-treated skinned smooth-muscle fibres was not affected, it can be proposed that ketamine does not have an effect on the contractile proteins. 5. In the presence of 5mM NaN3, 20 microM inositol 1,4,5-trisphosphate (InsP3) or 25mM caffeine produced a contraction in skinned smooth-muscle fibres after accumulation of Ca2+ by intracellular stores. Analysis of the InsP3- or caffeine-induced contractions indicates that ketamine does not have an effect on the Ca2+ accumulation into and Ca2+ release from the intracellular stores. 6. These results indicate that the relaxant effects produced by ketamine in the rabbit ear artery are not likely to be due to an intracellular action. The inhibitory effects of ketamine could be caused by a decrease of the Ca2+ influx through the plasma membrane or interference with the process of signal transduction between receptors on the plasma membrane and intracellular stores.

Animals↗
PubMed1989

[Dose requirement for caudal anesthesia in pediatric patient].

A series of 305 infants and children between 1 day to 14 years of age were operated upon using caudal anesthesia. We used 1% mepivacaine 1.2 ml.kg-1 to obtain a level of anesthesia above T10, 1.0 ml.kg-1 above L1, and 0.8 ml.kg-1 above S. Complete failure occurred in 4.3% of patients. We investigated the blood concentration of mepivacaine in 17 patients, and it ranged from 0.5 microgram.ml-1 to 5.0 micrograms.ml-1. In a two month old infant, weighing 6.7 kg, apnea and bradycardia occurred. This was managed by tracheal intubation and controlled ventilation. But there were no other severe complications. We also investigated the distance between C7 and sacral hiatus (D) in each case. The coefficients of correlation between D and height is 0.97, and high correlation existed also between D and body weight (r = 0.93). This confirms that body weight can be used as a parameter to determine the dose of local anesthetic agent. We conclude that this technique is a safe, reliable and simple way to produce surgical analgesia in infants and children.

Adolescent↗
PubMed1988

Increased release of alpha-atrial natriuretic peptide during controlled mechanical ventilation with positive end-expiratory pressure in humans.

The objective of this study was to test the hypothesis that a release of alpha-artrial natriuretic peptide (ANP) is depressed resulting in the reduction of urinary output in patients receiving controlled mechanical ventilation (CMV) with positive end-expiratory pressure (PEEP). Five normovolemic patients with no apparent cardiac, renal, endocrine, or pulmonary dysfunctions were included in this study. After the patients were mechanically ventilated using a volume-cycled ventilator with zero cmH(2)O PEEP for one hour, hemodynamic variables were measured. Urine and blood samples were collected after the measurements. Plasma alpha-ANP levels were determined on blood samples taken from radial artery using specific radioimmunoassay. Then PEEP levels were changed to 5, 10, 15 and, finally, 0 cmH(2)O in four consecutive one-hour periods. At the end of each period, the measurements and collection of the samples were repeated. With increasing levels of PEEP, central venous pressure (CVP), pulmonary artery wedge pressure (PAWP), and heart rate were pressure-dependently increased. On the other hand, cardiac output and urinary output were decreased. Plasma levels of alpha-ANP were also increased by the institution of PEEP. These changes occurred in a pressure-dependent fashion. Urinary sodium excretion, potassium excretion, fractional excretion of sodium and free water clearance remained unchanged. It is concluded that a release of alpha-ANP was augmented rather than depressed with PEEP. This suggests that a decrease in urinary excretion in patients with PEEP may not be due to a reduced release of alpha-ANP.

Journal Article↗
PubMed1988

Preservation of baroreflex control of vascular resistance under ketamine anesthesia in rats.

The aim of this study was to examine the effects of ketamine and pentobarbital on the baroreceptor reflex control of vascular resistance in rats. The gains of baroreflex were assessed by relating changes in arterial pressure to changes in hindlimb perfusion pressure, using an extracorporeal perfusion circuit with a delay system. Reflex-induced vasodilation or vasoconstriction in response to a rise or a fall in arterial pressure were elicited by injections of phenylephrine or nitroprusside, respectively. The gains of baroreflex were not altered by ketamine 1 and 5 mg/kg (i.v.), whereas those were depressed by pentobarbital 5 mg/kg (i.v.). The results suggest that ketamine preserves the baroreflex control of vascular resistance and pentobarbital depresses it. The preservation of the baroreflex control of vascular resistance may be advantageous for patients with hypovolemia to sustain the blood pressure.

Journal Article↗
PubMed1987

Contribution of arterial redox potential measurement to the care of critically ill patients.

175 arterial and 122 urinary samples from 20 patients admitted in ICU for organ system failure (OSF) were analysed. Besides arterial blood gases and lactate, electrolyte concentrations, pH, rH2 and specific resistance (R) in blood and urine were measured. Redox potential (E) and base excess were calculated from these data. Patients were defined as having MOSF if their organ systems met failure criteria during their ICU stay. Data were classified with corresponding number of OSF developed in the patients when samples were obtained. Acid-base balance or base excess alone could not be used to predict the severity of illness as assessed by increasing number of organ system failures. Significant elevations in blood lactate concentrations were observed only in patients with four, five or six OSF. A lack of correlation between blood lactate and severity of OSF indicates that blood lactate is not valid as a guide to ultimate outcome of the patients. Arterial redox potentials progressively decreased with increasing number of OSF, therefore, it can be stated that the serial measurements of arterial redox potential are useful in assessing the patient's status or predicting their ultimate outcome.

Journal Article↗
PubMed1987

Venodilator effects of adenosine triphosphate and sodium nitroprusside; comparisons during controlled hypotension.

Adenosine triphosphate as well as sodium nitroprusside has been used for hypotensive anesthesia. The purpose of this study was to examine the possibility that two hypotensive drugs may exert different effects on venous capacitance during controlled hypotension. In rats anesthetized with ketamine, mean arterial pressure was lowered to 50 mmHg by intravenous infusion of adenosine triphosphate or sodium nitroprusside. Venous capacitance was assessed before and during induced hypotension by measuring the mean circulatory filling pressure (MCFP). MCFP was measured after briefly arresting the circulation by inflating an indwelling balloon in the right atrium. MCFP was lower during adenosine triphosphate-induced as well as sodium nitroprusside-induced hypotension as compared with the respective value at control (P < 0.01 for adenosine triphosphate and sodium nitroprusside). However, the decrease in MCFP by adenosine triphosphate (0.8 +/- 0.1 mmHg) was less (P < 0.01) than that by sodium nitroprusside (2.3 +/- 0.3 mmHg). These results suggest that at a comparable level of arterial hypotension venodilator effect of adenosine triphosphate was less than that of sodium nitroprusside. Less venodilatation during adenosine triphosphate-induced hypotension may contribute to the maintenance of cardiac output during hypotensive anesthesia.

Journal Article↗
PubMed1987

Inhibition of leukotriene formation in human leukocytes by halothane.

The effects of an inhalation anesthetic, halothane (2-bromo-2-chloro-1,1,1-trifluoroethane) on the formation of 5-lipoxygenase metabolites such as leukotriene B4, 5(S)-hydroxyeicosatetraenoic acid (5-HETE), 6-trans-isomers of leukotriene B4 and leukotriene C4 were studied in human leukocytes stimulated with calcium ionophore A23187. Halothane inhibited the formation of all these metabolites dose dependently and the formation was restored by removal of the drug. The anesthetic also reversibly inhibited the release of [3H]arachidonic acid from neutrophils with a half-inhibition concentration of less than 0.19 mM. The formation of 5-lipoxygenase metabolites was not inhibited by the anesthetic when leukocytes were stimulated with the ionophore in the presence of exogenous arachidonic acid. These observations indicate that the inhibitory effect of halothane on the formation of 5-lipoxygenase metabolites in leukocytes is mainly due to the inhibition of arachidonic acid release.

Arachidonate 5-Lipoxygenase↗
PubMed1987

The bioelectronic factors of human body fluids and intravenous replacement solutions.

In this paper the analytical method of the pH, rH2 and specific resistance of body fluids with B.E.-VINCENT Unit was described. From the values of the pH, rH2 and specific resistance, other three bioelectronic factors, the redox potential, milliampere and micro-watts, were calculated. With this technique the bioelectronic factors of arterial and venous blood and urine obtained from 20 young healthy adults were examined. Those of arterial and venous blood showed almost identical values. The urinary values of the pH, milliampere and microwatts varied as compared to those of blood. The bioelectronic factors of the various intravenous replacement solutions and blood components were considerably different from those of blood. It is considered that the bioelectronic factors of patient's blood should be checked repeatedly and maintained in an appropriate state when massive fluid therapy is required.

Journal Article↗