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Biomedical subjects

K Irita

Publications and source records attributed to K Irita.

At least 37 records · Page 2Linked to original sources
PubMed1999

Detection of retroperitoneal hemorrhage by transesophageal echocardiography during cardiac surgery.

PURPOSE: To present a case of massive retroperitoneal hemorrhage during cardiopulmonary bypass (CPB) which was detected using transesophageal echocardiography (TEE). CLINICAL FEATURE: A 50-yr-old man suffering from severe mitral regurgitation (MR) was admitted for mitral valvuloplasty. After the beginning of CPB, the volume in the reservoir was noticed to be gradually decreasing. Although venous cannulation had been properly performed, TEE showed an echo free space around the liver, the spleen and in front of the abdominal aorta showed intraabdominal hemorrhage. After cardiac surgery, emergency laparotomy revealed about 5,000 ml of blood in the retroperitoneal space probably as a result of femoral artery cannulation prior to CPB. Hemostasis was achieved, and the patient made complete cardiac and neurological recovery. Retrospective review of the TEE imaging revealed that the kidneys were surrounded by blood bilaterally confirming the diagnosis of retroperitoneal hemorrhage. CONCLUSION: Retroperitoneal hemorrhage during CPB is rare, but may be lethal. Transesophageal echocardiography is a useful monitor not only to evaluate cardiac performance, but also to detect unexpected intraabdominal bleeding during cardiac surgery.

Abdomen↗
PubMed1999

Dibucaine and tetracaine inhibit the activation of mitogen-activated protein kinase mediated by L-type calcium channels in PC12 cells.

BACKGROUND: An elevation of the intracellular calcium level, which is mediated by N-methyl-D-aspartate receptors and L-type Ca2+ channels both, activates the mitogen-activated protein (MAP) kinase signaling pathway involved in synaptic modification. It has recently been suggested that MAP kinase plays a role in coupling the synaptic excitation to gene expression in the nucleus of postsynaptic neurons. Because the effects of local anesthetics on cellular signal transduction in neuronal cells are not well-known, the authors investigated whether they affect the MAP kinase signaling pathway using PC12 cells. METHODS: The cells were stimulated with either 50 mM KCl or 1 microM ionomycin, and activated MAP kinase was thus immunoprecipitated. The immunocomplexes were then subjected to an Elk1 phosphorylation assay. Both the phosphorylation of MAP kinase and the induction of c-Fos were detected by immunoblotting. RESULTS: Pretreatment of the cells with 1 mM (ethylenedioxy)-diethyl-enedinitrilotetraacetic acid or 5 micron nifedipine blocked the MAP kinase activation induced by 50 mM KCl, whereas pretreatment with 2 microM omega-conotoxin GIVA did not. The expression of c-Fos induced by potassium chloride was also suppressed by dibucaine, tetracaine (concentrations that inhibited 50% of the activity of positive control [IC50s] were 16.2+/-0.2 and 73.2+/-0.7 microM, respectively), and PD 98059, a mitogen-activated/extracellular receptor-regulated kinase inhibitor. Higher concentrations of dibucaine and tetracaine were needed to suppress the activation of MAP kinase induced by ionomycin (the IC50 values of dibucaine and tetracaine were 62.5+/-2.2 and 330.5+/-32.8 microM, respectively) compared with potassium chloride (the IC50 values of dibucaine and tetracaine were 17.7+/-1.0 and 70.2+/-1.2 microM, respectively). Although probable targets of these local anesthetics might be L-type Ca2+ channels or components between Ca2+ and Ras in MAP kinase pathway, the possibility that they directly affect MAP kinase still remains. CONCLUSIONS: Dibucaine and tetracaine at clinical concentrations were found to inhibit the activation of MAP kinase and the expression of c-Fos mediated by L-type Ca2+ channels in PC12 cells. The suppression of MAP kinase pathway may thus be a potential target site for the actions of dibucaine and tetracaine, including the modification of the synaptic functions.

Anesthetics, Local↗
PubMed1999

Impaired oxygen utilization during rapid cooling on cardiopulmonary bypass.

UNLABELLED: Little attention has been paid to oxygen demand/supply balance during the cooling phase of cardiopulmonary bypass (CPB). We examined the changes in systemic oxygen utilization caused by the initiation of deep hypothermic CPB. METHODS: We calculated the changes in systemic oxygen consumption (VO2) and its related parameters in 5 patients who underwent reconstruction of the aortic arch using deep hypothermic CPB. Rectal temperature was decreased to 18 centigrade on average. RESULTS: VO2 decreased immediately after the initiation of hypothermic CPB. VO2 decreased by an average of 50% and 64%, while rectal temperatures decreased from 35 to 34 and 32 centigrade, respectively. Hemoglobin-bound oxygen accounted for 68% of VO2 just before CPB and 28% after the rectal temperature decreased to 32 centigrade. This decrease in VO2 correlated with the maximum temperature gradient between the venous and the arterial blood during the cooling phase. The abrupt decrease in VO2 by initiating CPB was associated with an increase in mixed venous oxygen saturation and a decrease in oxygen extraction ratio. VO2 values during the cooling phase were much lower than those during the rewarming phase at any given rectal temperatures. VO2 values at rectal temperatures of 34 and 32 centigrade during the cooling phase of CPB were 40% and 29% of those during the rewarming phase of CPB, respectively. This difference was caused by the changes in VO2 derived from hemoglobin-bound oxygen, and VO2 derived from dissolved oxygen did not show any significant changes during the cooling and the rewarming phase. Hysteresis of VO2 was also observed as a function of the nasopharyngeal temperature. The arterial lactate concentration showed an insignificant but gradual increase during the cooling phase. CONCLUSION: These observations suggested that an immediate decrease in VO2 and the following low values of VO2 caused by the initiation of deep hypothermic CPB could not be simply due to a decrease in the metabolic rate for oxygen but rather due to disturbances in oxygen utilization, one of which seemed to be caused by the impaired oxygen release from hemoglobin. It was also suggested that an increase in mixed venous oxygen saturation by initiating hypothermic CPB did not necessarily indicate an adequate oxygen/demand supply balance.

Adult↗
PubMed1998

A possible increase in plasma norepinephrine by removal of the liver.

BACKGROUND: It has recently been suggested that the human liver plays an important role in clearing plasma norepinephrine, especially in restricting most of the norepinephrine to reach the systemic circulation from the gut. METHODS: We examined the changes in plasma catecholamine levels in a patient undergoing extracorporeal hepatic resection and 4 patients undergoing living-related orthotopic liver transplantation. RESULTS: While the changes in plasma epinephrine levels were not necessarily consistent with the proposal that plasma catecholamine levels increase during the anhepatic period, plasma norepinephrine did show a transient increase in accordance with the anhepatic period in all cases. Although we could not rule out the increase in the inflow rate of norepinephrine into plasma, the interrupted hepatic elimination of norepinephrine, especially released from the gut, seemed to be partly responsible for the anhepatic period-associated increase in plasma norepinephrine. CONCLUSION: The present finding might have the potential to improve perioperative management of patients undergoing extracorporeal hepatic resection and orthotopic liver transplantation.

Adrenergic Agonists↗
PubMed1997

Anesthetic management of children with moyamoya disease.

A review of the surgical and postoperative records of 127 revascularization procedures performed on 82 children with Moyamoya disease was done to evaluate changes we made in anesthetic management in response to perioperative complications. From 1982 to 1996, out of 82 children who underwent revascularization surgery at our hospital, five developed perioperative complications. One developed circulatory instability during surgery; the cause seemed to be a depth of anesthesia insufficient for preventing surgical stress. To rectify this problem, an increased dose of fentanyl was used to improve the maintenance of anesthesia. Four patients developed cerebral infarction during the early postoperative period due, in part, to inadequate management of postoperative pain. We began to administer supplemental doses of meperidine to patients after they emerged from anesthesia to provide better control of postoperative pain. Our review confirmed the effectiveness of these measures. The data suggest that during the perioperative management of children with Moyamoya disease, close attention should be paid to balancing the patients' anesthetic state against surgical stress and providing adequate postoperative analgesia.

Analgesics, Opioid↗
PubMed1997

Capnometry as a tool to unmask silent pulmonary embolism.

Because pulmonary embolism is often silent, simple clinical procedures are desirable to identify patients with a low to intermediate probability of pulmonary embolism. Among 19,467 patients managed under general anesthesia, we had one bile tract surgery case and three neurosurgical cases whose silent pulmonary embolism was initially suggested by an increase in the arterial to end-tidal CO2 gradient (from 17 to 27 mmHg) after general anesthesia was induced or their trachea was intubated. During the preoperative assessment, the patients presented no clinical manifestations suggestive of pulmonary embolism. Our initial diagnosis was confirmed by scintigraphy and/or angiography done immediately after the operations. Because capnometry has been shown to be applicable to non-intubated, spontaneously breathing patients, we suggest that measuring the gradient may serve as an additional method for unmasking silent pulmonary embolism in patients at risk or with disturbed consciousness, whether they are scheduled for operations or not.

Aged↗
PubMed1997

[Safe levels of hemoglobin concentration in autologous blood transfusion].

It has been generally accepted that an adequate oxygen-carrying capacity can be achieved with a hemoglobin concentration of 7 g/dl, as far as the patient's intravascular volume is sufficient to allow tissue perfusion. To guarantee patient's safety in the operating theater, patient's oxygenation, ventilation, circulation and temperature, which enable oxygen utilization in tissues, should be monitored vigilantly and ensured strictly. This is also true when taking care of anemic patients outside the operating theater, because failure of these functions in anemic patients leads directly to tissue hypoxia. Besides the standard monitoring, measuring oxygen carrying capacity/consumption parameters and gastric/sigmoidal intramucosal pH have been shown to be helpful to estimate tissue oxygenation. Therefore, safe levels of hemoglobin concentration should be determined according to the ability of doctors and nursing staffs to evaluate and to maintain patient's systemic and tissue oxygenation as well as to the patient's pathophysiological conditions.

Anemia↗
PubMed1996

Potentiation of carbon tetrachloride-induced liver damage by dibutylyl-3',5'-cyclic AMP in unstarved rats.

It has been reported that carbon tetrachloride-induced liver damage is potentiated by starvation partly due to fat accumulation in the liver and a decrease in hepatic reduced glutathione concentration and that dibutylyl-3',5'-cyclic AMP (DBcAMP) affects fuel metabolism and decreases hepatic reduced glutathione. We investigated the effects of DBcAMP on carbon tetrachloride-induced liver damage both in unstarved and starved rats. In unstarved rats, intraperitoneal administration of DBcAMP potentiated an increase in serum alanine aminotransferase activity and fatty vacuolization in the liver, both of which were induced by carbon tetrachloride. Hepatic reduced glutathione concentration was also reduced by DBcAMP, although the change was not significant. In contrast, the administration of DBcAMP in starved rats did not affect carbon tetrachloride-induced changes in serum alanine aminotransferase activity, histological alterations and hepatic reduced glutathione concentration. Administration of DBcAMP to control rats induced different responses in unstarved control rats compared with starved control rats: in unstarved rats, blood glucose concentration decreased but serum free fatty acid concentration increased, whereas in starved rats, blood glucose concentration increased and serum free fatty acid concentration decreased. It was suggested that DBcAMP potentiated carbon tetrachloride-induced liver damage in unstarved rats, probably due to hepatic fat accumulation and a decreased hepatic reduced glutathione concentration. The former could increase the affinity of the liver for carbon tetrachloride and the latter could accelerate carbon tetrachloride-induced lipid peroxidation. It was also suggested that DBcAMP failed to affect carbon tetrachloride-induced liver damage in starved rats, probably because starvation had already decreased hepatic glutathione concentration and DBcAMP had different effects on fuel metabolism compared with effects observed in unstarved rats.

Alanine Transaminase↗
PubMed1996

Effects of OP 2507, a stable analogue of prostaglandin I2, on carbon tetrachloride-induced liver damage in starved rats.

It has been reported that vasodilatory prostaglandins have cytoprotective effects against various types of liver damage. We investigated the effects OP 2507, a stable analogue of prostaglandin I2, on carbon tetrachloride-induced liver damage in starved rats. Intraperitoneal administration of OP 2507 at 1,500 micrograms/kg lessened both an increase in serum alanine aminotransferase activity and an inhibition of starvation ketosis, both of which were induced by carbon tetrachloride. At lower doses, however, OP 2507 not only failed to ameliorate the carbon tetrachloride-induced changes, but it actually exaggerated them. Although the deterioration of carbon tetrachloride-induced liver damage by lower doses of OP 2507 was not statistically significant, it seems possible that OP 2507 has dual effects on carbon tetrachloride-induced liver damage. While none of the three agents cimetidine, reduced glutathione and deferoxamine, prevented increase in serum alanine aminotransferase activity induced with lower dose OP 2507, allopurinol had a tendency to prevent the increase, indicating that lower doses of OP 2507 may promote a reaction catalyzed by xanthine oxidase. We propose that both the co-administration of prostaglandins and other potentially hepatotoxic drugs, and the administration of prostaglandins to patients with drug-induced liver damage should be done carefully.

Alanine Transaminase↗
PubMed1996

The difference between the changes in systemic oxygen consumption during orthotopic liver transplantation and those during extracorporeal hepatic resection.

Every organ in the body requires oxygen to perform its function. In liver transplantation and extracorporeal hepatic resection, oxygen utilization by the graft or the re-implanted liver is a prerequisite for restoration of liver function. We compared the changes in systemic oxygen consumption in a patient who underwent orthotopic liver transplantation with those in two patients who underwent extracorporeal hepatic resection. The pre-anhepatic systemic oxygen consumption in the patient who underwent orthotopic liver transplantation seemed to be lower than that in the patients who underwent extracorporeal hepatic resection, possibly due to the depressed oxygen utilization which sometimes occurs in cirrhotic patients. The increase in oxygen consumption or the overconsumption of oxygen after reperfusion was more significant in the patient who underwent orthotopic liver transplantation than in the patients who underwent extracorporeal hepatic resection. The possible causes might be the greater hepatic oxygen debt, an associated intestinal oxygen debt, and/or the greater ischemia/reperfusion-induced overproduction of superoxide anion in the patient who underwent orthotopic liver transplantation. The differences between the changes in systemic oxygen consumption during orthotopic liver transplantation and those during extracorporeal hepatic resection further support the usefulness of systemic oxygen consumption to predict the immediate restoration of blood flow and oxygen utilization in the graft or the re-implanted liver. These findings also support the importance of evaluating oxygen consumption to confirm whether the critically ill or unconscious patient can utilize oxygen on demand or not.

Female↗
PubMed1995

[Mycoplasma pneumonia found by the occurrence of atelectasis during the induction of anesthesia in a child with tetralogy of Fallot].

A 3-yr-old girl was scheduled to undergo surgical repair of tetralogy of Fallot. She had no sign or data indicating an infectious disease, other than a slight dry cough for a few days prior to the proposed operation. During the induction of anesthesia with nitrous oxide, oxygen and sevoflurane, transient moist rale was noticed with a precordial stethoscope. Her trachea was intubated without any difficulty after the administration of pancuronium, followed by a chest auscultation, which revealed vesicular sound bilaterally but no rale. However, a chest X-ray taken after the right subclavian vein catheterization showed a massive hypoaeration in the upper left pulmonary region. The presence of the right-to-left intracardiac shunt made it impossible to detect the occurrence of atelectasis by a decrease in SpO2. Fiberoptic bronchoscopy showed no obstruction of the bronchus and no hypersecretion initially, but physical therapy and humidification made it possible to aspirate intratracheal sputum. Because there seemed to be an imbalance between the relatively uneventful induction of anesthesia and the relative resistance of atelectasis to authentic therapies, the operation was postponed, and the antibody to mycoplasma pneumoniae was titrated. The titer in the serum was 1:80, and increased to 1:560 6 days later. Chest X-rays revealed normal lung condition 3 days later, and she was given erythromycin, 800 mg.day-1 for 2 weeks. We conclude that we should be alert to possible asymptomatic mycoplasma infection, which potentially makes patients susceptible to atelectasis during the perioperative period.

Anesthesia, Inhalation↗