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Biomedical subjects

M Kuro

Publications and source records attributed to M Kuro.

At least 19 recordsLinked to original sources
PubMed1992

Selective beta 1 and beta 2 adrenoceptor blockade on epinephrine-induced arrhythmias in halothane anaesthetized dogs.

Beta 2 as well as beta 1 adrenoceptors have been recognized in the heart of vertebrates. They mediate a positive chronotropic action of catecholamines. We compared the effect of selective beta 1 and beta 2 adrenoceptor antagonists on the genesis of halothane-epinephrine arrhythmias in dogs. The arrhythmogenic dose (AD) of epinephrine was increased in the presence of l-metoprolol, a selective beta 1 antagonist (8.40 +/- 1.13 micrograms.kg-1 x min-1; mean +/- SEM), compared with control value (2.62 +/- 0.56) (P < 0.05). In contrast, ICI-118,551, a selective beta 2 antagonist, did not change the AD (2.36 +/- 0.43). Adding ICI-118,551 to l-metoprolol did not affect the AD of epinephrine in the presence of l-metoprolol alone (6.34 +/- 0.74 vs 8.40 +/- 1.13). These results suggest that selective beta 1 blockade is effective in preventing halothane-epinephrine arrhythmias, but selective beta 2 blockade is not.

Adrenergic beta-Antagonists↗
PubMed1992

Clinical evaluation of cerebral oxygen balance during cardiopulmonary bypass: on-line continuous monitoring of jugular venous oxyhemoglobin saturation.

To prevent brain damage during cardiopulmonary bypass (CPB), adequate cerebral perfusion for cerebral oxygen demand should be maintained. We monitored jugular venous oxyhemoglobin saturation (SjO2), which reflects the overall balance of cerebral oxygen supply and demand, continuously in 12 patients undergoing cardiac surgery. We examined whether this balance is disrupted during CPB, and if so, analyzed critical factors that affect this phenomenon. At the initiation of CPB, in spite of a significant decrease in mean arterial pressure, SjO2 did not change, and it was stable during the hypothermic period of CPB. On the other hand, a significant reduction in SjO2 was observed during the rewarming period, and SjO2 had an inverse linear correlation with nasopharyngeal temperature. Furthermore, the percent decrease of SjO2 was significantly related to "rewarming speed" (an average increase in temperature per minute). Our results indicate that temperature change during the rewarming period is a critical factor affecting the balance of cerebral oxygen supply and demand during CPB.

Adult↗
PubMed1992

Internal jugular vein catheterization in infants undergoing cardiovascular surgery: an analysis of the factors influencing successful catheterization.

Central venous catheterization for pressure monitoring and drug administration is often important in the anesthetic management of infants undergoing cardiovascular surgery. We examined the effects of patient age, weight, and central venous pressure and the experience of the anesthesiologist on the rate of successful catheterization and catheterization time of the internal jugular vein (IJV) in a prospective study. We studied 106 infants undergoing IJV catheterization for cardiovascular surgery over a 7-mo period at our institution. We catheterized the IJV by the high approach. The direct venipuncture or the Seldinger method was used according to the patient's weight. Overall successful catheterization rate was 97.2%, and the average catheterization time was 353 +/- 21 s (mean +/- SEM). Complications included arterial puncture in 12 cases (11.3%), hematoma formation in four cases (3.8%), and catheter malposition in two cases (1.9%), but pneumothorax was not observed. When a patient was younger than 3 mo or weighed less than 4.0 kg, successful catheterization rate decreased significantly to 81.3% and 78.6%, respectively. Catheterization time was inversely correlated with both age and weight, whereas central venous pressure did not affect either successful catheterization rate or catheterization time. We were unable to demonstrate that the experience of the anesthesiologist plays a significant role in the success or complication of the catheterization procedure. Our results indicate that IJV catheterization by the high approach is a reliable and useful technique in infants, and that the weight and age of the patient significantly influence the rate of successful catheterization.

Age Factors↗
PubMed1992

[Effects of hypothermia with cardiopulmonary bypass on posterior tibial nerve somatosensory evoked potentials in man].

Somatosensory evoked potential after posterior tibial nerve stimulation (PTN-SEP), as well as nasopharyngeal, bladder and plantar temperature were recorded in ten patients during cardiac surgery with hypothermic cardiopulmonary bypass. There was a best negative correlation between latencies (P27, P40 and the interpeak latency between P40 and P27 (P40-P27)) and nasopharyngeal temperature, but no correlation was found between latencies and plantar temperature during cooling and rewarming (27-37 degrees C) with cardiopulmonary bypass. No correlation was found between changes in amplitude and temperature. The slope of linear regression line of latencies versus nasopharyngeal temperature was -1.05 msec.degrees C-1 for P27 (r = -0.93), -1.47 msec.degrees C-1 for P40 (r = -0.95) and -0.43 msec.degrees C-1 for P40-P27 (r = -0.78). This study suggests that nasopharyngeal temperature measurement is required to aid the interpretation of PTN-SEP changes during hypothermia.

Adult↗
PubMed1992

[Effective high frequency jet ventilation setting for the preparation of internal thoracic artery for coronary artery bypass graft surgery].

Effective high frequency jet ventilation (HFJV) setting during the preparation of internal thoracic artery (ITA) was estimated in 35 patients who underwent coronary artery bypass graft (CABG) surgery. During ITA preparation, ventilation with the minimum lung movement without circulatory deterioration is necessary. Therefore, appropriate frequency, inspiratory time interval (Ti%) and working pressure (WP) for HFJV were investigated. Rising WP and prolonged Ti% provoked increasing tidal volume and decreasing PaCO2, whereas the lung extension disturbed the ITA preparation. By modifying the settings of frequency, Ti% and WP, we determined the frequency of 3Hz and Ti% of 50%. The correlation between WP at normocapnia and bodyweight (BW) is expressed in the following formula: WP = 0.16 x BW - 0.0003 (r = 0.72) Moreover satisfactory recording of end-tidal CO2 could not be obtained during HFJV. Therefore, we used transcutaneous CO2 (tc-CO2) analyzer. The coefficient between tc-CO2 and PaCO2 was 0.95, and tc-CO2 was useful as a non-invasive monitoring of PaCO2. There was little change in blood pressure, heart rate and cardiac output during HFJV. However mean pulmonary artery pressure (mPAP) increased significantly during hypercapnia especially when PaCO2 was over 50 mmHg. This suggests that mPAP may be more sensitive to PaCO2 compared with other circulatory parameters. HFJV with these settings produced good outcome for ventilation and circulation during the preparation of ITA.

Adolescent↗
PubMed1992

[A computerized anesthesia record system: four years' experience].

A computerized anesthesia record system is in routine use for cardiovascular procedures in our operating rooms. This system is implemented on an NEC PC-9801 personal computer and automatically collects hemodynamic variables from a polygraph as well as from intraoperative laboratory reports via RS-232C ports. Events such as intubation can be entered manually using a standard keyboard. Since the introduction of the system in 1987, the system has been used in 90 percent of the total cases performed and 2941 electronic data files were recorded in a four-year period. Excluding some short procedures for which the system was not used, failure to store records on disks resulted from system errors due to power-line troubles in the operating rooms as well as users' omission to command the system. User-acceptance of event entry was poor. In 74 percent of the cases, not a single event was entered. Advantage of an automated anesthesia record system over a hand-written record is being recognized. Wide-spread use of such a system will require ergonomic design of the system and man-machine interfaces suitable for use in an operating room.

Anesthesiology↗
PubMed1992

[The change in cerebral blood flow during hypotensive anesthesia induced by prostaglandin E1].

We investigated the effect of prostaglandin E1 (PGE1)--induced hypotension during sevoflurane anesthesia on the cerebral blood flow (CBF), autoregulation and internal jugular venous O2 tension (PjO2) in 8 patients undergoing neurosurgery. Although the mean arterial pressure decreased from 95.3 +/- 3.8 mmHg (mean +/- SD) to 63.6 +/- 8.0 mmHg by continuous intravenous infusion of PGE1, CBF did not change significantly (97.2 +/- 10.6% of control value). During hypotensive anesthesia, autoregulation was well maintained in all patients, and the values of PjO2 did not suggest brain hypoxia at all. The results indicate that hypotensive anesthesia induced by PGE1 and sevoflurane is a safe and a reliable method for neuroanesthesia.

Adult↗
PubMed1991

Anaesthetic management of phaeochromocytoma associated with tricuspid atresia.

The anaesthetic management of a patient with phaeochromocytoma, tricuspid atresia and pulmonary vascular stenosis is reported. The patient received no preoperative preparation with adrenergic blockers. Anaesthesia was induced and maintained with fentanyl, diazepam and sevoflurane. Intraoperative blood pressure was controlled with sodium nitroprusside, sevoflurane, phentolamine, and propranolol. For hypotension after resection of the tumour norepinephrine was required. This patient did not have a systemic to pulmonary shunt procedure performed, so the maintenance of pulmonary blood flow in the presence of haemodynamic instability during operation for phaeochromocytoma was a major concern. Monitoring of oxyhaemoglobin saturation (SpO2) with a pulse oximeter was considered to be useful because SpO2 may reflect pulmonary flow. During serious haemodynamic disturbances due to the manipulation of the tumour, the heart rate was inversely correlated with SpO2, but the relationship between mean arterial pressure and SpO2 was weak. Therefore, control of heart rate appeared to be more important than control of blood pressure in this case.

Adolescent↗
PubMed1991

Detection of coronary blood flow associated with left main coronary artery stenosis by transesophageal Doppler color flow echocardiography.

Demonstration of disordered blood flow in a coronary artery may be helpful in anticipating the presence of stenosis. To examine the possibility of disordered coronary blood flow associated with left main coronary stenosis, left main coronary flow was visualized by transesophageal Doppler color flow echocardiography in 52 patients undergoing coronary angiography. Twenty patients had significant left main coronary stenosis (Group 1) and 32 patients did not (Group 2). Adequate two-dimensional echocardiographic images of the left main coronary artery were obtained in 17 patients in Group 1 and 30 patients in Group 2. Sixteen patients in Group 1, including five patients in whom the stenosis could not clearly be defined by two-dimensional echocardiography, exhibited the aliased reddish-yellowish elements producing the mosaic pattern at the stenotic or poststenotic segments, or both. In contrast, nonaliased bluish jets, suggesting laminar flow away from the transducer, were seen in echocardiograms from 27 patients in Group 2. This group included four patients with stenosis-like images on two-dimensional echocardiography. The aliased mosaic pattern was found in only three patients in Group 2 (p less than 0.01). Thus, sensitivity to detect the stenosis was improved when Doppler color flow imaging was applied. Flow velocity was significantly higher at the site of stenosis in patients in Group 1 (116 +/- 28 cm/s, n = 10, mean +/- SD) than in Group 2 (29 +/- 12 cm/s, n = 21, p less than 0.01), suggesting that the augmentation of flow velocity with or without turbulence due to the stenosis contributed to the appearance of the mosaic flow images.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Flow Velocity↗
PubMed1991

Myocardial epinephrine sensitization with subanesthetic concentrations of halothane in dogs.

The authors investigated myocardial epinephrine sensitization by subanesthetic concentrations of halothane. The dose-response relationship for the action of halothane was examined with etomidate plus varying subanesthetic concentrations of halothane in dogs. The arrhythmogenic threshold of epinephrine was decreased in a dose-dependent manner at end-tidal concentrations of halothane between 0.1 and 0.3%. At end-tidal halothane is greater than 0.3%, and no further reduction of arrhythmogenic threshold of epinephrine occurred. The plasma concentrations of epinephrine producing four or more premature ventricular contractions in 15 s were 201.3 +/- 34.3, 98.1 +/- 13.9, 60.3 +/- 8.63, 57.9 +/- 12.8, 54.5 +/- 8.61, and 53.9 +/- 4.86 ng/ml (mean +/- SEM), at 0, 0.1, 0.3, 0.5, 1.0, and 1.5% of halothane at end-tidal concentrations, respectively. The results suggest that in the presence of etomidate, halothane produces myocardial sensitization to epinephrine at subanesthetic concentrations as low as 0.1%. Increasing halothane to 0.3% produces a further reduction in the arrhythmogenic dose of epinephrine.

Anesthesia↗
PubMed1991

Dexmedetomidine prevents epinephrine-induced arrhythmias through stimulation of central alpha 2 adrenoceptors in halothane-anesthetized dogs.

Since alpha 2-adrenergic agonists have important effects on the adrenergic system that have recently been applied to the anesthetic setting, we investigated the effect of stimulation of alpha 2 adrenoceptors on epinephrine-induced arrhythmias in halothane-anesthetized dogs. The arrhythmogenic threshold for epinephrine was determined during halothane anesthesia in the presence of dexmedetomidine, a selective alpha 2 agonist, and L-medetomidine, a stereoisomer of medetomidine that lacks alpha 2-agonist activity. Dexmedetomidine increased the arrhythmogenic threshold for epinephrine in a dose-dependent manner during halothane anesthesia. At the highest dose of dexmedetomidine, 0.5 microgram.kg-1.min-1, there was a three-fold increase in both the arrhythmogenic dose of epinephrine and the plasma epinephrine concentration that was reached at this dose. On the other hand, L-medetomidine over the same dose range did not effect the arrhythmogenic dose of epinephrine. Atipamezole, a central alpha 2 antagonist that crossed the blood-brain barrier, blocked the antiarrhythmic action of dexmedetomidine. L-659,066 a peripheral alpha 2 antagonist that does not penetrate the blood-brain barrier, did not affect the antiarrhythmic action of dexmedetomidine. Thus, dexmedetomidine's antiarrhythmic effect on epinephrine-induced arrhythmias during halothane anesthesia appears to be mediated at least in part by stimulation of central alpha 2 adrenoceptors.

Adrenergic alpha-Agonists↗
PubMed1991

Roles of beta 1- and beta 2-adrenoceptors in the mechanism of halothane myocardial sensitization in dogs.

The authors investigated the comparative roles of beta 1- and beta 2-adrenoceptors in myocardial sensitization by halothane in dogs. The arrhythmogenic dose (AD) of isoproterenol was determined in the presence of various doses of phenylephrine during halothane anesthesia in dogs, and the influences of 1-metoprolol (beta 1-antagonist) and ICI-118,551 (beta 2-antagonist) on the AD were examined. In the presence of 1-metoprolol, the AD of isoproterenol was significantly greater than the control, but in the presence of ICI-118,551, the AD of isoproterenol was lower. Blood pressure during the arrhythmias was higher in the presence of ICI-118,551 than that in controls. In addition, the AD of ritodrine (beta 2-agonist) was also determined at various doses of phenylephrine. The interaction between phenylephrine and ritodrine in inducing arrhythmias showed hyperbolic isoboles. However, 1-metoprolol completely inhibited the occurrence of arrhythmias induced by ritodrine and phenylephrine. The results suggest that myocardial beta 1-adrenoceptors play an essential role in the genesis of arrhythmias during halothane anesthesia in dogs, whereas beta 2-adrenoceptors do not.

Adrenergic beta-Agonists↗
PubMed1991

[Leukocyte removability of a newly developed filter, RC-100, in rapid transfusion].

Leukocyte-depleted blood products are currently a burning issue in transfusion medicine. As methods for depleting leukocytes, the bedside filters are shown to have a high removal rate and several kinds of them are in use. We investigated the leukocytes removal rate of a new filter RC-100 (Pall Co., Glen Cove, NY) under the condition of rapid rate of transfusion during operations. In flow rates of 30, 60, 100 ml.min-1, the removal rate of leukocytes for CRC were 99.9 +/- 0.06, 100.0 +/- 0.00 and 99.4 +/- 0.20% respectively, and for WB 100.0 +/- 0.00, 99.9 +/- 0.10 and 99.1 +/- 0.70%, respectively. The recovery rates of erythrocytes were not significantly decreased for CRC and for WB in all flow rates. These results suggest that RC-100 could be useful either for CRC and for WB even with the rapid flow rate under 100 ml.min-1.

Blood Transfusion↗
PubMed1991

Phenytoin prevents epinephrine-induced arrhythmias through central nervous system in halothane-anesthetized dogs.

The authors investigated the effect of phenytoin through the central nervous system on epinephrine-induced arrhythmias in halothane-anesthetized dogs. The arrhythmogenic dose (AD) of epinephrine during halothane anesthesia was determined in the presence of phenytoin (1 mg/kg), vehicle, and saline, which were administered directly into the cisterna magna. Phenytoin increased the AD of epinephrine as compared with vehicle or saline. The cerebrospinal and plasma concentration of phenytoin during the arrhythmias were 23.6 and less than 0.5 micrograms/ml, respectively. There was no significant difference in AD between the vehicle and saline groups. The same dose of phenytoin (1 mg/kg) administered intravenously did not affect the AD of epinephrine, and the plasma concentration of phenytoin during the arrhythmias was 1.2 micrograms/ml. These findings suggested that phenytoin exerts a protective effect against halothane-epinephrine arrhythmias through a central mechanism and that the central nervous system may be involved, at least in part, in the myocardial sensitization by halothane.

Anesthesia↗
PubMed1991

[The effects of thromboxane receptor antagonist on hemodynamic responses after neutralization of heparin by protamine].

In a double blind test, the effects of ONO 3708, thromboxane A2 (TXA2) receptor antagonist, on hemodynamic responses after neutralization of heparin by protamine, were evaluated in 19 patients undergoing coronary artery bypass graft. Severe circulatory disturbances were not observed in all patients after intravenous administration of protamine (3 mg.kg-1) over 5 minutes, and in particular ONO 3708 (2.5 micrograms.kg-1.min-1 given with continuous infusion) group (n = 10) showed no deleterious hemodynamic responses to protamine. On the other hand, in placebo group (n = 9) the mean pulmonary artery pressure (mPAP) and the mean pulmonary/systemic artery pressure ratio (Pp/Ps) increased significantly, immediately following protamine administration, compared with the baseline values and ONO 3708 group. The results suggest that pulmonary hypertension after protamine is associated with TXA2 release and that ONO 3708 is useful to avoid this reaction.

Aged↗
PubMed1990

[Response to CO2 and autoregulation of cortical cerebral blood flow during isoflurane anesthesia].

Response to CO2 and autoregulation of cortical cerebral blood flow (CBF) during isoflurane anesthesia were studied in 10 patients undergoing neurosurgery. The patients were anesthetized with 0.5 to 1.2% end-tidal isoflurane and 66% nitrous oxide in oxygen. The CBF was measured by thermal diffusion using a flow probe with a Peltier stack. PaCO2 was controlled to produce hypocarbia, normocarbia and hypercarbia by changing tidal volume and respiratory rate. Arterial blood pressure was altered. Hypotension was achieved by intravenous infusion of trimetaphan and hypertension was induced by intravenous administration of metaraminol. During isoflurane anesthesia the response to CO2 of CBF was kept at PaCO2 between 27.8 and 53.9 mmHg. The following relationship was obtained. CBF = 2.54 x PaCO2-53.0, r = 0.59, n = 131 The autoregulation of CBF was evaluated in 7 patients, and in 2 patients, the autoregulation of CBF was abolished.

Anesthesia, Inhalation↗
PubMed1989

[Impaired B lymphocyte function during open heart surgery].

Sequential in vitro lymphocyte function tests in 13 patients undergoing cardiac operation were performed to study B lymphocyte function following operation. Lymphocytes were stimulated with phytohemagglutinin (PHA), pokeweed mitogen (PWM) and Staphylococcus aureus Cowan 1 (SAC). Mitogen responses were measured by 3H-labeled thymidine incorporation. The SAC responses were significantly depressed following operation. Immunoglobulin secreting cells were measured by protein A plaque forming cell assay. The numbers of immunoglobulin secreting cells induced by PWM or SAC decreased remarkably at least as long as 3 day after the operation. The percentage of circulating B lymphocytes increased significantly postoperatively. This indicates that the B lymphocytes remaining after the operation were functionally impaired.

Antibody-Producing Cells↗