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Biomedical subjects

S Oku

Publications and source records attributed to S Oku.

At least 37 records · Page 2Linked to original sources
PubMed1995

[The influences of local anesthetics on ryanodine-induced contracture in rat skeletal muscle].

One hundred and fifty paired extensor long digital muscles were excised from Wistar rats and each muscle was prepared in Krebs-Ringer's solution (K-R solution) then gassed with a mixture of 95% O2-5% CO2. The medium for the control muscles was replaced with K-R solution containing 10(-6) M ryanodine and that for the experimental muscles was replaced with medium containing 10(-6) M ryanodine and local anesthetic (LA) (procaine, tetracaine, benzocaine, lidocaine or bupivacaine at various concentration). Isometric contracture tension was recorded throughout the experiment. The ratios of the maximal contracture tension (C-ratio) and the elapsed time (T-ratio) of the muscles treated with LA compared to those of control muscles were calculated. Tetracaine (0.125-1.0 mM) specifically reduced the C-ratio. Procaine (0.5-1.0 mM) and tetracaine (10-60 microM) increased the T-ratio. Procaine (8-16 mM), benzocaine (4-8 mM), lidocaine (0.5-4 mM) and bupivacaine (0.125-1 mM) reduced the T-ratio. The influences of LAs on ryanodine-induced contracture could be explained in terms of their effects on the Ca(2+)-induced Ca2+ release mechanism, direct Ca2+ efflux from sarcoplasmic reticulum (SR), activity of Ca2+ uptake into SR and ryanodine-receptor binding. The complexity of LA effects on ryanodine-induced contracture will affect the results of ryanodine contracture tests for malignant hyperthermia when the muscle specimen is excised under local anesthesia.

Anesthetics, Local↗
PubMed1995

Screening for QT prolongation using a new exponential formula.

We prospectively screened 14,227 school-aged children for evidence of QT prolongation using a exponential formula (eQTc = (QT interval)/(RR interval)0.31) and criteria (ie: abnormal eQTc was defined as being equal to or greater than 0.430 and 0.435 for male and female first-graders, respectively, and 0.440 and 0.445 for male and female seventh-graders, respectively). We previously reported that this new exponential correction of the QT interval may be useful for eliminating the effect of heart rate in school-aged children. Computer analyses detected 13 children with abnormally prolonged eQTc. All of the children who had abnormal QTc values by conventional QTc criteria also had abnormal eQTc values using the new criteria. Nine of these 13 children were ultimately confirmed to have a prolonged QT interval. Six cases of QT prolongation were detected that would not have been found if conventional screening criteria were used, since these cases had heart rates greater than 75 beats/min. One child had parents who were deaf. This case would not have been detected if only conventional screening were used. These results suggest that exponential correction of the QT interval (eQTc) is useful for prospectively screening large populations for evidence of QT prolongation.

Child↗
PubMed1995

Correction of the QT interval in children.

We evaluated the usefulness of 11 formulas for correcting the QT interval in children, including the square root, cubic root, logarithmic, linear, exponential, and inverse formulas using the Mean-squared residual (MSR) values and Akaike Information Criterion (AIC) in 8,086 first-graders, 9,989 seventh-graders, and 5,786 tenth-graders. The subjects were divided into six groups according to age and sex. MSR and AIC values were lowest in all of the groups for the exponential formula (eQTc) and Fridericia's formula (fQTc). We then evaluated the relative usefulness of these two formulas by determining the optimal value for parameter k using the following exponential model: eQTc = (QT interval)/(RR interval)k. The best-fit value for k was different for each group. However, the tentative abnormal eQTc and fQTc values, determined by statistical analysis, were equivalent in all groups when 0.31 was used as the exponential parameter k. These results suggest that the exponential formula and Fridericia's formula are equally useful for screening for QT prolongation.

Adolescent↗
PubMed1994

Effect of obesity on echocardiographic parameters in children.

We studied the effect of obesity on echocardiographic parameters in Japanese children. The subjects were 341 children: 106 first graders (age 6 years), 166 seventh graders (age 12 years), and 69 tenth graders (age 15 years). They were assigned to six groups according to school grade and sex. Echocardiographic parameters included thickness of the interventricular septum and of the posterior wall, end diastolic left ventricular internal dimension, and left ventricular mass. Left ventricular parameters were normalized for height, and for height to the power of 2.7. The obesity index as well as the body mass index were used to estimate obesity, because the obesity index is frequently used in Japan. There were significant correlations between the indices of obesity and left ventricular internal dimension or left ventricular mass in each group. The obesity index was more strongly correlated than the body mass index with posterior wall thickness and left ventricular internal dimension. For normalization of left ventricular parameters, correction for height was better for the first graders, whereas correction for height to the power of 2.7 was better for seventh and tenth graders. The most important finding was that the effect of obesity on left ventricular parameters was evident at 6 years of age.

Adolescent↗
PubMed1994

[Sick sinus syndrome discovered after induction of general anesthesia in a patient with normal preoperative Holter ECG].

We reported a case of 50-year-old male who was found to have SSS after induction of general anesthesia though his preoperative cardiac function studies including Holter ECG were normal. He was scheduled to have anterior transposition of ulnar nerve for idiopathic ulnar nerve palsy. He had suffered from lung edema during the same operation about 10 months previously at another hospital and the cause had been unknown. We monitored direct radial artery pressure continuously before induction of general anesthesia. About 5 minutes after the induction, ECG showed bradycardia of less than 40.min-1 and systolic blood pressure decreased to 40 mmHg. Intravenous injection of atropine increased heart rate to 60.min-1 only transiently. We began continuous infusion of isoproterenol. It was effective and no bradycardia and hypotension occurred afterwards throughout the operation. About 2 months later, he showed severe dizziness and Holter ECG revealed sinus arrest for 5 seconds. Therefore, a permanent pacemaker was implanted.

Anesthesia, General↗
PubMed1994

[Emergency operation and perioperative management for a patient with strangulated ileus and shock associated with Rubinstein-Taybi syndrome].

A 21-year-old white male with Rubinstein-Taybi syndrome (RTS) underwent emergency laparotomy and volvulus reduction for a strangulated ileus. Low blood pressure, rapid heart rate and dusky skin color indicated that he was in a hypovolemic and/or septic shock state. Communication with the patient was impossible because of severe mental retardation, deafness, and blindness, and he was quite combative and agitated. Because of an urgent situation and in anticipation of a great risk of regurgitation, no sedatives or anesthetics were used for induction of anesthesia. A large dose of vecuronium with a priming principle technique was the only agent used for endotracheal intubation. Vigorous fluid replacement and appropriate catecholamine therapy were required for the perioperative management and recovery from the shock state. Any cardiac episodes which have been reported in patients with RTS, such as supra-ventricular or ventricular arrhythmia, did not occur throughout the perioperative period. Lack of communication with the patient was an obstacle in the postoperative care, such as respiratory management or the estimation for the timing of extubation. In conclusion, the preparations for a possibly difficult airway and the possible occurrence of arrhythmia were thought to be prudent for the management of the patient with RTS.

Adult↗
PubMed1993

Estimation of myocardial damage in Kawasaki disease using antimyosin antibody.

In a retrospective study, 121 children with Kawasaki disease (KD) were investigated to determine (i) the incidence of myocardial damage using the antimyosin antibody (AMA) titer; (ii) the differences in the electrocardiograms between the AMA-positive and -negative patients; and (iii) the effect of treatment with intravenous gamma globulin (IVGG) on the AMA. Comparisons were made with 117 normal children (controls). Patients with KD showed a significantly higher mean AMA titer and more patients were positive for AMA than the controls. The AMA titer in the KD group was not related to the presence of coronary artery lesions. Electrocardiograms obtained during the acute and the convalescent stage of KD revealed that patients positive for AMA had a significantly lower voltage of T wave in lead V6 at week four than at week two of illness, whereas patients negative for AMA showed no T wave change after week two. The group treated with IVGG showed a significantly lower AMA titer than that not given IVGG. These observations suggest that myocardial damage occurs in some patients with KD which is unrelated to the presence of coronary artery lesions and that the treatment with IVGG reduces the AMA titer in patients with KD.

Adult↗
PubMed1993

[Early detection of absorption of irrigating fluid during transurethral resection of the prostate with alcohol gas detector tube].

Nineteen patients (mean age, 70 years; range, 58-80 years) undergoing elective transurethral resection of benign hypertrophy of the prostate (mean weight of resectate, 25 g; range 10-59 g; mean resection time, 61 min; range 45-80 min) under spinal anesthesia were studied for early detection of absorption of irrigating solution by means of expired breath alcohol analysis. The irrigating fluid used in all resections was tenfold diluted Urigal solution containing 1% ethanol. Expired breath was collected into a rubber bag every 10 min during the surgery, and the concentration of ethanol was analyzed using a gas detector tube (GASTEC LTD.). Hemodynamic parameters including central venous pressure were routinely measured at the same intervals. The volumetric fluid balance was measured every 20 min. Blood was collected preoperatively, at the same 20-min intervals during the resection, and 4-6 hours after the end of the operation. Serum electrolytes, hemoglobin and total plasma protein concentration were measured, and blood gas tension was analyzed. Mean arterial pressure, central venous pressure, blood gas tension showed no significant changes at these observed time intervals. Heart rate decreased 120 min after the start of the operation. Ethanol was detected in the expired breath 10 min after the start of the surgery, and showed progressive increase in concentration until the end of the surgery. Serum electrolyte concentrations and hemoglobin content showed gradual decrease proportional to the increase in irrigating fluid volume. The ethanol concentration in the expired breath was significantly correlated with the change in serum sodium concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗
PubMed1993

[The effect of isoflurane on plasma concentration-response curve of vecuronium determined with continuous infusion method].

To investigate the interaction between vecuronium and isoflurane at the neuromuscular junction in man, I determined the plasma concentration-response curve of vecuronium both under balanced and isoflurane (0.7% and 1.2% end-tidal) anesthesia. In addition, I also determined clinically the infusion rate of vecuronium that made a suitable sustained relaxation possible. I used train-of-four (TOF) stimulation to monitor neuromuscular blockade by vecuronium. Plasma isoflurane concentration was kept constant throughout the observation period. Plasma clearances of vecuronium calculated from the infusion rate and resulting plasma concentration were also found not to be different among the three groups. A significant leftward shift of the concentration-response (T1 inhibition) curve was found both between 1.2% isoflurane group and NLA group, and between 1.2% isoflurane group and 0.7% isoflurane group. The relationship between T1 inhibition and TOF ratio reduction was found not to be different among the three groups. I conclude that 1.2% isoflurane potentiates vecuronium-induced T1 inhibition, but it does not affect the relationship between T1 inhibition and TOF ratio reduction in man. It is helpful for clinical determination of the infusion rate to measure the time period from bolus administration of vecuronium 0.1 mg.kg-1 to reappearance of T3.

Adult↗
PubMed1993

[A new leak test of anesthetic machine].

A case of the inspired PCO2 increase secondary to the malfunction of expiratory valve due to a defected edge of creator is presented. In this case, we could not detect the malfunction of expiratory valve using the preanesthetic routine leak test but found it by observing the expiratory phase of the capnometric curve. Therefore, we devised a new leak test for checking the malfunction of inspiratory and expiratory valves. This test is simple and effective. The test consists of the following procedures.: 1. Connecting yokes to the oxygen piping system. 2. Connecting the breathing bag. 3. Occluding the inspiratory terminal. Closing the semiclosed valve completely. 4. Flushing the O2 gas and increasing the pressure of breathing circuit to 30 cmH2O. 5. Monitoring the pressure gauge of the anesthesia system. If the function of valves is normal, the system pressure decreases slowly. If either of the valves works wrong, it decreases rapidly. We checked anesthesia machines in our facilities using the new leak test, and found some cases of the expiratory valve malfunctions.

Adenocarcinoma↗
PubMed1992

Effects of tilting in the sagittal plane on the cephalad spread of anesthesia.

The effect of tilting in the sagittal plane on the spread of anesthesia was studied in 30 healthy male patients. Two ml of 0.3% hyperbaric dibucaine was used for intrathecal injection in the lateral position. After 3 min of resting on their side, 15 patients were placed in the horizontal supine position. Other 15 patients were turned to the contralateral side at 7-8 degrees in the sagittal plane. Cephalad spread of sensory analgesia by the pin-prick method, degree of motor blockade by Bromage score, mean arterial pressure, and heart rate were assessed. Mean spread of sensory analgesia in the non-dependent side on the dural puncture was significantly higher in the sagittal-tilt group (T7.4 +/- 2.6 at 15 min) compared the horizontal group (T9.5 +/- 1.4 at 15 min). There was no significant difference in the mean cephalad spread of the analgesic level in the dependent side between the two groups. Unilateral motor anesthesia of the dependent side seemed to be canceled by the sagittal tilting maneuver. A 7 to 8 degree tilt in the sagittal plane is recommended to facilitate the cephalad spread of analgesia and to avoid unilateral anesthesia.

Journal Article↗
PubMed1992

[Anesthesia for a patient with pemphigus erythematosus].

An 82-year-old female with pemphigus erythematosus had the head of femur replaced. In her case, systemic lupus erythematosus and myasthenia gravis, typical complications of pemphigus erythematosus, were not present. As even slight friction easily causes blisters in patients with pemphigus, we paid attention mainly to fragility of the skin and the mucus membranes and were careful to minimize physical stimulation of the skin. Because the mucosa of the pharynx or oral cavity could easily be damaged and form blisters during intubation, which in turn might make the management of the upper airway more difficult, we selected spinal anesthesia. No serious perioperative complications, except a few blisters around the wound were observed. We thus successfully managed anesthesia of a patient with pemphigus erythematosa.

Aged↗
PubMed1991

The effects of composition of subarachnoid gas space and anesthetic gas mixture on cerebrospinal fluid pressure changes during cisternography for transsphenoidal craniectomy.

The effects of gas composition in the subarachnoid space (injection of air or N(2)O) and in an anesthetic gas mixture (inhalation with or without N(2)O) on cerebrospinal fluid pressure were studied in 22 patients with pneumocisternography for transsphenoidal craniectomy. N(2)O (66%) anesthesia for 10 min increased cerebrospinal fluid pressure by up to 150% in 7 patients who were intrathecally injected with air. Withdrawal of N(2)O from the anesthetic gas mixture for sixty minutes reduced cerebrospinal fluid pressure to the initial pressure. A second N(2)O administration to the anesthetic gas mixture did not elevate cerebrospinal fluid pressure by as much as the first N(2)O administration. In 7 patients receiving subarachnoid air injection, replacing 66% N(2)O with 66% nitrogen prevented the change in cerebrospinal fluid pressure throughout the operation. In 8 patients N(2)O anesthesia and N(2)O intrathecal injection failed to eliminate the rise in cerebrospinal fluid pressure in 8 patients. Withdrawal of N(2)O from the anesthetic gas mixture for 60 min is recommended to prevent an extreme increase in cerebrospinal fluid pressure during pneumocisternography.

Journal Article↗
PubMed1991

Doppler echocardiographic evaluation of an infant with HCM during ACTH therapy.

Adrenocorticotropic hormone (ACTH) therapy is useful in the treatment of patients with West syndrome, and hypertrophic cardiomyopathy (HCM) in association with ACTH therapy has recently been reported. We describe the Doppler echocardiographic evaluation of an infant who had West syndrome and HCM. ACTH therapy produced increases in the interventricular septal thickness, the pressure gradient of the left ventricular outflow tract, and the heart rate. Doppler echocardiographic examination was found to be much more sensitive for monitoring the cardiac changes than either 2-dimensional echocardiography or the heart rate.

Adrenocorticotropic Hormone↗
PubMed1991

Noninvasive method to obtain input function for measuring tissue glucose utilization of thoracic and abdominal organs.

We have developed a method for the noninvasive estimation of regional tissue glucose utilization in humans that employs positron emission tomography (PET) and 2-(18F)fluoro-2-deoxy-d-glucose (FDG). Unlike other methods, the input function used in this method is obtained from the corrected time-activity curve of the descending aorta, not the left ventricle, because the descending aorta is relatively free of spillover from other organs and extends from the upper thorax to the lower abdomen. With this method the time-activity curve of the descending aorta must be corrected for the partial volume effect and the difference in counts between plasma and whole blood. Using the noninvasively obtained input function, regional tissue glucose utilization was calculated by Patlak graphic analysis. k1k3/(k2 + k3) was in good agreement with k1k3/(k2 + k3) calculated from the plasma input function by arterial sampling (r = 0.9995). These results suggest that the input function and regional tissue glucose utilization (not only of myocardium but also of other thoracic and abdominal organs) can be determined noninvasively.

Abdomen↗
PubMed1989

A simplified Master's two-step test for preschool children.

To investigate the usefulness of a simplified Master's two step test (s-MTT) for preschool children aged 4-6, s-MTT was carried out in our pediatric cardiology clinic using a new stair and connector for joining the leads from each child to the ECG machine. The subjects were 21 children with Kawasaki disease without coronary involvement and four children with arrhythmias. The treadmill exercise test (TET) was done on the same day to compare the exercise load of s-MTT with that of TET. Oxygen uptake during s-MTT was also examined using another group consisting of eight outpatients. There were no differences in indices such as peak heart rate (HR), HR immediately after exercise, and performance ratio between the outpatients in this study and kindergarteners in the preliminary report. The proportions of peak HR and HR immediately after exercise in s-MTT to those in TET were 91.1 +/- 7.9 (mean +/- SD)% and 91.1 +/- 8.6%, respectively. The average oxygen uptake of the eight outpatients in s-MTT was 23.2 +/- 4.1 ml/min/kg. These studies suggest that the simplified MTT is useful as a screening test, because it can be done for all children aged 4-6 in any laboratory.

Cardiovascular Diseases↗