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Biomedical subjects

R Shimizu

Publications and source records attributed to R Shimizu.

At least 127 records · Page 7Linked to original sources
PubMed1995

Spread of subarachnoid hyperbaric amethocaine in pregnant women.

In order to examine how the gestational period influences the spread of spinal anaesthesia, we have measured the extent of spinal block produced by hyperbaric amethocaine 8 mg in 90 women. The patients were allocated to one of five groups according to the gestational period: non-pregnant group (n = 17), first trimester group (6-12 weeks, n = 14), second trimester group (13-24 weeks, n = 26), third trimester group (25-36 weeks, n = 15) and term group (37-41 weeks, n = 18). Maximum cephalad spread of analgesia was significantly higher in the second trimester (median T3 (range T9-C6)), third trimester (T3 (T4-C7)) and term groups (T2.5 (T4-C8)) than in the nonpregnant (T4 (T8-T2)) and first trimester groups (T4 (T11-C7)). We found that not only term pregnancy but also second and third trimester pregnancies enhanced the spread of spinal anaesthesia, and that first trimester pregnancy did not affect the spread of spinal anaesthesia.

Adult↗
PubMed1995

Anatomical configuration of the spinal column in the supine position. I. A study using magnetic resonance imaging.

In order to clarify the anatomical configuration of the spinal column in the supine position, we have examined T1-weighted sagittal midline magnetic resonance images of the spinal column in 20 healthy volunteers (11 men, nine women) in the supine position. The mean maximum angles of decline of the lumbar spinal canal in men and women were 12.6 (SD 3.9) degrees and 13.4 (3.3) degrees in the cephalad direction, respectively. The maximum angles of incline of the upper thoracic spinal canal in men and women were 20.3 (4.0) degrees and 18.5 (2.5) degrees, respectively. The median highest points of the lumbar spinal canal in men and women were located at L4 (range L3-4 to L4) and L4 (L4), respectively. The lowest point of the thoracic spinal canal was located at T8 (T7-T9) in both men and women. We have demonstrated that both lumbar lordosis and thoracic kyphosis differ between individuals, particularly with respect to the lowest point of the thoracic spinal canal, which is located between T7 and T9.

Adolescent↗
PubMed1995

Anatomical configuration of the spinal column in the supine position. II. Comparison of pregnant and non-pregnant women.

To assess the changes in the curvature of the spinal column in the supine position during pregnancy, we studied seven pregnant (32-37 weeks of pregnancy) and seven non-pregnant women using magnetic resonance imaging. T1-weighted sagittal midline magnetic resonance images of the spinal column were obtained with subjects in the supine position with left tilt. There was no significant difference in the maximum angle of decline of the lumbar spinal canal between the pregnant (mean 12.4 (SD 3.3) degrees) and non-pregnant (13.4 (3.9) degrees) groups. The maximum angle of incline of the upper thoracic spinal canal was smaller in the pregnant (15.8 (2.9) degrees) than in the non-pregnant (22.7 (6.0) degrees) group. The highest point of the lumbar spinal canal was located at a lower lumbar region in the pregnant (median L4-5 (range L4 to L4-5)) than in the non-pregnant (L4 (L3-4 to L4)) group. The lowest point of the thoracic spinal canal was located at a higher thoracic region in the pregnant (T6-7 (T6 to T7-8)) than in the non-pregnant (T8 (T6-7 to T9)) group. This study revealed that the apex of lumbar lordosis was caudad and thoracic kyphosis was reduced in the supine position in the later stages of pregnancy. These changes in the curvature of the spinal column may explain, in part, the enhanced cephalad spread of subarachnoid hyperbaric anaesthetic solutions in the later stages of pregnancy.

Adult↗
PubMed1995

Visceral pain during caesarean section: effect of varying dose of spinal amethocaine.

The aim of this study was to determine how varying the dose of spinal amethocaine influences the incidence of visceral pain associated with exteriorization of the uterus after delivery. In a double-blind study, we examined the incidence of visceral pain in 40 parturients undergoing Caesarean section under spinal anaesthesia with amethocaine 8, 10, 12 or 14 mg in 2 ml of 5% glucose. The dose of spinal amethocaine was found to influence the incidence of visceral pain associated with exteriorization of the uterus after delivery. The incidence of visceral pain was lower in the 12-mg (P < 0.05) and 14-mg (P < 0.01) groups than in the 8-mg group, although there were no differences in maximum spread of analgesia and circulatory changes between the four groups. This study suggests that a slightly higher dose of spinal amethocaine (12-14 mg) is preferable for Caesarean section.

Adult↗
PubMed1995

Effects of graded infusion rates of propofol on cardiovascular haemodynamics, coronary circulation and myocardial metabolism in dogs.

We have studied the effects of a 30-min infusion of propofol 6, 9, 12, 15, 18 and 21 mg kg-1 h-1 on cardiovascular haemodynamics, coronary circulation and myocardial metabolism in 12 mongrel dogs. Mean plasma concentrations of propofol after infusion of 6 and 21 mg kg-1 h-1 increased from 2.9 (SEM 0.3) to 11.5 (0.1) micrograms ml-1. Propofol produced a progressive decrease in arterial pressure. Heart rate tended to decrease at 15, 18 and 21 mg kg-1 h-1 and cardiac index decreased significantly at infusion rates > or = 9 mg kg-1 h-1. Systemic vascular resistance tended to increase except at 21 mg kg-1 h-1 and left ventricular systolic and diastolic function were depressed. Both coronary sinus blood flow and myocardial oxygen consumption decreased in parallel with a decrease in left ventricular minute work index without producing lactate. Propofol produced progressive decreases in coronary blood flow and myocardial oxygen consumption but did not exert adverse effects on the coronary circulation.

Anesthetics, Intravenous↗
PubMed1995

Cerebrospinal fluid progesterone in pregnant women.

To assess the possible relationship between an increase in progesterone concentration in cerebrospinal fluid (CSF) and enhancement of spread of spinal anaesthesia, we have measured CSF progesterone concentrations in 134 patients undergoing spinal anaesthesia with hyperbaric amethocaine 8 mg. Patients were allocated to one of five groups according to the gestational period: non-pregnant group (n = 13), first trimester group (8-12 weeks, n = 16), second trimester group (13-24 weeks, n = 18), third trimester group (25-36 weeks, n = 38) and term group (37-41 weeks, n = 49). Progesterone concentration in CSF was higher in the third trimester and term groups than in the non-pregnant, first trimester and second trimester groups. Maximum cephalad spread of analgesia was higher in the second trimester, third trimester and term groups than in the non-pregnant and first trimester groups. Although an increase in CSF progesterone concentration in the second trimester group was similar in magnitude to that observed in the first trimester group, enhanced spread of spinal anaesthesia, comparable in magnitude with that observed in the term group, occurred in the second trimester group. There was no significant correlation between CSF progesterone concentration and spread of spinal anaesthesia in any of the groups. These data suggest that not only a minimum level of progesterone in CSF but also a certain duration of exposure to elevated CSF progesterone concentrations may be necessary for enhancement of spread of spinal anaesthesia, and that values of CSF progesterone concentration do not correlate directly with enhancement of spread of spinal anaesthesia.

Adult↗
PubMed1995

Extensive extradural spread in the elderly may not relate to decreased leakage through intervertebral foramina.

It has been suggested that the extensive longitudinal extradural spread of local anaesthetics in the elderly is attributed to decreased leakage through the intervertebral foramina. We have examined radiologically, in 53 patients, the relationship between leakage of iohexol through the thoracic intervertebral foramina and age. Iohexol was injected through an extradural catheter advanced 5 cm cephalad from one of the interspaces between T6 and T12. A significant correlation was observed between longitudinal spread of iohexol and age, but there was no correlation between leakage of iohexol through the intervertebral foramina and age. Our data suggest that longitudinal extradural spread of local anaesthetics in the elderly may not be attributed to decreased leakage through the intervertebral foramina.

Adult↗
PubMed1995

Comparison of the effects of halothane, isoflurane, and sevoflurane on atrioventricular conduction times in pentobarbital-anesthetized dogs.

It is not known how sevoflurane affects the cardiac conduction system. We compared the effects of halothane, isoflurance, and sevoflurane on specialized atrioventricular (AV) conduction times in eight pentobarbital-anesthetized dogs. AV conduction times with three inhaled anesthetics at end-tidal concentrations of 1 and 2 minimum alveolar anesthetic concentration (MAC), were measured by His-bundle electrocardiography during both sinus rhythm and right atrial pacing at a slightly higher rate than sinus one. Heart rate and arterial pressure were simultaneously recorded. Halothane prolonged AV nodal conduction time during sinus rhythm (A-H interval) at 2 MAC compared with the control value, whereas isoflurane and sevoflurane did not alter the A-H interval, His-Purkinje conduction time (H-V interval), and ventricular conduction time (H-S interval) during sinus rhythm at 1 and 2 MAC. All three inhaled anesthetics did not change AV conduction times during right atrial pacing. No significant difference in AV conduction times was observed between isoflurane and sevoflurane. Heart rate during sinus rhythm remained unchanged despite a decrease in arterial pressure with three inhaled anesthetics. The property of sevoflurane and isoflurane which does not affect the cardiac conduction system may be important in the stability of the cardiac rhythm during anesthesia with these drugs.

Anesthesia, Intravenous↗
PubMed1995

Amrinone is superior to epinephrine in reversing bupivacaine-induced cardiovascular depression in sevoflurane-anesthetized dogs.

BACKGROUND: Bupivacaine-induced cardiovascular depression is known to be difficult to treat, and the efficacy of epinephrine for treatment of bupivacaine-induced cardiovascular depression is in doubt. We compared the efficacy of amrinone with that of epinephrine for the treatment of bupivacaine-induced cardiovascular depression in anesthetized dogs. METHODS: In dogs receiving 1.5-2% sevoflurane anesthesia, 0.5% bupivacaine was infused at a rate of 0.5 mg.kg-1.min-1 intravenously until mean arterial blood pressure decreased to 40 mmHg or less. In the amrinone group (n = 9), amrinone (4 mg.kg-1, intravenously) was given immediately after cardiovascular depression, followed by intravenous infusion at a rate of 0.1 mg.kg-1.min-1. In the epinephrine group (n = 9), epinephrine (0.01 mg.kg-1, intravenously) was given as a bolus, and the same dose was given again as required. RESULTS: All nine dogs that received amrinone survived. Of the nine dogs that received epinephrine, five survived; fatal cardiovascular depression developed in the four remaining animals (P < 0.05). Only one animal in the amrinone group showed tachyrhythmia with wide QRS complexes during resuscitation, whereas all nine animals in the epinephrine group showed tachyrhythmia with wide QRS complexes during resuscitation. CONCLUSIONS: Amrinone is superior to epinephrine for the treatment of bupivacaine-induced cardiovascular depression in sevoflurane-anesthetized dogs.

Amrinone↗
PubMed1995

Nitric oxide synthase inhibition is detrimental to cardiac function and promotes bronchospasm in anaphylaxis in rabbits.

We studied the effects of a nitric oxide synthase (NOS) inhibitor, N omega-nitro-L-arginine-methyl ester (L-NAME), on cardiac depression and bronchospasm provoked by systemic anaphylaxis in vivo in rabbits. Animals pretreated with L-NAME showed lower survival rates than control animals pretreated with normal saline. The survival rate in L-NAME-pretreated animals was increased by the administration of L-arginine after initiation of anaphylaxis. Cardiac output fell significantly in animals pretreated with L-NAME compared with controls, although venous return was increased. In animals pretreated with L-NAME, pulmonary resistance was significantly increased, and administration of arginine attenuated the bronchospasm. In conclusion, these results, along with the low survival rates in the L-NAME-treated animals, suggest that NO production may be beneficial to cardiac depression and bronchospasm in anaphylaxis in vivo.

Analysis of Variance↗
PubMed1995

Evaluation of left ventricular diastolic function in IgE-mediated anaphylaxis in dogs.

Depressed left ventricular (LV) systolic function remains controversial in patients with anaphylaxis and anaphylactic animal models. However, LV diastolic function has not yet been investigated in either patients or animal models. Therefore, we assessed LV diastolic and systolic function in IgE-mediated anaphylaxis in dogs. Seven dogs sensitized to Ascaris suum antigen were studied. An aqueous extract of Ascaris suum antigen was administered over 30 s into the systemic circulation to induce anaphylaxis. To assess LV function, the time constant of the fall of isovolumic LV pressure (T), as an index of LV diastolic function, and the maximum rate of rise of LV pressure (dP/dtmax), as an index of LV systolic function, were measured for a period of 120 min after antigen challenge. T was prolonged during the period of 5 to 15 min; however, changes in T were not significantly different from prechallenge values. LV d}/dtmax significantly decreased to 0.49 +/- 0.12 times the prechallenge value 5 min after antigen challenge, and significantly increased during the period from 30 to 120 min. However, these changes in dP/dtmax almost paralleled the changes in LV end-diastolic pressure, indicating that left ventricular systolic function was relatively well preserved. In conclusion, LV diastolic function, i.e., isovolumic relaxation, is little impaired in anaphylaxis, and LV systolic function is relatively well preserved during the early stage following the onset of anaphylaxis.

Anaphylaxis↗
PubMed1995

Canine plasma erythropoietin levels in 124 cases of anemia.

Erythropoietin (EPO) levels in plasma from 124 clinically anemic dogs were determined by in vivo bioassay. In 81 anemic dogs with normal renal function, the concentration of plasma EPO showed a close correlation with the hemoglobin concentration. The plasma EPO level was obviously decreased in 43 anemic dogs with renal failure. Of these dogs with renal failure, 17 showed no detectable plasma EPO and resulted in the death of these dogs. In the remaining 26 dogs having detectable plasma EPO, the plasma concentration rate of EPO related to blood urea nitrogen and serum creatinine values.

Anemia↗
PubMed1995

Changes in skeletal muscle composition in response to swimming training for young horses.

To investigate muscular adaptation to swimming training in young horses, 18 two-year-old Thoroughbred horses were trained in a program which included both running and swimming, and the changes in skeletal muscle composition during the training period were evaluated histochemically. The horses were divided into the following three groups; Group A, trained by running only: Group B, trained by running plus a gradual increase in swimming; Group C, trained by running plus constant swimming. In Groups B and C, fast twitch-low oxidative (FT) fibers tended to decrease, while fast twitch-high oxidative (FTH) fibers to increase with the training progressed. The tendency was more remarkable in Group B. Therefore, in these two groups, it was suggested that the horses' aerobic capacity at the muscular level was improved significantly.

Aging↗
PubMed1995

Preventive effects of recombinant human erythropoietin administration on anemia associated with repeated hemodialysis in nephrectomized dogs.

The preventive effects of recombinant human erythropoietin (rhEPO) administration on progression of anemia were evaluated during hemodialysis in nephrectomized dogs. In control dogs given no rhEPO, anemia gradually progressed with repeated hemodialysis and with little erythropoietic response observed in the bone marrow. In dogs administered with rhEPO, however, an active erythropoietic response was induced in the bone marrow, indicating that anemia due to hemodialysis was being prevented.

Anemia↗
PubMed1995

[A case of multiple liver metastasis from ileac carcinoid effectively treated with continuous intraarterial infusion of somatostatin analog].

We report a case of multiple liver metastasis from ileac carcinoid treated with continuous intraarterial infusion of somatostatin analog. A 65-year-old man who complained of chest pain was admitted to Yamaguchi University Hospital School of Medicine for further examination of cardiac angina. Liver tumors, which were detected during ECHO cardiogram examination, were diagnosed as metastasis from carcinoid by percutaneous transhepatic liver biopsy. Primary tumor was found at the ileum by colonofiberscopy. We performed ileo-cecal resection and catheterization from the gastroduodenal artery for intraarterial chemotherapy under laparotomy. After the operation, the patient was treated with continuous intraarterial infusion of somatostatin analog (100 micrograms/day, 5 days/week for 16 weeks). The tumor in segment 6 (S6) disappeared, but the tumor in S2 enlarged after the therapy. Hepatic angiography confirming the drug distribution demonstrated the occlusion of the left hepatic artery. This drug was thus distributed to the tumor in S6 but not in S2. These results suggest that somatostatin analog may have a direct anti-tumor effect. Furthermore, no side effect was observed. Thus, intraarterial infusion of somatostatin analog may be a useful therapy for liver metastasis from carcinoid.

Aged↗
PubMed1995

[Continuous monitoring of arterial blood oxygen saturation with a pulse oximeter during spinal anesthesia].

The arterial oxygen saturation was continuously monitored in 50 patients under spinal anesthesia. Of the 50 patients, low oxygen saturation below 95% and/or its decrease of more than 5% was observed in 19 patients (38%). The remaining 31 patients (62%) showed a normal oxygen saturation. Pentazocine 0.5 mg.kg-1 i.v. correlated significantly with arterial oxygen desaturation (P = 0.0001). It is possible that laparotomy is associated with the desaturation (P = 0.0582). No correlation between desaturation and the other factors (level of analgesia, position during operation, and hydroxyzine premedication) was found.

Adolescent↗