Biomedical subjects

F Okumura

Publications and source records attributed to F Okumura.

At least 19 recordsLinked to original sources

PubMed1992

Continuous negative extrathoracic pressure ventilation, lung water volume, and central blood volume. Studies in dogs with pulmonary edema induced by oleic acid.

The effect of continuous positive-pressure ventilation (CPPV) on extravascular lung water volume has been investigated, but there is only one report which studied the effect of continuous negative extrathoracic pressure ventilation (CNETPV). The effect of CNETPV on central blood volume (CBV) has not been studied. Changes in intrathoracic pressure by CNETPV may alter lung water volume and CBV. In this study the effects of CNETPV on lung water volume and CBV were compared with those of intermittent positive-pressure ventilation (IPPV) and CPPV in dogs with pulmonary edema induced by oleic acid. Nine mongrel dogs were anesthetized and given oleic acid at 0.06 ml/kg intravenously to induce pulmonary edema; CNETPV was applied with a cuirass and a negative thoracic pressure ventilator (Kimura OKT-100) for 1 h. Extravascular lung water volume (as extravascular thermal volume [EVTV]) and CBV were estimated with the double-indicator dilution method using thermal-sodium; PEEP and continuous negative extrathoracic pressure were matched to produce the same increments in FRC. The EVTV increased during CNETPV but did not change during CPPV. The CBV decreased during CPPV but did not change during CNETPV. An increase of transmural pulmonary microvascular pressure was thought to be one of the reasons for the increase in EVTV with CNETPV.

Animals↗

PubMed1992

[Effect of hypotensive anesthesia on tissue oxygen tension of the heart, kidney and liver].

The effects of hypotensive anesthesia by prostaglandin E1 (PGE1: 8 dogs) or trimetaphan (TMP: 8 dogs) on tissue oxygenation were studied in 16 mongrel dogs anesthetized with pentobarbital. Mean blood pressure (MBP), heart rate (HR), cardiac output (CO), blood gases (BG), the blood flow and tissue oxygen tension of the heart, the kidney and the liver were measured. The blood flow and oxygen tension were measured by electromagnetic flowmeters and by polarographic oxygen electrodes respectively. PGE1 or TMP was injected intravenously to decrease MBP by 30%. MBP, CO, HR and BG of PGE1 were not significantly different with those of TMP. Coronary blood flow decreased for 12% with PGE1 and for 33% with TMP. Though blood flows of the renal and the hepatic arteries were well maintained with PGE1, they decreased for 36% and 34% respectively with TMP. Oxygen tensions of the myocardium (both outer and inner layers) and the liver were well maintained with PGE1. But with TMP, oxygen tension decreased for 23% in outer layer, for 16% in inner layer and for 31% in the liver. Oxygen tension of the kidney remained unchanged with PGE1 and TMP. The results suggest that PGE1 is more useful for the maintenance of the tissue oxygenation than TMP during hypotensive anesthesia.

Anesthesia↗

PubMed1992

[Effect of carbon dioxide (hypocapnia and hypercapnia) on regional myocardial tissue oxygen tension in dogs with coronary stenosis].

Carbon dioxide (CO2) has been well documented to act as a potent vasodilator of coronary vessels under normal conditions. But there is little data available on the effect of CO2 on the collateral perfusion of patients with coronary insufficiency. We studied the effects of CO2 on the myocardial tissue PO2 in anesthetized dogs with critical coronary stenosis. Twelve mongrel dogs were anesthetized with pentobarbital and ventilated with 100% O2 to maintain normocapnia. Electromagnetic blood flow (BF) probe was applied on the left anterior descending artery (LAD). Regional myocardial PO2 was measured at two different sites using two pairs of monopolar polarographic needle electrodes; one inserted in the epicardial (EPI) layer, and the other in the endocardial (ENDO) layer. These were placed in the regions supplied by LAD and circumflex. Following the baseline recording, critical stenosis of LAD was produced by adjusting a copper-wire clamp occluder until LADBF was reduced by 50%. After a stable normocapnic ventilation, hypocapnia was produced by hyperventilation. To induce hypercapnia, exogenous CO2 was added to the inspired gas stepwise until end-tidal CO2 fraction reached 10%. Hypocapnia resulted in a significant reduction in myocardial PO2 in both EPI and ENDO non-stenotic areas, while hypercapnia increased these PO2 values dose-dependently. After coronary stenosis, hypocapnia resulted in a small but significant reduction of PO2 in endocardial ischemic area. Hypercapnia did not induce any sign of reduced regional myocardial PO2 or evidence of regional or intramural "steal" phenomenon.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

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↗

PubMed1991

[Effect of arterial carbon dioxide tension on regional myocardial tissue oxygen tension in the dog].

We investigated the effects of arterial carbon dioxide tension on the myocardial tissue oxygen tensions of subepicardium and subendocardium in the anesthetized dogs. The study was done in fourteen open-chest mongrel dogs, weighing 13 +/- 1 kg, anesthetized with sodium pentobarbital (30 mg.kg-1 iv), and mechanically ventilated with 100% oxygen to maintain normocapnia. End tidal CO2 fraction (FECO2) was monitored continuously by capnograph. Regional myocardial tissue PO2 was measured using a monopolar polarographic needle electrode. Two pairs of combined needle sensors were carefully inserted, one in the epicardial and the other in the endocardial layer of the beating heart. Electromagnetic blood flow probe was applied on the left anterior descending artery (LAD). After a stable normocapnic ventilation, hypocapnia was induced by increasing the respiratory rate, and this mechanical hyperventilation was kept fixed throughout the experiments. To induce hypercapnia, exogenous carbon dioxide was added to the inspired gas step-wise until FECO2 reached 10%. Hypocapnic hyperventilation (PaCO2: 22 mmHg) invariably resulted in a significant reduction of coronary blood flow (LADBF) and left ventricular myocardial tissue PO2 in both epicardial and endocardial layers, while addition of carbon dioxide to the inspired gas (hypercapnic hyperventilation) reversed the change by increased LADBF and arterial PaCO2 in a dose-dependent manner. These results indicate that injudicious and severe hypocapnic hyperventilation may induce impaired myocardial tissue perfusion and oxygenation although normal cardiac output and arterial blood oxygenation are maintained.

Animals↗

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↗

PubMed1991

[The ventilatory response to CO2 during end-expiratory negative extra-thoracic pressure and PEEP].

The effects of end-expiratory negative extra-thoracic pressure (EENETP) and PEEP on the ventilatory response to CO2 were studied in seven healthy volunteers. The changes in functional residual capacity during EENETP -20 cmH2O and PEEP 5 cmH2O were 13.9 and 12.9 ml.kg-1, respectively. The slopes of CO2 response (minute ventilation/end-tidal CO2) during ZEEP, EENETP and PEEP were 0.913, 0.622, 0.693 l.min-1.mmHg-1, respectively. The slopes during EENETP and PEEP were significantly decreased. These results indicate that EENETP and PEEP could worsen the CO2 response in patients with respiratory failure, especially, with chronic obstructive pulmonary disease in which functional residual capacity is increased.

Adult↗

PubMed1991

[Respiratory flow and chest wall motion during negative extrathoracic pressure ventilation in human volunteers].

Respiratory flow and chest wall motion during negative extrathoracic pressure ventilation (NETPV) were compared with those during spontaneous breathing in 8 healthy male volunteers. Chest wall motion was evaluated by separate measurement of the changes in the cross sectional area of rib cage and abdomen, using respiratory inductive plethysmograph. During NETPV, expiratory flow was characterized by a large peak and a rapid decline at the early expiratory phase. NETPV increased the relative contribution of rib cage motion to tidal ventilation, and induced the abdominal paradoxical movements at inspiration in two volunteers. These results indicate that NETPV augments rib cage motion rather than abdominal motion, and this altered mechanics of chest wall may change intrapulmonary distribution of inspired gas.

Adult↗

PubMed1991

[Effects of continuous negative extrathoracic pressure ventilation (CNETPV) on gas exchange and hemodynamics in dogs with oleic-acid-induced pulmonary edema].

To investigate usefulness of continuous negative extrathoracic pressure ventilation (CNETPV) as a method of respiratory care for pulmonary edema, we compared effects of CNETPV on gas exchange and hemodynamics with those of CPPV in dogs with oleic-acid-induced pulmonary edema. End-expiratory negative extrathoracic pressure was adjusted to obtain the same increase in functional residual capacity as that obtained with PEEP of 10 cmH2O. Transmural pressure was calculated by subtracting intrapleural pressure from intravascular pressure. Both CNETPV and CPPV improved gas exchange, and changes in PaO2 and venous admixture were similar with two ventilatory modes. During CNETPV, PvO2 and oxygen delivery were significantly greater than those in CPPV. CPPV did not alter transmural filling pressures but decreased cardiac output, whereas CNETPV increased transmural filling pressure and preserved cardiac output. These results indicate that CNETPV can offer comparable improvement in gas exchange with CPPV, when two ventilatory modes are matched for lung volume. In addition, these results suggest that CNETPV may be superior to CPPV because of less depression of cardiac output and greater oxygen delivery to organs.

Animals↗

PubMed1990

Effects of diazepam on the carotid sinus baroreflex control of circulation in rabbits.

To examine the effects of diazepam on the carotid sinus baroreflex control of circulation, bilateral carotid occlusion was performed on 14 conscious rabbits with aortic denervation. The responses of mean arterial pressure, heart rate, cardiac output and total peripheral resistance were obtained. The haemodynamic responses to carotid occlusion were evaluated at cumulative doses of 0.5 and 1.0 mg kg-1 of diazepam. The administration of diazepam decreased cardiac output and increased total peripheral resistance significantly, but did not affect the arterial pressure and heart rate. The response of total peripheral resistance to carotid occlusion was significantly increased from 0.118 +/- 0.018 (mean +/- SE) to 0.154 +/- 0.026 mmHg min ml-1 at 1.0 mg kg-1 of diazepam. The heart rate response was attenuated significantly from 41 +/- 5 to 24 +/- 4 beats min-1 at 1.0 mg kg-1 of diazepam. Diazepam did not alter the response of arterial pressure to carotid occlusion. We suggest that the dissociated effects of diazepam on the reflex control of circulation reflect the dissociated influences of diazepam on the central sympathetic and vagal-mediated pathways.

Animals↗

PubMed1990

Effects of continuous negative extrathoracic pressure ventilation on renal function and alpha-atrial natriuretic peptide in normal individuals.

Continuous negative extrathoracic pressure ventilation (CNETPV) may induce atrial distention by augmenting venous return, resulting in the increased secretion of atrial natriuretic peptide (ANP) and natriuresis. To clarify this hypothesis, we investigated the effect of CNETPV on renal function and plasma ANP level. Nine male healthy volunteers were studied during three successive 60-minute periods under (1) spontaneous breathing, (2) CNETPV with continuous negative extrathoracic pressure of -10 cm H2O, and (3) spontaneous breathing again. Continuous negative extrathoracic pressure ventilation induced a transient increase in plasma ANP level, but changes in plasma ANP level were not statistically significant. Although there was no significant difference in urine volume and urinary sodium excretion among three successive periods, a slight but significant increase in creatinine clearance was noticed during CNETPV. These results indicate that CNETPV with continuous negative extrathoracic pressure of -10 cm H2O does not induce the major change in ANP secretion and renal function in normal subjects.

Adult↗

PubMed1990

[Infusion speed as a factor to influence the analgesic level of spinal anesthesia--hypobaric solution of tetracaine].

In spinal anesthesia, as known, the injection speed of local anesthetic drug is a factor which influences the analgesic level. For study it, automatic infusion apparatus was available to control as 5 kinds of infusion speed (0.02-0.51 mL/s), and 78 patients were divided into 6 groups. The results of the painless level was discussed by T-test and distribution analysis (F-test). The mean of painless level in each group was found to be no significant difference as discussed by T-test. But the largest distribution was found in the group of 0.04 mL/s, and high analgesic level as rise up to T6 was occasionally found in groups of 0.04 mL/s & 0.02 mL/s. It means, the infusion speed is not an important factor, but extremely slow infusion is more dangerous than high speed infusion, which will take a risk of high level spinal anesthesia.

Adult↗

PubMed1990

[Effects of negative extra-thoracic pressure ventilation on respiratory system and hemodynamics in normal dogs].

The effects of negative extra-thoracic pressure ventilation (NETPV) on respiratory system and hemodynamics were examined in ten normal dogs. Changes of the parameters obtained during intermittent NETPV (INETPV), and NETPV with negative end-expiratory pressure (CNETPV) were compared with those during IPPV and CPPV. Animals' chests and upper abdomens were confined in an acryl box. In INETPV and CNETPV, the dogs were ventilated with the negative extra-thoracic pressure ventilator (Kimura, OKT-100). Positive and negative pressure ventilation was carefully matched for tidal volume and the increase in FRC obtained with PEEP and the end-expiratory negative extra-thoracic pressure (EENETP). EENETP of -11.6 cmH2O produced the same FRC change as PEEP of 10.6 cmH2O did. Gas exchanges did not differ in any modes. INETPV did not change any hemodynamic parameters without PAP. In CNETPV, heart rate increased, and CVP, cardiac index (CI) and stroke volume (SV) decreased significantly (P less than 0.05), but tmCVP and tmPCWP did not change. The decreases of CI and SV (100----89.1, 88.8%) in CNETPV were significantly smaller when compared with CPPV (100----78.8, 74.5%). In CPPV, meanBP, CVP, tmCVP, tmPCWP, CI, SV changed significantly. The mechanisms of the decrease of CI and SV by CNETPV seemed to be different from those by CPPV.

Animals↗

PubMed1990

[Effects of negative extra-thoracic pressure ventilation on extravascular lung water volume and central blood volume in normal dogs].

In negative extra-thoracic pressure ventilation (NETPV), lung water volume and central blood volume (CBV) could increase because of increased venous return and intensified negative interstitial pressure. The effects of NETPV on the extravascular lung water and CBV were examined in ten normal dogs by the double-indicator method using Na and cold water. The lung water volume measured by the method (EVTV) was compared with the lung water volume measured by the gravimetric method (EVLW) in 17 dogs. EVTV did not show any significant change in any ventilation modes compared with IPPV. CBV decreased from 21.9 ml.kg-1 to 19.2 ml.kg-1 in CPPV compared with IPPV (P less than 0.05). EVTV correlated well (r = 0.91, P less than 0.001) with EVLW. In normal dogs, NETPV did not change the lung water volume and CBV. NETPV dogs do not seem to have any disadvantage in respect of lung water volume compared with conventional positive pressure ventilations.

Animals↗

PubMed1990

[Ventricular fibrillation after administration of aclacinomycin emulsion into mesenteric lymph nodes in a patient anesthetized with enflurane, nitrous oxide and oxygen].

A 57-year-old man was given 40 mg of activated carbon aclacinomycin (ACM) emulsion into mesenteric lymph nodes during anesthesia with enflurane, nitrous oxide, oxygen and epidural anesthesia. He had no complications preoperatively. Immediately after the injection, his skin turned to red, and 5 minutes later, sinus tachycardia, R wave amplitude reduction, T wave amplitude elevation, QT prolongation and PVCs were noted, and then, ventricular fibrillation (Vf) occurred 15 minutes after the injection. We succeeded in electrical defibrillation within about 180 seconds. At that time, both arterial blood gas and electrocytes were normal. Serum ACM concentration was remarkably elevated 60 minutes after the administration, and remained high 22 hrs later. Postoperative course was uneventful and he was discharged on the 17th postoperative day. It has been said that ACM has relatively low cardiotoxicity compared with adriamycin because of rapid distribution and metabolism. However, it might cause cardiac complication such as ECG abnormality, heart failure, pericarditis, though the effects are transient and reversible. Therefore we should be ready for its rapid treatment. Coenzyme Q10 could counteract cardiotoxicity of ACM.

Aclarubicin↗

PubMed1989

Effects of fentanyl on carotid sinus baroreflex control of circulation in rabbits.

The effects of intravenous administration of fentanyl on carotid sinus baroreflex control of hemodynamics were investigated in chronically instrumented rabbits. Carotid sinus baroreflex was assessed by bilateral carotid occlusion (BCO), and the responses of mean arterial pressure (MAP), heart rate (HR), mean ascending aortic flow (MAF), and total peripheral resistance (TPR) were obtained. Hemodynamic responses to BCO were examined with cumulative doses of 5, 10, and 15 micrograms/kg of fentanyl. Fentanyl did not affect MAP and TPR but reduced HR and MAF dose dependently. Fentanyl did not attenuate the MAP response to BCO significantly. In contrast, fentanyl significantly attenuated the TPR response from 0.126 +/- 0.003 to 0.104 +/- 0.005 mmHg.min-1.ml-1 and augmented the HR response from 31 +/- 2 to 47 +/- 3 beats/min in the conscious state and at 15 micrograms/kg of fentanyl, respectively. The administration of atropine after the fentanyl attenuated MAP and HR responses to 79.9 and 27.7% of those of 10 micrograms/kg of fentanyl, respectively. We suggest that these dissociated hemodynamic responses reflect the vagotonic and sympatholytic effects of fentanyl on the baroreflex pathways.

Animals↗

PubMed1989

[Recovery of fluoride orally on the acid-etched tooth surface].

There are many reports concerning the recovery phenomenon of acid-etched enamel surfaces of teeth. Many studies of surface hardness, acid resistant properties, radiolucency, and surface morphology suggest that orally the acid-etched enamel reverts to a state nearly similar to that of the intact enamel before the acid etching. This study was conducted in order to verify the existence of the recovery phenomenon of fluoride on acid-etched enamel, because the surface layer of a high fluoride concentration is removed from the surface enamel by the acid etching. The deciduous upper central incisors of both sides were etched with phosphoric acid. The fluoride content of one incisor was measured immediately after the etching and that of the opposite incisor was also measured in vivo after 4 weeks, during which period no special fluoride was used. The fluoride content of the tooth surface in the mouth after 4 weeks significantly increased by about 50 ppm, when compared to that immediately after the acid etching. No significant relationship was found between the fluoride increase and the fluoride concentration of the patients' saliva and drinking water which were the probable supply sources of fluoride for the teeth. No relationship was found between the fluoride increase and the number of second deciduous molars with defects or fillings, which was counted as a measure of the patient's susceptibility to caries.

Acid Etching, Dental↗

PubMed1989

[Anesthetic management of elderly patients in open heart surgery].

In the National Cardiovascular Center, 46 patients whose ages were above 70 underwent open heart surgery from 1977 to 1986. Twenty of them received AC bypass and 5 had repair of the rupture of ventricular septum or left ventricular aneurysm. Among them 2 had also insertion of left ventricular assist device because of acute myocardial infarction (MI). Eighteen underwent mitral and/or aortic valve replacement. The other 3 were operated on because of atrial myxoma etc. Preoperatively, in ischemic heart disease group, due to resultant heart failure, one third of the patients were given catecholamines. In valvular heart disease group, angina pectoris and old MI were also common. Beside arrhythmias, respiratory complications, renal dysfunction and diabetes mellitus, neurological complications such as brain infarction were prominent in both groups. Hospital mortality was 15% in AC bypass group, 40% in acute MI group and 11.1% in VHD group. In 36 patients who left hospital, mean NYHA class improved after operation. The mortality rate and symptomatic improvement demonstrate that cardiac surgery can be performed with acceptable risk in elderly patients. Anesthesiologists should manage them carefully, considering the problems stated above.

Aged↗