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Biomedical subjects

O Kemmotsu

Publications and source records attributed to O Kemmotsu.

At least 145 records · Page 8Linked to original sources
PubMed1989

[Response of the cervical sympathetic activity to acute hypoxemia in dogs and its modification by volatile anesthetics].

Response of the cervical sympathetic activity (CSA) to acute hypoxemia was studied in dogs in the absence and in the presence of either halothane (H), enflurane (E), isoflurane (I) or sevoflurane (S). Multifiber potentials of CSA, EEG, heart rate (HR), arterial blood pressure (ABP) and arterial oxygen saturation (SaO2) were continuously monitored. CSA increased responding to acutely induced hypoxemia at a speed of -6 - 9% (SaO2).min-1. The response of CSA was estimated in two ways as a function of SaO2: The threshold was determined at the SaO2 level where CSA increased by 3% over the basal level and the gain was determined by the slope of CSA increase divided by the SaO2 span. They were 92% and -1.88 in the absence of volatile anesthetics, respectively. The threshold and the gain decreased markedly in the presence of various concentrations of volatile anesthetics. They were 89.2% and -1.16; 81% and -0.74; 84.2% and -1.16 and 86.2% and -0.94 with 1 MAC of H, E, I and S, respectively. The depressant effects of volatile anesthetics on the CSA responses to acutely induced hypoxemia can cause depressed control of the autonomic nervous system against hypoxemia and conceal the manifestation of clinical signs of hypoxemia.

Anesthetics↗
PubMed1989

[Power spectral analysis of heart rate and peripheral blood flow variations during total spinal anesthesia].

We evaluated the effect of total spinal anesthesia (TSA) on the heart rate and peripheral blood flow variations to evaluate if TSA could influence these parameters as indicators of autonomic nervous function (ANF). Four patients with intractable pain were treated by TSA by administration of local anesthetics (lidocaine or mepivacaine) into the C7-Th1 vertebral interspace. Power spectrum of heart rate before TSA showed three peaks; low (LO-FR, 0.04-0.095 Hz), mid (MID-FR, 0.095-0.15Hz) and high frequency areas (HI-FR, 0.15-0.3Hz). Spectral peaks of LO-FR and MID-FR disappeared during TSA (P less than 0.001). HI-FR area decreased to 3.3% of the control level (P less than 0.001). Mean peripheral blood flow was changed to 59.9% of the control level (not significant). However, peripheral blood flow variations of LO-FR decreased to 11.3% of the control level (P less than 0.001) after TSA. Furthermore, the vagal discharge disappeared promptly after TSA in dog. These results suggest that TSA depresses the vagal activity as well as the sympathetic activity innervating the cardiovascular system and therefore, heart rate and peripheral blood flow variations are totally eliminated. Thus, we conclude that heart rate and peripheral blood flow variations can serve as valid markers of ANF activity.

Anesthesia, Spinal↗
PubMed1989

Effects of halothane and enflurane on conduction velocity and maximum rate of rise of action potential upstroke in guinea pig papillary muscles.

Using standard microelectrode techniques, the effects of halothane and enflurane on the maximum rate of rise of action potential upstroke (Vmax) and conduction velocity of excitation were compared with those of fast sodium channel blockers in isolated guinea pig papillary muscles. Lidocaine and tetrodotoxin decreased the square of the conduction velocity in proportion to the decrease in Vmax. In contrast, halothane and enflurane only slightly affected Vmax, but decreased the conduction velocity in a concentration-dependent manner. These results suggest that these volatile anesthetics affect conduction velocity by a mechanism different from that of fast sodium channel blockers. Caution should be used when these anesthetics are administered to patients receiving class 1 antiarrhythmic agents or who have pre-existing intraventricular conduction disease.

Action Potentials↗
PubMed1988

Effects of halothane and calcium entry blockers on atrioventricular conduction-a comparative study of verapamil, diltiazem, and nifedipine.

The effects of halothane on AV nodal function were evaluated in dogs with verapamil, diltiazem, or nifedipine during atrial pacing using the technique of His-bundle electrocardiography. Fifty-one mongrel dogs were divided into six groups. Anesthesia was induced with ketamine 100 mg im. and thiamylal 25 mg/kg iv. The animals were intubated and mechanically ventilated at normocapneic levels. Anesthesia was maintained with 50% nitrous-oxide in oxygen with pancuronium 2 mg im. Dogs in groups I, III, and V were anesthetized with 0.8% halothane and 50% nitrous-oxide in oxygen. We observed interactions between halothane and intravenous administration of either verapamil 0.1 mg/kg, diltiazem 0.15 mg/kg, or nifedipine 0.01 mg/kg respectively. Dogs in groups II, IV, and VI were administered either verapamil, diltiazem, or nifedipine iv without halothane. There were prolongations of sinus cycle length (SCL) (414 +/- 10 to 542 +/- 19 msec.), atrium-His (AH) interval (73 +/- 3 to 97 +/- 5 msec.), and functional refractory period (FRP) of the AV-node (227 +/- 5 to 260 +/- 5 msec.) in halothane anesthesia in groups I, III, and V. There were more prolongations of these variables after iv administration of verapamil (SCL; 617 +/- 35, AH; 118 +/- 7, FRP of the AV node; 311 +/- 4) and diltiazem (SCL; 554 +/- 19, AH; 118 +/- 12, FRP of the AV node; 283 +/- 12) but no prolongations after nifedipine (SCL; 533 +/- 19, AH; 99 +/- 8, FRP of the AV node; 272 +/- 9). Comparing effects of calcium entry blockers with and without halothane in groups I and II, III and IV, or V and VI, there were additive depressing effects of halothane with either verapamil or diltiazem on AV nodal function. And there is a difference between the effects of nifedipine on SCL with and without halothane.

Journal Article↗
PubMed1988

Clinical evaluation of continuous venous oxygen saturation monitoring during anesthesia.

Clinical evaluation of continuous SvO2 monitoring during anesthesia was made in 14 surgical patients utilizing a fiberoptic reflectometry system combined with a pulmonary artery flow-directed balloon catheter. On-line values for SvO2 by the system were closely related to those obtained in vitro from a Radiometer ABL-300. There was a good correlation between changes of in vivo SvO2 and corresponding changes in cardiac index. We also observed that there was a significant correlation between SvO2 and oxygen extraction ratio. Our data indicate that continuous SvO2 monitoring during anesthesia can provide on-line information not only about hemodynamic state but also on oxygen transport.

Adult↗
PubMed1988

Can blood gas analysis indicate when mechanical ventilation should start in patients with acute myocardial infarction?

Arterial blood gas analysis of 69 patients with acute myocardial infarction were evaluated to provide a basis for respiratory care. Patients were divided into two groups: group A which received oxygen therapy only (n = 38) and group B which received oxygen therapy with mechanical ventilation (n = 31). The patients in group B were further divided into surviving cases (n = 14) and fatal cases (n = 17). On admission patients assigned to group B had lower PaO2 values than those placed in group A. In group B, there was no difference in the P/F value before mechanical ventilation of the surviving and the fatal cases, but the survivors demonstrated an improvement of the P/F value and an increase in cardiac index after mechanical ventilation. It may be reasonable to assume that a P/F value of less than 250 serves as an indicator for the initiation of mechanical ventilation. An increase in the P/F value after mechanical ventilation seems to be a valuable index to estimate prognosis in respiratory failure.

Blood Gas Analysis↗
PubMed1983

Haemodynamic effects of atracurium in surgical patients under nitrous oxide, oxygen and isoflurane anaesthesia.

The haemodynamic effects of atracurium were studied in 16 patients (ASA I and II) undergoing major surgical procedures under nitrous oxide, oxygen and isoflurane anaesthesia. Atracurium was administered in two doses 0.2 and 0.4 mg kg-1 in the presence of 1.25 MAC isoflurane in nitrous oxide and oxygen. There were no significant changes in mean arterial pressure, systemic vascular resistance or central venous pressure with either dose. There were statistically significant alterations in heart rate and cardiac index at the 10-min observation in those patients receiving atracurium 0.4 mg kg-1. These changes were deemed to be clinically unimportant in this group of patients. There was no indication of histamine release manifested in the form of allergic reaction or decrease in systemic resistance. It is concluded that those two doses of atracurium have no untoward side-effects on cardiovascular performance at least in this group of healthy patients.

Adolescent↗
PubMed1983

Intubation conditions after atracurium and suxamethonium.

Conditions for endotracheal intubation provided by different dose regimens of atracurium 0.4 mg kg-1 and 0.5 mg kg-1 were studied and compared with each other and with suxamethonium 1.0 mg kg-1. Intubation was attempted at 2.5, 2 min and 1.5 min following a bolus dose of atracurium, and 1 min following suxamethonium. Ease of intubation was rated excellent in 90-100% of all patients studied. Atracurium, when administered 5 min following recovery from a suxamethonium-induced block, had a significantly faster onset of neuromuscular blockade (P less than 0.01) than the onset observed following atracurium alone. Administration of atracurium 0.42 mg kg-1 3 min after an initial dose of 0.08 mg kg-1 of the drug produced a significantly more rapid onset of block when compared with a bolus dose of 0.5 mg kg-1 (P less than 0.02).

Adult↗
PubMed1982

Cardiocirculatory effects of prolonged administration of isoflurane in normocarbic human volunteers.

Effects of the prolonged administration of isoflurane on haemodynamics were studied in 17 healthy volunteers under normocarbic conditions. The anaesthetic was administered for 90 min at a constant alveolar concentration. Cardiac index was unchanged in the presence of decrease stroke volume index and increased heart rate. The mean arterial pressure decreased with parallel reductions in total peripheral resistance. Left ventricular work decreased. The left ventricular ejection time index increased marginally but significantly. Isoflurane caused no change in the pump performance of the heart but depressed the muscle performance.

Adult↗