Hideo Yamamura

GAS CHROMATOGRAPHIC ANALYSIS OF INHALATION ANESTHETICS IN WHOLE BLOOD BY AN EQUILIBRATION METHOD

A gas chromatographic procedure for the quantitative analysis of the inhalation anesthetics in blood was devised. A blood sample was equilibrated in 10 ml. or 20 ml. glass vial. After equilibration 1 ml. of the gas in the vial was introduced into a gas chromatograph and the anesthetic concentration in blood was measured from that in gas phase by means of a calibration curve prepared from appropriate standards. A thermal conductivity detector was used for the analysis of nitrous oxide, cyclopropane and ether, while a flame ionization detector was used for halothane, methoxyflurane and low concentration of ether. Concentrations in blood of inhalation anesthetics now available can be measured accurately by this method.

A Dose‐response Study with Dihydroergotoxine Mesylate in Cerebrovascular Disturbances

Basic pharmacologic evidences have suggested the effects of dihydroergotoxine mesylate (DEM) on neurotransmitters. In its clinical use, however, various therapeutic effects and side effects are observed when the dose is changed, because of the complexity of this compound and the delicate mechanism of neurotransmitters in the brain, especially when modified by aging and vascular lesions.

The effect of gas inflow on the regulation of CO2 levels with hyperventilation during anesthesia.

The authors describe a method by which a normal CO2 level may be achieved during hyperventilation, simultaneously regulating fresh gas flow rate (V l/min, ambient temperature) into an anesthesia circle system from which the carbon dioxide absorber has been removed. Using a tidal volume of 15 ml/kg and a respiratory rate of 16/min, PAco2 may be approximated as where Vco2 is calculated according to the formulas of Kleiber. In 35 patients studied, the PAco2 values observed agreed well with the calculated values when the latter were above 30 torr. With increases in V, observed values generally exceeded calculated values, indicating increasing fresh gas flow bypassing the patient.

Effects of Anesthetics on P onto-geniculo-occipital Waves from the Oculomotor Nucleus of the Cat

Effects of anesthetics and doxapram on pontogeniculo-occipital (PGO) waves from the oculomotor nucleus were studied in acute experiments in cats paralyzed by gallamine triethiodide. The anesthetic agents studied in the present experiment (thiopental, ketamine, Innovar, nitrous oxide, and halothane) decreased, while doxapram increased, the total number of PGO waves. As the doses of anesthetics increased, PGO waves were abolished, but they returned to control levels or below control levels when the concentrations of anesthetics were decreased. The results indicate that the anesthetics studied inhibit the activity of the central mechanism associated with the oculomotor system. PGO waves may prove a useful index of the level of anesthesia.

THE EFFECTS OF VENTILATION ON THE ABSORPTION AND ELIMINATION OF INHALATION ANAESTHETICS.

Among the various causes which influence absorption and elimination of inhalation anaesthetics are anaesthetic gas concentration, ventilation, diffusion and solubility of anaesthetics in the blood. In order to deepen anaesthesia, it is usual to increase the concentration of gas without paying much attention to ventilatory volume. To accelerate recovery from anaesthesia, however, it is a common practice to wash out the gas by ventilating the lung with high flows of oxygen. To find out the influence of ventilatory volume on absorption, inhalation anaesthetic agents have been administered with various tidal volumes by the non-rebreathing method, measuring the concentration of anaesthetics in arterial blood. This method also was used to find out the relationship between rate of elimination and ventilatory volume. EEG, ECG, arterial P C O ~ and arterial blood pH were observed at the same time. This study was carried out with 6% of ether in oxygen as a typical volatile agent and with 10% of cyclopropane in oxygen as a gaseous agent.

Nitrous oxide content in the operating suite.

Nitrous oxide (N2O) concentrations in the ambient atmosphere were measured by gas chromatography during surgical anesthesia. Levels in the recovery room were affected not only by the N2O content in the expiratory air of postanesthetic patients and personnel but also by N2O levels in the operating rooms. With the onset of N2O anesthesia in operating rooms, gases blow into all adjacent areas; while this level is relatively low, operating-suite personnel cannot escape some exposure to N2O.

THE SITE OF ACTION OF INNOVAR IN THE BRAIN

SummaryDeep sedation and a laissez faire attitude occurs in cats when Innovar is placed into the posterior hypothalamus, the centro-median thalamic nucleus and the ventropostero-lateral thalamic nucleus through precise stereotaxically implanted recording cannulae. This sedation persists in the presence of pin-prick stimulation as observed by the persistence of neocortical deactivation and hippocampal activation or seizures.Following the application of Innovar into the mesencephalic reticular and pontine reticular formations, no persistent behavioural or electroencephalographic evidence of sedation was observed in the presence of pin-prick stimulation.RésuméIl se produit une sédation profonde et une attitude de “laisser faire” chez les chats lorsqu’on introduit de l’Innovar dans l’hypothalamus postérieur, dans le noyau thalamique centro-médian, et dans le noyau thalamique ventro-postéro-latéral, à l’aide de canules enregistreuses implantées avec précision par une technique stéréotaxique. Cette sédation persiste en présence d’une stimulation par piqure d’épingle comme on l’a observé par la persistance de déactivation néocorticale et d’activation ou attaque de l’hyppocampe.A la suite d’application d’Innovar dans les formations réticulaires mésencéphaliques et dans les formations réticulaires protubérentielles, on n’a observé aucune évidence de sédation persistante ni dans la conduite générale ni dans l’électroencéphalographie, même après stimulation par piqure d’épingle.

Hidden Factor of Cardiac Arrhythmia During Light Anesthesia

Effects of anesthetics on cardiac arrhythmias during parasleep were investigated in four cats. Parasleep was still observed under light anesthesia (80 % nitrous oxide, 0.5 % methoxyflurane and 0.5 % halothane), and cardiac arrhythmias occurred. When the concentration of anesthetics was increased (1.0 % methoxyflurane, 1.0 % halothane), parasleep was never observed. Cardiac arrhythmias did not occur during deep anesthesia. Judging from these results, parasleep must be regarded as one of the etiological factors in the development of cardiac arrhythmias during light anesthesia.

CONTROL OF HYPERTENSION DURING ISOFLURANE OR SEVOFLURANE ANESTHESIA WITH CONTINUOUS INFUSION OF NICARDIPINE HYDROCHLORIDE

Abstract In a multicenter study, the efficacy and tolerability of nicardipine hydrochloride (NIC) were examined when the drug was used to control hypertension during isoflurane or sevoflurane anesthesia in patients with or without a preoperative history of hypertension. Retrospectively, the 124 study patients were divided into four groups: patients without (group 1) or with (group 2) a preoperative history of hypertension who received isoflurane anesthesia, and those without (group 3) or with (group 4) a preoperative history of hypertension who received sevoflurane anesthesia. NIC infusion was started when systolic pressure exceeded 160 mm Hg or 30% above the control value determined before the induction of anesthesia. The ability of NIC to control hypertension was analyzed for 30 minutes after starting the infusion. Arterial pressure, heart rate, and urine volume were examined in each group. Mean doses of NIC infused during the 30-minute study period in groups 1, 2, 3, and 4 were 2.23, 2.13, 2.43, and 2.19 μg · kg −1 · min −1 , respectively. There were no significant differences between the four groups in the amount of NIC infused. In the four groups, no significant changes were seen in heart rate, and blood pressure was effectively controlled (group 1: 149.5/86.4 mm Hg and 113.3/63.0 mm Hg before and after the 30-minute study period, respectively; group 2: 156.6/91.2 mm Hg and 118.2/71.0 mm Hg; group 3: 153.4/90.1 mm Hg and 119.0/71.1 mm Hg; and group 4: 160.6/98.7 mm Hg and 124.1/76.8 mm Hg). The final blood pressure measurements were considered within normal ranges for the patients studied. A decrease in blood pressure was slightly delayed in both sevoflurane groups (groups 3 and 4) and in the isoflurane group with a preoperative history of hypertension (group 2). While urine output tended to increase in all groups, a significant increase was found only in group 1 (from 0.019 ± 0.011 mL · kg −1 · min −1 before treatment to 0.087 ± 0.041 mL · kg −1 · min −1 after treatment). In conclusion, NIC was effective and well tolerated in controlling hypertension during isoflurane or sevoflurane anesthesia

The effect of pentobarbital sodium on the dorsal horn of the spinal cord

The effect of intravenously administered pentobarbital sodium on the activity of single unit in Rexed lamina V of the transected feline lumbar spinal cord was studied using an extracellular microelectrode recording technique. Pentobarbital sodium 1.0 mg·kg−1, 2.5 mg·kg−1, and 5.0 mg·kg−1 administered intravenously suppressed both the spontaneous and the evoked activity in Rexed lamina V cells, known to respond principally to noxious stimuli, in a dose-dependent manner. The maximum depression of cell activity occurred within 5 min after intravenous administration. The recovery of cell activity occurred within 70 min after intravenous administration of pentobarbital sodium. We conclude that pentobarbital sodium intravenously administered has a suppressive effect on single unit activity of cells in Rexed lamina V and probably has an analgesic effect. Its suppressive effect is dose-dependent.