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Biomedical subjects

R Ochiai

Publications and source records attributed to R Ochiai.

At least 37 records · Page 2Linked to original sources
PubMed1996

[The effect of droperidol and sevoflurane on serotonin-induced bronchoconstriction in dog].

Serotonin is a potent bronchoconstrictor, but the site of bronchoconstriction has not been determined. The present study was performed in dogs to clarify the site of bronchoconstriction induced by serotonin as well as to clarify the bronchodilating effect of droperidol and sevoflurance on the serotonin-induced bronchoconstriction by means of deflation flow-volume curve (DFVC) method, passive expiratory flow volume curve (PEFVC) method and respiratory system impedance measurement by forced oscillation method. Infusion of serotonin (60 micrograms.kg-1.min-1) induced a significant decrease in maximal expiratory flow at 10% of maximal expiratory volume (DEF10) by DFVC method and a significant increase in respiratory system impedance (Z). After droperidol (0.1 mg.kg-1) injection, DEF10 and Z returned to the control level and they remained unchanged even after the termination of serotonin infusion. Respiratory system compliance and resistance by PEFVC were unchanged by both serotonin and droperidol infusion or sevoflurane. Inhalation of 5% sevoflurane during serotonin infusion caused no significant change in DEF10. These findings indicate that serotonin-induced bronchoconstriction involves the small airway as well as the large airway. It is suggested that droperidol reversed serotonin-induced small airway constriction probably due to the antagonism of serotonin receptor in the airway. Bronchodilating effect of sevoflurane is probably limited in the small airway constricted by serotonin.

Anesthetics, Inhalation↗
PubMed1995

[Air pollution by sevoflurane in operating room and serum and urine inorganic fluoride of anesthetists].

Since lower blood-gas partition coefficient of sevoflurane provides rapid induction and emergence from anesthesia, sevoflurane has been used widely for inhalational anesthesia. However, because higher minimum alveolar concentration of sevoflurane requires a large dosage of anesthetic than other volatile anesthetics, air pollution with sevoflurane in the operating room might be of great concern. Anesthetists may keep inhaling the low concentration of anesthetics every day, even though scavenging system is equipped in the operating room. The purpose of this study is to evaluate the effects on anesthetists of the low concentration of anesthetics by measuring the inorganic fluoride concentration in the urine and serum of anesthetists and operating room nurses. Healthy 29 anesthesiologists and two operating room nurses were studied. Informed consent was obtained. Inorganic fluoride ions in the serum and urine were measured. Simultaneously sevoflurane concentration in operating room was measured in three operating rooms, at two places in the corridor and in the recovery room. Sevoflurane concentrations in three operating rooms were 1.22 ppm, 2.13 ppm and 6.05 ppm respectively. Concentration in the recovery room was 0.544 ppm. Serum and urine concentrations of inorganic fluoride were 1.1 +/- 0.1 mumol.l-1 and 36.2 +/- 17.1 mumol.l-1, respectively (mean +/- SD). Serum concentration of inorganic fluoride was within normal ranges. Although it is possible that fluoride concentration in urine is influenced by urine volume and a half of fluoride deposits in bone, no abnormal values in urine were found in this study. These results suggest that long term exposure to low concentration of sevoflurane and isoflurane causes no significant increase in their metabolites in operating room staffs.

Adult↗
PubMed1995

[Effects of nitrous oxide on electroencephalographic activity during sevoflurane anesthesia: a zero-crossing analysis].

We have investigated the influence of nitrous oxide (N2O) on central nervous system (CNS) during sevoflurane anesthesia by using zero-crossing method of EEG in 31 patients. The study was divided into three parts: Study 1 (n = 18), Study 2 (n = 6) and Study 3 (n = 7). (Study 1) After induction of anesthesia, sevoflurane 1.0 % in oxygen (O2), and sevoflurane 1.0 % with 67 % N2O in O2 were given to the patients sequentially in a random fashion, and EEG was recorded. (Study 2) Sevoflurane 1.7 % in O2, and sevoflurane 0.7 % with 67 % N2O in O2, which were considered to be the same anesthetic depth (= sevoflurane 1 MAC), were inhaled, and EEG was recorded in the same manner as in the study 1. (Study 3) We compared the effects of N2O on EEG during intravenous administration of fentanyl and midazolam with 67 % N2O, and without N2O, and EEG was recorded in the same manner. In all studies, percentage of each frequency range (delta, theta, alpha, beta) and average frequency were calculated by zero-crossing method. During sevoflurane anesthesia, the EEG activity was decelerated with N2O, depending on minimum alveolar concentration (MAC). But there were no significant changes in EEG activity of the patient with and those without N2O during intravenous anesthesia. We concluded that the influences of N2O on CNS can be evaluated by quantitative analysis of EEG.

Adult↗
PubMed1993

Contribution of rib cage and abdominal movement to ventilation for successful weaning from mechanical ventilation.

In order to test the hypothesis whether the breathing pattern is helpful in predicting weaning outcome in patients being weaned from mechanical ventilation, 38 patients who underwent operation for esophageal cancer were evaluated at weaning from mechanical ventilation (19 unsuccessful weanings, group U, and 19 successful weanings in age-matched patients, group S). Since all patients initially fulfilled our weaning criteria, ventilatory parameters such as tidal volume, respiratory frequency, minute ventilation, and arterial blood gas analysis showed no significant differences between the groups. The breathing pattern was registered quantitatively by means of respiratory inductive plethysmography at 3 cmH2O (0.3 kPa) of CPAP prior to weaning. The contribution of rib cage movement to tidal volume (%RC) was significantly greater in group U than in group S (P < 0.05). Indeed, 84% of the patients in group S showed %RC less than 50%, compared to only 16% of the patients in group U (P < 0.05). The results suggest that the breathing pattern is one important factor in predicting the outcome of weaning in patients after thoraco-abdominal surgery. Diaphragmatic fatigue is suspected to be the mechanism for the increase in the RC component in patients with unsuccessful weaning outcome.

Abdomen↗
PubMed1993

[A case of massive hemorrhage associated with the removal of longstanding intrabronchial foreign body].

A 46 year old male patient was admitted with fever and cough. A chest X-ray film revealed a foreign body shadow of a denture fragment in the right intermediate bronchus that he had swallowed one year and half ago. Rigid bronchoscopy was used to remove the foreign body under general anesthesia. During the procedure, massive hemorrhage occurred from bronchus, and the foreign body was not removed successfully and the patient sustained near cardiac arrest. Postoperatively, he recovered from the near fatal condition with support of mechanical ventilation in ICU for several days. After one month, pulmonary angiography was performed and it revealed the transfiguration of pulmonary artery and other vessels close to the foreign body. Granular tissue around the foreign body was observed by preoperative bronchoscopy. Disruption of such vessels and granular tissue by rigid and forced fiberscopy was suspected to have caused the massive bleeding. Later, the denture fragment was successfully removed by right thoracotomy. We should take this complication into consideration and preoperative fiberoptic bronchoscopy and pulmonary angiography may be beneficial to the anesthetic management of such patients.

Anesthesia, General↗
PubMed1993

[Changes of peripheral airways through mechanical ventilation in acute respiratory failure].

To evaluate the morphologic changes in the peripheral airways associated with positive pressure ventilation, fine fiberoptic bronchoscopy (1.8 mm outer diameter) was performed in 12 patients who had no history of prior pulmonary failure. In 19 examinations, the main morphologic findings were paleness and bronchial dilatation in the peripheral airways where increased secretions, pigmentation and stenosis or collapse were also observed. Patients with bronchial dilatation had longer periods of mechanical ventilation (17 +/- 8 days) compared to those without dilation (10 +/- 5 days). The structural destruction in the peripheral airways observed in patients on prolonged positive pressure mechanical ventilation suggests that barotrauma may be more widespread than previously recognized.

Acute Disease↗
PubMed1993

MR imaging of anomalous lobes of the liver.

Four patients with anomalous lobes of the liver were observed at MR imaging. In one patient the anterior segment of the right hepatic lobe was absent and in 3 patients the left hepatic lobe was anomalous. The hepatic vasculature supporting the information of the anomalous hepatic lobes was well observed in all patients.

Congenital Abnormalities↗
PubMed1993

[The effects of anesthetic techniques and insufflating gases on ventilation during laparoscopy].

The present study was performed to clarify the influences of anesthetic methods and insufflating gases on arterial blood gas and ventilation during laparoscopy. Forty five women undergoing laparoscopy for gynecological procedure were studied after dividing into four groups; general anesthesia with control ventilation or epidural anesthesia with spontaneous breathing, plus insufflation with carbon dioxide (CO2) or nitrous oxide (N2O). After CO2 insufflation, PaCO2 increased significantly in the patients who were mechanically ventilated, but not in the patients breathing spontaneously. After N2O insufflation, the decrease in tidal volume (VT) and the increase in VD/VT were significant, but minute ventilation was well maintained by the compensatory increase in respiratory frequency during spontaneous breathing. On the other hand, after CO2 insufflation VE and VD/VT increased significantly without any change in VT. PaO2 decreased significantly after both insufflation and Trendelenburg tilt in all groups, probably secondary to the decrease in functional residual capacity. These findings suggest that during laparoscopy, ventilation could be well maintained by spontaneous breathing, although the increase in VD/VT and costal breathing indicate the increase in respiratory work load. We recommend that ventilation and oxygenation should be closely monitored during laparoscopy to avoid hypercapnia and hypoxia.

Adolescent↗
PubMed1992

Improved PCO2 monitoring during high frequency jet ventilation.

During high frequency jet ventilation (HFJV), it has been shown that Pa(CO)(2) can be predicted by capnography when the frequency was temporarily reduced to obtain a steady expiratory CO(2) tension (P et(CO)(2)). The influence of the sampling site of expiratory gas in the airway and the driving pressure of the ventilator on the difference between Pa(CO)(2) and P et(CO)(2) was investigated in ten adult patients who underwent general anesthesia. During HFJV (frequency: 100 bpm, inspiratory duty cycle; 30%), its frequency was temporarily reduced to 10 bpm in twelve different condition; i.e., 3 different driving pressures (Pd; 20, 30, and 40 psi) at 4 different sampling sites (d; 0, 2, 5, and 10 cm in the endotracheal tube). Both P et(CO)(2) and Pa(CO)(2) were measured simultaneously, and their difference was evaluated by using Student's t-test. The difference between Pa(CO)(2) and Pmax(CO)(2) (the maximum P(CO)(2) value in the airway during exhalation) was minimal, when Pd was greater than 30 psi, and d was greater than 5 cm. The present study suggests that better prediction of Pa(CO)(2) can be done by P et(CO)(2) during HFJV, when d and Pd were set as large as possible to obtain stable expiratory P(CO)(2) curve.

Journal Article↗
PubMed1992

Evaluation of gastric tube with esophageal thermister (Thermosump).

The accuracy and the feasibility of esophageal temperature measured by a new gastric tube. Thermosump, which is incorporated with a esophageal thermister, was evaluated in anesthetized dogs (n = 6) and men (n = 59). In dogs, esophageal temperature measured by Thermosump was correlated well with the temperatures measured by the conventional esophageal thermister, and also by the pulmonary artery catheter (r = 0.98, 0.98, respectively). In anesthetized men, correlation between esophageal temperature by Thermosump and rectal, or bladder temperature was good during surgery of extremities (r = 0.81, 0.80, respectively). But during abdominal surgery, correlation between esophageal and bladder temperature was relatively poor (r = 0.50). Insertion of the tube, and suction of gastric fluid through the tube were easy without any complication. This newly developed gastric tube with a esophageal thermister was safe, and useful for measuring esophageal temperature.

Journal Article↗
PubMed1992

Differential sensitivity to halothane anesthesia of the genioglossus, intercostals, and diaphragm in kittens.

Recent studies in humans and animals have indicated that different inspiratory muscles have different sensitivities to respiratory depressants. The sensitivity of inspiratory muscles during early growth and development relative to that in adults of the same species, however, has not been studied. We therefore studied the activity of the diaphragm, the external intercostals, and the genioglossus by means of electromyography and its moving time average with different concentrations of halothane in seven 2-mo-old kittens. The kittens spontaneously breathed 1.0%-2.0% halothane in oxygen while PaCO2 was maintained at about 60 mm Hg by adding CO2 to the inspired gas as needed. Muscle activity was evaluated in terms of the peak height of the moving time average. Activity at 1% halothane was used as the control measurement because measurements at zero inspired concentrations of halothane could not be obtained without sedation, which is known to depress respiratory muscle activity. Halothane anesthesia significantly (P less than 0.01) decreased phasic inspiratory activity of the inspiratory muscles in a dose-dependent fashion. Genioglossal activity was completely abolished at 1.5% and 2.0% halothane. By contrast, in our previous study in adult cats under nearly identical experimental conditions, the phasic genioglossal activity was depressed but present even at 3.0% halothane. The degree of depression at 1.5% and 2.0% halothane was least in the crural diaphragm (71.8% +/- 5.8%, 66.6% +/- 4.5% of control, respectively), intermediate in the intercostals (68.9% +/- 9.6%, 35.4% +/- 8.8%), and greatest in the genioglossus (0.0%, 0.0%).(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1992

Serum and urinary inorganic fluoride concentrations after prolonged inhalation of sevoflurane in humans.

Serum and urinary concentrations of inorganic fluoride were measured before and after sevoflurane anesthesia in 10 patients without renal disease, who were scheduled for surgery lasting 13.4 +/- 0.9 h (mean +/- SE). The mean concentration of serum inorganic fluoride reached a maximal value of 42.5 +/- 4.5 mumol/L at the end of anesthesia. However, 5 of 10 patients had serum inorganic fluoride concentrations that exceeded 50 mumol/L (i.e., the nephrotoxic dose). A positive correlation was found between serum inorganic fluoride concentration and anesthetic dose. The largest urinary excretion of inorganic fluoride was 1804 +/- 378 mumol/day in the first postoperative day and rapidly decreased thereafter. We concluded that lengthy sevoflurane anesthesia created serum inorganic fluoride concentrations that could influence renal function, although nephrotoxicity was not demonstrated in our biochemical study.

Aged↗