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Biomedical subjects

H Toyooka

Publications and source records attributed to H Toyooka.

At least 37 records · Page 2Linked to original sources
PubMed2001

[Anesthetic management for left ventricular assist device implantation in patients waiting for heart transplantation].

We report the anesthetic management of patients with dilated cardiomyopathy who underwent left ventricular assist device implantation (LVAD). Anesthesia was induced and maintained with midazolam and fentanyl. Transesophageal echocardiography (TEE) and a PA catheter were useful for hemodynamic monitoring and management of the patients. Furthermore, TEE is useful for the early detection of inflow of the air which is absorbed by negative pressure derived from high LVAD support pressure. On starting LVAD support, evaluation of right ventricular function and treatment for right ventricular failure were important and necessary for the patients. Added to conventional therapy using catecholamines, inhaled nitric oxide may provide a favorable effect for right ventricular failure.

Adult↗
PubMed2001

[Dose-response study of preincisional buprenorphine on emergence time and postoperative analgesic requirement in patients anesthetized with sevoflurane].

The effect of intravenous buprenorphine on emergence time from sevoflurane anesthesia and postoperative analgesic requirement was evaluated after otolaryngeal surgeries. Forty-five patients were randomly assigned to one of three treatment groups (n = 15 each): Control-group received saline as a control; 2 micrograms-group received buprenorphine 2 micrograms.kg-1; and 4 micrograms-group received buprenorphine 4 micrograms.kg-1, respectively. Study drug was administered intravenously at the induction of general anesthesia. Anesthesia was maintained with sevoflurane (1.5%) and nitrous oxide (66%) in oxygen. The pain score, postoperative analgesic requirement, and incidence of nausea and/or vomiting were examined. The emergence times were 16.4 +/- 3.5, 14.7 +/- 5.2, and 17.8 +/- 7.7 min [mean +/- SD], in the control-group, the 2 micrograms-group, and the 4 micrograms-group, respectively. There were no differences among the groups in term of the end-tidal sevoflurane concentration immediately before tracheal extubation. In the control-group, the 2 micrograms-group, and the 4 micrograms-group, 10, 1, and 3 patients, requested additional analgesics during the first 24 hours after surgery, respectively (control-group vs. 2 micrograms-group and 4 micrograms-group, P < 0.05). Nausea and vomiting occurred more frequently in the 2 micrograms-group and the 4 micrograms-group. We conclude that buprenorphine (2 or 4 micrograms.kg-1) reduced analgesic requirement during the first 24 hours after surgery without delaying emergence from sevoflurane anesthesia.

Adult↗
PubMed2001

[Pulmonary edema in a child following laryngospasm triggered by a laryngeal mask airway during emergence from anesthesia].

A 9-year-old boy underwent biopsy of the tumor at the external auditory meatus under general anesthesia with a laryngeal mask airway(LMA). During emergence from anesthesia, laryngospasm with marked inspiratory effort and cyanosis occurred. The LMA was removed and the patient was orotracheally intubated following vecuronium administration. In spite of controlled ventilation with 100% oxygen, oxygen saturation remained at low 90s and pink frothy sputum appeared in the tracheal tube. We suspected negative pressure pulmonary edema and treated him with mechanical ventilation with positive end-expiratory pressure. Seventeen hours later the pink frothy sputum decreased and he was extubated. Laryngospasm during emergence from anesthesia with an LMA can induce negative pressure pulmonary edema, especially in pediatric patients.

Anesthesia Recovery Period↗
PubMed2001

[Change of cross-sectional area of the right internal jugular vein: effect of Trendelenburg position and valsalva maneuver].

To compare the effect of Valsalva maneuver and 10 degrees Trendelenburg position on the right internal jugular vein (RIJV), we measured RIJV cross-sectional area using ultrasound imaging during these procedures. The study group consisted of 13 normal healthy volunteers (6 males, 7 females, aged 25-47) with no history of neck surgery or right internal jugular vein (RIJV) puncture. All ultrasound images were obtained at the level of the cricoid cartilage. The subjects were positioned supine, and the measurements were taken with the subjects supine, under Valsalva maneuver, and under 10 degrees Trendelenburg tilt position. The cross-sectional areas of the RIJV during Valsalva maneuver and 10 degrees Trendelenburg position compared to those with supine position were 314 +/- 162%, and 192 +/- 96%, respectively. We conclude that both procedures increase cross-sectional area of IRJV significantly and in this respect Valsalva maneuver is more effective than Trendelenburg position.

Adult↗
PubMed2000

Advancement of the mandible facilitates nasal breathing in human subjects sedated with midazolam.

PURPOSE: To determine how anterior advancement of the mandible (ADM) affects spontaneous breathing through the nasal route in healthy human volunteers sedated with intravenous midazolam. METHODS: In four subjects who exhibited nasal breathing during midazolam sedation (intravenous dose: 0.09+/-0.02 mg x kg(-1), mean +/- SD), we measured respiratory rate (RR), peak nasal inspiratory airflow rate (V(nIpeak)) peak nasal expiratory airflow rate (V(nEpeak), duty ratio (Ti/Ttot) and nasal resistance (Rn) before and after ADM. Nasal resistance was calculated by dividing the difference between nasal mask and oropharyngeal pressure by airflow rate at peak nasal inspiratory airflow. RESULTS: The RR, V(nIpeak), and V(nEpeak) increased following ADM (P<0.001, respectively). On the contrary, Ti/Ttot decreased after ADM (P<0.001). Consequently, ADM decreased Rn from 30.4+/-40.8 to 5.0+/-5.6 (cm H2O x l(-1) x sec(-1)) (mean +/- SD) (P<0.001). In these four subjects, no respiratory airflow was observed through the oral route before and after ADM. CONCLUSION: Advancement of the mandible decreases nasal resistance, thereby facilitating spontaneous breathing through the nasal route in normal humans sedated with midazolam.

Adult↗
PubMed2000

Modifications of the hemodynamic consequences of theophylline intoxication with landiolol in halothane-anesthetized dogs.

PURPOSE: To examine the effect of landiolol (ONO-1101), a new ultra-short acting, highly selective beta1 blocker, on hemodynamic response to acute theophylline intoxication in anesthetized dogs. METHODS: Thirty-four dogs were studied during halothane anesthesia. Aminophylline (50 mg x kg(-1) over 20 min followed by infusion at 1.75 mg x kg(-1) x hr(-1)) was administered as a model of acute theophylline intoxication. Dogs were randomly enrolled into four landiolol groups (0, 1, 10, 100 microg x kg(-1) x min(-1)) to treat tachyarrhythmias. Hemodynamic variables, heart rate (HR), systemic blood pressure (SBP), pulmonary artery pressure, pulmonary artery occlusion pressure, and cardiac output (CO) were measured along with plasma concentrations of theophylline, epinephrine, and norepinephrine. RESULTS: After 60 min, plasma concentration of theophylline reached 46.6+/-4.0 (mean +/- SD) microg x ml(-1), HR increased from 129+/-21 to 193+/-27 bpm (P<0.0001) and CO increased from 1.6+/-0.5 l x min(-1) to 2.1+/-0.4 l x min(-1) (P<0.0001), whereas SBP decreased from 139+/-25 to 121+/-25 mm Hg (P<0.0001), with decreasing systemic vascular resistance. After intoxication, plasma epinephrine concentration increased from 125 +/-112 to 325+/-239 pg x ml(-1) (P<0.0001), and norepinephrine concentration from 103+/-61 to 133+/-61 pg x ml(-1) (P<0.0011). Landiolol 10 microg x kg(-1) x min(-1) decreased HR to pre-intoxication level, whereas HR returned to the intoxication baseline by 30 min after cessation of landiolol infusion. CONCLUSIONS: Landiolol controlled tachyarrhythmias associated with theophylline toxicity. The optimal effective dose of landiolol was 10 microg x kg(-1) x min(-1).

Adrenergic Agonists↗
PubMed2000

Effect of xenon on diaphragmatic contractility in dogs.

PURPOSE: This study was undertaken to examine the effect of xenon on diaphragmatic contractility in pentobarbitone- anesthetized, mechanically ventilated dogs. METHODS: Twenty-one dogs were randomly allocated to three groups (n=7 of each): Group I received oxygen 100%; Group II received xenon 30% in oxygen; Group III received xenon 60% in oxygen. Diaphragmatic contractility was assessed by measuring transdiaphragmatic pressure (Pdi) generated during supramaximal stimulation of phrenic nerves at the neck at low-frequency (20-Hz) and high-frequency (100-Hz) stimulation, after maintaining 60 min of stable condition. RESULTS: With inhalation of xenon at two different concentration (30% and 60%), no changes were observed in Pdi at either concentration. There was no difference in Pdi among the three groups. CONCLUSION: Increasing the concentration of xenon to 60% has no effect on diaphragmatic contractility in dogs. This suggests that xenon may be used safely as an anesthetic with respect to respiratory muscle function.

Anesthetics, Inhalation↗
PubMed2000

Flumazenil abolishes midazolam-induced increase in the work of nasal breathing.

PURPOSE: To evaluate the effects of midazolam sedation followed by flumazenil antagonism on the work of nasal breathing in normal humans. METHODS: We measured minute ventilation through the nasal route, respiratory frequency, nasal resistance (Rn) and the work of nasal breathing under three conditions: awake, during midazolam sedation, and after flumazenil antagonism in eight healthy human subjects. A custom-made, partitioned face mask enabled nasal and oral airflow to be measured separately. To calculate Rn and the work of nasal breathing, nasal mask and oropharyngeal pressure was also measured. RESULTS: Total resistive work spent on the upstream segment of the nasal route per minute (Wn) (J x min(-1)) was greater during midazolam sedation (3.6 +/- 2.9) than while awake (1.6 +/- 0.9) and after flumazenil antagonism (1.7 +/- 0.6), respectively (mean +/- SD) (P < 0.05). Total resistive work spent on the upstream segment of nasal breathing (WnNnE) (JxL(-1)) increased from 0.31 +/- 0.14 to 0.75 +/- 0.61 after midazolam administration (P < 0.05) and decreased to 0.31 +/- 0.10 after flumazenil. Following midazolam administration, a strong correlation was observed between changes in WnNnE and changes in Rn r = 0.852, P < 0.0001), whereas there was no correlation between changes in Wn and changes in Rn r = 0.159, P = 0.279). CONCLUSION: The work of breathing spent on the upstream segment of the nasal route increases during midazolam sedation and returns to baseline after flumazenil antagonism.

Adult↗
PubMed2000

Different effects of olprinone on contractility in nonfatigued and fatigued diaphragm in dogs.

PURPOSE: To evaluate the effects of low-dose olprinone, a phosphodiesterase III inhibitor, on contractility and its mechanism in nonfatigued and fatigued diaphragm in dogs. METHODS: Thirty six pentobarbitone-anesthetized dogs were studied. In Group Ia (n=6), animals without fatigue, received no study drug. In Group Ib (n=6), dogs were given a bolus injection (10 ug x kg(-1)) followed by continuous infusion (0.1 microg x kg(-1) x min(-1)) of olprinone. In Groups IIa, IIb, and IIc (n=8 each), diaphragmatic fatigue was induced by intermittent supramaximal bilateral electrophrenic stimulation at a frequency of 20-Hz applied for 30 min. After producing fatigue, Group IIa received no study drug; Group IIb was infused with olprinone (10 ug x kg(-1) loading dose plus 0.1 microg-kg(-1) min(-1) maintenance dose); Group IIc was infused with nicardipine (5 microg x kg(-1) x min(-1)) during olprinone administration. Diaphragmatic contractility was assessed by transdiaphragmatic pressure (Pdi). RESULTS: No difference in Pdi was observed between Groups Ia and Ib. After fatigue, in Groups IIa, IIb, and IIc, Pdi at low-frequency (20-Hz) stimulation decreased from prefatigued (baseline) values (P < 0.05), whereas there was no change in Pdi at high-frequency stimulation (100-Hz). In Group IIb, during olprinone administration, Pdi at both stimuli increased from fatigued values (P < 0.05). In Group IIc, the augmentation of Pdi to each stimulus in fatigued diaphragm by olprinone was abolished with an infusion of nicardipine. CONCLUSION: Low-dose olprinone does not affect contractility in nonfatigued diaphragm, but increases contractility in fatigued diaphragm via its effect on transmembrane calcium movement in dogs.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed2000

Effects of oral clonidine premedication on side effects of intravenous ketamine anesthesia: a randomized, double-blind, placebo-controlled study.

STUDY OBJECTIVE: To determine the effects of oral clonidine premedication on hemodynamic changes during the entire course of ketamine anesthesia and incidence of postoperative adverse reactions. DESIGN: Randomized, prospective, double-blind, placebo-controlled study. SETTING: Department of Anesthesiology, University of Tsukuba Hospital, Ibaraki, Japan. PATIENTS: 39 ASA physical status I and II patients undergoing superficial surgeries. INTERVENTIONS: Placebo, clonidine 2.5 micrograms/kg, and clonidine 5 micrograms/kg groups received respective doses of oral clonidine 90 minutes prior to surgery. Anesthesia was induced with ketamine 2 mg/kg intravenously (i.v.), trachea was intubated, and anesthesia was maintained with 67% nitrous oxide, oxygen, and supplemental ketamine (1 mg/kg) when systolic blood pressure and heart rate (HR) exceeded 180 mmHg and 100 bpm, respectively. MEASUREMENTS AND MAIN RESULTS: In the clonidine 2.5 micrograms/kg group, HR response to tracheal intubation was significantly less, while in the clonidine 5 micrograms/kg group both mean arterial pressure and HR responses were significantly suppressed, compared with the placebo group. Intraoperative coefficients of variations of HR were significantly less in both clonidine groups than the placebo group. Incidence of nightmare and degree of salivation were significantly less in the clonidine 5 micrograms/kg group than in the placebo group. CONCLUSION: Oral clonidine 2.5 micrograms/kg and clonidine 5 micrograms/kg attenuates cardiostimulatory effects, while clonidine 5 micrograms/kg was associated with reduced incidence and severity of nightmare and salivation attributable to i.v. ketamine.

Administration, Oral↗
PubMed2000

Granisetron/dexamethasone combination for the prevention of postoperative nausea and vomiting after laparoscopic cholecystectomy.

Dexamethasone decreases chemotherapy-induced emesis when added to an antiemetic regimen. This study was undertaken to evaluate the efficacy of granisetron/dexamethasone combination for preventing postoperative nausea and vomiting (PONV) after lapIaroscopic cholecystectomy (LC). In a prospective, randomized, double-blind manner, 120 patients (83 females), aged 25-65 years, were assigned to receive granisetron 40 microg kg-1 alone or granisetron 40 microg kg-1 plus dexamethasone 8 mg (n=60 of each) intravenously immediately before the induction of anaesthesia. A standardized general anaesthetic procedure and postoperative analgesia were used. A complete response, defined as no PONV and no need for another rescue antiemetic, during 0-3 h after anaesthesia was 83% with granisetron and 98% with granisetron plus dexamethasone, respectively (P=0.008); the corresponding incidence during 3-24 h after anaesthesia was 83% and 98% (P=0.008). No clinically important adverse events were observed in any of the group. In conclusion, prophylactic therapy with granisetron/dexamethasone combination is more effective than granisetron alone for the prevention of PONV after LC.

Adult↗
PubMed2000

Pretreatment with oral clonidine attenuates cardiovascular responses to tracheal extubation in children.

This study was designed to evaluate the effects of diazepam and clonidine orally given preoperatively on cardiovascular responses to tracheal extubation in children. Fifty children, ASA physical status I, aged 4-10 years, undergoing minor elective surgery (inguinal hernia, phimosis) received orally, in a randomized, double-blind manner, diazepam 0.4 mg.kg-1 or clonidine 4 microgram.kg-1 (n=25 of each). These drugs were administered 105 min before an inhalational induction of anaesthesia. The same standard general anaesthetic technique was employed throughout. The maximum changes in heart rate (HR), systolic blood pressure (SBP) and diastolic blood pressure (DBP) were less in patients who had received clonidine than in those who had received diazepam (HR, 12 vs 24; SBP, 14 vs 26; DBP, 9 vs 16; mean, P < 0.05). In conclusion, compared to diazepam given orally, pretreatment with oral clonidine attenuates haemodynamic changes associated with tracheal extubation in children.

Administration, Oral↗
PubMed2000

Effects of a thromboxane receptor antagonist (NT-126) and a thromboxane synthase inhibitor (OKY-O46) on protamine-induced circulatory changes in dogs.

OBJECTIVE: To examine whether a thromboxane receptor antagonist, NT-126, or a thromboxane synthase inhibitor, OKY-046, prevents circulatory changes caused by protamine reversal of heparin and to evaluate the significance of thromboxane generation in the phenomena. DESIGN: Prospective, randomized, controlled, animal study. SETTING: A university research laboratory. PARTICIPANTS: Twenty-four adult mongrel dogs. INTERVENTIONS: According to the pretreatments, the animals were divided into 3 groups (n = 8 in each): (1) control (normal saline); (2) NT-126, 0.01 mg/kg; and (3) OKY-046, 1 mg/kg. Under general anesthesia, all animals were anticoagulated with intravenous heparin, 200 IU/kg, 5 minutes before the pretreatment. Five minutes after the pretreatment, protamine sulfate, 2 mg/kg, was administered intravenously over 10 seconds. Hemodynamic variables were recorded repeatedly until 60 minutes after the protamine. Plasma thromboxane B2 level was determined at baseline and 10 minutes after protamine injection. MEASUREMENTS AND MAIN RESULTS: The average values of mean arterial blood pressure and mean pulmonary artery pressure among the 3 groups in each period and values in each group over the study period were not significantly different. There was weak correlation between maximum percent increases in systolic pulmonary artery pressure or maximum percent decreases in systolic arterial blood pressure for 5 minutes after the protamine versus percent increases in plasma thromboxane B2 level. CONCLUSION: Neither NT-126 nor OKY-046 appears to be effective in preventing protamine-induced circulatory changes in this dog model, suggesting that thromboxane generation alone is not responsible for the phenomena.

Animals↗
PubMed2000

Reduction in standard MAC and MAC for intubation after clonidine premedication in children.

We examined the relative effects of different doses of oral clonidine on the MAC for endotracheal intubation (MACEI) and the MAC for skin incision (MAC) in children. We studied 90 children (15 in each group) (age range 2-8 yr, weight 10-27 kg, height 89-124 cm) who received one of three preanaesthetic medications: placebo (control), oral clonidine 2 micrograms kg-1, or oral clonidine 4 micrograms kg-1 100 min before anaesthesia. Anaesthesia was induced and maintained with sevoflurane in oxygen and air without i.v. anesthetics and neuromuscular relaxants. The end-tidal sevoflurane concentration was kept constant for > or = 15 min before tracheal intubation or skin incision. MACs were determined using Dixon's 'up-and-down method'. Mean (SD) MACEIs of sevoflurane were 2.9 (0.1)%, 2.5 (0.1)% and 1.9 (0.1)% (P < 0.05), and MACs were 2.3 (0.1)%, 1.8 (0.1)% and 1.3 (0.1)% (P < 0.05), respectively, in control, clonidine 2 micrograms kg-1 and clonidine 4 micrograms kg-1 groups. The MACEIs and MACs decreased dose-dependently. The MACEI/MAC ratio (1.4) was not affected by clonidine.

Adrenergic alpha-Agonists↗
PubMed2000

Ramosetron for preventing postoperative nausea and vomiting in women undergoing gynecological surgery.

UNLABELLED: In a prospective, randomized, double-blinded, placebo-controlled trial, we evaluated the efficacy of ramosetron at three different doses (0.15, 0.3, and 0.6 mg) for the prevention of postoperative nausea and vomiting (PONV) after gynecological surgery. One hundred twenty women, ASA physical status I or II, aged 21-63 yr, received IV either placebo or ramosetron 0.15, 0.3, or 0.6 mg (n = 30 of each) at the completion of surgery. A standard general anesthetic technique and postoperative analgesia were used. A complete response, defined as no PONV and no need for another rescue antiemetic, during 0-3 h after anesthesia occurred in 40%, 47%, 87%, and 90% of patients who had received placebo and ramosetron 0.15, 0.3, and 0.6 mg, respectively. Corresponding results during 3-24 h after anesthesia were 43%, 50%, 87%, and 90%, and 24-48 h after anesthesia were 50%, 53%, 90%, and 93% (P < 0.05). Patients who had received ramosetron 0.3 or 0.6 mg were satisfied compared with those who had received placebo (P < 0.05). There were no serious clinical adverse events caused by the study drug in any of the groups. In conclusion, ramosetron 0.3 mg is an effective antiemetic for preventing PONV during 0-48 h after anesthesia in female patients undergoing gynecological surgery. Increasing the dose to 0.6 mg provided no further benefit. IMPLICATIONS: This randomized, double-blinded, placebo-controlled trial in 120 women found the effective dose of ramosetron for preventing postoperative nausea and vomiting after gynecological surgery to be 0.3 mg.

Adult↗
PubMed2000

The awakening concentration of sevoflurane in children.

UNLABELLED: Sevoflurane is frequently used as a rapidly acting drug for the induction of anesthesia. We investigated the awakening concentration (MAC-awake) of sevoflurane in ASA physical status I children (age range 2-10 yr). We also investigated the effects of two different doses of clonidine (2 and 4 microg/kg) on the MAC-awake of sevoflurane. Subjects were randomly divided into three groups and received placebo (n = 24), clonidine 2 microg/kg (n = 17), or clonidine 4 microg/kg (n = 22) orally, 100 min before the induction of anesthesia. Sedation scores were estimated, by using a five-point scale, after entry into the operating room, and anesthesia was induced and maintained with sevoflurane in oxygen and balanced nitrogen, without an additional anesthetic. After surgery, end-tidal sevoflurane was decreased stepwise by 0.2% at 15-min intervals, a standardized verbal command was played to the patients, and the MAC-awake was determined. The MAC-awake of sevoflurane alone was 0. 78% +/- 0.24% (mean +/- SD), which decreased to 0.36% +/- 0.09% and 0.36% +/- 0.16% (both P <0.0001, compared with the control group) after premedication with the small and large doses of clonidine, respectively. The lack of any dose-response relationship might be explained by a plateau effect. IMPLICATIONS: The awakening concentration of sevoflurane in unpremedicated children was 0.78%. Oral clonidine premedication at a dose of 2 microg/kg reduced the awakening concentration to 0.36%. However, an additional decrease in this value was not observed after the administration of the larger dose of clonidine premedication (4 microg/kg).

Administration, Oral↗