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Biomedical subjects

H Toyooka

Publications and source records attributed to H Toyooka.

At least 145 records · Page 8Linked to original sources
PubMed1995

Effects of calcium channel blockers on circulatory response to tracheal intubation in hypertensive patients: nicardipine versus diltiazem.

We studied the circulatory responses to laryngoscopy and tracheal intubation in 37 hypertensive patients who received nicardipine 30 micrograms.kg-1 iv (Group N, n = 12), diltiazem 0.3 mg.kg-1 (Group D, n = 12) or saline placebo (Group C, n = 13) 60 sec before the initiation of laryngoscopy. Anaesthesia was induced with thiopentone 5 mg.kg-1 iv, and succinylcholine 2 mg.kg-1 iv was used to facilitate tracheal intubation after precurarization with vecuronium 0.02 mg.kg-1 iv. In patients in Group C heart rate (HR) increased from 79 +/- 14 (baseline) to 110 +/- 12 (P < 0.05) associated with tracheal intubation; mean arterial pressure (MAP) increased from 116 +/- 8 to 140 +/- 77 (P < 0.05) and rate-pressure product (RPP) increased from 13385 +/- 2393 to 21251 +/- 3883 (P < 0.05). The changes from baseline values in HR and RPP after tracheal intubation in Group D were less than those in Groups C and N (P < 0.05). The increase in MAP following tracheal intubation in Groups N and D was lower than that in Group C (P < 0.05). We conclude that, compared with nicardipine, administration of diltiazem iv is associated with less circulatory response to tracheal intubation in hypertensive patients.

Adult↗
PubMed1995

Post-tetanic burst count: a stimulating pattern for profound neuromuscular blockade.

The purpose of this study was to compare the pattern of recovery from vecuronium 0.07 mg.kg-1 induced neuromuscular blockade using post-tetanic burst count (PTBC)-(three short tetanic bursts of 0.2 msec duration every 20 msec given every second following a tetanus), and post-tetanic count (PTC)-(0.2 msec single twitch stimuli given every second following a tetanus) using an accelerometer in 60 adult patients during nitrous oxide-oxygen-isoflurane anaesthesia. In addition, the relationship among PTBC, PTC, and T1 (the 1st response in the train-of-four (TOF) stimulation) was examined to investigate whether the PTBC had an advantage over the PTC or TOF for evaluating intense neuromuscular blockade. The PTBC was greater than PTC during the 15-35 min after the administration of vecuronium (unpaired t test with Bonferroni's correction, P < 0.05). Time to the return of PTB response was shorter than that of PTT (17.7 +/- 3.2 vs 22.7 +/- 3.7 min, unpaired t test, P = 0.0005). Time from the return of PTB to that of T1 was longer than the time from the return of PTC to that of T1 (13.3 +/- 2.6 vs 9.2 +/- 2.8 min, unpaired t test, P = 0.0003). At the return of T1, PTBC was greater than PTC (14.3 +/- 6.9 vs 9.4 +/- 2.3, unpaired t test, P = 0.0153). These results suggest that, using PTBC, a more profound level of neuromuscular blockade can be evaluated than that using PTC.

Adult↗
PubMed1995

Granisetron-dexamethasone combination reduces postoperative nausea and vomiting.

The prophylactic antiemetic efficacy of combined granisetron and dexamethasone was evaluated in a randomized double-blind manner in 88 patients undergoing general anaesthesia for major gynaecological surgery. Immediately after recovery from anaesthesia, patients received a single dose of either placebo (saline, n = 22), granisetron (20 micrograms.kg-1, n = 22), dexamethasone (8 mg, n = 22) or combined granisetron and dexamethasone (20 micrograms.kg-1 and 8 mg, respectively, n = 22) iv. The treatment groups were similar for patient demography, surgical procedures, anaesthetics administered and opioids given. Postoperatively, the frequency of nausea was 32%, 23%, 27% and 5% after administration of placebo, granisetron, dexamethasone and granisetron plus dexamethasone, respectively; the corresponding frequencies of vomiting were 23%, 23%, 23% and 5%. The incidence of adverse events postoperatively were not different among the groups. It is concluded that prophylactic administration of combined granisetron and dexamethasone is effective in preventing postoperative nausea and vomiting after anaesthesia.

Adult↗
PubMed1995

Post-tetanic burst: a new monitoring method for intense neuromuscular block.

A new stimulation pattern for evaluation of intense neuromuscular block (post-tetanic burst (PTB)) was compared with post-tetanic twitch (PTT) during spontaneous recovery from vecuronium-induced neuromuscular block. Thirty adult patients were allocated to two equal groups and we measured times from administration of vecuronium 0.1 mg kg-1 to return of PTB and PTT responses, and evoked responses to PTB and PTT stimuli. For PTB stimulation, a 50-Hz tetanus was applied at 50 mA for 5 s, and after a pause of 3 s, a 50-Hz burst stimulation was applied, consisting of three impulses at 50 mA. PTB stimuli were delivered every 5 min. Similarly, PTT consisted of a tetanus, a 3-s pause and one single twitch stimulation repeated every 5 min. Time to return of the PTB response was significantly shorter than that of PTT (mean 23.7 (SD 7.9) compared with 30.7 (7.0) min) (P = 0.0160), although evoked responses to PTB did not differ significantly from those of PTT throughout recovery from vecuronium-induced neuromuscular block. This study suggested that PTB was more sensitive in evaluating intense neuromuscular block than PTT.

Adult↗
PubMed1994

Clinical assessment of a continuous intraarterial blood gas monitoring system.

We evaluated the clinical performance of a continuous intraarterial blood gas monitoring (CIABG) system which includes a fluorometric intravascular sensor. Seventeen patients undergoing elective surgery were monitored perioperatively with the CIABG system (PB3300; Puritan Bennett, Carlsbad, CA). Conventional laboratory blood gas analyses (BGA) were performed simultaneously whenever indicated, and the values were compared with those obtained from the CIABG system. Monitoring time ranged from 24 to 72 hr. The biases (average error between PB3300 and BGA) of pH, PCO2 and PO2 were 0.003 pH unit, -2.8 mmHg, and 0.9 mmHg in the operating room (OR), and 0.005 pH unit, 3.9 mmHg, and 8.5 mmHg in the intensive care unit (ICU), respectively. The precision (standard deviation of the bias) of pH, PCO2 and PO2 were 0.030 pH unit, 2.1 mmHg, and 29.9 mmHg in the OR and 0.035 pH unit, 3.8 mmHg, and 14.7 mmHg in the ICU, respectively. Although the PB3300 system was clinically useful as a trend monitor, the system's precision and reliability were unacceptable for estimation of true blood gas values.

Adult↗
PubMed1994

Nicardipine enhances diaphragmatic fatigue.

The effects of nicardipine, a calcium channel blocker, on diaphragmatic fatigue were studied in 20 anaesthetized, mechanically ventilated dogs divided into two groups: control group (Group C, n = 10) and nicardipine group (Group N, n = 10). Diaphragmatic fatigue was induced by intermittent supramaximal electric stimulation to bilateral phrenic nerves at a frequency of 20 Hz for 30 min. In Group N, 5 micrograms.kg-1.min-1 nicardipine iv was infused continuously during this fatigue-producing period. Transdiaphragmatic pressure (Pdi) produced by electrical stimulation (10-100 Hz) of the phrenic nerves was used as an index of diaphragmatic contractility. After a fatigue-producing period, the Pdi in both groups decreased at low frequency (10-30 Hz) stimulation compared with pre-fatigue values (P < 0.05), whereas no change in Pdi was observed at high-frequency (50-100 Hz) stimulation. The decrease of Pdi at low-frequency stimulation was larger in Group N (P < 0.05). The integrated diaphragmatic electric activity (Edi) in both groups did not change at any frequency of stimulation throughout the experiment. We conclude that nicardipine enhances diaphragmatic fatigue.

Animals↗
PubMed1994

Reduction of postoperative nausea and vomiting with granisetron.

The antiemetic effects of granisetron, a selective 5-hydroxy-tryptamine type 3 receptor antagonist, on postoperative nausea and vomiting were studied and compared with placebo and metoclopramide in 60 patients undergoing general anaesthesia for major gynaecological surgery. The patients received a single i.v. dose of either granisetron (3 mg, n = 20) metoclopramide (10 mg, n = 20), or placebo (saline, n = 20) immediately after recovery from anaesthesia. The effects were assessed during the first three and the next 21 hr after recovery from anaesthesia by means of a nausea and vomiting score; 0 = no emetic symptoms, 1 = nausea, 2 = vomiting. The mean scores during 0-3 hr were 0.8, 0.1 and 0.1 after administration of placebo, metoclopramide and granisetron, respectively; the corresponding scores during 3-24 hr were 0.6, 0.5 and 0.1. The scores of the metoclopramide and the granisetron groups were different from the placebo group in the first three hours (P < 0.05). Although there were no differences in the scores during 0-3 hr between the metoclopramide and the granisetron groups, there were differences during 3-24 hr (P < 0.05). It is concluded that granisetron is superior to metoclopramide in the long-term prevention of postoperative nausea and vomiting after anaesthesia.

Adult↗
PubMed1994

Optimal anti-emetic dose of granisetron for preventing postoperative nausea and vomiting.

In order to determine the optimal effective dose of granisetron for preventing postoperative nausea and vomiting, the drug was administered in doses of either 20, 40 or 60 micrograms.kg-1. The efficacy of granisetron was evaluated in a randomized, double-blind comparison with placebo in 100 patients undergoing general anaesthesia for major gynaecological surgery. The patients received a single dose of either granisetron or placebo (saline) iv immediately after recovery from anaesthesia. The effects were assessed during the 24 hr after recovery from anaesthesia by means of a nausea and vomiting score; 0 = no emetic symptoms, 1 = nausea, 2 = vomiting. The treatment groups were similar for patient characteristics, surgical procedures and anaesthetics administered. The mean scores were 0.7, 0.6, 0.2 and 0.2 after administration of placebo, granisetron 20, 40 and 60 micrograms.kg-1, respectively. Granisetron 40 micrograms.kg-1 was as effective as 60 micrograms.kg-1 and both resulted in reduction of the scores compared with placebo and granisetron 20 micrograms.kg-1 (P < 0.05). In conclusion, granisetron 40 micrograms.kg-1 is considered to be the appropriate dosage for preventing postoperative emesis after anaesthesia.

Adult↗
PubMed1994

Cutaneous iontophoretic application of condensed lidocaine.

The purpose of this study was to determine whether iontophoretic application of high concentrations of lidocaine, with the same current, would produce cutaneous local anaesthesia rapidly enough for clinical practice. Twenty healthy volunteers, 17 male and three female, were selected for study. After five-minute or ten-minute iontophoresis using lidocaine 4, 10, 20, 30, 50%, we assessed the response to pin prick with a 27-gauge sterile needle inserted to the depth of 2 mm at five random locations in the iontophoretically-stimulated area. Also, plasma lidocaine concentrations were measured in the venous blood samples which had been taken from three male subjects, at 3, 10, and 30 min after iontophoresis with lidocaine 50%. The pain score after five-minute iontophoresis was higher than that after ten-minute iontophoresis, using each concentration of lidocaine (P < 0.001), whereas the pain scores had no correlation with lidocaine concentration within five-minute and ten-minute iontophoresis groups, respectively (P: NS). On the other hand, plasma lidocaine concentration was < 1.0 micrograms.ml-1 in all samples. No side effects other than erythema were observed after iontophoresis using high concentrations of lidocaine up to 50%. These results showed that by increasing the lidocaine concentration of the applied solution up to 50%, the application time of iontophoresis cannot be reduced from ten to five minutes without losing analgesic effect, although iontophoresis itself can be performed with safety.

Administration, Cutaneous↗
PubMed1994

Post-tetanic count and single twitch height at the onset of reflex movement after administration of vecuronium under different types of anaesthesia.

We have studied post-tetanic count (PTC) and single twitch height at the onset of reflex movement to carinal stimulation after administration of vecuronium with five different types of anaesthesia. Seventy-five adult patients were allocated randomly to five groups of 15 patients each, to receive one of the following anaesthetics: neuroleptanaesthesia (fentanyl and droperidol) or 1 MAC of either halothane, isoflurane, enflurane or sevoflurane with 66% nitrous oxide in oxygen. During spontaneous recovery from vecuronium-induced neuromuscular block, the carina was stimulated with a suction catheter every 150 s. Single twitch heights at the onset of reflex movement were similar (2.0-2.7% of control values) between the five groups. In contrast, PTC at the onset of reflex movement to carinal stimulation differed (7.4-17.0) between groups.

Adult↗
PubMed1994

Effect of tetanic stimulation on subsequent train-of-four responses at various levels of vecuronium-induced neuromuscular block.

Tetanic stimulation influences subsequent neuromuscular responses. In addition, the tetanus-induced changes in neuromuscular responses differ according to the level of neuromuscular block at which tetanic stimulation is delivered. We studied the tetanus-induced effect on subsequent train-of-four (TOF) responses at various levels of vecuronium-induced neuromuscular block in 45 anaesthetized patients. Tetanic stimulation was applied when a twitch height of T1 returned to 25%, 50% and 75% of its control twitch height (T0) (groups 1, 2 and 3, respectively) after administration of vecuronium 0.1 mg kg-1. Maximum post-tetanic percentage increases in TOF responses in groups 1, 2 and 3 were 257 (SD 119)%, 107 (75)% and 68 (54)% for T1/T0 (P < 0.001 for group 1 vs 2; P < 0.001 for group 1 vs 3) and 535 (259)%, 421 (213)% and 292 (171)% for T4/T1 (P < 0.01 for group 1 vs 3), respectively. Durations of post-tetanic increases in TOF responses in groups 1, 2, and 3 were 52 (19) s, 37 (14) s and 32 (13) s for T1/T0 (P < 0.05 for group 1 vs 2; P < 0.01 for group 1 vs 3) and 53 (17) s, 46 (15) s and 35 (12) s for T4/T1 (P < 0.05 for group 1 vs 3), respectively. These data suggest that the tetanus-induced effect on subsequent TOF is more apparent and lasts longer at greater degrees than at lesser degrees of neuromuscular block.

Adult↗
PubMed1994

Middle cerebral arterial blood flow velocity increases during laparoscopic cholecystectomy.

The effects of intraperitoneal CO2 insufflation on middle cerebral arterial blood flow velocity were evaluated in 10 patients undergoing laparoscopic cholecystectomy under general anesthesia with nitrous oxide, oxygen, and isoflurane. Blood flow velocity was measured using transcranial Doppler ultrasonography. During CO2 insufflation, Paco2 and the end-tidal CO2 concentration (PETCO2) increased significantly compared with the preinsufflation baseline value (P < 0.01) while ventilation was kept constant. Cerebral blood flow velocity also increased significantly in comparison with the baseline value (P < 0.01). These values still exceeded baseline values 10 min after deflation of the peritoneal cavity. A significant positive correlation was observed between blood flow velocity and Paco2 (P < 0.001). Our results suggest that intraperitoneal CO2 insufflation during laparoscopic cholecystectomy increases cerebral blood flow and that this is probably due to an increased Paco2.

Adult↗
PubMed1994

[Effects of pressure support ventilation (PSV) or PSV+PEEP on the respiratory function during general anesthesia under spontaneous ventilation].

This study was performed to examine the hypothesis that PSV with PEEP compared to spontaneous breathing with a circle anesthesia system may have beneficial effects on gas exchange and work of breathing during inhalational anesthesia. Nine patients (age; 58 +/- 20 yr) scheduled to receive general anesthesia for orthopedic (n = 3) or ENT (n = 6) surgery were randomly assigned in a triple cross-over manner to breathe with a standard anesthesia circle system, 5 cmH2O PSV, and 5 cm H2O PSV above 5 cmH2O PEEP. General anesthesia was induced with thiamylal (5 mg.kg-1) and succinylcholine (1 mg.kg-1), followed by tracheal intubation. General inhalation anesthesia was maintained with 1% isoflurane and nitrous oxide in 40% oxygen. Patients were permitted to breathe spontaneously. A BiPAP-S Ventilatory Support System was connected to a standard anesthesia machine instead of a reservoir bag to deliver PSV or PSV with PEEP. Respiratory parameters were measured with a C-P 100 Pulmonary Monitor. After breathing for 20 minutes with the assigned mode, measurements and blood gas sampling were performed. Statistical analysis was performed with ANOVA. There were no statistical differences in PaO2 within the three groups (table). PaCO2 was lower during PSV+PEEP, but the difference was not significant. This level of PSV or PSV with PEEP may have little beneficial effects on gas exchange in our study condition. The mean WOBp was smaller in the PSV with PEEP group but the difference was not statistically significant.

Adult↗
PubMed1993

Contractility of fatigued diaphragm is improved by dobutamine.

The effects of dobutamine (DOB) on diaphragmatic fatigue were examined in 20 anaesthetized, mechanically ventilated dogs. Animals were divided into two groups: the DOB group (n = 10) and the control group (n = 10). Diaphragmatic fatigue was induced by intermittent supramaximal electric stimulation applied to bilateral phrenic nerves at a frequency of 20 Hz for 30 min. Diaphragmatic contractility was assessed with transdiaphragmatic pressure (Pdi). After diaphragmatic fatigue, Pdi decreased at low-frequency (20 Hz) stimulation (P < 0.05), whereas the decrease was minimal at high-frequency (100 Hz) stimulation. In the DOB group, after producing fatigue, the continuous administration of 10 micrograms.kg-1.min-1 dobutamine iv for 30 min produced an increased Pdi at both frequencies of stimulation (P < 0.05). The Pdi returned to pre-fatigue values after cessation of dobutamine administration. In the control group, the speed of recovery from fatigue was much slower at low-frequency stimulation. The integrated diaphragmatic electric activity (Edi) in the two groups did not change throughout the experiment at any frequency of stimulation. We conclude that dobutamine improves contractility in fatigued diaphragm.

Animals↗
PubMed1993

Studies on radiopaque composites containing ZrO2-SiO2 fillers prepared by the sol-gel process.

Radiopacity can facilitate diagnostic observations adjacent to dental composites. To produce radiopaque SiO2-based fillers, ZrO2-SiO2 powders containing up to 45wt% ZrO2 were manufactured by the sol-gel process. The radiopacity of experimental composites containing Bis-GMA+TEGDMA+CQ+DMAEMA monomer mixture (25 wt%) and ZrO2-SiO2 fillers (75 wt%) was evaluated and compared to that of human enamel and two commercial composites with different radiopacity. It became evident that the radiopacity of the experimental composites increased linearly with zirconium content and could match that of the control materials, while the composite containing 15wt% ZrO2-85wt% SiO2 filler possessed radiopacity analogous to that of human enamel. It was demonstrated here that the radiopacity of the composites could be precisely controlled by adjusting the ZrO2 content in ZrO2-SiO2 fillers. These radiopacity-adjustable composites have the potential to be very useful filling materials by enabling dentists to accurately distinguish secondary caries adjacent to the composite restorations.

Analysis of Variance↗
PubMed1993

Recoveries of post-tetanic twitch and train-of-four responses after administration of vecuronium with different inhalation anaesthetics and neuroleptanaesthesia.

We have studied recovery of post-tetanic twitch (PTT) and train-of-four (TOF) responses after administration of vecuronium in 100 patients under different inhalation anaesthetics and neuroleptanaesthesia. Patients were allocated randomly to five groups of 20 patients each to receive: neuroleptanaesthesia (droperidol and fentanyl), halothane, isoflurane, enflurane or sevoflurane (1 MAC in nitrous oxide and oxygen). The times from initial administration of vecuronium 0.2 mg kg-1 to the first appearances of T1, T2, T3 and T4 differed significantly between groups. However, the intervals to the first appearance of PTT1, PTT10 and PTT20 did not differ significantly between groups.

Adult↗
PubMed1993

Relationship between post-tetanic twitch and single twitch response after administration of vecuronium.

We have studied the relationship between post-tetanic twitch (PTT) and single twitch response after administration of vecuronium 0.2 mg kg-1 in 100 patients during neuroleptanaesthesia (NLA) (droperidol and fentanyl) and during anaesthesia with halothane, isoflurane, enflurane or sevoflurane (1 MAC in nitrous oxide and oxygen). Intervals from PTT1 to single twitch, and post-tetanic-count (PTC) (number of PTT responses) at the onset of single twitch were determined electromyographically. These intervals in the isoflurane, enflurane and sevoflurane groups differed from those in NLA and halothane groups. PTC in the isoflurane, enflurane and sevoflurane groups differed from those in the NLA group, and PTC in the sevoflurane group significantly from those in the NLA and halothane groups. These results are consistent with the view that PTT reflects prejunctional block, whilst the single twitch response is indicative of postjunctional block.

Adult↗