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Biomedical subjects

K Nitahara

Publications and source records attributed to K Nitahara.

At least 19 recordsLinked to original sources
PubMed2006

Risk factors for nausea and vomiting following vitrectomy in adults.

BACKGROUND AND OBJECTIVE: Postoperative nausea and vomiting (PONV) after ophthalmic surgery under general anaesthesia remains a complex and perturbing complication associated with several factors. Little information is available regarding the risk factors for nausea and vomiting after vitrectomy in adults. In this study, we evaluated the potential risk factors for PONV after vitrectomy in adult patients. METHODS: Univariate and multivariate analyses of clinical factors associated with PONV were undertaken in a retrospective case-control series of 247 adult patients undergoing vitrectomy under general anaesthesia. We examined PONV for the first 48 h. Factors examined were age, body mass index (BMI), smoking status, H2-blocker as premedication, type of general anaesthesia (sevoflurane and fentanyl or total intravenous (i.v.) anaesthesia with propofol and fentanyl), duration of surgery, and intraoperative fentanyl dose. RESULTS: Fifty-nine patients (24%) reported one or more episodes of PONV during the study period. Female gender (P < 0.01), lower BMI (P < 0.01) and general anaesthesia with inhalational anaesthetics (P < 0.01) were significantly related to nausea during the first 2 h postoperatively. Female gender (P < 0.01) was significantly related to nausea and vomiting throughout the study period. Other factors, including smoking status, did not alter the risk for nausea and/or vomiting. CONCLUSIONS: We conclude that female gender, lower BMI and inhalation anaesthesia are the main risk factors for PONV after vitrectomy in adults. Smoking status did not reduce the incidence of PONV in our patients.

Adolescent↗
PubMed2006

Optimal depth of insertion of left-sided double-lumen endobronchial tubes cannot be predicted from body height in below average-sized adult patients.

BACKGROUND AND OBJECTIVE: The optimal depth of insertion of left-sided double-lumen endobronchial tubes is strongly correlated with body height in average-sized adults. However, this relationship has not been studied in below average-sized adult patients. We investigated whether or not there is a clinically useful relationship in below average-sized adult patients. METHODS: One hundred and ninety six consecutive adult patients undergoing thoracic surgery under one-lung anaesthesia (body height < or = 155 cm) were included in this study. Left-sided double-lumen tubes were inserted under the guidance of a fibre-optic bronchoscope. Optimal depth was defined as the proximal surface of the bronchial cuff positioned just below the carina. RESULTS: There was a statistically significant positive correlation between body height and the optimal depth of insertion (r = 0.61, P < 0.0001); however, the correlation coefficient was low. The actual optimal depth of insertion of one patient was even 4.5 cm shorter than that obtained from the equation. CONCLUSION: Although there was a statistically significant correlation between body height and the optimal depth of insertion of left sided double lumen tubes in adult patients of short stature (< or = 155 cm), clinical application of the equation is not warranted and these tubes should be inserted under direct vision with a fibre-optic bronchoscope.

Aged↗
PubMed2004

Use of epidural anaesthesia for surgery in a patient with Kennedy's disease.

Use of neuraxial block in a patient with motor neuron disease is controversial. We describe the anaesthetic management by epidural anaesthesia of a patient with Kennedy's disease, a rare lower motor neuron disease characterized by progressive weakness and wasting of limbs and bulbar muscles. The perioperative course was uneventful, and there was no exacerbation of neurologic signs or symptoms. We suggest that a patient with Kennedy's disease may be successfully managed by epidural anaesthesia for surgical internal urethrotomy.

Anesthesia, Epidural↗
PubMed2003

Effect of continuous low-dose intravenous diltiazem on epidural fentanyl analgesia after lower abdominal surgery.

BACKGROUND: The postoperative opioid-sparing effects of systemic L-type calcium channel blockers are controversial. We investigated whether the postoperative analgesic effect of epidural fentanyl was enhanced by i.v. infusion of diltiazem at a rate that would minimize any cardiovascular depressant effect. METHODS: After elective lower abdominal gynaecological surgery, 30 patients were randomized to receive continuous i.v. diltiazem 1 micro g kg(-1) min(-1) (diltiazem group) or the same volume of saline (control group) for 24 h. Cumulative postoperative epidural fentanyl consumption, visual analogue scale (VAS) scores and verbal rating scores (VRS) at rest and during mobilization, sedation scores, incidence of side-effects and overall patient satisfaction were assessed. RESULTS: There was no significant difference in cumulative epidural fentanyl consumption between the groups at any period. Although there were no statistically significant differences in VAS scores, VRS, sedation scores, incidence of side-effects and overall patient satisfaction, there was a trend to an increased incidence of nausea in the diltiazem group. CONCLUSIONS: Continuous i.v. infusion of diltiazem did not reduce epidural fentanyl consumption when administered at dosages having minimal haemodynamic depressant effects.

Analgesia, Epidural↗
PubMed2002

Oral clonidine premedication reduces the EC50 of propofol concentration for laryngeal mask airway insertion in male patients.

BACKGROUND: Oral clonidine, an alpha2-adrenergic receptor agonist, reduces the dose of propofol required for laryngeal mask airway (LMA) insertion. Target-controlled infusion (TCI) is becoming increasingly popular for propofol infusion. There is no information, however, on the propofol blood concentrations required for LMA insertion and the effect of oral clonidine premedication on these values. METHODS: Propofol at target effect-site concentrations from 4.0 to 12.0 microg/ml were randomly administered using TCI in three groups of healthy male patients (n=35 each) who were undergoing elective orthopedic surgery: control, 2.5 microg/kg clonidine, and 5.0 microg/kg clonidine groups. Nothing was administered to the control group. Clonidine(2.5 microg/kg or 5.0 microg/kg) was administered orally 90 min before arrival at the operating room in the clonidine groups. After equilibration between the blood- and effect-site for 15 min, insertion of the LMA was attempted. The EC50 for LMA insertion (measured propofol serum concentration in equilibrium with the effect-site at which 50% of patients do not respond to the insertion of the LMA) was determined by logistical regression. RESULTS: EC50+/-standard error values in the control, 2.5 microg/kg clonidine, and 5.0 microg/kg clonidine groups were 8.72+/-0.55, 7.76+/-0.60, and 5.84+/-0.58 microg/ml, respectively. The EC50 in the 5.0 microg/kg clonidine group was significantly lower than that in the control group (P < 0.01). CONCLUSIONS: The propofol concentration required for LMA insertion in healthy male patients is reduced by premedication with 5.0 microg/kg oral clonidine.

Adrenergic alpha-Agonists↗
PubMed2001

[Anesthetic management of a patient with tetanus using epidural anesthesia].

A 75-year-old woman with breast cancer complicated with tetanus was scheduled for mastectomy. Since severe bradycardia (17 beats.min-1) was detected by preoperative Holter monitoring, a temporary pacing catheter was inserted. She underwent mastectomy under general anesthesia using propofol combined with thoracic epidural anesthesia. She also received postoperative thoracic epidural block. Her perioperative heart rate was 80-105 beats.min-1 and the rhythm was sinus. There was no marked perioperative cardiovascular derangement.

Aged↗
PubMed2000

Stimulation-dependent release, breakdown, and action of endogenous ATP in mouse hemidiaphragm preparation: the possible role of ATP in neuromuscular transmission.

In this study the in vitro mouse phrenic nerve- hemidiaphragm preparation was utilized to study the release and extracellular catabolism of endogenous ATP and its action on the postsynaptic site, i.e. on the contraction force evoked by nerve stimulation. ATP, measured by the luciferin-luciferase assay, was released stimulation-dependently from the mouse hemidiaphragm in response to electrical field stimulation at 10 Hz. Blockade of the Na(+) channel activity by tetrodotoxin inhibited the majority of the release of ATP in response to stimulation, showing that it is related to neuronal activity. The nicotinic receptor antagonists d-tubocurarine, and alpha-bungarotoxin and cooling the bath temperature to 7 degrees C also reduced stimulation-induced ATP outflow, suggesting that nicotinic receptors are responsible for the part of the release of ATP that is released from postsynaptic sites in a carrier-mediated manner. Exogenous ATP (20-500 microM) added to the bath was degraded to ADP and AMP by the action of ectoATPase and ectoATPdiphosphohydrolase; the K(m) and v(max) values of these enzymes were 185.8 microM and 55.16 nmol/min.g respectively. However, the total amount of nucleotides ([ATP+ADP+AMP]) was increased after the addition of ATP, indicating that ATP itself promoted further adenine nucleotide release. Twitch contractions of the rat hemidiaphragm preparation evoked by low frequency electrical stimulation was blocked concentration-dependently by the non-depolarizing muscle relaxants d-tubocurarine and pancuronium. Suramin (100 microM-1 mM) reversed neuromuscular blockade by d-tubocurarine and pancuronium; i.e., it shifted their concentration-response curves to the right Taken together our data, that endogenous ATP is released by stimulation and subsequently catabolized in the hemidiaphragm preparation and that suramin inhibits ecto-ATPase activity could be interpreted as meaning that suramin prolongs the action of endogenous ATP to elicit twitch contraction, which points to a new, undefined role of ATP in neuromuscular transmission. The source of ATP is partly postsynaptic, released from the muscle in response to activation of nicotinic ACh receptors expressed on the muscle.

Adenosine Triphosphatases↗
PubMed2000

Adenosine potentiation of neuromuscular blocking agents in guinea-pigs.

We have investigated the effects of adenosine i.v. on neuromuscular block induced by rocuronium, vecuronium and pipecuronium in an in vivo guinea-pig sciatic nerve-tibialis anterior preparation. The ED50 of each neuromuscular blocker was determined from cumulative log dose-response regression lines (n = 14). In separate experiments, adenosine 0.1 mg kg-1 min-1 or the same volume of 0.9% NaCl was given i.v. via a constant infusion and the ED50 of each neuromuscular blocking agent was then administered (n = 24). Adenosine 0.1 mg kg-1 min-1 increased significantly maximal block induced by the ED50 of these neuromuscular blockers (55-72%, 49-73% and 60-96%, respectively, for rocuronium, vecuronium and pipecuronium; P < 0.05). Time to maximal block after rocuronium was significantly prolonged by adenosine (1.4-2.1 min; P < 0.05) and time to maximal block after vecuronium and pipecuronium was unchanged by adenosine. Time to maximal recovery of twitch tension after administration of the ED50 of all neuromuscular blocking agents was prolonged significantly by adenosine (4.5-10.7 min, 8.2-15.8 min and 47.0-128.7 min, respectively, for rocuronium, vecuronium and pipecuronium; P < 0.05). We conclude that continuous infusion of adenosine 0.1 mg kg-1 min-1 potentiated the effects of neuromuscular blocking agents in this in vivo guinea-pig preparation.

Adenosine↗
PubMed2000

Modification of the Koyanagi technique for the single stage repair of proximal hypospadias.

PURPOSE: We describe a modification of the Koyanagi technique for hypospadias. Use of opposing parameatal-based skin flaps that extend distally to incorporate the inner layer of the prepuce was modified to preserve blood supply to the flaps in an attempt to reduce complications and improve results. MATERIALS AND METHODS: During the last 7 years 20 boys underwent treatment of proximal hypospadias using the modified hypospadias repair. RESULTS: Cosmetic and functional, long-term (mean 34 months) results were excellent. Complications consisted of 4 urethrocutaneous fistulas (20%). There were no instances of meatal stenosis, diverticulum or urethral stricture. CONCLUSIONS: The modified technique permits 1-stage repair of proximal hypospadias with a low complication rate.

Child, Preschool↗
PubMed1999

Response to vecuronium in a patient with facioscapulohumeral muscular dystrophy.

Increased sensitivity to vecuronium has been noted in patients with Duchenne muscular dystrophy. We report the response to vecuronium in a patient with facioscapulohumeral muscular dystrophy (FSHD), an autosomal dominant disorder with an incidence of 10-20 cases per million. In this patient, sensitivity to an initial dose of vecuronium (0.02 + 0.08 mg kg-1) was normal, but recovery was faster and the effect of incremental doses of vecuronium (0.02 mg kg-1) was less than expected. Onset time and 25% recovery of T1/T0 after the intubating dose of vecuronium were 240 s and 22 min, respectively. Recovery index (spontaneous recovery of T1/T0 from 25% to 75%) was 9 min.

Adult↗
PubMed1998

Changes in tissue oxygen tension caused by contrast media injected into the femoral artery of the dog.

PURPOSE: To document changes in tissue oxygen tension as measured directly in an area perfused with contrast medium. MATERIAL AND METHODS: Changes in tissue oxygen tension in response to the injection of ionic and non-ionic contrast media into the femoral arteries were measured in the femoral adductor (proximal) and gastrocnemius (distal) muscles of 8 dogs. Amidotrizoic-acid and iopamidol were injected in two different iodine concentrations (370 mg I/ml and 185 mg I/ml respectively) and tissue oxygen tension in the proximal and distal muscles was monitored continuously using polarographic needle electrodes. RESULTS AND CONCLUSION: A transient decrease and subsequent increase of muscle tissue oxygen tension were observed after the injection. The extent of these changes depended on the concentration and osmolality of the medium. To minimize changes in peripheral tissue oxygen tension, contrast media with low osmolality and low concentration are recommended for femoral angiography.

Angiography↗
PubMed1995

A1-receptor-mediated effect of adenosine on the release of acetylcholine from the myenteric plexus: role and localization of ecto-ATPase and 5'-nucleotidase.

No attempt has been made so far to classify the subtypes of presynaptic inhibitory adenosine receptors located in the myenteric plexus and to localize ecto-ATPase and 5'-nucleotidase in the intestine. The release of [3H]acetylcholine and smooth muscle responses to acetylcholine were measured and the effect of selective adenosine receptor ligands was studied using field-stimulated isolated longitudinal muscle strips of guinea-pig ileum. Release of ATP and its hydrolysis rate were also measured using the luciferin-luciferase technique. A histochemical method combined with electron microscopy was used for localization of ecto-ATPase and 5'-nucleotidase, enzymes responsible for destruction of extracellular ATP, ADP and AMP. Subtype-selective A1-receptor agonists and antagonists inhibited and enhanced, respectively, the release of acetylcholine associated with neuronal activity. A significant amount of ATP was released in response to electrical stimulation and administration of carbamylcholine. The release of ATP was inhibited by atropine and 4-diphenylacetoxy-N-methylpiperidine methiodide, an M3-receptor antagonist. Hydrolysis of ATP was rapid and resulted in an accumulation of extracellular adenosine involved in presynaptic A1-receptor-mediated inhibition of acetylcholine release. While the inhibitory effect of adenosine and ATP was significantly potentiated by dipyridamol, an adenosine uptake blocker, that of 2-ms ATP was not. The effect of ATP was not competitively antagonized by 8-cyclopentyl-1,3-dipropylxanthine, a selective A1-receptor antagonist. In conclusion, axon terminals of cholinergic interneurons are equipped with inhibitory A1- and P2 gamma-receptors. Therefore, both adenosine and ATP control the release of acetylcholine through these receptors. ATP is mainly released from the smooth muscle in response to stimulation of M3-muscarinic receptors by endogenous acetylcholine (cascade transmission [Vizi E. S. et al. (1992) Neuroscience 50, 455-465]) and is rapidly hydrolysed by ecto-ATPase localized on the surface of the smooth muscle and axon terminals producing ADP and AMP, and by 5'-nucleotidase present only on the surface of smooth muscle cells producing adenosine.

5'-Nucleotidase↗
PubMed1995

Neurochemical evidence that [Ca2+]o antagonizes the effect of neomycin on acetylcholine release from mouse hemidiaphragm preparation: an attempt to assess the margin to safety.

Although the neuromuscular junction is the most thoroughly studied synapse of any type and has become the model of our understanding of synaptic transmission, some questions remain unanswered; e.g. there has been no direct assessment of the size of margin of safety. In this study the [Ca2+]o-dependent, quantally released acetylcholine measured by a neurochemical method, and the contraction of the mouse hemidiaphragm in response to phrenic nerve stimulation were recorded, and the effect of neomycin was studied. It was found that a much higher concentration of neomycin was needed to depress contractions, than to reduce acetylcholine release to the same extent, and that there was an inverse correlation between [Ca2+]o and the inhibitory effect of neomycin on acetylcholine release. Ninety percent of the release of acetylcholine had to be reduced by neomycin before any reduction in muscle responses could be seen. This indicates that the margin of safety is about 10. In conclusion, at the neuromuscular junction any reduction in ACh release, whatever the mechanism, first produces a reduction in the margin of safety. The nondepolarizing neuromuscular blocking agents block primarily the nicotinic receptors located on the postjunctional site. Many receptors have to be blocked before a reduction of muscle response is observed. This is probably the reason why unexpected clinical problems (e.g. recurarization) have been described when a patients has been treated with antibiotics, even though the dose of muscle relaxant injected was relatively low.

Acetylcholine↗
PubMedDate not supplied

Blood flow velocity changes in carotid and vertebral arteries with stellate ganglion block: measurement by magnetic resonance imaging using a direct bolus tracking method.

BACKGROUND AND OBJECTIVES: Stellate ganglion block (SGB) leads to vasodilation of the head and neck, as a result of a regional sympathetic blockade. However, in such cases, controversy remains concerning changes in cerebral and extracerebral blood flow in the head. We estimated the effect of SGB on blood flow in the head by measuring the blood flow velocity in cervical vessels, using magnetic resonance imaging and the direct bolus tracking method. This noninvasive method is free from potential artifacts of bones and other connective tissues. METHODS: Seven adult patients with acute or chronic pain in the head or neck underwent SGBs, using an anterior paratracheal approach with 6-8 mL of 1% mepivacaine (3 right and 4 left SGBs). Blood flow velocity in common carotid and vertebral arteries (CCA and VA) was measured simultaneously before and after SGB, using the direct bolus tracking method. RESULTS: On the side of SGB, blood flow velocity in CCA significantly increased (P < .002), whereas velocity in VA was unchanged after SGB. On the side contralateral to the SGB, significant changes in blood flow velocity in CCA and VA were never observed. CONCLUSIONS: Blood from the VA flows primarily to cerebral vessels, whereas that from CCA goes to both cerebral and extracerebral vessels. Given the presumed differences in blood flow distribution through the VA and CCA, we assume that the observed CCA blood flow increases, ipsilateral to the SGB, primarily as a result of vasodilation of extracerebral vessels and independent of changes in brain blood flow.

Acute Disease↗