Hideya Ohmori

Intrathecal buprenorphine in the treatment of phantom limb pain.

I? hantom limb pain is a chronic pain perceived in an absent part of the body. It can totally consume a patient’s life. Suggested treatments for this complaint are many, but none have proved to have lasting efficacy. We have treated two patients suffering from phantom limb pain. Intrathecal buprenorphine provided not only immediate and long-lasting pain relief, but also increased the temperature of the lower part of the body. These cases are described and possible mechanisms for the analgesic and hyperthermic actions of intrathecal buprenorphine are discussed.

The anticonvulsant action of propofol on epileptiform activity in rat hippocampal slices.

We used extracellular electrophysiological recordings from the CA1 region in rat hippocampal slices to investigate the effects of propofol on the field excitatory postsynaptic potential (fEPSP), population spike, and epileptiform activity induced by a Mg2+-free condition. Propofol depressed the population spike, fEPSP, and epileptiform activity. Both aminophylline, a nonselective adenosine receptor antagonist, and 8-cyclopentyl-1,3-dipropylxanthine, an A1 receptor antagonist, significantly reduced the effect of propofol on fEPSP amplitude. However, 3,7-dimethyl-1-propagylxanthine, an A2 receptor antagonist, did not alter the effect of propofol on fEPSP amplitude. Picrotoxin, a specific chloride channel blocker, partly reduced the effect of propofol on epileptiform activity, but bicuculline, a competitive &ggr;-aminobutyric acidA receptor antagonist, failed to antagonize it. Aminophylline significantly reduced the action of propofol on the epileptiform activity. The anticonvulsant action of propofol was partly reduced by 8-cyclopentyl-1,3-dipropylxanthine, whereas 3,7-dimethyl-1-propagylxanthine failed to affect it. Adenosine depressed the amplitude of fEPSPs in a dose-dependent manner, and propofol enhanced this inhibition. The results demonstrated that, in rat hippocampal slices, propofol inhibits epileptiform activity. In addition, adenosine neuromodulation through the A1 receptor may contribute to the anticonvulsant action of propofol.

Differential effects of propofol, thiamylal and ketamine on the cricothyroid and posterior cricoarytenoid muscles of the canine larynx

PurposeTo measure the electromyographic (EMC) responses of the phasic discharge in the cricothyroid (CT; a tensor muscle of the vocal folds) and the posterior cricoarytenoid (PCA; sole abductor muscle of the vocal folds) following intravenous infusion of propofol 1.0 mg · kg−1 · min−1, thiamylal 1.0 mg · kg−1 · min−1, or ketamine 0.5 mg · kg−1 · min−1 for five minutes.DesignProspective, nonrandomized, controlled animal study. Setting: University research laboratory. Subjects: Fifteen mongrel dogs, including three groups of five animals in each group.InterventionsUnder 0.2–0.3% halothane and oxygen anesthesia with spontaneous ventilation, phasic EMG activities of the CT and PCA muscles were recorded in an identical manner after the administration of each drug.Measurements and main resultsPropofol infusion produced almost equal suppression of EMG activity of the CT and the PCA with lime and three minutes after the start of infusion of propofol there was a significant depression of the phasic activities in the both muscles; EMG activity of the CT and the PCA was 33.8 ± 21.2 and 36.6 ± 22.9% (% of control, mean ± SD) respectively P < 0.05). Thiamylal selectively reduced rhythmic discharges in the CT muscle during spontaneous breathing and significant depression of discharge in the CT muscle was observed three minutes after the drug (47.3 ± 24.9%, P < 0.05). In contrast, both phasic EMG activities of the CT and the PCA were rhythmically active and the differential sensitivity between the CT and the PCA muscles was not observed after ketamine, even after ten minutes of administration.ConclusionsThis study confirms a difference in sensitivity between the CT and the PCA muscles, demonstrating that the intrinsic laryngeal muscles do not behave similarly after the administration of conventional intravenous anaesthetic agents.RésuméObjectifMesurer la réponse électromyographique (EMG) de la décharge phasique du muscle cricothyrodien (CT: un des muscles tenseurs des cordes vocales) et la cricoaryténodien postérieur (CAP: le seul muscle abducteur des cordes vocales) après une perfusion intraveineuse de propofol 1,0 mg · kg−1· min−1, de thyamilal 1,0 mg · kg−1 · min−1 ou de kétamine 0,5 mg · kg−1 · min−1 pendant cinq minutes.Organisation de l’étudeProspective, non aléatoire, contrôlée, sur des animaux.MilieuLaboratoire de recherche universitaire.SujetsQuinze chiens de race commune divisés en trois groupes de cinq.InterventionsSous anesthésie en ventilation spontanée à l’halothane 0,2–0,3% en oxygène, l’activité phasique EMG des muscles CT et CAP est enregistrée de manière identique après l’administration de chaque agent.Mesures et principaux résultatsLa perfusion de propofol produit une suppression presque identique de l’activité EMG du CT et CAP avec le temps. Trois minutes après le début de la perfusion de propofol, on constate une dépression importante de l’activité phasique des deux muscles; l’activité phasique du CT et du CAP est respectivement de 33,8 ± 21,2 et 36,6 ± 22,9 (% du contrôle, moyenne ± ET, P < 0,05). Par contre, l’activité EMG phasique du CT et du CAP était en harmonie et une différence de sensibilité entre les muscles CT et CAP n’a pas été observée avec la kétamine, même après dix minutes d’administration.ConclusionCette étude confirme la différence de sensibilité qui existe entre les muscles CT et CAP et démontre que les muscles intrinseques du larynx ne se comportent pas de la même façon après l’administration des anesthésiques intraveineux usuels.

Influence of continuous positive airway pressure on EMG activities of the cricothyroid and posterior cricoarytenoid muscles of the canine larynx.

ObjectivesWe investigated the effect of different levels of continuous positive airway pressure (CPAP) on the cricothyroid (CT; a tensor muscle of the vocal folds) and posterior cricoarytenoid (PCA; sole abductor muscle of the vocal folds) muscles in dogs.DesignProspective, controlled animal study.SubjectsNine mongrel dogs of both sexes.SettingUniversity research laboratory.InterventionsAfter insertion of a cuffed tracheotomy tube low in the neck the compound EMG responses of the CT and PCA muscles during spontaneous respiration were measured simultaneously under different levels (2, 4, 6, and 8 cmH2O) of positive end-expiratory pressure (PEEP).Measurements and resultsThe CT showed a progressive increase in phasic expiratory EMG activity with the application of graded levels of PEEP. Application of PEEP over 4 cmH2O produced significant increases in the phasic CT activity (P<0.05). In contrast to the CT, the PCA failed to increase phasic inspiratory EMG activity statistically until a 8 cmH2O of PEEP was applied (P<0.05). The phasic experatory CT and inspiratory PCA activities were 297.9±77.6 and 124.5±22.9, respectively, at the application of 6 cmH2O of PEEP (percentage of control, mean±SD).ConclusionThis study confirms the difference in sensitivity between adductor and abductor laryngeal muscles, demonstrating that the intrinsic laryngeal muscles do not all behave similarly after the application of CPAP.