Masayasu Nakayama

Differential Effects of Propofol and Sevoflurane on Heart Rate Variability

Background Propofol is reported to reduce both sympathetic and parasympathetic tone; however, it is not clear whether the changes in heart rate variability are associated with depth of anesthesia. The purposes of the present study were (1) to evaluate the changes in heart rate variability at different depths of hypnosis and (2) to compare the effects of propofol on heart rate variability with that of sevoflurane. Methods Thirty patients were randomly allocated into the propofol or sevoflurane for induction of anesthesia. The depth of hypnosis was monitored by the Bispectral Index (BIS). Spectral analysis of heart rate variability using a maximum-entropy method resulted in a characteristic power spectrum with two main regions, a high frequency (HF) and a low frequency (LF). Hemodynamics, entropy, LF, HF, and LF/HF were monitored when the patients were awake and after induction of anesthesia. Results Both propofol and sevoflurane decreased blood pressure in a BIS-dependent manner, whereas heart rate showed no significant changes during the study period. In the propofol group, entropy and HF decreased with a reduction in the BIS value. Although LF decreased after induction of anesthesia, propofol caused no further decrease in LF in spite of a reduction in the BIS value. In the sevoflurane group, LF decreased with a reduction in the BIS value. Entropy and HF decreased after induction of anesthesia (BIS at 80); however, no further decreases were observed in spite of a reduction in the BIS value. Conclusions Induction of anesthesia with propofol decreased blood pressure, entropy, and HF in a BIS-dependent manner, indicating that propofol reduces cardiac parasympathetic tone depending on the depth of hypnosis. Conversely, sevoflurane did not show the BIS-dependent decreases in heart rate, blood pressure, HF, and entropy, indicating that sevoflurane has little or no effect on cardiac parasympathetic tone.

Ketamine preserves and propofol potentiates Hypoxic pulmonary vasoconstriction compared with the conscious state in chronically instrumented dogs

BACKGROUND The authors tested the hypothesis that ketamine and propofol anesthesia would alter the magnitude of hypoxic pulmonary vasoconstriction compared with the conscious state. In addition, they assessed the extent to which cyclooxygenase pathway inhibition and adenosine triphosphate-sensitive potassium channel inhibition modulate hypoxic pulmonary vasoconstriction in the conscious state, and whether these pathways are altered during propofol anesthesia. METHODS Twenty conditioned, male mongrel dogs were chronically instrumented to measure the left pulmonary vascular pressure-flow relationship. Pressure-flow plots were measured during normoxia and hypoxia (systemic arterial PO2 reduced to about 60 and about 50 mm Hg) on separate days in the conscious state, during ketamine anesthesia, and during propofol anesthesia. The effects of indomethacin and glibenclamide on the magnitude of hypoxic pulmonary vasoconstriction were also assessed in the conscious and propofol-anesthetized states. RESULTS Neither ketamine nor propofol had an effect on the baseline pressure-flow relationship during normoxia compared with the conscious state. Hypoxia resulted in stimulus-dependent pulmonary vasoconstriction (P<0.01) in the conscious state. Compared with the conscious state, the magnitude of hypoxic pulmonary vasoconstriction was preserved during ketamine but was potentiated (P<0.01) during propofol anesthesia. Indomethacin enhanced (P<0.01) hypoxic pulmonary vasoconstriction in both the conscious and propofol-anesthetized states. In contrast, glibenclamide only enhanced (P<0.01) hypoxic pulmonary vasoconstriction in the conscious state and had no effect during propofol anesthesia. CONCLUSION Hypoxic pulmonary vasoconstriction is preserved during ketamine anesthesia but is potentiated during propofol anesthesia. The potentiated response during propofol anesthesia appears to be caused by inhibition of adenosine triphosphate-sensitive potassium channel-mediated pulmonary vasodilation.

Forehead is as sensitive as finger pulse oximetry during general anesthesia

PurposeTo compare the performance of a forehead probe to a conventional finger pulse oximetry probe in anesthetized patients.MethodsEighteen patients participated in the study. Each probe was connected to a Nellcor N-550 pulse oximeter. Anesthesia was induced and maintained with propofol. After intubation, the patients received air to achieve a steady-state of peripheral arterial oxygen saturation (SpO2). Ventilation was interrupted to induce a hypoxic state. As soon as one of the two SpO2’s decreased to 90%, the patients’ lungs were ventilated with 100% oxygen. To evaluate the performance of the two pulse oximeters, time to the lowest (TL), time of recovery (TR) and lag times to beginning of SpO2 decrease (Lag) were measured.ResultsThere were no significant differences in TL and TR between forehead and finger pulse oximetry under normal perfusion conditions during general anesthesia. When the axillary artery was compressed to mimic reduced peripheral perfusion, SpO2 in the forehead decreased sooner than in the finger during hypoxia. The forehead and finger TLs were similar, however, TR was significantly longer in the finger.ConclusionThe forehead SpO2 sensor can be used as an alternative to the conventional finger sensor during general anesthesia.RésuméObjectifComparer la performance d’un capteur frontal et d’un capteur traditionnel au doigt chez des patients anesthésiés.MéthodeDix-huit patients ont participé à l’étude. Chaque capteur a été relié à un sphygmo-oxymètre Nellcor N550. L’anesthésie a été induite et maintenue avec du propofol. Après l’intubation, les patients ont reçu de l’air pour l’obtention d’un état d’équilibre de la saturation en oxygène du sang artériel périphérique (SpO2). La ventilation a été interrompue pour induire un état hypoxique. Aussitôt qu’une ou l’autre mesure de SpO2 baissait à 90 %, les patients étaient ventilés avec de l’oxygène à 100 %. La performance des deux appareils a été mesurée par le temps nécessaire pour obtenir la plus basse valeur de SpO2 (TB), le temps nécessaire à la récupération (TR) et les intervalles précédant les baisses de SpO2 (Int).RésultatsIl n’y a pas eu de différences significatives de TF et TR entre les résultats notés au front et au doigt dans des conditions normales de perfusion pendant l’anesthésie générale. Quand l’artère axillaire était compressée pour imiter une perfusion périphérique réduite, la SpO2 diminuait plus vite au front qu’au doigt pendant l’hypoxie. Les TF au front et au doigt ont été similaires, mais le TR a été significativement plus long au doigt.ConclusionLe capteur frontal de SpO2 peut remplacer un capteur traditionnel fixé au doigt pendant l’anesthésie générale.

Analgesic effect of epidural neostigmine after abdominal hysterectomy.

STUDY OBJECTIVE To evaluate the effects of epidurally administered neostigmine on pain after abdominal hysterectomy. DESIGN Prospective, randomized, double-blind study. SETTING Teaching hospital. PATIENTS 45 ASA physical status I adult patients scheduled for abdominal hysterectomy. INTERVENTIONS All patients received identical general and epidural anesthesia. At the end of the surgery, they received epidural bupivacaine (10 mg) with either saline (control group, n = 15), 5 micro g/kg (5-micro g group, n = 15), or 10 micro g/kg neostigmine (10-micro g group, n = 15). Postoperatively, 50 mg diclofenac suppository was given for pain relief on patient demand. MEASUREMENTS AND MAIN RESULTS The time to first diclofenac administration and the number of times diclofenac was required during the first 24 postoperative hours were recorded. Pain was assessed using a 10-cm visual analog pain scale (VAS) at rest at the first diclofenac request, and at 15 and 24 hours after surgery. The time to first diclofenac administration was significantly longer (p < 0.05) in the 10-micro g group (223 +/- 15 min) than in the control (78 +/- 17 min) or 5-micro g groups (88 +/- 18 min). However, epidural neostigmine at both doses did not reduce the number of postoperative diclofenac administrations. There were no differences in VAS among the three groups. CONCLUSIONS Epidural neostigmine of 10 micro g/kg in bupivacaine provides a longer duration of analgesia than does bupivacaine alone or with 5 micro g/kg of neostigmine after abdominal hysterectomy.

Recovery characteristics and post-operative delirium after long-duration laparoscope-assisted surgery in elderly patients: propofol-based vs. sevoflurane-based anesthesia.

Background:  Post‐operative mental dysfunction may be an important problem in elderly patients. This study was designed to compare the effects of propofol and sevoflurane anesthesia on recovery characteristics and the incidence of post‐operative delirium (POD) in long‐duration laparoscopic surgery for elderly patients.

Comparison of haemodynamic changes induced by sevoflurane and halothane in paediatric patients

The purpose of this study is to investigate the haemodynamic effects of 1 MAC and 2 MAC of sevoflurane in children in comparison with halothane. Thirty-eight children (aged from one to six years, average age; 3.6± 0.2 yr) were randomly assigned to four groups, depending on the dose and agent (1 and 2 MAC of sevoflurance: SI and S2; 1 and 2 MAC of halothane: H1 and H2, respectively). After collecting control data during 0.2 MAC of either anaesthetic, end-expired anaesthetics were kept at 1 MAC or 2 MAC for 15 min. Mean blood pressure (mBP) and stroke volume index (SV1), measured by impedance cardiometry, decreased in all groups without differences between groups. Heart rate (HR) increased in groups S1, S2 and H2 but not in group H1. The HR in S2 was higher than that in H2. The cardiac index (CI), a product of SVI and HR, tended to decrease but not significantly in all groups. These results suggested that the haemodynamic depressant effects of sevoflurane in children were similar to those of equipotent halothane concentration except for HR.RésuméCette étude vise à comparer, avec celles de I’halothane, les répercussions sur l’hémodynamique des enfants du sévoflurane à MAC 1 et 2. Trente-huit enfants (âgés de un à six ans, en moyenne 3,6± 0,2 ans) sont répartis au hasard en quatre groupes, selon la concentration et l’agent (S1 et S2: sévoflurane MAC 1 et 2; H1 et H2: halothane MAC 1 et 2 respectivement). Après le recueil des données de contrôle pendant une anesthésie à MAC 0,2, la concentration téléexpiratoire de l’anesthésique est maintenue à MAC I or 2 pour 15 min. La pression artérielle moyenne (PAM) et l’index systolique (IS), mesuré par la cardiomètrie par impédance, diminue dans tous les groupes et sans présenter de différences entre les groupes. La fréquence cardiaque (Fc) augmente dans les groupes S1, S2 et H2 mais pas dans le groupe H1. La Fc dans S2 est plus élevée que dans H2. L’index cardiaque, le produit de IS et de Fc, tend à diminuer mais non signiflcativement dans tous les groupes. Ces résultats suggèrent que les effets dépresseurs sur l’hémodynamique du sévoflurane chez les enfants sont identiques à ceux d’une concentration équivalente d’halothane.

Perioperative intravenous flurbiprofen reduces postoperative pain after abdominal hysterectomy

Purpose: To assess whether perioperative intravenous administration of flurbiprofen, a non-steroidal anti-inflammatory drug, reduced postoperative pain after abdominal hysterectomy.Methods: Forty-five patients undergoing abdominal hysterectomy were randomly assigned to one of three groups of equal size. A control group (CONT) received a placebo 30 min before and at the end of surgery. The other two groups, PRE and POST, received 1 mg·kg−1 flurbiprofeniv 30 min before and at the end of surgery, respectively. All patients received identical general and epidural anesthesia. Postoperatively, 50 mg diclofenacpr was given for pain relief on patient demand. One of the authors assessed pain using a 10 cm visual analog scale at rest and during coughing at the first request for diclofenac, and at 15, 24, 48, and 72 hr after surgery. The number of times diclofenac was required during the first 24 hr after surgery was also recorded.Results: The number of diclofenac requests in the PRE (1.8±0.4) and POST groups (2.0±0.4) were less than in the CONT group (3.0±0.4). The PRE group showed lower visual analog scale at rest at 15 and 24 hr and on coughing at 24, 48, and 72 hr after surgery than the CONT and POST groups.Conclusion: intravenous 1 mg·kg− flurbiprofen administered during anesthesia reduces postoperative rescue analgesic requirement after abdominal hysterectomy. Moreover, flurbiprofen is more effective when given before than after surgery.RésuméObjectif: Vérifier si l’administration intraveineuse périopératoire de flurbiprofène, un anti-inflammatoire non stéroïdien, réduit la douleur postopératoire d’une hystérectomie abdominale.Méthode: Quarante-cinq patientes devant subir une hystérectomie abdominale ont été réparties au hasard en trois groupes égaux. Un groupe témoin (TEM) a reçu un placebo, 30 min avant et à la fin de l’opération. Les deux autres groupes, PRE et POST, ont reçu 1 mg·kg−1 de flurbiprofèneiv 30 min avant et à la fin de l’intervention, respectivement. Toutes les patientes ont reçu une anesthésie générale et épidurale identique. Après l’intervention, 50 mg de diclofénacpr ont été administrés sur demande comme analgésie. Un des auteurs a évalué la douleur en utilisant une échelle visuelle analogique de 10 cm, au repos et pendant la toux à la première demande de diclofénac et, puis à 15, 24, 48 et 72 h après l’opération. On a aussi noté le nombre de demandes de diclofénac pendant les 24 premières heures postopératoires.Résultats: Les demandes de diclofénac dans les groupes PRE (1,8±0,4) et POST (2,0±0,4) ont été moins nombreuses que dans le groupe TEM (3,0±0,4). Le groupe PRE a donné des scores plus bas à l’EVA au repos à 15 et 24 h et lors de la toux à 24, 48, et 72 h après l’intervention, en comparaison avec les groupes TEM et POST.Conclusion: L’administration intraveineuse de 1 mg·kg−1 de flurbiprofène pendant l’anesthésie réduit les besoins d’analgésie postopératoire à la suite d’une hystérectomie abdominale. De plus, le flurbiprofène est plus efficace lorsqu’on l’adminsitre avant qu’après l’intervention chirurgicale.

Halothane and Enflurane Attenuate Pulmonary Vasodilation Mediated by Adenosine Triphosphate-sensitive Potassium Channels Compared to the Conscious State

Background: Adenosine triphosphate (ATP)‐sensitive potassium (K sup +ATP) channels play an important role in pulmonary vasoregulation. However, the effects of volatile anesthetics on K sup +ATP channel‐mediated pulmonary vasoregulation have not been elucidated. The purpose of the present study was to investigate the effects of halothane and enflurane anesthesia on the pulmonary vasodilator response to the selective K sup +ATP channel agonist lemakalim (BRL38227) compared with that measured in the conscious state. The authors also investigated the extent to which endogenous neurohumoral vasoconstrictor mechanisms modulate the vasodilator response to K sup +ATP channel activation. Method: Nineteen conditioned, male mongrel dogs were chronically instrumented to measure the left pulmonary vascular pressure‐flow (LPQ) relationship. LPQ plots were generated by continuously measuring the pulmonary vascular pressure gradient (pulmonary arterial pressure‐left atrial pressure) and left pulmonary blood flow during gradual (approximately 1 min) inflation of a hydraulic occluder implanted around the right main pulmonary artery. After preconstriction with the thromboxane analog, U46619 (9,11‐dideoxy‐11alpha, 9alpha ‐epoxymethano‐prostaglandin F2alpha), the pulmonary vascular dose‐response relationship for the K sup +ATP agonist lemakalim was assessed in the conscious and halothane‐anesthetized states and also in the conscious and enflurane‐anesthetized states. This protocol was repeated in conscious and halothane‐anesthetized dogs after combined neurohumoral block with antagonists of sympathetic alpha1 adrenoreceptors, arginine vasopressin V1 ‐receptors, and angiotensin II receptors. The effect of the K sup +ATP antagonist glybenclamide on the baseline LPQ relationship and on the lemakalim dose‐response relationship also was assessed in conscious dogs. Results: Compared with the conscious state, halothane, enflurane and glybenclamide had no net effect on the baseline LPQ relationship. In contrast, halothane and enflurane attenuated (P < 0.05) the pulmonary vasodilator response to lemakalim compared with the conscious state. Glybenclamide also caused a rightward shift (P < 0.05) in the lemakalim dose‐response relationship. Combined neurohumoral block did not modulate the vasodilator response to lemakalim in the conscious state. The halothane‐induced attenuation of the vasodilator response to lemakalim was apparent after combined neurohumoral block. Conclusion: These results indicate that halothane and enflurane act to reduce the magnitude of K sup +ATP channel‐mediated pulmonary vasodilation. Reflex pulmonary vasoconstriction resulting from K sup +ATP ‐mediated systematic hypotension does not alter the magnitude of the pulmonary vasodilator response to lemakalim nor is it responsible for the attenuated response to K sup +ATP channel activation during halothane anesthesia.

Atropine for the treatment of hiccup after laryngeal mask insertion.

IMPLICATIONS We describe three patients in whom hiccups were treated successfully by atropine. Although further clinical investigation is needed, atropine may be useful in the treatment of hiccups after the laryngeal mask airway insertion.

Cardioprotective effect and mechanism of action of landiolol on the ischemic reperfused heart.

PurposeThe authors examined the cardioprotective effect of landiolol, an ultra short-acting, highly selective β1-blocker, and its role in cardiac work, antioxidative effect, and sarcoplasmic reticulum (SR) function in hearts subjected to ischemia-reperfusion.MethodsIsolated guinea pig hearts were subjected to ischemia-reperfusion by stopping the perfusion for 45 min and reperfusing. Before the ischemia, hearts were treated with landiolol (20, 100, or 500 µM) for 15 min (LAN group). In another set of experiments, before ischemia, hearts were washed out for 15 min after treatment with landiolol (WO group). In other hearts, the tissue concentration of malondialdehyde was measured after reperfusion. We also examined the phosphorylation of phospholamban at Ser16 and Thr17residues to evaluate the SR function.ResultsAfter 90 min of reperfusion, left ventricular pressure (LVP) was restored significantly in the LAN-500 µM group regardless of heart rate. However, the improvement in recovery in LVP disappeared in the WO group. The tissue malondialdehyde levels were decreased in the LAN group compared with those in the control group. In the control group, the phosphorylation of phospholamban at Ser16 and Thr17 residues was markedly increased after reperfusion. Landiolol at 500 µM suppressed the increase of phosphorylation at Ser16 residues.ConclusionThe present study demonstrated that landiolol had a lipid peroxidation-reducing effect and suppressed the increase in phospholamban phosphorylation at the Ser16 residue in hearts subjected to ischemia-reperfusion. These findings indicate that landiolol may have an anti-ischemic effect, via an antioxidant effect and/or via preserving SR function during the ischemic period.