A large individual variation in both the infusion rate and the blood concentration of rocuronium necessary for obtain adequate surgical muscle relaxation during total intravenous anesthesia with propofol and remifentanil.

BACKGROUND: Rocuronium (Rb) is ideal for continuous infusion but has a widely variable duration of action. We investigated the distribution of Rb infusion in a steady state of optimal muscle relaxation and the relationship between the measured and predicted blood Rb concentrations in laparoscopic surgery. METHODS: Seventeen patients were anesthetized with propofol. Continuous Rb infusion was commenced at 7.5 µg/kg/min from 15 min after an initial Rb injection (0.6 mg/kg) and adjusted every 15 min to keep T1 within 3-10 %. Blood concentration was measured at the first onset of steady state, predicted concentration was calculated pharmacokinetically, and 25 % recovery time was measured. The distribution of the predicted concentration and infusion rate was plotted by histogram, the median value and 95th percentile were calculated, and the relationship between measured and predicted concentrations was analyzed by regression analysis. RESULTS: The rate during the stable state was 7.3 ± 2.1 µg/kg/min on average, 4 at minimum, 12 at maximum, and 12 at the 95th percentile. The predicted concentration was 1.7 ± 0.5 µg/ml on average, 0.8 at minimum, and 2.9 at maximum. The mean measured concentration was 1.4 ± 0.4 µg/ml. The predicted concentration was proportional to the measured concentration (y = 0.91x, r = 0.475; p < 0.001). A significant linear relationship was observed between the measured concentration and infusion rate (y = 0.64 + 0.11x, r = 0.618; p < 0.05). CONCLUSION: The measured blood concentration of Rb was comparable to the predicted value. Anesthesiologists can avoid overdose and attain a reliable muscle relaxant effect by maintaining a continuous dose by titration according to individual differences under muscle relaxant monitoring.

Inhibition of insulin secretion from rat pancreatic islets by dexmedetomidine and medetomidine, two sedatives frequently used in clinical settings.

The aim of this study was to determine whether dexmedetomidine (DEX) and medetomidine (MED), α2-adrenergic agonists clinically used as sedatives, influence insulin secretion from rat pancreatic islets. Islets were isolated from adult male Wistar rats after collagenase digestion. Static incubation was used to determine effects of DEX or MED on insulin secretion and ionic-channel currents of ß-cells. Results indicate that both drugs dose-dependently inhibit insulin secretion, DEX more potently than MED. The inhibitory effects were attenuated by addition of yohimbine or by pretreatment of rats with pertussis toxin (PTX). 10 nM DEX decreased the current amplitude of voltage-dependent Ca2+ channels, but this did not occur when the N-type Ca2+ channel blocker ω-conotoxin was added. In the presence of tetraethylammonium, a classical voltage-gated K+ channel (Kv channel) blocker, the magnitude of inhibition of insulin secretion by MED was reduced. However, when tolbutamide, a specific blocker of the ATP-sensitive K+ channel (KATP channel), was present, the magnitude of MED inhibition of insulin secretion was not influenced, suggesting that Kv-channel activity alteration, but not that of KATP channels, is involved in MED-associated insulin secretory inhibition. The Kv-channel currents were increased during 1 nM MED exposure at membrane potentials ranging from -30 mV to -10 mV, where action potentials were generated in response to glucose stimulation. These results indicate that DEX and MED inhibit insulin secretion through an α2-adrenoceptor and PTX-sensitive GTP-binding protein pathway that eventually involves Kv channel activation and Ca2+ channel inhibition.

Arytenoid adduction combined with medialization laryngoplasty under general anesthesia using a laryngeal mask airway.

PURPOSE: Laryngeal framework surgery is usually performed under local anesthesia but cannot be tolerated by some patients. To develop a new procedure for these patients, we evaluated voice outcomes after arytenoid adduction combined with medialization laryngoplasty under general anesthesia using a laryngeal mask airway (LMA) for unilateral vocal cord paralysis. MATERIALS AND METHODS: Eleven consecutive patients with severe unilateral vocal cord paralysis, with a maximum phonation time of less than 5 seconds, underwent arytenoid adduction combined with medialization laryngoplasty under general anesthesia using an LMA. Each paralyzed vocal cord was observed by intraoperative videolaryngoscopy. The vocal cord was moved to the position where the best vocal outcome could be expected, according to 3 parameters obtained from glottal images. RESULTS: All patients achieved a maximum phonation time of more than 11 seconds. The mean airflow rate, which ranged from 550 to 1000 mL/s before surgery, improved to less than 390 mL/s. Perceptual evaluation using the grade, roughness, breathiness, asthenia and strain scale also improved significantly. CONCLUSIONS: These results were equivalent to those of previous reports of surgeries performed under local anesthesia. Intraoperative endoscopic vocal cord observation through the LMA may have contributed to the positive results.

[Emergency coronary artery bypass grafting for acute coronary syndrome].

Since the drug eluting stents appeared in Japan, the indication for percutaneous coronary intervention has become wide-spread for the treatment of coronary artery disease. In the past decade, 216 patients underwent emergency/urgent coronary artery bypass grafting (CABG) in our institution, while the annual numbers of both emergency and elective CABG cases have declined. On the contrary to the decreasing number, emergency CABG patients were significantly getting older with multiple co-morbidities. Thus, off-pump CABG is likely to be beneficial for preventing postoperative complications, leading to the decreased postoperative mortality. When emergency CABG patients developed refractory myocardial ischemia and unstable hemodynamics, a percutaneous cardiopulmonary support system was quickly applicable and useful for on-pump beating CABG achieving complete surgical revascularization. For keeping satisfactory hemodynamics during CABG, communication between cardiovascular surgeons, anesthesiologists, and perfusionists is most important.

[Comparison of two methods of local anesthetic administration using three phantom tissue models].

BACKGROUND: Local anesthetic is often administered around surgical wounds to reduce pain. It remains unknown, however, how the agent diffuses into tissue, or whether the method of administration has any impact on the drug diffusion. We evaluated drug-diffusion areas around wounds after administering a dummy agent by needle injection (NI) and direct infiltration (DI) using three phantom tissue models : agar, sponge, and pork rib. METHODS: Blue-colored water, a dummy substitute for local anesthetic, was administered in the vicinity of surgical wounds simulated by three tissue models. After the administration, blue-stained cross sectional areas and diffusion capacities were compared. RESULTS: The stained cross sections of the DI tissue were uniform, while those of the NI tissue were globular and centered around the needle point. The sectional area and diffusion capacity were significantly greater in the DI tissue than in the NI tissue in the agar model, though no significant differences between the administration methods were observed in the other models. CONCLUSIONS: The direct infiltration method is likely to diffuse local anesthetic into tissue more uniformly and more extensively than the needle injection method.

Intracranial hemorrhage associated with cerebrospinal fluid drainage during thoraco-abdominal aortic surgery.

A 69-year-old woman underwent thoraco-abdominal aortic aneurysm repair with cerebrospinal fluid drainage (CSFD). The initial CSF pressure was elevated to approximately 25 cmH(2)O, and clear CSF was continuously drained at a rate of 30 ml/h with the drainage level at 10-20 cmH(2)O. The CSF became bloody when cardiopulmonary bypass was terminated. The total volume of CSF drained was approximately 300 ml at the conclusion of the 638 min operation. Three hours later, she suffered a series of generalized seizures because of intracranial hemorrhage (ICH). It was suggested that excessive drainage of CSF was associated with ICH. Meticulous control of drainage volume combined with standard pressure-based management may be the key to avoiding these complications.

Effects of low-dose atrial natriuretic peptide infusion on cardiac surgery-associated acute kidney injury: A multicenter randomized controlled trial.

PURPOSE: To evaluate the effects of atrial natriuretic peptide (ANP) on renal function and medical costs in patients with acute kidney injury (AKI) associated with cardiac surgery. MATERIALS AND METHODS: The Japanese trial for AKI in Post-cardiovascular surgery patients by ANP (JAPAN) was a prospective, multicenter, randomized, double-blind, placebo-controlled study conducted in 11 hospitals in Japan. Acute kidney injury was defined as an increase in serum creatinine of at least 0.3 mg/dL within 48 hours. The patients were randomly assigned to receive ANP (0.02 µg kg-1 min-1) or placebo. The primary end point was a change in renal function. The secondary end points were a need for renal replacement therapy, the lengths of intensive care unit and hospital stays, and medical costs incurred over the 90-day follow-up. RESULTS: Of the 77 randomized patients, 37 were in the ANP group and 40 were in the placebo group. Although ANP significantly (P = .018) increased urine output, it did not significantly improve renal function compared with placebo. There were no significant differences between the groups in the renal replacement therapy rate, the lengths of the intensive care unit and hospital stays, or medical costs. CONCLUSION: Atrial natriuretic peptide infusion did not show a renoprotective effect or cost-saving effect in the treatment of cardiac surgery-associated AKI.

[Anesthetic management for infected abdominal aneurysm].

A 48-year-old man was scheduled for repair of mycotic abdominal aortic aneurysm. Extraanatomic bypass was performed due to infection of the aneurysm. General anesthesia combined with continuous epidural anesthesia was performed. In spite of severe blood loss, hemodynamic state was stable during anesthesia and postoperative period. He was managed in the intensive care unit without any complication. In this anesthetic management, it is very important to maintain adequate cardiac output and circulating blood volume to prevent visceral ischemia.

[Successful airway management using a Cook airway exchange catheter as an emergent dilator for life-threatening neoplastic stenosis of the trachea: a case report].

A 68-year-old male patient was referred to our hospital for his intractable and progressive dyspnea. Chest roentgenography and computerized tomography revealed severe lower tracheal stenosis due to neoplastic invasion. The tumor completely surrounded his trachea for 5 cm length and the remaining internal diameter of the trachea was less than 5 mm. To avoid fatal asphyxia, emergency airway security was required. After placing both femoral arterial and venous cannulae for percutaneous cardiopulmonary support system, we dilated the stenotic trachea using a Cook airway exchange catheter (CAEC), and then an armored tube of 7 mm inner diameter was introduced through the CAEC. The maneuver was smoothly completed within one minute without any complications. His dyspnea was completely relieved. Following chemotherapy and radiotherapy were so effective that the endotracheal tube was extubated two weeks later uneventfully. After several series of chemotherapy and 50 Gy irradiation, the patient was discharged three months later without symptoms. We concluded that CAEC could be one of the life-saving instruments for emergent airway management in case of severe organic tracheal stenosis.

Contralateral pulmonary edema following surgical repair of a ruptured hemidiaphragm.

A 24-year-old man underwent surgical correction of a ruptured hemidiaphragm via left thoracotomy and laparotomy. During the procedure, he developed contralateral pulmonary edema that completely resolved after four days of mechanical ventilatory support. Instantaneous unilateral pulmonary edema should be considered in young patients with thoracic compliance abnormalities.

Effect of N-methyl-D-aspartate receptor epsilon1 subunit gene disruption of the action of general anesthetic drugs in mice.

BACKGROUND: Recent molecular strategies demonstrated that the N-methyl-d-aspartate (NMDA) receptor is a major target site of anesthetic agents. In a previous article, the authors showed that knocking out the NMDA receptor epsilon1 subunit gene markedly reduced the hypnotic effect of ketamine in mice. In the current study, the authors examined the in vivo contribution of the NMDA receptor epsilon1 subunit to the action of other anesthetic drugs. METHODS: The authors determined the anesthetic effects of nitrous oxide on sevoflurane potency in NMDA receptor epsilon1 subunit knockout mice compared with those in wild-type mice. They then tested the hypnotic effect of gamma-aminobutyric acid-mediated agents, such as propofol, pentobarbital, diazepam, and midazolam, in knockout mice and wild-type mice. RESULTS: The anesthetic action of sevoflurane itself was unaffected by the abrogation of the NMDA receptor epsilon1 subunit. Adding nitrous oxide reduced the required concentration of sevoflurane to induce anesthesia in wild-type mice, whereas this sparing effect was diminished in knockout mice. Furthermore, propofol, pentobarbital, diazepam, and midazolam also had markedly attenuated effects in knockout mice. CONCLUSIONS: Although it has been demonstrated that knocking out the expression of receptors may induce changes in the composition of the subunits, the network circuitry, or both, the current findings show consistently that the NMDA receptor epsilon1 subunit mediates nitrous oxide but not sevoflurane anesthesia. Furthermore, the attenuated anesthetic impact of propofol, pentobarbital, diazepam, and midazolam as well as ketamine in knockout mice suggests that the NMDA receptor epsilon1 subunit could be indirectly involved in the hypnotic action of these drugs in vivo.

Relationship between symptoms of ischemic heart disease and upper abdominal digestive organ disease.

We previously reported that percutaneous trans-arterial coronary angioplasty (PTCA) seemed to decrease cardiac complications in patients with ischemic heart disease (IHD) who underwent abdominal surgery. After the report, 1293 PTCAs were performed for patients with IHD in our institute. Of these 1293 patients, 6 patients underwent abdominal surgery under general anesthesia within 14-150 days after successful PTCA. We observed the relationship between symptoms of IHD and upper abdominal digestive organ disease (ADOD), which sometimes occurs concomitantly in IHD patients. In conclusion, the present study identified some features of the chief complaints and symptoms of IHD patients with concomitant upper ADOD. This information should prove useful for making a differential diagnosis and deciding treatment.