[A case of previously undiagnosed methemoglobinemia exhibiting sustained low SpO2 value at the induction of general anesthesia].

A 70-year-old woman was scheduled to undergo surgery for removal of thyroid tumor under general anesthesia. A routine preoperative evaluation confirmed that the patient was stable with no signs of cyanosis and dyspnea. However, during pre-oxygenation as well as mechanical ventilation with 100% oxygen, she showed sustained low SpO2 values (i.e., 91%). Arterial blood gas analysis at FIO2 of 1.0 showed an oxygen partial pressure (PaO2) of 297 mmHg. Unexpectedly, the analysis revealed methemoglobinemia (MetHb concentration: 15%) causing a discrepancy between the low SpO2 and normal PaO2 values in this patient. Methemoglobinemia is an uncommon cause of cyanosis; however, anesthesiologists should be aware that some drugs used during perioperative period (e.g., local anesthetics) can cause methemoglobinemia. While our case was a mild one and the patient recovered with no complications, methemoglobinemia levels above 30% could cause tissue hypoxemia and, thereby, requiring a treatment with methylene blue or ascorbic acid.

Oral gastric tube-guided insertion of the ProSeal™ laryngeal mask is an easy and noninvasive method for less experienced users.

PURPOSE: The ProSeal™ laryngeal mask airway (PLMA) can be more difficult to insert than the classic laryngeal mask, especially in patients who have a thin palate with a steep oropharyngeal curve. Here, an oral gastric (OG) tube-guided technique is considered as a method that makes it easier to successfully insert a PLMA. METHODS: Sixty patients who were scheduled to undergo general anesthesia without neuromuscular blocking were randomly allocated into two groups: 30 patients with PLMA inserted by the standard digital technique, and 30 with the PLMA inserted by an OG tube-guided technique. Most PLMA insertions were performed by less experienced users. The success rate at the first attempt, the time taken to insert the PLMA, the difficulty of the procedure, and the incidence of oropharyngeal trauma and postoperative sore throat were compared between the two groups. RESULTS: PLMA insertion was successfully achieved at the first attempt using the OG tube-guided technique in all 30 patients. The OG tube-guided insertion required fewer attempts (P = 0.04) and led to a less difficult insertion procedure (P = 0.02) than the standard digital insertion. Effective ventilation during anesthesia was achieved in all patients, with a lower mean cuff pressure in the OG tube-guided technique group (P = 0.02). The frequency of blood sticking to the PLMA tube (P < 0.001) and the incidence of postoperative sore throat (P = 0.003) were lower in the OG tube-guided group than the standard digital technique group. CONCLUSIONS: OG tube-guided PLMA insertion is easier for less experienced users, trainees, and experts as well as less invasive for patients than the standard digital insertion.

[Internal jugular vein cannulation guided by pulsation].

BACKGROUND: We are accustomed to right internal jugular vein (IJV) cannulation guided by pulsation for 20 years or more. This study was conducted to evaluate whether this method is a safe and certain method. METHODS: After obtaining informed consent, 100 elective surgical patients requiring central venous catheterization during perioperative period were randomly assigned to either the pulsation group in which IJV pulsation was used for a landmark of puncture or the US group in which IJV was recognized with ultrasonography before puncture. RESULTS: Pulsation was observed in 98 patients. Successful rate of first attempt with a 23 G seeking needle was 85.7% in the pulsation group and 86% in the US group. IJV was successfully cannulated at 1 pass in the entire pulsation group and 92% in the US group. The frequency of puncture with cannula was significantly lower in the pulsation group than that of the US group. Arterial puncture with the seeking needle was recorded in 3 patients in the US group. Successful rate of first attempt in this study was comparable to other studies using ultrasonographic guidance. CONCLUSIONS: Internal jugular vein cannulation by pulsation method is a safe and certain method.

[Remifentanil provides fast recovery and hemodynamic stability in laryngomicrosurgery anesthesia].

BACKGROUND: Stressful procedures such as intratracheal intubation and direct laryngoscopy in very short operations make anesthetic management for laryngomicrosurgery difficult. This study was conducted to evaluate which anesthetic agent, remifentanil or fentanyl, is suitable in anesthesia for laryngomicrosurgery. METHODS: After obtaining informed consent prior to the study, 18 patients undergoing elective laryngomicrosurgery were randomly allocated to one of two groups to receive remifentanil (R group) or fentanyl (F group). Patients with ages above 76 years and moderate abnormalities in cardiovascular system or respiratory system were excluded. RESULTS: Average infusion rate of remifentanil was 0.24 +/- 0.02 microg x kg(-1) x min(-1) and total infused dose of fentanyl was 0.27 +/- 0.05 mg. Average bispectral index values in both groups were comparable. Cases needing sevoflurane inhalation to control blood pressure were significantly more in F group than in R group. Heart rate was significantly lower in R group than in F group. Duration from the end of operation to responses to verbal commands and extubation was significantly shorter in R group than in F group. CONCLUSIONS: Remifentanil provided faster recovery and hemodynamic stability. Therefore, remifentanil seems to be more suitable than fentanyl in anesthesia for laryngomicrosurgery.

[Prophylactic strategies for perioperative pulmonary thromboembolism in cancer patients].

BACKGROUND: Our previous reports showed that elastic stockings (ES) combined with intermittent pneumatic compression (IPC) significantly decrease the incidence of perioperative pulmonary thromboembolism (PTE). This study was conducted to investigate whether ES with IPC is useful to prevent PTE in cancer patients. METHODS: No prophylactic strategies were employed from January 1998 to December 1999 (4511 cases). ES combined with ICP apparatuses was employed from May 2000 to April 2008 (20,383 cases). Details of the methods were described in our previous reports. RESULTS: Age, anesthesia duration and operation duration increased statistically without clinical significances after the induction of prophylactic strategies. About 90 per cent of surgical patients had malignant disease. Seven patients developed PTE without any interventions and 5 patients with treatments. The incidence of PTE decreased significantly from 15.51 persons/10,000 cases to 2.45 persons/10,000 cases. Cardiac arrest occurred in two untreated patients but in no treated patient. Intervention also significantly decreased the incidence of cardiac arrest. CONCLUSIONS: The combination of ES and ICP seems to be useful to decrease the incidence and severity of perioperative PTE in cancer patients in Japan.

[Intra-atrial vegetation removal in a 14-month-old boy complicated with postoperative infective endocarditis and left middle cerebral artery embolism].

We report a case of the intra-atrial vegetation removal under cardiopulmonary bypass (CPB) in a case complicated with left middle cerebral artery embolism caused by postoperative infective endocarditis. The patient was a 14-month-old boy. Two months after intracardiac repair for a complex congenital heart disease, he presented with low-grade fever and was placed on oral antibiotics. A month later an echocardiography revealed 2 vegetations on the tricuspid valve. Although the vegetations became smaller with intravenous antibiotics, right hemiplegia was noted 5 weeks later. Brain CT and MR-angiography demonstrated left middle cerebral artery embolism. For fear of another embolism caused by a remaining movable vegetation on the tricuspid valve, intra-atrial vegetation removal under CPB was performed 5 days after cerebral infarction. Intraoperative transesophageal echocardiography was utilized to locate the vegetation and confirm its removal. His postoperative course was uneventful without a recurrence of cerebral infarction or bleeding. He was weaned from the ventilator on postoperative day (POD) 1, started to move the right extremities on POD 5 and was discharged home on POD 66.

[Perioperative management of airway foreign bodies in 35 pediatric patients].

We retrospectively reviewed 33 patients (35 cases) who underwent foreign body removal at our institution from 1995 through 2003. Male-female ratio was 21 : 12 and the most frequent age was one year. The most common foreign bodies (FBs) were nuts (n = 14) and plastics (n = 7). A repeater (3 cases) had mental retardation. Patients were referred to our institution with an average interval of 90 hours, and after 1.3 hospitals. All the patients were managed with general anesthesia. Direct laryngoscopy was performed to extract FBs in 11 cases suspected of having pharyngeal or laryngeal FBs. In 24 cases suspected of having tracheobronchial FBs, the trachea was intubated and a flexible fiberoptic bronchoscopy was performed to locate the FBs. FBs were found in the trachea in 2 cases and in the bronchus in 18 patients and were successfully extracted by rigid bronchoscopy in 10 cases. All the patients were admitted for fear of laryngotracheal edema. There were no significant postoperative complications.

[Perioperative management for laparoscopic repair of congenital duodenal atresia].

BACKGROUND: Laparoscopic surgery has been applied even to neonates. To examine the safety and efficacy of laparoscopic repair of neonatal congenital duodenal atresia, we compared the 5 laparoscopic cases with the 5 conventional surgical cases. METHODS: The charts were retrospectively reviewed to investigate the anesthetic management, perioperative status and complications in the most recent 5 cases each of laparoscopic and conventional surgeries. RESULTS: There was a tendency to avoid laparoscopic repair in the patients with congenital heart disease. There were no intraoperative complications in both groups. Laparoscopic group exhibited less blood loss but longer operation time. In the two out of five laparoscopic cases re-operation was required due to technical issues, and the group needed a longer period before starting enteral feeding and longer hospitalization. CONCLUSIONS: Up to this time, laparoscopic repair of congenital duodenal atresia exhibited few advantages over conventional open repair.

Identification of the central imidazoline receptor subtype involved in modulation of halothane-epinephrine arrhythmias in rats.

We previously reported that imidazoline receptors in the central nervous system are involved in modulation of halothane-epinephrine arrhythmias. These receptors have been subclassified as I1 and I2 subtypes, but it is not known which receptor subtype is involved in halothane-epinephrine-induced arrhythmias. We designed the present study to clarify the involvement of central imidazoline receptor subtype in the modulation of halothane-epinephrine-induced arrhythmias. Rats were anesthetized with halothane and monitored continuously for systemic arterial blood pressure and premature ventricular contractions. The arrhythmogenic dose of epinephrine was defined as the smallest dose that produces three or more premature ventricular contractions within a 15-s period. Intracisternal moxonidine dose-dependently inhibited the epinephrine-induced arrhythmias during halothane anesthesia. Intracisternal efaroxan, a selective I1 antagonist with little affinity for I2 subtype, but not rauwolscine, an alpha2 antagonist without affinity for imidazoline receptors, blocked the antiarrhythmic effect of moxonidine. Intracisternal BU 224 and 2-BFI, selective I2 ligands, also inhibited the epinephrine-induced arrhythmias dose-dependently; however, these effects were abolished by efaroxan. We conclude that central I1, but not I2, receptors play an important role in inhibition of halothane-epinephrine arrhythmia.

[Anesthetic management of a 1.7-kg premature infant undergoing thoracoscopic thoracic duct ligation].

We report successful anesthetic management of a 1.7-kg premature infant who underwent thoracoscopic thoracic duct ligation under general anesthesia. She was born at 30 weeks gestation with birth weight of 1,546 g and was suffering from respiratory distress due to persistent right chylothorax for two months after birth. Chest tube drainage, fasting and intrapleural fibrin glue did not reduce her right chylothorax. Thoracoscopic thoracic duct ligation was scheduled on her day 64 under general anesthesia. The tracheal tube end was placed in the midtrachea and carbon dioxide was insufflated into the operative side of the thorax. During thoracoscopy her left lung was ventilated with the right lung pressed with spatulaes, but her respiratory status did not deteriorate so much despite of unilateral ventilation. We speculate that, due to massive right chylothorax, her pulmonary blood flow had already shifted to the left lung, therefore intraoperative substantial left unilateral lung ventilation exerted minimal effect on her respiratory status. The operation was successful and she was weaned from the ventilator on the following day.

[Anesthetic management of the ex-utero intrapartum treatment (EXIT) procedure for congenital high airway obstruction syndrome (CHAOS)].

We report an experience of anesthetic management of the ex-utero intrapartum treatment (EXIT) procedure performed in a fetus with congenital high airway obstruction syndrome (CHAOS) due to laryngeal atresia at 30 weeks' gestation. Anesthesia of the mother was induced with rapid sequence, and maintained with 3.5% sevoflurane in 100% oxygen and fentanyl before delivery. Two minimum alveolar concentration (MAC) sevoflurane provided excellent uterine relaxation without maternal hypotension. After hysterotomy, a sterile pulse oxymeter was placed on the fetus hand for monitoring fetal SpO2 and pulse rate, and a Doppler ultrasound transducer was applied to monitor fetal heart rate. Fentanyl (5 microg x dl(-1)) and pancuronium (0.2 mg x dl(-1)) were injected into the fetal upper arm in addition to transplacental anesthetic agents. The fetal heart rate and SpO2 were stable throughout the fetal manipulations, but the rise in SpO2 after initiating ventilation via tracheostomy was very slow. The uterine tone improved soon after discontinuing sevoflurane and oxytocin infusion was started after delivery. Surfactant administration before first ventilation is recommended in preterm babies undergoing EXIT procedure, and capnometer may be useful to confirm the adequate ventilation before cutting the umbilical cord.

Acute effects of direct cell implantation into the heart: a pressure-volume study to analyze cardiac function.

BACKGROUND: To safely implant cells into the myocardium, we must establish a volume that prevents compromising cardiac performance. We studied pressure-volume (PV) to investigate the adverse effects of direct cell implantation in the acute phase. METHODS: We used 21 minipigs. In the normal heart model, we studied PV by measuring various parameters (including end-systolic pressure, end-systolic elastance, dp/dtmax, end-diastolic volume, and time constant of isovolumetric left ventricular pressure fall [Tau]). We injected solutions into the left ventricular free wall (15 cm(2)). Sampling points were at baseline and after injection of saline (Group I, n = 4) or of blood (Group II, n = 4) at volumes of 1 ml and 10 ml up to 30 minutes after injection. In Group II, we injected additional blood (10 ml) 4 times. In the ischemic heart model, 1 month after ligating the left anterior descending artery, we injected 1 ml saline (Group III, n = 4), bone marrow mononuclear cells (10(8) cells/1 ml; Group IV, n = 4), or bone marrow stromal cells (10(8) cells/1 ml; Group V, n = 3). We studied PV before and after injection. RESULTS: In Group I, we found no significant changes in parameters. In Group II, end-diastolic volume after 10-ml injection (24.4 +/- 3.6 ml) was smaller than end-diastolic volume at baseline (29.5 +/- 5.8 ml, p < 0.01). Tau after 10-ml injection (39.4 +/- 5.3 msec) was greater than at baseline (35.6 +/- 4.0 msec, p < 0.01). One pig died of ventricular fibrillation after a 20-ml injection of blood. We observed no detrimental effects in Groups III, IV, and V. CONCLUSIONS: More than 10 ml cell suspension compromised diastolic function. We safely performed direct injection of bone marrow cells (1 x 10(8)/1 ml).

Nicorandil prevents epinephrine-induced arrhythmias in halothane-anesthetized rats by nitric oxide-dependent mechanism.

The effect of opening ATP-sensitive K(+) channels on the genesis of arrhythmias is still controversial. We investigated the effect of nicorandil, an ATP-sensitive K(+) channel opener, on the genesis of halothane-epinephrine arrhythmias in rats. We also clarified the involvement of nitric oxide in the effect of nicorandil. Furthermore, we studied the effect of levcromakalim, another ATP-sensitive K(+) channel opener, for comparison. Nicorandil and levcromakalim significantly increased the arrhythmogenic thresholds of epinephrine in a dose-dependent manner. On the other hand, nitroprusside, a potent vasodilator (5.0 micro g/kg per min), did not exert antiarrhythmic action significantly. Both glibenclamide (non-specific ATP-sensitive K(+) channel blocker) and 5-hydroxydecanoate (mitochondrial ATP-sensitive K(+) channel blocker) inhibited the antiarrhythmic action of nicorandil. Although pretreatment with N-omega-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthase inhibitor, did not modulate the genesis of halothane-epinephrine arrhythmias in the absence of nicorandil, it completely abolished the antiarrhythmic action of nicorandil, but not the effect of levcromakalim. We concluded that nicorandil dose-dependently inhibited halothane-epinephrine arrhythmias through mitochondrial ATP-sensitive K(+) channels and nitric oxide is required for the antiarrhythmic effect of nicorandil.

The effects of dexmedetomidine on the ventilatory response to hypercapnia in rabbits.

OBJECTIVE: Dexmedetomidine is a highly selective alpha(2)-adrenergic agonist that can reduce anesthetic requirements. This study, to assess its effect on respiration, examined the effects of various doses of dexmedetomidine (1, 10, 30 and 50 microg/kg) on the respiratory response to carbon dioxide (CO(2)) breathing in rabbits. DESIGN: Randomized prospective study. SETTING: Animal laboratory at a university school of medicine. INTERVENTION: From 28 animals, four groups of seven were randomly assigned to receive different doses of dexmedetomidine (groups D1, D10, D30 and D50). Under inhalation of sevoflurane, each animal was tracheostomized and intubated with a 4 mm internal diameter (i.d.) endotracheal tube. MEASUREMENTS AND RESULTS: After end-tidal sevoflurane concentration had decreased below 0.03% and during quiet breathing (QB); respiratory rate (RR), tidal volume (V(T)) and inspiratory time (T(I)) were measured, from which minute ventilation (MV) and mean inspiratory flow (V(T)/T(I)) were calculated. After these measurements had been completed, each animal breathed the balloon gas (5% CO(2) and 95% O(2)) until the end-tidal CO(2) (ETCO(2)) reached 10%. The respiratory measurements were repeated during the latter period. After the collection of these data, dexmedetomidine was infused intravenously and the same measurements were repeated 15 and 45 min after dexmedetomidine infusion. The slope of the ventilatory response to hypercapnia in D50 was significantly higher compared with D30 animals. In the range 1-30 microg/kg, during both QB and at 10% ETCO(2), MV was decreased in a dose-dependent manner. Dexmedetomidine depressed both V(T) and RR during QB and at 10% ETCO(2). CONCLUSION: Dexmedetomidine depressed resting ventilation and the respiratory response to CO(2), but it did not induce profound hypoxemia or hypercapnia in rabbits.

[Venoarterial bypass in children with congenital heart disease--a retrospective study].

To investigate prognostic factors for patients supported by venoarterial (VA) bypass, we analyzed retrospectively 31 patients with congenital heart diseases supported by VA bypass between 1997 and 2000. Median age was 3.6 months and median body weight was 4.0 kg. Causes of VA bypass were difficult weaning from cardiopulmonary bypass in 8 patients, postoperative cardiac dysfunction in 5 and cardiopulmonary resuscitation in 18. Six (19.4%) of 31 patients were weaned successfully from VA bypass, and 2 (6.5%) survived to hospital discharge. In patients who were weaned from VA bypass successfully, VA bypass was instituted more quickly (41.6 +/- 5.0 vs 62.5 +/- 35.9 min), and good tissue perfusion was established in association with lower lactate levels at 12 hr (7.0 +/- 5.9 vs. 16.4 +/- 15.4 mmol.l-1) and larger urine output during first 24 h (81 +/- 68 vs. 22 +/- 43 ml.kg-1.day-1), compared to those who failed to be weaned. Major complications were intracranial hemorrhage in the newborn (50%), and hypoxic brain damage in patients with palliative operation (35%). It is necessary to establish guidelines of entry, weaning, and withholding of this support.