Optimal doses of sevoflurane and propofol in rabbits.

BACKGROUND: Although sevoflurane and propofol are commonly used anesthetics in rabbits, optimal doses of remain unclear. We thus assessed the optimal hypnotic doses of sevoflurane and propofol, and evaluated the influence of dexmedetomidine on sevoflurane and propofol requirements. METHODS: Twenty-eight Japanese white rabbits were randomly assigned to one of four groups (n=7 each). Rabbits were given either sevoflurane, propofol, sevoflurane+dexmedetomidine, or propofol+dexmedetomidine (injected 30 µg∙kg(-1)∙hr(-1) for 10 min followed by an infusion of 3.5 µg∙kg(-1)∙hr(-1)). Hypnotic level was evaluated with Bispectral Index (BIS), a well-validated electroenchalographic measure, with values between 40 and 60 representing optimal hypnosis. BIS measurements were made 10 minutes after the adjustment of target end-tidal sevoflurane concentration in the sevoflurane group and sevoflurane+dexmedetomidine group, and at 10 min after the change of infusion rate in the propofol group and propofol+dexmedetomidine group. RESULTS: BIS values were linearly related to sevoflurane concentration and propofol infusion rate, with or without dexmedetomidine. Sevoflurane concentration at BIS=50 was 3.9±0.2% in the sevoflurane group and 2.6±0.3% in the sevoflurane+dexmedetomidine group. The propofol infusion rate to make BIS=50 was 102±5 mg∙kg(-1)∙hr(-1) in the propofol group, and 90±10 mg∙kg(-1)∙hr(-1) in the propofol+dexmedetomidine group. CONCLUSIONS: The optimal end-tidal concentration of sevoflurane alone was thus 3.9%, and optimal infusion rate for propofol alone was 102 mg∙kg(-1)∙hr(-1). Dexmedetomidine reduced sevoflurane requirement by 33% and propofol requirement by 11%.

High-frequency jet ventilation during video-assisted thoracoscopic surgery in a patient with previous contralateral pneumonectomy.

A case of high-frequency jet ventilation (HFJV) during video-assisted thoracoscopic surgery (VATS) in a patient with previous contralateral pneumonectomy is presented. A 77-year-old man with a right pneumothorax was scheduled for bullectomy by VATS. He had undergone left pneumonectomy due to lung cancer 6 years earlier. Anesthesia was induced and maintained with propofol and fentanyl. The patient was intubated with a normal, single-lumen endotracheal tube (ETT). HFJV was applied through the ETT during the VATS procedure. Although PaCO(2) gradually increased from 51.9 mmHg to 80.0 mmHg, appropriate surgical conditions were provided, PaO(2) was well preserved, and blood pressure and heart rate were stable throughout the VATS procedure.

[Epidural fentanyl delayed emergence from anesthesia].

An 83-year-old man (158 cm, 42 kg) was scheduled for cholecystectomy. He had a history of hypertension and atrial fibrillation. The patient received no premedication. An epidural catheter was inserted via the T9-10 interspace and 2% mepivacaine 7 ml was injected, producing a sensory block from T4 to T12. Anesthesia was induced with propofol and remifentanil, and was maintained with propofol, remifentanil, and nitrous oxide in oxygen. Rocuronium was given to provide neuromuscular block. Just before the completion of surgery, a bolus epidural injection of 2% mepivacaine 2 ml with fentanyl 50 microg was performed. Then epidural solution of ropivacaine 0.1% with fentanyl 6.25 microg x ml(-1), and droperidol 25 microg x ml(-1) was infused at 4 ml x hr(-1). Soon after the surgery, the patient developed atrial fibrillation that was treated with external electrocardioversion with 100 watt x sec. After the restoration of sinus rhythm, anesthetics were discontinued. The patient did not emerge from anesthesia though he breathed spontaneously Doxapram was slightly effective, but he did not respond to the verbal command. Epidural infusion was stopped and the patient was transferred to the ward. The patient fully recovered from anesthesia after 2 hours. Epidural infusion was restarted 17 hours later, and the patient fell asleep. He woke up after stopping epidural infusion. Epidurally administered fentanyl must have been the cause of delayed recovery from anesthesia. He could have been highly sensitive to fentanyl. Patient controlled epidural anesthesia may have been useful for this patient.

Cardiac arrest after spinal anesthesia in a patient with neurally mediated syncope.

We present the case of cardiac arrest in a patient with neurally mediated syncope (NMS). A 66-year-old male patient was scheduled to undergo right inguinal hernioplasty. He had a history of syncope, which occurred a few times a year in childhood and once a year recently. One minute after the second spinal injection, cardiac arrest (asystole) developed. Sinus rhythm was restored by cardiac massage and intravenous administration of atropine and ephedrine. The operation was cancelled. The patient was diagnosed as NMS by a cardiologist. Four months later, right inguinal hernioplasty was performed, uneventfully, under general anesthesia. High sympathetic blockade due to spinal anesthesia and transient withdrawal of sympathetic tone and increase in vagal discharge due to NMS could be the main causes of the cardiac arrest. If the patient has any possibility of NMS, anesthesiologists should consider the possibility of cardiac arrest after spinal anesthesia.

[Case report of using a connector (phycon TCB bronchial blocker) for pediatric one-lung anesthesia].

We report a case of using a connector (Phycon TCB Bronchial Blocker: Fuji Systems) in pediatric one-lung anesthesia. An eight-year-old boy with mid-mediastinal tumor was scheduled for video-assisted thoracoscopic surgery. After tracheal intubation with normal tracheal tube, we connected the connector and confirmed a 5 Fr Fogarty catheter through the tube under fiberoptic visualization. We were able to achieve one-lung ventilation. The operation was uneventful. This connecter is easy to fix and release the catheter. It is useful to modify the catheter position during one lung ventilation for pediatric patients.