Koichi Futagawa

Anesthetic management for the minimally invasive Nuss procedure in 21 patients with pectus excavatum

The aim of this study was to assess the anesthetic management and postoperative analgesic effect of continuous epidural infusion for the minimally invasive Nuss procedure. A total of 21 operated cases were analyzed retrospectively. Thoracoscopy was used in all cases. General anesthesia with endotracheal intubation was induced and maintained with oxygen, air, sevoflurane, and fentanyl in all cases. Thoracic epidural anesthesia was performed after induction at the level between Th4 and 12. When the bar was placed via insertion under the sternum, six patients exhibited sinus tachycardia and one showed premature atrial contraction for 2–4 beats before recovering spontaneously within 1 min. Operations were uneventful. The mean operating time was 115 min and anesthetic time was 193 min. In X-ray findings, residual pneumothorax and pleural effusion were found in seven (33.3%) and eight (38.0%) patients, respectively. In all cases, these symptoms were resolved spontaneously within 5 days. Epidural fentanyl (0.3 µg·kg−1·h−1) in 0.125% bupivacaine (0.15 ml·kg−1·h−1) or 0.2% ropivacaine (0.15 ml·kg−1·h−1) were used for 3 days to relieve postoperative pain. Postoperatively, 12 (57.1%) patients required no additional analgesics, and 4 (19.0%) patients required a single dose of dicrofenac sodium or pentazocine. Although the Nuss procedure is minimally invasive, we should pay attention to the possibility of many intra- and postoperative complications. Continuous epidural infusion of fentanyl with local anesthetics provides effective postoperative pain relief and prevents complications such as bar displacement after the Nuss procedure.

Volatile anesthetics constrict pulmonary artery in rabbit lung perfusion model

Volatile anesthetics are generally considered to possess a vasodilator action. Some of their actions on pulmonary vessels, however, are not clearly understood. We examined the effects of various volatile anesthetics on pulmonary vessels using an in situ rabbit isolated-lung perfusion model. We prepared a rabbit constant-flow lung-perfusion model by sending blood to the pulmonary artery and removing blood from the left atrium, and observed the changes in pulmonary arterial perfusion pressure caused by inhalation of 0.5, 1, 2, and 3 minimum alveolar concentration (MAC) volatile anesthetics: halothane, enflurane, isoflurane, and sevoflurane, in random order. These volatile anesthetics increased pulmonary arterial perfusion pressure in a dose-dependent manner and caused the pulmonary arteries to constrict. In particular, halothane at all concentrations induced significantly greater pulmonary vasoconstriction than the other volatile anesthetics. Therefore, it is suggested that volatile inhalation anesthetics induce the pulmonary arteries to constrict, and halothane exhibits the most potent pulmonary vasoconstrictor effect among the volatile anesthetics tested.

Roles of endotracheal tubes and slip joints in respiratory pressure loss: a laboratory study

PurposeThe endotracheal tube (ETT) constitutes a significant component of total airway resistance. However, a discrepancy between measured and theoretical values has been reported in airway resistance through ETTs. The causes of the discrepancy were estimated by physical and rheological simulations.MethodsThe pressure losses through total lengths of ETTs and slip joints under a volumetric flow rate of 30 L/min were measured, and the pressure losses through the tubular parts of ETTs with internal diameters (IDs) of 6.0-, 6.5-, 7.0-, 7.5-, and 8.0 mm were measured. The Reynolds number of each setting was calculated, and the pressure losses through the total length of the ETT, the tubular part, and the slip joint of each size of tube were estimated.ResultsThe Reynolds numbers were >5000 in all sizes of ETTs. Measured pressure losses were larger in small sized ETTs than in large sized ETTs—520.9 Pascals (Pa) in 6.0-mm ID and 136.4 Pa in 8.0-mm ID tubes. The measured pressure losses through the tubular part were comparable to the predicted values. The measured pressure losses through the slip joints were larger than the predicted values, and they accounted for approximately 25–40% of total pressure losses of the ETTs.ConclusionEspecially in small sized tubes, the pressure loss through the slip joint accounts for a large percentage of the total pressure loss through the ETT. The pressure loss through the slip joint may play a role in the discrepancy between measured and theoretical pressure losses through ETTs.

Thermophysical Properties of Thermosoftening Nasotracheal Tubes

Thermosoftening treatment of polyvinyl chloride (PVC) nasotracheal tubes (NTTs) can reduce the incidence and amount of epistaxis during nasotracheal intubation. The optimal thermal setting for thermosoftening treatment of NTTs without burn injury was investigated. Two composite types of PVC NTTs were used. Following withdrawal of the PVC NTTs from a bottle of water at 45 or 60°C, the changes in the surface temperature of the NTTs were measured by infrared thermography. Hardness of the NTTs at 25, 30, 35, and 40°C was measured. The incidence of epistaxis during nasotracheal intubation using thermosoftened NTTs was evaluated retrospectively. The surface temperature of both PVC NTTs dipped in 45 and 60°C water decreased to below body temperature 30 seconds after withdrawing them from the bottles. Although thermosoftening treatment proportionally decreased the hardness of both types of NTTs, the degrees differed according to their composition. When avoiding impingement of the NTT on the posterior wall of the nasopharynx, the incidence of mild and moderate epistaxis was 2.3%. Flexibility of PVC NTTs could be obtained by thermosoftening treatment at 60°C without burn injury. Thermosoftening treatment of PVC NTTs may be useful to avoid epistaxis during nasotracheal intubation.