Yusuke Sugasawa

Effects of sivelestat on bronchial inflammatory responses after esophagectomy.

Post-operative pulmonary complications such as systemic inflammatory response syndrome (SIRS), acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are strongly associated with morbidity and mortality after esophagectomy. Post-operative administration of sivelestat sodium hydrate (sivelestat), a selective inhibitor of neutrophil elastase (NE), has been shown to improve the post-operative clinical course after esophagectomy. This study aimed to evaluate the effect of prophylactic administration of sivelestat on bronchial inflammatory responses. We randomized 24 patients into two groups. One group received 0.2 mg/kg/h sivelestat from the induction of anesthesia to post-operative day 1 (sivelestat group) and the other group received the same amount of physiological saline (control group). Bronchial alveolar epithelial lining fluid (ELF) samples were obtained from both groups at the induction of anesthesia and at the end of surgery. The serum and ELF levels of interleukin (IL)-6 and IL-8 were measured by enzyme-linked immunosorbent assay, and NE activity was spectrophotometrically determined using the same samples. Although IL-6 levels in the ELF significantly increased at the end of surgery compared with the pre-operative levels in both groups, the IL-8 levels and NE activity did not significantly increase at the end of the surgery compared to the corresponding pre-operative values in the sivelestat group. Moreover, IL-8 levels and NE activity in the ELF were significantly reduced at the end of surgery in the sivelestat group compared with corresponding values in the control group. The durations of ALI and ARDS were apparently shorter in the sivelestat group and the duration of SIRS was significantly shorter in the sivelestat group compared to the control group. We demonstrated that prophylactic use of sivelestat mitigated bronchial inflammation by suppressing NE activity and IL-8 levels in the ELF and shortened the duration of SIRS after transthoracic esophagectomy.

Effects of nitrous oxide on the production of cytokines and chemokines by the airway epithelium during anesthesia with sevoflurane and propofol

The aim of this study was to evaluate the effects of nitrous oxide (a gaseous anesthetic) on the in vivo production of inflammatory cytokines and chemokines by the airway epithelium, when combined with sevoflurane or propofol. Subjects undergoing simple or segmental mastectomy were randomly assigned to the sevoflurane and nitrous oxide, sevoflurane and air, propofol and nitrous oxide, or propofol and air group (all n=13). Epithelial lining fluid (ELF) was obtained using the bronchoscopic microsampling method prior to and following the mastectomy to enable measurement of the pre- and post-operative levels of certain inflammatory cytokines and chemokines using a cytometric bead array system. Notably, the levels of interleukin (IL)-1β, IL-8 and monocyte chemotactic protein-1 (MCP-1) in the ELF were significantly increased following the operations which involved the inhalation of sevoflurane and nitrous oxide, although the levels of these molecules were not significantly changed by the inhalation of sevoflurane and air. Furthermore, the IL-12p70 levels were significantly reduced in the ELF following the operations that involved the inhalation of sevoflurane and air, although the IL-12p70 levels were not significantly changed by the inhalation of nitrous oxide and sevoflurane. These observations suggest that the combination of sevoflurane and nitrous oxide induces an inflammatory response (increased production of IL-1β, IL-8 and MCP-1) and suppresses the anti-inflammatory response (reduced production of IL-12p70) in the local milieu of the airway. Thus, the combination of these compounds should be carefully administered for anesthesia.

Effects of the volatile anesthetic sevoflurane on tonic GABA currents in the mouse striatum during postnatal development.

The volatile anesthetic sevoflurane, which is widely used in pediatric surgery, has proposed effects on GABAA receptor‐mediated extrasynaptic tonic inhibition. In the developing striatum, medium‐sized spiny projection neurons have tonic GABA currents, which function in the excitatory/inhibitory balance and maturation of striatal neural circuits. In this study, we examined the effects of sevoflurane on the tonic GABA currents of medium spiny neurons in developing striatal slices. Sevoflurane strongly increased GABAA receptor‐mediated tonic conductance at postnatal days 3–35. The antagonist of the GABA transporter‐1, 1‐[2‐[[(diphenylmethylene)imino]oxy]ethyl]‐1,2,5,6‐tetrahydro‐3‐pyridinecarboxylic acid hydrochloride further increased tonic GABA conductance during the application of sevoflurane, thereby increasing the total magnitude of tonic currents. Both GABA (5 μm) and 4,5,6,7‐tetrahydroisoxazolo[5,4‐c]pyridine‐3‐ol hydrochloride, the δ‐subunit‐containing GABAA receptor agonist, induced tonic GABA currents in medium spiny neurons but not in cholinergic neurons. However, sevoflurane additively potentiated the tonic GABA currents in both cells. Interestingly, 4,5,6,7‐tetrahydroisoxazolo[5,4‐c]pyridine‐3‐ol hydrochloride‐sensitive neurons made a large current response to sevoflurane, indicating the contribution of the δ‐subunit on sevoflurane‐enhanced tonic GABA currents. Our findings suggest that sevoflurane can affect the tone of tonic GABA inhibition in a developing striatal neural network.

Discrete subaortic stenosis diagnosed intraoperatively

To the Editor: Discrete subaortic stenosis (DSS) is an uncommon form of left ventricular outflow tract (LVOT) obstruction characterized by a discrete subaortic membrane (DSM) [1]. We report a case of DSS that was misdiagnosed as valvular aortic stenosis (AS) preoperatively with transthoracic echocardiography (TTE) or cardiac catheterization and correctly diagnosed intraoperatively by careful examination with transesophageal echocardiography (TEE). A 5-year-old boy, who had undergone corrective surgery for coarctation complex in the neonatal period, was scheduled to undergo aortic valve replacement or aortic valve plasty for severe AS. The preoperative diagnosis made by TTE and cardiac catheterization was valvular AS with the peak pressure gradient of 92 mmHg resulting from limited opening of the right coronary cusp (RCC) and moderate aortic regurgitation (AR). Our initial findings with intraoperative TEE after induction of anesthesia were the same (Online Resources 1A–D, 2A). By closer observation, however, we noticed that the tip of the RCC opened almost fully (Online Resource 1B). Because it was difficult to identify the morphological structure causing AS because of the rapid movement of the valve structures, we froze the moving image and reviewed it carefully by frame-by-frame advance. By means of this procedure, we could identify a DSM just below the RCC that obstructed the LVOT (Online Resources 3A,B) and thus could establish the diagnosis of DSS. Resection of the DSM was performed on mild hypothermic cardiopulmonary bypass (CPB). After ending CPB, we confirmed that the DSM was successfully resected (Online Resource 4A), the LVOT obstruction was released (Online Resource 4B), and the grade of AR was reduced from moderate to mild (Online Resource 2B). Continuous-wave Doppler recordings showed that the peak flow rate in the aorta decreased from 4.0 m/s before CPB to 2.6 m/s after CPB (Online Resources 5A,B). Our experience indicates that although TEE is superior to TTE in evaluating morphological features of DSS [1], careful examination is required to identify this structure even when using TEE in some patients with DSS.

Modulation of hyperpolarization-activated cation current Ih by volatile anesthetic sevoflurane in the mouse striatum during postnatal development

Volatile anesthetics have been reported to inhibit hyperpolarization-activated cyclic-nucleotide gated channels underlying the hyperpolarization-activated cation current (Ih) that contributes to generation of synchronized oscillatory neural rhythms. Meanwhile, the developmental change of Ih has been speculated to play a pivotal role during maturation. In this study, we examined the effect of the volatile anesthetic sevoflurane, which is widely used in pediatric surgery, on Ih and on functional Ih activation kinetics of cholinergic interneurons in developing striatum. Our analyses showed that the changes in Ih of cholinergic interneurons occurred in conjunction with maturation. Sevoflurane application (1-4%) caused significant inhibition of Ih in a dose-dependent manner, and apparently slowed Ih activation. In current-clamp recordings, sevoflurane significantly decreased spike firing during the rebound activation, which is essential for responses to the sensory inputs from the cortex and thalamus. The sevoflurane-induced inhibition of Ih in striatal cholinergic interneurons may lead to alterations of the acetylcholine-dopamine balance in the neural circuits during the early postnatal period.