Koh Mizutani

Propofol decreases the clearance of midazolam by inhibiting CYP3A4: an in vivo and in vitro study

To examine the effect of propofol on the pharmacokinetics of midazolam in vivo and to elucidate the mechanism of the pharmacokinetic changes of midazolam by propofol with the use of human liver microsomes and recombinant CYP3A4.

Levobupivacaine – dextran mixture for transversus abdominis plane block and rectus sheath block in patients undergoing laparoscopic colectomy: a randomised controlled trial

We performed a randomised controlled double‐blinded study of patients having laparoscopic colectomy with bilateral transversus abdominis plane block plus rectus sheath block, comparing a control group receiving 80 ml levobupivacaine 0.2% in saline with a dextran group receiving 80 ml levobupivacaine 0.2% in 8% low‐molecular weight dextran. Twenty‐seven patients were studied in each group. The mean (SD) maximum plasma concentration of levobupivacaine in the control group (1410 (322) ng.ml−1) was higher than the dextran group (1141 (287) ng.ml−1; p = 0.004), and was reached more quickly (50.6 (30.2) min vs 73.2 (24.6) min; p = 0.006). The area under the plasma concentration–time curve from 0 min to 240 min in the control group (229,124 (87,254) ng.min.ml−1) was larger than in the dextran group (172,484 (50,502) ng.min.ml−1; p = 0.007). The median (IQR [range]) of the summated numerical pain rating score at rest during the first postoperative 24 h in the control group (16 (9–20 [3–31]) was higher than in the dextran group (8 (2–11 [0–18]); p = 0.0001). In this study, adding dextran to levobupivacaine decreased the risk of levobupivacaine toxicity while providing better analgesia.

Another reason for easier right nasal intubation than for left nasal intubation

We read with great interest the recent study by Boku et al [1], which demonstrates that the intubation time was shorter for patients who were intubated via the right nostril than via the left nostril. We agree with their results. They also proposed some reasons for this. However, they did not take into account the direction and shape of the tracheal tube tip that was advanced from a choana into the glottis before attempting to rotate the tube. Apparently, because the bevel is cut from the left side, a tube that approaches from a right choana slides more easily into the glottis than a tube that approaches from the left (Fig. 1). Although this explanation is not generally considered, to us, it is easily understood intuitively. Koh Mizutani, MD (Assistant Chief) Nobuko Uno, DDS (Staff) Operating Theater, Osaka Rosai Hospital 1179-3 Nagasonecho, Kita-ku, Sakai 591-8025, Japan E-mail address: youshookme40@yahoo.co.jp

A case report of seizure during emergence from general anesthesia after lumbar spinal surgery—common cases can develop potentially life-threatening adverse intracranial events

BackgroundAdverse intracranial events after spinal surgery were related with intracranial hypotension due to surgical injury of dura mater.Case presentationA 72-year-old woman received posterior lumbar interbody fusion under general anesthesia. Immediately after the patient was transitioned to the supine position and muscular relaxants were reversed, she developed generalized seizure. The seizure was immediately suppressed with propofol. Brain computed tomography was unremarkable. Although she returned to the surgical suite, an evident point of dural laceration was not found. The dura was covered with fibrin glue. Magnetic resonance imaging revealed subarachnoid hemorrhage (SAH) on postoperative day 1. By postoperative day 2, the seizure had resolved. The cause of her seizure was suspected to be SAH due to intracranial hypotension. Seizure was masked by ongoing anesthesia and muscle relaxation.ConclusionsAlthough spinal surgeries are common procedure, we must carefully consider its related potentially life-threatening adverse events.

Spontaneous shutoff of desflurane vaporizer

Keywords Vaporizer Desflurane Failure EquipmentTo the Editor:We would like to report the intraoperative failure of adesflurane vaporizer. The incident occurred as a 57-year-old man underwent parathyroid surgery. After inductionand intubation, anesthesia was maintained with 5 %inhaled desflurane, using a Tec 6 Plus vaporizer (GEHealthcare Japan Co., Tokyo, Japan), via a semiclosedcircuit with a 3 l/min fresh gas flow. Approximately 7 mininto the case, the ‘‘no output’’ vaporizer alarm sounded andthe desflurane concentration in the anesthesia circuit beganto fall. We immediately turned off the vaporizer. Afterseveral seconds, the vaporizer automatically reset butwithin several minutes, the ‘‘no output’’ error occurredagain. The surgery was then completed using sevoflurane,without assessing the depth of anesthesia. The patientemerged from anesthesia uneventfully, with no recollectionof the intraoperative events.We purchased the vaporizer 2 months prior to theincident; it was used almost every day for 2 months.Although clinical engineers and anesthesiologists maintainanesthetic machines and circuits, vaporizers are notinspected usually in our operating rooms. According to themanufacturer’s technical department, 10 incidences ofinitial failure have been confirmed in 431 products sincethe vaporizer’s 2011 release in Japan. The vaporizer wasexchanged at no charge following this initial failure.Afterward, the manufacturer reported to us that the failureof an electronic pressure transducer caused this incident.They recommended the immediate use of alternativeanesthetics if the ‘‘no output’’ error recurred.Reports of spontaneous shutoff during surgery of acorrectly mounted desflurane vaporizer have not previouslybeen published [1–3]. Unlike conventional mechanicalvaporizers, the desflurane vaporizer has sophisticatedelectronic components. As a fail-safe, it completely haltsagent output if an electronic failure occurs. Since thewashout for desflurane is more rapid than that for otherinhalation agents, patients emerge from anesthesia soonafter shutoff of the vaporizer. The incidence of initialfailure reported by the manufacturer seems relatively high.This case serves to emphasize the importance of fullyunderstanding the features of equipment that is in frequentuse [4].