[A Problem with Flow Indicators of Anesthesia Machine].

Some anesthesia machines indicate both analog and digital flow volumes of oxygen, air and nitrous oxide. We have noticed that there are discrepancies in the flows between analog and digital flow indicators of two anesthesia machine models (Dräger ; Fabius GS premium and Fabius Tiro). When oxygen or air flow is low, the analog indicator shows higher flows than the digital indicator. In contrast, when oxygen or air flow is high, the analog indicator shows lower flows than the digital indicator. This discrepancy is comparatively small when total gas flow is within the range of 2-5 l x min(-1). We contacted the manufacturer, which replied that the digital indicator is correct and the analog indicator should be regarded as an adjunctive, in case of a power failure when the digital indicator does not function. But this discrepancy may cause practical problems. When we cannot use a digital indicator and have to perform ventilation using a supporting gas cylinder, we may misjudge the available time for oxygen. In addition, when we use only analog indicator, insufficient volume of oxygen may be delivered, leading to the grave hypoxia.

[Anesthetic management of a patient with aortocaval fistula caused by rupture of a huge abdominal aortic aneurysm into the inferior vena cava].

Aortocaval fistula is a rare complication of ruptured abdominal aortic aneurysm. We report anesthetic management of a patient with aortocaval fistula caused by rupture of a huge abdominal aortic aneurysm into the inferior vena cava. A 51-year-old man who had complained of low back pain and general fatigue was referred to our hospital because of his liver damage. Aortocaval fistula due to rupture of a huge abdominal aortic aneurysm was diagnosed from physical examination, enhanced computed tomography and color Doppler ultrasonography. Anesthesia was induced with propofol and rocuronium, and was maintained with sevoflurane and remifentanil. After induction of anesthesia, the central venous pressure and cardiac index showed remarkably high values because of arteriovenous shunt. When the aneurysm was incised after the clamping of the abdominal aorta, massive venous bleeding occurred from the fistula and caused severe hypotension. Blood pressure recovered by digital compression of the bleeding point and the use of an autotransfusion device. After the repair of the aortocaval fistula, the hemodynamics became stable. The patient had a high output but a good cardiac function in preoperative examination. Therefore anesthesia was managed successfully without worsening high-output heart failure.

[Tracheal intubation with Pentax AWS Airway Scope after failed fiberoptic intubation and failed insertion of the intubating laryngeal mask airway].

Fiberoptic intubation is the most reliable method in patients with difficult airways, but it may be difficult in patients with restricted neck movement. The intubating laryngeal mask airway facilitates fiberoptic intubation, but its insertion may also be difficult in some circumstances. We experienced a case of successful tracheal intubation using the Pentax-AWS (Airway Scope) after failed fiberoptic intubation and failed insertion of the intubating laryngeal mask. A 74-year-old man who had undergone fixation of the cervical spine required reoperation. The magnetic resonance imaging showed a swelling in the posterior pharyngeal wall and glottic edema. The patient's neck was fixed by a cervical collar. After induction of anesthesia and neuromuscular blockade, fiberoptic intubation was attempted but failed, because it was impossible to advance the tip of the fiberscope beyond the epiglottis which was reclining to the swelling in the pharyngeal wall. Insertion of the laryngeal mask also failed, because the pharyngeal swelling prevented its insertion. Insertion of the Pentax-AWS was unaffected by the swelling and tracheal intubation was successful within 10 sec. We believe that the Pentax-AWS can be useful in the patient with restricted neck movement in whom both fiberoptic intubation and insertion of the laryngeal mask have failed.

[Undetachable connection between a reinforced endotracheal tube and L connector].

We anesthesiologists sometimes encounter a situation where we difficulty detaching an L connector from an endotracheal tube. However, to our knowledge, there is no paper wich describes complete inability of detaching the connector from the tube. A 33-year-old female patient was scheduled for jaw joint arthroplasty and manipulation of synarthrophysis after the previous intermaxillary fixation. After midazolam and fentanyl administration, the trachea was intubated with a reinforced endotracheal tube (Mallinckrodt Inc., St. Louis, USA) through the right nostril with the aid of a bronchofiberscope. When we tried to move the anesthesia machine, we could not detach the L connector from the endotracheal tube by any means. Furthermore, because a slip-joint is glued to a reinforced endotracheal tube, it was impossible to separate them. The patient had locklaw, and therefore to avoid reintubation, we scraped off the surface of the L connector, and the connector was successfully detached. Although slip-joints of tracheal tubes and L connectors are standardized with JIS and ISO, their connection is not necessarity good due to the difference of makers and/or a tolerance of products. We think that Tracheostomy Wedge (Portex Inc., New Hampshire, USA) is useful for detaching the cconnection.