Hong-Lin Du

Efficiency of a New Fiberoptic Stylet Scope in Tracheal Intubation

BACKGROUND Failed or difficult tracheal intubation is an important cause of morbidity and mortality during anesthesia. Although a number of fiberoptic devices are available to circumvent this problem, many do not allow manual control of the flexion of the tip and necessitate time-consuming preparation, special training, or the use of an external light source. To improve these limitations, the authors designed a new fiberoptic stylet scope (FSS) that has a simple form of a standard stylet with the fiberoptic view and maneuverability of its tip. This study was undertaken to prospectively evaluate the effectiveness of the FSS in tracheal intubation. METHODS Thirty-two patients undergoing general surgery participated in this study. The authors used a standard laryngoscope only to elevate the tongue, then tracheal intubation was attempted with the glottic opening being viewed only through the FSS. The success rate, time necessary for intubation, hemodynamics, and adverse effects were recorded. RESULTS The success rate of tracheal intubation on the first attempt using the FSS was 94% (30 of 32 patients), and the remaining two patients were intubated successfully on the second attempt. The mean time necessary for the intubation procedure was 29+/-14 s in all patients (mean +/- SD). Changes in hemodynamics during intubation were well within acceptable ranges. There were no major adverse effects, but minor sore throat (28%) and minor hoarseness (25%) on the first postoperative day. CONCLUSIONS Tracheal intubation using the FSS proved to be a simple and effective technique for airway management.

Automation of expiratory trigger sensitivity in pressure support ventilation.

Patients under pressure support ventilation sometimes encounter patient-ventilator asynchrony in the transition from inspiration to expiration, that is, expiratory asynchrony. This problem is caused by the incompatibility of the fixed level of expiratory trigger sensitivity termination criteria (i.e., flow termination criteria) in the ICU ventilators to various patient conditions. The user-adjustable expiratory trigger sensitivity implemented in some newly released ventilators has been experienced to be difficult to use and unable to adapt ever-changing patient conditions without user intervention, although it provides more flexibility. This article elucidates the rationale for automatic control of the expiratory trigger sensitivity and evaluates the automation system with a bench setup. The evaluation data suggest that good expiratory synchronies can be achieved through automatic adjustments of expiratory trigger sensitivity.

Beneficial effects of the prone position on the incidence of barotrauma in oleic acid‐induced lung injury under continuous positive pressure ventilation

Background: Factors that contribute to ventilator‐induced barotrauma are not well defined. This study investigates the effects of posture on ventilator‐induced barotrauma, as well as arterial oxygenation.

Vagal and sympathetic denervation in the development of oleic acid-induced pulmonary edema

This study investigates the effects of autonomic denervation on extravascular lung water, pulmonary hemodynamics, the filtration coefficient of pulmonary vasculature and oxygenation in the development of pulmonary edema. Thirty seven dogs were divided into seven groups. No experimental treatment was conducted in group Nc (n = 4, sham operation) or group Nv (n = 6, bilateral vagotomy) during a 3 h observation period. In the following groups, oleic acid (0.06 ml/kg) was injected into a central vein to induce pulmonary edema: group OAc (n = 6, intact innervation); group OAv (n = 6, bilateral vagotomy); group OAa (n = 6, alpha-blockade by phentolamine); group OAs (n = 6, alpha- and beta-blockade by sympathectomy); and group OAvs (n = 3, vagosympathectomy). The results showed that in the dogs with normal lungs, bilateral vagotomy per se did not cause lung injury during 3 h of observation. However, in oleic acid pulmonary edema, vagotomy significantly deteriorated pulmonary edema by increasing pulmonary intravascular pressures; Alpha- or alpha- and beta- sympathetic inhibition deteriorated pulmonary edema by increasing pulmonary microvascular permeability. The severity of oleic acid-induced pulmonary edema was same in the dogs with vagosympathectomy as in the dogs with intact innervation. These results suggest the inhibition of vagal or sympathetic innervation will aggravate pulmonary edema in the dog.

Postoperative left recurrent laryngeal nerve palsy possibly caused by coincidental swelling of the metastatic mediastinal lymph node

1 Surgical Center, The Institute of Medical Science, University of Tokyo, 4-6-1 Shirokane-dai, Minato-ku, Tokyo 108-8639, Japan 2 Department of Surgery, The Institute of Medical Science, University of Tokyo, Tokyo, Japan 3 Department of Radiology, The Institute of Medical Science, University of Tokyo, Tokyo, Japan 4 Department of Anesthesiology, Faculty of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan

Estimation of cerebrospinal fluid pressure via lumbar epidural space by equilibration method

By introducing water into the lumbar epidural space from a vertically held tube under gravity, we measured lumbar epidural pressure (EDP) when the water meniscus no longer declined. In principle, the pressure of either side of dura mater had become equal at this time which is referred to as the equilibrium point. EDP measured in this way was consistently 1–3 mmHg lower than lumbar cerebrospinal fluid pressure (CSFP) not only immediately after the equilibrium point, but also for 5 min after the equilibrium point had been reached. Both EDP and CSFP responded sensitively to the manipulations of CSFP during this period. We suggest that this method may provide a means to continuously monitor CSFP by EDP.

Intraperitoneum insufflation of carbon dioxide increases epidural pressure in laparoscopic cholecystectomy.

Laparoscopic cholecystectomy is being performed with increasing frequency because of its low level of postoperative pain, faster recovery, and shorter hospitalization [1], but data recorded during this procedure indicate that it affects some physiologic functions. For example, intraperitoneum insufflation with carbon dioxide (CO2) often has a depressive effect on circulation and respiration [2, 3]. However, little is known about the effect of CO2 pneumoperitoneum on intracranial pressure or cerebrospinal fuid pressure, partly because of the difficulty in measuring these parameters. In this study, we continuously measured epidural pressure after injecting a known volume of local anesthetic at a fixed speed. We used epidural pressure as an indirect measure of cerebrospinal fluid pressure when it was relatively stable after epidural injection [4-6]. The influence of CO2 pneumoperitoneum on epidural pressure in laparoscopic cholecystectomy was evaluated.