Yonosuke Yamasaki

A case of tracheomalacia during isoflurane anesthesia

T racheomalacia is a rare disease. Congenital tracheomalacia manifests itself in infancy and may not resolve as the child grows. Acquired tracheomalacia has been reported sporadically, resulting from trauma (including tracheostomy), tumor, infection, inhalation of chronic irritants, and others (l-5). We present a case of tracheomalacia in a female patient with no respiratory problem. She had difficulty in the expiratory phase of spontaneous respiration during general anesthesia because of an extreme narrowing of the tracheal lumen on each expiration that was confirmed by bronchoscopic study.

Correlation of the Speed of Onset of the Effective Relaxation with Vecuronium 0.15 mg/kg with Body Mass and the Size of the Priming Dose

It is said that priming technique shortens the onset time of relaxation with vecuronium. However, too large of a priming dose will cause some problems such as heavy eye lids, swallowing impairment and respiratory discomfort. So, we tried to find a optimal dose of vecuronium in priming technique.

Density-modulated t's array, a new technique of processed electroencephalogram, for monitoring the effects of midazolam and nitrous oxide during spinal anesthesia

We have investigated the utility of a new electroencephalogram (EEG) processing system, density-modulated ts array (DTA), which we have installed in a laptop personal computer together with density-modulated spectral array (DSA) for clinical monitoring. Ten patients scheduled for orthopedic operations on the lower extremities were anesthetized with 0.5% bupivacaine intrathecally, 50% nitrous oxide in oxygen by mask, and midazolam at a dose of 0.1 mg/kg intravenously. Immediately following the administration of the drugs, the power at the frequencies between 15 and 20 Hz increased. However, the power at these higher frequencies disappeared gradually and the power in the delta band and the smaller one in the alpha band became predominant. This pattern of dominant-band shift on the DSA and DTA was observed in all the patients. In three of the patients, the sedation level remained stable as judged by the absence of body movement, quiet, regular breathing and stable hemodynamics as well as steady EEG frequency distribution throughout the operations. They awoke from anesthesia rapidly on withdrawal of nitrous oxide, with return of the power at the higher frequencies. In the other seven patients, the power at the higher frequencies suddenly reappeared on the DSA and DTA during operation and slight movements of the head and upper limbs were observed with rises in blood pressure and heart rate. In three of these seven patients, the EEG change notably preceded the physiological activities by a few minutes. On the DTA, the occurrence of any significant clinical phenomenon was displayed in a color representing at value greater than ±3. The DTA, testing power changes in the EEG at each 1-Hz interval for significant difference, permits the visual and quantitative assessment of EEG changes.

Natural frequency/damping coefficient relationship of the catheter-manometer system required for high-fidelity measurement of the pulmonary arterial pressure.

Using a digital simulation method, we analyzed the relationship between natural frequency (fn) and damping coefficient (ζ) of the catheter-manometer system required for high-fidelity measurement of the pulmonary arterial pressure. The pulmonary artery pressure waveform was obtained with a catheter-tip transducer and it was fed into a dynamic simulator programmed on a computer. The original waveform and the output of the simulator were compared and judged visually for the fidelity. From this analysis, the combination offn and ζ was obtained and was plotted on afn-ζ diagram. It showed as an area, which was convex on the left side and open on the right side. The left-convex endpoint was located at a damping coefficient of about 0.1. At a lower heart rate, this area was extended to the lower frequency side, while, at a higher heart rate, this area was limited to the higher frequency side. Thefn-ζ diagram was also constructed theoretically by calculating the relations between natural frequencies and damping coefficients of a second order system with the amplitude and phase error tolerance set at +/-5% respectively.

Management of Anesthesia Record Using Hyper-Text System

Transfer and storage of pertinent data from original anesthesia records into a data base on personal computers for future reference involve the difficult problems of who and how to do input chores. The process should be user-friendly, that is, it should be simple enough so that any inexperienced users (residents) can handle it. Also, there should be some safe-guards against inevitable mistyping or misspelling errors on the keyboard. Just as much important is the standardized nomenclature in terms of diagnosis, operative procedure and drugs and so forth, otherwise the data base is of no practical use. Extensive lists of standardized diagnostic, procedural, pharmaceutical terms relevant to each surgical subspecialties have been compiled in our department from our own anesthesia records accumulated during the past 15 years. They have been in use on packaged soft-wares (e.g. DBASE III) as well as on programs of our own compilation in data processing and statistical works. The present work is an additional step in facilitating data-input chores by incorporating our diagnostic/procedural lists to “Hypertext” on Macintosh PC making full use of the device of mouse and minimizing the need for keyboard input. Figure 1 shows the tree structure of Hypertext, and Figure 2 shows examples of the contents of Hypertext cards for otolaryngology displaying anatomical sites of the disease, diagnostic categories, and operative procedures associated respectively.

Intra-Operative EEG Monitoring: Monitoring of Background Rhythm and Paroxysmal Activity

The value of EEG monitoring as noninvasive brain monitoring in patients under anesthesia or in critical conditions is readily conceived but simple observation of running EEG wave patterns tells very little. Detection of abrupt appearances of deviation from the on-going background patterns would certainly be helpful in early recognition of grave changes in cerebral function or metabolism. We have developed a prototype EEG analyzer capable of doing this.

An Assessment of Fequency Characteristics of the Fluid-Filled Catheter-Manometer System

A pulmonary artery pressure waveform observed on the screen is an end-product of the force applied to the tip of the catheter subjected to various distortions as it travels down through the mass of fluid in the lumen with its inherent inertial, frictional and elastic moments. The aim of this study is to construct a system of evaluation of the distortion in the pressure waveforms in terms of amplitude and phase angle. The experimental setup consists of the pressure source (a loudspeaker), measurering chamber (a dome) which is open to the reference transducer and the second transducer through the length of the pulmonary artery catheter. The pressure output of the latter is fed to the personal computer through an AD converter and are plotted against frequency.