[Anesthetic management of an extremely low birth weight neonate for two thoracic surgeries of patent ductus arterious and coarctation of the aorta].

An extremely low birth weight (832 g) and 29 gestational week neonate underwent surgical ligation of patent ductus arterious 20 days after birth and repair of coarctation of the aorta two months after the first operation. She developed asphyxia neonatorum and was artificially ventilated because of IRDS and attack of apnea. At the first operation, anesthesia was maintained with fentanyl and sevoflurane. The only perioperative complication was severe hypothermia (34.5 degrees C). At the second operation, anesthesia maintenance was identical to the first operation. The only perioperative complication was mild hyperthermia (37.7 degrees C). The key points of anesthetic management were the use of a low inspired oxygen fraction to avoid retrolental fibroplasia at a gestational age before 32 weeks and management of the baby's temperature.

[A report on 107 cases of obturator nerve block].

The obturator nerve passes in close proximity to the inferolateral bladder wall. Transurethral resection of bladder tumors close to these areas may stimulate the obturator nerve, causing violent adductor contraction and possible inadvertent bladder perforation. To avoid this reaction, local anesthetic blockade of the obturator nerve as it passes through the obturator canal is effective to stop adductor spasm during spinal anesthesia. We performed obturator nerve block in 107 cases by use of insulated needle and nerve stimulator, and measured the depth of the obturator nerve and that of the pubic tubercle. Obesity index was positively correlated with the depth of the obturator nerve as well as the pubic tubercle. However, no correlation was found between the obesity index and the difference of the depth of the obturator nerve and the depth of the pubic tubercle. It is suggested that if the needle is advanced in the direction of the obturator canal about 40mm further after reaching the pubic tubercle, the needle reaches the obturator nerve.

The separating capacity of a multithreshold threshold element.

In answer to what represents the intrinsic information-processing capability of the pattern classification system, Cover [1] has defined the separating capacity, and has derived it for the linear machine and the so-called ¿ machine. In this paper, the separating capacity of a multithreshold classification element is obtained. It is shown that the capacity of a multithreshold threshold element with k thresholds-k-threshold element-in n-dimensional space is 2(n + k). A linear machine is a special case in the k-threshold element with k = 1; therefore, its capacity becomes 2(n + 1) from the above result. Further, although it is intuitively apparent that the larger the number of thresholds, the more powerful the information-processing capability of the k-threshold element, using the capacity as a measure of this capability, we may now state that the separating power of the k-threshold element increases linearly with respect to k.

Analytical isotachophoresis utilizing computer simulation. II. Assessment of optimum separation conditions for urinary trifluoroacetic acid metabolized from anaesthetic halothane.

Experimentally determined optimum separation conditions for a metabolite of anaesthetic halothane in urine, trifluoroacetic acid, were assessed by means of computer simulation of the isotachophoretic steady-state. The simulation confirmed that urinary acids and trifluoroacetic acid can be separated in the limited pH range of 3.5-3.7 buffered by beta-alanine, as far as the pH dependence of effective mobility is utilized. The separated fraction of the trifluoroacetic acid zone was identified by mass spectrometry. The simulated coefficient of the calibration curve agreed well with the observed value.

Quantitative analysis of trifluoroacetate in the urine and blood by isotachophoresis.

Trifluoroacetate (TFA), the major metabolite of halothane, was assayed by a newly developed isotachophoretic technique. This technique has several advantages over the presently used methods of analysis. It requires no special preparation of urine or blood samples. The sample volume is small (5--100 microliters) and the analysis time is short (30--90 min per sample). In addition, the method provides an analysis that is both qualitative and quantitative over a wide range of concentrations (from 2 nanomoles in 200 microliters to 200 nanomoles in 5 microliters). In this study, the assay was performed using HCl (0.001 M) in 1 per cent Triton X-100, titrated with beta-alanine to a pH value of 3.6--3.9 as the leading electrolyte and n-caproic acid (0.01 M) as the terminal electrolyte (50--100 muA migration current). Using this technique, daily urinary TFA excretion of seven patients was measured during halothane anesthesia and for 14 days postoperatively. The TFA values were highest on the second postoperative day (317--1,259 mg). The mean values of the urinary TFA excreted during the entire study (2,501 +/- 493 mg, mean +/- SEM) were much higher than those reported previously. The isotachophoretic technique provides a sensitive assay for future research into the biotransformation of halothane.