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This observational, prospective pediatric human study was performed to determine the agreement between brain tissue oxygenation indices (TOI) measured by near infrared spatially resolved spectroscopy and jugular bulb oxygen saturation values (SjO(2)).Five cardiac patients without neurological impairment who were admitted into the critical care unit after open-heart surgery with jugular bulb venous catheters were enrolled. Their mean age was 8.6 months and mean body weight was 6.7 kg. Simultaneous measurements of brain TOI using NIR0-300 (Hamamatsu Photonics, Hamamatsu City, Japan) and SjO(2) values from blood samples were recorded.The TOI range was 59+/-9% and the SjO(2) range was 58+/-17%. The correlation coefficient R was 0.64 (p=0.11; n=14). Bland-Altman plotting revealed a bias of -3.4%, and precision of 7.2% (n=14). Intra-class correlation reliability analysis showed kappa of 0.55.Statistically, brain TOI was in reasonable agreement with SjO(2) in pediatric patients with normal brain within the measurement range from 50 to 70%.

The KATS catheter (continuous arterial thermodeprivation system catheter) measures the blood flow velocity of the pulmonary artery (PA) by thermodeprivation which enables continuous determination of cardiac output. The accuracy of this system may depend on the degree of uniformity of flow velocity in the PA, because small movements of the catheter within the PA are inevitable with a beating heart. We evaluated the flow velocity profile of the PA in seven anaesthetized open-chest dogs to assess these potential errors. A custom-made stiff catheter, at the tip of which was incorporated the flow velocity sensor of the KATS catheter, was used to penetrate the main PA in the short axis direction (perpendicular to flow direction) or the long axis direction (along flow direction). The stiff catheter was moved in increments of 2.5 mm, and flow velocity was recorded. The wall-to-wall distance of the PA along each direction was divided into five sections (S1 to S5 for the short axis, and L1 to L5 for the long axis). Flow velocity data for each section were averaged and presented as relative values against the control mid-point velocity. Along the short axis, flow velocity was 0.41 ± 0.20 (SD), 1.00 ± 0.10, 1.03 ± 0.10, 1.08 ± 0.13 and 0.49 ± 0.26 from S1 to S5, i.e., lower in S1 and S5 which were close to the vascular walls (P < 0.05) but uniform in other areas. Along the long axis, flow velocity was 0.28 ± 0.28, 0.88 ± 0.09, 0.94 ± 0.08, 1.06 ± 0.25 and 1.28 ± 0.50 from L1 to L5. Thus, flow velocity was lower in L1 which was close to the bifurcation (P < 0.05), slightly higher in L5 close to the pulmonary valve, but uniform in other areas. These results suggest that the profile of blood flow velocity is relatively uniform within the main PA except in areas close to the vessel walls or valve. We conclude that movement of the catheter within the vessel would not substantially influence the accuracy of the KATS catheter system as long as the flow velocity sensor of the catheter stays within the main PA.

We held a computer software contest at 38th Congress of the JSA, held in March, 1991. The aim is to encourage the members of the Society to write softwares and to help distribute them, especially as Freewares. We received 25 entries for the contest; two-thirds of these are for computers of NEC PC9801 series and a third are for Macintosh. We received donations 3 million yen worth of instruments and goods for prizes plus some cash, which as prizes were distributed to those who made entries for the contest. Most of these programs have been registered as freewares at various computer networks, including our Ether-Net, one of the common computer network SIGBBS's among Japanese anesthesiologists.

A modified thermodilution catheter (KATS catheter) capable of monitoring continuous cardiac output by thermodeprivation and preserving its conventional function was devised. The KATS catheter has a thermistor incorporated closer to the tip of the catheter in addition to the usual thermistor used for conventional thermodilution. This additional thermistor is heated by a constant electric current but is capable of measuring its own temperature. The degree of heat deprivation is detected as the cooling of the thermistor, which is proportionally larger with larger blood velocity. Since blood flow is not the only source of heat deprivation, the actual formula was empirically derived by performing in vitro studies. Cardiac output can be determined by assuming the cross sectional area of the pulmonary artery is stationary. Calibration can be derived from a cardiac output measurement by the usual thermodilution method with the same catheter. The KATS catheter readings correlated significantly with conventional thermodilution values and electromagnetic flowmeter readings in anesthetized dogs. Continuous cardiac output measurement by the KATS catheter appears to be a promising technique.

Respiratory monitoring of children during general anaesthesia and critical care is in its early stages. Acquisition of physical information remains of great importance because of the difficulties in obtaining specific and objective data from paediatric patients. Many of the obstacles presented by them, such as small and rapid respiration, lack of patient cooperation, use of an uncuffed tracheal tube and relatively higher airway humidity to keep the small airway patent, have been overcome recently by sophisticated technology based on well known principles and thoughtful use of computers. It is now possible to monitor and apply many pulmonary function tests at the bedside that were once confined to the laboratory.

The safety and efficacy of the jet injector (Sanders) technique for bronchoscopy in children was evaluated in a lung analogue and verified by clinical trial. Although the small internal diameters of paediatric bronchoscopes accommodate lower maximum flows, they also produce higher inflation pressures than adult bronchoscopes. It was found that even the smallest tapered bronchoscope (3 mm distal diameter) can compensate for flow limitations by producing high inflation pressures and can deliver tidal volumes of 6–9 ml kg-1 with a driving pressure of 276 kPa (40 PSI).