Design of a test system for fast time response fibre optic oxygen sensors.

A test system has been developed that can be used to calibrate and determine the time response, linearity and temperature sensitivity of a fibre optic oxygen sensor. The simple system obviates the need for precision gas standards and the requirement to generate a true square wave step response, which is seldom achievable. The sensor is mounted in a small chamber containing air or a known fraction of oxygen.

A real-time algorithm to improve the response time of a clinical multigas analyser.

Objective: An algorithm to improve the response time of a clinical respiratory multigas analyser is presented.

Methods: The algorithm involves the application of a second order differential equation to the analyser gas output signals in real-time. The adjusted analyser output signals are compared with those of a quadrupole respiratory mass spectrometer sampling and analysing simultaneously.

Overfill testing of anaesthetic vaporizers.

We tested six anaesthetic vaporizers with keyed filler adaptors to see if it was possible to overfill them. For those vaporizers which could be overfilled, the maximum level of overfill was determined and the effect of overfilling on the vaporizer output concentration was measured. Three of the vaporizers, the TEC 4, PPV Mk 1 and MIE Vapamasta 5, could be overfilled.

The effect of dyshemoglobins on pulse oximetry: Part I, Theoretical approach and Part II, Experimental results using an in vitro test system.

Pulse oximeters are known to be inaccurate in the presence of elevated concentrations of carboxyhemoglobin and methemoglobin. This paper attempts to alleviate some of the confusion that exists between fractional and functional saturation, and to clarify the comparison of each with SpO2. A series of theoretical relationships between pulse oximeter reading (SpO2) and actual oxygen saturation (both fractional and functional) is derived using simple absorption theory.