Experimental and clinical tests of the oxyconsumeter: a new oxygen uptake monitor.

The prototype of a microprocessor controlled oxygen uptake monitor oxyconsumeter developed by Draegerwerk AG, Luebeck, FRG, has been tested. The measuring accuracy of this device was assessed with laboratory bench experiments utilizing both the nitrogen dilution technique and the hydrogen combustion technique to simulate oxygen uptake (VO2). The correlation coefficient between the simulated and the measured VO2 values was 0.

The efficiency of various humidifiers for respired gas.

Eight different breathing gas humidifiers were tested by humidity measurements using two independent methods under simulated clinical conditions. The comparison considering the influence of tidal volume and inspiratory/expiratory ratios revealed great differences between the individual devices depending on the kind of humidification and functional principles. Only four of the humidifiers tested: Ultrasonic Nebulizer NB 108, Hydrotrop 200, Bennett Cascade and Nicholas Humidifier, gave a constant performance of more than 30.

[Review of the development of air humidifiers working on the principle of evaporation with reference to their experimentally assured efficacy].

Basing on own measurements of the efficiency of customary water-bath humidifiers (humidifier of the ventilator RO-5 R, humidifier of the ventilator Engström ER 200, Bennett Cascade Humidifier, Hydrotrop 200 and Nicholas Humidifier) a critical review is given. As the results show only 3 of the humidifiers (Bennett Cascade Humidifier, Hydrotrop 200 and Nicholas Humidifer) make sure a really breathing air "conditioning" (moistening and rewarming). The humidifers of the ventilators RO-5 R and Engström ER 200 have only a very low efficiency, therefore they are not suitable for long term ventilation.