The Science Journal of the American Association for Respiratory Care

2004 OPEN FORUM Abstracts

EVALUATION OF VAPOTHERM™2000I FOR HUMIDIFICATION OF THE NEOPUFF INFANT RESUSCITATOR

Brian K. Walsh, RRT-NPS, RPFT; University of Virginia Pediatric Respiratory Medicine; Charlottesville, Virginia

Background: The Neopuff system is used to deliver controlled pressure and flow for infant ventilation during recessitation. A flow of 5-15 lpm enters a T-piece. One arm of the T-piece is connected to a mask. The other arm has a variable leak that provides and regulates PEEP and can be occluded to provide inflation pressure in the mask. The base control unit contains an adjustable pressure relief valve to limit the mask pressure. This evaluation was performed in order to determine whether the Vapotherm could be used to warm and humidify the Neopuff output without affecting its operation. The Vapotherm delivery tube cannot be passed through the Neopuff, so it must be connected to the patient circuit independently.

Method: The Vapotherm was connected to the patient supply line close to the Neopuff T-piece via a second T-piece. Flow through the Neopuff base unit and the Vapotherm were controlled separately. The total flow through the T-piece was targeted at 15 lpm. The Vapotherm set temperature was 43ºC. Room temperature was 22ºC and relative humidity (RH) was 20%. Temperature and RH were measured in the Neopuff T-piece using a Gibeck sensor system, model 15026, and absolute humidity calculated from standard equations.

Results. The table shows RH and temperature under three conditions:

Flow (lpm) Relative Humidity (%) Temperature (ºC) Absolute Humidity(mg/l)
Neopuff Vapotherm      
15 0 19.6 22.8 4.0
7 8 98.2 32.2 34.0
5 10 99.5 36.4 39.8

Using room air alone the RH was 20%. By using the Vapotherm, the RH was increased close to 100%. The temperature of the delivered gas increased with increasing Vapotherm flow as expected. At 8 lpm through the Vapotherm (= 53% of the total flow) the temperature was 32ºC, and at 10 lpm (=67% of total flow) the temperature was 36ºC. Water content at this temperature was increased more than 9 fold over room air.

To confirm that the additional gas stream did not affect Neopuff function, both outlets of the T-piece were occluded and a manometer used to measure the airway pressure. This reading was found to be identical with the pressure displayed on the Neopuff gauge.

Conclusion. The Neopuff output can be heated and humidified effectively using the Vapotherm, with a high RH attainable at a delivered gas temperature of 36ºC. The Vapotherm flow should be connected directly to the Neopuff circuit close to the T-piece to prevent rainout and preferably provide 2/3 of the total flow. The Neopuff’s peak pressure and PEEP regulator operate normally and are not affected by the Vapotherm extra flow.

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