A newly developed tool for intra-tracheal temperature and humidity assessment in laryngectomized individuals: the Airway Climate Explorer (ACE)

Abstract

The aim of this study is to develop a postlaryngectomy airway climate explorer (ACE) for assessment of intratracheal temperature and humidity and of influence of heat and moisture exchangers (HMEs). Engineering goals were within-device condensation prevention and fast response time characteristics. The ACE consists of a small diameter, heated air-sampling catheter connected to a heated sensor house, containing a humidity sensor. Air is sucked through the catheter by a controlled-flow pump. Validation was performed in a climate chamber using a calibrated reference sensor and in a two-flow system. Additionally, the analyser was tested in vivo. Over the clinically relevant range of humidity values (5-42 mg H 2 O/l air) the sensor output highly correlates with the reference sensor readings (R 2 > 0.99). The 1-1/e response times are all <0.5 s. A first in vivo pilot measurement was successful. The newly developed, verified, fastresponding ACE is suitable for postlaryngectomy airway climate assessment.

A Novel, Simplified Ex Vivo Method for Measuring Water Exchange Performance of Heat and Moisture Exchangers for Tracheostomy Application

“…6) decays exponentially, similar to previously described in vivo AH insp measurements. 6,13,15 Weight change (see Fig. 5) increases linearly for small volumes and then levels off.…”

“…In such measurements extreme care is required to avoid loss of water vapor due to condensation in the sampling tube. 12,13 No commercial equipment is available for these challenging measurements, and experience has shown that custom-built equipment is difficult to develop and maintain. 12,13 Moreover, only a minority of available HMEs thus far have been analyzed both in vitro and in vivo.…”

“…12,13 No commercial equipment is available for these challenging measurements, and experience has shown that custom-built equipment is difficult to develop and maintain. 12,13 Moreover, only a minority of available HMEs thus far have been analyzed both in vitro and in vivo. [12][13][14][15] Therefore, an easy method for assessing HME performance using commercially available equipment could be very useful for medical professionals.…”

“…12,13 Moreover, only a minority of available HMEs thus far have been analyzed both in vitro and in vivo. [12][13][14][15] Therefore, an easy method for assessing HME performance using commercially available equipment could be very useful for medical professionals. Also, for HME development a universally available tool is required for comparing newly designed and existing HMEs next to clinical feasibility studies.…”

“…Inaccuracy of the AH after this calibration is Ͻ 5%. 5,13 At the far end of the T-tube an HME was connected. The dead space of the T-tube is 30 mL, and the dead space of the spirometer flowhead is 70 mL, according to the manufacturer's manual.…”