Purpose
Tracheostomy patients face many adversities including loss of phonation and essential airway functions including air filtering, warming, and humidification. Heat and moisture exchangers (HMEs) facilitate humidification and filtering of inspired air. The Shikani HME (S-HME) is a novel turbulent airflow HME that may be used in-line with the Shikani Speaking Valve (SSV), allowing for uniquely preserved phonation during humidification. The aims of this study were to (a) compare the airflow resistance (
R
airflow
) and humidification efficiency of the S-HME and the Mallinckrodt Tracheolife II tracheostomy HME (M-HME) when dry (time zero) and wet (after 24 hr) and (b) determine if in-line application of the S-HME with a tracheostomy speaking valve significantly increases
R
airflow
over a tracheostomy speaking valve alone (whether SSV or Passy Muir Valve [PMV]).
Method
A prospective observational ex vivo study was conducted using a pneumotachometer lung simulation unit to measure airflow (
Q
) amplitude and
R
airflow
, as indicated by a pressure drop (
P
Drop
) across the device (S-HME, M-HME, SSV + S-HME, and PMV). Additionally,
P
Drop
was studied for the S-HME and M-HME when dry at time zero (T
0
) and after 24 hr of moisture testing (T
24
) at
Q
of 0.5, 1, and 1.5 L/s.
Results
R
airflow
was significantly less for the S-HME than M-HME (T
0
and T
24
).
R
airflow
of the SSV + S-HME in series did not significant increase
R
airflow
over the SSV or PMV alone. Moisture loss efficiency trended toward greater efficiency for the S-HME; however, the difference was not statistically significant.
Conclusions
The turbulent flow S-HME provides heat and moisture exchange with similar or greater efficacy than the widely used laminar airflow M-HME, but with significantly lower resistance. The S-HME also allows the innovative advantage of in-line use with the SSV, hence allowing concurrent humidification and phonation during application, without having to manipulate either device.
Efficient algorithms for construction of recurrence relations for the expansion and connection coefficients in series of quantum classical orthogonal polynomials
