Comparison of Mechanical Insufflation-Exsufflation Using a Stand Alone Device and Integrated Into a Ventilator

Background:

MI-E improves secretion clearance in neuromuscular weakness. To date MI-E has required a second, stand-alone device. We compared flows and airway pressures with the T-70 (Philips, Murrysville, PA) and VOCSN (Ventec, Bothell, WA).

Methods:

Each device was connected to an ISO rigid lung model with CLset at 50 or 80 mL/cm H₂O and Raw of 10 cm H₂O/L/s via standard circuits (passive and active). Devices were set at 3 different inspiratory/expiratory pressure settings (+ 30/-30, + 50/+ 50, and + 30/-50 cm H₂O) and 2 inspiratory rise times (fast and slow). Insp and exp times were fixed at 3.0 s with no pause time. Artificial mucus (1 mL) was placed in an 8 mm ID tube over a 2-4 cm distance. Photographs were taken before and after 3 cough cycles and video was recorded for each of 3 trials using a 12 mp camera. Photos were imported to a PC and the distance mucus moved antegrade and retrograde was determined. Net mucus movement was determined as the difference between antegrade and retrograde distance measured at the most proximal and distal edge of the mucus. We measured airway pressures, volumes and flows using a Citrex H5 Analyzer (IMT Analytics, SZ) at 500 Hz and calculated peak PIF and PEF the duration of time PEF is > 90% (T90), IP, EP and delivered V_T. Median and ranges were calculated and compared between the T70 and the VOCSN with a passive (Vp) and active (Va) circuit. Mucus movement was compared using Wilcoxson rank sum test, a P < .05 was significant. Airway pressure and flows were expressed as median (range) and compared using Kruskal-Wallis test. Regression analysis was used to evaluate factors impacting net mucus movement.

Results:

Table 1 displays the data for + 30/-30 at the slow and fast rise time at a CLof 50 mL/cm H₂O. VOCSN resulted in statistically significant (P = .049) increases in mucus movement. Factors impacting mucus movement included PIF, PIF-PEF, and V_T Changes were NSS. Absolute PIF and PEF were higher with T-70 but were not statistically different (P = .121). T90% was longer with VOCSNa, but not statistically significant (P = .121).

Conclusions:

Net artificial mucus movement was greater with VOCSN in 9 of 16 conditions. Our data confirms that faster rise times reduced net mucus movement and that PEF alone is not the primary determinant of MI-E success. Flow and pressure values were comparable between devices. The clinical importance of these findings requires patient testing.

Mucus Movement and Flows, Time

*Comparisons of PIF, PEF,and T90% between devices were not significant by Kruskal-Wallis test p =0.121 # Mucus movement at fast rise time was greater with VOCSNp (p=0.049) compared to T-70

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