We considered the possibility that increases in MIP observed in our training group were produced by familiarization with the test rather than as a result of IMT. Therefore, we recruited a further seven patients who satisfied the entry criteria and measured MIP on two occasions six weeks apart. They had no IMT and no other intervention.
Compliance with Training Program
Nine patients enrolled in the training program. One patient attended training on an infrequent basis (less than two out of three visits) and was withdrawn from the program. The remaining eight patients completed the full number of visits. Patients were not asked to keep records of their training at home, but our impression from the supervised visits was that motivation was high and domestic compliance good.
All results are analyzed by Students f-test and presented as the mean±SD. Baseline pulmonary function data on eight trainees and seven control patients are presented in Table 1. There was no significant difference between the two groups.
The FEVj and VC did not significantly alter over the training period in either the IMT or control group (Table 2). fully
There was no significant change in maximum ventilation (Ve max), oxygen uptake (Vo2 max) or workload (Wcmax) during incremental cycle exercise and no significant change in 12 MWD or MSBC (Table 3). No patient reached 100 percent of predicted maximum heart rate; two reached 90 percent, and the other six attained less than 80 percent of predicted maximum rate. They did not appear limited by cardiac factors.
Measurements during Threshold Breathing
Figure 3 shows the relationship of mean inspiratory mouth pressure Pm (cm H20) to plunger mass (g). The regression line for all data before and after training is given by Pm = 0.31 m + 0.6 (r= .997, standard error of estimate SEE = 1.3) and is very close to that obtained under steady state flow conditions using a blower motor (p= .31 m+0.8, r= .999, SEE = 1.2) and to that predicted by physics, p = 0.32 m.
Table 1—Baseline Respiratory Function
|Age, yr||70 ±6||67 + 8|
|FEV„ L||,9± .2||.9 ±.3|
|VC, L||3.7 ±1||3.2 ±.8|
|TLCO, % pred”||54 ±19||53 ±26|
|PaOj, mm Hg||73±8||70 ±8|
|PaCO„ mm Hg||38±4||38±3|
Table 2—Maximal Inspiratory Pressure
|Week 1||Wfeek 6|
|IMT (n = 8)|
|FEV„ L||.9 ±.2||.8+.3|
|MIP-FRC, cm HtO||40 ±19||66 ±27*|
|MIP-RV cm H.O||59 ±27||79±34t|
|Control (n = 7)|
|FEV„ L||.9 ±.3||.9 ±.3|
|VC, L||3.2 ±.8||3.2 ±1|
|MIP-FRC, cm H.O||34 ±16||37 ±17|
|MIP-RV cm HtO||45 ±16||45 ±14|
Table 3—Maximal Ventilation and Exercise
|Before IMT||After IMT|
|Vcmax, L/min||33±9||34 ±10|
|Vo,max, L/min||.8 ±.3||.8 ±.2|
|Wcmax, W||45+16||49 ±12|
|12 MWD, M||908 ±257||905 ±268|
|MSBC, L/min||33 ±10||32 ±9|
Figure 3. Mean mouth pressure determined from planimetry of pressure-volume curves as a function of plunger mass during threshold breathing.
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