Medicine of the Future in America

Effects of Aerosol Ipratropium Bromide on Cardiac Vagal Tone: Asthma Severity

Effects of Aerosol Ipratropium Bromide on Cardiac Vagal Tone: Asthma SeverityAsthma tended to be mild on the day of testing with IB or placebo (Table 1). Of the 12 subjects tested with methacholine, 5 had FEVi reductions of at least 20 percent after one to three doses (severe asthma), 6 after four to six doses (moderate asthma), and 1 after seven doses (mild asthma). The mean tolerance was four methacholine doses.
Airway Response to IB
The MANOVA revealed a significant (p<0.003) interaction between DRUG and PRETEST/POSTTEST, using Wilks’ lambda statistic. This interaction reflected an increase in all measures after IB, but no change after the placebo.
The MANOVA was followed by univariate analyses of variance for each spirometry variable separately. Canadian health & care mall this As can be seen in Tables 2 and 3, subjects improved significantly PRE to POST after IB, relative to placebo, on all three measures of pulmonary function. No significant effects for ORDER were found.
Cardiac Measures
As can be seen in Tables 3 and 4, RSA (cardiac vagal tone) and cardiac interbeat interval (IBI, in milliseconds) tended to increase from presession to postsession in response to the placebo. For IBI, the increase was greater in the second session than in the first, irrespective of drug condition. This is reflected in a significant ORDER X DRUG X PRETEST/ POSTTEST interaction (Table 3), which is computationally equivalent to a SESSION X PRETEST/ POSTTEST interaction. In the placebo condition, all subjects demonstrated increases in RSA between the pretest and posttest periods. An increase in RSA also occurred in the IB condition when it was presented in the second session, but not in the first. However, this result must be treated with caution because the ORDER X DRUG X PRETEST/POSTTEST interaction was not significant.

Table 1—Predrug Percent Expected Spirometry

Measure IB Session Placebo Session
M SD M SD
FEVi 72.3 20.8 69.3 22.0
FEF50% 49.4 32.1 46.0 32.0

Table 2—Effects of Ipratropium Bromide on Spirometric Variables

SpirometryVariable N Ipratropium bromide Placebo
Pre Post Pre Post
M SD M SD M SD M SD
FEVi 31 2.43 0.78 2.59 0.86 2.31 0.82 2.33 0.78
FEF50% 30 2.54 1.63 2.99 1.75 2.31 0.82 2.30 1.53
FEVi/FVC 30 70.7 12.9 73.4 13.4 69.1 13.7 69.1 13.1

Table 3—Analysis of Variance Summary

Measure Pre/Post Effect t DrugXPre/Post Order X Drug X Pre / Post | (Session X Pre/Post)
F (df) P F (df) P F (df) P
FEVi 13.10 (1,29) <0.002 4.39 (1,29) <0.05 0.05 (1,29) NS
FEF50% 6.26 (1,28) <0.02 18.79 (1,28) <0.001 0.27 (1,28) NS
FEVi/FVC 6.64 (1,28) <0.02 5.15 (1,28) <0.04 0.01 (1,28) NS
V 11.35 (1,29) <0.003 2.19 (1,28) NS 2.99 (1,28) <0.1
IBI 25.74 (1,29) <0.001 4.02 (1,28) <0.06 10.45 (1,29) <0.004

Table 4—Effects of Ipratropium Bromide on Vagal Tone (V) and Cardiac Interbeat Interval (IBI)

Measure IB/PlaceboOrder* N Ipratropium Bromide Placebo
Pre Post Pre Post
M SD M SD M SD M SD
Vf IB first 19 6.00 1.46 5.80 1.34 5.75 1.94 6.26 1.67
IB second 12 6.13 0.91 6.76 1.06 5.99 0.67 6.57 0.81
I Bit IB first 19 777.7 128.8 809.0 130.0 772.9 106.6 827.4 132.6
IB second 12 819.3 125.6 894.9 141.8 814.1 119.8 840.3 120.8
This entry was posted in Pulmonary function and tagged asthma, cardiac vagal, cardiac vagal tone, heart rate, ipratropium bromide, methacholine challenge tests.
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