Influence of Morphometry and Airway Patency on Response to Inhaled Methacholine

Figures & data

TABLE 1 Subject demographics and response to methacholine challenge

					6			9
					FEV1	7	8	FEV1	10
1		3	4	5	control	Max	Max FEV1	after	Responsive (R);
Subject	2	Age	Height	Weight	value	challenge	decrease	albuterol	nonresponsive
no.	Gender	(years)	(cm)	(kg)	(L)	(mg/mL)	(%)	(L)	(N-R)
1	F	40	163.0	120.9	2.60	0.025	6.7	2.60	R
2	M	39	183.5	86.4	3.98	0.25	18.8	3.56	R
3	M	27	175.8	91.3	4.00	2.5	12.5	3.88	R
4	F	31	166.8	85.6	3.59	25	9.5	3.64	R
5	F	37	165.0	99.2	2.89	25	6.9	3.09	R
6	F	29	160.0	65.7	3.02	25	6.6	2.97	R
7	M	38	175.9	87.3	3.71	25	6.7	3.62	R
8	F	27	154.0	59.3	2.89	25	4.7	2.93	R
9	M	28	186.4	114.8	4.81	25	2.7	4.71	N-R
10	F	35	165.8	81.1	3.41	25	1.0	3.15	N-R
11	M	40	167.6	100.9	2.80	25	0.0	2.84	N-R
12	M	41	176.6	86.4	4.17	25	0.1	4.38	N-R
13	F	38	154.0	63.9	2.61	25	0.0	2.65	N-R
14	F	36	160.8	81.0	3.02	25	2.5	3.05	N-R

TABLE 2 Individual airway surface area, πLd, and volume factor, Ld ² (mean ± standard error), as a function of airway generation. Measurements from the HRCT scan taken just prior to the methacholine challenge

	Responsive group (n = 8)		Nonresponsive group (n = 6)
	Surface area πLd	Volume factor Ld ^2	Surface area πLd	Volume factor Ld ^2
Airway generation	(cm^2)	(cm^3)	(cm^2)	(cm^3)
1	47.66 ± 3.63	24.0 ± 3.5	46.09 ± 5.84	23.2 ± 5.1
2	13.40 ± 1.34	4.9 ± 0.8	13.23 ± 1.37	4.5 ± 0.7
3	3.58 ± 0.25	0.84 ± 0.10	4.04 ± 0.30	0.97 ± 0.11
4	2.02 ± 0.17	0.38 ± 0.05	2.18 ± 0.19	0.41 ± 0.05
5*	0.86 ± 0.09	0.098 ± 0.016	1.05 ± 0.07	0.138 ± 0.02
6	0.45 ± 0.03	0.035 ± 0.003	0.51 ± 0.03	0.041 ± 0.005
*Volume factors statistically significantly different ( p < 0.05) using the two-tailed t-test; not statistically significantly different using the Wilcoxon rank-sum test.

FIG. 1 Extracted image of lung airways. This image is from a 27-year-old, healthy, nonsmoking female (height = 154 cm, weight = 59.3 kg). This subject was responsive to the methacholine challenge—with the greatest change in airway patency seen in airway generations 4, 5, and 6.

FIG. 2 Impact of bronchodilation. For each subject, morphometric measurements were made from two HRCT scans. The second HRCT scan (the “Post” scan) was made after the methacholine challenge and following bronchodilation. The first HRCT scan (the “Pre” scan) was made prior to the methacholine challenge. Post/pre airway volume factors (Ld ²; mean ± standard error) are compared: nonresponsive (6 subjects, triangles connected with dotted line); responsive (8 subjects, squares connected with solid lines).