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Deep inspiration avoidance and methacholine response in normal subjects and patients with asthma.
Chest. 2005 Jan; 127(1):135-42.Chest

Abstract

BACKGROUND

Deep inspiration (DI) avoidance and time intervals between inhalation and measurement of FEV1 may influence methacholine challenges.

OBJECTIVES

(1) To compare the degree of airway response to methacholine when the initial FEV1 measurements are obtained either 30 s or 3 min after inhalation, (2) to evaluate a simplified method to study the influence of DI avoidance before inhalation on the fall in FEV1, and (3) to determine if methacholine has a cumulative effect.

PARTICIPANTS/METHODS

Twenty-five patients with asthma and 21 normal subjects without asthma. Four methacholine inhalation tests (MITs) were performed: two standard tidal-breathing MITs, with the first FEV1 measured 30 s (test A) and 3 min (test B) after the end of inhalation; a single-dose MIT, using the last concentration from test B, with no control of DI and the first FEV1 obtained 3 min after inhalation (test C); and an identical single-dose MIT preceded by 20-min of DI avoidance (test D). We compared the provocative concentration of methacholine causing a 20% fall in FEV1 (PC20) from tests A and B (aim 1), the percentage fall in FEV1 from tests C and D (aim 2), and the percentage fall in FEV1 from tests B and C (aim 3).

RESULTS

Mean PC20 values from tests A and B were 1.5 mg/mL and 1.0 mg/mL (p = 0.002) in patients with asthma, and 69.8 mg/mL and 29.9 mg/mL (p < 0.0001) in control subjects, respectively. The mean falls in FEV1 for tests C and D were 22.0% and 24.5% (p > 0.05) in patients with asthma, and 22.1% and 38.9% (p = 0.0005) in control subjects, respectively. The mean falls in FEV2 for tests B and C were 30.2% and 22.0% (p = 0.01) in patients with asthma, and 27.5% and 22.1% (p > 0.05) in control subjects, respectively.

CONCLUSIONS

In both groups, the longer the time interval between the end of inhalation and the first FEV2 measurement, the greater the fall in FEV2 (lower PC20). DI avoidance before inhalation does not enhance the fall in FEV2 in subjects with asthma, while it does in control subjects. Methacholine has a slight cumulative effect that is significant in patients with asthma (p = 0.007).

Authors+Show Affiliations

Institut de cardiologie et de pneumologie de l'Université Laval, Hôpital Laval, Québec City, QC, Canada.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

15653974

Citation

Simard, Barbara, et al. "Deep Inspiration Avoidance and Methacholine Response in Normal Subjects and Patients With Asthma." Chest, vol. 127, no. 1, 2005, pp. 135-42.
Simard B, Turcotte H, Cockcroft DW, et al. Deep inspiration avoidance and methacholine response in normal subjects and patients with asthma. Chest. 2005;127(1):135-42.
Simard, B., Turcotte, H., Cockcroft, D. W., Davis, B. E., Boulay, M. E., & Boulet, L. P. (2005). Deep inspiration avoidance and methacholine response in normal subjects and patients with asthma. Chest, 127(1), 135-42.
Simard B, et al. Deep Inspiration Avoidance and Methacholine Response in Normal Subjects and Patients With Asthma. Chest. 2005;127(1):135-42. PubMed PMID: 15653974.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Deep inspiration avoidance and methacholine response in normal subjects and patients with asthma. AU - Simard,Barbara, AU - Turcotte,Hélène, AU - Cockcroft,Donald W, AU - Davis,Beth E, AU - Boulay,Marie-Eve, AU - Boulet,Louis-Philippe, PY - 2005/1/18/pubmed PY - 2005/2/23/medline PY - 2005/1/18/entrez SP - 135 EP - 42 JF - Chest JO - Chest VL - 127 IS - 1 N2 - BACKGROUND: Deep inspiration (DI) avoidance and time intervals between inhalation and measurement of FEV1 may influence methacholine challenges. OBJECTIVES: (1) To compare the degree of airway response to methacholine when the initial FEV1 measurements are obtained either 30 s or 3 min after inhalation, (2) to evaluate a simplified method to study the influence of DI avoidance before inhalation on the fall in FEV1, and (3) to determine if methacholine has a cumulative effect. PARTICIPANTS/METHODS: Twenty-five patients with asthma and 21 normal subjects without asthma. Four methacholine inhalation tests (MITs) were performed: two standard tidal-breathing MITs, with the first FEV1 measured 30 s (test A) and 3 min (test B) after the end of inhalation; a single-dose MIT, using the last concentration from test B, with no control of DI and the first FEV1 obtained 3 min after inhalation (test C); and an identical single-dose MIT preceded by 20-min of DI avoidance (test D). We compared the provocative concentration of methacholine causing a 20% fall in FEV1 (PC20) from tests A and B (aim 1), the percentage fall in FEV1 from tests C and D (aim 2), and the percentage fall in FEV1 from tests B and C (aim 3). RESULTS: Mean PC20 values from tests A and B were 1.5 mg/mL and 1.0 mg/mL (p = 0.002) in patients with asthma, and 69.8 mg/mL and 29.9 mg/mL (p < 0.0001) in control subjects, respectively. The mean falls in FEV1 for tests C and D were 22.0% and 24.5% (p > 0.05) in patients with asthma, and 22.1% and 38.9% (p = 0.0005) in control subjects, respectively. The mean falls in FEV2 for tests B and C were 30.2% and 22.0% (p = 0.01) in patients with asthma, and 27.5% and 22.1% (p > 0.05) in control subjects, respectively. CONCLUSIONS: In both groups, the longer the time interval between the end of inhalation and the first FEV2 measurement, the greater the fall in FEV2 (lower PC20). DI avoidance before inhalation does not enhance the fall in FEV2 in subjects with asthma, while it does in control subjects. Methacholine has a slight cumulative effect that is significant in patients with asthma (p = 0.007). SN - 0012-3692 UR - https://www.unboundmedicine.com/medline/citation/15653974/Deep_inspiration_avoidance_and_methacholine_response_in_normal_subjects_and_patients_with_asthma_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0012-3692(15)32383-7 DB - PRIME DP - Unbound Medicine ER -