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Vocal cord dysfunction as demonstrated by impulse oscillometry.

ABSTRACT: BACKGROUND:Vocal cord dysfunction (VCD) is a respiratory disorder characterized by inappropriate vocal cord adduction during inspiration. The diagnosis of VCD is challenging, because expected flow volume loop abnormalities are uncommonly noted, and laryngoscopy must be timed to coincide with symptoms. OBJECTIVE:We wanted to determine the potential role of impulse oscillometry (IOS) in the diagnosis of VCD. METHODS:We conducted an analysis of six patients in which the diagnosis of VCD was being considered as well as seven healthy subjects and five subjects with asthma. All were evaluated with IOS and spirometry, and patients underwent laryngoscopy. Two patients with suspected VCD who did not exhibit symptoms or abnormal pulmonary function at baseline underwent exercise challenge and repeat studies. One patient with suspected VCD underwent an additional irritant challenge. RESULTS:VCD was diagnosed by laryngoscopy in three of the six patients in whom the diagnosis of VCD was entertained. These three patients as a group all exhibited higher amplitude (mean, 9.3 cm H20/L/second) and more variable spikes (SD, 4.8 cm H20/L/second) on IOS impedance during inspiration, whereas the three patients in whom the diagnosis was not confirmed by endoscopy did not show these findings (mean, 2.0 cm H20/L/second; P < .0002; SD, 0.8 cm H20/L/second; P < .0001). This pattern was also not observed in the healthy volunteers (mean ± SD, 1.8 ± 0.7 cm H20/L/second) and patients with asthma at baseline (mean, 4.2 ± 1.2 cm H20/L/second) or after exercise challenge (mean, 1.5 ± 0.5 cm H20/L/second). CONCLUSIONS:These findings support the conclusion that IOS displays a characteristic pattern in patients with VCD and thus may offer a rapid and noninvasive adjunct to the assessment and diagnosis of patients suspected to have this disorder.

SUBMITTER: Komarow HD

PROVIDER: S-EPMC4830384 | biostudies-literature | 2013 Jul-Aug

REPOSITORIES: biostudies-literature

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Vocal cord dysfunction as demonstrated by impulse oscillometry.

Komarow Hirsh D HD Young Michael M Nelson Celeste C Metcalfe Dean D DD

The journal of allergy and clinical immunology. In practice 20130628 4

<h4>Background</h4>Vocal cord dysfunction (VCD) is a respiratory disorder characterized by inappropriate vocal cord adduction during inspiration. The diagnosis of VCD is challenging, because expected flow volume loop abnormalities are uncommonly noted, and laryngoscopy must be timed to coincide with symptoms.<h4>Objective</h4>We wanted to determine the potential role of impulse oscillometry (IOS) in the diagnosis of VCD.<h4>Methods</h4>We conducted an analysis of six patients in which the diagno ...[more]

PMID: 24565544

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Project description:BACKGROUND:We previously showed that the long-acting beta agonist (LABA) salmeterol as inhalation powder or metered-dose inhaler improves lung-function parameters assessed by impulse oscillometry (IOS) in 2- to 5-year-old children with reversible-airway disease within 15 minutes. OBJECTIVE:We studied 12- to 45-year-olds with mild persistent asthma in order to compare the onset and extent of peripheral airway effects following the first dose and after 4 weeks dosing with two inhaled corticosteroid (ICS)/LABA combinations: fluticasone propionate/salmeterol 115/21 and budesonide/formoterol 160/4.5. METHODS:Thirty subjects with mild persistent asthma using only an as-needed short-acting beta-agonist (albuterol) who had at least a 40% change in integrated low-frequency reactance postalbuterol were selected and randomized to receive either fluticasone propionate/salmeterol or budesonide/formoterol (15 subjects each). We collected three to six IOS replicates at baseline, at 5, 20, 40, 60, 120, and 240 minutes postdose at randomization, and after 4 weeks of twice-daily dosing. Blinded investigators calculated IOS frequency-dependent resistance and reactance (R5-R20 and AX), indicative of small-airway dysfunction, and also estimated the peripheral airway resistance (Rp ) and peripheral airway compliance (Cp ), using a respiratory-impedance model. RESULTS:At randomization visits, onset of action was detected as early as 5 minutes (t-test, P < 0.05) after fluticasone propionate/salmeterol by Cp , and within 5 minutes after budesonide/formoterol by R5-R20, AX, Rp , and Cp . However, after 4 weeks of dosing, only Rp was significantly different (from 60 to 120 minutes) after fluticasone propionate/salmeterol, while R5-R20, AX, Rp , and Cp were not significantly different within 240 minutes after budesonide/formoterol. CONCLUSION:These two ICS/LABA combinations initially improved the peripheral airway function of 12- to 45-year-old asthmatics significantly in about 5 minutes or less, as measured by R5-R20, AX, Rp , and/or Cp . After regular dosing for 4 weeks, pre- to postdose differences in these parameters had diminished significantly due to improved predose status of peripheral airways. Single dosing with ICS/LABA combinations in mild persistent asthma improves small-airway function, and the effect is maintained over a 12-hour interval by regular use for 4 weeks.

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Vocal cord dysfunction as demonstrated by impulse oscillometry.

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Vocal cord dysfunction as demonstrated by impulse oscillometry.

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