Summary
Objectives
In laryngopharyngeal reflux (LPR) patients acid reaches laryngopharyngeal area and
stimulates/sensitizes respiratory nerve terminals mediating cough. We addressed several
hypothesis: if stimulation of respiratory nerves is responsible for coughing then
acidic LPR should correlate with coughing and proton pump inhibitor (PPI) treatment
should reduce both LPR and coughing. If sensitization of respiratory nerves is responsible
for coughing then cough sensitivity should correlate with coughing and PPI should
reduce both coughing and cough sensitivity.
Study design/Methods
In this prospective single center study, patients with positive reflux symptom index
(RSI > 13) and/or reflux finding score (RFS > 7) and ≥1 LPR episode/24 hours were
enrolled. We evaluated LPR by dual channel 24-hour pH/impedance. We determined number
of LPR events with pH drop at levels 6.0, 5.5, 5.0, 4.5, and 4.0. Cough reflex sensitivity
was determined as lowest capsaicin concentration causing at least 2/5 coughs (C2/C5)
by single breath capsaicin inhalation challenge. For statistical analysis C2/C5 values
were -log transformed. Troublesome coughing was evaluated on the scale 0-5.
Results
We enrolled 27 LPR patients. The number of LPR events with pH 6.0, 5.5, 5.0, 4.5,
and 4.0 was 14[8-23],4[2-6],1[1-3],1[0-2] and 0[0-1], respectively. There was no correlation
between number of LPR episodes at any pH level and coughing (Pearson range -0.34 to
0.21, P = NS). There was no correlation between cough reflex sensitivity C2/C5 and coughing
(R = -0.29 to 0.34, P = NS). Of patients that completed PPI treatment, 11 had RSI normalized (18.36 ± 2.75
vs. 7 ± 1.35, P < 0.01). There was no change in cough reflex sensitivity in PPI-responders. C2 threshold
was 1.41 ± 0.19 vs. 1.2 ± 0.19 (P = 0.11) before and after PPI.
Conclusions
No correlation between cough sensitivity and coughing and no change in cough sensitivity
despite improvement of coughing by PPI argue that an increased cough reflex sensitivity
is not mechanism of cough in LPR. We identified no simple relationship between LPR
and coughing suggesting that this relationship is more complex.
Key Words
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Article info
Publication history
Published online: April 22, 2023
Accepted:
February 15,
2023
Publication stage
In Press Corrected ProofFootnotes
This study was supported by the grant of Ministry of Health of the Slovak Republic: Development of innovative diagnostic methods for the personalization of treatment of extraesophageal manifestations of gastroesophageal reflux disease 2019/43-UKMT-6.
Identification
Copyright
© 2023 The Voice Foundation. Published by Elsevier Inc. All rights reserved.
