Mechanism of spirometry associated gastro-esophageal reflux in individuals undergoing esophageal assessment

Persistent variability observed during spirometry, even when technical and personal factors are controlled, has prompted interest in uncovering its underlying mechanisms. Notably, our prior investigations have unveiled that spirometry has the potential to trigger gastro-esophageal reflux in a susceptible population. This current study embarks on elucidating the intricate mechanisms orchestrating reflux induced by spirometry. To achieve this, we enlisted twenty-four (24) participants exhibiting reflux symptoms for esophageal assessment. These participants underwent two sets of spirometry sessions, interspersed with a 10-minute intermission, during which we closely scrutinized fluid flow dynamics and esophageal function through high-resolution impedance esophageal manometry. Our comprehensive evaluation juxtaposed baseline manometric parameters against their equivalents during the initial spirometry session, the intervening rest period, and the subsequent spirometry session. Remarkably, impedance values, serving as a metric for fluid quantity, exhibited a substantial elevation during each spirometry session and the ensuing recovery interval in the pan-esophageal and hypopharyngeal regions when compared to baseline levels. Additionally, the resting pressure of the lower esophageal sphincter experienced a noteworthy reduction subsequent to the first bout of spirometry (13.6 ± 8.8 mmHg) in comparison to the baseline pressure (22.5 ± 13.3 mmHg). Furthermore, our observations unveiled a decline in spirometric parameters-FEV1 (0.14 ± 0.24 L, P = 0.042) and PEFR (0.67 L/s, P = 0.34)-during the second spirometry session when contrasted with the first session. Collectively, our study underscores the compelling evidence that spirometry maneuvers can elicit gastro-esophageal reflux by eliciting intra-esophageal pressure differentials and inducing temporary relaxation of the lower esophageal sphincter.

Somatically evoked cough responses help to identify patients with difficult-to-treat chronic cough: a six-month observational cohort study

BACKGROUND

Recently we identified in patients with chronic cough a sensory dysregulation via which the urge-to-cough (UTC) or coughing are evoked mechanically from "somatic points for cough" (SPCs) in the neck and upper trunk. We investigated the prevalence and the clinical relevance of SPCs in an unselected population of patients with chronic cough.

METHODS

From 2018 to 2021, symptoms of 317 consecutive patients with chronic cough (233 females) were collected on four visits (V1-V4) 2 months apart at the Cough Clinic of the University Hospital in Florence (I). Participants rated the disturbance caused by the cough (0-9 modified Borg Scale). We attempted to evoke coughing and/or UTC using mechanical actions in all participants who were subsequently categorised as responsive (somatic point for cough positive, SPC+) or unresponsive (SPC-) to these actions. An association was established between chronic cough and its commonest causes; treatments were administered accordingly.

FINDINGS

169 patients were SPC+ and had a higher baseline cough score (p < 0.01). In most of the patients, the treatments reduced (p < 0.01) cough-associated symptoms. All patients reported a decrease (p < 0.01) in cough score at V2 (from 5.70 ± 1.4 to 3.43 ± 1.9 and from 5.01 ± 1.5 to 2.74 ± 1.7 for SPC+ and SPC- patients respectively). However, whilst in SPC- patients the cough score continued to decrease indicating virtually complete cough disappearance at V4 (0.97 ± 0.8), in SPC+ patients this variable remained close to V2 values during the entire follow-up.

INTERPRETATION

Our study suggests that the assessment of SPCs may identify patients whose cough is unresponsive and are eligible for specific treatments.

FUNDING

This work was funded by an unrestricted grant from Merck (Italy).

Deep Inspiration-Provoked Cough: A Sign of Cough Reflex Arc Hypersensitivity

Deep inspiration-provoked cough (DIPC) is a form of allotussia. Allotussia is thought to be a manifestation of cough reflex arc hypersensitivity but objective evidence about this is lacking. 36 subjects with chronic cough and 25 healthy subjects underwent mannitol and citric acid cough provocation tests. DIPC was defined as two or more coughs after deep inhalation of an empty mannitol capsule. Citric acid was administered utilizing a dosimetric nebulizer during controlled tidal breathing. Nine subjects demonstrated DIPC, 8/36 subjects with chronic cough and 1/25 healthy subjects (p = 0.048). The concentration of citric acid to provoke five or more coughs (C5) was 23.4 (63.8) mM among subjects with DIPC and 750 (2941) mM among the subjects without it (p = 0.006). The number of deep inspiration-provoked coughs correlated with the citric acid C5 (Rs -0.38, p = 0.002). In conclusion, DIPC, a form of allotussia, is associated with cough reflex arc hypersensitivity.Trial Registration Number.ClinicalTrials.gov database KUH5801136.

Global Physiology and Pathophysiology of Cough: Part 1: Cough Phenomenology - CHEST Guideline and Expert Panel Report

The purpose of this state-of-the-art review is to update the American College of Chest Physicians 2006 guideline on global physiology and pathophysiology of cough. A review of the literature was conducted using PubMed and MEDLINE databases from 1951 to 2019 and using prespecified search terms. We describe the basic phenomenology of cough patterns, behaviors, and morphological features. We update the understanding of mechanical and physiological characteristics of cough, adding a contemporary view of the types of cough and their associated behaviors and sensations. New information about acoustic characteristics is presented, and recent insights into cough triggers and the patient cough hypersensitivity phenotype are explored. Lastly, because the clinical assessment of patients largely focuses on the duration rather than morphological features of cough, we review the morphological features of cough that can be measured in the clinic. This is the first of a two-part update to the American College of Chest Physicians 2006 cough guideline; it provides a more global consideration of cough phenomenology, beyond simply the mechanical aspects of a cough. A greater understanding of the typical features of cough, and their variations, may allow a more informed interpretation of cough measurements and the clinical relevance for patients.

Volume feedback during cough in anesthetized cats, effects of occlusions and modulation summary

The study investigates the effects of 6 occlusion conditions on the mechanically induced cough reflex in 15 anesthetized (pentobarbital) spontaneously breathing cats (14♂, 1♀). Esophageal pressure and integrated EMG activities of inspiratory (I) diaphragm and expiratory (E) abdominal muscles were recorded and analyzed. Occlusions: inspiratory (Io), continual I (cIo), during I and active E (I+Eo) cough phase, during I and then E phase with short releasing of airflow before each phase (I-Eo), and E occlusion (Eo) had little influence on cough number. Only continual E occlusion (cEo) reduced the number of coughs by 19 % (to 81 %, p < 0.05). Cough I esophageal pressure reached higher amplitudes under all conditions, but only Eo caused increased I diaphragm motor drive (p < 0.05). Cough E efforts (abdominal motor drive and E amplitudes of esophageal pressure) increased during Eo, decreased during I+Eo (p  < 0.05), and did not change significantly under other conditions (p > 0.05). All I blocks resulted in prolonged I cough characteristics (p < 0.05) mainly cough I phase (incrementing part of the diaphragm activity). Shorter I phase occurred with cEo (p < 0.05). Cough cycle time and active E phase (from the I maximum to the end of cough E motor drive) prolonged (p < 0.05) during all occlusions (E phase duration statistically non-significantly for I+Eo). Airflow block during cough (occlusions) results in secondary changes in the cough response due to markedly altered function of cough central pattern generator and cough motor pattern produced. Cough compensatory effects during airflow resistances are more favorable compared to occlusions. Volume feedback represents significant factor of cough modulation under various pathological obstruction and/or restriction conditions of the respiratory system.

The demographic and clinical characteristics of an Italian population of adult outpatients with chronic cough

BACKGROUND

Chronic cough is a major health problem worldwide and patients are best managed in specialised tertiary centres. Little information is available on the characteristics of chronic cough patients in several European countries, including Italy.

AIMS

We report on the demographic, anthropometric and clinical features of a large Italian population of adult chronic cough outpatients (about 1200), who were referred to a specialised clinic in Florence, Italy, from 2008 to 2018.

METHODS

Demographic, environmental, lifestyle and clinical information was collected at enrolment by means of a custom-designed electronic questionnaire that only allowed for uniform responses. A subjective measure of cough-related discomfort (cough score) was also obtained using a modified Borg Scale. A multivariable logistic regression model was defined to identify the patients' characteristics associated with the cough score.

RESULTS

The characteristics of the examined population (n = 1204 outpatients) were strikingly similar to those described elsewhere. Female patients outnumbered the males [n = 847 females, (70.0%)]; both females and males displayed the same average cough score. The median age of outpatients was 61 (quartile 1 = 48; quartile 3 = 70) years; age and cough duration were unrelated to the cough score. Nasal obstruction, coughing during consultation, coughing during meals, throat clearing and the presence of respiratory abnormalities were correlated with the degree of discomfort caused by coughing.

DISCUSSION

The features of chronic cough patients are similar worldwide. The process of cough reflex hypersensitisation may soothe sex-related perceptual differences, leading to similar levels of discomfort.

CONCLUSIONS

There seem to be clinical indicators that help in assessing the level of cough-related discomfort.

Prevalence and effects of gastro-oesophageal reflux during spirometry in subjects undergoing reflux assessment

Variability during spirometry can persist despite control of technical and personal factors. We postulate spirometry induces gastro-oesophageal reflux (GOR), which may cause variability and affect results of spirometry. Fifty-eight (58) subjects undergoing GOR investigation with oesophageal manometry and 24hr pH monitoring were recruited. Oesophageal dysmotility and GOR were assessed as part of clinical care. Subjects performed 2 sets of spirometry separated by a 10-minute rest period. The assessment of GOR during spirometry procedure (defined by a lower oesophageal pH<4) started from the first set of spirometry and concluded when the second set of spirometry was completed. We calculated variability (%) of FEV₁, FVC and PEFR within each set as well as changes over 10-minutes. Twenty-six subjects (45%) recorded GOR during assessment. Of these, 23 subjects recorded GOR during the 10-minute rest period. Four subjects had GOR recorded only during spirometry tests. We did not find variability of spirometry parameters between the groups with and without GOR during spirometry procedure. However, in subjects with GOR, we found small but significant reductions of PEFR (0.5L/s, 8%, p<0.001) and FEV₁ (84 mL, 3%, p = 0.048) in the second set of spirometry compared to the first spirometry set. This pilot study demonstrates that GOR can occur during and following spirometry. Presence of GOR during spirometry in this patient population caused small decreases in PEFR and FEV₁ when it is repeated 10-minutes later however not increase variability in a single series of measurements.

The Clinical Value of Deflation Cough in Chronic Coughers With Reflux Symptoms

BACKGROUND

Patients with deflation cough (DC), the cough-like expulsive effort(s) evoked by maximal lung emptying during a slow vital capacity maneuver, also present symptoms of gastroesophageal reflux. DC can be inhibited by prior intake of antacids. We wished to assess DC prevalence and association between DC and chemical characteristics of refluxate in patients with gastroesophageal reflux symptoms.

METHODS

A total of 157 consecutive outpatients underwent DC assessment and 24-h multichannel intraluminal impedance pH (MII-pH) monitoring; 93/157 also had chronic cough. Patients performed two to four slow vital capacity maneuvers and DC was detected aurally. Subsequently, they underwent 24-h MII-pH monitoring, the outcomes of which were defined as abnormal when acid or non-acid reflux events were > 73.

RESULTS

DC occurred in 46/157 patients, 18 of whom had abnormal MII-pH outcomes; 28 of the remaining 111 patients without DC also had abnormal MII-pH findings. Thus, in the patients as a group, there was no association between DC and MII-pH outcomes. DC occurred in 40/93 of the chronic coughers; 15 of whom had acid reflux. All but 2 of the 53 patients without DC had normal MII-pH outcomes (P < .001), and the negative predictive value of DC for excluding acid reflux was 96.2%. At follow-up, 65% of coughers showed significant improvement after treatment.

CONCLUSIONS

The overall prevalence of DC was 29%, increasing to 43% in chronic coughers in whom the absence of DC virtually excludes acid reflux. Therefore, DC assessment may represent a useful screening test for excluding acid reflux in chronic coughers with reflux symptoms.

John Widdicombe's contribution to respiratory physiology and cough: reminiscences

John Widdicombe has made substantial contributions to respiratory physiology and to the field of cough particularly. He was one of the first to characterise Aδ-myelinated fibres in the airways that could mediate cough and increased breathing. Later on, he initiated the series of international London Cough Symposia that gathered researchers and clinicians on a two-yearly basis to discuss recent results and concepts regarding cough. John Widdicombe was interested in all aspects of cough from the definition to potential new antitussives. This article will focus on his contributions and on his generous personality through reminiscences from three friends.

The Fontana paradoxical reflex?

This commentary describes the "deflation cough" caused by deep lung deflations. Deflation cough is a paradoxical reflex similar to that described by Henry Head in 1889 for lung inflations that probably is mediated by the same sensors and afferent fibers in the lungs and activated by gastroesophageal reflux. We discuss how this reflex must be self-limiting, the general role of paradoxical reflexes in the body, and the possible clinical significance of deflation cough.

Workshop: tuning the 'cough center'

The Workshop considered the mechanisms whereby the 'cough center' could be tuned by various afferent inputs. There were particular presentations on the effects of inputs from the nose, mouth, respiratory tract and lungs, cerebral cortex, somatic tissues and the pharynx. From all these sites cough induced from the lungs could be increased or decreased in its strength or modified in its pattern. Thus 'tuning' of cough could be due to the interaction of afferent inputs, or to the sensitization or desensitization of brainstem neural pathways. The pattern of response depended on the 'type' of cough being studied and, in some instances, on the timing of the sensory input into the brainstem. Cough inputs could also affect various 'non-cough' motor outputs from the brain, although this was not the main theme of the Workshop. The main conclusion was that cough is not a stereotyped output from the medullary 'cough center', but that its pattern and strength depend on many afferent inputs acting on the 'cough center'.