Hyperventilation and asymptomatic chronic asthma

Abstract

Background-We have consistently argued that mild asthma is an important underlying aetiological factor in patients with severe symptomatic hyperventilation. While hyperventilation has been demonstrated in acute asthma, there have been few studies in mild chronic asthma, and mechanisms are uncertain. Methods-Twenty Conclusion-Mild asymptomatic asthmais not associated with clinically significant hyperventilation but is associated with a significant reduction in both arterial and end tidal PCO 2 which relates to airway hyperresponsiveness rather than to the degree of airway obstruction or mucosal inflammation. Anxiety and depression appear not to be implicated.

Targeting pCO2 in Asthma: Pilot Evaluation of a Capnometry-Assisted Breathing Training

“…Thus, improvement through training extended beyond patients' perception of their disease to a somatic outcome measure central to the pathophysiology of asthma. Although the relationship between PEF variability and airway hyperresponsiveness has been debated (Douma, Kerstjens, Roos, et al, 2000;Reddel, Salome, Peat, et al, 1995), such findings are compatible with prior findings of a negative correlation between pCO 2 and hyperresponsiveness to methacholine challenge (Osborne et al, 2000). It is likely that additional benefits of an adjunctive breathing training will be less apparent in basal lung function (or only be visible in more direct measures of airway obstruction) than in a reduction of fluctuations in symptoms.…”

“…On average, initial lung function was close to 100% of predicted, and bronchodilator medication use The range of applicability of hypoventilation training for asthma patients remains to be determined. Although excessive minute ventilation and low pCO 2 are often reported in asthma (Osborne, O'Connor, Lewis, et al 2000;Ritz, Dahme, & Wagner, 1998;Varray & Prefaut, 1992, Kelsen, Fleegler, & Altose, 1979, a sizable number of patients show normal or close to normal levels of pCO 2 . The target for such patients can be stabilization of normal levels of pCO 2 by more regular breathing.…”

“…Experimental studies have demonstrated a decline in lung function when carbon dioxide partial pressure (pCO 2 ) is reduced (Newhouse, Becklake, Macklem, et al, 1964;van den Elshout, van Herwaarden, & Folgering, 1991;Sterling, 1968). Also, lower PCO2 Biofeedback in Asthma 5 pCO 2 levels have been linked to airway hyperresponsiveness in asymptomatic asthma patients (Osborne, O'Connor, Lewis, et al, 2000). Excessive ventilation without hypocapnia is a key mechanism in the development of bronchospasm in asthma and has been suggested to explain exercise-induced bronchoconstriction (McFadden & Gilbert, 1994).…”

“…While oxygen saturation is usaully normal in asthma patients except for periods of severe exacerbation (Wagner, Hedenstierna, & Rodriguez-Roisin, 1996)), studies have found lower resting pCO 2 in patients than in healthy controls (Hombrey et al, 1988;Osborne, O'Connor, Lewis, et al 2000;Ritz, Wilhelm, Meuret, & Roth, 2003) or stronger minute ventilation or respiratory drive at baseline or in response to exercise (Ritz, Dahme, Wagner, 1998;Varray, Prefaut, 1992), added resistive loads (Kelsen, Fleegler, & Altose, 1979), or methacholine-induced bronchoconstriction (Fujimori et al, 1996).…”

Dysfunctional breathing: a review of the literature and proposal for classification

“…Other suggested methods of diagnosis include other questionnaires such as the Self Evaluation of Breathing Questionnaire (SEBQ), end-tidal carbon dioxide measurement (measured using capnography with an expected low end-tidal carbon dioxide in hyperventilation), breath holding time (where a short breath holding time after normal expiration at functional residual capacity is considered an indicator of dysfunctional breathing) and manual assessment of respiratory motion (MARM) [27][28][29][30]. It is important to note that, other than MARM and the Nijmegen questionnaire (which correlate weakly), these methods have yet to been shown to correlate with one another [31].…”