Breathlessness in Patients with Chronic Airflow Limitation: Conclusion
It should be emphasized that CPAP levels should be carefully titrated to the individual patient’s subjective response; levels in excess of the inspiratory threshold load will result in further hyperinflation and attendant potentially deleterious mechanical, hemodynamic, and sensory consequences. Theoretically, CPAP could be used as an adjunct to exercise training. By prolonging exercise duration, CPAP may permit some very breathless patients to reach the hitherto unattainable threshold at which physiologic training effects are achieved. The potential utility of CPAP in the rehabilitative setting warrants further investigation.
In summary, while the most obvious mechanical defect in CAL is increased expiratory resistance, the major mechanical consequence is inspiratory muscle loading. Qualitatively, breathlessness in CAL primarily encompasses the perception of inspiratory difficulty and is commonly expressed in terms of heightened inspiratory effort or awareness of unrewarded inspiratory effort in detail ventolin inhaler. Intensity of breathlessness correlates closely with physiologic indices such as Ve/MBC or Pes/Pimax, which ultimately reflect motor output (expressed relative to maximum). In the clinical setting, breathlessness in CAL is encountered under conditions of increased ventilation, impeded inspiratory muscle action, or functional weakness. During exercise, acute DH represents an important source of breathlessness in CAL and variation in its extent contributes to intersubject variability in symptom intensity for a given ventilation. Without a precise understanding of the neurophysiologic basis of breathlessness, management strategies are at present largely confined to interventions aimed at reducing ventilatory demand or improving capacity. Given the relatively fixed pathophysiologic derangements of advanced CAL, modalities such as exercise training and O2 therapy, which can reduce ventilatory demand, in part, by altering the metabolic load, are likely to be more useful in relieving breathlessness. In addition, any measure that will reduce DH, ie, bronchodilators, or counterbalance its negative effects on the inspiratory muscles, ie, CPAP, so as to enhance neuroventilatory coupling would ameliorate breathlessness, at least in the acute setting.
Category: Respiratory Symptoms
Tags: breathlessness, chronic airflow limitation, copd, dynamic compression, dynamic hyperinflation, exercise