Pursed-lip sucking in Asthma
Pursed-lip breathing (PLB) results in a positive air pressure which assists keeping the airways open longer such that more carbon dioxide escapes that may be substituted with fresh air. This process of breathing has numerous advantages especially to asthmatics. Some of them are highlighted below:
� Increases the volume of inhaled and exhaled air (vital capacity)
� It helps each of the stale air to escape from lungs.
� It lengthens some time for which the airways remain open and therefore less effort is necessary for breathing.
� It contributes to better alveolar exchange of gases and so more oxygen can enter in the bloodstream and more skin tightening and can exit.
� It relaxes our bodies by enhancing the parasympathetic central nervous system.
In an asthma attack, less air reaches the lungs as the bronchiget inflamed and secrete excess mucus that makes our bodies work harder to breathe.
Pursed-lip breathing makes breathing more potent mainly because it cuts down on the energy for work to breathe by helping the utilisation of the diaphragm and the intercostal muscles instead of chest and neck muscles.
Oxygen Saturation (SO2) means the amount of haemoglobin which is fully combined with oxygen. Oxygen Saturation falls in asthmatic attacks as a result of airway obstruction.
PO2 (Partial Pressure of Oxygen) could be the amount of oxygen contained in the bloodstream. It reflects the efficacy of lungs to get oxygen in to the blood from outside. It falls in asthmatics particularly in attacks.
Inhalation of air can be an active movement concerning the contraction of diaphragm and auxiliary muscles to generate negative pressure which pulls air into the lungs. Exhalation is generally a passive movement since the air flows across the pressure gradient which doesn�t require energy and so no muscular activity should be used. Since inhalation is active and exhalation is passive, respirationinfluences the autonomous nervous system as in inhalation there is an boost in sympathetic activity while during exhalation it has an surge in parasympathetic activity. Thus heart rate increases during inhalation as muscle sympathetic activity is suppressed and decreases during exhalationdue to muscle sympathetic activity.This is whats called respiratory sinus arrhythmia which can be linked to vagal tonus.
PLB induces heart rate changes just like what is affecting respiratory sinus arrhythmia. Many experts have linked to better efficiency in pulmonary gas exchanges, thereby producing better alveolar perfusion and ventilation.