Many acute and chronic respiratory ...

Many acute and chronic respiratory diseases are associated with increased respiratory secretions in the airways. Narrative reviews and a hardly any systematic reviews of secretion clearance techniques have been published. These reviews raise disturbs regarding the lack of evidence to support the various secretion clearance techniques. I convoyed a comprehensive MEDLINE search of the following subjects: chest physical therapy, chest physiotherapy, postural drainage, forced expiratory technique, autogenic drainage, high-frequency chest wall compression, flap device and secretions, positive expiratory constraining force and secretions, intrapulmonary percussion, mechanical in-exsufflation and secretions. This was followed on a comprehensive search of cross-reference to identify additional studies. The follows of this review are reported herein. There are a number of methodological limitations of the literature reporting studies of the use of secretion clearance techniques. principally of the studies were small, principally used crossover designs, and hardly any used sham therapy. Many studies were limited to shortterm issues such as sputum clearance with a single treatment session. Despite clinical observations that retained secretions are detrimental to respiratory function and despite anecdotal associates between secretion clearance and improvements in respiratory function, there is a dearth of high-level evidence to support any secretion clearance technique.

Key words: secretion clearance, respiratory secretions, evidence-based medicine

INTRODUCTION

Healthy lung effectively clear mucus from the airways via the mucociliary escalator. When the mucociliary escalator is challenged (for example, with infection or aspiration), effective secretion clearance is provided by means of the cough reflex. Many acute and chronic respiratory diseases are associated with increased respiratory secretions in the airways suitable to increased mucus production, impaired mucociliary transport, or a weak cough It is generally assumed that retained secretions forward infection, atelectasis, and abnormalities in gas exchange and lung mechanics. All respiratory therapists have had experiences in which secretion clearance improved respiratory mechanics and gas exchange.

In patients with chronic respiratory diseases associated with mucus expectoration (for example, cystic fibrosis, chronic bronchitis, and bronchiectasis), it is unknown whether increased respiratory secretions contribute to the deterioration of respiratory function or whether this is simply a symptom associated with the progression of the disease. Moreover, it should be recognized that increased expectoration of mucus does not imply mucus stasis in the airways of the lung There is a relative lack of evidence describing the power of increased respiratory tract secretions forward the progression of disease, and there is equable less evidence that secretion clearance techniques improve the course of disease. Despite this lack of evidence, as clinicians we are troubl on respiratory secretions and standard practice calls for efforts to clear these from the lung Indeed, an important proportion of respiratory therapists' time is exhausted in efforts to evacuate secretions from the lower respiratory tract. Moreover, in latter years a variety of equipment (of varying cost) has become available to assist with this.

DEFINITION OF TECHNIQUES

Many techniques can be used to improve secretion clearance from the lower respiratory tract (Table 1) Those that are considered in this review are defined below.

Directed cough A technique that mimics the attributes of an effective spontaneous cough; the cough can be manually assisted by dint of application of external pressure to the epigastric region or thoracic cage during the expiratory phase (as in the patient with neuromuscular disease); sometimes called quad coughing.

Forced expiratory tech (FET) Sometimes called fume coughing, this technique consists of single in kind or 2 huffs from mid-to-low lung tomes with the glottis open, followed according to relaxed diaphragmatic breathing.

Chest physiotherapy. (CPT) This technique has traditionally included postural drainage, percussion, and vibration. Postural drainage is a technique in which the patient is positioned to facilitate gravity drainage of secretions from the airways. Percussion is a technique of clapping the chest wall. Vibration applies fine shaking of the chest wall, usually during the expiratory phase. Percussion and vibration can be applied using either manual or mechanical techniques.

Positive expiratory hurry (PEP). With this technique, the patient exhales against a squeezing of 10-20 cm H^sub 2^O

Flutter This technique uses a device that yields PEP with oscillations in the airway during the expiratory phase.

Active period of breathing. This technique includes breathing rule FET, thoracic expansion techniques, and may include CPT

Manual hyperinflation. This is a technique to improve secretion clearance according to use of a manual ventilation device (manual resuscitator). It can be used in conjunction with CPT and manually assisted cough It involves a dead deep inspiration with a manual ventilation device, an end-inspiratory pause, and a fast, unobstructed exhalation.