Myrna Dolovich

Effect of Continuous Lateral Rotational Therapy on Lung Mucus Transport in Mechanically Ventilated Patients

PURPOSE Continuous lateral rotational therapy (CLRT) <40 degrees is a method of altering the position of the ventilated patient to help clear secretions from the lung. CLRT has not been shown to reduce the incidence of atelectasis or pneumonia but potentially offers a way to maximize positional drainage in these patients without producing adverse effects. Treatment intervention, bracketed by two (nonrotational) control periods. The purpose of this study was to determine if CLRT alters mucus transport in critically ill, intubated patients in the intensive care unit of a teaching hospital. MATERIALS AND METHODS Thirteen critically ill, but stable, mechanically ventilated patients, mean age 74 years, were enrolled. They were placed supine on a Biodyne bed (KCI, San Antonio, Texas) and pressures in the cushions adjusted to patients weight. A radiolabeled aerosol was delivered by bagging for 2 to 3 minutes and repeated measurements of lung radioactivity were obtained by imaging of the thorax over the following 3 hours. A 90-minute period of rotation of the bed, 30 degrees to either side was preceded and followed by two 45-minute control periods during which the patient remained supine and stationary on the bed. Coughs and suctions were recorded and blood gases obtained pre and post study. RESULTS (1) The mucous clearance was slower than that reported in normal subjects and in ambulatory patients with COPD; (2) there was a slight, but not significant, increase in clearance during CLRT; (3) clearance reverted to pre-oscillation levels following therapy. Lack of significant effect may be attributed to too shallow an angle for rotation or too short an intervention period. CONCLUSION Positional drainage effected by short duration CLRT did not appear to stimulate significant mucous removal from the lung in critically ill patients but also did not cause any adverse effects.

Methodologic considerations in mucociliary clearance and lung epithelial absorption measurements

Measurements of mucociliary clearance and lung epithelial permeability are relatively simple to perform, with minimum discomfort to the subjects. Awareness of the factors influencing the outcome of these procedures will help to avoid errors and yield useful information about these two clearance mechanisms from both a physiological and a pathological point of view.

Evaluation of lung epithelial permeability

During the last few years a number of factors affecting the measurement of the rate of absorption of 99mTc-DTPA across the alveolar-capillary membrane have been identified. These have helped to provide insights into the significance of lung epithelial permeability (LEP) measurements and their potential limitations. Pulmonary absorption of 99mTc-DTPA has been studied in a variety of clinical conditions and the results are discussed.

Cystic fibrosis—related inhibition of mucociliaryclearance in vivo in man

Studies were performed to demonstrate possibly cystic fibrosis-related inhibition of mucociliary clearance in man. Topical application of normal serum or of CF serum did not inhibit in vivo nasal MCC. Induction of local inflammation by topical anti-IgE-reduced nasal MCC in CF subjects, but increased MCC in normal individuals. Furthermore, nasal MCC was inhibited in normal patients by CF serum but not normal serum, applied to the anti-IgE-treated nasal mucosa. These observations are consistent with the hypothesis that CF serum inhibits MCC in vivo in the inflamed mucosa.

Aerosol Therapy of Asthma: Principles and Applications

Aerosols are the mainstay of therapy of reversible airflow obstruction. Currently available aerosols include bronchodilators such as beta-adrenoceptor agonists and anticholinergic agents which may be used alone or together with prophylactic, anti-inflammatory medications such as sodium cromoglycate and steroids. These agents are characterized by primarily topical activity and thus result in minimal systemic effects. By combining these medications in optimum doses, most patients can be readily managed. In patients with severe airway hyperreactivity, aerosols may need to be combined with oral sustained-release theophylline compounds and/or systemic steroids, the latter being used in minimum doses and if possible on alternate days to minimize adrenal suppression and steroid-related systemic complications. In recent years, an improved understanding of aerosol physics, pharmacology and airway physiology has led to greatly improved aerosol therapy with increasing emphasis on metered dose inhalers as the delivery system of choice while nebulizers are used less frequently except in hospital and pediatric applications. The use of intermittent positive-pressure devices for aerosol delivery has decreased considerably as physicians recognize that simpler delivery methods work equally well at much lower cost. While aerosol therapy techniques are now well worked out, research is continuing on methods of improving the efficiency of aerosol delivery and in the development of newer pharmacological agents such as longer-acting adrenoceptor agonists, calcium channel blockers, antagonists of mediators derived from arachidonic acid as well as higher dose aerosolized steroids.