High frequency oscillations improve nasal mucociliary transport

Mechanical chest stimulation as a physiotherapy aid

In patients with lung disorders there is often a build up of mucus inside the lungs which in healthy people is normally removed by the action of cilia on the lung tissue surfaces. In the diseased lung, however, this clearance mechanism may be ineffective and so patients are offered physiotherapy in order to assist the mucus removal process. The consequences of not properly removing the mucus are impaired lung function and a much higher risk of contracting lung infections and suffering consequent permanent scarring of the lung tissues. If unchecked the latter leads ultimately to failure of the lungs and to the patient's death. The most common forms of chest physiotherapy used are percussion coupled with postural drainage and an active cycle of breathing. This requires the patient to lie head downwards on an inclined surface, so that gravity might assist the mucus removal process, whilst the physiotherapist strikes the patient's chest with the hands. The procedure is interspaced by periods of 'huffing and coughing' by the patient to remove the loosened sputum from the body. An alternative to the manual percussion described above is to use machinery to provide the stimulus to the chest. If such a procedure were found to be satisfactory then it would enable more patients to manage their own physiotherapy, may make the required duration of the physiotherapy sessions shorter, and would free much of the professional physiotherapists' time to enable them to assume more of a physiotherapy management role.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of cromolyn sodium in dogs undergoing high-frequency oscillation superimposed on conventional mechanical ventilation

The effects on gas exchange of superimposition of high-frequency oscillation (HFO) (40 Hz) on conventional mechanical ventilation were investigated in mongrel dogs with eucapnic gas exchange on conventional mechanical ventilation (CMV). The dogs were anesthetized, paralyzed, and ventilated with CMV until stable. Oscillation was then superimposed for 15 min, followed by CMV alone for a further 30 min. During HFO superimposed on CMV (CMV-HFO), the arterial carbon dioxide tension (PaCO2) increased from 43.6 +/- 1.2 mm Hg to 47.2 +/- 1.4 mm Hg (p less than 0.02), whereas the arterial oxygen tension (PaO2) did not change at all. The change was inhibited completely by administration of intravenous cromolyn sodium (CS) (6 mg/kg/min). The mean pulmonary arterial pressure (mPAP), cardiac output (CO), pulmonary capillary wedge pressure (PCWP), and pulmonary vascular resistance (PVR) did not change during the experiment. These results demonstrate that CMV-HFO appears to cause CO2 accumulation and eliminates the impaired O2 transfer, and that these effects are inhibited completely by CS administration.

The effect of high-frequency ventilation on non-Newtonian properties of bronchial mucus

We have investigated the changes in the non-Newtonian properties of human bronchial mucus brought about by in vitro high frequency ventilation. This type of ventilation brought about changes in viscous properties, measured during creep and oscillation of the mucus, which would be expected to reduce mucus clearance in vivo. We suggest that any beneficial effects of clinical high-frequency ventilation on respiratory mucus clearance in patients are not brought about by long-term (more than a few seconds) changes in the viscous properties of the mucus itself.

Effect of low frequency air oscillations on nasal mucociliary transport

Air oscillations of 16 Hz and pressure differences of 200 mmHg were applied to the nose of 30 volunteers. The mucociliary transport was measured by the saccharin test. Tests under the same circumstances were performed with and without oscillations on the same person within the same day. There was a significantly faster mucociliary transport during air oscillations. The possible mechanisms for this effect are discussed.

High frequency oscillations and mucociliary transport

Mucociliary transport is influenced by high frequency oscillation of air within the lungs. While some studies suggest that high frequency ventilation may be detrimental, with appropriate techniques, there is no doubt that this has potential as a means of improving the clearance of secretions from the lung.

Duration of antibiotic courses for neonates

A survey of the use of antibiotics in a neonatal unit for two years showed a considerable reduction in the mean duration of courses prescribed without any appreciable change in morbidity.

Protracted diarrhoea of infancy: evidence in support of an autoimmune variant

Circulating autoantibodies to enterocytes were detected by indirect immunofluorescence in 14 out of 25 patients with idiopathic protracted diarrhoea of infancy. Similar specificities were not found in 50 control children with nongastroenterological disorders. The immunofluorescence pattern was more accentuated on the apical border of mature enterocytes. Enterocyte autoantibodies were mainly of IgG class (13/14), but 11 sera were positive for IgM and IgA classes, and five out of 14 positive sera also had the ability to fix complement. Absorption of sera positive for autoantibodies with an IgA coupled immunoabsorbent did not modify the intensity of the staining, indicating that these antibodies were not directed against secretory IgA. High titres and the complement fixing ability of enterocyte autoantibodies indicated a poorer prognosis despite the use of immunosuppressive drugs. Organ specific and non-organ specific autoimmune diseases or corresponding autoantibodies or both were often found in children with enterocyte autoantibodies and their family. These data show the existence of an autoimmune variant of protracted diarrhoea of infancy, despite the rare occurrence of autoimmune diseases in childhood.