Assessment of thoraco-abdominal asynchrony.

Thoraco-abdominal asynchrony is often observed in many respiratory disorders and/or respiratory muscle dysfunctions and clinically assessed as a sign of respiratory distress and increased work of breathing. This review describes the assessment of thoraco-abdominal asynchrony by respiratory inductance plethysmography. Visual inspection of the Konno-Mead plot yields information about the relative contribution of the RC and the ABD to respiration and about respiratory muscle dysfunction in selected patients. The monitoring of thoraco-abdominal asynchrony is a useful, non-invasive indicator of respiratory muscle load or respiratory muscle dysfunction and can be used to determine response to therapy in individual patients. The technique is limited by the fact that it does not detect respiratory muscle fatigue and that the occurrence of TAA does not always correspond to a clinically relevant respiratory problem, especially in the neonatal period.

The effect of epinephrine by nebulization on measures of airway obstruction in patients with acute severe croup.

OBJECTIVES: To demonstrate that tests of pulmonary function applicable to sick infants and small children with acute severe viral croup would provide clear, objective evidence of responsiveness to therapy with nebulized epinephrine. STUDY DESIGN: Oesophageal pressure changes and airflows at the mouth were measured in 17 patients with acute severe croup, before and after nebulization with epinephrine. RESULTS: In 12 of the 17 patients there was a significant improvement in respiratory mechanics following epinephrine nebulization. Six of the 12 patients who responded to adrenaline also received 0.9% saline by nebulization, without improvement. No measures derived from combined flow and volume data showed any statistically significant change following epinephrine nebulization. Measures combining flow and pressure data, specifically inspiratory airway resistance, expiratory airway resistance, work of breathing, rate of work of breathing and volume for effort, showed changes of 26%, 33%, 16%, 16% and 46% respectively. The most statistically significant measures were pressure-rate product, pressure-time integral, oesophageal pressure alone and expiratory resistance. These changes persisted for at least 10 min after inhalation although there was some evidence of decline in pharmacologic effect at that time. CONCLUSIONS: Nebulized epinephrine results in a short-lived improvement in some but not all patients with croup. This reduction in respiratory effort occurs secondary to a decline in inspiratory and expiratory airway resistance. Oesophageal pressures measured via a feeding tube are satisfactory for quantification of the acute response and may be a useful continuous monitoring device. Flow measurements are unhelpful, and continuous administration of nebulized epinephrine should be investigated.