Bronchodilator delivery by metered-dose inhaler in mechanically ventilated COPD patients: influence of end-inspiratory pause

The delivery of bronchodilators with a metered-dose inhaler (MDI) and a spacer in mechanically ventilated patients has become widespread practice. However, the various ventilator settings that influence the efficacy of MDI are not well established. Application of an end-inspiratory pause (EIP) during drug delivery has been suggested as one of the factors that might increase the effectiveness of this therapy. To test this, the effect of EIP on the bronchodilation induced by beta2-agonists administered with MDI and a spacer in a group of mechanically ventilated patients with chronic obstructive pulmonary disease (COPD) was examined. Twelve patients with COPD, mechanically ventilated on volume-controlled mode, were prospectively randomized to receive six puffs of salbutamol (100 microg x puff(-1)) either with or without EIP of 5 s duration. Salbutamol was administered with an MDI adapted to the inspiratory limb of the ventilator circuit using an aerosol cloud-enhancer spacer. After a 6 h wash-out, patients were crossed over to receive salbutamol by the alternative mode of administration. Static and dynamic airway pressures, minimum (Rmin) and maximum (Rmax) airflow resistance, the difference between Rmax and Rmin (deltaR), static end-inspiratory respiratory system compliance (Cst,rs) and cardiac frequency (fc) were measured before and at 15, 30 and 60 min after salbutamol administration. Salbutamol caused a significant decrease in dynamic and static airway pressures, Rmin and Rmax. These changes were not influenced by application of EIP and were evident at 15, 30 and 60 min after salbutamol. With and without EIP, Cst,rs,deltaR and fc did not change after salbutamol. In conclusion, salbutamol delivered with a metered-dose inhaler and a spacer device induced significant bronchodilation in mechanically ventilated patients with chronic obstructive pulmonary disease, the magnitude of which was not affected by an end-expiratory pause of 5 s. These results do not support the use of end-inspiratory pause when bronchodilators are administered in adequate doses during controlled mechanical ventilation.

Orthodeoxia and platypnoea after acute organophosphorus poisoning reversed by CPAP: a newly described cause and review of the literature

The case of a 60-year-old male patient, who survived severe organophosphorus poisoning, and subsequently developed platypnoea and orthodeoxia is described. The patient was mechanically ventilated for a long period of time in the intensive care unit. During the weaning trial, he developed platypnoea and orthodeoxia (PaO2 85 mmHg in recumbency, and 40 mmHg in upright position). Interestingly, the patient's orthodeoxia was alleviated on continuous positive airway pressure (CPAP) treatment. This is a newly described cause of the platypnoea-orthodeoxia syndrome. The possible pathophysiological mechanisms are discussed and a review of the reported abnormal states associated with this condition is presented.