[Increase in functional residual capacity induced by positive end-expiratory pressure. Prediction using the thoracopulmonary pressure curve]. / Augmentation de la capacité résiduelle fonctionnelle induite par la ventilation en pression positive expiratoire. Prédiction par la courbe pression-volume thoracopulmonaire.

Prediction of FRC using a respiratory P-V curve (2 1 syringe method) has been tested in eight patients with normal lungs and in 12 ARDS patients. FRC was measured using nitrogen dilution technique with a closed circuit. Correlation between measured and predicted FRC was excellent, especially when the expiratory limb of the P-V curve was used (r = 0.92, in patients with pulmonary edema, and r = 0,97 when patients were evaluated after a few weeks). PEEP induced increase in FRC was larger between 10 and 20 cmH2O than between 0 and 10 cmH2O. As expected, Qs/Qt decrease was correlated with the FRC augmentation.

[Contamination of an oxygen delivery circuit by compressed air]. / Contamination d'un circuit d'oxygène par de l'air comprimé.

Routine checking of the FIO2 of a mixture delivered by a ventilator revealed large discrepancies between the FIO2 assigned and that effectively delivered, the latter being low. Measurements of FIO2 at the wall outlets showed the O2 delivery pipeline to be contaminated by compressed air. By disconnecting all the ventilators supplied by this pipeline one after the other, one ventilator, or rather its blender, was found responsible.

Differential ventilation in unilateral lung disease: effects on respiratory mechanics and gas exchange.

Conventional PEEP ventilation has been recently reported to be deleterious in some cases of ARF with unilateral pneumonia. In such respect, two cases of unilateral bacterial pneumonia were intubated with a Carlens tracheal tube. Measurement of tidal volume, static compliance, and functional residual capacity of each lung showed marked inequality. Subsequently, both patients were ventilated with a selective distribution circuit, allowing the introduction of a PEEP valve in the expiratory line of the diseased lung. Evident improvement in blood gases was obtained within 24 hours, as tidal volume, static compliance, and FRC of the diseased lung were markedly improved. In one case equalisation of V/Q ratio was documented using the 81m Kr method. Final recovery was obtained in one case.

[Acute respiratory failure: comparison of spontaneous ventilation with continuous positive airway pressure (CPAP) and mechanical ventilation with positive and expiratory pressure (CPPV) in 6 cases (author's transl)]. / Insuffisasnce respiratoire aiguë de l'adulte: comparaison des effets hémodynamiques et respiratoires de la pression expiratoire positive en ventilation spontanée et en ventilation artificielle.

The hemodynamic and respiratory effects of spontaneous ventilation with continuous positive airway pressure (CPAP) and mechanical ventilation with positive and expiratory pressure (CPPV) were compared in six patients with acute respiratory failure. Arterial and mixed venous gases, cardiac output, oxygen delivery and consumption, airway and oesophageal pressures were measured, with each patient on intermittent positive pressure ventilation (IPPV), CPAP and CPPV with the same level of positive and expiratory pressure (PEEP = 20 cmH2O). CPAP was as efficient as CPPV for improving arterial oxygenation. Cardiac output was higher on CPAP than on CPPV due to a lower intra-thoracic pressure with spontaneous ventilation, thus oxygene transport was higher with this methode. However total oxygene consumption and PaCO2 were slightly increased with CPAP due to a higher breathing's work. So, CPAP is as efficient as CPPV at the same level of PEEP in improving intra-pulmonary shunt and PaO2, without adversely affecting cardiac output.