Influence of respiratory behavior on ventilation, respiratory work and intrinsic PEEP during noninvasive nasal pressure support ventilation in normal subjects.

Background: In clinical practice, patients have different inspiratory behaviors during noninvasive pressure support ventilation (PSV): some breathe quietly, others actively help PSV by an additional effort, and others even resist the inspiratory pressure of PSV.

Objective: What is the influence of patient collaboration (inspiratory behavior) on the efficiency of PSV?

Methods: We ventilated 10 normal subjects with nasal PSV (inspiratory/expiratory: 10/0 and 15/5 cm H(2)O) and measured their flow and volume with a pneumotachograph and their esophageal and gastric pressures during three different respiratory voluntary behaviors: relaxed inspiration, active inspiratory work and resisted inspiration.

Results: When compared with relaxed inspiration with 10/0 cm H(2)O PSV: (1) an active inspiratory effort increased tidal volume (from 789 +/- 356 to 1,046 +/- 586 ml; p = 0.

Effects of nasal pressure support on ventilation and inspiratory work in normocapnic and hypercapnic patients with stable COPD.

Objectives: To assess and compare the effect of nasal continuous positive airway pressure (nCPAP), inspiratory pressure support (PSV), and bilevel positive airway pressure (biPAP) on ventilatory parameters and inspiratory work (WOB) in normocapnic and hypercapnic patients with stable COPD.

Methods: While administering nasal pressure support to 10 normocapnic and 10 hypercapnic patients with COPD, we measured airflow and volume with a pneumotachograph as well as esophageal and gastric pressures under nCPAP, PSV, and biPAP conditions.

Results: nCPAP had no influence on ventilatory parameters but decreased WOB and transdiaphragmatic work (Wdi) at 10 cm H(2)O of pressure in both groups.