Changes in occlusion pressure (P0.1) and breathing pattern during pressure support ventilation
- Pierre-François O Perrigaulta,
- Yvan H Pouzerattea,
- Samir Jabera,
- Xavier J Capdevilab,
- Maurice Hayotc,
- Gilles Boccaraa,
- Michele Ramonatxoc,
- Pascal Colsona
- aDepartement d’Anesthésie Réanimation B, bDepartement d’Anesthésie Réanimation A, cHopital St Eloi et Lapeyronie, Montpellier, France Service d’Exploration de la Fonction Respiratoire, Hopital Arnaud de Villeneuve, Montpellier, France
- Dr P F Perrigault, Departement d’Anesthésie Réanimation B, Hopital St Eloi, Av Bertin Sans, Montpellier, 34295 Cedex, France.
- Received 26 January 1998
- Revision requested 31 March 1998
- Revised 3 July 1998
- Accepted 7 October 1998
Abstract
BACKGROUND The purpose of this study was to investigate changes in breathing pattern, neuromuscular drive (P0.1), and activity of the sternocleidomastoid muscles (SCM) during a gradual reduction in pressure support ventilation (PSV) in patients being weaned off controlled mechanical ventilation.
METHODS Eight non-COPD patients recovering from acute respiratory failure were included in this prospective interventional study. All patients were unable to tolerate discontinuation from mechanical ventilation. Each patient was evaluated during a period of spontaneous breathing and during PSV. Four successive levels of PSV were assessed in the following order: 20 cm H2O (PS20), 15 cm H2O (PS15), 10 cm H2O (PS10), and 5 cm H2O (PS5).
RESULTS When pressure support was reduced from PS20 to PS10 the respiratory rate (f) and the rapid shallow breathing index (f/Vt) significantly increased and tidal volume (Vt) significantly decreased. These parameters did not vary when pressure support was reduced from PS10 to PS5. Conversely, P0.1 varied negligibly between PS20 and PS15 but increased significantly at low PSV levels. P0.1 values were always greater than 2.9 cm H2O (4.1 (1.1) cm H2O) when SCM activity was present. When contraction of the SCM muscles reappeared the P0.1 was the only parameter that changed significantly.
CONCLUSIONS In postoperative septic patients the value of P0.1 seems to be more useful than breathing pattern parameters for setting the optimal level of pressure assistance during PSV.
