Abstract

BIANCHI*, Domingo A. Determinación de peep clínicamente útil en los ventiladores de las modernas máquinas de anestesia. Anest Analg Reanim [online]. 2009, vol.22, n.2, pp.4-11. ISSN 1688-1273.

SUMMARY The technological development has allowed us to incorporated electronic positive end-expiratory pressure (PEEP) to the new anesthesia machines, as well as different ventilation modes and curves of pressure/volume and flow/volume. The aim of this study was to find the best value of PEEP of each patient, that determined the most significative increase of the pulmonary static compliance. 20 patients were analyzed, 66 years old average and 77 kg of weight, scheduled for cardiac surgery with extracorporeal circulation. The ventilatory pattern used was : controlled ventilation with a square wave of inspiratory flow, inspiratory pause of 30%, tidal volume of 7 ml/kg, inspired fraction of oxygen of 0.6 and inspiration/espiration relation: 1:2. Serial manual maneuvers of recruitment were done, and after 5 minutes with a fresh gas flow of 2 l/min the following observations and calculations were made: static pulmonary compliance, airway pressure at the point of flexion and at the point of maximum curvature of the inspiratory and espiratory part of the curve pressure/ volume respectively. The value of PEEP observed at those points and at the point of flexion with 3 cm H₂O were registered, and the value of static compliance at each moment was made, trying to find the optimal PEEP. Samples were taken for gasometries in each patient. The average values were : point of flexion: 5 + - 1.6 cm H₂O, point of maximum curve: 7 + - 2.2 cm H₂O static compliance: 42 + - 12 ml/cm H₂O, the best value of PEEP: 7.9 + - 2 cm H₂O, wich determined an increase of compliance: 65 + - 12 cm H₂O (53%). With and usefull PEEP the PaFi average was : 387 mmHg, and PaCO₂ 40 mm Hg. In this study with the common resources of our anesthesia machines, a significative increase of static compliance was observed, due to a usefull PEEP. That value could be obtained with the addition of 3 cm H₂O to the pressure at the flexion point or 1 cm H₂0 to t he airway pressure at the point of maximum curvature

Keywords : PEEP, controlled ventilation, anesthesia machines.

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