Efectos pulmonares y hemodinámicos del reclutamiento alveolar progresivo durante la anestesia en el perro

Abstract

Recruitment manoeuvres can be used to reverse atelectasis during general anaesthesia, thus improving lung mechanics and gas exchange. Nevertheless, they present some risks, as the development of barotrauma and the haemodynamic impairment. These manoeuvres have not been studied in detail in canine patients. Objectives This study was divided in three sub-studies to achieve different objectives: first, using healthy rabbit lungs, the aim was to explore the range of pressures that can be safely used to fully recruit the lung without causing barotrauma (Study 1). Second study was performed to evaluate the effects of a stepwise recruitment manoeuvre on cardiac output (CO) in mechanically ventilated healthy dogs, with or without a previous fluid load (Study 2). The third study was performed to evaluate the effects of a stepwise lung recruitment manoeuvre on dynamic lung compliance and gas exchange in clinical canine patients (Study 3). Materials and Methods Study 1 A prospective, randomized, experimental study, using fourteen healthy young rabbits (aged 12 weeks old), was performed. Animals were euthanized, the thorax and both pleural spaces were opened, and they were randomized into two recruitment manoeuvre groups. Positive end-expiratory pressure (PEEP) was incrementally increased by 5 cmH2O from 0 cmH2O to 20 cmH2O (PEEP-20 group) or 50 cmH2O (PEEP-50 group). A driving pressure of 15 cmH2O was maintained in both groups. Once maximal PEEPs and their corresponding maximal inspiratory pressures were reached, driving pressure was Summary 142 increased by 5 cmH2O until the macroscopic barotrauma occurred. Three macroscopic conditions were defined: anatomic open lung, overdistension threshold and barotrauma. Maximal inspiratory pressure, PEEP and driving pressure were measured in the three lung conditions. A pressure safety range (defined as the difference between barotrauma maximal inspiratory pressure and anatomic open lung maximal inspiratory pressure) was determined in both groups