Tomography assessment of lung hyper inflation areas within cats in a pressure controlled ventilation staggered

Mechanical ventilation is essential for oxygen supply during anesthesia. Some strategies are related to lung injury associated with mechanical ventilation. 10 cats, 4±1 kg, 1-6 years old, induced and maintained with propofol (6mg/kg, 0,5mg/kg/min) placed in supine position, subjected to pressure controlled ventilation (PCV) in oxygen at 40% with 5cmH2O peak pressure in 'ZEEP' for 20 minutes, rising in 2cmH2O installments peak pressure every five minutes until it reached 15cmH2O. Moments P5, P7, P9, P11, P13, P15. Respiratory rate and inspiratory time were held on 15 movements per minute and 1 second regardless their EtCO2. Muscle relaxation achieved by rocuronium bollus (1mg/kg/IV). Immediately, at each increase on pressure was performed a 4 seconds' inspiratory pause to allow the five millimeters CT slice of diaphragmatic region followed by hemogasometric and cardiorespiratory variables collected. P5 had the smallest hyperinflated area (3,24±4,02) Compared to other moments. P5 blood gases showed acidaemia (7,257±0,08) for mild respiratory acidosis (45±9.2) with good oxygenation (178±40.8mmHg) compared to other times which obtained reduction of CO2 and an increased pH. As the increase in peak pressure was observed increased distension of the lung parenchyma, a fact related to possible risk of lung injury in prolonged periods. 5cmH2O pressure was demonstrated to be less harmful due to its lower hyper inflated areas that other moments, even with a low pH and high CO2, being corrected by increasing respiratory rate.