A 537 kg Warmblood gelding was referred for acute abdominal pain and underwent exploratory laparotomy. During general anesthesia, despite the use of intermittent positive pressure ventilation (IPPV), it developed a progressive severe arterial hypoxemia (PaO2 68.5 mmHg). By means of high inspiratory pressures (PIP), combined with positive end expiratory pressure (PEEP), oxygenation was successfully improved throughout the procedure until the end of anesthesia. During the highest airway pressures achieved with the alveolar recruitment maneuver, hypotension developed as normal sequel and was successfully treated with intravenous inotropes, colloids and fluids
