Heart frequency, blood pressure and oxygenation. Anaesthesia with pentobarbital sodium resulted in reduced heart frequency (300-400 min 21 ) and mean blood pressure (50-60 mmHg), compared to average data of unsedated mice. ECG (data not shown), HF and BP remained unchanged throughout ventilation and were not significantly different between the groups (Fig. 2 ). This demonstrates that ventilation and recruitment strategy did not affect the circulation. The fluid support with 200L NaCl per hour in all groups was adequate to keep blood pressure stable. Oxygen saturation, measured by pulsoxymetry, was over 90% in all mice at all times (data not shown).