Figure 6(a) shows the result of successful weaning after a period of mechanical ventilation. The patient was put on a pH value of 7.4 and took control of his own acidbase balance after starting weaning from the mechanical ventilation (at ↓) within a few minutes at a slightly lower pH value. The registration shown in figure 6(b) shows an unsuccessful weaning at point “I”, which is the reason for the anaesthetist deciding to restart the mechanical ventilation at point “II”.