- second group ("blind group") with capnography monitoring but PACU nurses cannot see the values Other parameters like the time between ventilator's disconnection and the first ventilatory cycle in spontaneous ventilation, the time between ventilator's disconnection and tracheal extubation or laryngeal mask's withdrawal, the minimal SpO2 reached after tracheal extubation or laryngeal mask withdrawal or the length of stay in PACU are also recorded.