A.Breathing pattern in a patient with recurrent obstructive apneic events as might occur during sleep. PaCO₂ = arterial carbon dioxide concentration; SpO₂ = oxygen saturation; Ve = expired minute ventilation. B.Representation of recurrent activation of the saturation alarm in a patient with sleep apnea (alarm threshold set at 90%). This could possibly lead to alarm fatigue (y-axis = SpO₂).