Final answer:
A deviation from the planned clinical pathway due to a patient's decreased oxygen saturation after CABG, resulting in extra days on a ventilator, is a variance.
Step-by-step explanation:
In the scenario described, a patient undergoing coronary artery bypass grafting (CABG) experiences a complication due to chronic tobacco abuse, leading to a decreased oxygen saturation and necessitated prolonged ventilator support. This deviation from the predetermined clinical pathway, which anticipated extubation and discharge from critical care the day after surgery, is referred to as a variance. Variances are differences between planned patient care and the actual care delivered, often requiring a change in care plan to address unforeseen issues.