Final answer:
Ventilator-associated pneumonia (VAP) is the most common complication associated with long-term mechanical ventilation through a tracheostomy tube, which occurs due to bacterial contamination of medical equipment.
Step-by-step explanation:
The complication most commonly associated with long-term mechanical ventilation, especially through a tracheostomy tube, is pneumonia. This is often referred to as ventilator-associated pneumonia (VAP) and is a result of bacteria introduced via contaminated ventilators, intubation, or other medical equipment. Factors contributing to VAP include prolonged mechanical ventilation, changes in lung compliance and resistance, ventilator circuit changes, and inadequate infection control practices. This type of pneumonia can become a serious issue for patients, potentially leading to worsened outcomes and prolonged hospital stays.