Which of the following control modes of ventilation consists of ventilator output automatically following a varying input (e.g., volume or flow generated by the patient)?

a. Servo c. Neural network
b. Optimal d. Knowledge-based

ANS: A
An example of a servo-controlled mode is the proportional assist mode, in which the instantane-ous value of pressure is proportional to the instantaneous volume or flow generated by the pa-tient. The optimal control type has one ventilator set-point automatically adjusted to optimize an-other set-point according to some model of system behavior, and the output can be maximized or minimized dynamically. The artificial neural network is based on acceptable arterial blood gases to maintain patient ventilation (experimental). The knowledge-based control type has set-points that are automatically adjusted according to a rule-based expert system such as end-tidal carbon dioxide.