During a patient case study, increasing increments of PEEP showed no significant effects until 15 cm H2O was used, at which time the PaO2 improved markedly. This represents the point at which _______________

a. cardiac output decreased
b. airway resistance decreased
c. hemoglobin saturation improved
d. alveolar recruitment probably occurred

ANS: D
Recruitment maneuvers can produce varying results among patients. In patients who respond to an RM, PaO2 increases, PaCO2 decreases, and the change in pressure (?P) required to cause an acceptable VT decreases.