Final answer:
The positive end-expiratory pressure (PEEP) has beneficial effects such as increasing PaO2, lung compliance, decreasing shunt fraction, and increasing functional residual capacity. The correct answer is option A, which includes all of the listed physiological effects.
Step-by-step explanation:
The beneficial physiological effects of positive end-expiratory pressure (PEEP) are diverse and include several key functions: increasing PaO2 for a given FIO2, which helps ensure that the blood is adequately oxygenated; increasing lung compliance, which makes the lungs more pliable and reduces the work required to breathe; decreasing the shunt fraction, which improves the quality of gas exchange by reducing the amount of blood that bypasses the gas exchange process; and expanding the functional residual capacity (FRC) of the lungs, which implicates a reserve of air in the lungs after passive expiration, enhancing gas exchange and preventing airway collapse.
Considering these physiological benefits, the correct answer to the student's question regarding the beneficial physiological effects of PEEP would be: increased PaO2 for given FIO2, increased lung compliance, decreased shunt fraction, and increased functional residual capacity. Therefore, the answer is option A) I, II, III, and IV.