Which of the following statements is true?
a. Capnography is a useful tool for assessing the effetiveness of oxygenation.
b. Pulse oximetry may be inaccurate in patients with poor peripheral perfusion.
c. When capnometry is used, a numeric reading of exhaled CO2 concentrations is provided without a continuous waveform.
d. Pulse oximetry can alert the clinician to signs of respiratory compromise such as hypoventilation and hyperventilation.