A postoperative client receiving IV opioid patient-controlled analgesia is also receiving supplemental oxygen. Which statement best explains the purpose of capnography?
1It measures arterial oxygen concentration and replaces pulse oximetry and sedation assessment.
2It measures delivered opioid dose and prevents the client from activating the device too often.
3It continuously trends exhaled carbon dioxide and respiratory rate to help detect hypoventilation.✓ Correct answer
4It measures blood pressure continuously and identifies hypotension caused by opioid administration.
Explanation
Capnography trends exhaled carbon dioxide, respiratory pattern, and respiratory rate, helping detect opioid-related hypoventilation when supplemental oxygen may delay a fall in oxygen saturation. It complements rather than replaces pulse oximetry, level-of-consciousness assessment, and clinical evaluation. It does not measure opioid dose, arterial oxygen concentration, or blood pressure.
Clinical reasoning summary Supplemental oxygen can keep SpO2 deceptively stable while ventilation declines. Capnography provides a continuous trend of exhaled carbon dioxide and respiratory rate, but it must be interpreted together with oxygen saturation, sedation level, and bedside assessment.