Final answer:
The appropriate medication for a client with a low respiratory rate due to morphine toxicity is Naloxone, an opiate antagonist that reverses opioid-induced respiratory depression.
Step-by-step explanation:
If a nurse notes a respiratory rate of 8/min in a client who is receiving morphine via IV bolus following a cesarean birth, the correct medication to administer would be Naloxone. Morphine is a strong opioid analgesic used to treat severe pain, but it can also cause respiratory depression, which is evident by the low respiratory rate. Naloxone is an opiate antagonist that rapidly reverses the respiratory depression caused by opioids without producing analgesic or euphoric effects. It precipitates withdrawal in narcotic-dependent individuals and is used specifically for the reversal of opioid-induced respiratory depression, even though it has a short duration of action and must be given parenterally.