What should be closely monitored continuously during treatment with parenteral narcotics?

When treating a patient with parenteral narcotics, closely monitoring the patient's cardiac function and oxygen saturation levels is crucial due to the effects of narcotics on respiratory drive and cardiovascular stability. Narcotics can lead to respiratory depression, which might compromise oxygen saturation and can ultimately result in hypoxia if not promptly addressed.

Additionally, narcotics may affect heart rate and rhythm due to their sedative properties, which can lead to bradycardia or other abnormal heart rhythms. Monitoring these parameters allows for timely intervention if the patient shows signs of respiratory distress or significant changes in cardiovascular status.

While other choices involve important aspects of patient care, such as consciousness and blood sugar, the specific risks associated with narcotic use prioritize the need for continuous assessment of cardiac and oxygen saturation levels to ensure patient safety and effective treatment outcomes.