Would want to check your state guidelines.
Below is from 2006 AMA CPT Assistant article on Moderate sedation
Question: If the physician does not administer the agent, are the moderate sedation codes appropriately reported?
Answer: In the case of 99143-99145 where the physician is performing the diagnostic or therapeutic service provides the sedation and the presence of an independent, trained observer to assist in the monitoring of the patient's level of consciousness and physiological status is required, it is appropriate that the agent(s) be administered by the independent, trained observer under the orders of the physician performing the diagnostic or therapeutic service.
Clinical Example: 99144
A patient 5 years of age or older presents with a complaint necessitating performance of some procedure or service (ie, the "supported procedure"), in support for which moderate sedation is deemed clinically appropriate. The treating physician will perform both the supported procedure and the moderate sedation service.
Description of Procedure: 99144
The physician supervises the administration and induction of the sedating agent, with or without an analgesic, initiated by the independent, trained observer. The patient is observed until a safe and effective level of moderate sedation is achieved. The physician, assisted by the independent, trained observer, continually assesses the patient's level of consciousness and physiological status throughout the performance of the supported procedure. Additional doses of sedating agent are ordered by the physician, as needed, to maintain the achieved level of sedation for the supported procedure.
Clinical Example: 99145
A patient 5 years of age or older presents with a complaint necessitating performance of some procedure or service (ie, the "supported procedure"), in support for which moderate sedation is deemed clinically appropriate. The treating physician will perform both the supported procedure and the moderate sedation service.
Description of Procedure: 99145
The physician, assisted by the independent, trained observer, continually assesses the patient's level of consciousness and physiological status throughout the performance of the supported procedure. Additional doses of sedating agent are ordered by the physician, as needed, to maintain the achieved level of sedation for the supported procedure.