Conscious Sedation

Conscious Sedation

‘Conscious sedation’ is a monitored state of altered consciousness that can be employed (supplemented with local/regional anaesthesia), to carryout diagnostic/short therapeutic/dental procedures in apprehensive subjects or medically compromised patients, in place of general anaesthesia. It allows the operative procedure to be performed with minimal physiologic and psychologic stress. In conscious sedation, drugs are used to produce a state of CNS depression (but not unconsciousness), sufficient to withstand the trespass of the procedure, while maintaining communication with the patient, who at the same time responds to commands and is able to maintain a patent airway. The difference between conscious sedation and anaesthesia is one of degree. The protective airway and other reflexes are not lost, making it safer. Drugs used for conscious sedation are:

Diazepam

It is injected i.v. in small (1–2 mg) repeated doses or by slow infusion until the desired level of sedation is produced indicated by relaxation, indifference, slurring of speech, ptosis, etc. Further injection is stopped, after which this state lasts for about 1 hour and psychomotor impairment persists for 6–24 hours; an escort is needed to take back the patient home. Flumazenil can be used to reverse the sedation, but repeated doses are needed.

Midazolam (i.v.) is a shorter acting alternative to diazepam. Oral diazepam administered 1 hr before is also used with the limitation that level of sedation cannot be titrated. The patient remains sedated (not roadworthy) for several hours.

Propofol

Because of brief action, it has to be administered by continuous i.v. infusion regulated by infusion pump throughout the procedure. However, level of sedation can be altered during the procedure and recovery is relatively quick, permitting early discharge of the patient.

Nitrous oxide

The patient is made to breathe 100% oxygen through a nose piece or hood and N2O is added in 10% increments (to a maximum of 50%) till the desired level of sedation assessed by constant verbal contact is obtained. This is maintained till the procedure is performed. Thereafter, N2O is switched off, but 100% O2 is continued for next 5 min. The patient is generally roadworthy in 30–60 min.

Fentanyl

Injected i.v. (1–2 μg/kg every 15–30 min), it can be used alone or in combination with midazolam/ propofol.