Principles of deep sedation

Deep sedation is indicated when nonpharmacological methods, local or regional anaesthesia and oral analgesics are inadequate for the procedure, and a deeper level of sedation is required than conscious sedation. Deep sedation should achieve analgesia and deeper depression of conscious state so that the patient cannot be easily roused, but responds after repeated or painful stimulation.

Overview of procedural sedation and analgesia levels  outlines the interventions commonly used to achieve deep sedation. Factors influencing the choice of drug used for procedural sedation and analgesia  lists factors influencing drug choice, and Commonly used drugs for procedural sedation and analgesia  outlines the properties of commonly used drugs for procedural sedation and analgesia.

Ketamine or propofol alone (at doses higher than those used for conscious sedation) may be sufficient to produce deep sedation, although propofol does not provide analgesia. In children, if intravenous cannulation is not immediately possible (eg the child is distressed and the situation is urgent), a single dose of intramuscular ketamine may achieve deep sedation. Intravenous opioids may be added to ketamine or propofol to provide analgesia during the procedure; however, they cannot be used alone because the dose of opioid required to produce deep sedation is associated with opioid-induced ventilatory impairment.

It is easy to inadvertently proceed from deep sedation to general anaesthesia. Staff involved in delivering or monitoring deep sedation must be able to assess the level of sedation achieved, manage general anaesthesia if it were to occur, and have resuscitation skills relevant to the patient’s age and condition; see Requirements for procedural sedation and analgesia. To reduce the risk of achieving deeper sedation than intended (ie general anaesthesia), drugs must be titrated cautiously to effect.

Do not continue the procedure if deep sedation proves to be inadequate; it may be necessary to use general anaesthesia, which is beyond the scope of these guidelines—seek expert advice.