Procedural sedation and analgesia (PSA) is a technique in which a sedating/dissociative medication is given, usually along with an analgesic medication, in order to perform non-surgical procedures on a patient. The overall goal is to induce a decreased level of consciousness while maintaining the patient's ability to breathe on their own. Airway protective reflexes are not compromised by this process and therefore endotracheal intubation is not required. PSA is commonly used in the emergency department, in addition to the operating room.
Medical uses
This technique is often used in the emergency department for the performance of painful or uncomfortable procedures. Common purposes include: laceration repair setting fractures draining abscesses reducing dislocations performing endoscopy for cardioversion during various dental procedures during transesophageal echocardiogram and certain imaging or minor procedures where the patient is unable (or unwilling) to keep still—especially children
Contraindications
There are no absolute reasons that immediately disqualify a patient from receiving PSA. However, a patient's age, medical comorbidities, or evidence of a difficult airway are important considerations.
Age
Although there is no age limit for PSA, the elderly have a greater chance of complications such as longer than intended sedation time, increased sensitivity to medications, adverse effects of medications, and higher than expected drug levels due to difficulty clearing the drugs. To help reduce risk of complications, consider a less aggressive approach to PSA, including starting with a smaller dose than given for non-elderly patients, giving the medication slowly, giving repeat doses of the medications less often.
Comorbidities
Patients with serious medical conditions are at greater chance for negative side effects after receiving PSA. Examples of comorbidities include heart failure, COPD, neuromuscular disease. Use the ASA Classification to predict a patient's risk for serious complications from PSA, such as hypotension or respiratory depression. Generally, patients with ASA Class III or greater are more likely to develop such complications. Similar to previously described, consider starting with a smaller dose, giving the medication slowly, and giving repeat doses of the medications less often to decrease risk of complications associated with comorbidities.
Difficult airway
An airway is assessed by the patient's ability or the physician's ability to oxygenate (provide oxygen) or ventilate (exhale carbon dioxide). Examples of a difficult airway include a thick neck/obese patient, head and neck structural abnormalities, and lung disease. The problem is not that the patient will not respond appropriately to medications, as is the case with older patients or those with medical comorbidities, but that if there is a complication, it will be more difficult for the physician to protect the patient's airway and save them from complications. It is generally advised to consider alternatives to PSA if the patient is assessed to have a difficult airway. Measures such as reducing starting dose, giving drugs slowly, and redosing less frequently will not change risk of PSA complications in a patient with a difficult airway.
Spectrum of Sedation
While procedural sedation is often used to avoid airway intervention, sedation is a continuum and a patient can easily slip into a deeper state. For this reason, a physician who is performing PSA should be prepared to care for a patient at least one level of sedation greater than that intended. In order to do this, a practitioner must be able to recognize the level of sedation and understand the increasing cardiopulmonary risk that is associated with deeper sedation.
The American Society of Anesthesiologists defines the continuum of sedation as follows:
There is another type of sedation known as dissociative sedation. It causes profound amnesia but allows spontaneous respiration, cardiopulmonary stability, and airway reflexes are still intact. Ketamine is a commonly used drug that can cause this type of sedation.