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. PSA is commonly used in the emergency department, in addition to the operating room. While PSA is considered safe and has low rates of complication, it is important to conduct a pre-procedural assessment, determine any contraindications to PSA, choose the most appropriate sedative agent, and monitor the patient for potential complications both during and after the procedure.
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.
Sedative agents
Propofol Propofol is a non-barbiturate derivative that is thought to act by stimulating inhibitory GABA receptors and blocking excitatory NMDA receptors. It takes 40 seconds for the effects of propofol to kick in, and effects last six minutes. Propofol has both sedative and amnestic effects, but provides no analgesia. Adverse effects to look out for include hypotension (low blood pressure) and respiratory depression, manifested as mild drops in oxygen saturation levels. Propofol is also painful when administered intravenously, therefore, lidocaine is commonly used as a pretreatment to help decrease the pain associated with administering propofol. Additionally, it has antiemetic properties that are also useful in these types of procedures.
Etomidate Etomidate is an imidazole derivative, commonly used for the induction of general anesthesia. Effects kick in almost immediately, within 5–15 seconds, and last 5–15 minutes. Etomidate carries sedative effects only; it does not provide pain relief. Side effects of etomidate include myoclonus (involuntary muscle jerking) and respiratory depression. One of the major benefits of etomidate is that it does not cause cardiovascular or respiratory instability. This makes it a potentially more preferable choice for those with already lower blood pressure.
Midazolam Midazolam is a benzodiazepine that acts by stimulating inhibitory GABA receptors. Effects are seen within 2–5 minutes, and last 30–60 minutes. Its main effect is anxiolysis, helping to reduce feelings of anxiety, and amnestic effects, helping the patient to forget memories associated with the procedure. It provides no analgesia, so it was commonly used with fentanyl for effective PSA prior to propofol and etomidate. Midazolam collects in the body's fatty tissues, so a possible complication includes prolonged sedation. As a result, the elderly, the obese, and those with kidney or liver disease are more vulnerable to prolonged sedation with midazolam. Respiratory depression is also associated with midazolam when given in high doses.
… excerpt ends here. Continue reading the full article.
