Procedural sedation and analgesia

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Procedural sedation and analgesia
MeSHD016292
MedlinePlus007409

Procedural sedation and analgesia (PSA) is a technique in which a sedating/ dissociative medication is administered often in combination with analgesics. It allows a patient to undergo painful procedures by inducing decreased levels of consciousness but not requiring intubation as the patient ventilates spontaneously. Additionally, airway protective reflexes are not compromised by this process. [1] It is commonly used in the emergency medicine setting in addition to operating-room and non-operating-room procedures.

Medical uses[edit]

This technique is often used in the emergency department for the performance of painful or uncomfortable procedures. Common purposes include:

Continuum of Sedation[edit]

Although the goal of procedural sedation is often to avoid airway intervention, it is important to understand that 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.[1] 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. [3]

The American Society of Anesthesiologists defines the continuum of sedation as follows:[4]

Minimal Sedation Moderate Sedation Deep Sedation General Anesthesia
Responsiveness Normal to verbal stimulus Purposeful response to verbal or tactile stimulus Purposeful to repeated or painful stimulus Unarousable, even to painful stimulus
Airway Unaffected No intervention required Intervention may be required Intervention often required
Ventilation Unaffected Adequate May be inadequate Frequently inadequate
Cardiovasc Function Unaffected Usually maintained Usually maintained May be impaired

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. [3]

Agents used[edit]

Sedatives/dissociative agents[edit]

  • Propofol[5]a non barbiturate anesthetic that most likely has an activating effect on the GABA receptor. It is given in the vein and is useful in procedural sedation because it has a quick onset and emergence time. Additionally, it has antiemetic properties that are also useful in these types of procedures.[6]
  • Ketamine acts partially as an antagonist to the NMDA receptor. It causes hypnotic and analgesic effects but most of its uses today are focused on analgesia. As with propofol it has a quick onset and offset.[6]
  • Etomidate is used mainly for induction of general anesthesia. The major benefit to using this is that it has minimal effect on cardiovascular and respiratory function. For this reason, it is often used on those with cardiovascular diseases and the elderly. [6]
  • Midazolam[5] is a Benzodiazepine used in procedural sedation. Benzodiazepines are used because of the anxiolysis and amnestic properties. Of the benzodiazepines, midazolam is most commonly used for its quick onset and offset. [6]
  • Dexmedetomidine is a more recent agent used in this process. It is an alpha-2 adrenergic agonist that causes sedation and does have some analgesic properties. It has minimal effect on respiratory function. It will effect cardiac function as the dose increases. [6]

Analgesics[edit]

  • Opioids – This class of drugs are used to suppress pain by acting on various opioid receptors, primarily Mu, in within the nervous system. They will cause some dose dependent cardiopulmonary suppression. [6] They have addictive properties and have led to the Opioid epidemic. When used for procedural sedation these are started at low dose then titrated to reach the desired effect. [1]
    • Fentanyl is a synthetic opioid that is 100 times more potent than morphine when it comes to pain control. It does not contain amnestic or sedative properties so it is typically used with a sedative like propofol to achieve procedural sedation. It is useful for those with a morphine allergy as it is unlikely to cause a reaction. [3]
    • Morphine performs similarly to fentanyl when used for PSA. The major difference is the onset time. It takes between 10 and 30 minutes for morphine to reach the desired effect. It is also more likely to induce hypotension, aka low blood pressure, due to the Histamine release it causes.[1]
  • Ketamine: As stated, it has both analgesic and sedative properties. It can be useful as an analgesic agent because small doses of ketamine have been found to be safer than fentanyl when used in combination with propofol.[7]

Assessment[edit]

As with any type of anesthesia a patient should have some sort of pre-assessment. The American Society of Anesthesiologists uses a classification system to categorize patients based on risk. Patients should be have a Medical history taken on them including a history of anesthesia as well as a physical exam. These things contribute to the ASA physical status classification system. This system starts at ASA 1 which is a healthy individual and escalates to ASA 6 which is a brain dead individual. [3] It is safe to perform sedation in the emergency room on patients who are ASA1 or 2. If the patient is ASA 3 or 4 additional resources might be needed, such as a person with more training in procedural sedation, an anesthesiologist. [1] Furthermore, before a trained professional performs PSA an Informed consent should be completed. [3]

Airway assessment is one of the most important parts of the physical exam when done as part of the pre-procedure work-up. There is always a risk that a patient is sedated more heavily than intended and consequently require some sort of airway intervention. Therefore, the caregiver should perform an airway exam that includes a Mallampati score, mouth opening assessment, and Thyromental distance. If the patient is deemed to have a difficult airway, there should be adequate resources if airway intervention is required. These includes things like a Glidescope, fiberscope optic, and an intubating Laryngeal mask airway. [3]

Management[edit]

Fasting[edit]

For most agents the person should have had nothing to eat for at least six hours. Clear fluids can be allowed up to two hours before the procedure. An exception to this may be with ketamine in children where fasting may be unnecessary. However, in the emergency department setting, conscious sedation is usually administered without waiting the full six hours unless there is clear evidence that the patient may not be able to maintain his/her airway on their own.[8]

Monitoring[edit]

Visual assessment is an important part of PSA. To quantify the level of consciousness, the physician uses different levels of stimulation and observes the patient's response. Additionally, ventilatory rate can be visually monitored to give the caretakers an idea of pulmonary function. [1] Monitors are also useful for PSA safety. These include cardiac monitoring, pulse oximetry, blood pressure cuff, and an end tidal carbon dioxide monitor. [3]

Discharge criteria[edit]

Patient being monitored following anesthesia

There are a few criteria for discharging a patient who has undergone procedural sedation. The recovery time for a patient to be ready for discharge varies but is typically 60-120 minutes. The criteria are as follows:

  1. Patient must be stable from a cardiovascular standpoint and have an open airway.
  2. The patient should be easy to arouse and have intact reflexes such as a gag and cough reflex.
  3. He/she should be approaching their baseline in terms of talking and sitting up.
  4. The patient should be properly hydrated.
  5. In a special population patient, such as a very young or mentally handicapped patient, he/she should be about as responsive as they were pre-sedation.[9]

Complications[edit]

PSA can cause several complications. These include allergic reactions, over sedation, respiratory depression, and hemodynamic effects. These typically depend on the sedative agent used. Some agents are more likely to cause complications than others. All sedative agents can cause complications if not used properly. Titration is a common technique used to reduce complications. For some agents antagonists are available that can be used to reverse the effects. Additionally, a person is assigned to monitor the status of the patient and should be able to recognize the complications of PSA and know how to respond accordingly. [1]

Safety[edit]

Procedural sedation can be safely performed in an emergency department if structured sedation protocols are followed.[10]

Electrocardiography, pulse oximetry, capnography and blood pressure monitoring are essential, as is the use of supplementary oxygen.

Controversies[edit]

Some resistance to sedation techniques used outside the operating room by non-anesthetists has been voiced.[11]

History[edit]

Procedural sedation used to be referred to as conscious sedation.

References[edit]

  1. ^ a b c d e f g Walls, Ron M., MD; Hockberger, Robert S., MD; Gausche-Hill, Marianne, MD, FACEP, FAAP, FAEMS (2018). Rosen's Emergency Medicine: Concepts and Clinical Practice. Ninth Edition. Elsevier.
  2. ^ "Procedural Sedation for Cardioversion".
  3. ^ a b c d e f g Stone, C. Keith. "Procedural Sedation and Analgesia." 'CURRENT Diagnosis & Treatment: Emergency Medicine, 8e' Eds. C. Keith Stone, and Roger L. Humphries.New York, NY: McGraw-Hill, , http://accessmedicine.mhmedical.com.ezproxy-v.musc.edu/content.aspx?bookid=2172&sectionid=165058258.
  4. ^ "Continuum of Depth of Sedation; Definition of General Anesthesia and Levels of Sedation/Analgesia". American Society of Anesthesiologists (ASA). 2009.
  5. ^ a b Hohl, CM.; Sadatsafavi, M.; Nosyk, B.; Anis, AH. (January 2008). "Safety and clinical effectiveness of midazolam versus propofol for procedural sedation in the emergency department: a systematic review". Acad Emerg Med. 15 (1): 1–8. doi:10.1111/j.1553-2712.2007.00022.x. PMID 18211306.
  6. ^ a b c d e f Jaap Vuyk, Elske Sitsen and Marije Reekers (2015). Miller's Anesthesia. Elsevier.
  7. ^ Messenger DW, Murray HE, Dungey PE, van Vlymen J, Sivilotti ML (October 2008). "Subdissociative-dose ketamine versus fentanyl for analgesia during propofol procedural sedation: a randomized clinical trial". Acad Emerg Med. 15 (10): 877–86. doi:10.1111/j.1553-2712.2008.00219.x. PMID 18754820.
  8. ^ "BestBets: Does the time of fasting affect complication rates during ketamine sedation".
  9. ^ Berger, Jessica; Koszela, Keri (2018). The Harriet Lane Handbook. Elsevier.
  10. ^ Ip U, Saincher A (January 2000). "Safety of pediatric procedural sedation in a Canadian emergency department". CJEM. 2 (1): 15–20. PMID 17637112.
  11. ^ Krauss B, Green SM (March 2006). "Procedural sedation and analgesia in children". Lancet. 367 (9512): 766–80. doi:10.1016/S0140-6736(06)68230-5. PMID 16517277.

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