Conscious Sedation for Cardioversion
Cardioversion is often used to terminate cardiac arrhythmias, such as persistent atrial fibrillation. During cardioversion, patients are often given intravenous medication to cause sedation. Although the procedure can be an effective treatment it is quite painful, which is why sedation is required. Sedation prevents patients from experiencing the discomfort of the procedure; it also decreases the stress response and the subsequent surge of catecholamines associated with this.
Conscious sedation, as the term implies, is sedation without rendering the patient completely unconscious. The key to sedation during cardioversion is to administer enough medication to prevent recall of the procedure, but not so much that cardiorespiratory function is compromised.
Medication administered to provide sedation does not have an analgesic effect. In many cases, a combination of medications may be used during conscious sedation for cardioversion, such as a short-acting sedative or muscle relaxant and an analgesic.
Ideally, the patient should be able to maintain airway control and oxygenation with minimal support during and after sedation for cardioversion. However, complications are always possible and patients react to medication differently. Medical personnel must always be prepared and ready to act in the event that complications develop.
Before a Conscious Sedation
Before a conscious sedation for cardioversion occurs, patient selection should be carefully considered. Patients who have had a previous bad reaction to sedation medications or who have difficult airways may not be good candidates for conscious sedation. In addition, patients who have underlying medical conditions which may affect how they respond to sedation may not be ideal candidates. If a patient appears to be high risk for conscious sedation, elective intubation and anesthesia may be an alternative.
Even if a patient appears to be an appropriate candidate for conscious sedation, depressed respiratory drive can develop. Before conscious sedation occurs, it is essential to ensure that emergency resuscitation equipment is set up and adequate staff are present at the bedside to provide care if needed.
Equipment should be set up and ready to go in case the patient has an adverse reaction to the medication. A bag-mask device should be attached to an oxygen flow meter in the event the patient needs to be manually ventilated.
An oral airway device is also needed to prevent airway obstruction. In some instances as a patient becomes sedated, their tongue may fall to the back of their throat and obstruct their airway. A suction device should also be ready to use in case the patient has secretions blocking their airway, vomits or needs to be intubated.
Follow your hospital policies regarding CO2 monitoring. Exhaled end-tidal carbon dioxide monitoring can be an effective tool to monitor respiratory status. The American Society of Anesthesiologists currently recommends exhaled end-tidal carbon dioxide monitoring during moderate or deep sedation.
Keep in mind that pulse oximetry monitors alone may not be adequate to monitor a patient’s respiratory function. For instance, patients who are administered supplemental oxygen may be able to maintain adequate oxygenation for a period of time, but they may still be hypoventilating. This is where an end-tidal carbon dioxide monitor can be useful.
During the Procedure
Sufficient personnel should be at the beside, which includes someone dedicated to monitoring the patient’s airway and respiratory status. After the sedation is administered, the patient’s respiratory rate, oxygen level and carbon dioxide level should be monitored.
Close monitoring is also essential to ensure the patient can maintain a patent airway. If sedation appears to have caused an airway obstruction, it may be necessary to perform a maneuver to open the patient’s airway, such as a head tilt- chin lift. Be sure you adhere to safety guidelines and refrain from touching the patient during the actual cardioversion (shock).
After a Conscious Sedation for a Cardioversion
If an adverse reaction occurs during or after the procedure, such as desaturation, apnea or cardiac instability, implement the appropriate interventions, such as manually ventilating the patient.
Usually sedation administered during cardioversion wears off quickly, but this can vary. Patients should be monitored closely until the effects of the sedation have worn off. Ensure the patient’s oxygen saturation is back to baseline, CO2 levels are within normal range, and the patient can maintain a patent airway. Observing and talking to the patient after the cardioversion is helpful to determine alertness.
Harrison, S. National Institute of Health. Cardioversion and the Use of Sedation. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1768594/ Accessed September 2014.
Farzan, Sattar, MD, FACP, FCCP A Concise Handbook of Respiratory Diseases. Prentice Hall 1997. Accessed September 2014