The patient population in the electrophysiology (EP) lab presents a unique challenge for anesthesia and conscious sedation providers. EP patients can be categorized into three groups: those who need a cardiac ablation for the treatment of arrhythmias, those who need an EP study to determine if they are a candidate for an ablation or an implanted cardiac device, and those who require cardiac device implantation such as a pacemaker or internal defibrillator (ICD). Aside from the basic anesthesia requirements found in most surgical procedures like amnesia, analgesia and the maintenance of homeostasis, EP cases can present additional challenges such as dealing with hypotension from arrhythmia induction, the development of cardiac tamponade, and effusion during an ablation or device implantation.
In many EP labs, it is standard practice for an electrophysiologist to request anesthesia services for cases that require general anesthesia (e.g., atrial fibrillation ablations) or cases in which deep IV sedation is needed (e.g., supraventricular ablations). Cases such as device implantations and EP studies may receive conscious sedation by a registered nurse (RN) under the supervision of an electrophysiologist.
Patients needing to undergo ablations or device implantations can encounter their own set of issues. These include low cardiac ejection fraction (EF) and/or poor respiratory status, which could make it difficult to achieve adequate sedation levels and maintain a proper level of respiratory and cardiac function. If these issues are identified as too complex for the scope of care of a registered nurse, anesthesia services may be requested. Patients receiving procedures in the EP lab who have comorbidities such as severely low EF, potential airway risks, large body mass indexes, pulmonary hypertension, or other life-threatening issues, are typically identified ahead of time. Once these issues are identified, then anesthesia services may be requested to meet their specific needs.
One way the EP program at the Duke University Medical Center has met the anesthesia and sedation needs of adult EP patients is to utilize a dedicated, full-time anesthesia team. Several years ago, a new staffing plan was developed to improve the safety and quality of care patients receive in the Duke EP lab. The plan utilizes a dedicated team of certified registered nurse anesthetists (CRNAs), supervised by cardiac anesthesiologists and coordinated by the EP CRNA Anesthesia Clinical Team Lead (myself). The Duke Heart Center currently employs eight CRNAs that are supervised by one of the approximately 25 cardiac anesthesiologists on staff with the Duke Department of Anesthesiology’s Cardiac Division. The cardiac anesthesiologists are coordinated by Mihai V. Podgoreanu, MD, Division Chief of Duke Cardiothoracic Anesthesiology, and Madhav Swaminathan, MD, MB BS, Clinical Director of Duke Cardiothoracic Anesthesiology. Together, the Duke MD/CRNA anesthesia team staff cases performed in one of four adult EP labs as well as a TEE/cardioversion treatment room. By utilizing a dedicated EP CRNA team paired with cardiac anesthesiologists, Duke has been able to deliver a consistent level of anesthesia care to EP patients, helping to increase patient safety, satisfaction levels, and case success.
Role of the Dedicated EP Anesthesia Team
The positive outcomes of having anesthesia coverage for all cases in the Duke EP lab (with the exception of tilt table studies) are apparent. The EP CRNAs, working exclusively in the labs under the guidance of cardiac anesthesiologists, are able to mesh with the rest of the EP team, which helps to foster a better team approach to patient care. The EP CRNA group is able to learn the personal preferences of electrophysiologists, which has had a positive effect on EP procedures. The cardiac anesthesiologists, already familiar with the EP cardiac patient population, make a valuable contribution to the EP team as well. The cardiac anesthesiologists not only provide supervision of the EP CRNAs, but also share their cardiac anesthesia knowledge, skills, and professional mentorship with the EP CRNA team.
Prior to the implementation of a dedicated EP MD/CRNA anesthesia team at Duke, several CRNAs were employed to cover anesthesia request cases. At times, additional CRNA coverage was needed, and CRNAs were pulled from the main operating room to help cover EP cases. Even with an adequate orientation, it was difficult for the float CRNA providers to hone their skills enough to meet the unique needs of EP patients, especially during complex cases such as ventricular tachycardia (VT) ablations. This was due in part to infrequent and/or limited exposure to the EP lab environment. The float CRNA staff would often find the EP environment and case details unfamiliar, which decreased patient safety and case success. CRNA providers who were not well trained in EP procedures had an increased chance of missing the early signs of potentially lethal complications such as cardiac effusion or tamponade, or not vigilantly monitoring for rapid esophageal temperature rising during radiofrequency (RF) ablations. Once this was recognized, the Duke Heart Center and anesthesia management set out to find a solution. The plan for a dedicated EP anesthesia team was created and implemented. Having a dedicated EP anesthesia team at Duke allows EP anesthesia providers to better understand the intricacies of cases in the lab and to play a more active role during EP procedures. By discussing real-time events with the electrophysiologists and utilizing EP knowledge, Duke EP anesthesia providers can adjust treatments to tailor their plan to meet case objectives.
Case Objectives and Considerations
A crucial objective during an EP study or ablation is the induction of arrhythmias. It may be necessary for an electrophysiologist to induce a cardiac arrhythmia in order to identify the location of the arrhythmia. Once located, it can be treated through RF, cryotherapy or laser ablation. However, cases such as supraventricular tachycardia (SVT) or VT may be difficult to induce in the clinical environment, especially if anesthetic medications limit heart irritability and subsequent arrhythmia induction. Anesthesia providers can increase the chance of arrhythmia induction while at the same time keeping the patient sedated or anesthetized, by utilizing rapid metabolizing and titratable IV anesthesia drugs such as propofol and/or remifentanil. The use of these medications has proven very successful in the EP setting and is typically given by anesthesia providers using total intravenous anesthesia (TIVA). This is a method of anesthesia in which the sedating and anesthesia medications are given intravenously vs using inhalation anesthetic agents. TIVA is very useful in the EP setting, allowing venous and arterial sheaths to be placed in non-intubated patients (augmented by utilizing local anesthesia). By utilizing TIVA, there can be minimal to no patient movement during sheath placement, lowering the risk of injury to the patient.
The electrophysiologist, after inserting mapping and pacing catheters, will usually attempt to induce an arrhythmia. If the EP team is having difficulty inducing the rhythm, the electrophysiologist may ask to have the sedation level of the patient decreased. When a medication such as propofol is being used for TIVA or monitored anesthesia care (MAC), the level of sedation can be quickly reversed due to the rapid metabolizing mechanisms vs other medications such as midazolam or fentanyl, which can take hours to metabolize and wear off unless a reversal medication is given. Anesthesia providers who understand the potential need to “lighten” the patient at the request of the electrophysiologist will limit the use of medications such as midazolam or fentanyl. These have been known to suppress cardiac irritability and arrhythmia induction (i.e., VT or SVT), which can limit or prevent case success.
Another issue EP anesthesia providers have to contend with during ablations is hypotension from arrhythmia induction. Having an EP anesthesia staff is beneficial because they will be prepared to treat arrhythmia-induced hypotension in a manner that is appropriate for EP patients. If a non-EP anesthesia provider has a “knee-jerk” reaction and treats the arrhythmia-induced hypotension with a large dose of vasoactive medication, and the arrhythmia is quickly broken, there could be an overshooting of the patient’s blood pressure and subsequent marked hypertension. Usually periods of hypotension from rapid pacing or non-sustained arrythmias are brief, and a seasoned EP anesthesia provider knows when to hold off on medication therapy. If an arrhythmia is induced and severe hypotension occurs, the EP anesthesia provider may ask the electrophysiologist to have the patient paced or DC cardioverted out of the arrhythmia, especially if a near pulseless state occurs. At times, arrhythmias that are induced produce lowered blood pressures, and the electrophysiologist and anesthesia provider should decide whether it is possible for the blood pressure to be supported by medications such as phenylephrine, epinephrine or vasopressin. If the patient’s blood pressure can be stabilized while the arrhythmia is sustained, then there is a greater chance that the electrophysiologist can map and/or ablate the arrhythmia. The reaction to arrhythmia-induced hypotension in the EP lab should vary greatly from the reaction in a standard operating room, where hypotension is treated quickly and aggressively with fluids and vasoactive medications, since hypotension can be the result of surgical bleeding. If an arrhythmia-induced hypotension is treated with fluid boluses in the EP lab, the patient is at greater risk of developing fluid overload or pulmonary edema, especially in EP patients with a history of congestive or right-sided heart failure.
Another increased risk related to hypotension in EP lab patients is the detection of cardiac effusion or tamponade during EP procedures. Providers familiar with EP cases are aware of this risk, and keep in mind that if they are treating hypotension during a case, they may be masking a developing tamponade or effusion. Providers who are unfamiliar with the EP setting might continue to give vasoactive medications or fluids which could help stabilize an effusion/tamponade situation temporarily until an inevitable critical event occurs from the underlying problem. If an EP anesthesia provider suspects that there could be an effusion or tamponade, then communication with the electrophysiologist can be done earlier in the case, and appropriate diagnosis and treatments can be made. Since early detection and treatment is key in treating life-threatening effusion or tamponade events, having properly trained anesthesia staff is imperative for patient survival of critical events in the EP lab.
An additional issue that can occur from not utilizing a dedicated anesthesia team involves complications that can arise from improper esophageal temperature monitoring during RF ablations. Anesthesia providers at Duke are tasked to monitor esophageal temperature rises during RF ablation through the use of an esophageal temperature probe. As temperatures rise during burning, providers notify the electrophysiologist by calling out temp increments of 0.1 above baseline. By knowing the temperature status of the esophagus, electrophysiologists have a better idea when to turn off the RF or laser ablator to prevent esophageal rupture or tissue damage, which can lead to the development of atrial-esophageal fistula after RF ablation. Anesthesia staff that have been involved in ablation cases know that esophageal temperatures can rise very quickly. If an anesthesia provider is not cognizant of the dangers from improper temperature monitoring during ablating, then the EP patient is placed at risk of developing a lethal complication.
A dedicated EP anesthesia team will also have a better understanding of the use of muscle relaxants (e.g., for phrenic nerve testing), IV fluid maintenance plans, biplane movable X-ray machines, and/or magnetic interference from mapping systems. Providers who are exclusively in the EP lab are familiar with the uniqueness of the lab and equipment used daily. A provider who only occasionally provides care in the EP lab may find these issues to be troublesome and distracting, drawing important attention away from the patient.
Adequate Sedation Levels
A specific group of patients who can benefit from a dedicated anesthesia team in the EP lab are those having cardiac devices surgically implanted. At many EP centers, it is common for RNs to provide sedation for device implant cases. Most institutions limit the use of IV anesthesia medications such as propofol to trained anesthesia personnel; this limits the range of medications nurses can use for sedation. The IV medications fentanyl and midazolam are commonly used by RNs for sedation during these procedures. RNs must be vigilant when administering these medications in order to not render the patient apneic or drop blood pressures to critically low values. Since drug administration amounts may be limited due to comorbidities of patients, it can be difficult to reach adequate sedation levels. Patients who are undergoing surgery with inadequate sedation levels are at greater risk of experiencing pain and negative intra-operative memories. Also, patients who may be experiencing inadequate sedation may have an increased amount of movement on the procedure bed, which increases difficulties for the surgeon and intra-operative complications such as pneumothorax or vessel/cardiac perforation.
At Duke, EP patients who are having a cardiac device implanted and are receiving care from EP anesthesia providers typically experience deeper levels of sedation compared to conscious sedation methods provided by a registered nurse. Duke EP anesthesia providers are able to achieve deep levels of sedation for device cases by utilizing TIVA methods, which are similar to the methods used to provide anesthesia for ablations. By rendering the patient unconscious, patients at Duke typically do not remember the injection of local anesthetic at the surgical site or the placement of the device. Cases utilizing propofol can be timed in such a manner that the patient is unconscious and remains asleep until the surgical dressing is applied. Many times the use of narcotics is reduced, if not eliminated completely, with the use of propofol. This makes it a superior sedation medication for device implantation. If dosed and timed correctly, patients who have received propofol IV sedation can wake up more quickly and be less sedated than a patient who may have had narcotics or benzodiazepines to keep them sedated during a case. Patients who have returned to the Duke EP lab to have a device implanted and who have had a history of device implantation with a non-propofol sedation method, typically report a higher level of satisfaction after experiencing propofol-induced unconsciousness during their case. Many post-procedure Duke Heart Center patients have reported greater satisfaction from a deeper level of sedation with the use of propofol as compared to the conscious sedation method that utilizes narcotics and/or benzodiazepines. Positive experiences such as being more comfortable, having less intra-operative awareness, and experiencing reduced post-procedure nausea and a quicker mental recovery have helped to raise overall patient satisfaction scores at the Duke Heart Center.
There are multiple ways to provide sedation and anesthesia to patients receiving procedures in the EP lab. All EP patients, whether they are having a device implanted or an EP study or ablation, need to have adequate levels of sedation or anesthesia for their procedure in a manner that does not sacrifice their safety or decrease case success. Duke Heart Center has experienced positive results by utilizing a dedicated anesthesia team to meet EP patient care needs. Not only have Duke EP patients expressed a greater satisfaction level related to the dedicated anesthesia team method, but Duke electrophysiologists and other EP staff have expressed positive feedback as well. Specifically, they report an optimized performance level of the EP MD/CRNAs in the lab. Dedicated anesthesia providers working in the EP lab feel a higher level of commitment, responsibility, and a vested ownership related to their role in the lab. EP anesthesia staff members also have the chance to integrate tightly with other EP staff, allowing them to improve patient care, safety, and workflow in the EP lab.
Finding ways to improve the safety and care of EP patients should be a priority for all EP healthcare providers. Having a dedicated anesthesia team such as the one at Duke University is one way to help increase patient safety and case success, as well as to increase EP lab proficiency and lab utilization. By implementing the dedicated anesthesia team model, Duke Heart Center is helping to meet the needs of its patients seeking treatment. The achievements gained from utilizing this staffing model at the Duke EP lab can be a positive example for other EP centers looking to improve patient care and to address the unique needs of future EP patients.
Disclosure: The author has no conflicts of interest to report regarding the article herein.
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