Noncardiac implantable electronic devices for the treatment of medically refractory pathologies have grown in popularity. Examples of noncardiac implantable electronic devices include spinal cord stimulators, deep brain stimulators, vagal nerve stimulators, sacral nerve stimulators, phrenic nerve stimulators, gastric pacemakers, implantable pulmonary artery pressure monitors, intrathecal pump delivery systems, bone-anchored hearing aids, cochlear implants, and bone stimulators. With their increasing popularity, these devices must be managed in the perioperative period by the anesthesiologist. In contrast to their cardiac counterparts (for instance, pacemakers and/or defibrillators),1 there are neither practice advisories nor expert consensus statements that address the perioperative management of these devices. There is also little literature2,3 to guide clinical management.
We present our experience with the perioperative management of a patient who had 3 implantable electronic devices and an intrathecal morphine pump.
Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review.
A 69-year-old woman with a medical history significant for breast cancer, chronic lumbar and abdominal pain, gastroparesis, and urinary incontinence presented for bilateral breast reconstruction with latissimus dorsi flaps. Her surgical history included the implantation a spinal cord stimulator and an intrathecal morphine pump for medically refractory abdominal pain, a sacral nerve stimulator for urinary incontinence, and a gastric pacemaker for severe gastroparesis (Fig. 1). All devices had been evaluated within the previous year and were deemed to be functioning appropriately. The devices provided symptomatic relief from her baseline conditions, allowing activities of daily living with no complications.
The patient’s history and medical images were discussed at length with the surgical team to minimize electromagnetic interference (EMI) and avoid mechanical damage to implanted components during surgical dissection. With an external programming device, the patient decreased the spinal cord stimulator and sacral nerve stimulator’s power to the lowest possible settings and subsequently switched them off. The intrathecal pump was left functional per recommendations from the chronic pain medicine consultants. The gastric pacemaker lacked patient-controlled external programmability and a medical device representative was unavailable preoperatively. After a discussion of the risks and benefits, the patient decided to proceed with the surgery with a functional device in place.
The patient underwent uneventful general anesthesia with endotracheal intubation. The procedure was performed using bipolar cautery, significantly prolonging its duration. After successful emergence from anesthesia and tracheal extubation, the patient had an uneventful recovery. The function of the spinal cord stimulator and sacral nerve stimulator were reinitiated in the postanesthesia care unit. The patient was transferred to the ward. Within the next 24 hours, all devices were interrogated by industry representatives and found to be working properly. After all devices were returned to the preoperative setting, she was discharged home.
There is increased interest in the use of noncardiac implantable electronic devices for the management of many medically refractory conditions. Indications, locations, and placement techniques vary among individual devices; however, commonly all implantable electronic devices have 3 components. First, these devices have a battery-powered, externally programmable (by either the patient or the physician) pulse generator. Second, stimulators have lead electrodes, which come into direct contact with the target tissue through insulated cables connecting the pulse generator to the electrodes.
Although these devices are popular and ubiquitous, there are neither guidelines nor expert consensus statements for the perioperative management of noncardiac implantable electronic devices. The literature addressing their perioperative management is scarce.2,3
Initial programming of implantable electronic devices is relatively standard. Typically, the initial settings are programmed by the implanting physician with the help of the industry representative after implantation. Programming variables include rate, amplitude, and lead electrode positioning (setting). For spinal cord stimulators, several features are available. The device has on/off functions. The amplitude or intensity of stimulation and the stimulating lead electrode are also modifiable to maximize the patient’s therapeutic benefit and comfort. The device may be programmed to be fully and individually patient controlled or the functions can be set as groups of settings from which the patient may choose. For sacral nerve stimulators, only the device on/off and the amplitude/intensity of stimulation settings can be modified. Gastric pacemakers currently lack any patient-controlled functions.
For the management of this challenging case, from the available literature, we extrapolated recommendations from the expert consensus on the management of cardiac implantable electronic devices1 as well as other strategies to reduce the risk.2,3 These led us to several conclusions about the management of such patients.
First, preoperative evaluation should focus on the type of implantable device and its location, its indication, date of implantation, and potential complications associated with the device. It is important to ascertain the date of the last interrogation, the ease and method of programmability of the device, and the severity of symptoms when the device is turned off.2,4
Second, the perioperative care of the patient with implantable devices (both cardiac and noncardiac) should be individualized and focused on the scheduled surgical procedure.1
Third, the surgical team and perioperative nursing staff should discuss any safety concerns and possible surgical instrument interactions with the device. The location and lead trajectory of the device should be addressed in detail with the surgical team. A plan that minimizes risk of damage to, or malfunction of, the device should be developed. Finally, as a general principle, the presence of an industry representative during the perioperative period is very helpful.2 However, it is inappropriate to have industry-employed professionals (industry representatives) independently develop prescriptive recommendations or independent postoperative care of the patient with implantable devices1 independent from the responsible physicians.
Manufacturers warn that EMI from routinely used electrosurgical equipment may result in damage to device components, including temporary changes in the neuromodulating output, reprogramming, or temporary suppression.3 In addition, current flow through the lead and electrode system can cause catastrophic tissue injury.5,6 For the reasons listed, it is often recommended that the device be switched off preoperatively.2,3
Special precautions need to be in place when the use of diathermy is contemplated. Diathermy is different from electrosurgery, in that diathermy generates heat for therapeutic purposes by the use of high-frequency electric current (for instance, diathermy is used by chiropractors or physical therapists to treat tissue injury or can be used to destroy neoplasms, warts, or to cauterize bleeding blood vessels). Most commonly, diathermy uses microwave (typically 915 MHz or 2.45 GHz), short-wave (range, 1–100 MHz), or ultrasound energy, and this type of electrosurgery can destroy unintended tissues even if the device is turned off.2 For this reason, diathermy should be used cautiously in patients with implantable electronic devices.
Electrosurgery, also called electrocautery, refers to a high-frequency electrical current that is delivered to tissues through a handheld electrode.7 Two modes of current delivery can be used: monopolar and bipolar. Monopolar refers to a current that is delivered through a single high-density electrode to the surgical site. Subsequently, the current disperses through the patient’s body to ultimately converge at a large surface area, low-current density return pad, completing the circuit. Although this pad is sometimes referred to as a grounding pad, the term is a misnomer because it is strictly the return electrode and does not complete a circuit to ground. EMI from monopolar electrosurgery is the most common source of device malfunction during surgery.1 Pacemaker complications include oversensing and becoming inhibited during exposure to EMI. Defibrillators and pacemakers may falsely detect arrhythmias. Devices may be reset by EMI. Some pulse generators may be damaged by electrosurgery.1 If monopolar electrosurgery cannot be avoided, the return (grounding) pad should be placed such that the electrical current (traveling between the monopolar lead and return pad) does not cross components of the device,1,2 and the length of individual monopolar electrosurgery bursts should be limited to 5 seconds or less.1
In bipolar electrosurgery, a current travels between 2 closely adjacent electrodes (the cautery instrument tips) with selective involvement of the tissues located between the 2 electrodes. The flow of electrical energy is concentrated at the surgical site minimizing EMI within the rest of the patient’s body.3,7 Bipolar electrosurgery does not cause EMI unless it is applied directly to the implantable device.1 In patients with cardiovascular implantable devices, when the risk of EMI is low (for instance, during the use of bipolar electrosurgery or when the use of monopolar electrosurgery is limited to below the umbilicus), generally no reprogramming is needed.1 Noncardiac implantable electronic devices are similar to their cardiac counterparts, and strategies to minimize the risk of electrosurgery include avoiding its use altogether or using the bipolar rather than monopolar mode.
In addition to complications that may occur with electrosurgery, other procedures may interrupt normal function of cardiac implantable devices. Cardioversion may result in resetting of the device. Radiofrequency ablation may act similarly to monopolar electrosurgery, but the risk is even greater because the duration of current exposure is prolonged.1 Therapeutic radiation may reset the device. Electroconvulsive therapy may cause EMI during the delivery of the stimulus. Transcutaneous electrical nerve stimulation units can result in EMI and interference with the implantable device.1
In our patient, after discussing the intended intraoperative management with the surgical team, we decided that the safest course would be both to program the devices to the lowest output and then turn off and avoid the use of monopolar electrosurgery altogether. Because the use of monopolar electrosurgery was not deemed critical by our surgical colleagues, and our experience with managing multiple implantable devices was limited, we opted to err on the side of safety.
Postoperatively, all patients with implantable devices should be evaluated for potential damage in and around the location of the device, recognizing that damage to the device lead–tissue interface from external current is unlikely.1 In light of the paucity of data and consensus recommendations regarding postoperative evaluation of noncardiac implantable electronic devices, we suggest that the device undergo interrogation by qualified personnel as soon as feasible, ideally, before the patient’s discharge from the hospital to ensure appropriate device function and resumption of therapeutic efficacy. For cardiac implantable electronic devices, there are specific procedures and recommendations on postoperative evaluation and range from no evaluation beyond routine to evaluation before discharge.1
Because of the growing popularity of implantable medical devices, it is imperative that anesthesiologists be familiar with these devices, their indications, functionality, potential interactions with equipment in the operating room, and the strategies to minimize their risk perioperatively. To this end, we believe that a specific practice advisory for the perioperative management of noncardiac implantable electronic devices should be developed.
Dr. Sorin J. Brull is the Section Editor for Patient Safety for the Journal. This manuscript was handled by Dr. Steven L. Shafer, Editor-in-Chief, and Dr. Brull was not involved in any way with the editorial process or decision.
1. Crossley GH, Poole JE, Rozner MA, Asirvatham SJ, Cheng A, Chung MK, Ferguson TB Jr, Gallagher JD, Gold MR, Hoyt RH, Irefin S, Kusumoto FM, Moorman LP, Thompson A. The Heart Rhythm Society (HRS)/American Society of Anesthesiologists (ASA) Expert Consensus Statement on the perioperative management of patients with implantable defibrillators, pacemakers and arrhythmia monitors: facilities and patient management: executive summary this document was developed as a joint project with the American Society of Anesthesiologists (ASA), and in collaboration with the American Heart Association (AHA), and the Society of Thoracic Surgeons (STS). Heart Rhythm. 2011;8:e1–18
2. Venkatraghavan L, Chinnapa V, Peng P, Brull R. Non-cardiac implantable electrical devices: brief review and implications for anesthesiologists. Can J Anaesth. 2009;56:320–6
3. Voutsalath MA, Bichakjian CK, Pelosi F, Blum D, Johnson TM, Farrehi PM. Electrosurgery and implantable electronic devices: review and implications for office-based procedures. Dermatol Surg. 2011;37:889–99
4. Association of periOperative Registered Nurses. . AORN guidance statement: care of the perioperative patient with an implanted electronic device. Association of periOperative Registered Nurses. AORN J. 2005;82:74–82
5. Dommerholt J, Issa T. DBS and diathermy interaction induces severe CNS damage. Neurology. 2001;57:2324–5
6. Nutt JG, Anderson VC, Peacock JH, Hammerstad JP, Burchiel KJ. DBS and diathermy interaction induces severe CNS damage. Neurology. 2001;56:1384–6
7. LeVasseur JG, Kennard CD, Finley EM, Muse RK. Dermatologic electrosurgery in patients with implantable cardioverter-defibrillators and pacemakers. Dermatol Surg. 1998;24:233–40