Abstract

• Claims related to surgical implantation of devices involved infection, inadequate pain relief, trauma to the cord or cauda equina, and retained catheter fragments • Claims related to implanted drug delivery system maintenance tended to involve more serious outcomes associated with medication administration errors and failure to recognize granuloma formation ABSTRACT Background: Due to an increase in implantable device-related anesthesia pain medicine claims, the authors investigated anesthesia liability associated with these devices. Methods: After institutional review board approval, the authors identified 148 pain medicine device claims from 1990 or later in the Anesthesia Closed Claims Project Database. Device-related damaging events included medication administration events, infections, hematomas, retained catheter fragments, cerebrospinal fluid leaks, cord or cauda equina trauma, device placed at wrong level, stimulator incorrectly programmed, delay in recognition of granuloma formation, and other issues. Results: The most common devices were implantable drug delivery systems (IDDS; 64%) and spinal cord stimulators (29%). Device-related care consisted of surgical device procedures (n = 107) and IDDS maintenance (n = 41). Severity of injury was greater in IDDS maintenance claims (56% death or severe permanent injury) than in surgical device procedures (26%, P < 0.001). Death and brain damage in IDDS maintenance claims resulted from medication administration errors (n = 13; 32%); spinal cord injury resulted from delayed recognition of granuloma formation (n = 9; 22%). The most common damaging events for surgical device procedures were infections, inadequate pain relief, cord trauma, retained catheter fragments, and subcutaneous hygroma. Care was more commonly assessed as less than appropriate (78%) and payments more common (63%) in IDDS maintenance than in surgical device procedure claims (P < 0.001). Conclusions: Half of IDDS maintenance claims were associated with death or permanent severe injury, most commonly from medication errors or failure to recognize progressive neurologic deterioration. Practitioners implanting or managing devices for chronic pain should exercise caution in these areas to minimize patient harm. (Anesthesiology 2016; 124:1384-93) Preliminary findings were published for the American Society of Anesthesiologists annual meeting in San Diego, California, October 24-28, 2015 (Pollack KA, Stephens L, Fitzgibbon DR, Posner K, Rathmell JP, Michna E, Domino KB: Injury and liability associated with implantable devices for chronic pain. Abstract A1006). There are a number of potential safety hazards associated with IDDS, including medication errors, 8 Turner et al. Due to the increase in implantable device-related anesthesia pain medicine claims from 3% in the 1980s to 16% of pain medicine claims in the 2000s, Materials and Methods The Anesthesia Closed Claims Project database is a structured evaluation of adverse anesthetic outcomes obtained from the closed malpractice claims files of U.S. professional liability insurance companies. The data collection process has previously been described in detail. Definition of Variables All pain medicine claims in the Anesthesia Closed Claims Project database were classified by the type of pain medicine care provided by the anesthesiologist, including device-related care, consultations, medication management, nonlytic blocks and injections, lytic chemical procedures, lytic thermal procedures, acupuncture, discography, intradiscal electrothermal therapy, and other invasive procedures. Device-related care was initially categorized by type of device: implantable drug delivery systems (IDDS), tunneled catheters, SCS, and peripheral nerve stimulators, and by type of care provided: implant, replace, remove, or maintain the device. After initial analyses, the damaging events and outcomes associated with implanting, replacing, and removing all four types of devices were found to be similar to each other, and consequently, they were grouped together as "surgical device procedures." Damaging events were defined as the mechanism by which a complication or injury occurred or allegedly occurred. Device-related damaging events were grouped into the following categories: medication administration events, device-related infections, device-related hematomas, retained catheter fragments, CSF leaks, needle, catheter, or lead trauma to the cord or cauda equina, device placed at wrong level, stimulator incorrectly programmed, delay in recognition of granuloma formation (soft tissue masses resulting from an inflammatory reaction at the level of the catheter tip), failure to diagnose presenting condition or cause for new symptoms (excludes granuloma formation), patient did not cooperate in his/her own care (taking additional opioids not prescribed by the plaintiff anesthesiologist), inadequate pain relief or pain made worse, and other issues. Medication administration events were further subclassified as programming errors, side portfill or pocket-fill of medication (accidental injection during a refill procedure of all or some of the prescribed drug into the patient's subcutaneous tissue, which includes the pump pocket, instead of into the pump), inappropriately high doses of medication on an outpatient basis, wrong drug administered, adverse drug reactions, equipment malfunction, and other medication issues. Inadequate pain relief events consisted of claims where no relief was ever experienced after insertion of the device, claims where the insertion of the device immediately increased the level of pain, and claims where there was an initial improvement in pain, but the pain returned at a later time. The severity of injury in each claim was assigned using the National Association of Insurance Commissioners' 10-point scale, which ranges from 0 (no apparent injury) to 9 (death). Appropriateness of care was assessed by the on-site reviewer based on reasonable and prudent criteria for anesthesia practice at the time of the event. Standard of care was assessed as appropriate, less than appropriate, or impossible to judge. The reliability of these evaluations has been judged as acceptable. Statistical Analysis Device-related claims were compared to other pain medicine claims by chi-square analysis, Fisher exact test, Student's t test, and Mann-Whitney U test using P < 0.05 for statistical significance. Claims for IDDS maintenance and surgical device procedures were also compared by the same statistical tests. All payments made to the plaintiff were extracted from the database and adjusted to 2014 dollar amounts with the Consumer Price Index. 15 Because payment amounts were not normally distributed, median and interquartile ranges were reported as descriptive statistics. Claims with no payment were excluded from calculation of median and interquartile range. All statistical analyses were conducted using SPSS 19.0.0 for Windows (IBM Corporation, USA). Results Device-related versus Other Pain Medicine Claims Most (97%, n = 144) device-related claims involved management of nonmalignant chronic pain. Two devices were for management of cancer-related pain and two for spasticity. Injuries in device-related claims occurred between 1990 and 2011. Implantable device-related claims (n = 148) were similar to other pain medicine claims (n = 822) with a few exceptions: device-related claims were more likely to occur on an inpatient basis (40%, n = 53, vs. 7%, n = 54, P < 0.001; table 1), and patients in device-related claims had more medical issues than patients in other pain medicine claims (46%, n = 60, vs. 29%, n = 191, American Society of Anesthesiologists 3 to 5, P < 0.001; table 1). The injuries that resulted from device-related claims were more likely to be temporary and/or minor than the injuries that resulted from other pain medicine claims (66%, n = 97, vs. 54%, n = 439, P = 0.02; table 1). Serious injuries occurred with death in 9% (n = 14) of device-related claims and permanent disabling injury in 25% (n = 37). Standard of care and payments did not differ between device-related and other pain medicine claims The most common devices in the device-related claims were IDDS (n = 94, 64%) and SCS (n = 43, 29%). Devicerelated care provided by anesthesiologists consisted of surgical device procedures (n = 107, 72%) and maintenance of IDDS (n = 41, 28%; table 2). There were no claims for maintenance of SCS, peripheral nerve stimulators, or tunneled neuraxial catheters. IDDS Maintenance versus Surgical Device Procedure Claims The severity of patient injury was greater in claims related to IDDS maintenance compared to claims related to surgical device procedures ( Damaging events differed between IDDS maintenance and surgical device procedure claims. While 61% (n = 25) of IDDS maintenance claims were associated with medication management issues, only 7% (n = 8) of surgical device procedure claims had events related to medication administration Specific Damaging Events and Outcomes in Devicerelated Claims Medication administration damaging events (n = 33) were associated with 64% of all device-related death or severe permanent brain damage claims ( For all device-related claims, the most common reasons for severe permanent injury to the spinal cord or cauda equina (n = 27) were delay in recognition of granuloma formation (33%, n = 9), needle trauma to the spinal cord or caudal equina (26%, n = 7), and epidural hematoma (11%, n = 3; Implantable Devices for Chronic Pain Procedure-related infections associated with surgical procedures occurred in 25 of 107 claims-related surgical device procedures (23%; table 3). Seven of the 25 infections were associated with retained foreign bodies, e.g., sponges and leads (table 4). The injuries were either temporary or minor for all but 3 of the 25 procedure-related infections. The three claims with permanent severe injuries resulted in one claim each for finger amputation, severe brain damage, and death. In nine claims, a CSF leak occurred resulting in formation of a lumbar subcutaneous hygroma Of the 17 claims for inadequate pain relief or an increase in pain after the device was implanted, 11 were associated with SCS (table 4). Three of the 10 SCS never provided any relief of pain, and 1 was associated with an immediate increase in pain. For 7 of the 11 stimulator claims, the patient initially reported pain relief for a period of time before the spinal cord stimulator failed to provide relief. In three of those claims, the leads had migrated; in one claim, the patient experienced a fall just before the failure; in three claims, there was no obvious reason why the relief had subsided. Of note, in four device-related claims, the patient did not cooperate in his or her own care by taking opioids and other PAIN MEDICINE medications not prescribed by the defendant anesthesiologist Discussion This is the first study of liability associated with implantable devices for treatment of chronic pain. Severe injuries were more commonly associated with IDDS maintenance than with surgical device procedures (66 vs. 26%; Severe injuries with IDDS maintenance were associated with medication administration errors and failure to recognize granuloma formation. Severe injuries from surgical device procedures involved needle trauma to the spinal cord or cauda equina or surgical site infections. Implantable Devices for Chronic Pain Management Implantable devices such as SCS and IDDS for chronic pain management represented 93% of device-related claims in the Anesthesia Closed Claims Project database. These devices require surgical procedures for implantation/replacement or removal, regular monitoring of use, replacement over time, and refilling of pumps at regular intervals. 8 Fifty-nine percent of all reported events resulted in patient death; no deaths were assessed as the direct result of device failure or infusion therapy failure. However, the Food 4 Device-related hematomas (n = 5) 1 (2) 0 (0) 0 (0) 4 (9) Patient did not cooperate in his/her care (n = 4) 0 (0) 1 (2) 2 (20) 1 (2) Stimulator incorrectly programmed (n = 2) 2 (4) Other (n = 8)# 0 (0) 4 (10) 0 (0) 4 (9) *Devices removed consisted of implantable drug delivery systems (IDDS), spinal cord stimulators, and tunneled catheters. †Stimulators were for spinal cord and peripheral nerves. ‡Other medication administration issues consisted of one claim each for equipment malfunction, failure to purge a pump, wrong volume administered, and patient sent home with pump known to be nonfunctioning. §Other patient condition issues after implantation or replacement of IDDS or catheters consisted of one claim each for postprocedure addiction, cardiovascular accident, and unexplained seizures. Other patient condition issues after implantation or replacement of stimulators consisted of one claim each for areflexic bladder, hypotension and hypoxemia, progression of degenerative disc disease, and unexplained respiratory event. ║An IDDS pump stopped providing relief after catheter migration. Three spinal cord stimulators stopped providing relief after lead migration, one after patient fell, and three had no obvious reason why they stopped providing pain relief. #Other damaging events for IDDS maintenance consisted of one claim each for cerebrospinal fluid (CSF) leak, patient's care not transferred to new physician, insurance issues, and one unknown damaging event. Other damaging events for implant/replace stimulators consisted of one claim each for patient fell off procedure table, stimulator manufacturer sent wrong part, surgical technique of another physician working with the anesthesiologist, and anesthesiologist supervising sedation and implanting pump at the same time. Downloaded from anesthesiology. 22 IDDS Medication Administration Events Opioid overdose in patients with IDDS can occur for various reasons including pocket fills, 5,23 changes in intrathecal opioid medication, 24 programming errors, 6 flushing the line accidentally with morphine rather than saline after catheter placement, Outpatient IDDS management typically involves simultaneous medication prescription, dispensing, and administration in one step by a single provider, potentially increasing the probability of error. A mechanism to prevent such errors might include two person checks for appropriateness of dosing, programming, and refill procedures with detailed accounting to the patient and the patient's family of potential adverse events and the changes made during the visit. At each refill, patients should be instructed about possible symptoms of a medication error and to seek immediate assistance should any of these symptoms occur. 26 Potentially catastrophic pocket fills occur during IDDS refill if the needle is not inserted through the refill port septum until it has reached the metal bottom of the refill port or the needle is moved outside the refill port. This can result in placement of a large amount of drug outside the pump (in subcutaneous tissue) where it can be rapidly absorbed into the systemic circulation, leading to serious morbidity/ mortality. Symptoms usually occur immediately or within several hours. To prevent pocket fills, the leading IDDS manufacturer produced guidelines for critical actions to be taken during the pump refill procedure. 27 Accidental side port injections can result in direct injection of highly concentrated opioids or other drugs into the CSF with life-threatening consequences. Our study identified two deaths from side port injections. Both occurred before 2004 and were likely related to older pump refill or side port template design that allowed for potential side port injection during refill. Voluntary manufacturer withdrawal of these older devices in 2007 and device redesign appear to have addressed the side port injection problem. Delay in Recognition of Granuloma Formation Delays in recognition of granuloma formation with IDDS were associated with severe permanent injury to the spinal cord or cauda equina in our claim series ( 30-32 Administration of high concentrations or high doses of opioids has been associated with formation of granulomas, 33 with some authors recommending maximum doses of intrathecal morphine at 10 mg/day and concentration of 15 mg/ml. The time required for human granuloma development is uncertain, and times reported vary from 0.5 to 72 months with an average of 24 months until clinical symptoms are identified. Asymptomatic lesions may exist for years before signs or symptoms appear. 29,40 Complications Associated with Device-related Surgical Procedures In our analysis, surgical procedures for devices involved 72% of all claims (n = 107) with temporary or minor complications in 74%. These findings appear consistent with other reports 9,41,42 noting that major complications were rare and minor complications were associated with SCS during placement or removal and superficial infections. PAIN MEDICINE There are reports of traumatic syrinx formation due to spinal cord penetration by the intrathecal catheter during placement 26 Neurologic injury from catheter/lead placement is rare and can occur directly from needle or catheter/lead trauma during insertion or from epidural hematoma or infection. 41 Insertion of intrathecal needles or catheters above L2 increases the risk of spinal cord injury. 45 Placing the intrathecal catheter under fluoroscopic guidance is standard for positioning the tip at the desired vertebral level. Fluoroscopy using multiple planes, e.g., anteroposterior and lateral images, has been recommended as a means to improve the safety of spinal injections. 46,47 Use of the anteroposterior view during initial needle placement allows selection of a vertebral interspace below L2 to avoid entering the thecal sac above the termination of the conus medullaris where direct trauma to the cord may be more likely; this view also allows the practitioner to keep the needle directed toward the midline, avoiding potential injury to the spinal nerves. Use of the lateral view established the depth of needle advancement and can be used to position the catheter tip at the desired vertebral level. 46,47 Multiple-plane imaging was rarely used in claims with spinal cord trauma in our series. Device-related Infections Bolash et al. 51 Study Limitations The limitations of closed claims analysis have been previously described, including selection bias, nonrandom retrospective data collection, and possible geographic imbalance in data collection. 11,12 Data collected by anesthesiologist-reviewers are limited to information gathered for claims resolution. Lawsuits form a small proportion of adverse events, with a bias toward severe outcomes and substandard care. The database lacks a denominator of procedures for estimating rates of complications for the various procedures. Despite these limitations, the database provides detailed information on rare adverse events and outcomes that are otherwise difficult to study prospectively. Conclusions Serious outcomes including death or permanent brain damage resulted from medication administration errors, primarily during maintenance of IDDS. Permanent neuraxial injuries were primarily caused by trauma during device placement and failure to recognize granuloma formation during IDDS maintenance. Clinicians involved with implantation and ongoing care of patients receiving these therapies require a high level of expertise. Morbidity and mortality can be minimized using optimal surgical technique, establishing protocols for refilling and reprogramming, and appropriate patient follow-up with rapid recognition of evolving complications and implementation of appropriate treatment. Acknowledgments The authors acknowledge the closed claims reviewers from the American Society of Anesthesiologists and participation of the following liability insurance companies who have given permission to be acknowledged: Anesthesia Service Medical Group, Inc., San Diego, California; COPIC Insur- The Doctors' Company, Napa, California; The University of Texas System, Austin, Texas; Utah Medical Insurance Association, Salt Lake City, Utah. Supported in part by the American Society of Anesthesiologists (ASA), Schaumburg, Illinois, and the Anesthesia Quality Institute (AQI), Schaumburg, Illinois. All opinions expressed are those of the authors and do not reflect the policy of the ASA or AQI. Competing Interests The authors declare no competing interests.