Ramsin Benyamin MD Millennium Pain Center, Bloomington, IL, USA During the past couple of decades, the utilization of interventional pain procedures in chronic pain patients has seen significant growth [1]. Many spine treatments have shifted from more invasive surgeries to minimally invasive, mostly percutaneous, and image-guided procedures. This shift has also translated to a higher utilization of less invasive anesthesia modality such as intravenous (IV) sedation, and Monitored Anesthesia Care (MAC). Under the appropriate circumstances, properly managed sedation can improve patient comfort and facilitate performance of interventional procedures. In spite of the inherent hazards, particularly with deep sedation and general anesthesia, the risk vs. benefit ratio for specific patients should be assessed thoroughly prior to offering sedation. Availability of short-acting and safer anesthetics resulting in faster recovery times are some of the driving forces behind patients’ desires and expectations to utilize anesthesia services. Consequently, greater utilization has the potential for an increased number of reported adverse events. Most of the epidemiologic data on the incidence of adverse events during anesthesia are provided mainly by the publications from the American Society of Anesthesiologists’ (ASA) Closed Claims Project, which started in 2019, and is operating under the auspices of the Anesthesia Quality Institute. Unfortunately, the ASA Closed Claims process cannot provide the total number of adverse events or procedures performed. Lawsuits form a small proportion of adverse events, with a bias toward severe outcomes and substandard care, therefore ASA Closed Claims studies only analyze severe adverse events. Bhananker et al. [2] reported specifically on the incidence of severe adverse events following MAC. The severity of injury for MAC claims was comparable to general anesthesia claims, with 41% of the claims being for death or permanent brain damage. Respiratory depression, as a result of oversedation, was the most common mechanism of injury. Nearly 75% of the patients who experienced injury related to sedation received a combination of two or more drugs, either a benzodiazepine and an opioid or propofol plus others causing additive or even synergistic effects on depression of ventilatory response to carbon dioxide. Half of the patients who were oversedated were elderly or had an ASA physical status of III–IV and hence were probably more susceptible to the respiratory depressant effects of the sedative–analgesic–hypnotic drugs used. Titration to effect by very slow administration of sedatives and opioids may be important to avoid respiratory depression in this patient population. Nearly half of the injuries related to sedation in this review were judged as preventable by the use of additional or better monitoring. In the authors’ opinion, lack of vigilance contributed to damage in many of the events. The percentage of severe adverse events associated with MAC in the Closed Claims database has gradually increased from approximately 5% during 1990 to 1999 to 10% during 2000 to 2009 [3]. Patient death is the most common severe adverse event in the MAC claims, and is significantly more common than mortality associated with general or regional anesthesia. Most fatal incidents resulted from inadequate oxygenation and/or ventilation in non-operating room areas with suboptimal monitoring facilities and the inability to prevent and appropriately manage oversedation. More specific to pain management, Pollack et al. [4] analyzed the trends in pain medicine claims from 1980 to 2012 in the Anesthesia Closed Claims Project database. Malpractice claims for pain medicine increased from 3% of total malpractice claims in the 1980–1989 time period to 18% of anesthesia claims in 2000–2012. Non-neurolytic cervical injections increased to 27% of pain claims in 2000–2012. Claims related to cervical procedures were out of proportion to the frequency with which they were performed. Pain medicine claims have increased over time as has the level of severity. Authors concluded these liability findings suggest that pain specialists should aggressively continue the search for safer and more effective therapies. The role of anesthesia in causing severe complications during cervical procedures was explored by Rathmel et al. [5]. Their review of closed claims revealed that cervical procedures represented 22% of chronic pain management malpractice claims between 2005 and 2008. Injuries were commonly permanent and disabling compared to other chronic pain claims, with 59% experiencing spinal cord damage, and 31% resulting from direct needle trauma. General anesthesia or sedation was used in 67% of cervical procedures associated with spinal cord injury but, only in 19% of cases not associated with spinal cord injury. Of the patients who underwent cervical procedures and had spinal cord injuries, 25% were nonresponsive during the procedure compared with 5% of the patients who underwent cervical procedures and did not have spinal cord injuries. Among those with spinal cord injury, 91% had epidurals with 65% using the interlaminar route and, ironically, no contrast was used in 43% of cases. The Second ASRA Practice Advisory on Neurologic Complications Associated with Regional Anesthesia and Pain Medicine issued an Executive Summary in 2015 determining the warning signs such as paresthesia or pain on injection of local anesthetic to be inconsistent with herald needle contact with the spinal cord [6]. Nevertheless, some patients do report warning signs of needle-to-neuraxis proximity and therefore, general anesthesia or deep sedation removes any ability for the patient to recognize and report warning signs. They suggested that neuraxial regional anesthesia or interventional pain medicine procedures should rarely be performed in adult patients whose sensorium is compromised by general anesthesia or deep sedation. The American Society of Interventional Pain Physicians (ASIPP) published their guidelines on sedation and fasting for patients undergoing interventional pain procedures in 2019 [7]. They adopted the ASA guidelines on the use of sedation and opined that “under appropriate circumstances, properly managed sedation can improve patient comfort and facilitate performance of interventional procedures. However, given the inherent hazards, particularly with deep sedation and general anesthesia, the risk vs. benefit ratio for specific patients should be assessed”. They emphasized that, due to the nature of chronic pain and anxiety, many patients undergoing interventional techniques may require mild-to-moderate sedation. At the same time, they warned that deep sedation and/or general anesthesia for most interventional procedures is considered as unsafe, since the patient cannot communicate acute changes in symptoms. Routine use of sedation for diagnostic facet injections was discouraged by the multispecialty, international working group in their consensus practice guidelines published in 2020 [8]. When using sedation, they suggested that patients should be educated on the increased risk of a false-positive block, and the lowest doses of short-acting sedatives, ideally without opioids, should be given. In order to assist clinicians and patients to make decisions based on benefits of moderate procedural sedation and decreasing the risk of adverse outcomes, a multidisciplinary task force of physicians from several medical and dental specialty organizations in 2018, published guidelines specifically addressing moderate procedural sedation provided by any medical specialty in any location [9]. The specialty societies included the American Society of Anesthesiologists Task Force on Moderate Procedural Sedation and Analgesia, the American Association of Oral and Maxillofacial Surgeons, the American College of Radiology, the American Dental Association, the American Society of Dentist Anesthesiologists, and the Society of Interventional Radiology. These comprehensive guidelines focused specifically on moderate sedation and included new recommendations to reduce risk of complications by emphasizing: The ASA has defined four levels of sedation, where level 4 corresponds to general anesthesia (Table 8.1). Table 8.1 Four levels of sedation.
8
Complications of Sedation in Painful Procedures
Introduction
Stages/Levels of Sedation
Continuum of Depth of Sedation, Definition of General Anesthesia, and Levels of Sedation/Analgesia
Minimal Sedation (Anxiolysis)
Moderate Sedation/Analgesia (Conscious Sedation)
Deep Sedation/Analgesia
General Anesthesia
Responsiveness
Normal response to verbal stimulation
Purposeful* response to verbal or tactile stimulation
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