September 2000

SAMBA ANNUAL MEETING REPORT

By Kathryn McGoldrick, M.D.

The 15^th Annual Meeting of the Society for Ambulatory Anesthesia was held from May 4-7, 2000 in Washington, D.C., with the program attracting more than 500 registrants. The general sessions covered a vast array of timely topics including cost containment, office-based anesthesia, strategies for accessing medical information on the Internet, alternative medicine, the ASA Closed Claims Project's relevance for the ambulatory anesthesiologist, anesthetic outcomes and their implications for healthcare policy, case discussions, and management of postoperative complications and dilemmas. The seven scheduled workshops offered practical advice on ACLS, ambulatory perioperative pain management, contemporary Medicare compliance issues, new airway management devices, negotiating managed care contracts, outpatient regional anesthesia, and prevention/management of malpractice suits. Obviously, temporal and spatial constraints do not permit in-depth coverage of all these topics, and we have chosen to focus on lessons learned from the Closed Claims Project and management of postoperative complications and dilemmas.

I. ASA Closed Claims Project: Lessons for the Ambulatory Anesthesiologist

The ASA Closed Claims Project is a structured evaluation of adverse anesthetic outcomes obtained from the closed claims files of 35 professional liability insurance companies in the United States that insure approximately 50% of U.S. anesthesiologists. As such, it provides a snapshot of anesthesia liability, but it is not a comprehensive picture of all anesthetic injury. The Closed Claims Project has been an ongoing undertaking of the ASA Committee on Professional Liability since 1985, involving adverse outcomes from as long ago as 1961. Currently, 4,459 claims are on the database, with 2,426 representing cases from 1980 onwards. (All dental claims were excluded from the database.) Limitations of closed claims analysis have been widely discussed and include lack of data concerning the total population at risk for injury (i.e., the denominator) and nonrandom, retrospective data collection (some of which was obtained from involved parties). Nonetheless, the strengths of the Closed Claims Project are several and include the considerable value the analyses offer in highlighting specific, descriptive patterns of anesthetic mishaps.

    Karen Posner, Ph.D., from the University of Washington in Seattle spoke about "The Liability Profile of Ambulatory Anesthesia."¹ She pointed out that outpatients represent an increasing area of liability risk for anesthesiologists, with few claims occurring before 1985. (Claims for outpatient pain management were excluded from the ambulatory anesthesia claims.) The good news for ambulatory anesthesiologists, however, is that considerably less than half of all anesthesia malpractice claims arise from procedures conducted on an ambulatory basis, despite the fact that approximately 70% of all surgeries in the U.S. involve outpatients. Approximately 57% of all outpatient claims resulted in payment to the plaintiff, despite the fact that half of the claims involved care that was deemed appropriate by the expert reviewers. Dr. Posner pointed out that, although payment rates were similar when one compares inpatients with outpatients, the median payment to outpatients was lower ($75,000 vs. $140,000), reflecting the difference in the typical severity of injury in the two venues. Eye injury was especially common, and complications of regional anesthesia were also relatively frequent. In addition to ophthalmic procedures, gynecologic, ENT, dental, cosmetic, and orthopedic surgical procedures also accounted for many of the ambulatory anesthesia claims. Litigation associated with ambulatory anesthesia more commonly involved regional anesthesia or monitored anesthesia care than inpatient claims. Whereas 73% of inpatient claims involved general anesthesia, in only 65% of outpatient claims was general anesthesia involved. Interestingly, most of the outpatient plaintiffs were female and relatively healthy, and the majority of outpatient claims were for temporary or nondisabling injury.

    Karen B. Domino, M.D., M.P.H., also from the University of Washington, spoke on "Issues of Awareness,² Airway Trauma,³ and Monitored Anesthesia Care."⁴ Awareness accounted for 79 or 1.9% of claims in the ASA Closed Claims database, a similar proportion in the database to burns, aspiration pneumonia, and myocardial infarction. Eighteen claims were for awake paralysis, that is, the inadvertent paralysis of an awake patient, and 61 involved claims for recall under general anesthesia. Most awareness claims involved women (77%) younger than 60 years (89%), ASA physical status I and II (68%), who underwent elective surgery (87%). Most claims (94%) for awake paralysis involved substandard care in terms of improper labeling and administration of drugs, whereas care was substandard in only 43% of the claims of recall during general anesthesia. A predisposing factor for awareness may be small doses of (intravenous) general anesthetic agents. Indeed, many investigators report prevention of conscious recall by administration of relatively small concentrations of volatile anesthetics.^5-7 Interestingly, the classic clues (tachycardia and hypertension) for light anesthesia were absent in most cases. Patient movement was observed in only one patient, probably because most patients received muscle relaxants. (The role of neurophysiologic monitoring in the prevention of intraoperative awareness is not discussed in the Closed Claims manuscript dealing with intraoperative awareness.) It is unclear why female gender is associated with a three times higher rate of recall claims than other types of claims. Perhaps this reflects a gender-related increased vulnerability to intraoperative recall or an increased propensity for women to file claims for recall or other temporary injuries. Interestingly, gender-related differences in the requirement (greater in women) for intravenous anesthetics have recently been reported.^8,9

    Patients who have experienced awareness during anesthesia typically describe auditory perceptions, the sensation of paralysis, anxiety, helplessness, and panic. Apparently, the sensation of pain is experienced less frequently. As many as 70% of patients who had intraoperative awareness experience unwanted after effects, including sleep disturbances, dreams and nightmares, and flashbacks and anxiety during the day.¹⁰ A minority of patients develop post-traumatic stress disorders with repetitive nightmares, anxiety, irritability, and preoccupation with death.

    The liability risk of intraoperative recall is uncertain. It may be that the relatively low median payment ($18,000) for intraoperative awareness may deter plaintiffs' attorneys from pursuing these cases. However, given the copious amount of dramatic publicity given recently to the problem of intraoperative awareness, perhaps it is not unlikely that increased public concern about this issue may increase the financial liability risk.

    Dr. Domino then moved on to a discussion of litigation involving airway injury, a relatively frequent (6%) event in claims from 1961 to 1996. Indeed, airway injury ranked fourth behind death (32%), spinal cord or peripheral nerve damage (16%), and brain damage (15%). Thirty-nine percent of airway claims involved difficult intubation and the standard of care was deemed to be appropriate in 79% of claims. Of note is the fact that while most pharyngoesophageal injuries were associated with difficult intubation, 80% of laryngeal injuries were associated with nondifficult or routine intubation and were thought to be the result of endotracheal tube movement and pressure necrosis. Pharyngoesophageal injuries, in contrast, were more severe than other airway injuries, with 19% being fatal. Unfortunately, prompt diagnosis of pharyngoesophageal perforation is extremely difficult. Therefore, the Closed Claims investigators recommend that after a difficult intubation patients and the surgeon should be warned to watch for symptoms of retropharyngeal abscess or mediastinitis. These warning signs include severe sore throat as well as deep cervical or severe chest pain, especially if accompanied by fever.

    During the 1990s monitored anesthesia care (MAC) claims became more common, accounting for 6% of cases. The MAC patients tended to be older, sicker (ASA physical status III to V) outpatients (65%). Injuries during MAC were severe, with death (39%) and brain damage (15%) common. Eye injuries, especially those due to patient movement, were common. Payments to patients who sustained MAC-related injuries were high, similar to payments that involved general anesthesia. The mechanism of MAC-related injury was often respiratory (25%) or cardiovascular (14%). It is troubling that litigation from adverse outcomes during MAC increased during the 1990s, despite the use of pulse oximetry and other respiratory monitoring.

    Frederick W. Cheney, M.D., Professor and Chairman of Anesthesiology at the University of Washington, discussed "ASA Closed Claims Project: What Have We Learned about Nerve Injury and Cardiac Arrest?". For the current analysis, the term "nerve damage" was used to describe injuries in which there were clinical, anatomic, or laboratory findings consistent with damage to discrete elements of the spinal cord or peripheral nervous system. (Brain damage and vocal cord palsies were excluded.) Ulnar neuropathies were the most frequent (28%) nerve injury claims, followed by injuries to the brachial plexus (20%), lumbosacral nerve root (16%), and spinal cord (13%). However, data accumulated to date from the 1990s indicate spinal cord injury as the leading cause of claims for nerve damage (27%) that occurred during this decade. General anesthesia was the most common anesthetic technique associated with ulnar neuropathies and brachial plexus injuries, while lumbosacral nerve root and spinal cord injuries were more apt to be associated with regional anesthesia. (To date, the data on nerve injuries have not been subdivided according to inpatient or outpatient status.)

    Most spinal cord injuries in the database resulted in paraplegia or quadriplegia. The mechanism of injury was established in 48% of claims, and these most commonly were epidural hematoma, chemical injury, anterior spinal artery syndrome, and meningitis. Major factors associated with spinal cord injury were blocks for chronic pain management and systemic anticoagulation in the presence of neuraxial block. In 10 claim files it was explicitly stated that delayed diagnosis of the epidural hematoma was a major factor in the resultant injury. The lesson to be learned is that if neuraxial block is performed in the presence of systemic heparinization, the patient should be monitored meticulously and any unexpected motor or sensory changes should be strongly considered as potential signs of an epidural hematoma and an aggressive diagnostic work-up should be conducted. Because the most recent claims in the database at the time of this review are from 1992, there were no claims for epidural hematoma occurring in the presence of low-molecular-weight heparin, since the drug was not approved for general use by the Food and Drug Administration until 1993.

    In contrast to the spinal cord injury subset, it is remarkable how rarely a definite mechanism of injury was clearly established in the peripheral nerve injury groups despite extensive medical and legal investigation. The mechanism was particularly elusive in claims involving ulnar nerve injury, where symptoms are often delayed, typically occurring 2 to 7 days postoperatively.¹¹ A striking male preponderance has been reported, perhaps owing to the more prominent tubercle of the coronoid process in men, as well as the thicker retinaculum in the cubital tunnel of males. Moreover, in 27% of ulnar nerve injuries, extra padding over the elbows was explicitly documented. Clearly, factors other than the standard of care influenced medicolegal outcome, because payment was made in 47% of the ulnar nerve injury claims in which care was deemed appropriate by expert anesthesiologists who were not involved in the litigation.

    Dr. Cheney pointed out that in the overall database of 4,459 claims there were 69 intraoperative cardiac arrests in patients having ambulatory procedures. The vast majority of these patients were young and relatively healthy. The anesthetic technique employed was general in 78%, MAC in 12%, and regional in 10% of the arrests. The first publication (based on 900 claims) form the ASA Closed Claims Project database in 1988 reported sudden cardiac arrest in 14 healthy patients having spinal anesthesia.¹² Six patients died, and of the eight survivors seven had serious neurologic damage. That initial report emphasized the suddenness of the bradycardia and asystole that can develop with spinal anesthesia despite seemingly satisfactory vigilance and resuscitation efforts by the anesthesia providers. In the current database of 4,459 claims there are 170 claims for injury secondary to cardiac arrest during spinal/epidural anesthesia (which includes the original 14 cases). Again, the patients were predominantly young and healthy, with high severity of injury that involved death or brain damage in nearly 90% of the claims. The need for vigilance must be underscored, along with the necessity to move quickly and aggressively with epinephrine administration in the setting of profound sympathetic blockade.

    A separate workshop on malpractice issues was moderated by Kathryn E. McGoldrick, M.D., Professor of Anesthesiology and Medical Director of Ambulatory Anesthesia at Yale. Panelists were Frederick W. Ernst, M.D., a Medicolegal Advisor from Dothan, Alabama; Martin Bogetz, M.D., Professor of Clinical Anesthesia and Medical Director of Same Day Surgery at the University of California, San Francisco; Richard A. Wiklund, M.D., Director of Pre-Admission Testing at Massachusetts General Hospital, Boston; and Scott T. Kragie, Esq., a partner at Squire, Sanders & Dempsey in Washington, D.C., who is a legal advisor to the ASA. The group emphasized the importance of vigilance, competence, and meticulous documentation. Moreover, they also underscored the need to establish excellent rapport with patients and their families and to answer questions honestly and openly. It was pointed out, however, that our medicolegal system is flawed, and that damage awards tend to correlate with and reflect the severity of injury sustained rather than the appropriateness of care delivered.



II.  Postoperative Complications and Dilemmas

    Terri G. Monk, M.D., Professor of Anesthesiology at The University of Florida in Gainesville, presented a fascinating lecture on postoperative cognitive dysfunction, a problem not uncommon in elderly patients [see the audio interview with Dr. Monk.]. The clinical features of this disorder range from mild forgetfulness to permanent cognitive impairment resulting in loss of independence. In one study, 35% of elderly patients undergoing surgery for femoral neck fractures developed postoperative confusion in the first week after surgery, and the incidence of the problem was the same regardless of whether regional or general anesthesia was administered.¹³ Pre-existing mental depression and a history of use of anticholinergic medications may have some predictive value.

    Dr. Monk discussed in detail a recent, multinational, prospective study of postoperative cognitive decline following noncardiac surgery. In this study, Müller and colleagues¹⁴ evaluated cognitive function in patients aged 60 years or older after major abdominal and orthopedic surgery. These investigators found that approximately 25% of the patients had measurable cognitive dysfunction a week after their surgery and 10% had cognitive changes three months postoperatively. This finding contrasted with a 3% incidence of cognitive deterioration in healthy control subjects in the same age range who did not undergo anesthesia and surgery. Interestingly, despite extensive monitoring, neither hypoxemia nor hypotension correlated with the occurrence of prolonged cognitive dysfunction. The identified risk factors for early postoperative cognitive dysfunction were increasing age and duration of anesthesia, low education level, a need for a second operation, postoperative infection, and respiratory complications. The only risk factor for late postoperative cognitive dysfunction was age.

    Dr. Monk believes that the type of surgical procedure may play a role. Elderly people, for example, frequently require orthopedic surgery where emboli may be released when the tourniquet is deflated, or bone fragments may cause problems after they gain access to the circulation. Perhaps the geriatric central nervous system is different and many elderly patients may already have had small infarcts that may predispose them to developing postoperative cognitive deficits.

    In summary, it is currently agreed that postoperative cognitive dysfunction is a real entity, but it is still unclear which patient populations are most vulnerable and the causative factors for this important problem. Hopefully, future studies will lead to a clearer definition of the incidence, mechanisms, and prevention of postoperative cognitive dysfunction. Girish P. Joshi, M.D., Associate Professor of Anesthesiology and Pain Management at the University of Texas Southwestern Medial Center in Dallas, discussed "Fast Tracking: Lessons Learned". Dr. Joshi emphasized that the availability of newer, shorter-acting drugs has enabled patients to be awake and alert soon after the completion of surgery. Thus, there is a trend towards transferring patients directly from the operating room to the phase II recovery area (i.e. bypassing the PACU). This paradigm is referred to as fast-tracking in ambulatory surgery.

    The selection of anesthetic technique can be a major determinant of the speed of recovery. Indeed, a study by Apfelbaum and colleagues¹⁵ reported that 80% of patients receiving MAC bypassed the PACU, compared with 14-42% of patients receiving general anesthesia. Moreover, prevention of such postoperative complications as postoperative nausea and vomiting, respiratory difficulties, or inadequate analgesia can facilitate recovery in ambulatory patients. Obviously, the best way to accomplish these objectives is with a clear and coordinated perioperative plan, implemented as clinical pathways. Finally, Dr. Joshi underscored his belief that our conventional definition of fast-tracking is too narrow because it ignores the importance of the entire or overall postoperative recovery period. The process of fast-tracking should be extended to the phase II unit stay (enabling earlier discharge home) as well as to facilitate an earlier return to routine daily activities.

REFERENCES

1. Posner K. Liability profile of ambulatory anesthesia. ASA Newsletter 64(6):10-12, 2000
2. Domino KB, Posner KL, Caplan RA, Cheney FW. Awareness during anesthesia: A closed claims analysis. Anesthesiology 90:1053-1061, 1999
3. Domino KB, Posner KL, Caplan RA, Cheney FW. Airway injury during anesthesia: A closed claims analysis. Anesthesiology 91:1703-1711, 1999
4. Domino KB. Trends in anesthesia litigation in the 1990s: Monitored anesthesia care claims. ASA Newsletter 61:15-17, 1997
5. Harris TJB, Brice DD, Hetherington RR, Utting JE. Dreaming associated with anaesthesia: the influence of morphine premedication and two volatile adjuvants. Br J Anaesth 43:172-178, 1971
6. Warren TM, Datta S, Ostheimer GW, Naulty JS, Weiss JB, Morrison JA. Comparison of the maternal and neonatal effects of halothane, enflurane, and isoflurane for cesarean delivery. Anesth Analg 62:516-520, 1983
7. Newton DEF, Thornton C, Konieczko K, et al. Levels of consciousness in volunteers breathing sub-MAC concentrations of isoflurane. Br J Anaesth 65:609-615, 1990
8. Glass P, Sebel PS, Rosow, C, Payne F, Embree P, Sigl J. Do women wake up faster than men? (abstract) Anesthesiology 85:A343, 1996
9. Drover DR, Lemmens HJM. Population pharmacodynamics and pharmacokinetics of remifentanil as a supplement to nitrous oxide anesthesia for elective abdominal surgery. Anesthesiology 89:869-877, 1998
10. Moerman N, Bonke, B, Oosting J. Awareness and recall during general anesthesia. Facts and feeling. Anesthesiology 79:454-464, 1993
11. Warner MA, Warner DO, Matsumoto JY, Harper CM, Schroeder DR, Maxson PM. Ulnar neuropathy in surgical patients. Anesthesiology 90:54-59, 1999
12. Caplan RA, Ward RJ, Posner KL, Cheney FW. Unexpected cardiac arrest during spinal anesthesia: A closed claims analysis of predisposing factors. Anesthesiology 68:5-11, 1988
13. Berggren D, Gustafson Y, Eriksson B, et al. Postoperative confusion after anesthesia in elderly patients with femoral neck fractures. Anesth Analg 66:497-504, 1987
14. Müller JT, Cluitmans P, Rasmussen LS et al. Long-term postoperative cognitive dysfunction in the elderly: ISPOCD1 study. Lancet 351:857-861, 1998
15. Apfelbaum JL, Grasela TH, Walawander CA and the SAFE Study Team. Bypassing the PACU - a new paradigm in ambulatory surgery (abstract). Anesthesiology 87:A32, 1997