Some background information for those unfamiliar with the ASA closed claims project (this background information is taken from the closed claim website http://depts.washington.edu/asaccp/ASA/index.shtml ): Since 1985 the ASA has sponsored this project. At the time the project was initiated, professional liability insurance was expensive for anesthesiologists and in some states difficult to obtain. The intention of the Closed Claims Project was to identify causes of loss, improve patient safety, and thereby relieve the insurance problem for anesthesiologists. The project consists of an in-depth investigation of 7328 closed insurance claims resulting from anesthetic mishaps. Data is gathered in the form of detailed case summaries collected by ASA member anesthesiologists from insurance company claim files. Claims for dental injury, a very common, well understood, and in most cases minor injury, are excluded. Claims in which the basic sequence of events and/or nature of the injury cannot be reconstructed from the information in the insurance files are also been excluded. This results in most cases being collected from mishaps resulting in lawsuits, as files in these cases contain the most extensive information. Cases are collected from throughout the United States on a continuous basis. The database consists of standardized summaries of each case, including patient information (e.g. age, physical status), surgical procedure and positioning, anesthetic evaluation and technique, events leading to the injury or claim, type and severity of injury, outcome of litigation, and physician evaluations of potential for prevention and appropriateness of anesthesia care. The database also includes a brief narrative summary of each claim, describing the sequence of events and adding any pertinent information not contained in the standardized data collection form.
In my opinion the closed claims project provides a unique resource of intensively studied case experiences in which there was an outcome that was not satisfactory to the patient or their family. It does not allow the calculation of incidence as the denominator is not known. Because of the length of time from law suit to settlement, the data in the closed claims project tends to be old. Thus new areas of risk or trends in settlement costs are, in my opinion, difficult to determine from this data.
The ASA closed claims analysis of awareness during anesthesia was published in 1999 and included claims for adverse outcomes that occurred between 1961 and 1995. A total of 4183 claims were in the database. Seventy nine claims were for awareness with a greater proportion occurring in the 1990s compared to earlier decades. The proportion of claims in the database was similar to burns, aspiration pneumonia and myocardial infarction. Compared to other claims awareness more often involved women, patients younger than 60 years of age, and elective surgery. The severity of injury for awareness claims was lower than for the other claims. Eighteen of the claims were for awake paralysis and 61 claims were for recall during general anesthesia.
Claims for awake paralysis were related to intravenous infusion errors or syringe swaps. Succinylcholine drips accounted for 10 of the 18 claims (unlabelled, mislabeled, failure to check the label). The period of risk was preinduction or during induction when a muscle relaxant was given instead of a sedative or hypnotic.
The highest frequency of recall during general anesthesia was during the maintenance phase (49 of 61 claims). Recollection included recollection of conversation, feeling surgery without pain, pain, paralysis, tracheal intubation, and severe panic. Eighty four percent sustained temporary emotional distress; 10% developed posttraumatic stress disorders. Recurrent nightmares were described in 16% of claims and psychotherapy was described in 13%.
Factors associated with recall during general anesthesia included: nitrous – narcotic relaxant technique without volatile anesthetic (11 of 61 claims), hypotension requiring discontinuation of the anesthetic agent (11 instances), inadequate dose of anesthetic for no obvious reason (8), difficult intubation (5), failure to adjust anesthetic dose for morbid obesity (8), vaporizer leak (5) and failure to turn on the vaporizer (3). In 10 cases no obvious factor could be determined. The classic cues for light anesthesia were absent in most cases. Five factors were significantly associated with claims for recall compared to other general anesthesia claims: no volatile anesthetic agent, female gender, obstetric or gynecologic procedure, intraoperative opioid, and intraoperative muscle relaxant. After adjusting for risk factors and application of multiple logistic analyses – female gender and anesthetic techniques using intra operative opioid and muscle relaxants without a volatile anesthetic increased the relative frequency of claims of recall. OB/Gyn procedures were not an independent risk factor. (From Domino KB et al: Awareness during anesthesia: A closed claims analysis. Anesthesiology 1999;90:1053-1061.)
DSS comments: The separation of “awake paralysis” from “recall” is not done in most subsequent studies. Notice the frequency of a drug error with respect to the occurrence of awake paralysis. Changes in practice (decreased use of succinylcholine infusions) may decrease this incidence. However bags of non depolarizing muscle relaxants for infusion present the same potential risk unless clearly labeled and kept away from other intravenous solutions until the time of use. Several of the instances of awake paralysis occurred because of a syringe swap or mislabeled syringe. An argument might be made to keep syringes containing muscle relaxant separate from antibiotics, anxiolytics, narcotics and anesthesia induction drugs. Finally using nitrous oxide without a volatile agent was associated with a large number of instances of recall. Fortunately that practice has almost disappeared (at least at Hospital of the University of Pennsylvania).
David S. Smith, M.D., Ph.D.