June 2000
Volume 64 |
Number 6
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| Liability Profile
of Ambulatory Anesthesia |
Karen L. Posner, Ph.D.,
Health Systems Analyst and Project Manager
ASA Closed Claims Project
With the growth in ambulatory surgery and anesthesia in the United
States comes a parallel growth in liability for the anesthesiologist
providing ambulatory anesthesia services. The U.S. government
estimates that about half of all anesthesia procedures are conducted
on an ambulatory basis.1 The good
news for anesthesiologists practicing in an outpatient setting
is that fewer than half of all closed anesthesia malpractice claims
arise from procedures conducted on an ambulatory basis [Figure
1].
The Closed Claims Project database consists of standardized summary
data on anesthesia malpractice claims collected from 35 professional
liability carriers throughout the United States.2
These carriers insure approximately half of the practicing anesthesiologists
in the United States. The Closed Claims Project is conducted by
the ASA Committee on Professional Liability and has been ongoing
since 1985. There are currently 4,459 claims in the Closed Claims
Project database. Claims for damage to teeth or dentures are excluded.
The following data are derived from the 552 outpatient and 1,874
inpatient claims for adverse events from 1980 or later in the
Closed Claims Project database.
While ambulatory anesthesia malpractice claims represent only
23 percent of the 2,426 claims analyzed, the proportion of claims
arising from ambulatory settings has been increasing. Ambulatory
anesthesia claims represented 20 percent of claims from 1985-89
and 26 percent of claims from 1990-95 (p < 0.05). Claims for
the late 1990s are not yet available because it takes nearly five
years between the occurrence of an adverse event, claim closure
and subsequent data collection for inclusion in the Closed Claims
Project database.
Patients and Procedures
Not unexpectedly, patients filing claims for ambulatory anesthesia
were generally younger and healthier than inpatients [Table
1]. Most outpatient claims were filed by ASA I-II patients
with a mean age of 40 years compared to a mean age of 43 years
for inpatients (p <0.05). This difference in age probably reflects
the slightly higher percentage of pediatric patients in the ambulatory
group as well as the lower percentage of older patients. Most
claims in both groups were filed by females.
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Closed Claims
Outpatient Plaintiffs
1980-1995
(n = 552)
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Closed Claims
Inpatient Plaintiffs
1980-1999
(n = 1874)
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U.S. Ambulatory
Surgery Patients
19961
(n = 21,000,000)
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| % Total |
23 % |
77 % |
52 % |
| % Female |
61 % |
60 % |
56 % |
| Mean Age |
40* |
43 |
NA |
| % < 15 yrs |
11 % ** |
8 % |
8 % |
| % > 65 yrs |
11 % ** |
16 % |
34 % |
| ASA 1-2 |
83 % ** |
61 % |
NA |
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1 National Center for Health Statistics
* p < 0.05 compared to mean inpatient plaintiff
age ** p < 0.01 compared to proportion of inpatient
claims
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The age profile of ambulatory anesthesia patients filing claims
differs from the age profile of patients with ambulatory surgery
visits in 1996 as reported by the U.S. government.1
The proportion of pediatric patients (< 15 years) is similar
in both groups, but the proportion of older patients is quite
different [Table 1]. Patients 65 or older
account for 34 percent of 1996 ambulatory surgery visits in the
United States but only 11 percent of closed claims.1
Although the ambulatory surgery visit data (1996) are more recent
than the Closed Claims Project data (1980-95), even a comparison
to the more recent closed claims from 1990 or later shows a similar
trend, with only 13 percent of 1990-95 closed ambulatory anesthesia
claims involving patients 65 or older. We do not know if this
difference between claims and visits reflects the patient safety
profile of ambulatory anesthesia or if it simply reflects differences
in tendencies to file claims in different age groups. This is
an example of the difficulty of attempting to generalize about
anesthesia injury from closed claims. Since not all patients who
are injured file claims, and some patients who are not injured
do file claims, closed claims data can only describe liability
and is not a valid source for information on the spectrum of anesthesia
injury in general.
Figure 2: Most Common Surgical Procedures Associated with
Ambulatory Anesthesia Claims
As expected, the surgical procedures associated
with ambulatory anesthesia claims differed from inpatient claims
[Figure 2]. This may account for some of the differences in complications,
as the most common procedures in ambulatory anesthesia claims
were orthopedic procedures on the extremities, procedures on the
face, head or neck (including dental and ENT), ophthalmic surgery
and gynecological procedures. These procedures combined represented
two-thirds of ambulatory anesthesia claims (66 percent) and were
more than twice as common in outpatient claims compared to inpatient
claims (27 percent).
Claims associated with ambulatory anesthesia more commonly involved
regional anesthesia or monitored anesthesia care (34 percent)
than inpatient claims (23 percent, p <0.05). General anesthesia
was implicated in 65 percent of outpatient claims and 73 percent
of inpatient claims.
Damaging Events
The "damaging event" is the particular aspect of anesthesia
management that led to patient injury. Among inpatient claims,
the most common damaging events involved management of the respiratory
system (26 percent). Examples include difficult intubation, inadequate
oxygenation or ventilation, and airway obstruction. Among ambulatory
anesthesia claims, 21 percent involved respiratory system events.
Cardiovascular system events accounted for 9 percent of outpatient
claims, while equipment problems accounted for another 10 percent.
These percentages are similar to inpatient claims. However, miscellaneous
events unrelated to the respiratory or cardiovascular systems
or equipment comprised 26 percent of outpatient claims but only
15 percent of inpatient claims. The most common complaints were
related to regional block placement (8 percent of outpatient claims),
including block needle trauma, high block or dural puncture. In
3 percent of outpatient claims, the patient moved or coughed during
anesthesia, usually during ophthalmic surgery, resulting in eye
injury. In 2 percent of outpatient claims, surgery was conducted
on the wrong side or wrong patient, or the wrong surgical procedure
was performed.
Figure 3: Most Common Complications in Ambulatory Anesthesia
Claims
Most Common Complications
The injuries in ambulatory anesthesia claims tended
to be less severe than the injuries in inpatient claims. Most
ambulatory anesthesia claims were for temporary or nondisabling
injuries (62 percent compared to 48 percent inpatients, p ¾0.05).
Death and brain damage were less common among outpatients than
inpatients (p ¾0.05) [Figure 3]. Eye injuries and pneumothorax
were more common among outpatients (p ¾0.05). The most common
nonfatal injuries in outpatient claims were nerve injury (16 percent),
eye injury (10 percent), airway injury (8 percent), brain damage
(7 percent), pneumothorax (6 percent), emotional distress (5 percent),
burns (4 percent), headache (4 percent) and back pain (3 percent).
Litigation and Payments
Ambulatory anesthesia claims were more likely to be resolved
without a lawsuit than inpatient claims (21 percent ambulatory
claims with no lawsuit filed versus 16 percent inpatient, p ¾0.05).
Payment rates were about the same for ambulatory and inpatient
anesthesia claims, which may reflect similarities in appropriateness
of anesthesia care between the two groups: Half received anesthesia
care that met standards, and only 38 percent received care that
was clearly substandard.
While payment rates were similar, payment amounts differed between
outpatient and inpatient claims. In general, payments to outpatients
were lower than payments to inpatients (median $75,000 versus
$140,000, p ¾0.01). This is not surprising because it has
been found that payment amounts correlate with severity of injury,
and outpatient claims involved less severe injuries than inpatient
claims.3 While payments in outpatient
anesthesia claims were relatively low, the highest payment was
over $14 million, and there were a total of 24 outpatient claims
(4 percent overall) with payments greater than $1 million.
Conclusion
Analysis of closed claims suggests that ambulatory anesthesia
represents an increasing area of liability risk for the anesthesiologist.
The liability profile of ambulatory anesthesia may simply reflect
the increasing proportion of procedures conducted on an outpatient
basis as well as the type of patients and procedures in this setting
rather than any particular patient safety issues.
References:
1. Hall MJ, Lawrence L. Ambulatory Surgery
in the United States, 1996. Advance Data from Vital and Health
Statistics. No. 300. Hyattsville, Maryland: National Center for
Health Statistics; 1998.
2. Cheney FW. The American Society of Anesthesiologists
Closed Claims Project. What have we learned, how has it affected
practice, and how will it affect practice in the future? Anesthesiology.
1999; 91:552-556.
3. Cheney FW, Posner K, Caplan RA, Ward J. Standard
of care and anesthesia liability. JAMA. 1989; 261:1599-1603.
Karen L. Posner, Ph.D., is Research Associate
Professor, Departments of Anesthesiology and Anthropology (Adjunct),
University of Washington, Seattle, Washington.
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