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June 1997
Volume 61 |
Number 6
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| Anesthesia Patient
Safety and Professional Liability Continue to Improve |
Frederick W. Cheney, M.D.
Committee on Professional Liability
The most recent data from the ASA Committee on Professional Liability's
Closed Claims Project suggest that severe anesthesia-related injuries
such as death and brain damage are becoming less frequent. This
standardized collection of case summaries of adverse anesthesia
related outcomes has been ongoing since 1985 and now contains
about 4,000 claims from 35 insurance companies that insure approximately
14,500 anesthesiologists.
In the 1970s, 56 percent of all claims were for death or permanent
brain damage as compared to 45 percent in the 1980s and 31 percent
in the 1990s [Figure 1]. The most
common source of damaging event or mechanism of causation of death
or brain damage is the respiratory system. Over time, there has
been a significant downward trend in the number of claims for
death or brain damage caused by respiratory system damaging events:
in the 1970s, 55 percent; in the 1980s, 50 percent; and in the
1990s, 45 percent (p<0.05 compared to 1975-79) of total claims
for death or brain damage involved the respiratory system [Figure
2].
On the other hand, cardiovascular damaging events showed just
the opposite trend in that they were responsible for 12 percent
of claims for death and brain damage in the 1970s, 18 percent
in the 1980s and 24 percent in the 1990s [Figure
2]. Equipment-related claims for death and brain damage showed
a slight downward trend over the three decades [Figure
2]. As compared to earlier decades, the number of claims in
the 1990s are too few to achieve statistical differences in the
cardiovascular or equipment groups.
The three most common respiratory system damaging events causing
death or brain damage are inadequate ventilation, esophageal intubation
and difficult intubation [Figure 3].
The most marked reduction among these damaging events was in claims
for inadequate ventilation, which represented 22 percent of all
claims for death or brain damage in the 1970s, 15 percent in the
1980s and only 7 percent in the 1990s [Figure
3]. The incidence of esophageal intubation tended to decrease
as a mechanism of death or brain damage in the 1990s [Figure 3].
Difficult intubation as a cause of death or brain damage increased
from 5 percent in the 1970s to 12 percent in the 1990s [Figure
3]. The number of claims in the 1990s are too few for this
increase in injuries due to difficult intubation to reach statistical
significance.
The question arises as to why claims for death or brain damage
have been decreasing since the 1970s. One answer would seem to
be that pulse oximetry (SpO2) and end-tidal CO2
(ETCO2) have had a major impact on the continuing improvement
in anesthesia patient safety, although the trend seems to have
started before their widespread use [Figure
2]. These two monitors came into use in the mid to late 1980s
and became ASA standards of practice in the early 1990s. The beneficial
effect of improved monitoring is supported by the fact that claims
for injury due to inadequate ventilation and esophageal intubation
have decreased in the 1990s while those for difficult intubation
have not [Figure 4].
SpO2 and ETCO2 monitoring would be expected
to have the greatest effect on the occurrence of injuries from
inadequate ventilation and esophageal intubation and the least
effect on injuries from difficult intubation. This is not surprising,
as placement of an endotracheal tube is a technical act and monitors
do not themselves place endotracheal tubes. (SpO2 monitoring
might give an earlier warning of hypoxemia in the patient in whom
tracheal intubation is being unsuccessfully attempted.) Thus,
the practitioner could direct attention to treating hypoxemia
before it could cause injury. However, SpO2 monitoring
does not seem to have affected the data collected to date [Figure
3].
In an analysis of closed claims data from the 1970s and mid-1980s,
Caplan et al.1 suggested that
injury from difficult intubation would not be prevented by monitoring
and that other strategies would be necessary to prevent these
adverse outcomes. As a result, the ASA appointed a Task Force
on Guidelines for Management of the Difficult Airway, which developed
an evidence-based practice guideline published in 1993.2
The impact of this practice guideline, if present, will not be
reflected in the ASA Closed Claims Project database for several
years as it takes about five years for an adverse event for which
a claim of malpractice is made to be included in the database.
The Closed Claims Project Subcommittee is now evaluating the
role of the practice guideline in its review of all new closed
claims for injury due to difficult intubation. These data should,
in time, reveal whether the guideline is being followed in clinical
practice and, if so, if it is affecting the occurrence of injuries
from difficult intubation. This is an unusual method of evaluation
utilizing a unique database (closed claims) but is important because
most evidence-based practice guidelines do not have any methodologies
in place to evaluate their impact on clinical practice or patient
safety.
Correlated with the aforementioned apparent improvement in patient
safety is an improvement in anesthesia liability. The proportion
of claims for death or brain damage in which care was judged by
the reviewers as below the standard of care at the time of the
event declined from 65 percent in the 1970s to 59 percent in the
1980s to 51 percent (p<.05 compared to the 1970s) in the early
1990s [Figure 5]. It is too early
to tell if this encouraging trend reflects a differential in the
length of claims litigation rather than a true improvement in
anesthesia care because claims with clearly good care may close
more quickly than others.
It should be noted, however, that the Closed Claims Project database
reflects only claims and not all patient injuries, so this liability
pattern may reflect changes in litigation rather than the quality
of anesthesia care. It is possible that plaintiff attorneys are
pursuing claims for death or brain damage that have weaker evidence
of substandard care in the 1990s compared to earlier time periods.
If this is the case, the good news is that fewer claims for death
or brain damage are successfully pursued.
Another encouraging trend is that the proportion of claims for
death and brain damage that resulted in payment to the plaintiff
has declined from 74 percent in the late 1970s to only 40 percent
in the early 1990s (p<.05) [Figure
6]. In fact, among the 100 death or brain damage claims from
the 1990s that have closed and been entered into the database
thus far, just as many were successfully defended without payment
as those that resulted in payment to the plaintiff. This is a
striking contrast from earlier trends in which the majority of
such claims resulted in pay-out [Figure 6].
As data from the 1990s accumulate, it is encouraging to see a
continuing reduction in claims for death or brain damage and an
improvement in the liability profile. Cardiovascular mechanisms
of injury are becoming more prominent as respiratory system mechanisms
are decreasing. This may reflect the fact that SpO2
monitoring allows a more accurate diagnosis of the exact mechanism
of injury.
References:
- Caplan RA, Posner KL, Ward RJ, Cheney
FW. Adverse respiratory events in anesthesia: A closed claims
analysis. Anesthesiology. 1990; 72:828-833.
- Caplan RA, Benumof JL, Berry FA, Blitt
CD, Bode RH, Cheney FW, Connis RT, Guidry OF, Ovassapian A.
Practice guidelines for management of the difficult airway:
A report by the American Society of Anesthesiologists Task Force
on Management of the Difficult Airway. Anesthesiology.
1993; 78:597-602.
Frederick W. Cheney, M.D., is Professor
and Chair, Department of Anesthesiology, University of Washington
School of Medicine, Seattle, Washington.
E-mail the author.
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