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June 1998
Volume 62 |
Number 6
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| Liability Arising
From Anesthesia Gas Delivery Equipment |
Robert A. Caplan, M.D., Chair
Committee on Professional Liability
Almost every piece of medical equipment carries some potential
for misuse or failure. Gas delivery devices are a particular concern
in anesthesia because they exhibit features that may predispose
to critical events. These include the need for multiple connections,
the use of complex mechanical and electrical components, and variations
in manufacture and design. We recently used the American Society
of Anesthesiologists (ASA) Closed Claims Project database to conduct
an in-depth analysis of adverse outcomes associated with the use
of anesthesia gas delivery devices.1 Our goal was to identify
patterns of causation and strategies for prevention that might
not be evident to practitioners who encounter these adverse outcomes
as isolated events.
Key Findings
Gas delivery equipment accounted for 72 of 3,791 claims (2 percent)
in the ASA Closed Claims Project database.1
The most common adverse outcomes were death (47 percent) and brain
damage (29 percent) [Table 1]. The breathing circuit was the most
common source of injury, accounting for 39 percent of gas delivery
claims. Vaporizers, ventilators and oxygen supply tanks or lines
together accounted for 49 percent of these claims. Events associated
with the anesthesia machine itself were comparatively rare (7 percent).
Almost all adverse outcomes occurred in the operating room (86 percent).
The remaining events took place in the postanesthesia care unit
(8 percent) or intensive care unit (6 percent). Claims involving
endotracheal tubes and masks were not included in this study, as
they have been analyzed separately (see Reference
1).
Table 1
Adverse Outcomes Associated With Gas Delivery Equipment
Table One (Click Here)
Equipment misuse was three times more frequent than equipment failure
(75 percent versus 24 percent) [Table 2]. (Misuse was used
to characterize claims in which the injury originated from human
fault or error associated with the preparation, maintenance or deployment
of a medical device; failure was used to characterize claims
in which the device appeared to malfunction unexpectedly, despite
routine maintenance and previous uneventful use.)
Table 2
Misuse and Failure of Gas Delivery Equipment
|
Claims Characterized By |
| Equipment Group |
Misuse |
Failure |
Uncertain |
| Breathing circuit (n=28) |
26 |
2 |
0 |
| Vaporizer (n=15) |
7 |
8 |
0 |
| Ventilator (n=12) |
8 |
3 |
1 |
| Supply tanks or lines (n=8) |
7 |
1 |
0 |
| Anesthesia machine (n=5) |
2 |
3 |
0 |
| Supplemental O2 tubing (n=4) |
4 |
0 |
0 |
| TOTAL (n=72) |
54 (75%) |
17 (24%) |
1 (1%) |
In 70 percent of claims involving misuse, the fault or error arose
directly and almost exclusively from actions of the primary anesthesia
provider. In the remaining 30 percent of claims, misuse arose, at
least in part, from contributory actions of ancillary personnel.
Some examples of contributory actions include the incorrect installation
of gas lines or tanks by construction workers, engineers or service
technicians (7 cases) or the creation of a direct attachment between
an endotracheal tube and a 50-psi oxygen source by nursing personnel
(4 cases).
Misconnects and disconnects of the breathing circuit accounted
for slightly more than two-thirds of claims (25/72; 35 percent).
(A misconnect was defined as a nonfunctional and unconventional
configuration of breathing circuit components or attachments;
a disconnect was defined as the loss of attachment or continuity
in a breathing circuit that was initially configured in a functional
and conventional manner.)
Misconnects were slightly more frequent than disconnects (19
percent versus 15 percent of all gas delivery claims). The three
most frequently specified sites for disconnects and misconnects
were: 1) the junction between the breathing circuit and the gas
delivery outlet of the ventilator (9/25; 36 percent); 2) the junction
between the distal end of the breathing circuit and the endotracheal
tube (4/25; 16 percent); and 3) a location on the inspiratory
limb of the breathing circuit that allowed the interposition of
a positive end-expiratory pressure valve (3/25; 12 percent).
Most of the gas delivery claims resulted from events that took
place in the 1980s (49/72; 68 percent), with occurrence dates
ranging from 1962 to 1991. Of note, claims involving anesthesia
machines, ventilators and oxygen supply lines or tanks all took
place before 1990, while claims involving breathing circuits,
vaporizers and supplemental oxygen tubing continued to occur in
the 1990s.
More than three-fourths of the gas delivery claims (56/72; 78
percent) were considered preventable with the use or better use
of monitoring. Half of the claims (38/72; 53 percent) were considered
preventable if a pulse oximeter, capnograph or both of these two
monitors had been used. Preventive roles were also identified
for other monitors, such as the anesthetic agent analyzer (17
percent), oxygen analyzer (12 percent), airway pressure alarm
(10 percent) and precordial or esophageal stethoscope (1 percent).
In 18 percent of the claims, a monitor or alarm that could have
played a preventive role was physically present but was either
broken, turned off or in a disabled mode.
Claims that were not considered preventable with better monitoring
(16/72; 22 percent) typically involved situations in which a critical
incident progressed rapidly to the point of an injurious physiologic
process. Some examples include barotrauma produced by attaching
an endotracheal tube directly to a 50-psi source of oxygen or
cardiovascular depression produced by spilling a liquid inhalational
agent into the breathing circuit.
Payment was received in 76 percent of gas delivery claims. The
median payment for settlement or jury award was $306,000, with
a payment range of $542 to $6,337,000. This is comparable to payments
for other adverse respiratory events in the Closed Claims Project
database (median $230,000; range $390 to $6,300,000), but significantly
higher than payments for nonrespiratory events (median $50,000;
range $15 to $23,000,000; p <0.01 for payment distributions).
Commentary
During the past two decades, large scale surveys of anesthetic
outcome have identified gas delivery equipment as a small but
recurrent cause of serious injury.2-8 These
studies attribute approximately 1 percent to 5 percent of anesthesia-related
death and brain damage to problems with gas delivery equipment.
The ASA Closed Claims Project presents a similar picture, with
gas delivery equipment accounting for 3 percent of claims for
death and 5 percent of claims for brain damage.
Gas delivery equipment plays a prominent role in critical incident
studies, often contributing to more than 20 percent of all reported
events.9-15 In contrast, claims involving gas
delivery equipment account for only 2 percent (72/3,791) of the
overall ASA Closed Claims Project database. This difference may
arise, at least in part, from the fact that critical incidents
are events that have the potential to cause injury and many critical
incidents are detected and remedied before an identifiable injury
occurs.
Anesthesia gas delivery depends on the use of devices with multiple
connections and moving parts. On this basis, one might expect
equipment failure to play a particularly important role. Instead,
the frequency of equipment misuse was three times greater than
equipment failure. This finding is consistent with previous studies
that have emphasized the prominent role of human error in equipment-related
critical incidents and adverse outcomes.9-12
Of note, the breathing circuit made the single largest contribution
to the misuse of gas delivery equipment (26 of 54 misuse claims;
48 percent). Furthermore, almost all adverse outcomes involving
the breathing circuit arose from either a misconnect or disconnect
(25/28; 89 percent). These findings suggest that a fundamental
re-evaluation of the breathing circuit from a "human factors"
perspective may be a particularly effective strategy for patient
safety efforts.
An interesting aspect of the present study was the observation
that ancillary personnel make an important contribution to the
anesthesiologist's liability. Misuse of equipment by nonanesthesiologists
contributed to patient injury in one-fifth of all gas delivery
claims. This finding suggests that preventive strategies and educational
efforts need to extend beyond the simple conceptual boundaries
of the operating room.
Summary
Claims involving gas delivery equipment represent a small fraction
of the ASA Closed Claims Project database. These claims are characterized
by a high severity of injury, a high cost and a prominent role
for equipment misuse. The breathing circuit represents the single
largest source of gas delivery claims, and almost all of these
claims arise from misconnects or disconnects.
References:
- Caplan RA, Vistica MF, Posner KL, Cheney
FW. Adverse anesthetic outcomes arising from gas delivery equipment:
A closed claims analysis. Anesthesiology. 1987; 87:731-733.
- Utting JE, Gray TC, Shelly FC. Human
misadventure in anaesthesia. Can Anaesth Soc J. 1979;
26:472-478.
- Hovi-Viander M. Death associated with anaesthesia in Finland.
Br J Anaesth. 1980; 52:483-488.
- Keenan RL, Boyan CP. Cardiac arrest due to anesthesia. A
study of incidence and causes. JAMA. 1985; 253:2373-2377.
- Buck N, Devlin HB, Lunn JN. The report of a confidential
inquiry into perioperative deaths. London: Nuffield Provincial
Hospitals Trust, 1987.
- Holland R. Anesthesia-related mortality in Australia. Int
Anesthesiol Clin. 1984; 22:61-71.
- Tiret L, Desmonts JM, Hatton F, Vourc'h G. Complications
associated with anaesthesia. A prospective study in France.
Can Anaesth Soc J. 1986; 33:336-344.
- Chopra V, Bovill JG, Spierdijk J. Accidents, near accidents,
and complications during anaesthesia. A retrospective analysis
of a 10 year period in a teaching hospital. Anaesthesia.
1990; 45:3-6.
- Cooper JB, Newbower RS, Long CD, McPeek BJ.
Preventable anesthesia mishaps: A study of human factors. Anesthesiology.
1978; 49:399-406.
- Chopra V, Bovill JG, Spierdijk J, Koornneef F. Reported significant
observations during anaesthesia: A prospective analysis over
an 18-month period. Br J Anaesth. 1992; 68:13-17.
- Craig J, Wilson ME. A survey of anaesthetic misadventures.
Anaesthesia. 1981; 36:933-936.
- Cooper JB, Newbower RS, Kitz RJ. An analysis of major errors
and equipment failures in anesthesia management: considerations
for prevention and detection. Anesthesiology. 1984; 60:34-42.
- Kumar V, Barcellos WA, Mehta MP, Carter JG. An analysis of
critical incidents in a teaching department for quality assurance.
A survey of mishaps during anaesthesia. Anaesthesia.
1988; 43:879-883.
- Russell WJ, Webb RK, Van der Walt JH, Runciman WB. The Australian
Incident Monitoring Study. Problems with ventilation: An analysis
of 2000 incident reports. Anaesth Intensive Care. 1993;
21:617-620.
- Webb RK, Russell WJ, Klepper I, Runciman WB. The Australian
Incident Monitoring Study. Equipment failure: An analysis of
2000 incident reports. Anaesth Intensive Care. 1993;
21:673-677.
Robert A. Caplan, M.D., is Clinical Professor
of Anesthesiology at the University of Washington and Staff Anesthesiologist
at Virginia Mason Medical Center, Seattle, Washington.
E-mail the author.
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