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September 2000
Volume 64 |
Number 9
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| Postoperative
Visual Loss Data Gathered and Analyzed |
Lorri Anne Lee, M.D
Postoperative visual loss is one of the most devastating complications
that has been reported to occur after cardiopulmonary bypass,
neck dissection, general surgical abdominal procedures, hip arthroplasty,
craniotomies, thyroidectomy and prone spine cases. The incidence
of symptomatic postoperative visual loss varies depending upon
the population studied and has been reported as low as one in
60,965 for all nonocular operations and as high as 3.6 percent
in cardiopulmonary bypass cases.1,2 Atheromatous, or
air emboli, prolonged hypotension and anemia, inadequate venous
drainage of the globe and direct pressure to the eye have all
been implicated as causative factors.
Ischemic optic neuropathy is the most common diagnosis in postoperative
visual loss. Ischemic optic neuropathy is divided into anterior
and posterior, depending upon the location of the lesion on the
optic nerve. The majority of anterior ischemic optic neuropathy
cases occur during cardiopulmonary bypass procedures (53 percent),
followed by prone spine cases (12 percent). Most posterior ischemic
optic neuropathy cases have occurred during neck, nose or sinus
operations (48 percent) followed by prone spine cases (16 percent)
and cardiopulmonary bypass procedures (11 percent).2
Case reports and retrospective reviews have suggested that although
direct compression of the globe can cause postoperative blindness,
it seldom occurs intraoperatively. Postoperative ischemic optic
neuropathy has occurred in patients in the prone position whose
eyes are free from compression with the head in Mayfield pins
and during cardiopulmonary bypass cases in the supine position.3
Procedure-dependent factors that have been suggested to be associated
with the development of postoperative ischemic optic neuropathy
are: large estimated blood loss, systemic hypotension, long duration
of procedure and anemia.2,4,5 Patient-dependent factors
include hypertension, tobacco use, atherosclerosis, diabetes and
morbid obesity.2,4,5 Outside the hospital setting,
anterior ischemic optic neuropathy is one of the most common causes
of sudden visual loss in middle-aged and elderly people. In these
nonoperative cases, risk factors include atherosclerosis, hypertension,
diabetes mellitus and nocturnal hypotension, among others.6
The etiology of postoperative ischemic optic neuropathy is unclear
but may be associated with decreased oxygen delivery to the optic
nerve.4 Severe and/or prolonged hypotension has frequently
been associated with postoperative ischemic optic neuropathy,
particularly when it is combined with anemia. However, it is important
to emphasize that cases of postoperative ischemic optic neuropathy
have occurred in the absence of these factors. Many cases of postoperative
ischemic optic neuropathy are reported from head and neck dissections
and prone spine procedures where there is significant facial swelling
and where venous hemodynamics may be altered.
Due to a perceived increase in the incidence of postoperative
visual loss over the last decade, the ASA Committee on Professional
Liability established the Postoperative Visual Loss Database on
July 1, 1999, in order to better identify associated risk factors
so that this tragic complication might be prevented in the future.
Patients who develop visual deficits within seven days after nonophthamologic
surgery are eligible for inclusion in the registry, and data are
collected on standardized forms from the registry Web site . Information is collected anonymously, and reporting is
voluntary.
Thus far, we have received and analyzed data on 23 patients.
The most common operations associated with postoperative visual
loss were spine surgery in the prone position (57 percent) followed
by procedures using cardiopulmonary bypass (22 percent) [Table
1]. Ischemic optic neuropathy was diagnosed or strongly suspected
in 20 out of the 23 cases. The other three cases were diagnosed
as either central retinal artery obstruction, retinal ischemia
or a questionable transient ischemic attack. All 23 cases involved
an anesthetic time of more than 5.5 hours and a median estimated
blood loss of 2.2 liters (range 100ml to >12 liters). Significant
hypotension (defined as systolic blood pressure or mean arterial
pressure Ž 40 percent below baseline) was present in 52 percent
of cases. Controlled hypotension was utilized in 42 percent of
these cases. The lowest hematocrit during the operation averaged
25 percent (range 13 to 40 percent). Bilateral lesions were present
in 56 percent of the 23 patients. There was partial recovery of
vision in 39 percent of patients in the database overall, consistent
with a reported partial recovery rate of 30 percent to 43 percent.5,7
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Table 1
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Procedure-Dependent
Associated Factors
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| Variable |
All Cases (n=23) |
| Procedure |
CPB* 5 (22 percent)
Prone 13 (56 percent)
Other 5 (22 percent) |
| OR* Time (median) |
9.9 hrs (range 5.75 to 18 hrs) |
| EBL* (median) |
2.2 liters (range 100 ml to > 12,000 ml) |
| Hypotension |
12 (52 percent) |
| Lowest Hct*(median) |
24.5 percent (range 13-40 percent) |
| Percent Bilateral Lesions |
13 (56 percent) |
| Partial Recovery of Vision |
9 (39 percent) |
| AION* |
8 (35 percent) |
| PION* |
11 (48 percent) |
| *OR = operating room, EBL
= estimated blood loss, Hct = hematocrit, AION = anterior
ischemic optic neuropathy, PION = posterior ischemic
neuropathy, CPB = cardiopulmonary bypass. |
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Data on preoperative or patient-dependent factors cited in other
series were collected (Table 2). Median patient age was 58 years.
Obesity was present in 57 percent, hypertension in 48 percent,
diabetes mellitus in 22 percent, atherosclerotic disease in 48
percent, a smoking history in 52 percent and superior vena cava
syndrome in one patient. Only two of the 23 patients had no known
preoperative patient-related factors. Of these two patients, one
patient had a prolonged back operation (10.3 hours) with significant
hypotension for brief periods of time, and the other patient received
an anesthetic with controlled hypotension and dropped his hematocrit
to 24 percent.
| Table 2 |
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Patient-Dependent
Associated Factors
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| Variable |
All Cases (n=23) |
| Median Age (range) |
58 (24-73) years |
| Obesity (percent cases) |
13 (56 percent) |
| Hypertension |
11 (48 percent) |
| Diabetes Mellitus |
5 (22 percent) |
| Smoking History |
12 (52 percent) |
| Atherosclerosis |
12 (52 percent) |
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There has been speculation that postoperative visual loss in supine
operations that do not involve head and neck surgery are due primarily
to hypotension and/or anemia in patients with occlusive vascular
disease.6 In contrast, venous congestion may be more
important in head and neck procedures and in prone spine operations,
perhaps in association with hypotension and/or anemia.8
This concept is supported by previously published case series
in which anterior ischemic optic neuropathy is most commonly diagnosed
in supine cases (mostly cardiopulmonary bypass cases) in patients
with atherosclerotic disease, while posterior ischemic optic neuropathy
is most commonly diagnosed in prone operations or in cases in
which the venous pressure of the head and neck is elevated.2
The fact that the different types of operations are not equally
distributed between anterior and posterior ischemic optic neuropathy
suggests that the etiology of visual loss differs between the
two.
Although our data support this hypothesis, the number of cases
reported thus far is too small to draw any conclusions, and any
data published at this time must be considered preliminary. We
need additional cases of postoperative visual loss in order for
the database to provide meaningful data. This project is expanding
to be prospective in scope, accepting reports of cases occurring
after 1999 (pending institutional review board approval), which
will make more cases available and make it easier to reach the
goal of 100 cases for analysis.
For more information, please visit our Web
site and see our poster presentation at the ASA 2000 Annual
Meeting in San Francisco on October 16, 2000, in the Moscone Center,
Exhibit Hall A-C. Information on postoperative visual loss and
the database will also be available at the Anesthesia Patient
Safety Foundation exhibit area at the ASA Annual Meeting.
Lorri Anne Lee, M.D., is staff
anesthesiologist at Group Health Permanente, Seattle, Washington,
and Acting Assistant Professor, Department of Anesthesiology,
University of Washington, Harborview Medical Center, Seattle,
Washington.
References:
- Roth S, Thisted RA, Erickson JP, et al. Eye injuries after
nonocular surgery. Anesthesiology. 1996; 85:1020-1027.
- Roth S, Gillesberg I. Injuries to the visual system and other
sense organs. In: Benumof, Saidman LJ. eds. Anesthesia and Perioperative
Complications. 2nd Ed. St. Louis, Missouri: Mosby. 1999:377-408.
- Roth S, Roizen M. Optic nerve injury: Role of the anesthesiologist?
Anesth Analg. 1996; 82:426-439.
- Williams EL, Hart WM, Tempelhoff R. Postoperative ischemic
optic neuropathy. Anesth Analg. 1995; 80:1018-1029.
- Myers MA, Hamilton SR, Bogosian AJ, et al. Visual loss as
a complication of spine surgery. Spine. 1997; 22(12):1325-1329.
- Hayreh SS. Anterior ischemic optic neuropathy. Clinical Neuroscience.
1997; 4:251-263.
- The Ischemic Optic Neuropathy Decompression Trial Research
Group. Optic nerve decompression surgery for nonarteritic anterior
ischemic optic neuropathy (NAION) is not effective and may be
harmful. JAMA. 1995; 273:625-632.
- Dilger JA, Tetzlaff JE, Bell GR, et al. Ischaemic optic neuropathy
after spinal fusion. Can J Anaesth. 1998; 45 (1):63-66.
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