Downloaded from www.ajronline.org by 14.161.25.162 on 10/28/15 from IP address 14.161.25.162. Copyright ARRS. For personal use only; all rights reserved
1123
Letters
Use of CT for Evaluation Aortic
of Possible
Traumatic
Injury
In their recent
article
in the examination
[1], Richardson
et al. advocate
the use of CT
of patients with blunt decelerating
thoracic
trauma
A major concern with CT as a screening tool is the selection of too many patients with a high probability of aortic injury for CT rather than angiography, thus introducing inordinate delay in the diagnosis and treatment of these injuries. Four (4%) of 90 patients in the series
delays
Richardson et al. who had chest CT had subsequent demonstration aortic injury; the authors do not state whether they consider this acceptable percentage. What is the authors’ current definition of equivocal chest radiograph? Many of the reasons cited for the inability to decide whether the mediastinum was normal (Table 2 in
may be encountered in obtaining urgent CT scans of the chest. Furthermore, in some institutions, radiologists may refuse to perform
[1]) are signs of possible aortic injury listed by the authors, from the same institution as Richardson et al., of an earlier paper [4] on the
angiography
unless
value
aortic
[2]. Advocacy
who
may
trauma
have
center,
aortic
injury.
where
The
authors
experience
patients is optimal for a protocol In institutions
injury
that treat
with
institution. tocol
Our concern
of Richardson
a flagship
management
of such
CT shows
of trauma
patients,
abnormalities
that
of the use of CT as a screening
aortic injury should be tempered that
the
with
such as the one presented.
large numbers
the thoracic
al. do acknowledge
are affiliated
suggest
test for
by these facts, and Richardson
the applicability
of CT may
is that the widespread
vary
adoption
with
et the
of the pro-
et al. will lead to inappropriate
of of an an
of chest
use of CT as a screening examination, thus introducing critical delays in the treatment of patients with aortic injuries, including delay of nonselection
their
of the accurate
mediastinal
standard
examination,
aortography.
radiography
in excluding
traumatic
aortic
rupture.
Indeed, in that earlier publication [4], several of these reasons were listed among those criteria most discriminating of aortic rupture. Is any abnormal chest radiograph now to be considered equivocal for purposes of selection for CT examination? Richardson
et al. advocate
protocol.
However,
the use of contrast-enhanced
they
ment is critical and indicate
fail
to confirm
that
that CT is performed
CT in
contrast
enhance-
mainly to look for
hematoma, which does not require use of IV contrast The use of IV contrast medium to study the mediastinum
The risk of death in the hours after aortic injury is well known and should influence the choice of imaging techniques; it is a major cause of our concern with the use of CT. Is this concern valid? We think it is. In the series presented by Miller et al. [2], two patients became
medium.
so unstable
during angiography
In our own
experience,
able, and higher doses of contrast material are required. In patients suspected of having aortic injury, many of whom
that the procedure
a patient
with
an aortic
was terminated.
injury
died en route
limits
the option
of high-dose
bolus
reinjection
to the operating room from the CT suite after having abdominal CT. Two recent articles [2, 3] from the surgical literature illustrate the complexity of this issue. Miller et al. [2] prospectively evaluated 153 patients with suspected aortic injury, a larger series than that of Richardson et al. Patients had contrast-enhanced CT followed by
less than 40 years old [2, 4], mediastinal
angiography. In five patients, two with a transected aorta and three with injuries to a major aortic branch, the results of CT falsely showed no indications of aortic trauma. Richardson et al. appear to dismiss
resulting indicate
that experience because only two cases involved the aorta-in one patient, IV contrast medium was not used, and in the other, CT retrospectively showed a mediastinal hematoma. Nevertheless, this experience
was
important
because
it included
clinically
significant
examples in which CT showed no evidence of aortic trauma. In a recent article, Fenner et al. [3] recommend CT “for the evaluation of widened mediastinum in the stable patient,” even though (1) only four patients
CT and angiography,
and (2) the
authors admit that small, “subclinical” intimal injuries ruled out in their patients on the basis of CT findings.
in their
series
had both
could not be
of contrast
medium
to
study the abdomen and could have an effect on subsequent aortography, especially when digital subtraction angiography is not avail-
preted incorrectly as residual thymus needed angiography not be performed.
hematoma
are
could be inter-
or a vascular structure, What are the appearances
and of
mediastinal hematoma that allow it to be distinguished from such normal structures? Richardson et al. allude to six equivocal studies
evaluation
from thymic tissue or pulmonary artery averaging but do not how to avoid confusion with mediastinal hematoma. Also,
of the mediastinum
to a nasogastric in pain. A paucity
further to problems Finally,
indicator
may be complicated
by artifacts
due
tube or to motion in patients who are restless and of mediastinalfat in younger patients may contribute
with interpretation.
long-term
of overlooked
alone, was available
radiographic
traumatic
follow-up,
aortic
which
injury
in less than one half (27/63)
the series of Richardson et al. In summary, at our level 1 trauma
center,
may
than clinical
be
a better
follow-up
of the patients
we continue
in
to discour-
age the use of chest CT for suspected aortic injury. We concur with the conclusions presented by Miller et al. [2] in the largest series
LETTERS
i i24
AJR:157,
November
1991
published to date that “chest CT has no screening role in the evaluation of blunt trauma patients with possible major vascular injury.” In this instance, CT may be fool’s gold, and its glitter should
Downloaded from www.ajronline.org by 14.161.25.162 on 10/28/15 from IP address 14.161.25.162. Copyright ARRS. For personal use only; all rights reserved
not distract phy.
us from choosing
the gold standard:
thoracic
angiogra-
John S. Wills James F. Lally Medical
Center of Delaware Newark, DE 19718
REFERENCES
1 . Richardson
P. Mirvis SE, Scorpio A, Dunham CM. Value of CT in deter-
mining the need for angiography when findings of mediastinal hemorrhage on chest radiographs are equivocal. AJR 1991:156:273-279 2. Miller FB, Richardson JD, Thomas HA, Cryer HM, Willing SJ. Role of CT in diagnosis of major arterial injury after blunt thoracic trauma. Surgery 1989:106:596-603
3. Fenner MN, Fisher KS, Sergei NL, Porter DB, Metzmaker
CO. Evaluation
of
possible traumatic thoracic aortic injury using aortography and CT. Am Surg 1990:56:497-499 4. Mirvis SE, Bidwell JK, Buddemeyer EU, et al. Value of chest radiography in excluding traumatic aortic rupture. Radiology 1987:163:487-493
Fig. 1.-Equivocal
radiograph and
CT scan of thoracic aortic rupture. A, Admission erect chest radiograph of a young man who had fallen
30 ft (9 m) was initially interpreted showing
Reply We appreciate the thoughtful We share their genuine concern
First,
when
an institution
has
a large
number
of patients
trauma who may have major arterial thoracic injury, graph, specifically the appearance of the mediastinal
be evaluated.
As in all aspects
tion of the chest depends
on
mandatory
radiograph
training thoracic
significant
thoracic
and unreasonably patients
are treated
and
of diagnostic Although
arteriography decelerating
costly
in all trauma,
approach
at a given
we think when
a history
number
In general,
of
patients
of
shown
by erect chest
radiographs, one
should third
with
Center, 85are spared contour,
have prompt
of these
without
additional
situations
(1) pa-
tients with multisystem injury, particularly spinal fractures or pelvic ring disruption, for whom an erect chest radiograph is not safe; (2) patients in whom technically satisfactory chest radiographs cannot be acquired because of the patients’ body habitus or lack of cooperation for the study; and (3) patients whose chest radiographs show a “near normal” mediastinum but who may have vascular ectasia, pulmonary
contusion,
obliterates permit
aspiration,
pleural
a portion of the mediastinal
an unequivocal
interpretation
effusion,
or atelectasis
border and therefore of the mediastinum
In our center,
CT scanning
that
does not
as normal.
arteriography
on all patients
experience to date CT as an ancillary
is immediately
available,
care facilities.
which
should
In this circumstance,
CT scanning usually is performed before arteriography for all trauma patients who require urgent CT evaluation, even when arteriography is indicated, simply because CT is generally available more rapidly. The dynamic thoracic CT study for detection of mediastinal hemorrhage requires less than 1 0 mm and is almost always performed along with other required CT examinations. In circumstances in which high
findings
include
thoracic
be the case in all major trauma
our traumatologists
injury of a great vessel, depending on whether the mediastinal hemorrhage is based on findings on the erect chest radiograph [3]. situations, the chest radiograph, supine or erect, may Some
by arteriography.
screening procedure to detect mediastinal hemorrhage in these selooted patients (CT was performed in 7% of our patients admitted because of blunt chest trauma [1]).
patients
will have an diagnosis of supine or the In several
hematoma.
of these
as
In our experience,
of mediastinal
fifth
Some may elect to perform
thoracic
angiography.
not show a sharply defined aortic contour
to one
firmed immediately
such
normal mediastinal contours should not have further workup for thoracic vascular injury, unless indicated by clinical findings such as a significant pulse deficit. At the Maryland Shock-Trauma 87% of patients with a history of blunt chest trauma further workup on this basis. Patients with obvious abnormality of the mediastinal
shows an intimal and pseudoaneuof proximal dowhich were con-
B
who fall into these categories. However, our supports the use of dynamic contrast-enhanced
is an impractical
this
a large
institution.
the interpreta-
with
contrast-enhanced
blunt
of mediastinal anatomy some [2] advocate
patients
B, Dynamic thoracic CT scan flap (solid arrow) rysm (open arrows) scending aorta,
the chest radiocontour, should
imaging,
and evaluation experience.
with
as
of mediastinal
hemorrhage, but some concern about aortic arch region was raised.
comments of Drs. Wills and Lally. that CT might be applied inappro-
priately in evaluation of the thorax in patients with significant decelerating trauma and potential injury to the great vessel. In our article [1 ], we and our coauthors attempted to emphasize several caveats for the use of thoracic CT in this clinical setting.
no evidence
probability
think that the mechanism
of thoracic
arterial
injury,
of injury indicates
angiography
may
formed regardless of the appearance of the admission graph, although this has been distinctly rare.
be
chest
a
per-
radio-
As described in our article [1], we do not think that the experience of Miller et al. [4] significantly negates our recommendations about the appropriate
use of CT. We think
that excellent
enhancement
of
the vascular structures of the mediastinum is needed to optimize the accuracy of interpretation. Equivocal CT studies, seen early in our experience,
often
were
related
to
hand-injected
and
poorly
timed
boluses of contrast medium. Although direct visualization of a vascular injury is not required for a positive CT study, the presence of IV contrast medium may make this possible (Fig. 1) nonetheless. If the abdomen also is to be studied by CT, we do not give the patient another bolus of contrast medium but continue the scan dynamically through the abdomen with a continuous IV infusion. Parenchymal enhancement
within
the
abdomen
is not
significantly
degraded
when
LETTERS
AJR:157, November1991
this
protocol
is
used. In order to decrease
the total dose of contrast
medium administered, enhanced thoracic CT should be used only as an ancillary screening test for mediastinal hemorrhage, if intraarterial digital subtraction angiography is available, which requires less con-
Downloaded from www.ajronline.org by 14.161.25.162 on 10/28/15 from IP address 14.161.25.162. Copyright ARRS. For personal use only; all rights reserved
trast material than conventional cut-film thoracic artenography. Our experience to date has shown that the proper selection
1125
gauze stack and beyond control of the guidewire
(Fig. 1). Next, the needle is withdrawn while and puncture site is maintained. Residents
can practice exchanging dilators and catheters over the guidewire [1 The gauze sponges remain stationary while allowing easy passage of wines, dilatons, and catheters. ].
of
Manual dexterity and familiarity with basic angiographic techniques of percutaneous catheterization are essential to the successful per-
here,
and will eliminate many unnecessary thoracic arteriograms. We strongly urge the use of immediate thoracic arteriography when the
formance of arteriograms. By using this simple method, residents can practice the Seldinger technique [1 1 and learn to exchange catheters before they perform an arteriogram. Although the tactile
admission
sensation
patients
for contrast-enhanced
hemorrhage
dynamic
CT to exclude
is safe, if used in the circumstances
chest radiograph
reveals evidence
mediastinal
as described
of mediastinal
hemor-
residents
nhage. Stuart C. Michael
University
E. Mirvis
of arterial
puncture
can practice
is not
exchanges
reproduced
method,
of guidewires
and catheters. David J. Eschelman
Dunham
Alan J. Greenfield Douglas T. Gibbens
of Maryland Medical Systems Baltimore, MD 21201 Boston
REFERENCES 1 . Richardson P, Mirvis SE, Scorpio R, Dunham CM. Value of CT in determining the need for angiography when findings of mediastinal hemorrhage on chest radiographs are equivocal. AJR 1991 :1 56 :273-279 2. Jackson DH. Of TRAs and ROCs. chest 1984:85:595-597
3. Mirvis SE, Bidwell JK, Buddemeyer, et al. Value of chest radiography excluding aortic rupture. Radiology 1987:163:487-493
by this
and manipulations
University Medical Center Boston, MA 02118
REFERENCE 1 . Seldinger SI. Catheter replacement raphy. Acta Radiol 1953:39:368-376
of the needle
in percutaneous
angiog-
in
4. Miller FB, Richardson JD, Hots AT, Cujer HM, Willig SR. Role of CT in diagnosis of major arterial injury after blunt thoracic trauma. Surgery
1989:106:596-603
Subclavian
Vein
and Dialysis
Access
Planning
We read the article by Surratt et al. [1] with great interest. In our [2], we had similar findings: a 5O% prevalence of subclavian
series
stenosis after temporary placement of a dialysis catheter in the subclavian vein. We think additional points should be made that were
In Vitro Method for Teaching Vascular Catheterization We describe a simple to perform percutaneous
a guidewire. A 2.5-cm
not in the paper of Surratt et al.
Percutaneous
The length of time the subclavian In our series of 30 patients who
in vitro method for teaching residents vascular catheterization and exchange
how over
vein the
and
duration
in whom
36 subclavian
of catheterization
was
venograms significantly
were perlonger
(p
1123
Letters
Use of CT for Evaluation Aortic
of Possible
Traumatic
Injury
In their recent
article
in the examination
[1], Richardson
et al. advocate
the use of CT
of patients with blunt decelerating
thoracic
trauma
A major concern with CT as a screening tool is the selection of too many patients with a high probability of aortic injury for CT rather than angiography, thus introducing inordinate delay in the diagnosis and treatment of these injuries. Four (4%) of 90 patients in the series
delays
Richardson et al. who had chest CT had subsequent demonstration aortic injury; the authors do not state whether they consider this acceptable percentage. What is the authors’ current definition of equivocal chest radiograph? Many of the reasons cited for the inability to decide whether the mediastinum was normal (Table 2 in
may be encountered in obtaining urgent CT scans of the chest. Furthermore, in some institutions, radiologists may refuse to perform
[1]) are signs of possible aortic injury listed by the authors, from the same institution as Richardson et al., of an earlier paper [4] on the
angiography
unless
value
aortic
[2]. Advocacy
who
may
trauma
have
center,
aortic
injury.
where
The
authors
experience
patients is optimal for a protocol In institutions
injury
that treat
with
institution. tocol
Our concern
of Richardson
a flagship
management
of such
CT shows
of trauma
patients,
abnormalities
that
of the use of CT as a screening
aortic injury should be tempered that
the
with
such as the one presented.
large numbers
the thoracic
al. do acknowledge
are affiliated
suggest
test for
by these facts, and Richardson
the applicability
of CT may
is that the widespread
vary
adoption
with
et the
of the pro-
et al. will lead to inappropriate
of of an an
of chest
use of CT as a screening examination, thus introducing critical delays in the treatment of patients with aortic injuries, including delay of nonselection
their
of the accurate
mediastinal
standard
examination,
aortography.
radiography
in excluding
traumatic
aortic
rupture.
Indeed, in that earlier publication [4], several of these reasons were listed among those criteria most discriminating of aortic rupture. Is any abnormal chest radiograph now to be considered equivocal for purposes of selection for CT examination? Richardson
et al. advocate
protocol.
However,
the use of contrast-enhanced
they
ment is critical and indicate
fail
to confirm
that
that CT is performed
CT in
contrast
enhance-
mainly to look for
hematoma, which does not require use of IV contrast The use of IV contrast medium to study the mediastinum
The risk of death in the hours after aortic injury is well known and should influence the choice of imaging techniques; it is a major cause of our concern with the use of CT. Is this concern valid? We think it is. In the series presented by Miller et al. [2], two patients became
medium.
so unstable
during angiography
In our own
experience,
able, and higher doses of contrast material are required. In patients suspected of having aortic injury, many of whom
that the procedure
a patient
with
an aortic
was terminated.
injury
died en route
limits
the option
of high-dose
bolus
reinjection
to the operating room from the CT suite after having abdominal CT. Two recent articles [2, 3] from the surgical literature illustrate the complexity of this issue. Miller et al. [2] prospectively evaluated 153 patients with suspected aortic injury, a larger series than that of Richardson et al. Patients had contrast-enhanced CT followed by
less than 40 years old [2, 4], mediastinal
angiography. In five patients, two with a transected aorta and three with injuries to a major aortic branch, the results of CT falsely showed no indications of aortic trauma. Richardson et al. appear to dismiss
resulting indicate
that experience because only two cases involved the aorta-in one patient, IV contrast medium was not used, and in the other, CT retrospectively showed a mediastinal hematoma. Nevertheless, this experience
was
important
because
it included
clinically
significant
examples in which CT showed no evidence of aortic trauma. In a recent article, Fenner et al. [3] recommend CT “for the evaluation of widened mediastinum in the stable patient,” even though (1) only four patients
CT and angiography,
and (2) the
authors admit that small, “subclinical” intimal injuries ruled out in their patients on the basis of CT findings.
in their
series
had both
could not be
of contrast
medium
to
study the abdomen and could have an effect on subsequent aortography, especially when digital subtraction angiography is not avail-
preted incorrectly as residual thymus needed angiography not be performed.
hematoma
are
could be inter-
or a vascular structure, What are the appearances
and of
mediastinal hematoma that allow it to be distinguished from such normal structures? Richardson et al. allude to six equivocal studies
evaluation
from thymic tissue or pulmonary artery averaging but do not how to avoid confusion with mediastinal hematoma. Also,
of the mediastinum
to a nasogastric in pain. A paucity
further to problems Finally,
indicator
may be complicated
by artifacts
due
tube or to motion in patients who are restless and of mediastinalfat in younger patients may contribute
with interpretation.
long-term
of overlooked
alone, was available
radiographic
traumatic
follow-up,
aortic
which
injury
in less than one half (27/63)
the series of Richardson et al. In summary, at our level 1 trauma
center,
may
than clinical
be
a better
follow-up
of the patients
we continue
in
to discour-
age the use of chest CT for suspected aortic injury. We concur with the conclusions presented by Miller et al. [2] in the largest series
LETTERS
i i24
AJR:157,
November
1991
published to date that “chest CT has no screening role in the evaluation of blunt trauma patients with possible major vascular injury.” In this instance, CT may be fool’s gold, and its glitter should
Downloaded from www.ajronline.org by 14.161.25.162 on 10/28/15 from IP address 14.161.25.162. Copyright ARRS. For personal use only; all rights reserved
not distract phy.
us from choosing
the gold standard:
thoracic
angiogra-
John S. Wills James F. Lally Medical
Center of Delaware Newark, DE 19718
REFERENCES
1 . Richardson
P. Mirvis SE, Scorpio A, Dunham CM. Value of CT in deter-
mining the need for angiography when findings of mediastinal hemorrhage on chest radiographs are equivocal. AJR 1991:156:273-279 2. Miller FB, Richardson JD, Thomas HA, Cryer HM, Willing SJ. Role of CT in diagnosis of major arterial injury after blunt thoracic trauma. Surgery 1989:106:596-603
3. Fenner MN, Fisher KS, Sergei NL, Porter DB, Metzmaker
CO. Evaluation
of
possible traumatic thoracic aortic injury using aortography and CT. Am Surg 1990:56:497-499 4. Mirvis SE, Bidwell JK, Buddemeyer EU, et al. Value of chest radiography in excluding traumatic aortic rupture. Radiology 1987:163:487-493
Fig. 1.-Equivocal
radiograph and
CT scan of thoracic aortic rupture. A, Admission erect chest radiograph of a young man who had fallen
30 ft (9 m) was initially interpreted showing
Reply We appreciate the thoughtful We share their genuine concern
First,
when
an institution
has
a large
number
of patients
trauma who may have major arterial thoracic injury, graph, specifically the appearance of the mediastinal
be evaluated.
As in all aspects
tion of the chest depends
on
mandatory
radiograph
training thoracic
significant
thoracic
and unreasonably patients
are treated
and
of diagnostic Although
arteriography decelerating
costly
in all trauma,
approach
at a given
we think when
a history
number
In general,
of
patients
of
shown
by erect chest
radiographs, one
should third
with
Center, 85are spared contour,
have prompt
of these
without
additional
situations
(1) pa-
tients with multisystem injury, particularly spinal fractures or pelvic ring disruption, for whom an erect chest radiograph is not safe; (2) patients in whom technically satisfactory chest radiographs cannot be acquired because of the patients’ body habitus or lack of cooperation for the study; and (3) patients whose chest radiographs show a “near normal” mediastinum but who may have vascular ectasia, pulmonary
contusion,
obliterates permit
aspiration,
pleural
a portion of the mediastinal
an unequivocal
interpretation
effusion,
or atelectasis
border and therefore of the mediastinum
In our center,
CT scanning
that
does not
as normal.
arteriography
on all patients
experience to date CT as an ancillary
is immediately
available,
care facilities.
which
should
In this circumstance,
CT scanning usually is performed before arteriography for all trauma patients who require urgent CT evaluation, even when arteriography is indicated, simply because CT is generally available more rapidly. The dynamic thoracic CT study for detection of mediastinal hemorrhage requires less than 1 0 mm and is almost always performed along with other required CT examinations. In circumstances in which high
findings
include
thoracic
be the case in all major trauma
our traumatologists
injury of a great vessel, depending on whether the mediastinal hemorrhage is based on findings on the erect chest radiograph [3]. situations, the chest radiograph, supine or erect, may Some
by arteriography.
screening procedure to detect mediastinal hemorrhage in these selooted patients (CT was performed in 7% of our patients admitted because of blunt chest trauma [1]).
patients
will have an diagnosis of supine or the In several
hematoma.
of these
as
In our experience,
of mediastinal
fifth
Some may elect to perform
thoracic
angiography.
not show a sharply defined aortic contour
to one
firmed immediately
such
normal mediastinal contours should not have further workup for thoracic vascular injury, unless indicated by clinical findings such as a significant pulse deficit. At the Maryland Shock-Trauma 87% of patients with a history of blunt chest trauma further workup on this basis. Patients with obvious abnormality of the mediastinal
shows an intimal and pseudoaneuof proximal dowhich were con-
B
who fall into these categories. However, our supports the use of dynamic contrast-enhanced
is an impractical
this
a large
institution.
the interpreta-
with
contrast-enhanced
blunt
of mediastinal anatomy some [2] advocate
patients
B, Dynamic thoracic CT scan flap (solid arrow) rysm (open arrows) scending aorta,
the chest radiocontour, should
imaging,
and evaluation experience.
with
as
of mediastinal
hemorrhage, but some concern about aortic arch region was raised.
comments of Drs. Wills and Lally. that CT might be applied inappro-
priately in evaluation of the thorax in patients with significant decelerating trauma and potential injury to the great vessel. In our article [1 ], we and our coauthors attempted to emphasize several caveats for the use of thoracic CT in this clinical setting.
no evidence
probability
think that the mechanism
of thoracic
arterial
injury,
of injury indicates
angiography
may
formed regardless of the appearance of the admission graph, although this has been distinctly rare.
be
chest
a
per-
radio-
As described in our article [1], we do not think that the experience of Miller et al. [4] significantly negates our recommendations about the appropriate
use of CT. We think
that excellent
enhancement
of
the vascular structures of the mediastinum is needed to optimize the accuracy of interpretation. Equivocal CT studies, seen early in our experience,
often
were
related
to
hand-injected
and
poorly
timed
boluses of contrast medium. Although direct visualization of a vascular injury is not required for a positive CT study, the presence of IV contrast medium may make this possible (Fig. 1) nonetheless. If the abdomen also is to be studied by CT, we do not give the patient another bolus of contrast medium but continue the scan dynamically through the abdomen with a continuous IV infusion. Parenchymal enhancement
within
the
abdomen
is not
significantly
degraded
when
LETTERS
AJR:157, November1991
this
protocol
is
used. In order to decrease
the total dose of contrast
medium administered, enhanced thoracic CT should be used only as an ancillary screening test for mediastinal hemorrhage, if intraarterial digital subtraction angiography is available, which requires less con-
Downloaded from www.ajronline.org by 14.161.25.162 on 10/28/15 from IP address 14.161.25.162. Copyright ARRS. For personal use only; all rights reserved
trast material than conventional cut-film thoracic artenography. Our experience to date has shown that the proper selection
1125
gauze stack and beyond control of the guidewire
(Fig. 1). Next, the needle is withdrawn while and puncture site is maintained. Residents
can practice exchanging dilators and catheters over the guidewire [1 The gauze sponges remain stationary while allowing easy passage of wines, dilatons, and catheters. ].
of
Manual dexterity and familiarity with basic angiographic techniques of percutaneous catheterization are essential to the successful per-
here,
and will eliminate many unnecessary thoracic arteriograms. We strongly urge the use of immediate thoracic arteriography when the
formance of arteriograms. By using this simple method, residents can practice the Seldinger technique [1 1 and learn to exchange catheters before they perform an arteriogram. Although the tactile
admission
sensation
patients
for contrast-enhanced
hemorrhage
dynamic
CT to exclude
is safe, if used in the circumstances
chest radiograph
reveals evidence
mediastinal
as described
of mediastinal
hemor-
residents
nhage. Stuart C. Michael
University
E. Mirvis
of arterial
puncture
can practice
is not
exchanges
reproduced
method,
of guidewires
and catheters. David J. Eschelman
Dunham
Alan J. Greenfield Douglas T. Gibbens
of Maryland Medical Systems Baltimore, MD 21201 Boston
REFERENCES 1 . Richardson P, Mirvis SE, Scorpio R, Dunham CM. Value of CT in determining the need for angiography when findings of mediastinal hemorrhage on chest radiographs are equivocal. AJR 1991 :1 56 :273-279 2. Jackson DH. Of TRAs and ROCs. chest 1984:85:595-597
3. Mirvis SE, Bidwell JK, Buddemeyer, et al. Value of chest radiography excluding aortic rupture. Radiology 1987:163:487-493
by this
and manipulations
University Medical Center Boston, MA 02118
REFERENCE 1 . Seldinger SI. Catheter replacement raphy. Acta Radiol 1953:39:368-376
of the needle
in percutaneous
angiog-
in
4. Miller FB, Richardson JD, Hots AT, Cujer HM, Willig SR. Role of CT in diagnosis of major arterial injury after blunt thoracic trauma. Surgery
1989:106:596-603
Subclavian
Vein
and Dialysis
Access
Planning
We read the article by Surratt et al. [1] with great interest. In our [2], we had similar findings: a 5O% prevalence of subclavian
series
stenosis after temporary placement of a dialysis catheter in the subclavian vein. We think additional points should be made that were
In Vitro Method for Teaching Vascular Catheterization We describe a simple to perform percutaneous
a guidewire. A 2.5-cm
not in the paper of Surratt et al.
Percutaneous
The length of time the subclavian In our series of 30 patients who
in vitro method for teaching residents vascular catheterization and exchange
how over
vein the
and
duration
in whom
36 subclavian
of catheterization
was
venograms significantly
were perlonger
(p
