Insufflation Agents for Endoscopy - Bracco Diagnostic Inc.

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Insufflation Agents
for Endoscopy
Carbon Dioxide versus Room Air
BRACCO EDUCATIONAL

Insufflation Agents for Endoscopy:
Carbon Dioxide versus Room Air
Lawrence J. Brandt MD,
MACG, AGA-F, FASGE, FACP, FAACH
Professor of Medicine and Surgery,
Albert Einstein College of Medicine
Chief, Division of Gastroenterology,
Montefiore Medical Center
Purpose: To determine if carbon dioxide (CO 2 ) is a better alternative to room air (RA)
for colonic insufflation due to its rapid absorption, vasodilating effects and lack of
combustibility.
Background: Dr. Brandt and colleagues were interested in the rapid absorption and
clearance of CO 2 , particularly for use in patients with suspected colon ischemia who were
to be colonoscoped. They posited that diminishing the duration of colon distention might
help minimize reductions in colon blood flow resulting from the distention. The known
vasodilating effect of CO 2 in many vascular beds provided an additional incentive for the
group to study the response of colon blood flow to intraluminal insufflation with CO 2 .
Materials and Methods: Inferior mesenteric artery blood flow in greyhound dogs
was measured before, during and after insufflation of the colon with RA and CO 2 under
conditions of transient and constant elevations of intraluminal pressures. In addition to our
own research, we reviewed other published studies comparing CO 2 insufflation with that of
RA.
Conclusion: In our study, intraluminal pressures remained elevated for briefer periods after CO 2
administration, and blood flow was far less compromised, than with RA. Based upon these results and
the evaluation of several other published studies comparing CO 2 with RA, we concluded that CO 2 is
the preferred agent for colonic insufflation. In addition, an automated insufflation system has several
advantages over a manual technique and should be the preferred method of administration.
Introduction
Most physicians do not critically evaluate their use of RA to insufflate the GI tract during endoscopic
procedures yet, many of them have also been faced with a patient who after endoscopy (usually
colonoscopy) complains of abdominal pain and distention, sometimes for days after the procedure. CO 2 is
an attractive alternative insufflation agent compared with RA because its rapid absorption leads to a more
comfortable recovery.
Room air is a mixture of gases (78% nitrogen, 20% oxygen, and trace amounts of other gases). The
presence of oxygen makes it potentially explosive. Use of CO 2 as an insufflating agent was first suggested
to minimize the risk of explosion with electrosurgical polypectomy. 1 Colonic explosions, although rare,
are still reported and recently have been documented during argon plasma coagulation of adenomas and
radiation proctitis. 2 The greater safety of CO 2 is based primarily upon its inability to support combustion,
in contrast to RA in which the O 2 content allows such a reaction. But, CO 2 also serves to reduce the
concentrations of the other bacterially-derived combustible gases in the lower bowel, including hydrogen,
methane, ammonia and hydrogen sulfide, which might accompany poor preparation for the procedure.
The presence of any stool in the colon, including stool in the right colon when electrical current is used in
the left colon or rectum, constitutes a potential danger for explosion. 2

Advantages of Carbon Dioxide
Carbon dioxide is absorbed 150x faster than
nitrogen and is promptly eliminated via the lungs. 3 It,
therefore, results in a more comfortable examination
and its use has been recommended not only for
colonoscopy but also for double-contrast barium
enema examinations. 4-5 In 1984, Hussein and
colleagues reported that with CO 2 insufflation during
colonoscopy, there was no significant residual gas
on plain films taken 30 minutes after the procedure.
In contrast, patients examined after RA insufflation
Arterio-venous oxygen difference (vol %)
16
12
8
4
0
Blood flow (% of control)
160
120
80
40
0
A - V diff
Blood flow
0 30 60 90 120 150 180
Intraluminal pressure (mm Hg)
Figure 1. Effects of bowel distention on blood flow and on arterio-venous
difference of intestinal blood. 7
showed excessive distention of the small and large
bowel. 4 It is surprising how much gas actually is
instilled into the colon during colonoscopy. In a
study by Bretthauer et al, insufflation of ~8.2 liters
with a range of 1.2-19.8 liters was documented
during routine colonoscopy. 6
Another advantage of the rapid absorption of CO 2
is the lack of need to aspirate gas upon withdrawal.
This may result in a decrease in miss-rate of polyps
that otherwise might have been obscured behind a
collapsed fold.
Study Results:
Carbon Dioxide vs. Room Air
The rapid absorption and clearance of CO 2
seemed particularly advantageous in patients
with suspected colon ischemia who were to be
colonoscoped. We postulated that by diminishing
the duration of colon distention, any reduction in
colon blood flow resulting from the distention would
be minimized. Previous studies had shown that
distention of the bowel and elevation of intraluminal
pressure >30 mmHg diminished intestine/colon
blood flow (Figure 1), and it was known that such
intraluminal pressures may be generated during
colonoscopy. 7-8 The known vasodilating effect of
CO 2 in many vascular beds provided an additional
Blood Flow (Percent of Control)
140
120
100
80
60
40
20
Colonic Contraction
IMA Blood Flow
Intracolonic Pressure
2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
Time in Minutes
Baseline
Pressure (6mmHg)
incentive for the group to study the response of
colon blood flow to intraluminal insufflation with
this agent. 9-10
Figure 2. Simultaneous display of inferior mesenteric artery blood flow
and colonic intraluminal pressure following transient elevation of pressure
to 35 mmHg with room air. Intraluminal pressures remain above baseline,
and blood flow is reduced for the entire period of observation. 11
In, our study, inferior mesenteric artery blood flow
in greyhound dogs was measured before, during
and after insufflation of the colon with RA and
CO 2 under conditions of transient and constant
Blood Flow (Percent of Control)
140
120
100
80
60
40
20
IMA Blood Flow
Intracolonic Pressure
Baseline
Pressure (4mmHg)
0
1 2 3 4 5 6 7 8 9 10
0
Time in Minutes
Figure 3. Simultaneous display of inferior mesenteric artery blood flow
and colonic intraluminal pressure following transient elevation of pressure
to 35 mmHg with CO 2 Intraluminal pressures rapidly return to baseling,
and blood flow is increased above control values. 11
5
35
30
25
20
15
10
5
0
35
30
25
20
15
10
Pressure (mmHg)
Pressure (mmHg)

elevations of intraluminal pressures. 11 Intraluminal
pressures remained elevated for briefer periods
after CO 2 administration and blood flow was far
less compromised than with RA. Baseline pressure
was reached >30 minutes after transient elevation
of intraluminal pressure to 35 mmHg with RA, and
blood flow was reduced for the entire period of
observation (Figure 2). When CO 2 was used to reach
the same levels of intraluminal pressure, blood flow
was increased above control values and baseline
pressure was attained in 6 cm compared with only 4% in the CO 2 group.
# of Patients
Residual Gas, Post-procedure 1 hr (Air vs. CO 2 )
Figure 5. Observations on post-colonoscopy abdominal pain showed
that 1 hour after colonoscopy, most patients insufflated with room air had
significant residual gas. Data from this study showed that 94% of patients
insufflated with CO 2 had only trace to minimal gas. 13
End-tidal CO 2 (kPa)
6.0
5.8
5.6
5.4
5.2
5.0
Before
exam
Caecum Rectum
CO 2 group
Air group
After
exam
CO 2
Air
Ninety-four percent of patients insufflated with
CO 2 had minimal residual gas compared with 2%
in subjects given RA. Of patients insufflated with
RA, 45% and 31% had pain at 1 and 6 hours
respectively, whereas 7% and 9% of those in whom
CO 2 was used had pain at the same time periods.
In a study by Bretthauer et al, no rise in end-tidal
pCO 2 , a non-invasive parameter of arterial pCO 2 ,
was observed in routinely unsedated patients who
were given CO 2 , although patients with severe heart
Figure 6. End-tidal CO 2 before and after colonoscopy. 14

or lung disease were excluded from the study (Figure
6). 14 Patients in the CO 2 group also had significantly
less pain for up to 6 hours after the procedure, as
evaluated by a visual analog scale (Figure 7). In a
follow-up study, Bretthauer and colleagues showed
that CO 2 insufflation is also safe in sedated patients
without significant difference between patients in
whom RA or CO 2 was used. 15
Mean VAS score (mm)
35
30
25
20
15
10
5
0
During
exam
CO 2 group
Air group
1 h 3 h 6 h 24 h
Figure 7. Plain scores before and after colonoscopy. 14
Carbon Dioxide Administration
Carbon dioxide itself is fairly inexpensive. A
1350-liter tank costs about $10-20 and can be
used for ~675 minutes of procedure time. There
are two methods of insufflation; manual and
automated. The manual method involves using
a simple regulatory connection at a minimal cost.
Some disadvantages to this method are that the
system must be assembled on site, requires close
monitoring and lacks certain safety and gas-saving
features. In addition, pressures must be set by hand.
The CO 2 EFFICIENT Endoscopic Insufflator (E-Z-
EM, Inc. Lake Success, NY) is a fully automated
system that offers several advantages over manual
insufflation. Carbon dioxide volumes are digitally
displayed. The system features two flow modes and
redundant pressure relief valves to protect against
over-inflation. In our experience, the CO 2 EFFICIENT
insufflator is simple to use and potentially safer than
the manual system.
© 2008 Bracco Diagnostics Inc. All rights reserved.
Instructions for use are available at
www.bracco.com
Conclusion
Carbon dioxide offers several advantages over
room air, including; lack of combustibility, rapid
absorption and vasodilating effects. These benefits
help to ensure a more comfortable examination
for the patient. Because CO 2 is rapidly absorbed,
there is no need to aspirate gas upon withdrawal.
The CO 2 EFFICIENT Endoscopic Insufflator is a fully
automated system that has benefits over a manual
system due to its many safety features and easeof-use.
References:
1. Rogers BHG. Gastrointest Endos 1974; 20:115-117.
2. Ben-Sousson E, et al. Eur J Gastroenterol Hepatol 2004; 12:1315-1318.
3. Grant DS, Bartram CI. Brit J Radiol 1966; 59:190-191.
4. Hussein AMJ, et al. Gastrointest Endos 1984; 30:68-70.
5. Coblentz C, et al. Clin Invest Med 1985; 8:A101.
6. Bretthauer M, et al. Gastrointest Endos 2003; 58(2):203-206.
7. Boley SJ, et al. Am J Surg 1969; 117:228-234.
8. Kozarek RA, et al. Gastroenterol 1980; 78:7-14.
9. Daugherty RM Jr, et al. Am J Physiol 1967; 213:1102-1110.
10. Sidky MS, Bean JW. Am J Physiol 1951; 167:413-425.
11. Brandt LJ, et al. Gastrointest Endos 1986; 32:324-329.
12. Duling BR. Circ Res 1973; 32:370-376.
13. Sumanac K, et al. Gastrointest Endos 2002; 56:190-194.
14. Bretthauer M, et al. Gut 2002; 50:604-607.
15. Bretthauer M, et al. Endoscopy 2005; 37:706-709.
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