Inflating Characteristics of Swan-Ganz Catheter Balloons: Clinical ...

Inflating Characteristics of Swan-Ganz Catheter Balloons:
Clinical Considerations
Jean Francois Hardy, MD, and Jean Taillefer, MD
The dangers associated with overdistension of bal-
loon-tipped pulmonary arterial catheters are well
known. A patient was brought to the operating room
for emergency coronary artery bypass graft with a
femorally inserted balloon-tipped pulmonary artery
catheter. We wondered if some form of extension tub-
ing could be used to inflate the balloon intraopera-
tively to monitor the wedge pressure because the in-
flating site is out of reach. This prompted us to
undertake the present in vitro study of the inflating
characteristics of the balloon of the pulmonary arterial
catheter and to determine if it is possible to safely use
extension tubings for these procedures.
Materials and Methods
We studied six used but not resterilized balloon-tipped
pulmonary arterial catheters (three 93A-131-7F ther-
modilution and three 93-114-7F monitoring Swan-
Ganz catheters by Edwards Corporation). Using a
standard 3-ml syringe, we inflated the balloon with
1.5 ml of room-temperature air. We determined the
critical volume of air, i.e., the volume at which max-
imal resistance was felt just before balloon inflation
began, and the diameter of the completely inflated
balloon with a Vernier scale. We repeated the mea-
surements using 32.5-cm (Cobe pressure monitoring
tubing 40-101-001) and 183-cm (Cobe pressure mon-
itoring tubing 40-10&001) rigid extension tubing fixed
to the inflating port of the balloon. We verified the
reproducibility of the measurements with a brand-
new catheter.
The internal volume of all tubings and stopcocks
was measured by fluid filling: the average internal
volume of the pulmonary arterial catheter inflating
lumen was 0.4 ml, the short extension tubing 0.8 ml,
Received from the Montreal Heart Institute, 5000 East Belanger
Street, Montreal, Quebec, Canada, HIT 1C8. Accepted for publi-
cation October 1, 1982.
Address correspondence to Dr. Taillefer.
8 1983 by the International Anesthesia Research Society
ANESTH ANALG 363
1983;62: 363-4
the long tubing 4.6 ml, and the stopcock 0.35 ml. The
volume of balloon-tipped pulmonary arterial cathe-
ters was measured by fluid immersion (Archimedes’
principle).
The pressure-volume curve of a typical catheter
was determined using an appropriately calibrated
pressure transducer (Bentley Trantec model 800).
Finally, the measured volumes were compared with
the theoretical critical volume (using Boyle’s law), the-
oretical inflating volume, and balloon volume in order
to cross-check our results.
Results
Without extension tubing, 0.75 ml of air consistently
initiated inflation of the balloon (Table 1) compared
to 1.2 2 0.1 ml with the short tubing (Table 2) and
3.25 5 0.25 ml with the long one (Table 3). The in-
flated balloon had a volume of 1.0 ml using the stan-
dard technique with the short extension set, and 1.1
ml using the long one.
Note that the critical volumes in Figure 1 are slightly
higher than those shown in the tables due to the
stopcock dead space. The inflated balloon pressure
was 275 mm Hg. Compared to the measured data,
calculated data were 0.99 ml for the inflated balloon
using the equation P,Vl = P,V,; critical pressure was
495 mm Hg with the standard inflating procedure,
496 mm Hg with the short extension tubing, and 506
Table 1. Diameter of Swan-Ganz Catheter Balloons
Obtained and Critical Volume Necessary to Initiate
Inflation Using the Standard Inflating Procedure
Type
Diameter
Swan-Ganz 1 Thermodilution 12.3 mm
2 Monitoring 12.3 mm
3 Monitoring 12.3 mm
4 Monitoring 12.5 mm
5 Thermodilution 12.1 mm
6 Thermodilution 12.3 mm
Critical
volume
0.75 ml
0.75 ml
0.75 ml
0.75 ml
0.75 ml
0.75 nil

364 ANESTH ANALG
1983;62:363-4
Table 2. Inflating Volume and Critical Volume Using a
32.5-cm Extension Tube
~~
Diameter with
Inflating Critical standard
volume volume inflation
Swan-Ganz 1 1.8 ml 1.3 ml 11.3 mm
2 1.7 ml 1.1 ml 11.8 mm
3 1.7 ml 1.1 ml 11.5 mm
4 1.7 ml 1.1 ml 11.5 mm
5 1.7 ml 1.1 ml 11.7 mm
6 1.7 ml 1.2 ml 11.3 mm
Last column is the diameter obtained with an inflating volume of 1.5 ml.
mm Hg with the long one. The theoretical volume
required to inflate the balloon to its normal 0.99-ml
capacity at 275 mm Hg is 1.8 ml with the short ex-
tension and 3.17 ml with the long one. The internal
volume of the extension set at which the inflation
volume is equal to the critical volume was calculated
at 4.16 ml.
Discussion
The diameters obtained using the standard inflation
technique were quite uniform (12.2 5 0.2 mm) and
comparable to the specifications listed in the manu-
facturer’s leaflet (13 mm) (1); we were impressed with
the high reproducibility of the measurements.
Very high pressures are necessary to initiate the
inflation of the balloon (k 500 mm Hg). When the
inflation is completed the pressure inside the balloon
drops to 275 mm Hg, which is in accordance with
previous reports (2,3), but to our knowledge these
high inflation pressures have not been reported before.
When the short extension set is used, the critical
volume is reasonably less than the inflating volume.
The measured and the calculated inflating volumes
Table 3. Inflating Volume and Critical Volume Using a
183-cm Extension Tube
Inflating Critical
volume volume
Swan-Ganz 1 3.3 ml 3.0 ml
2 3.5 ml 3.4 ml
3 3.5 ml 3.3 ml
4 3.5 ml 3.3 ml
5 3.5 ml 3.5 ml
6 3:5 ml 3.5 mi
Diameter with
standard
inflation
8F
8F
8F
8F
8F
8F
mmHg
500 1
CLINICAL REPORTS
PRESSURE - VOLUME CURVE VARIATION
ACCORDING TO THREE DIFFERENT TUBING LENGTHS
joow
:/
, I , ,
/
0
0 1 2 3 4 cm3
Figure 1. Pressure-volume curve variation using three different
lengths of tubing.
are identical. However, when using the long exten-
sion set, the critical volume is usually equal or slightly
less than the inflation volume. Furthermore, the cal-
culated inflation volume is smaller than the measured
critical volume meaning that overinflation is inevitable.
We can draw three conclusions from the data.
1. Physicians using balloon-tipped pulmonary arterial
catheters must realize that they can generate
very high pressures (2500 mm Hg) with the simple
compression of 1.5 ml of air. These can lead to
serious complications if the catheter is, for example,
in a permanent wedge position.
2. Short extension tubings with low internal volume
may be used safely, and standard inflating volumes
produce a clinically acceptable inflation.
Should one wish to obtain full inflation of the balloon,
the specific tubings must be tested before use
in a clinical situation.
3. Long extension tubings should not be used as
overinflation is unavoidable.
We thank Dr. Martin Morissette for his editorial review and Mrs.
Leila Geadah and Ginette Bleau for their secretarial assistance.
References
1. Swan-Ganz flow directed monitoring catheters, package insert.
Edwards Laboratories. Ref. 108328 3 Rev. B.
2. Barash PG, Nardi D, Hammond G. Catheter induced pulmonary
artery perforation-mechanisms, management, and modifica-
tion. J Thorac Cardiovasc Surg 1981;82:5-12.
3. Eisenkraft JB, Eger I1 EI. Nitrous oxide and Swan-Ganz cathe-
ters. Anesth Analg 1982;61:308-9.