Aneurysm sac pressure monitoring: does the direction of pressure measurement matter in fibrinous thrombus?
OBJECTIVE
This study was conducted to clarify the effect of the direction of pressure measurement on the pressure readout in fibrinous thrombus of the abdominal aortic aneurysm.


METHODS
Three weights of 468 g (weight 1), 578 g (weight 2), and 675 g (weight 3) were molded. A specimen of human fibrinous thrombus was positioned under the weights. Because the surface area of the weights and the thrombus was 400 mm(2), weights 1, 2, and 3 caused pressures of 88, 108, and 127 mm Hg, respectively. Pressure measurements were performed at different angles between the sensor and the applied force (0 degrees , 22.5 degrees , 30 degrees , 45 degrees , 60 degrees , 67.5 degrees , 90 degrees ) Thrombi of 10 different patients were analyzed. Pressure measurements in the thrombi at different angles were statistically compared by a linear mixed model analysis.


RESULTS
The measurements at 90 degrees differed statistically from the measurements at 0 degrees , 22.5 degrees , 30 degrees , 45 degrees , 60 degrees , and 67.5 degrees (P < .001). The pressure readout was only similar to the applied pressure when the pressure sensor was positioned at 90 degrees to the applied force. Pressure measurements in other sensor positions resulted in lower pressure measurements. Pressure changes were detected in all sensor positions. There appeared to be no significant difference between the pressure measurements taken at same angles in the 10 thrombi (P > .05).


CONCLUSIONS
In fibrinous thrombus of abdominal aortic aneurysm, the direction of pressure measurement influenced the pressure readout.
Hinnen
Jan-Willem
JW
Department of Surgery, Division of Vascular Surgery, Leiden University Medical Center, Leiden, The Netherlands. j.w.hinnen@lumc.nl <j.w.hinnen@lumc.nl>
Rixen
Daniel J
DJ
Koning
Olivier H
OH
Van Bockel
Hajo J
HJ
Hamming
Jaap F
JF
D017544:Aortic Aneurysm, Abdominal / Q000378:metabolism / Q000503:physiopathology* / Q000601:surgery; D001019:Aortic Rupture / Q000378:metabolism / Q000503:physiopathology*; D001794:Blood Pressure; D001795:Blood Pressure Determination / Q000295:instrumentation / Q000379:methods*; D005337:Fibrin / Q000378:metabolism*; D006801:Humans; D016014:Linear Models; D013927:Thrombosis / Q000378:metabolism / Q000503:physiopathology* / Q000601:surgery; D014160:Transducers, Pressure
D005337:Fibrin