[Detection of air embolism by a re-usable Doppler probe integrated in a central venous line--application in-vivo].
OBJECTIVE
Air embolism frequently occurs under neurosurgical operations performed in the sitting position. Recently we reported the idea of inserting a re-usable doppler probe into a blind-ending lumen of a central venous catheter (Schregel-Volk-Catheter, SVC). In vitro testing in a circulation model showed a high sensitivity: air bubbles as small as 0.5 microliter were reliably detected at a distance up to 4 cm from the tip of the SVC.


METHODS
After approval by the local ethics committee pigs were anaesthetised and a cardiopulmonary bypass was connected. During the bypass period a 12 F SVC (Medex Medical, Germany) with one blind-ending lumen was positioned into the proximal vena cava cranialis or vena cava caudalis. An 8 MHz doppler probe (MTB Basler, Suisse) was introduced into the SVC and connected with the doppler device Multi-Dop T (DWL, Germany). Well defined air bubbles (3-6 microliter) were generated by a bubble generator and injected into the right femoral vein or the left vena jugularis interna.


RESULTS
All bubbles were reliably detected by the re-usable doppler probe. Embolic events can be documented, counted and quantified by the Multi-Dop T.


CONCLUSIONS
Using SVC's with a blind-ending lumen could improve and simplify the detection of air embolism. We see several advantages (e.g. sensitivity, costs) compared with established methods (precordial doppler, TEE) for detection of air embolism.
Volk
O
O
Medizinische Klinik I, Klinikum Krefeld, Germany. o.volk@freenet.de
Schnitker
W
W
Brass
P
P
Klass
O
O
Bosse
M
M
Boerner
U
U
Fischer
J H
JH
Schregel
W
W
D000818:Animals; D002405:Catheterization, Central Venous / Q000009:adverse effects / Q000295:instrumentation*; D004618:Embolism, Air / Q000175:diagnosis* / Q000209:etiology; D006439:Hemodynamics / Q000502:physiology; D017078:Laser-Doppler Flowmetry / Q000295:instrumentation*; D013552:Swine