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CASE REPORT  |   December 1995
Placement of a Right Atrial Air Aspiration Catheter Guided by Transesophageal Echocardiography
Article Information
Cardiovascular Anesthesia / Radiological and Other Imaging / Respiratory System / Technology / Equipment / Monitoring
CASE REPORT   |   December 1995
Placement of a Right Atrial Air Aspiration Catheter Guided by Transesophageal Echocardiography
Anesthesiology 12 1995, Vol.83, 1359-1361. doi:
Anesthesiology 12 1995, Vol.83, 1359-1361. doi:
ONE of the principal risks of the sitting position for neurosurgical patients is the possibility of life-threatening air embolism. Use of a multiorificed central venous catheter is highly recommended as a means for aspirating air from the circulation should embolism occur. 1The junction of the superior vena cava (SVC) and right atrium (RA) is the optimal position for maximal efficacy in aspirating air. 2Conventional methods for placement of the catheter include the use of x-ray, fluoroscopy, or pressure waveform monitoring. These methods are time consuming, require additional personnel, and may not precisely localize the catheter at the RA-SVC junction. In addition, chest x-ray and fluoroscopy may expose personnel to radiation. Accordingly, the catheter is typically placed by interposing a stopcock with a metal connector into the fluid path of the catheter and connecting the stopcock to an ECG machine. The P wave is transduced as the catheter is advanced through the SVC. The point at which the P wave changes direction is the RA-SVC junction. Because we were not able to locate the metal stopcock that we usually used for this procedure, and transesophageal echocardiography (TEE) was available in our operating room, we used TEE to guide the proper placement of the catheter.
Case Report
The patient, a 38-yr-old man, was scheduled for resection of an acoustic neuroma to be performed with the patient in the sitting position. After induction of general anesthesia and tracheal intubation, a 5-mHz omniplane TEE probe (Hewlett-Packard, Andover, MA) was inserted, and a Hewlett-Packard Sonos 1500 OR echocardiography machine was used to obtain views of the heart. First, the patient was evaluated for the presence of a patent foramen ovale by imaging the intraatrial septum. Color flow imaging and hand-agitated saline injections with and without sustained continuous positive airway pressure (5–10 mmHg) did not reveal a right-to-left intraatrial shunt. Next, a Bunegin-Albin multiorificed air aspiration catheter (CVAE-580; Cook Critical Care, Inc., Bloomington, IN) was sterilely placed via the left subclavian vein, and advanced until its position in the midright atrium was visible in a short-axis view at the base of the heart. The catheter was withdrawn to the RA-SVC junction. To provide additional confirmation of proper catheter placement, hand-agitated saline microbubbles were flushed through the catheter. Microbubbles were produced by forcibly injecting approximately 10 ml of a blood-saline mixture alternately for about 1 min between two syringes connected by a stopcock. Any macroscopic air bubbles were discharged before injection of the mixture into the catheter. This contrast material could be visualized as it left the catheter and entered the RA (1). We then secured the catheter in place, and the operation proceeded uneventfully without the occurrence of significant air embolism.

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Discussion
Transesophageal echocardiography has been used in both children and adults to guide the proper placement of pulmonary artery catheters. 3-4The tip of the catheter and the balloon were visible during advancement into the pulmonary artery. 5Transesophageal echocardiography has also been used to localize the tip of a ventriculoatrial shunt. 6In our case, it was easy to visualize the RA-SVC junction, the ideal site for placement of the air-aspiration catheter. Flushing saline microbubbles through the catheter confirmed its correct positioning. Our method is advantageous when a TEE machine is readily available, and it eliminates the need for x-ray equipment. Although not confirmed by our case, our belief is that, if the TEE probe is positioned properly, this method is as efficient as placing the catheter using ECG monitoring. A theoretic advantage of placement guided by TEE rather than ECG is that ECG changes may be recorded not from the tip, but, rather, from the more proximally located lumen orifices; therefore, the tip may not truly be at the RA-SVC junction. 7.
Limitations of using TEE are: 1) settings for gain and ultrasound transmission must be adjusted properly, and 2) the operator must be experienced in recognizing the anatomic correlations and structures of the heart and great vessels. When contrast injection is used to localize the catheter, contrast may flow from both the catheter tip and proximal orifices; this flow may decrease its usefulness for locating the tip of the catheter. In summary, we believe that this method is an efficient means for placing the air aspiration catheter when an ultrasound system is available. This example is another potential application of intraoperative echocardiography by the anesthesiologist.
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