To the Editor:—
The use of transesophageal echocardiography (TEE) in the operating room, both for cardiac and noncardiac surgery, is increasing. In our hospital, we use disposable sheaths over the TEE-probe, to prevent nosocomial infections 1,2. Placing a Latex sheath over the TEE-probe in the operating room is not easy; it is time-consuming and the limited space can necessitate bending of the probe, which may decrease its longevity. Polyurethane sheaths are even more difficult to place over the probe. Potentially life-threatening allergic reactions to Latex have forced us to consider the use of polyurethane sheaths. 3,4
In order to maximize the ease of sheath placement, we have designed a vacuum tube, mounted on the echo-machine. This consists of two Perspex or Polycarbonate tubes (Polycarbonate exhibits extremely high-impact strength); a smaller tube within a larger tube (Fig. 1). Holes are placed in the inner tube and vacuum is applied between the inner and outer tubes. The exact placement of the holes in the inner tube is crucial; they have been placed, after trial and error, at the section of the inner tube that coincides with the distal 60–80% of the probe, and also at the bottom of the inner tube. After placing the sheath and applying negative pressure, the sheath opens against the wall of the inner tube; starting proximally and extending distally. Once the distal part of the inner tube has been reached, the sheath closes the openings in the inner tube, and the suction force from the holes in the bottom of the inner tube now extends its length (the length of the probe extends a few cm from the last distal opening in the tube). Ultrasound gel is placed on the tip of the probe so that it can be effortlessly placed in the stretched sheath. After removing the negative pressure, the distal part of the sheath retracts first (the proximal side-holes are still occluded by the sheath), thereby fitting tightly around the tip of the probe. The remaining negative pressure is then reduced so that the rest of the sheath retracts around the shaft of the probe. Occasionally, minimal manipulation of the tip of the sheathed probe is needed in order to remove air (the fit of the polyurethane sheath is extremely tight and, in fact, much better). This procedure is quick, easy, and clean, and requires minimal manipulation of the probe. Readers may be interested in this “self-moving” method, which can quite easily be locally manufactured.