Along with writing in various genres (including medical books, slide kits, and multimedia), Dr. Cauwels' instructional design experience/capabilities include
• faculty and medical school lectures
• university teaching of literature and writing
• training programs
• project creation/management
• proactive improvements in efficiency and morale
• involvement in other educational activities
• use of sales training materials to prepare for her insurance licensing examination.
• Direction of 18-month project outlining comprehensive procedural descriptions for engineering product development at Control Data Corporation
• Survey analysts/auditors
• Clerical workers
• Sonar/video device owners
• Sales managers
• Training video on proper chemical handling
• Video on patient simulator
• Disks and support materials for Apple, ATARI, Texas Instruments computers (copy and art editing for three months onsite)
• Sales training test questions on daclizumab
• Revision of moderator guidelines for h. pylori presentation
• Hemodialysis Access: Integrated Clinical Strategies for Maintaining Patency, an educational booklet for physicians and sales representatives
[Illustration of Hydrolyser]
PMT devices are currently approved only for treatment of hemodialysis grafts (6, 13).
Having already performed a diagnostic venogram, exchange the angiographic catheter for a vascular sheath of appropriate size. All PMT devices require use of a vascular sheath, most of them a 6 Fr sheath. Some practitioners prefer sheaths that are only 5 to 7 cm long to decrease the amount of plastic within the graft, however, while others use longer sheaths to keep their hands out of the field.
Advance the PMT device through the sheath into the graft and activate it to remove thrombus from the entire venous limb. Once the venous limb is clear of thrombus, place the second access within it, a few centimeters away from the venous anastomosis and pointing toward the arterial side. Advance the PMT device through the sheath in the second access up to the arterial anastomosis, but do not cross it. Activate the device to clear the entire arterial limb of thrombus. If desired, intermittently inject dilute contrast material through the sideport of the vascular sheath to visualize the extent of residual thrombus.
After macerating or homogenizing the thrombus, aspirate the retained thrombotic material. The professional literature describes methods of doing so through the sidearm of the sheath if the PMT device itself does not aspirate.
Venous Stenosis Treatment
Stenosis resolution rather than clot removal appears most strongly to influence long-term outcomes of thrombectomy procedures. Following thrombus removal, proceed with the venous angioplasty. If it has not yet been done, cross the venous anastomisis. Advance the PTA catheter across the venous anastomosis and position it appropriately to treat any accessible lesions.
Following angioplasty, slowly inject contrast to check for residual stenosis and for any intragraft stenosis. If necessary, perform additional angioplasty at the venous anastomosis or on intragraft stenoses using access from either of the two sheaths.
Arterial Plug Dislodgement
[Illustration of inflated Fogarty balloon pulling back the clot]
The arterial plug is a compact, rubbery thrombus found at the arterial anastomosis in all clotted dialysis grafts. Composed of compressed, laminated layers of fibrin and erythrocytes, it does not respond to thrombolysis and must always be mechanically macerated or removed (6).
Although the arterial plug may be treated with the PMT device, generally it is dislodged using any of the following catheters: standard Fogarty, Thru-Lumen (over-the-wire) Fogarty, Fogarty Adherent Clot Catheter, balloon occlusion catheter, or conventional angioplasty balloon.
Despite its cost-effectiveness, use of a conventional balloon is not recommended for this purpose because it is likely to dislodge clot into the artery. Most practitioners use a Fogarty balloon, an atraumatic, flexible balloon whose compliance allows it to conform to the shape of a graft or artery, in which it can pull or push a clot. It can be inflated with saline (with or without contrast solution) or with air to provide additional compliance.
Carefully advance the Fogarty catheter across the arterial anastomosis, inflate it gently under fluoroscopic observation, and pull it back across the anastomosis and into the graft. This process may need to be repeated several times to dislodge and completely remove the plug. Typically the plug needs to be further macerated with the PMT device or the angioplasty balloon before being pushed into the central veins and ultimately carried to the lungs for autolysing by the body’s natural mechanisms.
Readvance the Fogarty balloon or a diagnostic catheter into the artery. Perform a limited arteriogram to assess the anastomotic area and check for distal embolization of thrombotic material. Use a final fistulogram to evaluate and document the results.
Remove the vascular sheaths and guidewire. Thrombotic material that may be caught up against them will usually wash away (13).
More samples of medical writing appear on the Medical Communications and Other Books pages.
Excerpt from User's Manual for Video Sounders
Interpreting the Graph
The top light on the sounder graph at "0" represents the water surface, and the lower light indicates the bottom. The sounder shows a light blip at the depth of an object that is proportional to its size.
An advantage of the sounder is that it records individual fish as arches that distinguish them from their stationary surroundings. Fish appear as arches because the sound waves must travel different distances as a fish moves from one edge of the sound cone to the other, as shown in Figures 12 and 13.
For the same reason, a fish swimming in and out of the cone edge, or one swimming in a circle within the cone, appears as a straight line.
A school of bait fish or minnows, usually near the surface, returns several thin signals.
Large echoes beneath them are game fish that often swim below the smaller fish to feed on them, as shown in Figure 14.
When watching the sounder graph, you need to remember these points:
• The graph suggests that all information displayed is directly under the boat, as shown in Figure 15.
This distortion occurs because the unit compresses all objects within the sound cone into a single narrow line that is easy to imagine as vertical. Remember that the edges of the sounding field actually form an inverted cone.
• The boat's speed does not affect the rate at which objects appear on the graph.
To understand this better, imagine a tall, long-legged man walking along a beach and leaving footprints in the sand. Suppose that this man begins at a specific landmark and takes exactly 25 strides. Now suppose that the man returns to the landmark and takes 25 running steps alongside his original set of footprints.
The running footprints will be farther apart and cover greater distance than the walking footprints. But the number of footprints (25) remains constant, and all the prints are recorded in the sand, although at different speeds.
The same is true for the echoes on a sounder. All echoes are recorded even though the speed, and therefore the space between the echoes, can vary.
Boat speed can distort echoes only when the bottom suddenly drops, because time passes before the sounder picks up the second (lower) echo.
• Objects on the video screen do not "come and go."
Any image on the screen remains there until it moves off the left side.
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