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J Thorac Cardiovasc Surg 1995;109:1244-1246
© 1995 Mosby, Inc.
BRIEF COMMUNICATIONS |
Rapid City, S.D.
From the Cardiac Vascular and Thoracic Surgery P.C., 350 Elk St., Suite B, Rapid City, S.D.
Paraplegia is a devastating complication after thoracoabdominal aneurysm resection. Multiple methods of spinal protection have been explored. 
1-9 At present, no reliable method of protecting the spine from ischemic injury exists. I am describing here two cases of thoraco abdominal aneurysm resection with selective cooling of the spinal cord. While the aorta was crossclamped, continuous lavage of the spinal cord with cold normal saline solution was introduced into the subarachnoid space by lumbar puncture. No neurologic sequela developed after crossclamping of the aorta for 58 minutes in case 1 and 36 minutes in case 2.
Case 1
A 72-year-old woman was referred to me with a symptomatic thoracoabdominal aneurysm. Angiography showed a large arteriosclerotic aneurysm originating in the distal aortic arch, propagating throughout the thoracic aorta, and involving most of the abdominal aorta below the renal arteries. Spinal cord protection protocol was approved by the Institutional Review Committee of the Rapid City Regional Hospital.
On the day of the operation, the patient was taken first to the angio suite for placement of catheters to the subarachnoid space. The procedure was performed with the patient under heavy sedation by an invasive radiologist. The patient was placed prone on a fluoroscopic table with tilt capabilities. The subarachnoid space was entered at the L2-3 level with midline stick with a 20-gauge spinal needle (Fig. 1). The Cook micropuncture system guidewire (Cook Incorporated, Bloomington, Ind.) was then placed through the spinal needle into the subarachnoid space and advanced upward in the midline. After the dilating catheter was positioned ventral within the subarachnoid space, the 0.035 Tad II wire with 0.018 tip (Advanced Cardiovascular Systems, Inc., Santa Clara, Calif.) was passed. The Tad wire is steerable and the 0.018 tip helped avoid damage to nerve roots or cord while the wire was being advanced. The Tad wire was positioned above T5 ventral to the spinal cord. A 5F straight flush catheter was placed over the wire and positioned above T5. By means of the procedure just described, the second 5F catheter was placed at the level of the conus medullaris. The catheter should have four to five additional side holes placed at its tip. The entrance into the subarachnoid space for this second catheter should be, if possible, one level below the entrance of the first catheter. The third catheter was placed at the next inferior level with the tip placed in the lumbar region. This catheter can be 4F flush without any additional side holes. Catheters were sutured to the skin and covered by a Tegaderm transdermal patch (3M Health Care, St. Paul, Minn). The superior-most catheter was used as the infusion catheter; the second catheter at the level of the conus medullaris was the effusion catheter. The 4F catheter was the pressure-monitoring catheter. The patient was transported to the operating room.
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Shortly before the aorta was crossclamped, the cooling process began. The cooling system consisted of the following elements: (1) a Bentley BCR 3000/Baxter reservoir (Bentley Laboratories Division, Irvine, Calif.) containing normal saline solution; (2) a roller pump—Sarns model S10K2 blood pump (Sarns Inc., Ann Arbor, Mich); (3) a heat exchanger, which is a MYOtherm 41 Avecor cardioplegia delivery system (Avecor Cardiovascular Inc., Plymouth, Minn.). A CSZ Hemotherm cooler heater model No. 400M (Cincinnati Sub-Zero Products, Inc., Cincinnati, Ohio). The tubing for the drainage is a Medtronic cardioplegia delivery line (Medtronic, Inc., Minneapolis, Minn.) (Fig. 1).
The temperature of the coolant right before entering the subarachnoid space was 6° C. The temperature of the draining solution was maintained at 20° to 22° C with a delivery speed of 15 to 20 ml/min, which corresponded to a spinal fluid pressure of no higher than 15 cm H2O.
The draining solution was discarded. The tubing sizes were 5F inflow/outflow and 4F pressure.
A 4000 unit dose of heparin was given intravenously. Once the temperature of the draining solution reached 20° C, the aorta was crossclamped immediately distal to the takeoff of the left subclavian artery. A No. 20 Dacron graft was selected and an end-to-end anastomosis was constructed. The intercostal vessels above the T5 level were oversewn. The intercostal vessels below the T5 level, celiac access, superior mesenteric artery, and renal arteries were incorporated into the graft. A distal anastomosis was placed in the abdominal aorta above the bifurcation. After the flow through the graft was restored, the cooling was discontinued. The systemic temperature remained normothermic throughout the procedure. Catheters from the subarachnoid space were discontinued the following day. The patient recovered uneventfully, was extubated the following day without any neurologic complications, and was discharged 9 days later.
Case 2
A 65-year-old woman also had a symptomatic thoracoabdominal aneurysm. The aneurysm was originating in the lower thoracic aorta. An angiogram showed that the origin of the aneurysm proximally was about 1 inch above the celiac access. It propagated throughout the abdominal aorta involving the entire abdominal segment. The proximal iliac arteries were ectatic but not truly aneurysmal. The protocol for spinal protection was exactly the same as in case 1, although the operative procedure was obviously less extensive.
A thoracoabdominal incision was used through the eighth intercostal space. The aorta was crossclamped about 2 inches above the diaphragm. One pair of intercostals, celiac access, superior mesenteric artery, and renal arteries were incorporated as one island to the graft. The anastomosis distally was placed right at the bifurcation of the aorta. The patient recovered from the operation without any complications.
CONCLUSION
Selective cooling of the spinal cord with continuous lavage of cold normal saline solution demonstrates several important points:
Although it is too soon to draw any conclusions regarding the effectiveness of this method of spinal protection, I believe that further clinical studies should be done The results of the animal experiments have been encouraging. 1,2
ADDENDUM
Since this manuscript was accepted for publication, this method of spinal protection has been used in two more patients requiring resection of arteriosclerotic thoracoabdominal aneurysm. The first patient was a 74-year-old man with a contained rupture of a thoracoabdominal aneurysm originating at the takeoff of the left subclavian artery down to the infrarenal aorta, where a graft had previously been placed for an abdominal aortic aneurysm. The crossclamp time was 46 minutes. The second patient was a 71-year-old man, also with a history of previously resected abdominal aortic aneurysm, who presented with a large asymptomatic thoracoabdominal aneurysm. The aneurysm involved the entire descending thoracic aorta and terminated right below the diaphragm. The aorta was crossclamped for 50 minutes. Both patients did well without any neurologic complications.
Footnotes
J THORAC CARDIOVASC SURG 1995;109:1244-6 
References
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