Eur J Cardiothorac Surg 2004;25:139-141
© 2004 Elsevier Science NL
Safety and efficacy of epidural cooling for regional spinal cord hypothermia during thoracoabdominal aneurysm repair
N. Motoyoshi*,
G. Takahashi,
M. Sakurai,
K. Tabayashi
Department of Cardiovascular Surgery, Tohoku University, 1-1 Seiryou-cho, Aoba-ward, Sendai 981-0824, Japan
Received 17 November 2002;
received in revised form 25 July 2003;
accepted 1 September 2003.
* Corresponding author. Tel.: +81-22-717-7111; fax: +81-22-717-7117
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Abstract
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Twenty-four consecutive patients underwent epidural cooling as an adjunct to elective thoracoabdominal aortic repair under moderate systemic hypothermia. One patient suffered from postoperative paraplegia (4%), and another died from subarachnoidal hemorrhage (4%). Details of the technique, the associated care, and the pitfalls will be discussed.
Key Words: Epidural cooling • Thoracoabdominal aortic aneurysm
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1. Introduction
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In the repair of thoracoabdominal aortic aneurysm, the clinical outcomes have been improved, but mortality and morbidity remain high in certain situations. Various adjuncts against spinal cord injury have been performed including epidural cooling (EC) which reported an experimental model [1–5]. Cambria and Davison et al. reported their clinical results [3,6]. However, little is known about the management of EC. The purpose of the present report is to introduce the technique and discuss the care that should be taken in its applications.
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2. Patients and methods
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Between January 1998 and April 2002, 24 consecutive patients with thoracoabdominal aortic aneurysm underwent elective operation with epidural cooling. The patients’ characteristics are shown in Table 1.
2.1. Operation
The common femoral artery and vein were exposed, and the femoral artery was cannulated with an 18–22-F short cannulae. A 21–25-F long cannula was inserted into the femoral vein and positioned in the right atrium. The thoracoabdominal aorta was exposed through a left spiral incision. Cardiopulmonary bypass was established after the chest was entered. Moderate hypothermic operations (31–32 °C) were employed. Then the aneurysm was full-opened and the inlets of critical intercostal arteries were cannulated for hemostasis using small sized occlusive catheter. The other vessels, which were small and not located on the fragile area (T9–L2) were oversewn. Staged aortic cross-clamping was standard in cases with long segmental aneurysm such as Crawford type I and II. Visceral shunting, reimplantation of two to three pairs of intercostal and lumber arteries within T9–L2, and cerebrospinal fluid (CSF) drainage (Fig. 1)
were also standard. Then, rewarming was started. Visceral vessels were reattached using small side-arm grafts. The distal anastomosis was performed thereafter.
2.2. Epidural cooling
The epidural catheter (16–17 gauge Medicut, UK-?, Catheter kit, Argyle®) was inserted through T11–12 intrathecal space, and advanced in the cranial direction at T11 according to X-ray verifications on the day before operation. The catheter was connected to cold saline transfusion pump (Terufusion Blood transfusion pump, BP-101, TERUMO®, Tokyo, Japan) (Fig. 1). Cold saline infusion was started at 3–5 ml/min 30 min before aortic cross-clamping, and maintained at 0–7 ml/min. CSF pressure was checked every 5 min. The perfusion was terminated after the reattachment of the critical segmental arteries was completed. Spinal cord perfusion pressure (equal to mean arterial pressure minus cerebrospinal fluid pressure) was kept above 50 mmHg.
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3. Results
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Operative data and postoperative state are shown in Table 1. One patient with atheromatous aneurysm (Crawford type III) died of postoperative subarachnoidal hemorrhage. The remaining patients survived. Another patient (Crawford type II) who demonstrated high CSF pressure during epidural cooling and severe hypotension during and after aortic cross-clamp, complicated paraplegia.
Epidural cooling catheter incision was successful in all patients. CSF temperature revealed a mean of 24.3±2.2 (range, 22.0–28.5 °C) during aortic cross-clamping with core temperature of 30.9±0.8. Maintenance of regional hypothermia was easily obtained by adjusting the infusion rate. Two cases exhibited high CSF pressure (55 and 60 mmHg) only for a few minutes.
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4. Discussion
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EC is a regional cooling method, the first clinical application having been reported by Davison et al. [3]. They achieved an improved clinical results of less than 3% of postoperative paraplegia, but observed that EC needs technical learning because it required assistance [6]. In some early cases, we had difficulties with handling EC safely, because excessive infusion volume will readily increase CSF pressure. Spinal neurons are supposed to be ischemic if subjected to a CSF pressure of 40 mmHg for a few hours; hits is because measurements of residual mean arterial pressure, as lower intercostal arteries were ligated (in animal preparations), revealed that there was usually no spinal cord ischemic injury if the arterial mean back pressure remained above 35 mmHg [7]. We had two cases who showed high pressure during epidural cooling. Careful attention to spinal cord perfusion pressure appears to be essential.
One patient suffered from early postoperative paraplegia. High CSF pressure appeared a few minutes in this case. Reattachment of intercostal and lumbar arteries had been sufficient. However, due to bleeding, the patient had an unstable circulatory condition after aortic cross-clamp until transfer to ICU. (We note that perioperative circulatory condition has been reported to be one of the most important risk factors for paraplegia after thoracoabdominal aortic replacement [8].) The CSF temperature was maintained at 26 °C and CSF drainage was well executed. MRI showed a focal high intensity signal at T8–L1 in the gray matter of thoracic spinal cord, which two radiologists diagnosed as an infarction signal. Another patient died from subarachnoidal hemorrhage (SAH). However, no apparent pathological correlation between SAH and EC technique was found in the postmortem study.
Previously we had experienced an 11% incidence of paraplegia and paraparesis in 40 cases who received thoracic descending or thoracoabdominal aortic repair without special adjunct (data not shown). The EC technique has clearly provided us with a better results. EC was relatively safe and almost universally successful in this trial.
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Footnotes
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Presented at the 16th Annual Meeting of the European Association for Cardio-thoracic Surgery, Monte Carlo, Monaco September 22–25, 2002.
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References
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- Kouchoukos N.T., Rokkas C.K. Hypothermic cardiopulmonary bypass for spinal cord protection: rationale and clinical results. Ann Thorac Surg 1999;67(6):1940-1942.[Abstract/Free Full Text]
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- Davison J.K., Cambria R.P., Vierra D.J., Columbia M.A., Koustas G. Epidural cooling for regional spinal cord hypothermia during thoracoabdominal aneurysm repair. J Vasc Surg 1994;20(2):304-310.[Medline]
- Tabayashi K., Niibori K., Konno H., Mohri H. Protection from post ischemic spinal cord injury by perfusion cooling of the epidural space. Ann Thorac Surg 1993;56:494-498.[Abstract]
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- Cambria R.P., Davison J.K., Carter C., Brewster D.C., Chang Y., Clark K.A., Atamian S. Epidural cooling for spinal cord protection during thoracoabdominal aneurysm repair: A five-year experience. J Vasc Surg 2000;31(6):1093-1102.[Medline]
- Killen D.A., Adkins R.B., Jr Studies of spinal arterial bed pressure following extensive mobilization of the aorta from the posterior parietes. J Thorac Cardiovasc Surg 1965;49:231-240.
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Abstract
1. Introduction
