Spinal Fluid Drainage Problems Can Be Prevented

SAN DIEGO -- Spinal fluid drainage is a standard intervention to reduce the risk of paraplegia in thoracic and thoracoabdominal aortic aneurysm repair. Strategies to reduce the volume of spinal fluid drained while still controlling spinal fluid pressure appear able to eliminate serious complications from the treatment, according to a study of patients treated over the past 2 decades.

The study was presented at the Vascular Annual Meeting by Dr. Matthew Mell of the University of Wisconsin, Madison.

Database analysis was performed for 648 patients who had thoracic aortic aneurysm repair (TAA) or thoracoabdominal aortic aneurysm repair (TAAA) over the period from 1987 to 2008. Patients with thoracic aneurysms were treated with endografts since 2005. The mean age of patients was 67, and 54% were men.

Spinal drains were used in a 486 (75%) of the patients. Spinal fluid pressure (SFP) was reduced to less than 6 mm Hg during thoracic aortic occlusion and reperfusion, and kept less than 10 mm Hg until patients were awake with normal leg lift. Until 2000 a 19-gauge epidural catheter was used; from 2001 a 16-gauge silastic drain placed under fluoroscopy has been used, with needle insertion at L3-4 or L2-3 with the catheter tip positioned at T9-10. Drains were removed 48 hours after surgery and spinal and head CTs were performed in patients with bloody spinal fluid during or after surgery, according to Dr. Mell and his colleagues.

A small number of serious complications were seen. Bloody spinal fluid occurred in 25 patients (5.1%). Of these, 7 had no CT evidence of intracranial hemorrhage, 14 had intracranial blood without neurologic deficit, and 4 patients had significant intracranial bleeding with neurologic deficits. Among these 4 patients, 1 died from brain herniation, 2 had permanent deficits, and 1 recovered fully. This placed the incidence of serious complications directly resulting from spinal fluid drainage (SFD) at 0.8% and mortality from drain complications at 0.2%.

Three of the four patients with neurologic deficits had cerebral atrophy with evidence of old subdural hematoma, leading Dr. Mell and his colleagues to conclude that cerebral atrophy or chronic subdural hematoma should be considered an increased risk for complication from SFD in these operations.

Univariate and multivariate analyses showed that amount of fluid drained (mean 124 mL vs. 178 mL, P less than .0001) was significantly correlated with intracranial bleeding. Age, sex, blood pressure, drain type, SFP, change in SFP, acuity, and Crawford aneurysm type were not significantly correlated with bleeding.

Other complications included two epidural catheter and four silastic drain patients with spinal fluid leak and headache that required treatment with an epidural blood patch. There were no spinal hematomas.

"Using strategies to reduce the volume of SFD but still control SFP, we have eliminated serious complications for the last 4 years," Dr. Mell concluded.

The researchers stated that they had no conflicts of interest to disclose regarding this presentation.

When asked to comment on this story, Dr. Ronald Fairman, professor of surgery and chief of the division of vascular surgery and endovascular therapy at the University of Pennsylvania, Philadelphia, stated: "This is a comprehensive experience of lessons learned using spinal fluid drainage over 30 years." The authors performed thoracic endovascular aortic repair (TEVAR) for thoracic aneurysms during the last 3 years of their series. Guidelines and indications for SFD in the setting of TEVAR are not well established. While some centers have adopted the same indications and procedures for SFD as in the open thoracic aortic patients, other centers have used a more selective pathway including variables such as extent of thoracic aortic coverage and number of implanted devices. It has been recognized that the left subclavian artery is an important source of collateral blood flow to the cord and revascularization rather than coverage may be indicated at least in the elective setting, Dr. Fairman noted. Dr. Mell's recommendations will no doubt remain highly relevant in the current era of TEVAR, he concluded. Dr. Fairman is also an associate medical editor of Vascular Specialist