Preventing and Treating Paraplegia
after Thoracoabdominal Aortic Aneurysm Repair
January/February 2007
Thoracoabdominal aortic aneurysm repair is a definitive procedure – success results in a cure. Nevertheless, this procedure represents one of the most complex surgical repairs in contemporary medicine. Preventing or promptly responding to intra- and post-operative complications is the key to producing optimal outcomes.
Despite advances in surgery and anesthesia, the most serious and devastating complication is paraplegia. Blood to the spinal cord is often supplied from the diseased segment of the aorta. Spinal cord ischemia or infarction occurs when blood flow is disrupted, either during repair or in the post-operative period.
The Penn Thoracic Aortic Surgery program manages this complication by employing a team of surgeons, anesthesiologists, intensivists, cardiologists, neurologists, and critical-care nurses focused on three strategies:
- Preserving blood supply to the spinal cord,
- Improving detection of spinal cord ischemia during anesthesia and after operation, and
- Implementing emergency interventions to treat spinal cord ischemia in the event of paraplegia.
Preventing Intraoperative Paraplegia
Controlling both the arterial pressure and cerebrospinal fluid (CSF) pressure is critical in preventing spinal cord sequelae during the intraoperative period. Extracorporeal circulation with a heart-lung machine maintains blood flow distal to the aneurysm. Proximal and distal aortic blood pressure is closely monitored to maintain mean arterial pressures (MAP) above 85mm Hg.
A thin silastic catheter is inserted into the spinal canal after general anesthesia induction. Cerebrospinal fluid (CSF) is drained to maintain CSF pressure at 10 mm Hg or less to prevent impedance of spinal cord perfusion. Intraoperative somatosensory evoke potential (SEP) monitoring evaluates spinal function status. The Penn team is experiencing a significant decrease in the incidence of intraoperative paraplegia using these techniques.
Reversing Postoperative Paraplegia
Index of suspicion for paraplegia must remain high in the postoperative period. Certain patients remain at risk for delayed onset spinal cord ischemia. With this in mind, Penn created a “rapid response team.” Lumbar CSF drainage and arterial pressure augmentation remain core treatment tactics. However, the patient becomes a critical member of the team during this phase. ICU nurses and others staff members trained in recognizing spinal cord ischemia instruct the patient on early signs of onset.
Serial neurologic assessments of motor and sensory function at frequent intervals occur and the patient is instructed to notify the team of any symptoms. The team intervenes immediately before the injury becomes permanent. Prompt recognition is reversing or limiting the extent of injury in the majority of patients presenting to Penn; Penn's success was presented at the annual meeting of the Society of Thoracic Surgeons.
The Work Is Not Done
The rewards of seeing patients respond to treatment and recover from a complication previously thought unavoidable, unpredictable, and untreatable is most gratifying. Comparable success is reported from centers implementing similar techniques. Yet the problem is not solved. Some patients do not respond to treatment and some of the interventions have inherent risks. Penn is working to identify the most at-risk patients and to refine procedures and protocols to improve safety.
Article written by: Albert T. Cheung, MD
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