Epidural hematoma associated with dextran infusion.

Key Points

* Epidural hematoma can occur in association with epidural anesthesia.

* Anticoagulant therapy should be used cautiously in patients receiving epidural anesthetics.

* Dextran decreases platelet adhesiveness and increases the development of fibrin clots, which are more vulnerable to lysis.

Case Report

A 79-year-old woman with known peripheral vascular disease and a longstanding history of right lower-extremity claudication presented for right femoral-popliteal bypass grafting. The patient's past medical history was significant for coronary artery disease, hypertension, and asymptomatic chronic lymphocytic leukemia (baseline leukocyte count was increased at 15.3 x [10.sup.9]/L). The patient also had an unspecified hyperlipidemia. An occipital cerebrovascular accident 2 years earlier left the patient legally blind. Past surgical history included fight cataract extraction and placement of a left vertebral artery stent. The patient denied a history of anesthetic complications. The patient had a 35-pack/yr smoking history but had quit smoking 1 year preoperatively. Her medications included atorvastatin (Lipitor; Pfizer, Inc., New York, NY) and 325 mg aspirin daily. The patient used alcohol only occasionally.

Results of a preoperative anesthetic examination were satisfactory, and after a discussion of the risks, options, and anesthesia alternatives, it was agreed to perform a combined general-regional technique. This included a lumbar epidural catheter for intraoperative anesthesia and analgesia (also to be used for postoperative pain control) and general anesthesia with a laryngeal mask airway. A lumbar epidural catheter was placed before induction through the L3-L4 interspace without complication at 7:10 AM. An initial loading dose of bupivacaine 0.25% (12 ml) was administered. This and subsequent bolus doses of 5 ml/h were well tolerated.

General anesthesia was induced with 150 mg propofol intravenously at 7:30 AM, and the laryngeal mask airway was placed without complication. The surgical procedure was uncomplicated. The patient was administered 4,000 U standard heparin intravenously before placement of an arterial cross-clamp at 9:32 AM. No repeat heparin doses were administered in the intraoperative or postoperative period. Protamine was not administered. At the conclusion of the operation (12:42 PM), the patient was delivered to the postanesthesia care unit in satisfactory condition. An epidural infusion of 50 [micro]g/h of fentanyl was started. Pain was adequately controlled with this infusion, and the patient was transferred from the unit at 2:18 PM when all dismissal criteria were met.

The patient was admitted to the intermediate care ward. In an effort to maintain graft patency, a dextran 40 infusion of 30 ml/h was started. The usual practice is to continue dextran infusion for 24 hours after the completion of the operation. This drug and its infusion rate are standard for our vascular surgery service. This infusion was begun shortly after arrival in the intermediate care ward, about 2:30 PM. The patient did well in the early postoperative period. The surgical service evaluated the patient at approximately 7:00 PM and reported that the patient was doing well. Pain was adequately controlled with a fentanyl epidural infusion at 50 [micro]g/h.

At midnight, the patient began to complain of mid- to low back pain. The epidural infusion was increased to 70 [micro]/h on orders of the surgical service, and the patient was repositioned. By early morning (6:00 AM on Day 2), she complained of progressive and localized low back pain. She denied any lower-extremity pain, numbness, or weakness. No neurologic deficits were identified at physical examination. Computed tomography of the lumbar spine was ordered to rule out epidural hematoma. The anesthesia pain service was also asked to evaluate the patient. The anesthesia pain service routinely follows only patients receiving epidural infusions. Because spinal epidural hematoma was suspected, the dextran infusion was stopped at approximately 7:00 AM on Day 2. At the time the dextran 40 infusion was discontinued, it had been running for approximately 16.5 hours. A total of 495 ml dextran 40 solution had been infused intravenously.

Computed tomography did not provide adequate visualization of the upper lumbar and lower thoracic spine. Although computed tomography of the lumbar and lower thoracic spine had been ordered, this order was misinterpreted and only the lumbar spine and the lowest portion of the T12 level were scanned. Although the scan was suggestive of an epidural hematoma, the radiologist suggested that magnetic resonance imaging of the lumbar and thoracic spine be performed to confirm the diagnosis and delineate the extent of the hematoma.

Magnetic resonance imaging of the upper lumbar and lower thoracic spine demonstrated an epidural hematoma extending from T8-T12 with displacement and mild compression of the lower thoracic spinal cord. The greatest mass effect was at the T11-T12 level, which was where the epidural catheter tip was positioned (Figs. 1 and 2).

[FIGURES 1&2 OMITTED]

After neurosurgical evaluation was performed at approximately 9:30 AM on Day 2, the patient was taken to the operating suite for emergency decompressive laminectomy and evacuation of the epidural hematoma. At arrival at the operating room, she continued to deny lower extremity symptoms, and there were no neurologic deficits. The operation was begun at approximately 11:00 AM on Day 2. Results of preoperative coagulation tests were normal. None were performed after surgery. There was no clinical evidence of a coagulation disorder postoperatively. The patient had a complete recovery from both the vascular procedure and the decompressive laminectomy.

Epidural anesthesia is commonly used in patients undergoing revascularization procedures of the lower extremities and other surgical procedures. Complications of epidural anesthesia are uncommon and are usually related to dural puncture or side effects of the medications being infused. Epidural hematoma is a rare complication of epidural anesthesia. Patients who undergo anticoagulation therapy generally are not considered candidates for epidural anesthesia. Management of patients in whom anticoagulation is planned is more problematic. It is generally considered safe to administer low-dose subcutaneous or intravenous standard (unfractionated) heparin as long as the needle puncture is performed 1 hour before heparin administration and the epidural catheter is removed when bleeding study results are normal. (1) Dextran is a colloid that was commonly used for volume resuscitation. This use is now uncommon because of adverse reactions associated with infusion of large volumes. These adverse reactions include anaphylactoid reactions and antithrombotic actions. Some vascular surgeons use the antithrombotic actions of dextran to promote graft patency by using low-dose infusions after peripheral revascularization. (2) We believe that this is the first description of epidural hematoma in association with dextran infusion.

Discussion

Epidural anesthesia is used frequently during vascular procedures. Christopherson et al (3) showed that epidural anesthesia dramatically improved graft patency in patients undergoing peripheral revascularization. The mechanism by which neuraxial anesthesia improves graft patency is not certain but, in part, may be due to vasodilatation and a decrease in plasminogen activator inhibitor-1. To prevent thrombus formation, vascular surgeons frequently administer standard (unfractionated) heparin intraoperatively before cross-clamping major arteries. Rao and El-Etr (4) studied 4,000 patients who had indwelling epidural catheters and systemic heparinization during vascular operations and found no increased risk of epidural hematoma in that population, ha that study, standard heparin was administered at least 60 minutes after epidural catheter placement (as in our patient) and the catheters were removed after results of coagulation studies returned to normal.

Low-dose subcutaneous standard heparin is used widely for thromboprophylaxis in high-risk surgical patients. Schwander and Bachmann (5) reviewed reports of more than 5,000 patients in the literature and found no epidural hematoma reported. During subcutaneous prophylaxis with standard heparin, there is no contraindication to neuraxial techniques. (1) It is recommended that beparin be administered 1 hour after needle placement. Performing neuraxial techniques when heparin has been administered intraoperatively is acceptable, although the use of other medications such as nonsteroidal antiinflammatory drugs may increase the risk of bleeding complications. There are no reports in the literature that address this point. (6)

Although not used in our patient, low-molecular-weight heparin (LMWH) (Lovenox; Aventis Pharmaceuticals, Inc., Bridgewater, NJ) is also used for thromboprophylaxis and merits special notice. More than 40 cases of epidural hematoma in association with neuraxial anesthesia and LMWH have been reported in the past 5 years in the United States. (7,8) This high incidence may be due to the higher level of anticoagulation associated with LMWH. The Food and Drug Administration has issued a public health advisory regarding the use of LMWH and neuraxial injections.

Antiplatelet drugs, by themselves, seem to have no added significant risk for the development of spinal hematomas. There is no literature regarding the combination of antiplatelet drugs and other anticoagulants. There are no concerns about the timing of epidural anesthesia and the dosing of nonsteroidal anti-inflammatory drugs. (6,9)

Dextran inhibits thrombus formation by two mechanisms. (2) First, dextran enhances the conversion of fibrinogen to fibrin. Fibrin is structurally and functionally inferior to fibrinogen and, thus, fibrin clots are more vulnerable to lysis. This effect occurs within 2 to 8 hours of the infusion of dextran and is dependent on the dose and molecular size of the dextran used. Second, dextran reduces the level of factor VIII activator, which decreases platelet adhesiveness and aggregation. The effects of other anticoagulants, antiplatelet medications, and fibrinolytics on development of epidural hematoma are unknown. (8)

Epidural analgesia is a common anesthetic technique. When deciding to use epidural analgesia, the anesthesiologist must consider the risks and benefits. Complications associated with epidural analgesia are infrequent, but some may be devastating (eg, epidural hematoma, epidural abscess, nerve injury). The incidence of epidural hematoma after epidural anesthesia is unknown; however, it is estimated to be 1 in 150,000 cases. (10)

Preexisting bleeding diathesis and ongoing anticoagulation therapy seem to be the leading risk lectors for development of epidural hematomas. Epidural placement technique, difficult placement, and blood encountered during placement have not been shown to increase the risk of epidural hematoma. (11) Epidural hematomas that develop after placement of an epidural catheter usually present with a sudden onset (within a few hours) of symptoms. The presenting symptom is usually back or leg pain. Often, back pain is the predominant symptom. Other signs and symptoms, usually developing later, include sensory or motor deficits in the lower extremities. These signs of spinal cord or cauda equina compression suggest neural ischemia.

Epidural hematoma is an uncommon complication of neuraxial anesthesia, but it may lead to the devastating consequence of paralysis. The cause of the epidural hematoma in our case is unclear. Neither the heparin nor the aspirin in the doses used has been associated with an increased incidence of epidural hematoma. This suggests that the postoperative dextran infusion was an important, if not the primary, causative factor in this case.

For patients in whom signs or symptoms of epidural hematoma develop, emergency neuraxial imaging is warranted. Surgical intervention may be indicated. The effects of local anesthetics may mask pain and sensory and motor deficits. Practitioners should maintain a high level of suspicion and vigilance when evaluating patients with indwelling epidural catheters. Although our patient did not have neurologic deficits at the time of the spinal operation, she had intense back pain related to the spinal epidural hematoma. This pain and the uncertain outcome, in particular, the possibility of neurologic deficits developing, led the neurosurgical consultant to feel that operation was in the patient's best interest.

The volume of the epidural hematoma could not be estimated accurately. Magnetic resonance imaging showed it to be approximately 1.2 cm in diameter at its widest point. The epidural hematoma extended for approximately 5 cm in the thoracic epidural space. The epidural hematoma, in fact, was fusiform, exerting its greatest mass effect at T11-T12, where it occupied approximately half of the central canal area, displacing the spinal cord ventrally and to the left.

In a study of patients undergoing magnetic resonance imaging after epidural blood patch procedure to manage postdural puncture headache, Vakharia et a112 demonstrated that a 20-ml epidural blood patch would produce a hematoma in the posterior epidural space. The mean spread of a 20-ml blood patch was 4.6 intravertebral spaces. There was anterior layering of blood in one patient. None of these patients had radicular symptoms during or after the blood patch procedure. In addition, the report did not note the development of spinal stenosis as a result of the blood patch. It is likely that the patient's preexisting degenerative disk disease and the hematoma at the T11-TI2 level were responsible for the symptoms, rather than the volume of the spinal hematoma per se.

The patient described had a peripheral revascularization procedure. She was taking aspirin preoperatively and was administered 4,000 U heparin sulfate intraoperatively and a dextran 40 infusion postoperatively. She received one dose of standard heparin 15 hours before the onset of symptoms from the epidural hematoma. The symptoms occurred when the anticoagulant effect of heparin would be expected to have dissipated. (13) This suggests that heparin was unlikely to have played a role in the development of the epidural hematoma. There is no information in the literature regarding any potential interaction between aspirin and dextran.

Conclusion

We report a case of epidural hematoma in association with a dextran infusion and epidural anesthesia and analgesia. We think that it is unlikely that the single heparin dose administered was a significant factor in the development of the epidural hematoma. Individually, the anticoagulants that the patient received have not been shown to increase the risk of epidural hematoma. Patients receiving epidural anesthesia and analgesia and dextran infusions should be monitored carefully for possible complications.

References

(1.) Liu SS, Mulroy MF. Neuraxial anesthesia and analgesia in the presence of standard heparin. Reg Anesth Pain Med 1998;23(Suppl 2):157-163.

(2.) Micromedex Healthcare Series. Dextran: Adverse effects [Computer file]. Englewood, CO, Micromedex, Inc., 2001.

(3.) Christopherson R, Beattie C, Frank SM, Norris EJ, Meinert CL, Gottlieb SO, et al. Perioperative morbidity in patients randomized to epidural or general anesthesia for lower extremity vascular surgery: Perioperative Ischemia Randomized Anesthesia Trial Study Group. Anesthesiology 1993;79:422-434.

(4.) Rao TL, El-Etr AA. Anticoagulation following placement of epidural and subarachnoid catheters: An evaluation of neurologic sequelae. Anesthesiology 1981;55:618-620.

(5.) Schwander D, Baehmann F. Heparin and spinal or epidural anesthesia: Decision analysis [in French]. Ann Fr Anesth Reanim 1991;10:284 296.

(6.) Urmey WF, Rowlingson J. Do antiplatelet agents contribute to the development of perioperative spinal hematoma? Reg Anesth Pain Med 1998;23(Suppl 2):146 151.

(7.) Horlocker TT, Wedel DJ. Neuraxial block and low-molecular-weight heparin: Balancing perioperative analgesia and thromboprophylaxis. Reg Anesth Pain Med 1998;23(Suppl 2):164 177.

(8.) American Society of Regional Anesthesia. Neuraxial anesthesia and anticoagulation consensus statements. Presented at the American Society of Regional Anesthesia Consensus Conference, May 2-3, 1998, Chicago, IL.

(9.) Horlocker TT, Wedel DJ, Offord KP. Does preoperative antiplatelet therapy increase the risk of hemorrhagic complications associated with regional anesthesia? Anesth Analg 1990;70:631-634.

(10.) Horlocker TT, Wedel DJ. Neurologic complications of spinal and epidural anesthesia. Reg Anesth Pain Med 2000;25:83-98.

(11.) Vandermeulen EP, Van Aken H, Vermylen J. Anticoagulants and spinal-epidural anesthesia. Anesth Analg 1994;79:1165-1177.

(12.) Vakharia SB, Thomas PS, Rosenbaum AE, Wasenko JJ, Fellows DG. Magnetic resonance imaging of cerebrospinal fluid leak and tamponade effect of blood patch in postdural puncture headache. Anesth Analg 1997;84:585-590.

(13.) Hirsh J, Raschke R, Warkentin TE, Dalen JE, Deykin D, Poller L. Heparin: Mechanism of action, pharmacokinetics, dosing considerations, monitoring, efficacy, and safety. Chest 1995;108(Suppl):258S-75S.

From the Department of Anesthesiology, Mayo Clinic, Scottsdale, AZ.

Reprint requests to Jesse J. Muir, MD, Department of Anesthesiology, Mayo Clinic, 13400 E. Shea Boulevard, Scottsdale, AZ 85259.

Accepted August 2, 2002.