Vascular structures close to the lumbar spine can be injured during the surgical removal of herniated intervertebral discs. Depending on the extent and location of the trauma, the lacerations of the vessels may result in hemorrhage, formation of false aneurysm, or hemodynamically significant arteriovenous fistula (AVF). The frequent mortality of 40%–50% after these vascular injuries is often related to acute blood loss into the retroperitoneal or intraperitoneal space. We describe an iatrogenic AVF with early diagnosis and management resulting in a successful outcome.
A 28-yr-old healthy woman, with symptoms of low back pain and urinary retention, was scheduled for left-sided microdiscectomy of a herniated L4-5 intervertebral disk. Anesthesia was induced with thiopental and tracheal intubation facilitated with succinylcholine. Anesthesia was maintained with isoflurane, nitrous oxide in oxygen, and vecuronium. The patient was positioned prone, and the procedure was uneventful until removal of the disk, which coincided with a sudden decrease in arterial blood pressure from 110/70 to 70/40 mm Hg. There was no significant bleeding in the operative field and no significant decrease in end-tidal CO2. The surgical field was flooded with normal saline to prevent possible air embolism caused by air entrainment into exposed lumbar veins.
The lungs were ventilated with 100% oxygen, the endotracheal tube was position confirmed, and 3 L of lactated Ringer's solution and 1 mg of phenylephrine (100-μg boluses) were administrated. Her arterial blood pressure stabilized at 120/60 mm Hg. A bleeding lumbar vein was ligated, and the rest of the procedure was uneventful. The trachea was extubated in the operating room, and the patient was transferred to the recovery room. On physical examination, the abdomen was soft and nontender, and the lower extremities were nonedematous, with pulses equally palpable. Because of continuing requirements for volume resuscitation and vasopressor medications, the patient was transferred to the intensive care unit where she received 6 U of packed red blood cells. A right-sided abdominal bruit suggested the possibility of an AVF. Angiography was performed, which revealed a fistula between the right common iliac artery and the inferior vena cava (Fig. 1). An emergency exploratory laparotomy was performed for persistent hemodynamic instability. There was no free blood in the peritoneal cavity. However, a large retroperitoneal hematoma extending from the ligament of Treitz to the pelvis was found. The right common iliac artery had a 50% circumferential tear, and the inferior vena cava had a 2.5-cm defect extending into the proximal left common iliac vein. The injuries were repaired, and the patient had an uneventful postoperative course.
The causes of potentially lethal intraoperative hypotension during lumbar disk surgery include hemorrhagic shock caused by iatrogenic vascular injuries (1–10), venous air embolism (11), and anaphylactic drug reactions. We report a case of iatrogenic AVF presenting with unexplained sudden hypotension.
The incidence of vascular injuries, including AVF, lacerations, and pseudoaneurysms during disk operations, is one to five per 10,000 (4). Risk factors include anterior annulus and longitudinal ligament degeneration, improper positioning of the patient, and repeated operations (4,6,11). The interspace most frequently associated with vascular injury is L4-5, corresponding to the common iliac vessels and the vena cava (2,5,6,11). This was the case in our patient.
Angiography is the “gold standard” for diagnosing iatrogenic vascular injury (3). Clinical features and use of angiography, ultrasonography with color-flow Doppler mapping, or computerized tomography are important for early diagnosis (3,12). Because vascular injuries are associated with frequent mortality (40%–50%), diagnostic tests should not delay surgical treatment in hemodynamically unstable patients (3,8,9,13,14).
In young and healthy patients, hypotension from blood loss may be delayed, and retroperitoneal or intraperitoneal bleeding may not be obvious with the patient in the prone position. Therefore, when there is unexplained intraoperative hypotension and anemia during spinal surgery, iatrogenic vascular injury should be considered. Intraoperative death of a young patient caused by aortic injury during discectomy has been reported; electromechanical dissociation from severe hypovolemia was diagnosed as pulmonary embolism because there was no obvious surgical bleeding (15). Early diagnosis and aggressive management are important. If major vascular injury is suspected, discectomy should be interrupted and emergency laparotomy performed, even in the presence of hemodynamic instability (16). Medical antishock trousers had been successfully applied to stabilize hemodynamics until an emergency laparotomy was performed in a patient with life threatening injury to iliac vessels during lumbar discectomy (17).
In contrast to vascular lacerations, AVF may not present with severe symptoms in the first 24 hours. In a case series, the diagnosis was established after 24 hours in 56 of 66 patients with AVF (4). Hemodynamically significant AVF may be associated with anemia, hypovolemia, lower limb edema, abdominal thrill, back and abdominal pain, high output cardiac failure, rectal bleeding, hematuria, and renal failure caused by increased venous pressures (1–4,6–9). These symptoms usually resolve after surgical correction. Percutaneous endovascular repair is less invasive, involves less blood loss, and may be equally successful (18,19). In repairing complicated AVF, cardiopulmonary bypass may be required to enable control and safety (20).
In conclusion, we describe a case of traumatic AVF in a young healthy patient undergoing lumbar disk surgery. Anesthesiologists should be aware of the potential for vascular injuries during lumbar discectomy and be prepared to intervene.
We sincerely thank Mehernoor Watcha, MD, Associate Professor in Anesthesia and Pediatrics, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, for his critical review and suggestions.
1. Brewster DC, Cambria RP, Moncure AC, et al. Aortocaval and iliac arteriovenous fistulas: recognition and treatment. J Vasc Surg 1991;13:253–65.
2. Goodkin R, Laska LL. Vascular and visceral injuries associated with lumbar disc surgery: medicolegal implications. Surg Neurol 1998;49:358–72.
3. Szolar DH, Preidler KW, Steiner H, et al. Vascular complications in lumbar disk surgery: report of four cases. Neuroradiology 1996;38:521–5.
4. Papadoulas S, Konstantinou D, Kourea HP, et al. Vascular injury complicating lumbar disc surgery: a systematic review. Eur J Vasc Endovasc Surg 2002;24:189–95.
5. Quigley TM, Stoney RJ. Arteriovenous fistulas following lumbar laminectomy: the anatomy defined. J Vasc Surg 1985;2:828–33.
6. Jarstfer BS, Rich NM. The challenge of arteriovenous fistula formation following disk surgery: a collective review. J Trauma 1976;16:726–33.
7. May AR, Brewster DC, Darling RC, Browse NL. Arteriovenous fistula following lumbar disc surgery. Br J Surg 1981;68:41–3.
8. Brewster DC, May AR, Darling RC, et al. Variable manifestations of vascular injury during lumbar disk surgery. Arch Surg 1979;114:1026–30.
9. Epstein FH, Post RS, McDowell M. The effect of an arteriovenous fistula on renal hemodynamics and electrolyte excretion. J Clin Invest 1953;32:233–41.
10. Serrano Hernando FJ, Paredero VM, Solis JV, et al. Iliac arteriovenous fistula as a complication of lumbar disc surgery: report of two cases and review of literature. J Cardiovasc Surg (Torino) 1986;27:180–4.
11. Palmon SC, Moore LE, Lundberg J, Toung T. Venous air embolism: a review. J Clin Anesth 1997;9:251–7.
12. Chen IC, Lin FC, Chern MS, et al. Diagnosis of postlaminectomy arteriovenous fistula using color Doppler flow mapping. Am Heart J 1991;121:217–9.
13. Franzini M, Altana P, Annessi V, Lodini V. Iatrogenic vascular injuries following lumbar disc surgery: case report and review of the literature. J Cardiovasc Surg (Torino) 1987;28:727–30.
14. Fruhwirth J, Koch G, Amann W, et al. Vascular complications of lumbar disc surgery. Acta Neurochir (Wien) 1996;138:912–6.
15. Ewah B, Calder I. Intraoperative death during lumbar discectomy. Br J Anaesth 1991;66:721–3.
16. Honemann CW, Brodner G, Van Aken H, et al. Aortic perforation during lumbar laminectomy. Anesth Analg 1998;86:493–5.
17. Hanouz J, Bessodes A, Samba D, et al. Delayed diagnosis of vascular injuries during lumbar discectomy. J Clin Anesth 2000;12:64–6.
18. McCarter DH, Johnstone RD, McInnes GC, et al. Iliac arteriovenous fistula following lumbar disc surgery treated by percutaneous endoluminal stent grafting. Br J Surg 1996;83:796–7.
19. Burger T, Meyer F, Tautenhahn J, et al. Percutaneous treatment of rare iatrogenic arteriovenous fistulas of the lower limbs. Int Surg 1998;83:198–201.
20. Fletcher JP, Klineberg PL, Hawker FH, et al. Arteriovenous fistula following lumbar disc surgery: the use of total cardiopulmonary bypass during repair. Aust N Z J Surg 1986;56:631–3.