Aortic Perforation During Lumbar Laminectomy

Lumbar laminectomy is a common and usually routine operation, but it can occasionally result in sudden, life-threatening complications. Such events usually require rapid therapy, so it is essential that anesthesiologists be aware of these potential complications, as well as their manifestations and treatment. We report the occurrence of aortic perforation, an uncommon but potentially fatal complication of lumbar laminectomy. Case Report A 42-yr-old, healthy woman (56 kg, 160 cm) was admitted for L5-S1 laminectomy. Her medical history was significant only for an allergy to penicillin and nicotine abuse (hemoglobin 15.1 g/dL, ASA physical status II). Preparation for surgery was routine, and cross-matching of blood was not performed. After the application of monitors (electrocardiogram, pulse oximeter, capnograph, and noninvasive blood pressure device) and an IV injection of dehydrobenzperidol (1.25 mg), anesthesia was induced with thiopental 7 mg/kg, fentanyl 7 [micro sign]g/kg, and rocuronium 0.8 mg/kg. Anesthesia was maintained with isoflurane (0.3%-0.6%) administered in 30% oxygen and 70% N2 O with a fresh gas flow of 0.5 L/min. After turning the patient to the kneeling position, surgery commenced uneventfully 20 min after induction. Sudden changes were noted in end-tidal CO2 (from 35 to 28 mmHg), blood pressure (from 110/60 to 80/50 mm Hg), and heart rate (from 59 to 100 bpm) 120 min after incision. While the neurosurgeons investigated possible operative reasons for these changes, 500 mL of 6% hydroxyethyl starch and 1000 mL of lactated Ringer's solution were infused. IV bolus doses of norepinephrine (10 [micro sign]g each) were administered to support blood pressure. Despite this therapy, systolic blood pressure continued to decline to 50 mm Hg, and heart rate increased to 135 bpm. Type 0, Rh negative red blood cells were ordered, and cross-matched red blood cells were requested. The patient was turned to the supine position. While the vascular surgeons were informed, a right internal jugular venous catheter (12-French) was placed, and volume resuscitation was continued (4500 mL of 6% hydroxyethyl starch, 3000 mL of 3% gelatin) [13,14], accompanied by a continuous norepinephrine infusion (1 [micro sign]g [center dot] kg-1 [center dot] min-1). Emergent laparotomy was performed; 5.5 L of blood was found in the abdominal cavity. Bleeding resulted from perforation of the abdominal aorta and the right common iliac vein and was controlled by manual aortic compression. While these injuries were being repaired, transfusion of 4,800 mL of packed red blood cells and 3,400 mL of fresh-frozen plasma was managed with a rapid infusion system. In addition, 14,000 mL of blood was processed using a cell-saver salvage device. The lowest measured hemoglobin concentration was 2.2 g/dL. At transport to the intensive care unit, the hemoglobin concentration had been restored to 10.9 g/dL. The patient left the hospital 14 days later after an uneventful recovery. Discussion This case report describes acute perforation of the aorta and right common iliac vein during L5-S1 lumbar laminectomy, diagnosed intraoperatively by an end-tidal CO2 decrease, followed by a blood pressure decrease and an increase in heart rate. The patient fully recovered after repair of the vascular perforation. Major vascular injuries during lumbar laminectomy (first reported in 1945) [1] are uncommon (0.017%-0.142%) [3,4]. As a result, when such an event does occur, the cause may not be recognized, leading to a high mortality (78%-100%) in otherwise healthy patients [4]. Vascular injury most often results from damage caused by instruments, such as a pituitary rongeur (Figure 1) [5]. The aorta, common iliac arteries, and/or iliac vein can be involved, depending on the level at which the laminectomy is performed (Figure 2) [5]. In addition to laceration of the retroperitoneal vessels [2-5], perforation of the bladder [6] or small intestine [7], laceration of the uterus, and formation of a false aneurysm [8] have been reported.Figure 1: Mechanism of vascular injury during lumbar disk surgery. With penetration anterior to the disk space, injury to retroperitoneal or intraabdominal structures is likely, particularly if the surgeon is unaware of the exact location of the instrument. Injury to the ureter, sympathetic chain, small intestine, bladder, and even appendix has been reported. Because of the anatomical proximity of the major vessels immediately anterior to the vertebral bodies, vascular injuries are more frequent. This Figure usedwith permission of the American Medical Association (copyright 1979) and Dr. D. C. Brewster [5].Figure 2: Location of vascular injuries during laminectomy. The exact location of vessel injury depends on several factors, including disk space operated on, individual anatomy, and angle of the exploring instrument. The majority of the reported injuries have followed operation on the L4-5 disk space and have involved injury to the common iliac vessels. Location of vascular injuries in six previously reported cases; triangles indicate arterial injuries, ovals indicate arteriovenous fistulae. This Figure usedwith permission of the American Medical Association (copyright 1979) and Dr. D. C. Brewster [5].In most of the reported cases in the prone position, the early signs of blood loss were hypotension, hypovolemia [5], and a decrease in oxygen saturation [9]. In our case, the first sign was a sudden decrease in end-tidal CO2 probably occurring because of decreased blood flow to the lungs. Alternative explanations for sudden changes in respiratory hemodynamic variables should be considered. Venous air embolism [10], allergic reactions [11], and acute mitral valve regurgitation can exhibit similar manifestations. However, erroneous or delayed diagnosis of vascular injuries can lead to a disastrous outcome [9], whereas immediate surgical treatment can be life-saving [2]. Therefore, if major vascular injury is suspected, the primary surgery procedure should be interrupted, and the patient should be turned and prepared rapidly for laparotomy. A rapid infusion of crystalloids or colloids should be used [12-14] until packed red blood cells are available for infusion. In addition to routine perioperative monitoring, emergency sonography facilitates differentiation between suspected aortic perforation [15,16] and other causes of acute clinical deterioration [e.g., mitral valve regurgitation [16], suspected uterine [17], bowel [18], or bladder perforation [19]]. However, surgical treatment can be life-saving and should not be delayed by diagnostic procedures. Continued awareness of the possible occurrence of such injuries and familiarity with their variable manifestations should enhance early diagnosis, prompt operative repair, and improved patient survival after these disastrous events.