Prolonged Spine Surgery Research Articles

Rhabdomyolysis is a Potential Complication of Total Hip Arthroplasty in the Morbidly Obese

Rhabdomyolysis (RML) can complicate prolonged surgery and may lead to renal failure and death. Obese patients are at high risk for this complication. This complication has been recently described in bariatric surgery and prolonged spine surgery, but it is not well recognized in patients undergoing THA. We present an obese patient (BMI = 50) who developed RML and acute kidney injury after a total hip arthroplasty.

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Prolonged Propofol Anesthesia Is Not Associated with an Increase in Blood Lactate

Lactic acidosis is considered an early sign of propofol infusion syndrome. In this study, we investigated the changes in lactate and pH with propofol versus volatile anesthesia (VA) of long duration. Demographic and intraoperative data were recorded retrospectively from the anesthesia records of patients who underwent elective spine surgery longer than 8 h. Propofol patients were matched 1:2 to VA patients, based on anesthesia time (AT) (+/-30 min) and blood loss (BL) (+/-500 mL). Of 246 patients identified, 50 received propofol (AT = 10 +/- 2 h, BL = 1955 +/- 1409 mL) and were matched to 100 VA cases (AT = 10 +/- 1 h, BL = 1801 +/- 1543 mL), and of those, 40 and 72 patients, respectively, had complete lactate data at baseline and at 8 h after anesthesia and were included in the main analysis. The propofol group received 8.8 +/- 2 mg x kg(-1) x h(-1) of propofol. The VA group age was older than the propofol group (58 +/- 12 vs 51 +/- 15 yr, respectively, P = 0.002), but there was no difference between the groups in gender, ASA grade, intraoperative hemodynamic variables, and use of vasopressors. After 8 h, the VA group had a larger increase in arterial lactate from baseline compared with the propofol group (change from baseline: propofol, 0.48 +/- 0.72 mmol/L; VA, 1.2 +/- 1.2 mmol/L, P = 0.001). During prolonged spine surgery >8 h, VA was associated with higher serum lactate, when compared with propofol infusion. Prospective studies are needed to elucidate the exact mechanisms and clinical implications of this finding.

Bilateral Leg Compartment Syndrome Complicating Prolonged Spine Surgery in the Kneeling Position

A case of bilateral compartment syndrome of the legs complicating prolonged spine surgery in the kneeling-90-90 position. Aggressive treatment of the reperfusion injury prevented severe rhabdomyolysis, acute renal failure, and sepsis, although it could not avoid the permanently disabling muscular necrosis. Close postoperative surveillance facilitate an early diagnosis and expedite appropriate treatment.

Dilated Superior Ophthalmic Veins and Posterior Ischemic Optic Neuropathy After Prolonged Spine Surgery

A 55-year-old man developed bilateral posterior ischemic optic neuropathy after prolonged prone position lumbar laminectomy. Brain MRI performed 19 hours after the procedure revealed markedly dilated superior ophthalmic veins, a finding that had disappeared on a comparable study performed 5 months later. This first report of dilated superior ophthalmic veins present in the immediate postoperative period but not later may be important in suggesting that an increase in orbital venous pressure during surgery contributes to the development of postoperative posterior ischemic optic neuropathy (PION).

The Effect of Kneeling During Spine Surgery on Leg Intramuscular Pressure

Acute compartment syndrome has been an underreported complication during spine surgery with the patient positioned on the so-called 90/90 kneeling frame (with 90 degrees of both hip and knee flexion), presumably because of elevated intramuscular pressures in the dependent leg compartments. The purpose of the present study was to characterize and quantify certain parameters that affect the risk for acute compartment syndrome experimentally and to make objective comparisons with other spine surgery positions. Eight healthy volunteers were positioned in three spine surgery positions: the 90/90 kneeling position, the so-called 45/45 suspended position (with the hips and knees both flexed to 45 degrees with the legs suspended on a sling), and the prone position. Intramuscular pressures were measured in all four left leg compartments with slit catheters. Local blood pressure and applied load beneath the leg were also measured. The 90/90 kneeling position was associated with significantly increased intramuscular pressure in the anterior compartment (30.8 +/- 5.7 mm Hg) in comparison with the prone position (13.5 +/- 1.7 mm Hg) and the 45/45 suspended position (13.8 +/- 1.7 mm Hg). In the 90/90 kneeling position, these values correlated with subject weight (r = 0.72, p = 0.045) and the applied body weight load measured beneath the leg (r = 0.74, p = 0.037). The mean differences between intramuscular pressure and ankle blood pressure were more pronounced as the position of the ankle dropped below the level of the heart in the 45/45 suspended and the 90/90 kneeling positions. The 90/90 kneeling position results in elevated intramuscular pressure in the anterior compartment of the leg. This elevated pressure correlates also with subject weight. The 90/90 kneeling position may predispose patients to the development of an acute compartment syndrome during prolonged spine surgery, with heavier patients being at increased risk. In certain instances, the surgeon may consider using the 45/45 suspended position to minimize this risk.

Unilateral postoperative visual loss due to central retinal artery occlusion following cervical spine surgery in prone position

Postoperative visual loss following spinal surgery is a rare complication. Although a number of intraoperative and postoperative factors have been implicated exact etiology still may remain unclear. We report a case of unilateral postoperative visual loss in a patient who had undergone prolonged spine surgery in a prone position.

Visual Loss after Spinal Surgery

Visual Loss after Spinal Surgery

Excessive Crystalloid Infusion May Contribute to Ischemic Optic Neuropathy

David Geffen School of Medicine at UCLA, Los Angeles, California. plarson@ucla.eduIt is unfortunate that Drs. Lee et al. 1and Warner2feel compelled to conclude that blindness may be an inevitable consequence of prolonged spine surgery in the prone position, and that patients should be warned of that possibility. While perhaps correct, my experience in supervising many hundreds of such cases without this complication leads me to believe that it is preventable. Although briefly considered by Dr. Lee et al. in the Discussion section, sufficient attention was not focused on the large average volume of crystalloid solution (9.7 ± 4.7 l) infused in the 83 patients who developed ischemic optic neuropathy. This volume of infusion is far in excess of what is necessary for maintenance of either blood pressure or urine output. In addition, it has a serious negative impact on the hematocrit, as well as promoting edema of the orbs and optic nerves. Although the etiology of blindness may be multifactorial, as anesthesiologists we must critically assess those aspects of care over which we have control. Limiting crystalloid administration, avoiding severe anemia (hematocrit < 26), and limiting the duration of controlled hypotension, if used, to the dissection period only (not the instrumentation period) are all controllable. I would urge anesthesiologists to limit crystalloid volume in prone spine surgical cases to no more than 40 ml/kg (approximately 3 l in adults) for the entire operative procedure regardless of duration. If additional fluid is deemed necessary, it should be hetastarch (not to exceed 20 ml/kg), albumin, or blood. If necessary, a low-dose dopamine infusion can be used to support circulation and improve urine output. Finally, urine output should not be the benchmark for fluid requirements in these patients. Urine output is commonly diminished while patients are in the prone position for reasons that have not been documented. Diminished urine output in this setting does not lead to renal insufficiency postoperatively.David Geffen School of Medicine at UCLA, Los Angeles, California. plarson@ucla.edu