Pediatric Hereditary Angioedema as a Cause of Acute Compartment Syndrome of the Hand and Forearm: A Case Report.

BACKGROUND: Compartment syndrome of the upper extremity is a surgical emergency that, when left untreated, can have dire consequences. Its causes are numerous, one of which is the uncommon entity hereditary angioedema, an autosomal dominant disease resulting in edema in a variety of potential locations, including the extremities. This is only the second time hereditary angioedema has been mentioned in the literature as a cause of compartment syndrome. METHODS: We present a case of hereditary angioedema leading to hand and forearm compartment syndrome in a 13-year-old pediatric patient. Diagnosis of hereditary angioedema was made by our Rheumatology colleagues with physical exam and a thorough history, and confirmed by laboratory studies. RESULTS: Our patient presented with compartment syndrome of the hand and forearm and underwent hand and volar forearm fasciotomies. She was subsequently worked up for hereditary angioedema with laboratory results confirming the diagnosis. She was discharged after a 5-day hospitalization with prophylactic C1-inhibitor therapy. CONCLUSIONS: Hereditary angioedema is a rare but known cause of compartment syndrome of the upper extremity, and must be considered when patients present with compartment syndrome of unknown etiology. This disease can be diagnosed by laboratory studies and symptoms can be controlled with medical therapy.

Preventing Instrumentation Failure in Three-Column Spinal Osteotomy: Biomechanical Analysis of Rod Configuration.

STUDY DESIGN: Biomechanical analysis. OBJECTIVES: To show the role of additional rods and long-term fatigue strength to prevent the instrumentation failure on three-column osteotomies. SUMMARY OF BACKGROUND DATA: Three-column osteotomy such as pedicle subtraction osteotomy (PSO) and vertebral column resections are surgical correction options for fixed spinal deformity. Posterior fixation for the PSO involves pedicle screw-and rod-based instrumentation, with the rods being contoured to accommodate the accentuated lordosis. Pseudarthrosis and instrumentation failure are known complications of PSO. METHODS: Unilateral pedicle screw and rod constructs were mounted in ultra-high-molecular-weight polyethylene blocks using a vertebrectomy model with the rods contoured to simulate posterior fixation of a PSO. Each construct was cycled under a 200 N load at 5 Hz in simulated flexion and extension to rod failure. Three configurations (n = 5) of titanium alloy rods were tested: single rod (control), double rod, and bridging rod. Outcomes were total cycles to failure and location of rod failure. RESULTS: Double-rod and bridging-rod constructs had a significantly higher number of cycles to failure compared with the single-rod construct (p < .05). Single-rod constructs failed at or near the rod bend apex, whereas the majority of double-rod and bridging-rod constructs failed at the screw-rod or rod-connector junction. CONCLUSIONS: Double-rod and bridging-rod constructs are more resistant to fatigue failure compared with single-rod constructs in PSO instrumentation and could be considered to mitigate the risk of instrumentation failure.

Hyperglycemia adversely modulates endothelial nitric oxide synthase during anesthetic preconditioning through tetrahydrobiopterin- and heat shock protein 90-mediated mechanisms.

BACKGROUND: Endothelial nitric oxide synthase activity is regulated by (6R-)5,6,7,8-tetrahydrobiopterin (BH4) and heat shock protein 90. The authors tested the hypothesis that hyperglycemia abolishes anesthetic preconditioning (APC) through BH4- and heat shock protein 90-dependent pathways. METHODS: Myocardial infarct size was measured in rabbits in the absence or presence of APC (30 min of isoflurane), with or without hyperglycemia, and in the presence or absence of the BH4 precursor sepiapterin. Isoflurane-dependent nitric oxide production was measured (ozone chemiluminescence) in human coronary artery endothelial cells cultured in normal (5.5 mm) or high (20 mm) glucose conditions, with or without sepiapterin (10 or 100 microm). RESULTS: APC decreased myocardial infarct size compared with control experiments (26 +/- 6% vs. 46 +/- 3%, respectively; P < 0.05), and this action was blocked by hyperglycemia (43 +/- 4%). Sepiapterin alone had no effect on infarct size (46 +/- 3%) but restored APC during hyperglycemia (21 +/- 3%). The beneficial actions of sepiapterin to restore APC were blocked by the nitric oxide synthase inhibitor N (G)-nitro-L-arginine methyl ester (47 +/- 2%) and the BH4 synthesis inhibitor N-acetylserotonin (46 +/- 3%). Isoflurane increased nitric oxide production to 177 +/- 13% of baseline, and this action was attenuated by high glucose concentrations (125 +/- 6%). Isoflurane increased, whereas high glucose attenuated intracellular BH4/7,8-dihydrobiopterin (BH2) (high performance liquid chromatography), heat shock protein 90-endothelial nitric oxide synthase colocalization (confocal microscopy) and endothelial nitric oxide synthase activation (immunoblotting). Sepiapterin increased BH4/BH2 and dose-dependently restored nitric oxide production during hyperglycemic conditions (149 +/- 12% and 175 +/- 9%; 10 and 100 microm, respectively). CONCLUSION: The results indicate that tetrahydrobiopterin and heat shock protein 90-regulated endothelial nitric oxide synthase activity play a central role in cardioprotection that is favorably modulated by volatile anesthetics and dysregulated by hyperglycemia. Enhancing the production of BH4 may represent a potential therapeutic strategy.