Background: Cardiovascular complications are common in patients with obstructive sleep apnea (OSA). Blood rheology is a major determent of coagulation and an established risk factor for cardiovascular events. Since nocturnal hypoxemia could influence parameters of blood rheology, we hypothesized that OSA alters blood rheology independent of other cardiovascular risk factors. Methods: One hundred and ten consecutive patients admitted to the sleep laboratory were included. The association of plasma fibrinogen and viscosity (as parameters of blood rheology) with OSA was evaluated. Results: One hundred and ten patients aged 61.4 ± 10.1 years (body mass index 28.4 ± 4.1 kg/m²) were included. OSA was confirmed in 63 patients (57.2%) with an apnea-hypopnea index (AHI) of 28.7 ± 14.9 events/hour. Patients with OSA showed higher levels of plasma viscosity (1.36 ± 0.09 vs. 1.31 ± 0.08 mPas, p = 0.005). Nevertheless, hypertensive apneics have even higher levels of plasma viscosity than nonapneics (1.38 ± 0.091 vs. 1.32 ± 0.028 mPas, p = 0.018). Similar results were found in patients with coronary artery disease, where OSA was associated with elevated plasma viscosity (1.36 ± 0.076 vs. 1.31 ± 0.081 mPas, p = 0.007). Plasma fibrinogen was correlated with nocturnal minimal oxygen saturation (r = –0275, p = 0.0036) and AHI (r = 0.297, p = 0.001). OSA was associated with higher plasma fibrinogen (353 ± 83 vs. 317 ± 62 mg/dl, p = 0.015). These differences persist with control for cardiovascular risk factors. Conclusions: Patients with OSA have elevated morning fibrinogen levels and a higher plasma viscosity, which correlate positively with indices of sleep apnea severity. These changes in blood rheology are independent of cardiovascular risk factors, and therefore, might be specific mechanisms of OSA. This supports the pathophysiological concept that sleep apnea is a cardiovascular risk factor.

Introduction: The aim of this study was to assess alterations in median nerve (MN) biomechanics within the carpal tunnel resulting from ultrasound-guided hydrodissection in a cadaveric model. Methods: Twelve fresh frozen human cadaver hands were used. MN gliding resistance was measured at baseline and posthydrodissection, by pulling the nerve proximally and then returning it to the origin. Six specimens were treated with hydrodissection, and 6 were used as controls. Results: In the hydrodissection group there was a significant reduction in mean peak gliding resistance of 92.9 6 34.8 mN between baseline and immediately posthydrodissection (21.4% 6 10.5%; P 5 0.001). No significant reduction between baseline and the second cycle occurred in the control group: 9.6 6 29.8 mN (0.4% 6 5.3%; P 5 0.467). Discussion: Hydrodissection can decrease the gliding resistance of the MN within the carpal tunnel, at least in wrists unaffected by carpal tunnel syndrome. A clinical trial of hydrodissection seems justified.

Background The aim of this study was to compare the effectiveness of ultrasound-guided injections to blind injections in the treatment of carpal tunnel syndrome (CTS) in a large community-based cohort. Methods This study evaluated residents of Olmsted County, MN, USA, treated with a corticosteroid injection for CTS between 2001 and 2010. The proportion of patients receiving retreatment and the duration of retreatment-free survival between blind and ultrasound-guided injections were compared. Propensity score matching was used to control for confounding by indication. Results In the matched dataset consisting of 234 (out of 600) hands treated with a blind injection and 87 (out of 89) ultrasound-guided injection cases, ultrasound guidance was associated with a reduced hazard of retreatment (hazard ratio, 0.59; 95% confidence interval [CI], 0.37 - 0.93). In addition, ultrasound guidance was associated with 55% reduced odds of retreatment within one year compared to blind injections (adjusted odds ratio, 0.45; 95% CI, 0.24 - 0.83). Conclusion This study indicates that ultrasound-guided injections are more effective in comparison to blind injections in the treatment of CTS.