Development of adaptive pneumatic tourniquet systems based on minimal inflation pressure for upper limb surgeries.

BACKGROUND: Pneumatic tourniquets are medical devices that occlude blood flow to distal part of extremities and are commonly used in upper limb surgeries to provide a dry, clean and bloodless field. To decrease pressure-related injuries and potential risk of complications subjected to the high inflation pressure of pneumatic tourniquet, minimal inflation pressures are recommended. METHODS: A new occlusion pressure mathematical model for the upper limb was established based on the correlation analysis between several possible influencing parameters and the minimal pneumatic tourniquet pressure at which the peripheral pulse disappeared was recorded using a digital plethysmograph. A prototype of an adaptive pneumatic tourniquet which automatically varies the pressure in the tourniquet cuff according to the above prediction model was developed for the upper limb which used the lowest possible inflation pressure to achieve occlusion. The prototype comprises a blood pressure monitoring module, an inflatable tourniquet cuff, and a pressure relief mechanism to maintain an optimal cuff inflation pressure. Simulation experiments were conducted to verify the function and stability of the designed adaptive pneumatic tourniquet and clinical experiments using volunteers were undertaken to evaluate the performance of the prototype design in achieving adequate haemostasis in the upper limb. RESULTS: Results demonstrated that the mean arterial occlusion pressure was 152.3 ± 16.7 mmHg, obviously below the 250 to 300 mmHg previously recommended (J Bone Joint Surg Br 68:625-628, 1986 and Arthroscopy 11:307-311, 1995). CONCLUSIONS: In conclusion, this adaptive method and apparatus which can provide minimal inflation pressure may be a clinically practical alternative for upper limb surgery performed with pneumatic tourniquets.

Inhibitory effects of ultrasonic and rosmarinic acid on lipid oxidation and lipoxygenase in large yellow croaker during cold storage.

Lipid oxidation will lead to the deterioration of flavor, color and texture of aquatic products with high fatty acid content. The mechanism of ultrasound (US) combined with rosmarinic acid (RA) on lipid oxidation and endogenous enzyme activities of large yellow croaker during cold-storage (4 ℃) was investigated. The result showed that the US and RA have synergistic effects in delaying lipid oxidation and inhibiting endogenous lipase and lipoxygenase (LOX) activities related to oxidation. The inhibition of LOX activity by RA was dose-dependent, and US showed a negative effect on the inhibition of enzyme activity in the presence of low concentration RA. Moreover, RA changes the enzyme structure through static fluorescence quenching and interaction with enzyme molecules. Hydrogen bonding and hydrophobic interaction are the main interaction forces between RA and LOX. This study could provide basic mechanism of US treatment cooperating with polyphenols to inhibit lipid oxidation during food preservation.

Evaluation of emergency tourniquets for prehospital use in China.

OBJECTIVE: Massive hemorrhage is life-threatening during armed conflicts. Tourniquets are important medical devices used to reduce severe bleeding in trauma. The aim of this study was to empirically evaluate the current tourniquets used in China and provide information to emergency nurses in selecting the appropriate tourniquet. METHODS: Five tourniquets were self-applied by 20 healthy participants. The blood flow distal to the tourniquet site was assessed using vascular Doppler ultrasound. Application time, pain, numbness, and other parameters were evaluated. RESULTS: The bladder tourniquet and windlass tourniquet effectively occluded arterial blood flow with success rates higher than 75% in both the upper and lower extremities. The Cargo-strap was the fastest to apply, taking (7.22+/-2.30) s for the upper extremity and (6.48+/-2.40) s for the lower extremity. The rubber tube was the most painful, and the improvised tourniquet was the least efficient. The success rates were higher in the lower extremity than in the upper extremity (P less than 0.05, X(2) equal to 5.714). CONCLUSIONS: The bladder tourniquet and the windlass tourniquet are efficient tourniquets, although the windlass is superior with respect to portability and pain. The Cargo-strap and rubber tourniquets have several disadvantages that reduce their suitability for field use. The improvised tourniquet is not recommended because of low efficiency and severe pain during implementation.

Morphological evolution and ordered quantum structure formation in heteroepitaxial core--shell nanowires.

We have performed three-dimensional dynamic simulations to study strain-driven morphological evolution and the formation of quantum structures on heteroepitaxial core--shell nanowire surfaces. Our simulations show that depending on geometric and material parameters, such as the radius of the wire, the thickness of the shell, and the mismatch strain, various surface morphologies including smooth core--shell nanowire surfaces, nanoring arrays, nanowire arrays, and ordered quantum dot arrays can be obtained by controlling initial surface configurations through prepatterning. It is also shown that these quantum structures may be trapped in a metastable state and may undergo a series of metastable state transitions during subsequent dynamic evolution. Our results identify possible pathways for fabrication of ordered quantum structures on the epitaxial core--shell nanowire surfaces and provide guidelines for achieving smooth core--shell structures.