Medial transposition of the radial nerve for anterolateral plate fixation of the humerus: cadaveric study.

In the operative treatment of humeral shaft fractures the radial nerve may be injured during the reduction of fracture fragments or the application of plate and screws. Also, secondary surgical explorations due to delayed or non-union carry a high risk of radial nerve injury because of the scarring of the neighboring tissue and proximity of the nerve to the implants. Consequently, the need for the transposition of the radial nerve to a safer position arises. A total of 22 (11 right, 11 left) cadaveric upper extremities were studied to evaluate the medial transposition of the radial nerve during the open reduction and anterolateral plate fixation of humeral fractures. The radial nerve was transposed medially in a distal plate fixated humeral fracture model. Distance measurements of the radial nerve and the division points of its branches were carried out in the transposed position and in the original course of the nerve. There was no statistically significant difference between the original course and medially transposed measurements. The distances from the reference point to the division points of other branches (posterior antebrachial cutaneous nerve, motor branch to brachioradialis, most distal motor branch to triceps) were not altered. The mean length of the radial nerve was 185.2 +/- 14.3 mm in its original course and 183.7 +/- 13.8 mm in the medially transposed course. In conclusion, the present study shows that medial transposition of the radial nerve through the fracture line does not increase the nerve's length and may be utilized in cases in which anterolateral plate fixation is indicated.

A new method for estimating arterial occlusion pressure in optimizing pneumatic tourniquet inflation pressure.

To reduce pressure-related injuries resulting from pneumatic tourniquet use, the lowest possible inflation pressure is recommended. Arterial occlusion pressure (AOP) is a measure of the cuff pressure required to maintain a bloodless surgical field. However, its determination method is time consuming, requires operator skill, and is therefore seldom used in current practice. An AOP estimation can be made by knowing the pressure transmitted to the underlying soft tissues. We measured upper and lower extremity tissue pressures under the tourniquet cuff at 100, 200, and 300 mm Hg of tourniquet inflation pressures in 30 anesthetized living adult patients. All patients received general anesthesia with neuromuscular relaxation. A Stryker intra-compartmental pressure monitor was used to measure tissue pressures under the tourniquet cuff. In all patients, the soft tissue pressures were consistently lower than the applied tourniquet inflation pressures. Our results revealed tissue padding coefficients for extremities 20 to 75 cm in circumferences. An estimation method of AOP was developed [AOP = (systolic blood pressure + 10)/Tissue padding coefficient]. The new AOP estimation method may be a simple, rapid, and clinically practical alternative to the AOP determination method.

Controlled hypotension and minimal inflation pressure: a new approach for pneumatic tourniquet application in upper limb surgery.

UNLABELLED: Minimal inflation pressures are recommended for limb surgery to eliminate complications attributable to high inflation pressures with the pneumatic tourniquets. We applied controlled hypotension and a minimal inflation pressure (CHAMIP) technique to provide a bloodless surgical field. Thirty-six patients scheduled for upper extremity surgery were randomized equally to receive either normotensive anesthesia and conventional inflation pressures or controlled hypotension (systolic arterial blood pressure of 80-100 mm Hg and mean arterial blood pressure >60 mm Hg) and minimum inflation pressures. Anesthesia was induced with propofol IV bolus and remifentanil IV continuous infusion and maintained with propofol and remifentanil IV continuous infusion. To determine the minimal inflation pressure, the digital plethysmograph was applied to the second finger at the side of the operation and the tourniquet was inflated slowly until the arterial pulsations disappeared on the oscilloscope. A bloodless surgical field was obtained in almost all patients, even though systolic arterial blood pressures (100-138 mm Hg versus 80-100 mm Hg) and applied tourniquet inflation pressures (270 mm Hg versus 110-140 mm Hg) were significantly lower in the hypotensive group. No complications associated with controlled hypotension were encountered. In conclusion, CHAMIP may be a safe and reliable method for upper extremity surgery performed with pneumatic tourniquets. IMPLICATIONS: Pneumatic tourniquets are associated with adverse effects resulting from high inflation pressures. Therefore, minimal inflation pressures are recommended in extremity surgery. To reach real minimal inflation pressure the patient's blood pressure must be reduced. We used controlled hypotension with remifentanil and propofol to reach minimal inflation pressures.