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.

Dilution of rocuronium to 0.5 mg/mL with 0.9% NaCl eliminates the pain during intravenous injection in awake patients.

In a randomized, double-blinded, controlled study, we evaluated the effect of diluting rocuronium 10 mg/mL to 1 or 0.5 mg/mL with 0.9% NaCl on the pain associated with IV administration of rocuronium with small doses given before succinylcholine or nondepolarizing agent administration. One hundred fifty patients undergoing surgical procedures that required general anesthesia were randomized into three groups. Group 1 received rocuronium 10 mg/mL. Groups 2 and 3 received 1 and 0.5 mg/mL of rocuronium, respectively. Patient demographics, pain scores, osmolality, and the pH of the solutions were recorded. Group 1 had the most intense and frequent pain response. Eighty percent of patients in this group reported pain on injection. In Group 2, the incidence and intensity of pain were significantly less when compared with those of Group 1. In this group, 38% of patients reported pain during injection. In Group 3, none of the patients experienced pain on injection. The pH values and osmolalities of study solutions were not significantly different among groups. In conclusion, in awake patients, dilution of rocuronium 10 mg/mL at small doses given before succinylcholine or nondepolarizing agent administration of 0.06 mg/kg to 0.5 mg/mL with 0.9% NaCl is a simple and cost-effective strategy for preventing pain during IV rocuronium injection.

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.