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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.

SummaryWe investigated whether insertion of the disposable Soft Seal laryngeal mask airway (SSLM) was successful without intra-oral digital manipulation. One hundred patients undergoing anaesthesia using the SSLM were randomly assigned into two groups. Insertion was performed by either a direct or a rotational technique, both without intra-oral digital manipulation. The primary outcome measure was successful insertion at first attempt. Other outcomes included insertion time, fibreoptic assessment of the airway view and airway morbidity. The first attempt success rate was higher (98%) with the direct technique than with the rotational technique (75%; p = 0.002) but insertion time was faster with the latter method (mean [range] 15 [8-50] s) than with the direct method (20 [8-56] s; p = 0.035). Fibreoptic assessment and airway morbidity were similar in both groups. We conclude that the SSLM can be successfully inserted without intra-oral digital manipulation.

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ObjectiveThe aim of this study was to compare the limb occlusion pressure (LOP) determination and arterial occlusion pressure (AOP) estimation methods for tourniquet pressure setting in adult patients undergoing knee arthroplasty under combined spinal-epidural anesthesia.MethodsNinety-three patients were randomized into two groups. Pneumatic tourniquet inflation pressures were adjusted based either on LOP determination or AOP estimation in Group 1 (46 patients, 38 female and 8 male; mean age: 67.71 ± 9.17) and Group 2 (47 patients, 40 female and 7 male; mean age: 70.31 ± 8.27), respectively. Initial and maximal systolic blood pressures, LOP/AOP levels, required time to estimate AOP/determinate LOP and set the cuff pressure, initial and maximal tourniquet pressures and tourniquet time were recorded. The effectiveness of the tourniquet was assessed by the orthopedic surgeons using a Likert scale.ResultsInitial and maximal systolic blood pressures, determined LOP, estimated AOP, duration of tourniquet and the performance of the tourniquet were not different between groups. However, the initial (182.44 ± 14.59 mm Hg vs. 200.69 ± 15.55 mm Hg) and maximal tourniquet pressures (186.91 ± 12.91 mm Hg vs. 200.69 ± 15.55 mm Hg) were significantly lower, the time required to estimate AOP and set the tourniquet cuff pressure was significantly less (23.91 ± 4.77 s vs. 178.81 ± 25.46 s) in Group II (p = 0.000). No complications that could be related to the tourniquet were observed during or after surgery.ConclusionTourniquet inflation pressure setting based on AOP estimation method provides a bloodless surgical field that is comparable to that of LOP determination method with lower pneumatic inflation pressure and less required time for cuff pressure adjustment in adult patients undergoing total knee arthroplasty under combined spinal epidural anesthesia.

We conclude that TKA operations with a tourniquet application at lower inflation pressures might minimize the complications of tourniquet use and the patients can gain more rapidly early functional mobility.

Clinical utilization of the AOP estimation formula is a practical and effective way of setting tourniquet pressures for lower limb surgery. Its usage allows achievement of a bloodless field with inflation pressures lower than those previously recommended in the literature for lower limb tourniquets.

In a randomized, double-blind, controlled study, we compared heparinized and nonheparinized infusions for the maintenance of perioperative arterial catheter patency and the incidence of subsequent radial arterial occlusion. Two-hundred patients were randomized into 2 groups to receive heparinized (group H, n = 100) or nonheparinized (group S, n = 100) flush solutions. Radial and ulnar blood flows were assessed using Doppler probe and pulse oximetry before, just after, and 24 h after decannulation by the same investigator. The cannulation site was examined for complications such as hematoma, nerve injury, and infection. The mean duration of cannulations was 378 +/- 159.0 min in group H and 332 +/- 154.6 min in group S. The mean number of corrective interventions caused by dampening of the pressure wave (mean number of positional changes [group S, 1.5 +/- 2.0; group H, 1.4 +/- 3.8] and mean number of manual flushes [group S, 1.3 +/- 1.7; group H, 1.2 +/- 1.2]) was not significantly different in both groups. After decannulation, partial or total occlusion developed in 20 group H patients and 16 group S patients (not significant). The incidence of occlusion was correlated to the presence of hematoma at the puncture site after decannulation (P = 0.013), long duration of cannulation (P = 0.04), and age <65 yr (P = 0.009). In conclusion, there is no significant difference between heparinized and nonheparinized flush solutions for the maintenance of perioperative radial artery catheter patency.