SLR - February 2021 - Milad Adloo

Timing of Antimicrobial Prophylaxis and Tourniquet Inflation: A Randomized Controlled Microdialysis Study

Reference: Hanberg P, Bue M, Öbrink-Hansen K, Thomassen M, Søballe K, Stilling M. Timing of Antimicrobial Prophylaxis and Tourniquet Inflation: A Randomized Controlled Microdialysis Study. J Bone Joint Surg Am. 2020 Nov 4;102(21):1857-1864. doi: 10.2106/JBJS.20.00076. PMID: 32769808.

Level of Evidence: Level III – Randomized Controlled Study

Scientific Literature Review

Reviewed By: Milad Adloo, DPM
Residency Program: NYU Langone Hospital – Brooklyn, NY

Podiatric Relevance: Tourniquets are widely used in podiatric surgery to reduce perioperative bleeding and to improve visualization of the surgical field. Surgical site antibiotic prophylaxis is a crucial element of lower extremity surgery, and correct timing of the administration of antibiotics and tourniquet inflation is critical to ensure adequate tissue concentrations. There is no guideline or consensus in the literature regarding administration of antibiotics prior to tourniquet inflation. The aim of the study was to evaluate the time for which free drug concentration of cefuroxime was maintained above the minimum inhibitory concentration (MIC) in porcine subcutaneous adipose tissue and calcaneal cancellous bone.

Methods: Microdialysis was employed to assess concentrations of antibiotics in the tissue. Twenty-four female Danish Landrace pigs were used in the study, kept under general anesthesia, and kept at normal levels of pH, temperatures, hydration, and glucose. With the pig in supine position, both calcanei were exposed utilizing a longitudinal plantar incision. A drill-hole was made from the inferior part of the calcaneocuboid joint to the proximal part of the calcaneus. Catheters were placed in the drill-holes and also in the subcutaneous adipose tissue of the plantar sides of both hind feet. Tourniquets were randomly applied on the right or left leg, and then each pig was randomized into one of three groups: 1.5g cefuroxime administered 15 minutes prior to tourniquet inflation (Group A), 45 minutes prior to inflation (Group B), and at the time of tourniquet release (Group C). Duration of tourniquet inflation was 90 minutes in all three groups. A total of 12 dialysates from each catheter was collected over an 8-hour period.

Results: Cefuroxime concentrations were maintained above t > MIC for Staphylococcus aureus in calcaneal cancellous bone and subcutaneous adipose tissue throughout the 90-minute tourniquet duration for Groups A and B and for approximately 1 hour after tourniquet release. Cefuroxime administration in Group C resulted in t > MIC for approximately 3.5 hours in both adipose and calcaneal bone on the limb with tourniquet application. There were no significant differences in t > MIC in either type of tissue between the three groups. 

Conclusions: The authors claim that this is the first study of its kind to investigate cefuroxime concentrations in subcutaneous adipose tissue and calcaneal cancellous bone before, during, and after tourniquet inflation in legs with and without a tourniquet but it is important to note this study was performed in animals not human limbs. The main finding was that antibiotic concentrations were maintained above the clinical breakpoint for MIC of Staph aureus throughout the 90-minute tourniquet duration in Groups A and B, as well as for 3.5 hours on the tourniquet limb for Group C. These findings echo results in previous studies. Ultimately the results demonstrate that Group C had higher peak drug concentrations with increased tissue penetration compared to Groups A and B. This article can help surgeons to apply this information towards clinical decision-making for optimizing antibiotic delivery to surgical sites.

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