Chris S. Burrows

Objective: To quantify compliance with chlorhexidine surgical site disinfection (SSD) contact time protocols across 5 veterinary hospitals. Methods: A prospective observational study recorded chlorhexidine SSD contact times, defined as the interval between initial application and removal, in 201 SSD episodes across 5 hospitals. A single but different investigator collected data at each site, with staff blinded to the study’s purpose to minimize bias. Results: A total of 201 SSD episodes were recorded across 5 hospitals. The number of SSD episodes per hospital was 32, 65, 29, 62, and 13 for hospitals 1, 2, 3, 4, and 5, respectively. The overall compliance rate with the target 3- to 5-minute contact time was 70.15%, with significant interhospital variability (35.39% to 100%). Conclusions: Significant variability in SSD protocol compliance exists among veterinary hospitals, with a substantial portion of episodes failing to meet minimum contact time requirements. Both insufficient and excessive contact times may increase the risk of surgical site infections. Further research is warranted to identify factors influencing noncompliance and develop strategies to improve adherence. Clinical Relevance: Improved awareness and further research on SSD protocol compliance are crucial for optimizing patient outcomes by reducing surgical site infection risk.

Considerable research is being undertaken to develop novel biomaterials-based approaches for surgical reconstruction of bone defects. This extends to three-dimensional (3D) printed materials that provide stable, structural, and functional support in vivo . However, few preclinical models can simulate in vivo human biological conditions for clinically relevant testing. In this study we describe a novel ovine model that allows evaluation of in vivo osteogenesis via contact with bone and/or periosteum interfaced with printed polymer bioreactors loaded with biomaterial bone substitutes. The infraspinous scapular region of 14 Dorset cross sheep was exposed. Vascularized periosteum was elevated either attached to the infraspinatus muscle or separately. In both cases, the periosteum was supplied by the periosteal branch of the circumflex scapular vessels. In eight sheep, a 3D printed 4-chambered polyetheretherketone bioreactor was wrapped circumferentially in vascularized periosteum. In 6 sheep, 12 double-sided 3D printed 2-chambered polyetherketone bioreactors were secured to the underlying bone allowing direct contact with the bone on one side and periosteum on the other. Our model enabled simultaneous testing of up to 24 (12 double-sided) 10 × 10 × 5 mm bioreactors per scapula in the flat contact approach or a single 40 × 10 mm four-chambered bioreactor per scapula using the periosteal wrap. De novo bone growth was evaluated using histological and radiological analysis. Of importance, the experimental model was well tolerated by the animals and provides a versatile approach for comparing the osteogenic potential of cambium on the bone surface and elevated with periosteum. Furthermore, the periosteal flaps were sufficiently large for encasing bioreactors containing biomaterial bone substitutes for applications such as segmental mandibular reconstruction.

The transversus abdominis plane (TAP) block is an ultrasound guided regional anaesthetic technique used to provide analgesia to the abdominal wall. Research in humans and cats has demonstrated that TAP blocks reduce pain and post-operative opioid requirements after abdominal surgery. To date TAP blocks have not been described in rats. The optimal technique to employ when performing TAP blocks is controversial with single point injection techniques failing to reliably provide adequate coverage of the cranial abdominal wall. It has been suggested that performing a two point injection may provide more reliable coverage of the cranial abdominal wall. The objective of this study was to determine the feasibility of performing ultrasound guided TAP blocks in rat cadavers and to evaluate whether performing a two point technique provides greater spread of injectate than a one point technique when administering the same total volume of methylene blue solution. Twenty-three, four-month-old, female Sprague Dawley rat cadavers weighing 506 ± 78 g were used. TAP blocks were performed using a total of 1 ml/kg of methylene blue solution. Overall success rates for injections were 21.7% (13.6–32.8%). Single point injection area of spread was 87.8 ± 32 mm² compared with 102.4 ± 17 mm² for the two point injection technique. Due to the low success rate the use of TAP blocks using the current technique cannot be recommended. Two point injection technique appears to provide greater spread; however, additional data is required to draw meaningful conclusions.