Clean technique for prolonged nonsurvival cardiothoracic surgery in swine (Sus scrofa).

Any successful surgical procedure must accomplish the goals of the operation while minimizing surgical complications, one of the most serious of which is sepsis. Sepsis has been defined as “the systemic inflammatory response syndrome [that] is the result of a confirmed infectious process.”5 Sepsis has multiple causes, but one of the most common is bacteremia, the presence of viable bacteria in the blood. Because bacteria gain access to inner tissues and blood with any disruption of dermal integrity, such as occurs during surgery, measures must be taken to prevent perioperative bacterial contamination. These measures collectively are known as aseptic technique: the methods and practices that prevent cross-contamination during surgery.12 Although aseptic technique is the standard of care for survival surgeries in animals, laboratory animal science regulations and literature provide little guidance regarding the type or duration of nonsurvival surgery that requires the use of aseptic surgical technique. The Guide for the Care and Use of Laboratory Animals16 acknowledges that all of the procedures listed for aseptic technique during survival surgeries may not be necessary for nonsurvival procedures; however, “at a minimum, the surgical site should be clipped, the surgeon should wear gloves, and the instruments and surrounding area should be clean.” Otherwise, the language is vague: “For nonsurvival procedures of extended duration, attention to aseptic technique may be more important in order to ensure stability of the model and a successful outcome.”16 The American College of Laboratory Animal Medicine Position Statement on Rodent Surgery2 simply states that all rodent survival surgery should incorporate aseptic technique and makes recommendations for how the attending veterinarian or designee, laboratory animal medicine specialists, and the IACUC should contribute to the formulation of institutional rodent surgical standards and standards for the qualification and training of personnel involved in survival surgery or perioperative care. However, this statement does not address nonsurvival surgery or surgeries in nonrodent species. Regarding survival surgery, the Guide for the Care and Use of Laboratory Animals16 states that inadequate or incorrect aseptic technique may lead to subclinical infections causing physiologic and behavioral changes that can influence “surgical success, animal well-being, and research results.” Therefore, aseptic technique is required for survival surgery in any laboratory animal species, to protect against postoperative infection. The Animal Welfare Act and Regulations3,4 simply state that personnel at research institutions involved in animal care and use must receive adequate training for their duties, including training in aseptic surgical methods and procedures and instruction on “research or testing methods that minimize or … limit animal pain or distress.” At our institution, rodent survival surgery requires sterilized instruments; a clean, uncluttered surgical space dedicated to surgery for the duration of the surgical procedure(s); and a separate preparation area. The surgical site is prepared by removing hair and cleaning with alternating alcohol and antiseptic solution. The surgeon must wear a clean lab coat, gown, or scrubs; a face mask; and sterile surgical gloves during surgery. Survival surgery on USDA-regulated species requires sterilized instruments and a dedicated surgical suite that includes the operating room and separate areas for animal preparation, surgeon preparation, and animal recovery. The surgical site is prepared by removing hair and cleaning with alternating alcohol and antiseptic solution. The surgeon must wear facility scrubs, a sterile surgical gown, a face mask, shoe covers, and a hair bonnet during surgery. In addition, the surgeon must perform a thorough hand scrub prior to donning sterile surgical gloves for rodent survival surgery. For nonsurvival surgery on any species at our institution, surgeon attire and patient preparation must be described in the protocol, but strict aseptic technique typically is not required, and some procedures may instead be conducted in a ‘clean’ manner. However, clear guidance is not available for nonsurvival surgeries of extended duration, and standards for these surgeries are determined on a case-by-case basis. With the current project, we sought to address the use of clean technique for nonsurvival surgery. We hypothesized that swine that underwent nonsurvival cardiothoracic surgery by using clean technique would show no evidence of bacteremia or sepsis, even after an extended duration (8 h). The goal of the current study was to test this hypothesis by evaluating serial blood cultures and patient clinical parameters, including hematologic and clinical chemistry profiles, for evidence of bacteremia or sepsis at regular time points after the initiation of nonsurvival cardiac surgery in swine. These results are intended to provide new and more specific information relevant to the acceptability of clean technique during prolonged nonsurvival surgeries.