Is There Room to Improve Surgical Skills and Training in Rodents?

Fri, 04/18/2014 - 8:20am
Szczepan Baran, Elizabeth Johnson, and Matthew Flegal

The impact of anatomical knowledge, competency assessment, surgeon’s experience, fatigue, and workload on the final experimental outcome.

Mice are the most prevalent animal utilized within the biomedical field, and, in the early 1980s, the development of transgenic technologies which lead to the availability of genetically engineered mice further expanded their usefulness within fields of immunology, oncology, physiology, pathology, and neuroscience. For many studies within these fields, there is a need for blood and other bodily fluid collection, as well as the intravenous infusion of investigational compounds.

As the scientific areas of infusion technology and surgical model development continue to grow, they will allow for continual improvement and refinement of techniques. New technologies can potentially introduce confounding factors (variables), which should be limited whenever possible. Surgery is an inherent part of infusion procedures, and it is important to recognize that surgical procedures disturb normal physiology thereby introducing confounding factors.

The stress response following surgery includes hormonal and metabolic changes. This stress response is directly proportional to the level of trauma (surgery) and can last for up to nine days. Post-surgical stress response also includes increase in oxygen demand, increase in pulmonary and renal workload, and impairment of gastrointestinal motility and immune function.

Many aspects of surgery can be refined to decrease the effect of or limit the number of confounding factors. These aspects include the utilization of appropriate magnification and illumination,1 the use of appropriate surgical suture and needles,2 proper ergonomics and instrument handling,3 using aseptic technique,4,5,6 the proper selection of vascular catheters,7 the use of anti-thrombic filling solutions and equipment,8 and the specific surgical technique itself. This article addresses the impact of efficient anatomical knowledge, competency assessment, surgeon’s experience, and fatigue and workload on the final experimental outcome.

Anatomy courses are part of the early curriculum within veterinary and medical schools so that when students move into surgical rotations they have the foundation to understand the impact that surgical procedures have on the patient.

The topic of anatomy has recently received a lot of attention in both human and veterinary surgical training that utilize cadavers for dissection. The primary reason for this attention is the attempt to reduce the number of cadavers required for the study of anatomy and surgical techniques and replacing them where possible with inanimate models, problem-based workshops, books, and online modules which are now being introduced into the curriculum.9

One of the supportive arguments for the use of cadavers is surgical error reports which suggest that many surgical iatrogenic injuries could be prevented if surgeons had better anatomical knowledge.

The challenge within the laboratory animal science field is that rodent surgery is commonly performed by personnel without any veterinary, medical, or formal surgical backgrounds performing high-throughput surgical studies. During advanced catheterization and hemodynamic workshops, students who were asked to identify specific vessels or describe vessel anatomy were able to do so 33.5% of the time and when questioned about vascular regional anatomy only 21.5% were able to describe it correctly. When asked about the physiological impact that manipulation or trauma to specific nerves or vasculature might have, only 12.3% could answer correctly. A solid working knowledge of anatomy and physiology facilitates gentle surgical technique which can prevent injuries due to inadvertent transection, ligation, or trauma to the vessel and other important anatomic structures. This in turn will also limit variability in the surgical outcomes due to trauma and variable catheter placement. Research indicates that even a basic vascular technique such as tail vein injections can have a significant impact on the outcome of a study when performed poorly.18 Therefore it is imperative that personnel performing surgical catheterizations are familiar with the anatomy and physiological impacts of the surgery. Basic knowledge of anatomic structures and landmarks should be standardized and assessed prior to performing any surgical procedure. Personnel determined to lack this knowledge should not be approved to perform catheterization procedures. In order to implement these standards, objective competency assessment tools must be implemented.

Competency Assessment
Assessment of surgical competency is a vital component of surgical training because it confirms that the surgeon has the knowledge, skill, and ability to perform the surgery. An objective and standardized surgical assessment program can serve as one tool to ensure that high surgical standards are met through training which can decrease research variables and improve animal welfare. Currently, most personnel are approved to perform catheterization procedures because: 1) they state on their protocol submission that they have experience with these procedures, 2) they have been assessed by another researcher, and/or 3) a certain specified percentage of their animals survive without obvious complications and the catheters are patent for a specific period of time.

The challenge with these assessments is that they are subjective, can only catch obvious gross complications, and do not allow for identification of the flawed area of the procedure which caused the complication(s). Objective competency assessment tools and development have been recently described in surgery14,15,16 and biomethdology17 in the LAS field.

Competency and its assessment is becoming one of the most hotly debated topics engaging the profession, especially due to updates to the European Directive and the Guide for the Care and Use of Laboratory Animals. In the current climate of longer working hours and the reduced or even absence of hands-on training, the laboratory animal science and medical communities are having to address the complex issue of how various techniques and procedures should be taught and how to assess individual competency and reassessment.

There is public, political, and regulatory pressure upon the LAS profession to improve animal welfare within which surgical training and competency assessment play a significant role. With the limited funding and time for surgical training available to personnel performing catheterization and other surgical procedures, assessment is becoming even more important.

Surgeon’s Experience It is often asked “how many times should a trainee perform a procedure before they become competent in that procedure?” This is a challenging and often emotionally charged question with very little published data available on this topic. However it has been demonstrated that surgical experience does matter and has a significant impact on mortality and morbidity.10,11,12,20 One of the challenges is that personnel performing these procedures can have very diverse backgrounds; from high school graduates to postdoctoral students. While academic training is a great advantage to understand surgical concepts, it is no substitute for actual hands-on practice and training.

The amount of surgical experience to perform catheterization procedures is commonly underestimated, which often results in having someone who has attended a 1-2 day workshop on catheterization procedures be expected to immediately begin performing study catheterization procedures upon their return. In the authors’ experience, even when we include objective competency assessment during our workshops, students still require substantial practice on their own before they would be signed off as competent for the procedure. The recommendation is thus for them to go back to their facilities and practice the procedure and then subsequently undergo another competency assessment. Therefore, the statement “practice makes perfect” applies in this scenario to minimize trauma and variability as well as wasting animal lives’ with failed procedures.

Workload and Fatigue
Personnel preforming rodent infusion catheterization procedures may perform up to 30 individual surgical procedures within the same day, and this can continue for days at a time. It has been shown that the risk of surgical complications is associated with the number of daily surgical hours19 and that surgical technique will degrade with fatigue. This is exacerbated when surgeons don’t take breaks. Finally, rodent surgical stations are frequently poorly designed to reduce fatigue with appropriate micro-surgical instruments, appropriate ergonomic table height, and so forth. In the authors’ experience, a noticeable reduction of complications and failed surgical procedures can result by enforcing appropriate short breaks and the use of a well designed work-station.

Implementation of teaching anatomy, objective competency assessment, planning, and provision to practice catheterization procedures will lead to improvement of surgical standards, decrease mortality and morbidity, decrease confounding factors, provide better data, and improve animal welfare.

1. Refining Rodent Surgery Through Magnification & Illumination
2. Understanding and Selecting Surgical Suture and Needle
3. Ergonomic and Proper Handling of Surgical Instruments
4. Infusion Tips: Keep It Sterile Surgeon, Part 1: Pre-operative Surgical Preparation
5. Infusion Tips: Keep It Sterile Surgeon, Part 2: Methods to reduce contamination during catheterization surgery
6. Infusion Tips: Keep It Sterile Surgeon, Part 3: Aseptic Maintenance of Vascular Access Catheters
7. Infusion Tips: The Three Rs of Catheters: Reliability, Resistance, and ROI
8. Advances in Laboratory Animal Infusion and Sampling
10. Hannan EL, Siu AL, Kumar D, Kilburn H Jr, Chassin MR. The decline of coronary artery bypass graft surgery mortality in New York State:The role of surgeon volume. JAMA 1995;273:209-13.
11. Sosa JA, Bowman HM, Tielsch JM, Powe NR, Gordon TA, Udelsman R. The importance of surgeon experience for clinical and economic outcomes from thyroidectomy. Ann Surg 1998;228:320-30.
12. Ruby ST, Robinson D, Lynch JT, Mark H. Outcome analysis of carotid endarectectomy in Connecticut: the impact of volume and specialty. Ann Vasc Surg 1996;10:2226.
13. Introduction to Rodent Surgery: Tips for more successful procedures
14. W-20 Sew You Learned to Tie a Knot, But Did You? Competency Assessment Explained.
15. How to Develop Competency Assessment
16. Baran SW, Johnson EJ; Kehler J, Hankenson FC. Development and Implementation of Multimedia Content for an Electronic Learning Course on Rodent Surgery. Journal of the American Association for Laboratory Animal Science, Volume 49, Number 3, May 2010 , pp. 307-311(5)
17. Clifford P, Melfi N; Bogdanske J, Johnson EJ, Kehler J, Baran SW. Assessment of Proficiency and Competency in Laboratory Animal Biomethodologies. Journal of the American Association for Laboratory Animal Science, Volume 52, Number 6, November 2013 , pp. 711-716(6)
18. Groman, Ernest V.; Reinhardt, Christopher P. Method to Quantify Tail Vein Injection Technique in Small Animals. Journal of the American Association for Laboratory Animal Science, Volume 43, Number 1, January 2004 , pp. 35-38(4)
19. Thomas M, Allen MS, Wigle DA, Shen KR, Cassivi SD, Nichols FC 3rd, Deschamps C. Does surgeon workload per day affect outcomes after pulmonary lobectomies? Ann Thorac Surg. 2012 Sep;94(3):966-72. Epub 2012 Jun 8.
20. J Vasc Sur. 2008 Aug;48(2):343-50; discussion 50. doi: 10.1016/j.jvs.2008.03.033. Statistical modeling of the volume-outcome effect for carotid endarterectomy for 10 years of a statewide database. Nazarian SM, Yenokyan G, Thompson RE, Griswold ME, Chang DC, Perler BA.

Szczepan Baran, VMD, MS is the President for the Veterinary Bioscience Institute. Piedmont Triad Research Park, 415 East 3rd Street, A1a Building, Winston-Salem, NC 27157. He can be reached at;

Elizabeth Johnson, VMD is the CEO for the Veterinary Bioscience Institute, Piedmont Triad Research Park, 415 East 3rd Street, A1a Building, Winston-Salem, NC 27157. She can be reached at

Matthew Flegal, BS, SRS is Manager of the Surgical Services at the Department of Comparative Medicine at the Genzyme Corporation, 500 Kendall Street, Cambridge, MA 02142. He can be reached at


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