Microsurgical Training Using a Pulsatile Membrane Pump and Chicken Thigh: A New, Realistic, Practical, Nonliving Educational Model

Abstract

Sir: Microsurgery requires practice, skill, and patience. Numerous microsurgical training models are available that can impart skill, given an appropriate level of rehearsal. Models can range from basic (e.g., Silastic tubing) to live animal models. Increasingly, more realistic nonlive models have been developed that provide a high-fidelity training experience. We propose a pulsatile nonvital chicken thigh model for use in training. The core technology of this model is the membrane pump. The pump is a commercially available Rietschle-Thomas (Sheboygan, Wis.) membrane pump model FZ 5002. Standard intravenous 0.9% normal saline is used to perfuse the model. Our microsurgical training setup is shown in Figure 1. The pump provides a pulsatile pressure wave comparable to normal human parameters (60 to 120 mmHg). The pump's flow parameters simulate a normal peripheral pulsatile arterial flow ranging from 0 to 0.85 liters/minute. (SeeVideo, Supplemental Digital Content 1, demonstrating pulsatile flow through a transected chicken femoral artery attached to the membrane pump, https://links.lww.com/PRS/A232.)Fig. 1.: The microsurgical training workstation, including microsurgical instruments, microscope, liquid crystal display monitor, DC power supply, membrane pump, drip tray, and operative field.Video 1.: Supplemental Digital Content 1 demonstrates pulsatile flow through a transected chicken femoral artery attached to the membrane pump, https://links.lww.com/PRS/A232.Fresh chicken thighs are used. The femoral artery is cannulated using a 22-gauge cannula. An H-shaped incision is made over the iliotibialis, iliofibularis, gastrocnemius, and peroneus longus muscles. Flaps are raised and the muscles either reflected or resected until the neurovascular plane is identified, as shown in Figure 2. Bipolar diathermy is required for cautery of the tributaries of the artery and vein, adding to the realism of the model. Dissection requires delicate handling of the tissues and respect for branching and perforating vessels. (See Video, Supplemental Digital Content 2, which demonstrates arterial side branches arising from the chicken femoral artery, https://links.lww.com/PRS/A233.) Poor technique will result in simulated bleeding. A number of anastomotic techniques can now be preformed. (See Video, Supplemental Digital Content 3, which demonstrates a pulsatile arterial anastomosis, https://links.lww.com/PRS/A234.)Fig. 2.: Neurovascular bundle following dissection.Microsurgical skill is best attained by exposure through a graduated progression from simple to more advanced training models.1,2 There are numerous beginner and advanced models3 but a real paucity of realistic, intermediate level, nonliving models. The technique of using a pulsatile membrane pump in microsurgical training was first described by Schoffl et al.4 using porcine coronary arteries. We have found that there are two significant drawbacks with this original method. First, coronary vessels are intimately adherent to the myocardium and have numerous side branches that complicate the dissection. Second, pig hearts do not tolerate refrigeration well, becoming firm and wooden. Chicken thighs, in comparison, are still supple and realistic to dissect even days after their harvest. The standard means of microsurgical teaching is still live animal training. Anastomoses can be assessed mechanically (i.e., checking for leaks), but also hemodynamically by assessing for thrombosis.5 However, animals are expensive to keep, operate on, and dispose of. Animal ethics approvals are often difficult and time-consuming to obtain. Premature exposure of microsurgical trainees to advanced live animal models can be wasteful if the trainees have not mastered basic technique first. There has been a growing movement toward high-fidelity, nonvital surgical and microsurgical training for some time. A nonliving pulsatile microsurgical model is in keeping with this paradigm. We believe that the pulsatile chicken thigh is the best current adaptation of this model, as it is realistic, easy to obtain, cheap, and lasts well. In the current form, it will not obviate the need for live animal training. However, it will advance trainees' skill levels to a point at which will derive the most benefit when they progress to live animal models. DISCLOSURE The authors have no financial interest to declare in relation to the content of this article. Alexander F. Phoon, M.B.B.S. Graham J. Gumley, F.R.A.C.S., F.A.Orth.A. Michael A. Rtshiladze, M.B.B.S. Sydney Hospital Microsurgical Laboratory Sydney Hospital Hand Unit, and University of Sydney Sydney, New South Wales, Australia