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To the Editor:—
At the University of Louisville, the Human Patient Simulator (METI, Sarasota, FL) and other simulation models are used for the training of anesthesiology residents. Although the simulator can provide excellent training models in the form of case scenarios, we have discovered that when a central venous or pulmonary artery catheter is required, we cannot simulate the actual placement of the catheter. Learning to be facile in the placement of these monitors is essential to the residents’ training. That facility includes tray preparation (filling the wells with heparinized saline, arranging the syringes and needles), setting up the transducers, preparing the patient, and using the proper sequence of steps to locate and cannulate the vessel. We believe that the more physicians in training practice these procedures, the greater their skills will be at performing them. In most institutions, these skills are acquired by regularly performing the procedures on actual patients. The skill of a resident, therefore, is dependent on the opportunities he or she has to attempt central venous monitor placement. A device that allows a trainee to practice these procedures regularly in a realistic, nonthreatening environment would therefore be beneficial in the acquisition of these skills.
We have developed a device with which the residents can practice central venous catheter placement using the human patient simulator as the human interface. The device, composed of varying sizes of tubing attached to a reservoir filled with artificial blood, simulates either the internal jugular or subclavian vein (fig. 1). The device accepts a J-wire, a triple lumen catheter, an introducer, and a pulmonary artery catheter. The device is placed underneath the skin of the human patient simulator in the anatomically appropriate locations (fig. 2). Using this device, the trainee can perform essentially all of the steps, in their proper sequence, in placing a central venous monitor (the suturing of the catheter to the skin is omitted). The vein can be located using anatomic landmarks (e.g. , palpating the carotid pulse) and punctured with a seeker needle to reveal a “flash” of artificial blood. Following this step, the Seldinger technique can be used to place either a triple lumen catheter or introducer. Proper placement of the catheter can be confirmed by the aspiration of “blood.” While the catheter is being placed, the simulator operator can simulate events such as premature ventricular contractions with J-wire placement. For the passage of a pulmonary artery catheter, the location of the balloon within the vasculature may be simulated by the resident's notifying the simulator operator of the distance of the catheter tip from the entrance point of the introducer. As the catheter is advanced, the correlating waveforms, up to the wedge position, may be transmitted to a monitor. This provides additional training in recognizing right-sided cardiac pressure waveforms. The device may also be connected to a reservoir via a stopcock to accommodate the infusion of simulated drugs or fluids. Another benefit of this device is the opportunity to learn and practice procedure tray setup before starting the procedure. Proper tray setup improves economy of motion during the catheter placement steps, which reduces total procedure time. Although we recognize that this step could theoretically be practiced in isolation without the need for our device, we believe the educational utility of doing so without actually performing the procedure would be limited.
Fig. 1. Assembled device unfilled with blood prior to attachment to stopcock and intravenous bag/tubing assembly.
Fig. 1. Assembled device unfilled with blood prior to attachment to stopcock and intravenous bag/tubing assembly.
Fig. 2. Model C of the human patient simulator (METI) demonstrating the locations of the device at the left subclavian and right internal jugular veins. The skin has been removed for visualization.
Fig. 2. Model C of the human patient simulator (METI) demonstrating the locations of the device at the left subclavian and right internal jugular veins. The skin has been removed for visualization.
In addition, because the training is being performed on a mannequin, training can be done at a controlled pace with necessary teaching interruptions without the concern of patient stress or prolonging operating room time. This reduces the stress level experienced by both the trainee and trainer, and thereby improves the quality of the learning environment. We have informally used our device with medical students, residents, and attending physicians, all of whom have expressed very positive responses regarding its utility as a teaching tool. The residents noted that it was particularly helpful in teaching them economy of motion as well as the sequence of steps involved in the procedure. For more experienced trainees, scenarios could be run to test the management of various complications (e.g. , recognizing and managing complete heart block during pulmonary artery catheter placement in a patient with a preexisting left bundle branch block).
For those institutions that have a human patient simulator, our device allows for the duplication of essentially all of the steps involved in performing central venous catheterization and pulmonary artery catheter placement. It could therefore be an excellent training tool, particularly for those inexperienced in performing these procedures. We are currently evaluating with a formal study the educational utility of our device to determine whether the skills learned on the simulator are transferred when applied to an actual patient. Additional information regarding this is available on the Anesthesiology Web site.
