1. Umbilical Cord Model for Umbilical Vein Catheterization Training Tim Balgemann, Padraic Casserly, Angwei Law, Kelvin Ng, Ann Sagstetter Client: Dr. Julie Kessel, Department of PediatricsAdvisor: Dr. Brenda Ogle, Department of Biomedical Engineering BACKGROUNDMotivation Many infants suffer trauma during delivery and often require immediate catheterization through the umbilical vein for resuscitation. Such a procedure is difficult and stressful, demanding training for clinicians in the delivery room. The American Academy of Pediatrics Neonatal Resuscitation Program (NRP) conducts such training several times a year. However, current training models are inadequate at simulating the procedure. A more realistic model is hence needed. Cord-In-Gel Model Umbilical cord is suspended in sandpaper-coated Playtex liner Knox Gelatin is made to 3 units of concentration and poured into liner (1 unit = 1 packet / 150 ml) Entire system is cooled at 4°C overnight Bottom of liner and part of cord are cut to expose cross section of cord that is not infused with gelatin Cut liner (with cord) is inserted into a second liner which acts as a blood reservoir Entire system is finally inserted into a foam support so that catheterization can proceed Sphygmomanometer Model A Neonate-3 blood pressure cuff is fixed in a special-needs feeder (a plastic cylindrical bottle) Strips of sandpaper is glued to cuff interior to improve friction between cord and cuff, reducing chance of slipping Cuff can be inflated externally by a syringe Umbilical cord is inserted into lumen of cuff, and cuff is inflated to hold cord in place Feeder serves as a blood reservoir Entire system is finally inserted into a foam support so that catheterization can proceed ABSTRACT The goal of this design project is to develop a realistic training model that can be used for umbilical vein catheterization training, incorporating real human umbilical cords. Two aspects are of primary concern: the stability of the umbilical stump, and the external texture of the infant abdomen. Currently, there are two existing models in the market which have been deemed unsatisfactory due to inadequate mimicry of the umbilical cord placement. Our design hence seeks to create a model that is better at mimicry, safe, user-friendly and affordable. Two prototypes, the cord-in-gel model and the sphygmomanometer model, have been developed to date. Anatomy & Umbilical Vein Catheterization The umbilical cord consists of two arteries and a vein, surrounded by Wharton’s jelly. During resuscitation, a 3.5-F or 5-F catheter is inserted into the umbilical vein, which branches into the liver and inferior vena cava (Figure 1). The depth of insertion is approximately 5 cm beyond the umbilicus. Such a procedure is painless and offers direct access to the infant’s circulatory system. PROBLEM STATEMENT To construct a model optimized in the following ways for use in the umbilical vein catheterization training program: firmly stabilize a fresh umbilical cord accurately mimic the external texture of an infant’s abdomen CURRENT PRODUCTS Currently, there are two models addressing the NRP’s training protocol: 1)Baby Umbi by Laerdal (Figure 2) 2)NRP Baby Bottle Model (Figure 3) CONCLUSION Using real umbilical cords, both the cord-in-gel model and the sphygmomanometer model provide more realistic training than Baby Umbi. In addition, both prototypes have proven to be better than the NRP baby bottle model in terms of the success of catheterization and the stabilization of the cord. This is supported by results from the tensile and catheterization tests that were carried out. One factor was identified to be beyond the user’s control in terms of the success of catheterization. Umbilical veins in different cords have different degrees of twisting, which can possibly confound the outcome of the catheterization tests. In future experiments, larger sample sizes could be used to reduce the random error caused by this problem. Currently, both models are sufficient in meeting the design criteria, but excel at different aspects. The cord-in-gel model performs better at mimicking the umbilicus, while the sphygmomanometer model is more user-friendly in terms of its preparation. Though the latter is weaker at stabilization and mimicry, the team believes that it has greater commercial potential and can be optimized to perform as well as, if not better than, the cord-in-gel model. FUTURE WORK Optimize the current models Identify the superior model Focus on mimicking the anatomical course of the umbilical vein after entry into the umbilicus Refine the construction process of the model for bulk manufacturing Search for materials better suited for bulk manufacturing Conduct blind testing with trainees in a real NRP umbilical vein catheterization training session REFERENCES Neonatal Resuscitation Program. American Academy of Pediatrics. Oct 15, 2007. http://www.aap.org/nrp/images_z_nu/tnr5_f62_veinousumbillical.jpghttp://www.aap.org/nrp/images_z_nu/tnr5_f62_veinousumbillical.jpg Baby Umbi. Laerdal. Sep 14, 2007. http://www.laerdal.com.auhttp://www.laerdal.com.auACKNOWLEDGEMENTS We thank Dr. Brenda Ogle and Dr. Julie Kessel for their guidance throughout the course of this project. We also appreciate Sharon Blohowiak’s assistance with laboratory procedures. OUR DESIGN Model Assessment & Comparison Tensile Test: Tensile Test: All models (including the NRP baby bottle model) were subjected to a tensile test using a Newton meter to measure the force required to uproot the cord from the “umbilicus”. Results are shown in Figure 6. Catheterization Test: Catheterization Test: All models (including the NRP baby bottle model) were catheterized using different sections from the same umbilical cord to compare the success of catheterization using our models compared to the NRP baby bottle model (Figure 7). Figure 1: Figure 1: Insertion of catheter into umbilical vein Figure 2: Figure 2: Baby Umbi by Laerdal Figure 3: Figure 3: NRP Baby Bottle Model Figure 4: Figure 4: Cord-In-Gel Model Figure 5: Figure 5: Sphygmomanometer Model Figure 6: Figure 6: Tensile Test Results Figure 7: Figure 7: Catheterization Test Results