Keanu Chan
Age 13 | Cranbrook, British Columbia
Canada-Wide Science Fair 2019 Excellence Award: Junior Bronze Medal
Western University $1000 Entrance Scholarship
Introduction
Traumatic injuries contribute to approximately one in ten mortalities, accounting for more than 5.8 million deaths worldwide each year (1,2). Uncontrolled bleeding from trauma is the leading cause of potentially preventable death among injured patients. Prompt measures to minimize blood loss and achieve haemodynamic stability is crucial to improve outcomes in the trauma patient. Last year, I worked to develop a device under the acronym HEALIT: Hemostasis by Expanding Automatic Life-saving Innovative Technique. HEALIT was shown to significantly reduce total rate and volume of blood loss from traumatic wounds by increasing pressure inside the wound. Two new iterations were subsequently developed as HEALIT 2.0 and 3.0. HEALIT 2.0, designed to enhance coagulation inside the wound with different hemostatic materials, and HEALIT 3.0, which was designed to reduce the incidence of wound infection.
HYPOTHESIS
In addition to the bleeding suppression fostered by HEALIT 1.0 and 2.0, I hypothesize that HEALIT 3.0 will not only reduce the amount of bleeding from a wound by enhancing coagulation due to the use of different hemostatic materials, but will concurrently reduce the incidence of infection by the addition of antibiotics.
MATERIALS AND METHODS
HEALIT 1.0
Polyol and Isocyanate solutions were placed into separate breakable vials. One vial of Polyol and one vial of Isocyanate were placed into an expandable pouch. When the pouch is squeezed, the two vials would break allowing the two solutions to mix. Upon mixing, Polyol and Isocyanate undergo a unique chemical reaction that produces an expanding polyurethane foam. The two solutions remain inert when left separated. If clinically implemented, the two solutions would be combined moments before insertion into the bleeding site. Polyurethane foam expansion creates internal pressure to stop the bleeding. A closed circuit, bleeding wound simulation model was designed using a foam block to represent the human body and a mini water fountain pump to act as circulating blood. HEALIT pouches were activated by breaking the Isocyanate and Polyol vials inside and then placed into the bleeding wound. Volume and rate of blood loss was measured by calculating the amount of simulated blood loss from the simulated wound over a set period of time. This was performed with and without the HEALIT pouches applied to the wound.
HEALIT 2.0
In the second iteration, the Polyol and Isocyanate solutions were separated by having one solution in a breakable vial inserted into an enclosed expandable pouch that contained the second solution. When the vial is broken, both solutions come into direct contact and form the expanding polyurethane foam, acting to increase the pressure within the wound. The HEALIT 2.0 pouches were then covered with various hemostatic adjuncts that are marketed to control local hemorrhage:
1. Surgicel Absorbable Hemostat, which is an absorbable knitted fabric prepared by the controlled oxidation of regenerated cellulose (manufactured by Ethicon).
2. Avitene Microfibrillar Collagen Hemostat, which is an active absorbable collagen hemostat which enhances platelet aggregation and the release of proteins to form fibrin (manufactured by BARD).
3. Surgifoam, which is an absorbable gelatin sponge which provides a matrix for platelet aggregation and adhesion (manufactured by Ethicon).
4. Floseal Hemostatic Matrix, which are gelatin granules that swell to produce a tamponade effect and contain high concentrations of human thrombin that converts fibrinogen into fibrin monomers, accelerating clot formation (manufactured by Baxter).
5. Hemopatch, which is a flexible collagen pad coated with NHS-PEG* which provides firm attachment to tissue surfaces while inducing hemostasis (manufactured by Baxter). * pentaeythirol polyethylene glycol ether tetra-succinimidyl glutarate.
Each of the HEALIT 2.0 pouches with one of the five hemostatic adjuncts were then tested to see if they accelerated the clotting time in human blood (Figure 1). Samples of human blood from 20 patients at the local hospital (portions of which were being discarded during an unrelated medical procedure) were tested. Each patient provided informed consent for the use of their blood sample. Control and experimental samples from each patient were separated into two blood test tubes. The hemostatic adjunct was added to the experimental tube. The control tube had no hemostatic adjunct added to it. The time to complete clot formation in the blood sample was measured for both the control and experimental samples.
Figure 1. Preparation of hemostatic agents (A), insertion of hemostatic agent into test tube with blood sample (B), clot formation in test tube (C), and clot after removal from test tube (D).
HEALIT 3.0
In the third iteration, the HEALIT 2.0 pouches were embedded on their surface with an antibiotic powder (Tobramycin) (Figure 2). Tobramycin was enshrouded in each of the hemostatic adjuncts. The HEALIT 3.0 pouches were then placed into the normal saline solution (saltwater concentration similar to human blood) and triggered to expand (Figure 3). The ability for Tobramycin to absorb into normal saline was measured by the percentage volume of the powder that dissolved into the saline solution.
Figure 2. Tobramycin antibiotic (A), and tobramycin powder on Surgicel (B).
Figure 3. HEALIT 3.0 pouches before HEALIT 3.0 expansion (1), after expansion (2), partial submersion in Normal Saline (3), full submersion (4), and after removal from Saline (5).
RESULTS
HEALIT 1.0
The volume of blood loss and the rate of blood loss was measured with and without the application of the HEALIT pouches. The measurements were taken over a 30 second time span. The measurements were repeated 8 times. Figure 4 shows the measurements in a bar graph form. Blood loss was markedly decreased with the use of HEALIT in each of the eight trials.
Statistical Analysis
A paired t-test was used to compare the volume of blood loss and rate of blood loss with and without HEALIT. Statistical analysis indicated that the amount and rate of blood loss significantly decreased with the application of HEALIT. Amount of blood loss without HEALIT (M=654.38, SD=175.28) and with HEALIT (M=166.88, SD=96.14); t(7)=7.57, p=0.0001. Rate of blood loss without HEALIT (M=21.81, SD=5.84) and with HEALIT (M=5.56, SD=3.20); t(7)=7.58, p=0.0001.
HEALIT 2.0
The times to complete clotting of the blood samples were measured for each of the hemostatic adjuncts and compared to a control sample that had no added hemostatic adjunct (Figure 5).
Statistical Analysis
One-way analysis of variance with post hoc Tukey HSD test was used to analyze differences between the treatment groups (3). There was a significant difference in reduced clotting times for Surgicel and Avitene (p<0.001, F=838.05 and Tukey HSD p<0.001).
HEALIT 3.0
The percentage volume of antibiotic powder that was dissolved into the Normal Saline solution was measured for each scenario consisting of a HEALIT covered with Tobramycin and enshrouded in the various hemostatic adjuncts (Figure 6). Only the HEALIT with Tobramycin and Surgicel was capable of dissolving all of the antibiotic powder into the Normal Saline.
DISCUSSION
Uncontrolled post-traumatic bleeding is the leading cause of potentially preventable death among injured patients. Prompt measures to minimize blood loss, restore tissue perfusion and achieve haemodynamic stability are needed to treat patients at the scene of the trauma to improve rates of survival. The time elapsed between injury and bleeding control is the most critical predictor of patient outcome (4). Tourniquet application is useful only for extremity injuries and can only be applied for a short period of time before tissue damage occurs. This includes nerve paralysis and tissue ischemia (5,6). Pressure pads are useful only for superficial injuries and cannot be easily applied continuously.
The original HEALIT was shown to significantly reduce the amount of bleeding in a traumatic wound simulator. In this present study, the further iterations of HEALIT were created. HEALIT 2.0 was designed to further promote blood clotting in the wound after the initial traumatic bleeding is slowed. HEALIT 3.0 was designed to administer a local antibiotic to also assist in preventing wound infections following the traumatic injury (Figure 7). By covering the expanding surface of the HEALIT with Surgicel, this provides a zone of enhanced coagulation between the HEALIT and the bleeding wound. The Tobramycin antibiotic powder is embedded under the Surgicel and is released during HEALIT expansion.
The Surgicel mesh expands simultaneously to allow the antibiotic powder to escape between the stretched-out latticework. The antibiotic is then spread out onto the inner surface of the wound.
CONCLUSION
HEALIT 3.0 was hypothesized to reduce the amount of bleeding from a wound, enhance coagulation to stabilize the bleeding and reduce the rate of infection. This study concludes that HEALIT 3.0 can significantly achieve all three goals in a traumatic bleeding wound simulator. As uncontrolled bleeding from trauma is the leading cause of potentially preventable death among injured patients, HEALIT 3.0 has the potential to be used in the trauma setting to improve patient survivability outcomes. HEALIT 3.0 is an inexpensive, simplistic and effective tool for paramedics and field medics to assist in the stabilization of patients with traumatic bleeding wounds. Biocompatible materials are needed to create a version of HEALIT that may be used in clinical trials. My next study will focus on testing various biocompatible expanding materials that could be inserted into the human body. Furthermore, varying sizes of the HEALIT pouches will be trialed to correspond to different wound sizes.
BIBLIOGRAPHY
1 World Health Organization. Injuries and violence: the facts; http://whqlibdoc.who.int/publications/2010/9789241599375_eng.pdf; 2010. Accessed 30 Jan 2015.
2 GBD 2013 Mortality and Causes of Death Collaborators. Global, regional, and national age–sex specific all-cause and cause-specific mortality for 240 causes of death, 1990– 2013: a systematic analysis for the Global Burden of Disease Study 2013. Lancet 2015;385(9963):117–71.
3 http://astatsa.com/OneWay_Anova_with_TukeyHSD/_result/
4 Hill D.A., West R.H., Roncal S. Outcome of patients with haemorrhagic shock: an indicator of performance in a trauma centre. J R Coll Surg Edinb. 1995;40(4):221–4.
5 Kragh Jr J.F., O’Neill M.L., Walters T.J., Jones J.A., Baer D.G., Gershman L.K., et al. “Minor morbidity with emergency tourniquet use to stop bleeding in severe limb trauma: research, history, and reconciling advocates and abolitionists”. Mil Med. 2011;176(7):817–23.
6 Dayan L., Zinmann C., Stahl S., Norman D. “Complications associated with prolonged tourniquet application on the battlefield”. Mil Med. 2008;173(1):63–6
KEANU CHAN
Keanu is attending Grade 8 at Parkland Middle School in Cranbrook, BC. He is fuelled by any variety of challenges and loves the diversity of learning. He was the BC Provincial Junior Shakespeare Speech and Dramatic Arts winner last year and has been invited to perform in professional venues. Keanu is dedicated to the Whitecaps Soccer Academy. He has a passion for surfing, kiteboarding and snowboarding. He is an avid drummer and performs with the local city orchestra. Keanu is a gifted artist and has won many awards for poetry and drawings. His inspiration comes from the people and the simple things that surround him.
