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Capstone final poster group 8

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CarmenKelly Rinard

This document describes the development of a device capable of applying a polymer blend via blow spinning laparoscopically. The current method requires open surgery. The researchers designed a 5mm diameter, 20-30cm long device that can withstand pressures of 15mmHg and successfully deliver PLGA/PEG polymer nanofibers during testing. Future work includes animal studies and a trigger mechanism to control polymer release. The global market for laparoscopic devices is growing, indicating potential for this technology.

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Laparoscopic Blow Spinning Device for Sutures Darren D’Souza, Greg Laslo, Carmen Rinard, William Swygert, Stamatia Vafeas Clinical Mentor: Dr. Anthony Sandler, Center for Surgical Care, Children’s National Medical Center Faculty Mentor: Dr. Peter Kofinas, Fischell Department of Bioengineering, University of Maryland Current methods for suturing wounds during surgery are laborious and prone to complications. Dr. Kofinas’ lab has developed a polymer solution composed of PLGA and PEG dissolved in acetone that can be applied via blow spinning to yield nanofibers. Blow spinning is done using CO2 gas which helps to create a shear force leading to the formation of nanofibers. The nanofibers have adhesive properties, and can therefore be used to complement sutures and seal internal anastomosis. In animal testing, blow spinning the polymer blend allows repaired anastomoses to withstand higher burst pressures compared to current methods. With the current device developed by researchers at Children’s National Medical Center, the polymer blend can only be applied through open surgery. There are several drawbacks to open surgery including the risk of hospital acquired bacterial infections and longer recovery times. Our objective was to develop a device capable of blow spinning this polymer laparoscopically. Motivation Approach Design Specifications ● Device must be 5mm in (outer) diameter in order to be compatible with SILS ports used during laparoscopic procedures (Figure 1) ● 20-30cm in length (typical length required for laparoscopic devices to reach the abdomen) ● Must be operable under pressures exceeding 15mmHg (the pressure that the abdomen is insufflated to during laparoscopic surgery) Figure 1. SILS port for laparoscopic surgery Our original prototype consisted of a plastic pipette tip, a 20cm plastic tube, and plastic tubing connected with electrical tape. The plastic tubing connects to the CO2 tank and the polymer was delivered via a syringe and needle to the tip of the device. Figure 4. Original prototype with enlarged depiction (Fig. 4a) of needle tip where polymer was delivered. Figure 2. Insufflated abdomen during laparoscopic procedure Device Design Results Prototype Testing After testing our device in both at atmospheric pressure and in a pressurized environment of about 8-10 mmHg (using a glove bag), we were able to successfully produce nanofibers. Testing was done using a polymer blend of 10% PLGA and 5% PEG (weight by volume) dissolved in acetone and 40 psi of CO2. The device was fit through a 5 mm trocar to ensure compatibility with laparoscopic ports. The syringe used to deliver the polymer was connected to a syringe pump, and flow rates of 50 mL/min to 125 ml/min were able to successfully yield nanofibers. Future Work Aknowledgements and References In addition to our mentors, Dr. Sandler and Dr. Kofinas, we would like to thank John Daristotle, Gary Seibel, and Justin Opfermann for their guidance and for helping to make this project possible. Eliton S., et al.“Solution Blowspinning: A New Method to Produce Micro- and Nanofibers from Polymer Solutions,” Journal of Applied Polymer Science 113 (2008): (4). Accessed December 10, 2015. doi: 10.1002/app.30275. ● Developing a spring-loaded trigger to be able to control the release of the polymer from the inner tube. ● Animal studies to further validate that our device is able to successfully deliver the polymer blend via blow spinning. Market Research Laparoscopic surgery, also known as minimally invasive surgery, is a surgical technique in which the operation is performed through small incisions. Currently, there are about 7-8 million laparoscopic surgeries performed annually throughout the world The estimated global market for laparoscopic devices is on the rise, and is expected to hit 8.5 billion dollars by 2018. Suturing wounds is a critical step to any operation and some procedures, like anastomoses, would be more efficiently completed with the development of this technology. With 40% of the surgical sealant market comprising synthetic materials a laparoscopic blow spinning device would be a welcome addition to a surgeon's tool kit. Figure 3. Blow spinning fluid model. The inner tube is where the polymer flows while the outer tube is where CO2 flows (represented by streamlines). The shear stress from the needle helps with fiber formation. Figure 5. SolidWorks sketch representing tip of our device as viewed from cross sectional view . The Inner tube delivers the polymer while the surrounding tube is filled with CO2 gas. The protrusion of the inner tube is necessary to yield proper fibers. All dimensions are in millimeters. Figure 6. Images of manufactured device, including the entire device fitted into a 5mm diameter trocar in blue (Fig 6a.), close up of the T-luer lock connector with syringe pump attached (Fig 6b.), and close up of the tip of our device (Fig 6c.). Figure 7. Fibers produced from our device on various surfaces including a petri dish (Fig 7a.) and a latex glove (Fig. 7b.). A B A CB A B Figure 8. Velocity profile of CO2 gas using COMSOL Multiphysics 4.1 software. The results demonstrate that the flow of CO2 increases within a smaller chamber to assist in fiber development. We were concerned that the sharp 90° would affect the flow rate of CO2 gas and possibly lead to turbulent flow, which may disrupt the formation of the nanofibers. Modeling of the velocity profile for the CO2 gas demonstrates that the flow remains laminar as expected.

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Capstone final poster group 8

  • 1. Laparoscopic Blow Spinning Device for Sutures Darren D’Souza, Greg Laslo, Carmen Rinard, William Swygert, Stamatia Vafeas Clinical Mentor: Dr. Anthony Sandler, Center for Surgical Care, Children’s National Medical Center Faculty Mentor: Dr. Peter Kofinas, Fischell Department of Bioengineering, University of Maryland Current methods for suturing wounds during surgery are laborious and prone to complications. Dr. Kofinas’ lab has developed a polymer solution composed of PLGA and PEG dissolved in acetone that can be applied via blow spinning to yield nanofibers. Blow spinning is done using CO2 gas which helps to create a shear force leading to the formation of nanofibers. The nanofibers have adhesive properties, and can therefore be used to complement sutures and seal internal anastomosis. In animal testing, blow spinning the polymer blend allows repaired anastomoses to withstand higher burst pressures compared to current methods. With the current device developed by researchers at Children’s National Medical Center, the polymer blend can only be applied through open surgery. There are several drawbacks to open surgery including the risk of hospital acquired bacterial infections and longer recovery times. Our objective was to develop a device capable of blow spinning this polymer laparoscopically. Motivation Approach Design Specifications ● Device must be 5mm in (outer) diameter in order to be compatible with SILS ports used during laparoscopic procedures (Figure 1) ● 20-30cm in length (typical length required for laparoscopic devices to reach the abdomen) ● Must be operable under pressures exceeding 15mmHg (the pressure that the abdomen is insufflated to during laparoscopic surgery) Figure 1. SILS port for laparoscopic surgery Our original prototype consisted of a plastic pipette tip, a 20cm plastic tube, and plastic tubing connected with electrical tape. The plastic tubing connects to the CO2 tank and the polymer was delivered via a syringe and needle to the tip of the device. Figure 4. Original prototype with enlarged depiction (Fig. 4a) of needle tip where polymer was delivered. Figure 2. Insufflated abdomen during laparoscopic procedure Device Design Results Prototype Testing After testing our device in both at atmospheric pressure and in a pressurized environment of about 8-10 mmHg (using a glove bag), we were able to successfully produce nanofibers. Testing was done using a polymer blend of 10% PLGA and 5% PEG (weight by volume) dissolved in acetone and 40 psi of CO2. The device was fit through a 5 mm trocar to ensure compatibility with laparoscopic ports. The syringe used to deliver the polymer was connected to a syringe pump, and flow rates of 50 mL/min to 125 ml/min were able to successfully yield nanofibers. Future Work Aknowledgements and References In addition to our mentors, Dr. Sandler and Dr. Kofinas, we would like to thank John Daristotle, Gary Seibel, and Justin Opfermann for their guidance and for helping to make this project possible. Eliton S., et al.“Solution Blowspinning: A New Method to Produce Micro- and Nanofibers from Polymer Solutions,” Journal of Applied Polymer Science 113 (2008): (4). Accessed December 10, 2015. doi: 10.1002/app.30275. ● Developing a spring-loaded trigger to be able to control the release of the polymer from the inner tube. ● Animal studies to further validate that our device is able to successfully deliver the polymer blend via blow spinning. Market Research Laparoscopic surgery, also known as minimally invasive surgery, is a surgical technique in which the operation is performed through small incisions. Currently, there are about 7-8 million laparoscopic surgeries performed annually throughout the world The estimated global market for laparoscopic devices is on the rise, and is expected to hit 8.5 billion dollars by 2018. Suturing wounds is a critical step to any operation and some procedures, like anastomoses, would be more efficiently completed with the development of this technology. With 40% of the surgical sealant market comprising synthetic materials a laparoscopic blow spinning device would be a welcome addition to a surgeon's tool kit. Figure 3. Blow spinning fluid model. The inner tube is where the polymer flows while the outer tube is where CO2 flows (represented by streamlines). The shear stress from the needle helps with fiber formation. Figure 5. SolidWorks sketch representing tip of our device as viewed from cross sectional view . The Inner tube delivers the polymer while the surrounding tube is filled with CO2 gas. The protrusion of the inner tube is necessary to yield proper fibers. All dimensions are in millimeters. Figure 6. Images of manufactured device, including the entire device fitted into a 5mm diameter trocar in blue (Fig 6a.), close up of the T-luer lock connector with syringe pump attached (Fig 6b.), and close up of the tip of our device (Fig 6c.). Figure 7. Fibers produced from our device on various surfaces including a petri dish (Fig 7a.) and a latex glove (Fig. 7b.). A B A CB A B Figure 8. Velocity profile of CO2 gas using COMSOL Multiphysics 4.1 software. The results demonstrate that the flow of CO2 increases within a smaller chamber to assist in fiber development. We were concerned that the sharp 90° would affect the flow rate of CO2 gas and possibly lead to turbulent flow, which may disrupt the formation of the nanofibers. Modeling of the velocity profile for the CO2 gas demonstrates that the flow remains laminar as expected.