P10023 Detailed Design Review Presentation Document
P10023
Ventricular Assist Device Implantation Simulator
Detailed Design Review
November 6, 2009
Table of Contents – Detailed Design Review
Design Review Agenda
Meeting Timeline:
Project Description
Project Background:
Objectives/Scope:
Core Team Members:
Customer Needs
Engineering Specifications
Selected Concepts and Design
Heart and Fluid System:
Selection Process:
Needs and Specifications Addressed:
Frame and Ribs:
Selection Process:
Needs and Specifications Addressed:
Lungs and Diaphragm:
Selection Process:
Needs and Specifications Addressed:
Risks and Mitigation
Bill of Materials
Budget
Project # / Project Name / Project Track / Project FamilyP10023 / VAD Implantation Simulator / Assistive Devices and Bioengineering / Biomedical Device Development
Start Term / Team Guide / Project Sponsor / Doc. Revision
091 / Dr Steven Day / A
Design Review Agenda
Meeting Purpose:
The purpose of this meeting is to present and review a detailed design, including a bill of materials and budget, of our VAD implantation device and to receive feedback on all aspects.
Meeting Date: November 6, 2009
Meeting Time: 1:00pm – 3:00pm
Meeting Location: Building 09 Room 4435
Meeting Timeline:
Start Time: / Topic of Review / Required Attendees1:00 PM / Project Background Recap
1:10 PM / Selected Concept and Design
1:30 PM / Heart and Fluid System Selection and Feasability
2:00 PM / Frame and Ribs Selection and Feasability
2:30 PM / Bill of Materials, Risk Assessment, and Budget
2:50 PM / Wrap up and Discussion
Project Description
Project Background:
As ventricular assist devices grow in popularity, the training of surgeons for this relatively new procedure is becoming important. The surgical implantation of a left ventricular assist device requires, among other things, the cannulation (cutting a hole) in the left ventricle for connection of the inlet tube of the pump, and proper placement of this cannula within the ventricle. The current practice for training for the implantation of an LVAD is to perform this cannulation on non-pressurized pig hearts sitting in a metal tray and then on a very limited number of live animals. The flaccid nature of the heart is not realistic. Our collaborators at Strong regularly run sessions to train residents and surgeons on this procedure and have been developing more realistic simulators of this procedure. The proposed MSD project would be to create a device that houses a pig heart in an environment that presents the practicing surgeon with something a little more realistic than an open tin, possibly including features such as: use of rib spreaders that limit access to the site, a simulated diaphragm to further simulate the confined space they have to work with, a fake "sternum" that could be cut with a saw, controlled pressure applied to the pig heart and possibility of a "beating" heart.
Mission Statement:
The mission of project P10023 is to develop a training simulator for surgeons to use for implantation of an LVAD (Left Ventricular Assist Device). The simulator is to have the look of an average human torso, with as many realistic anatomical details possible (i.e. beating heart, moving diaphragm, ribs, etc.). This is to be accomplished by the end of winter quarter (092)
Objectives/Scope:
Our business goals, summed by our mission statement, are to have a Generation I 1:1 replica of a human torso that simulates the human body and functions during surgery for training of surgeons.
Value of Project:
The VAD implantation simulator will have much value to the medical community, whether it is for med students or trained professionals learning a new procedure. The device will provide a realistic environment for surgeons to work with before they move on to train on animals. With the procedure becoming more and more common, well trained surgeons are desired in the industry.
Core Team Members:
- Dennis Prentice:ME, Project Manager, Frame/stand subsystem
- Belinda Segui: EE, Heart subsystem
- Anthony Culotta: ME, Fake Organs
- Jason Nichols: ME, Storage unit for organs (workspace)
P10023 Detailed Design Review Presentation Document
Customer Needs
Engineering Specifications
Revision #: 4Engr. Spec. # / Importance / Source / Specification (description) / Unit of Measure / Marginal Value / Ideal Value / Comments/Status
ES1 / 1 / CN1, CN15, CN17 / Heart Pressurized / mm Hg / +/- 10 / 80 / blood pressure at rest
ES2 / 1 / CN2, CN15 / Realistic Orientation of Heart / degrees / +/- 5 / 75 / aorta/left ventrical relative to head of torso (which is considered 90 degrees)
ES2.1 / 1 / CN2, CN15 / Position in Relation to Other Organs / yes/no / N/A / yes / is it near the organs it should be? - yes is achieved by inspection
ES3 / 1 / CN3, CN26 / Surgical Field / cm x cm / +/- 2.54 / 22.86 x 25.4 / in relation to surgeon visibility
ES3.1 / 1 / CN3,CN4, CN15, CN26 / Confined workspace / cm x cm / +/- 2.54 / 22.86 x 25.4
ES4 / 1 / CN5, CN7, CN14 / Feature: Cow Heart / yes/no / N/A / yes / surgeons purchase hearts independently
ES5 / 1 / CN6, CN13, CN18 / Feature: Cleanable Materials Used / yes/no / N/A / yes / can it be cleaned with cleaning supplies?
ES6 / 2 / CN13 / Quick setup / minutes / +/-15 / 30 / prep for the trainer to be used once
ES6.1 / 2 / CN13 / Between uses prep time / minutes / +/-5 / 16 / prep per heart
ES6.2 / 2 / CN13 / Quick teardown / minutes
ES6.3 / 2 / CN13 / One power cord / quantity of power cords / -1 / 1
ES6.4 / 2 / CN13 / One Power Switch / quantity of switches / -1 / 1
ES7 / 4 / CN6,CN13, CN18 / Maintenance / Wipe down parts that touch the heart between use.
ES7.1 / 4 / CN6, CN13, CN18 / Featured for Contained Mess - Single Drain Point / yes/no / N/A / yes
ES8 / 1 / CN8 / Feature: Replaceable Connected Tubing to Heart / yes/no / N/A / yes / Yes is achieved when tubing is made out of parts that a surgeon can easily purchase and therefore replace.
ES8.1 / 1 / CN8, CN15 / Size of Aorta / cm / -1 / 2.54
ES9 / 2 / CN9 / Ease of Transport
ES9.1 / 2 / CN9, CN12 / Weight / kg / Fits on Standard Cart
ES9.2 / 2 / CN9, CN12 / Trainer Dimensions / cm x cm x cm / +/- 2 cm x cm x cm / 15.24 x 15.24 x 25.4
ES10 / 2 / CN10 / Ease of Storage
Feature: Has a cover / yes/no / N/A / yes / to avoid dust
ES11 / 2 / CN11, CN22 / 3-4 times/month / yes/no / N/A / yes / Yes is achieved if the trainer survives standard usage for given amount of time without breaking or only requiring standard tools to fix (no special tools).
ES12 / 2 / CN14, CN16, CN20, CN21, CN25, CN28, CN29 / Replaceable NonHeart Organs made of inexpensive materials / $ / +/-25 / 50 / Plasticize
ES13 / 2 / CN15 / Match Average Patient / Average Male
ES13.1 / 2 / CN15, CN17 / Heart Beat Rate / beats/minute / +10 / -0 / 40
ES13.2 / 2 / CN12, CN15, CN24 / Thoracic Cavity Volume / cm3 / 4060.1 / value without lungs
Es13.3 / 7 / CN12, CN15, CN24 / Body Surface Area / m2 / +/- 0.15 / 2
ES14 / 3 / CN14, CN15, CN16, CN28 / Feature: Incorporation of lungs (fake - polymer/elastomer) / yes/no / N/A / yes
ES15 / 5 / CN15, CN17, CN19, CN23, CN30 / Blood flow / ml/heart beat / +/- 10 ml / 70 / LVAD Is Allowed to Pump After Implantation (this currently isn't mandatory). If this is achieved, mistakes can be detected when pump doesn't work properly
ES15.1 / 5 / CN15, CN17, CN19, CN23, CN30 / Amount of blood / Liters / +/- 0.4 / 5.6 / average person
ES16 / 5 / CN22 / Trainer Life / years / +/- 2 / 7
ES17 / 8 / CN4, CN26 / Rib Spreading Length / cm / +/- 1 / 22.86
Engr. Spec. #: enables cross-referencing (traceability) and allows mapping to lower level specs within separate documents
Source: Customer need #, regulatory standard (eg. EN 60601), and/or "implied" (must exist but doesn't have an associated customer need)
Description: quantitative, measureable, testable details
*This table can be expanded to document test results
This represents the general spec title
This represents that further research is required
P10023 Detailed Design Review Presentation Document
Selected Concepts and Design
Heart and Fluid System:
Selection Process:
Belinda, if you could update the stuff you have here.
Needs and Specifications Addressed:
Frame and Ribs:
Selection Process:
The selection process of the frame and ribs was not as involved as the fluid systems since there was already a phase I benchmark idea. Initially, many ideas were brought up for materials, connections for the ribs, as well as incorporation of many features. The first step in the process was benchmarking. Many ideas were taken from each benchmarked idea in order to use the pros of each and in an attempt to eliminate the cons of each.
The concept that resulted from the process can be seen fully developed in Figure XX.
The idea behind the concept is to have the convex ribs covered by a rubber-silicone material to make the torso more realistic. Under the silicone rubber is a set of ten aluminum ribs that are spreadable by use of a typical rib spreader, as can be seen in Figure XX. The hinges allow movement of the ribs, but limit them at the upright position. The ribs are held in the upright natural position by two springs. These springs are removable so that the tray holding the heart can be removed and cleaned externally. South of the main rib section is a set of three angled ribs representing the abs region just below the thoracic cavity. In this space is a walled pocket for installation of the VAD as seen in Figure XX. The tray that the heart sits in, which is the rest of the tray seen in Figure XX, sits on a base made of four base pieces, as seen in Figure’s XX and XX. One set of the base pieces have cuts into them to allow the feet of the tray to sit in securely. All aluminum parts are going to be welded together.
INPUT FIGURE XX HERE (WHOLE FRAME)
Figure XX shows the entire frame with ribs and the organ tray. The five straight ribs on each side are on hinges, with springs attached to the first and last rib.
INPUT FIGURE XX HERE (BASE PART 1)
INPUT FIGURE XX HERE (BASE PART 2)
INPUT FIGURE XX HERE (RIB)
INPUT FIGURE XX HERE (STERNUM)
INPUT FIGURE XX HERE (TRAY)
Figure’s 2 – 6 show each part and their dimensions. These are an attempt to make the replica as close to a 1:1 model as possible to an average
Needs and Specifications Addressed:
Trainer Dimensions and Thoracic Cavity Volume:Only incorporates necessary parts, and is accurate size compared to an average adult male torso.
Rib Spreading Length:Using the same springs employed currently, or ones with similar spring rates, and with the hinges, the ribs will spread the necessary ~9in.
Light Weight and Durable: Using Aluminum as the main building material, the product will be durable and light weight.
Surgical Field and Confined Workspace: The surgical field is the area in which the procedure is completed, which is a 7” x 9” area in the chest. The ribs will be covered with a “skin” so that the field of view is reduced.
Cleanable: Putting screws in the aluminum for the springs to attach to allow the springs to be disconnected. If they are disconnected, the ribs only need to be hinged open in order to clean. This also allows the tray for the heart and lungs to be removed to be cleaned externally.
Lungs and Diaphragm:
Selection Process:
Many different concepts were discussed when attempting to address the lung and diaphragm organs to be incorporated into the design project. At first, some benchmarking took place to see which kinds of existing models there were and if they met the needs and specifications of our group. Many websites existed, offering intricate and detailed replicas of any organ imaginable. Because of the high level of machining and resources used to make most of these professional models, the prices were much higher than the value they would serve for our project. The selection process emphasized a search for materials in a final design that would be flexible, cleanable, and reusable. A meeting with graduate student Emily Berg proved to be a great help, as she had much experience in modeling, molding, and casting lungs. After a discussion with her, a consensus was made that the best plan of action would be to use DOW CORNING 3110 Silicone Rubber with a 1 Catalyst to cover a paper meche mold of the outer outline of a human lung. The diaphragm was specified by the customer as a low priority feature to the LVAD simulator. The diaphragm’s role in the surgery is to, in essence, do nothing more than be moved aside so that the LVAD pump can sit comfortable between it, and the abdominal muscle. Hence, for the diaphragm too, it was important to decide on a thin, flexible material that could be easily manipulated or moved out of the way, to implant the LVAD. Taking these needs into consideration, parafilm was decided on as the best substance, as it is a stretchable, moldable, waterproof, self-adhering substance.
Needs and Specifications Addressed:
Flexible: As is the case with all elastomers, 3110 Silicone Rubber is very flexible, imitating the durability of real human lungs. Because of the close proximity of the heart to the lungs in both real life, and in our team setup, the flexibility of the lungs is important as they will have some ‘give’ to them when the surgeons push against them while dealing with the heart.
Cleanability: As there are going to be real calf hearts in the simulator, it is inevitable that blood will be touching several parts of the setup. Following health and safety standards, it was an important need to make sure that whichever substance was chosen to make the lungs and diaphragm out of, it would need to be easily cleanable. Initial considerations such as clay and plastic were not the best choices in terms of easy clean-up, as they were susceptible to possible permanent staining. Silicone rubber is a solid, yet flexible material that is very durable, and can easy by rinsed off with soap and water when come into contact with a bio-hazard.
Reusability: Another important need of the customer was the need for the setup to be reusable. As of now, the most efficient way that surgeons train for the LVAD surgery is for several of them to gather around a living calf, and take turns performing different steps of the surgery on a live animal. This is neither a convenient, nor efficient way for practice. Making the lungs, diaphragm, and all other parts of the setup reusable is a must, as it enables the setups to be cleaned quickly, and prepared right away for another surgeon to practice. The future prospect of producing multiple simulators is also enticing, as several surgeons can perform the surgery multiple times at clinics or demonstrations.
P10023 Detailed Design Review Presentation Document
Risks and Mitigation
MSD Project Risk Assessment Template
ID / Risk Item / Effect / Cause / Likelihood / Severity / Importance / Action to Minimize Risk / Owner1 / Unable to keep the heart properly pressurized / Non-realistic simulation / Improperly researched pumps / 1 / 3 / 3 / Better research pumps
Better research pressure in heart / Belinda
2 / Unable to make accurate heart beat / Non-realistic simulation
Useless to Surgeons / Improperly programmed microcontrollers/pumps / 1 / 3 / 3 / Better research controllers
Better research pumps / Belinda
3 / Inaccurate replication of organs / Not as valuable to surgeons / Inaccurate material research / 2 / 1 / 2 / Research materials
Talk to customer in regards to organ texture, etc. / Anthony
4 / Brainstormed ideas end up out of monetary scope of project / Project undevelopable / Poor budgeting / 2 / 3 / 6 / Cost analysis
Budget
Allocate funds / Team
5 / Replicated organs wear out / Shortened life of simulator / Poor material research / 1 / 2 / 2 / Better material research / Anthony
6 / Lack of cohesiveness between group members / Project doesn’t mesh together / Lack of communication / 1 / 3 / 3 / Update teammates constantly
Follow team values and norms / Team
7 / Ability to finish by week 11 / Not everything can be included in project / Improper time management
Lack of customer input in beginning of quarter pushed project back / 2 / 1 / 2 / Change scope of project to ease time management, and better likelihood of finishing project / Dennis
Team
8 / Lack of customer input / Poor needs assessment / Busy customer schedule / 3 / 3 / 9 / Use secondary customer as much as possible
Be as detailed as possible in customer interactions / Team
10 / Delay in shipments of hearts / Delays preliminary tests to help select quick connects for heart/“arteries” / Orders sent out week 7 or later / 2 / 1 / 2 / As soon as information given by Dr Day, order a few hearts / Dennis
Belinda
11 / Lack of Funding / No project (never leaves concept phase) / Did not acquire funds / 2 / 3 / 6 / Ask customers for funding, Dr Day / Team
ID / Risk Item / Effect / Cause / Likelihood / Severity / Importance / Action to Minimize Risk / Owner
12 / Deteriorated Heart / Poor simulation / Acquisition of poor cow hearts / 2 / 1 / 2 / Inspect hearts upon acquisition
Gage pressure through heart / Dennis
Belinda
13 / Long lead times in material orders / Delay in phase II / Did not order in a timely manner / 2 / 3 / 6 / Order as soon as design is approved to prevent delays / Dennis
Anthony
14 / Long line for machining / Delay in building phase / Other groups getting machining forms in before us / 2 / 2 / 4 / As soon as material arrives, deliver machining request / Dennis
Anthony
Jason
15 / Fluid system doesn’t work to specification / No beating heart, fluid doesn’t flow properly / Design Flaw: Controller selected incorrect for system, Valves don’t work as expected / 2 / 3 / 6 / Re-evaluate all Fluid system specs and design concepts / Dennis
Belinda
Jason
16 / Lack of materials / Longer lead time / Out of stock at primary merchant researched / 2 / 2 / 4 / Find secondary vendors for all products / Team
17 / Lungs not realistic / Improper representation of lungs / Material not properly molded / 2 / 2 / 4 / Research dimensions of lungs, molding ideas / Jason
Anthony
Likelihood scale / Severity scale
1 - This cause is unlikely to happen / 1 - The impact on the project is very minor. We will still meet deliverables on time and within budget, but it will cause extra work
2 - This cause could conceivably happen / 2 - The impact on the project is noticeable. We will deliver reduced functionality, go over budget, or fail to meet some of our Engineering Specifications.
3 - This cause is very likely to happen / 3 - The impact on the project is severe. We will not be able to deliver, or what we deliver will not meet the customer's needs.
Bill of Materials
Budget
Derived from Bill of Materials