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HUMAN BODY FLUIDS
Body fluids constitute 55-60% of the total body mass depending on gender, and consists of 2/3 intracellular fluid, fluid within the cells and 1/3 extracellular fluid, the fluid outside the cells . The extracellular fluid is divided into extravascular compartment, the space between the cells but not within the blood vessels that contains the interstitial fluid, and the intravascular compartment, the space within the blood vessels containing blood plasma. Water makes up for 45-75% of the total body mass and is the largest component of the body. The required amount of water and solutes must be present and correctly proportioned for the body to be in fluid balance.
Blood is a liquid tissue consisting of cells surrounded by a liquid extracellular matrix, called blood plasma. The blood has two main components, blood plasma and formed elements. The formed elements include three types of blood cells, erythrocytes, leukocytes and thrombocytes, with different structure and functions. The specific functions of blood include transportation of nutrients from the gastrointestinal tract and oxygen from the lungs. These products diffuse from the blood into the interstitial fluid and then into the body cells. The reverse direction is used when carbon dioxide and wastes from the cells are removed and transported to various organs e.g. the lungs and kidneys for elimination from the body. The blood also helps regulate the pH and adjust the body temperature. The leukocytes and different types of blood proteins help protect the body against disease in various ways. The blood can also clot to prevent massive blood loss after an injury.
Hypovolemic shock is a decrease of intravascular (IV) volume resulting from e.g. internal and external hemorrhage, dehydration or a decrease of vascular permeability. Hypovolemic shock causes inadequate tissue perfusion and precipitation of cellular ischemia. Cardiac reserve and the rate of volume loss are two consequential factors in the development of hypovolemic shock and each stage of the development involves different physical compensatory responses. Clinical indicators of hypovolemic shock include e.g. low blood pressure, pale skin, elevated heart rate, altering mental status and decreased urine output . Volume replacement is crucial and substantial procedure for resuscitation from hypovolemic shock. A blood volume loss of more than 40% is immediately life-threatening and within 15 minutes the mortality is 50% [7, 8]. Consequently, a fast and aggressive treatment is required during hypovolemic shock.
The fluids transfused are blood products, crystalloids and/or colloids. The most optimal choice of resuscitation fluid is an ongoing debate and research topic . All IV fluids rapidly infused are warmed, to prevent and contain hypothermia. The allogeneic blood products transfused include erythrocytes and plasma.
Crystalloids effect fluid resuscitation by expanding the interstitial volume. Normal saline is the most commonly used crystalloid fluid and is a solution of isotonic sodium chloride at 0.9% concentration. Ringer’s acetate is another regularly used isotonic crystalloid solution. Colloids are large molecules and the principal benefit of colloids is effective resuscitation of plasma volume. An example of a colloid resuscitation fluid is volulyte. The dimension of the IV bag varies depending on fluid and volume.
Administrating fluids to the patient by gravity infusion systems is insufficient when the rate of volume loss exceeds the rate of restoration. Rapid infusion systems are used as a standardized procedure today to achieve rapid fluid resuscitation during hypovolemic shock.
Hand-inflated infusion cuffs represent the same concept as a blood pressure cuff and are ideal for ambulances due to their mobility. The IV bag is placed inside the cuff and inflated manually with a hand pump and pressure is applied to the fluid bag. Hand-inflated infusion cuffs are easy to use but have presented difficulties in maintaining a constant pressure, thus require constant pressure monitoring .
The rapid infusion system generates significantly higher flow rates than hand-inflated infusion cuffs. These devices allow infusion of fluid and blood products at precise rates and have shown ease, rapidity, precision and effectiveness in the resuscitation process for patients requiring massive transfusion . There are two leading types of systems; one is driven by a compressor while the other needs to be connected to the hospital wall pressurized gas outlets. Although these devices have different pressurized air sources, their overall concept is similar. The system is mounted on an IV pole and includes one or two pressure chambers, a sealed fluid heater device, in some constructions an air detector device and interconnecting tubes. The fluid bags are spiked and placed in the chambers. The IV tubing must be adequately primed in order to remove all air bubbles. Once the system is turned on the internal inflation in the chamber grows, applying pressure to the fluid bag. If a double chamber system is used, one bag can be operating while the next bag is prepared in the other chamber.
Rapid infusers systems are used during surgical procedures in the anesthesia and intensive care unit, ER, obstetrics and gynecology and the urology division. At the anesthesia and intensive care unit critically ill or injured patients are treated and surgical procedures are performed. They are responsible for anesthesia, intensive care and pain management in surgical interventions and implement both planned and emergency procedures. In anesthesia and intensive care major hemorrhage is a common and critical condition and can occur peri- and postoperative. Perioperative severe hemorrhage is a critical and life-threatening impediment for the patient and correspondingly complicates the surgical procedure, thus further increasing mortality rates . The department of obstetrics and gynecology include surgical procedures like cesarean section, laparoscopy, hysterectomy and abortion. Postpartum hemorrhage is the worldwide leading cause of maternal mortality and is often unexpected and sudden . Uterine atony and placenta accreta are examples of common causes of postpartum hemorrhage.
Rapid infusers are used in urology for ureteroscopy and cystoscopy examinations. The field of application at the urology department differs from the other departments. Lower pressures are used and one clear solution fluid bag is often enough for a procedure. Pressurized saline is used as a standard solution for irrigation and to expand e.g. the urethra and the bladder to improve visualization and also for e.g. removing blood, tissue or stone fragments.
The fluid administration is performed by the the nurse anesthetist. Rapid fluid administration includes i.e. monitoring parameters, operating and managing the infusion device and regulating the administration rate. During excessive hemorrhage, rapid blood transfusion is a demanding and time-consuming duty and one nurse must completely engage in this task. Generally a rapid fluid infuser set is always available in an OR. When the risk for blood loss appears imminent, availability of a rapid fluid infuser is obligated.
QUALITY FUNCTION DEPLOYMENT
An essential and often problematic part of the design process is to understand and define the customers’ problems and needs. There are many developed methods today for the generation of customer specifications, and one of them is called Quality Function Deployment (QFD) . QFD is an efficient customer requirement development tool and is based on identifying the customer and ensuring that the engineering team has thoroughly understood the problems. It translates the requirements into measurable parameters and includes an evaluation of the competition. This method was developed in the mid-1970s in Japan and the Japanese automotive manufacturer Toyota improved the quality of their new car model while reducing their development time by one third and their development costs by 60% by using this method. 
The QFD method includes eight steps, as follows:
1) Identify the customers.
2) Determine the customers’ requirements.
3) Determine relative importance of the requirements.
4) Identify and evaluate the competition.
5) Generate engineering specifications.
6) Set up technical targets for the product.
7) Set engineering specification targets and importance.
8) Identify relationships between engineering specification.
During the implementation of each step, a matrix called the house of quality (figure 2) is successively filled out. The numbers in each “room” of the house of quality refers to the eight steps and are specified below.
In the beginning of a project many ideas should be explored and considered, thus, brainstorming is a good method . The aim of the method is to produce a large number of ideas and suggestions. Brainstorming may be the most creative and open-ended activity of the project. It is important to be open-minded and receptive to all sorts of ideas. This task can be useful for people working in a group but also for individual projects.
Creating a product that meets the demands, is innovative and can differentiate itself on the market, requires a good and efficient concept generation. There are four factors that are applicable for the concept generation process :
1. Criticism and judgment should be suspended during concept generation. Judgmental thinking should be converted into suggestions for alternative concepts.
2. Generation of a large number of ideas increases the likelihood of completely exploring the solution space. Each idea has shown to act as a stimulus for other ideas, so a large number of ideas further stimulate the generation of even more ideas.
3. Ideas that may seem infeasible are actually valuable and should be welcomed. Infeasible ideas can often be improved and most importantly they stretch the boundaries of the solution space and encourage the group to think in a new way.
4. Abundant sketching surfaces should be provided since text and verbal language may be an inefficient and difficult tool when reasoning ideas.
Brainstorming sessions were carried out individually but also with students and peers in the same field of study. Discussions concerning various ideas also took place with the external supervisor. In the initial phase brainstorming sessions were conducted to explore general solutions and ideas. Further on, the idea generation sessions were focused on specific features and detailed solutions. Specifications that acquired high ratings in the QFD matrix received extra focus during these sessions. The QFD also raised awareness regarding existing solutions and these were considered during the idea generation.
During this phase the market was also explored for components and solutions that could be needed and implemented in the new design. E.g. accessibility, alternatives and cost were considered during the search and generation of a plausible solution.
COMPUTER AIDED DESIGN
The choice of concept and design solutions was made in agreement with the supervisors. Initially several hand sketches were made to examine and analyze different design solutions. To design the prototype, the 3D CAD program for mechanical constructions, SolidWorks (Dassault Systemes, Velizy, France) was used. Within this program a 3D prototype and technical drawings were created. Measurements of fluid bags at the Stockholm South General Hospital lead to dimensioning of the chambers.
The users and the situations in which the device is going to be used were constantly considered when developing the control panel. Also here, several hand sketches were made in forehand to examine and analyze different designs. Clear explanations and markings were considered in order to avoid misunderstandings and errors during handling.
Table of contents :
TABLE OF CONTENTS
1.1 SLL INNOVATION
1.2 PROBLEM DEFINITION
4.1 HUMAN BODY FLUIDS
4.2 FLUID RESUSCITATION
4.3 RAPID INFUSERS
4.4 PRODUCT DEVELOPMENT
4.4.1 QUALITY FUNCTION DEPLOYMENT
4.4.2 IDEA GENERATION
5.1 QUALITY FUNCTION DEPLOYMENT
5.2.1 IDEA GENERATION
5.2.2 COMPUTER AIDED DESIGN
6.1 QUALITY FUNCTION DEPLOYMENT
6.2.1 COMPUTER AIDED DESIGN
6.2.2 DESIGN SPECIFICATIONS
7.1 RESEARCH LIMITATIONS
7.2 FUTURE WORK