Intravenous catheters are thin tubes which are inserted into patients' veins to administer medication or other fluids. They are commonly used in the emergency room and before surgeries. If it is impossible to use a peripheral venous catheter, a central venous catheter (CVC) may be applied. This type of catheter gets placed into the large vein in the neck, chest or groin.
Current central venous catheterisation methods need many tools and specific skills for using them appropriately. These circumstances pose a problem for the application of a CVC in pre-hospital situations.
Cevec is a product system that enables paramedics and emergency doctors to insert a central venous catheter quickly and safely. The system considers special conditions of emergency situations such as unsteady surroundings, untrained users and time pressure.
Cevec - a central venous catheter for emergencies
An iterative design process
Combining features for the new system
Step 1: Position the flexible port
Step 2: Insert the needle trough the port. The guiding sleeve will stay inside the vein.
Step 3: Advance the catheter and screw the cap onto the adapter lid
Research at the maritime rescue centre reveals an interesting topic
The project started with visits and interviews at the maritime rescue centre and the ambulance service. During an interview with an emergency doctor, I learnt that placing a catheter during emergencies can be quite challenging. In particular, the unpredictable environment and conditions may pose problems in administering medication.
How might we enable paramedics to place a central venous catheter?
Inserting a catheter into a patient's vein is a common practice to administer fluids, medicine or nutrients. Catheters are used in particular if other methods of giving medication are inapplicable. The most commonly used type of venous catheter is the peripheral venous catheter. Each year, more than 25 million patients receive peripheral catheters in the United States.
However, in some cases, a peripheral venous catheter could harm the patient: For example, if a patient suffers from hypothermia. In other cases, the medication given through a peripheral catheter might not work quickly enough.
In these cases, a central venous catheter can be used alternatively to a peripheral venous catheter. A central venous catheter (CVC) is placed into a patient's large vein. Since the body responds very fast to medication given by central venous catheters, this type of catheterisation could be a "lifesaver" during emergencies.
Still, current central venous catheterisation methods need many different tools and the skills how to use them correctly, which makes them not suitable for emergency settings.
Understanding the current standard method of placing a central venous catheter
To fully understand the process, I made research visits at the local University Hospital. There, I had the chance to observe how anaesthetists place a central venous catheter before surgeries. They have used the current standard method, called the "Seldinger technique". The on-site research proved to be very valuable for the further design explorations.
After the physician has given local anaesthesia, he or she must go through the following steps:
Steps standard technique
01 Puncture: Find the right spot to puncture. Advance the needle through the skin at approximately a 40-degree angle. As soon as blood starts to flow into the syringe, the needle has reached the vein. 02 Remove syringe: Now, remove the syringe and keep the needle in place with the non-dominant hand. 03 Advance guidewire: Insert the guidewire through the needle. 04 Pull back needle: Pull back the needle as soon as the guidewire is inserted to the appropriate length. 05 Enlarge the track: Widen the track of the insertion by advancing a dilator over the guidewire if necessary. 06 Pull back the dilator 07 Advance the catheter: Pass the catheter over the guidewire into the vessel while still holding the guidewire. 08 Pull out the guidewire: Pull back the guidewire as soon as the catheter is placed. 09 Suture: After completion, secure the catheter by suturing.
The findings define design requirements
Comparing the insights of the field research on-site with the observations made in the hospital allowed me to draw conclusions for the further design process. My main findings were the following:
01 Sterile vs unsterile environment. In the hospital, the physicians contemplate measures to work in a sterile environment. Such measures may not be taken thoroughly in the case of an emergency. The design of the equipment should take this into account. 02 Two hands-usage vs shaky and unstable environments. During my observations, I have realised that the Seldinger technique requires working with two hands at any given time during the process. However, in an emergency, especially at sea, the environment might be shaky. The paramedic might not be able to use both of his hands all the time due to these circumstances. 03 Trained vs untrained personnel. Anaesthetists are well skilled in placing catheters. Some paramedics and emergency doctors may not be equally experienced. A product for this target group should, therefore, be easy to understand. It should assist the (untrained) user in the process. Moreover, being able to pause between each step might provide paramedics assurance and confidence. 04 The number of tools. A central venous catheter kit consists of a multitude of equipment in different sizes. In an emergency, a large number of instruments may lead to confusion. There is also an increased risk of losing a piece, for example, while opening the packaging. 05 Time pressure. I have observed that preparation for and post-treatment after placing the catheter consume a lot of time. In an emergency, time is crucial. A solution should focus on being fast and immediate.
Considering these findings allowed me to set a goal for the project. My key concept became:
Design a system which enables paramedics to place a central venous catheter to administer medication during emergencies. It should be easy to understand and use. Focus on a small number of individual parts which enable a fast and secure placement.
My design process involved sketches, building and trying out different mockups and conducting feedback loops with doctors and paramedics. During the process, I realised that I needed to make the prototyping phase tangible. To explore different directions of possible solutions, I built a 1:1 foam model of a human neck. It features the correct head position for the application of a central venous catheter. The head rotates to the left, making it easy to find the anatomical landmarks for the puncture. Starting off with rather large prototypes, this foam model helped me to push my design proposal into a smaller direction. I realised that a less obtrusive design would lead to a higher acceptance.
The final design consists of only three parts: The port, the syringe and the catheter. The different parts are highly distinguishable, which prevents confusion when and how to use each instrument. The port is a supporting part which consists of an adhesive patch and a tunnel system made out of silicone. The syringe has a guiding sleeve and a two-parted adapter attached to the introducer needle. The catheter features a screwing cap. All parts work closely together and need to be put together during the catheterisation.
Redefined steps and design features
Each step can be carried out with one hand only. After each step, the doctor can pause and prepare him or herself for the next step if necessary.
01 Attach the port Before starting, clean the neck and deliver anaesthesia. Now, attach the port at the desired point of puncture. The opening at the front shows the track of the needle. The sterile and adhesive patch at the bottom of the port keeps the location underneath the part clean and prevents dirt falling in the wound.
02 Advance the needle Advance the syringe through the tunnel of the port. The port features the recommended 40° angle, which acts as a guideline for untrained paramedics. Nevertheless, it is made out of flexible silicone, which allows adjustment if necessary. An adapter tip is attached to the head of the needle. The adapter tip makes it easy to hit the chosen puncture site since it slides into the tunnel of the port. Thus, the needle will enter the skin at the desired spot, even in unsteady surroundings (for example at sea).
03 Pull back the needle Once blood enters into the syringe, the needle has approached the vein. Now it can be withdrawn. While pulling it back, the adapter tip and the adapter lid stay connected to the port. A guiding sleeve, which has covered the needle, will stay inside the vessel. It is attached to the adapter lid and consists of stretchable material.
04 Advance the catheter Advance the catheter through the stretchable guiding sleeve, which acts as a cannula. After finishing, the catheter can be connected to the adapter lid at the top of the port with a screw-cap.
To reduce the number of tools, I have combined functions of the Seldinger technique. Regarding this, the most significant difference is that Cevec uses a stretchable guiding sleeve instead of a guiding wire. An individual step to introduce this part is not required: It is inserted already into the vein by puncturing with the needle. The guidewire, the dilator and the suturing become obsolete, which reduces the number of steps and the time needed. The highly distinguishable equipment also ensures a clear understanding of the process.
Adhesive and flexible materials (for the patch, the port and the guiding sleeve) make this design proposal possible. These kinds of smart materials are now being introduced to more and more medical applications, which give a glimpse of their potential for future healthcare.
Feedback and value proposition
Cevec is a central venous catheter system which can be applied safely during emergencies. Thereby it reduces the necessary steps to a minimum and ensures a fast application. The system guides the user through the catheterisation. Between each step, the process may be interrupted, making it comfortable for untrained users.
This project gives an outline how life-saving medical processes might be altered and further developed for extreme conditions. This kind of design process may improve current standards, too: During one of my last research visits, an emergency doctor confirmed that he liked the application of sterile adhesives in this context and how the design makes suturing unnecessary.