Carson Pazdan Biomedical Engineer
Projects / Coursework

Hyperbaric Chamber IV Bag

A reusable, sealed bag that keeps IV pumps in a nitrogen atmosphere inside Duke's hyperbaric chambers, tested against measurable criteria through a live dive.

Context
EGR 101 Engineering Design
Role
Team member
Dates
Fall 2022
Team
5
The final bag sealed around two IV pumps inside the hyperbaric chamber
Fig. 1The final bag sealed around two IV pumps inside the hyperbaric chamber.

Problem. Duke's hyperbaric chambers run at high pressure with a high concentration of oxygen. Our clients told us a single electrical spark in that environment could cause an explosion severe enough to level the building. To keep the IV pumps inside surrounded by nitrogen, nurses were covering them with a trash bag clipped to the IV pole with a binder clip. It was slow to set up, and nitrogen leaked out through tears.

Design criteria. We defined measurable targets with our clients before designing:

Criterion Target
Safety Meets NFPA 701 and NFPA 99 guidelines
Size Encloses 2 IV pump units and 8 IV bags, plus power, sample, and feed lines
Transparency >90% light transmission
Durability No tearing within 3 months; seams withstand 20 lb of force
Ease of use Attach or detach in under 30 seconds
Airtightness Releases no more than 2% of nitrogen pumped at 5–10 L/min
Reusability Survives hospital disinfection for 3 months
Usability Every pump button can be pressed through the material

Design. 20-gauge clear vinyl gives the bag its shape and lets nurses see and press the pump screens. A 40-inch waterproof TPU zipper, sewn in and sealed with Flex Paste, opens it, and sealant tape and thread close the seams. A 3D-printed clamp with slots for the nitrogen line and power cords attaches the bag to the IV pole without pinching anything. It replaced an earlier silicone "head tent" seal that didn't work.

Testing

An early prototype failing its water-leak test (left), water-testing the seal at the IV pole clamp (center), and suited up for the test dive in Duke's hyperbaric chamber (right)An early prototype failing its water-leak test (left), water-testing the seal at the IV pole clamp (center), and suited up for the test dive in Duke's hyperbaric chamber (right)An early prototype failing its water-leak test (left), water-testing the seal at the IV pole clamp (center), and suited up for the test dive in Duke's hyperbaric chamber (right)
Fig. 2An early prototype failing its water-leak test (left), water-testing the seal at the IV pole clamp (center), and suited up for the test dive in Duke's hyperbaric chamber (right).
Criterion Method Result
Durability Spring scale on seams, zipper, and vinyl Withstood 20 lb. PASS
Airtightness Water fill, spot-check seams <5% leakage at seams. PASS
Airtightness Nitrogen fill during a chamber dive ≥99.5% nitrogen retained through a dive. PASS
Reusability Hospital disinfectant on every material 0% degradation. PASS
Usability Each pump button pressed 20x through vinyl 100% pressable. PASS
Ease of use User rating of the zipper All users rated ≥4. PASS

Outcome. We presented at the EGR 101 poster session, where nurses from the hyperbaric unit called it a clear improvement over the trash-bag method.

The final bag and our poster at the design showcase
Fig. 3The final bag and our poster at the design showcase.
Our team in the hyperbaric chamber
Fig. 4Our team in the hyperbaric chamber.

What I learned. Our early prototypes failed leak testing over and over, and it wore on the team. What got us through was treating each failure as data about where the seal broke, not as a verdict on the design, and combining the best parts of everyone's ideas into the final version. It was my first design project, and it's where I learned that a good test tells you exactly what to fix next.

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