Arterial Syringe Vent

Porex prescribes the design of a self-sealing vent for arterial syringes used in blood gas analysis. The vent provides syringe manufacturers with an added safety feature – and healthcare workers with better protection against exposure to blood and blood-born diseases.

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Design Challenge:
A need was identified in the hospital environment for better protection for healthcare workers against exposure to blood and blood born diseases during sample collection for blood gas analysis. The venting mechanism for blood collection under arterial pressures did not function well enough to assure protection. Porex working together with manufacturers of blood gas analysis equipment took on the challenge. Blood gas analysis has become a critical measurement in today’s medical profession. For patients receiving oxygen, blood samples are analyzed to ensure that proper oxygen levels are maintained. The process involves three steps: sample collection, sample storage and sample analysis. In the first step, a syringe is filled with blood under the arterial pressure of the patient. In the second step, samples must be kept in a controlled environment that prevents exposure to gases in the surrounding environment. Step three requires the delivery of the blood sample into a piece of electronic equipment for blood gas analysis.

Key requirements for the vent included a high air-flow rate at arterial pressure and assurances that the fluid (blood) entering the arterial syringe never violated or bypassed the vent. In addition, the new vent would be required to work with the components found in an existing syringe (barrel, stopple and plunger) and eliminate the possibility of the blood sample interacting with gases in the surrounding environment. Finally, Porex’s solution would have to ensure that the blood sample could be delivered to the analytical equipment via the syringe’s plunger and stopple components.

Solution:
Porex was able to impart “self-sealing” functionality, whereby the pores in the porous plastic effectively closed once placed into contact with a water-based solution. Porex material scientists worked to develop a proprietary additive that could be incorporated into the polymer blend prior to molding to yield this special feature. The incorporation of this additive into the porous plastic vent resulted in the desired objectives. The flow of blood entering the syringe from the syringe’s needle pushes air through the open pores of the porous plastic. As the syringe fills from the needle side, the fluid level approaches the stopple and vent. Once the fluid level reaches the vent, the arterial pressure from the patient's circulatory system attempts to force the blood sample into the pores of the porous plastic vent. As the blood enters the porous plastic vent, a chemical reaction takes place that increases the viscosity of the blood sample found within the pores of the porous plastic vent. Because of this localized viscosity increase, the blood in the porous plastic vent becomes unable to travel further, thereby creating a blood sample that is trapped within the matrix of the porous plastic vent. Unable to move further into the porous plastic vent, the blood effectively “seals” off the pores, preventing further blood bypass and preserving the sample in a controlled environment.

Result:
Incorporating the self-sealing vent into arterial syringes gave manufacturers a safety feature offering healthcare workers better assurance of protection against contact with blood. One of Porex’s greatest strengths lies in the diverse applications of our daily business and development opportunities. By leveraging material technology gleaned from one application into another, Porex’s development capabilities are exponentially increased. In this case, technology learned gave Porex a new functional capability to apply to other application challenges where body fluids pose a threat.

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