Medical pouches can be made from various materials, including Tyvek ®, nylon or mylar-based materials, metalized films, different types of coated foils, LDPE or LLDPE and medical grade papers. Manufacturers choose which kind of material is best based on the specific barrier properties required and the type of sterilization method that will be used after the packaging process is complete.
Tyvek® and film is the most common material combination used for medical pouches. Tyvek® is made of 100% high density polyethylene fibers, and it is manufactured to be “breathable,” and yet impervious to microbes. Often, medical pouches are made from Tyvek® on one side and another material on the other side.
The characteristics of the product being packaged can impact what type of material should be used for the medical pouch. For instance, if a manufacturer is packaging bulky product that could potentially put a strain on the inside of the pouch, it may be optimal to use a pouch made from a linear low-density material that is elastic and puncture resistant. If it is human bone or tissue that needs to be packaged for transplant purposes, the medical pouch is likely to be made from Polytetrafluoroethylene (PTFE) or Teflon, materials that can withstand the cryogenic conditions required for transportation.
Medical device packaging occurs in clean rooms
Typically, medical device packaging happens in either a class 10,000 clean room (ISO class 7) or a class 100,000 clean room (ISO class 8). The numbers 10,000 and 100,000 refers to how many parts per million of particulate are allowed to be in the clean room atmosphere.
The ISO classifications for clean rooms should not be confused with the ISO designation for sterile packaging. ISO 11607 is a guidance document that is used to define many different aspects of sterile packaging. For example, for a piece of sealing equipment to be ISO 11607-compliant, it must have the ability to verify and alarm temperature, pressure, and time.
How products in medical pouches are sterilized
The products that are packaged in medical pouches are not sterilized beforehand. Instead, they are sterilized post-packaging, using either ethylene oxide (EtO) sterilization, electron beam (e-beam) sterilization, radiation sterilization or steam sterilization.
EtO sterilization is the procedure most commonly used to sterilize medical products packaged in pouches; however, it does require that at least one side of the pouch be made from a breathable material, such as Tyvek®. Generally speaking, here’s how EtO sterilization works:
After the product is sealed into a medical pouch, the pouches are packaged in boxes and cartons, palletized and sent to a sterilization facility (the entire pallet of products can be moved into a sterilization chamber all at once). Then, ethylene oxide (EtO) gas is pumped into the chamber under pressure.
In the case of a medical pouch made of Tyvek®, the EtO gas passes through the Tyvek® material, killing any contaminating microorganisms that are inside the package. Then, the pressure is relieved, as regular air is pumped back into the chamber, dispersing the EtO gas. As long as the package remains sealed and dry , the contents should remain sterile for the shelflife of the package.
Many medical products are packaged in linear, low density materials with a small Tyvek® window, or header, on one end of the pouch. These “header bags” can reduce costs, but because of the Tyvek® window, the products within them can still be sterilized using EtO sterilization.
Electron beam (e-beam) sterilization and radiation sterilization
Unlike the EtO sterilization process, electron beam (e-beam) sterilization and radiation sterilization do not require medical pouches made from breathable material. Typically, these types of sterilization processes are used for medical pouches consisting of non-breathable films or coated foils. As the names imply, e-beam sterilization uses electron beams to sterilize the medical product after packaging, and radiation sterilization uses radiation, usually in the form of high energy gamma rays.
Steam sterilization, as accomplished in an autoclave, exposes each item to direct steam contact at the required temperature and pressure for the specified time. There are four parameters of steam sterilization: steam, pressure, temperature, and time. Typically, Tyvek/film pouches are used for this application but the pouch is specifically designed to withstand the sterilization process. Typically, steam sterilizable pouches have a higher sealing temperature and a narrower processing window than pouches used for ETO sterilization.