Monitoring Sterile Pacemaker Implants
Recommendations for performing cardiac electronic implantation emphasize strict compliance with comprehensive hygiene regulations (1). The theoretical probability of an unsterile product must not be greater than 1:1 000 000. However, how the high standards of quality and sterility of the applied products can be ensured up to the point of use remains an open question.
The components of sterile packaging have to be gas permeable in order to allow sterilants, such as superheated steam or ethylene oxide, access to the sterile products. Filter performance must compensate for airborne microbial challenge caused by air pressure and temperature variations during transport and storage. Analogous to the sterilization procedure, process evaluation for sterile product storage is necessary to provide data support for ensuring the required high level of quality.
An increase in air pressure of 15 hPa, for example, causes an air inflow of 15 mL in a 1 L packaging volume. Assuming a filtration performance of 99% and an airborne microbial load of 500 microbes per cubic meter, about 75 of 1 000 000 sterile products will be contaminated, which exceeds the sterility assurance level by 75-fold. An increase in the likelihood of non-sterility, for instance to 1:1000 in clinical epidemiological studies, would not be expected to yield significant results. However, it violates international standards and is incompatible with aseptic procedures. According to manufacturers’ instructions and some studies, filtration performance of various sterile product packagings with respect to airborne micro-organisms differs considerably (2, 3). In a study funded by seven producers, the filtration performance of the sixteen tested products was mostly between 90% and 99%, with the maximum difference factor at 50 000 (3).
With an annual 105 000 primary implantations in Germany, a postoperative infection rate of 1%, and a hospital mortality of 5% to 15%, data-based monitoring for maintaining sterility should be a priority (1).
Prof. Dr. med. Hartmut Dunkelberg
Bad Sooden-Allendorf, Germany
Conflict of interest statement
The author declares that he has a United States patent that is relevant to the topic. He has received consultant honoraria from DuPont and Kimberley & Clark as well as speaking honoraria from Kimberly & Clark.