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Onsite production of medical air: is purity a problem?
Paul Edwards1, Patricia-Ann Therriault1, Ira Katz2,3
1VitalAire Canada Inc., Mississauga, ON L5N 8R9 Canada.
Introduction:
Medical air (MA) is widely used in hospitals, often manufactured onsite by compressing external ambient air and supplied through a local network piping system. Onsite production gives rise to a risk of impurities that are governed by the same pharmacopoeia purity standards applicable to commercially produced MA. The question to be addressed in this paper is how to assess if a lack of purity poses a medical problem?
Methods:
The MA produced onsite at a major Canadian hospital was monitored for carbon dioxide (CO2) and other impurity gases at high frequency (one per minute) over a two-month period.
Results:
The average CO2 concentration was 255 ppm. The United States Pharmacopeia (USP) threshold of 500 ppm was exceeded during 1% of the total study period, and the average while exceeding the threshold was 526 ppm. The maximum concentration was 634 ppm.
Discussion And Conclusion:
To our knowledge, there is only one study that evaluated the effects suffered by respiratory patients of elevated nitric oxide in MA; thus, it is not clear what are the medical bases for the thresholds stated in the USP. To perform a Quality Risk Assessment, the threshold and the time above threshold should be considered in determining the frequency of sampling and analysis, and operating methods required to ensure the quality of MA entering the pipeline meets the clinical, regulatory, and patient safety standards. In conclusion, because the USP does not provide impurity thresholds for specific patients nor time above thresholds, there is a need for the medical community to determine these quantities before it can be known if the purity of MA is a problem.
Insights
Onsite medical air (MA) quality monitoring revealed carbon dioxide levels occasionally exceeding pharmacopoeia standards. Further medical research is needed to determine if these exceedances pose a patient safety risk.
Area of Science:
- Medical Engineering
- Pharmaceutical Science
- Respiratory Medicine
Background:
- Medical air (MA) is critical for patient care, often produced onsite in hospitals.
- Onsite MA production carries a risk of impurities, subject to pharmacopoeia purity standards.
- Assessing the clinical significance of MA impurities is essential for patient safety.
Purpose of the Study:
- To evaluate the purity of onsite-produced medical air.
- To assess the frequency and magnitude of carbon dioxide (CO2) exceedances above pharmacopoeia thresholds.
- To determine if current MA purity standards are medically justified.
Main Methods:
- High-frequency monitoring (1/min) of MA for CO2 and other impurities over two months.
- Analysis conducted at a major Canadian hospital's onsite MA production system.
- Comparison of measured CO2 levels against United States Pharmacopeia (USP) standards.
Main Results:
- Average CO2 concentration in MA was 255 ppm.
- The USP threshold of 500 ppm was exceeded during 1% of the study period.
- Peak CO2 concentration reached 634 ppm, with an average of 526 ppm during exceedance periods.
Conclusions:
- The medical basis for current USP MA impurity thresholds, like CO2, is not well-established.
- Quality Risk Assessments require consideration of both impurity levels and duration above thresholds.
- Further medical community input is needed to define patient-specific impurity limits and assess MA quality risks.
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