Frequently Asked Questions
High-Velocity Hot Air (HVHA) dry heat sterilization represents the cornerstone of CPAC’s COX RapidHeat Sterilizer technology. In order to provide a clearer understanding of the operation and performance of the COX RapidHeat Sterilizer and the HVHA sterilization technology, CPAC is providing these documented answers to frequently asked questions.
1. How do you define the term “High-Velocity Hot Air” (HVHA) technology that is employed in the COX RapidHeat Sterilizer and provide a comparison to the static dry heat sterilization process that is used in CPAC’s SteriSure and SteriDent sterilizers?
HVHA dry heat sterilization employs uniform, high velocity hot air (375° F) within the sterilization chamber that allows rapid heat transfer for maximizing microbial kill. Unlike static dry heat sterilizers which rely on gravity or low velocity fans to distribute heated air, the COX RapidHeat Sterilizer employing HVHA can sterilize instruments in minutes (6 minutes for un-wrapped instruments; 12 minutes for wrapped instruments) rather than the one to two hours that is required for static dry heat sterilization.
2. Has the HVHA sterilization process received FDA clearance as a medical product?
The FDA issued clearances for the COX RapidHeat™ Sterilizer under K872643A and K881371 in 1987 and 1988, respectively allowing a 6-minute cycle for unwrapped instruments and a 12-minute cycle for wrapped (pouched) instruments at 375° F. The unit has ETL, UL, CSA, and Health Canada approvals. CPAC Equipment, Inc., the manufacturer of the COX RapidHeat Sterilizer is an ISO 13485 certified manufacturing facility.
3. Is the COX RapidHeat Sterilizer a more complicated mechanical process than a steam sterilizer?
No, the COX RapidHeat Sterilizer involves only rapidly moving hot, dry air to sterilize instruments. As such, the only moving mechanical parts of the sterilizer are (1) the blower (fan and motor) for moving hot, dry air over a heating element, repeatedly through the sterilization chamber and (2) the cooling fan to maintain temperature control for the printed circuit board and outer sterilizer housing. There is no vacuum system nor does the unit require water or a drying system. The sterilizer is pre-set for thermocouple-controlled temperature and sterilization cycle times. The unit requires little or no maintenance as compared to the more complicated steam sterilizer technology, which requires frequent cleaning and maintenance of all the mechanisms involving the management of steam, water, pressure, and vacuum.
4. How does a COX RapidHeat Sterilizer kill microorganisms?
Contrary to steam sterilization where heat transfer is through steam contact and causes microbial death, the COX RapidHeat Sterilizer by use of heated, rapidly flowing air results in the dehydration of all forms of microorganisms, including bacterial spores. Dehydration causes the cessation of cellular metabolism as water removal from the cell increases the concentration of salts and minerals, upsetting metabolic function and resulting in microbial death.
5. Are there any other compatible HVHA technologies?
There are no other HVHA dry heat sterilizers that can deliver a consistent, uniform heating pattern throughout the sterilization chamber. The COX RapidHeat Sterilizer ensures no hot spots that may melt nylon sterilization pouches or cold areas that may influence the ability to sterilize. The inability to control temperature uniformity within other hot air convection sterilizers limits the application of the sterilizer to the sterilization of only un-wrapped instruments and may present questionable, uniform sterilization conditions.
6. What is the effectiveness of biological kill (e.g., bacterial spores) required of and achieved with the COX RapidHeat Sterilizer?
The COX RapidHeat Sterilizer has been documented via the FDA 510(k) evaluation process to deliver a 12 Log kill of Bacillus atrophaeus spores at 6 minutes and 12 minutes for sterilization cycles of un-wrapped and wrapped instruments, respectively, at 375° F.
7. How long has the HVHA sterilization technology been used in dental and healthcare practices?
The COX RapidHeat™ Transfer sterilizer has been in successful use for over 25 years in the dental and healthcare markets.
8. Can HVHA sterilization be used only on metal instruments?
Most of today’s instruments including handpieces and other instruments incorporating thermal plastic composite materials that are suitable for steam sterilization are also suitable for the higher temperatures of the COX RapidHeat Sterilizer with no negative effect on the instrument lifecycle. In recent years the creation of more heat-tolerant materials (e.g., heat-resistant fluoropolymers. silicones, and polycarbonates) and their replacement of heat-intolerant materials used in medical devices has reduced significantly the number of instruments that are intolerant to dry heat sterilization conditions.
9. Does HVHA sterilization contribute to instrument stress including corrosion and dulling of instruments?
The surgical stainless steels that are used in dental and healthcare instrumentation are also used extensively in industrial applications with operating environments in excess of 2000° F. Stainless Steel’s key attribute is the ability to maintain strength and resistance to corrosion and oxidation at these elevated temperatures. Corrosion results in micro-pitting, and dulling which directly impacts on the ability to properly sterilize therefore shortening the effective lifetime of an instrument. HVHA utilizes a fraction of the elevated temperatures used in industrial applications. Additionally, unlike steam sterilization where the corrodible elements of water are present, HVHA employs water and moisture-free sterilization where no corrosion-causing elements exist.
10. Is HVHA dry heat sterilization compatible with dental hand pieces?
The COX RapidHeat Sterilizer has been demonstrated to be compatible with dental handpieces. Non-metallic components within handpieces are constructed of high-temperature resistant materials to resist the high temperatures generated during their operation. The COX RapidHeat Sterilizer has a specific pre-set cycle (8 minutes) for the sterilization of hand pieces.
11. Can instruments be pouched or wrapped during the sterilization process to ensure their continued sterility subsequent to their removal from the COX HVHA sterilizer?
The COX HVHA sterilizer can process both wrapped and unwrapped instruments via pre-set sterilization cycles. The integrity of the nylon pouches to protect instruments after sterilization from environmental contaminants is not compromised during the sterilization process.
12. Is a drying cycle required of the COX HVHA sterilizer?
No drying cycle is required of the COX HVHA dry sterilizer since the technology relies solely on dry heat to kill microorganisms. Upon completion of the 6- minutes (unwrapped) or the 12- minute (wrapped) sterilization cycle, the instruments are retrieved from the unit and upon cooling (< than 5 minutes) are ready for use.
13. What are the times and temperatures required of the COX HVHA dry heat sterilization process?
The COX RapidHeat Sterilizer operates at 375° F and has been demonstrated to achieve a Sterility Assurance Level (SAL) of 12 Logs at 6 minutes for unwrapped instruments and at 12 minutes for wrapped instruments. The temperature and cycle times are pre-set to assure FDA compliance for time and temperature requirements.
14. What are the true times required of the total HVHA treatment cycle from start to finish?
Unlike steam sterilizers which require pre-vacuum assist and drying cycles that add to as much as 40 additional minutes to the actual three to four-minute sterilization cycle, the COX RapidHeat Sterilizer has a 12-minute cycle plus a 2-minute warm up period which brings the sterilization chamber back to temperature between cycles. Total time for completing a sterilization process from instrument loading to instrument removal is 14 to 15 minutes.
15. Can the COX RapidHeat Sterilizer replace “Immediate-Use” sterilization practices?
Since the COX RapidHeat Sterilizer’s true FDA-Cleared cycle is 6-12 minutes without the need for any drying, HVHA technology is an excellent choice to replace “Immediate-Use” steam sterilization.” COX RapidHeat Sterilizer cycles do not fall under healthcare’s definition of “immediate-use” which is a standard term used for short-cutting the drying time of steam sterilization. An “Immediate-Use” steam sterilization cycle is used by staff when an instrument or instrument set has an emergency need to be turned around as quickly as possible. If there is improper drying, subsequent cooling will cause any moisture to condense and packaged instruments to remain wet, increasing the potential for instrument corrosion. Moisture degrades the ability of the packaging to maintain sterility. Failure to dry instruments after steam sterilization violates CDC’s recommendations that state “instrument packs should be allowed to dry inside the sterilizer chamber before removing and handling. Packs should not be touched until they are cool and dry because hot packs act as wicks, absorbing moisture, and hence, bacteria from hands.”
16. Is the throughput volume of the COX RapidHeat Sterilizer equivalent to that of comparable tabletop steam sterilizers?
Although the COX RapidHeat Sterilizer has a smaller sterilization chamber, its true treatment cycle time allows four complete sterilization cycles per hour. This difference more than compensates for its smaller chamber size, resulting in a compatible or greater throughput of instruments per hour rate.
17. What is the comparative cost to operate COX RapidHeat Sterilizer?
CPAC has completed a Comparative Cost Analysis that reveals a 50% operating cost savings over a comparable steam sterilizer. Exceptional savings are found in maintenance, utility, and instrument replacement costs. Operational cost can be defined by utility costs, sterilizer–required supply costs, and equipment maintenance cost.
18. How energy efficient is the COX HVHA sterilizer as compared to comparable tabletop steam sterilizer?
The New York State Pollution Prevention Institute at The Rochester Institute of Technology performed an independent third-party energy study of the COX RapidHeat Sterilizer, providing a comparative energy analysis with two conventional tabletop steam sterilizers. As summarized in their report, the COX RapidHeat Sterilizer “sterilized small batches of instruments 3x to 6x faster using 84% less energy per cycle vs. steam sterilizers.”
19. Can the time and temperature parameters of the COX HVHA sterilization process be monitored and recorded?
The COX RapidHeat Sterilizer monitors and records for both electronic and printed storage the critical time-temperature parameters for each sterilization cycle via the use of a USB flash drive. The flash drive inserts in the sterilizer’s USB port and records cycle parameters, including start date and time, cycle phase time and temperatures (at one minute intervals), and the cycle status. The cycle status at the end of the record indicates details of the completed sterilization cycle. A typical printout will display temperature readouts between 374° F and 378° F during the sterilization cycle.
20. What are the utility requirements for COX HVHA sterilizer installation?
The COX RapidHeat Sterilizer only requires a standard 110-120V, 60Hz, 12-amp service outlet. No water, drains or other utilities are required.