Frequently Asked Questions
High-Velocity Hot Air (HVHA) dry heat sterilization represents the cornerstone of CPAC Equipment’s RapidHeat™ Sterilizer technology. In order to provide a clearer understanding of the operation and performance of RapidHeat sterilizers 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 RapidHeat sterilizers 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, RapidHeat sterilizers employ HVHA that can sterilize instruments in minutes rather than hours required for static dry heat sterilization.
2. Has the HVHA sterilization process received FDA clearance as a medical product?
The FDA issued clearances for our RapidHeat sterilizers under K872643A and K881371 in 1987 and 1988, respectively. These units have ETL, UL, and applicable CE approvals. CPAC Equipment, Inc., the manufacturer of RapidHeat sterilizers, is an ISO 13485 certified manufacturing facility.
3. Is the RapidHeat Sterilizer a more complicated mechanical process than a steam sterilizer?
No, the 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 boards 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 RapidHeat Sterilizer kill microorganisms?
Bacterial spore inactivation by dry heat occurs primarily from DNA damage, unlike wet heat, which kills spores by a combination of other mechanisms. Examination of the mutational events that occur after dry heat exposure has shown that spore DNA has been physically damaged by single-stranded breaks. Further examination has suggested that the process of depurination is the major mechanism by which dry heat causes damage in bacterial spores. The thermal-chemical reaction of deoxyadenosine and deoxyguanosine results in the cleavage of β-N-glycosidic bonds that release adenine or guanine leading directly to single-stranded DNA breaks. Research data suggests that protective small, acid-soluble spore proteins are less effective at the higher dry heat temperatures, causing depurination and ultimately DNA strand cleavage which can lead to lethal mutational events and cellular 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. . Other hot air convection sterilizers don’t have the ability to control chamber temperature therefor limiting the application of the sterilizer to the sterilization of only un-wrapped instruments which would also present questionable, uniform sterilization conditions.
6. What is the effectiveness of biological kill (e.g., bacterial spores) required of and achieved with the RapidHeat Sterilizer?
RapidHeat sterilizers have been documented via the FDA 510(k) evaluation process to deliver a 12 Log kill of Bacillus atrophaeus spores for all sterilization cycles of un-wrapped, wrapped instruments, and handpieces. Once instruments have reached the spore kill initiation temperature, the bacterial spore kill rate is 1 Log per 32 seconds for both wrapped and unwrapped instruments. Extrapolation of that rate results in obtaining a 12 Log kill in approximately six minutes from initiation of spore kill.
7. How long has the HVHA sterilization technology been used in dental and healthcare practices?
RapidHeat sterilizers have 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 RapidHeat sterilizers 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 impact on the ability to properly sterilize and shortens the effective lifetime of an instrument, respectively. HVHA operates at a fraction of the temperatures used in industrial applications. Additionally, unlike steam sterilization where the corrodible elements of water are present, HVHA employs water-free and moisture-free sterilization where no corrosion-causing elements exist.
10. Is HVHA dry heat sterilization compatible with dental hand pieces?
RapidHeat sterilizers have 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. Handpiece organic (mineral oil based) lubricants are required to be replaced by a high-temperature synthetic (food-grade) lubricant, such as Super Lube. RapidHeat sterilizers have a specific pre-set cycle 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 HVHA sterilizer?
The 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 HVHA sterilizer?
No drying cycle is required of the HVHA dry sterilizer since the technology relies solely on dry heat to kill microorganisms. Upon completion of the selected sterilization cycle, the instruments are retrieved from the unit and upon cooling approximately 5 to 7 minutes) are ready for use.
13. What are the times and temperatures required of the HVHA dry heat sterilization process?
RapidHeat sterilizers operate at 375° F and have been demonstrated to achieve a Sterility Assurance Level (SAL) of 12 Logs for all sterilization cycles. The temperature and cycle times are pre-set to assure FDA compliance for time and temperature requirements based on load size, configuration, and packaging specifications. Shortest cycle time is 6 minutes for unwrapped instruments (Cox RapidHeat Sterilizer) to 21 minutes for a full capacity load of wrapped instruments (3.2 kg instruments) in the RH-Pro11 sterilizer.
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, RapidHeat sterilizers have pre-set sterilization cycles ranging from six minutes to twenty-one minutes depending on load configuration, packing configuration, and load size. These are true “start-to-finish” cycle times (door locked to door unlocked). No instrument drying cycle is required.
15. Can the RapidHeat Sterilizer replace “Immediate-Use” sterilization practices?
RapidHeat sterilizers have pre-set sterilization cycles ranging from six minutes to twenty-one minutes depending on load configuration, packing configuration, and load size. These short sterilization cycle times and and no drying requirement makes HVHA technology an excellent choice to replace “Immediate-Use steam sterilization.” 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 needed in 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 RapidHeat Sterilizer equivalent to that of comparable tabletop steam sterilizers?
RapidHeat sterilizers have short sterilization cycle times which allow three to four complete sterilization cycles per hour. This results in a compatible or greater throughput of instruments on a per hour rate.
17. What is the comparative cost to operate the RapidHeat Sterilizer?
A Comparative Cost Analysis 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 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 RapidHeat sterilizers, providing a comparative energy analysis with two conventional tabletop steam sterilizers. As summarized in their report, the 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 HVHA sterilization process be monitored and recorded?
RapidHeat sterilizers monitor and record 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 HVHA sterilizer installation?
RapidHeat sterilizers only require a standard 110-120V, 60Hz, 15-amp service outlet. No water, drains or other utilities are required.