Low Temperature Sterilization

Modern healthcare is defined by rapid and continuous technological advances, with increasingly complex systems and medical devices entering routine clinical use ^[1]. More invasive operations are performed globally – and with them, the risk of transmitting pathogenic microorganisms via contaminated equipment ^[3]. Device-associated hospital-acquired infections are linked to prolonged hospital stays, increased risk of sepsis, and higher mortality in intensive care units ^[14]. Sterilization of medical devices is therefore a cornerstone of hospital infection control.

At the same time, advances in biomaterial and device technology, increasing emphasis on sustainability, including reduced reliance on toxic agents such as ethylene oxide ^[6], together with stricter validation and regulatory compliance requirements ^[6],^[11],^[8], are reshaping how medical devices are reprocessed in clinical settings.

Why LTS matters for heat- and moisture-sensitive devices

Today’s surgical inventories increasingly include sophisticated, delicate instruments used in minimally invasive and robotic-assisted procedures. Endoscopes, cameras, 3D-printed implants, ultrasonic transducers, or electronic sensors contain polymers, elastomers, adhesives, electronic and optic components, and complex device geometries. These technologies are sensitive to high temperatures and moisture, and exposure to the heat and humidity -typical of conventional steam sterilization- can lead to material degradation, mechanical issues, or functional failure ^[1],^[9],^[2],^[12].

Low temperature sterilization (LTS) refers to a group of sterilization methods used to reprocess heat- and moisture-sensitive medical devices and is widely applied in Central Sterile Supply Departments (CSSDs). 

LTS operates at temperatures well below those used in steam sterilization (121°C-134°C), typically between 37°C and 60°C, and utilize chemical sterilants in gaseous or liquid form, keeping device temperatures below about 60°C while still achieving a sterility assurance level of 10⁻⁶ ^[2].

Which LTS method is the best for my setting?

Several low-temperature sterilization methods are applied globally in healthcare settings, each with distinct mechanisms, advantages, and limitations. Here are the most common:

1.     Ethylene Oxide (EtO) Sterilization

EtO has been the most common low-temperature sterilant in U.S. healthcare facilities since the 1950s ^[2] and has a long history. It eliminates microorganisms by changing the protein molecules in microbial cells ^[1]. EtO is subject to intensive oversight by OSHA and the EPA due to environmental and occupational safety concerns ^[6],^[7], and the FDA is encouraging transitions to alternative sterilization methods ^[11].

• Advantages: EtO is highly versatile, offering broad material compatibility and exceptional penetration of complex device designs, including long and narrow lumens, and even large pallets of medical packaging including cardboard ^[12],^[18],^[2].
• Disadvantages: EtO is toxic, carcinogenic, and flammable ^[2],^[12]. Because the gas is absorbed by materials, lengthy aeration periods are required to remove hazardous residues, resulting in total cycle times that often exceed 12 hours ^[12],^[18],^[2].

2.     Low-Temperature Steam and Formaldehyde (LTSF)

LTSF combines sub-atmospheric steam at approximately 60–80 °C with formaldehyde gas, which reacts with microbial proteins to sterilize heat-sensitive devices that can tolerate some moisture ^[1].

• Advantages: LTSF offers easy penetrability and fast speed ^[3], good material compatibility, is cost-effective to operate, and allows sterilization within soft packaging or containers ^[1]. For slender lumen instruments, effective sterilization can be achieved ^[3].
• Disadvantages: Formaldehyde is a hazardous substance regulated for its toxicity and requires dedicated automated systems to ensure safe handling and effective removal ^[1].

3.     Hydrogen Peroxide (vH2O2) and Gas Plasma

Hydrogen Peroxide (VH2O2) and Gas Plasma

Scientific consensus increasingly categorizes both "vapor-only" and "plasma-assisted" systems under the broader definition of oxidative sterilization. While distinct in hardware, recent literature suggests that the primary lethal agent in both technologies is the hydrogen peroxide vapor itself, rather than the plasma state ^[21].

Advantages

• Active Residue Removal (Plasma Phase): The distinct advantage of applying radiofrequency energy (plasma) is its ability to actively dissociate hazardous residues. By generating plasma at the end of the process, residual hydrogen peroxide molecules are rapidly broken down into non-toxic water vapor and oxygen, ensuring the safety of the load for immediate handling ^[22]
• Deep Lumen Penetration (Vapor Phase): The vaporized hydrogen peroxide component possesses superior diffusion capabilities, allowing it to navigate complex geometries. Academic reviews confirm that sterilization within long, narrow lumens is achieved specifically by the vapor molecules reaching these surfaces, as the gas plasma itself cannot propagate into such restricted spaces ^[23].
• Rapid Cycle Times: Both variations of this technology offer significantly faster turnover times compared to ethylene oxide or steam. The oxidative efficiency of the vapor allows for rapid microbial inactivation at low temperatures, making these systems ideal for high-volume processing of heat-sensitive inventory ^[24].

Disadvantages

• Limited Plasma Reach: A critical limitation of the plasma phase is that it is a surface phenomenon with shallow penetration depth. Research demonstrates that the antimicrobial activity of the plasma energy does not extend into the interior of long tubes, meaning it does not contribute to the sterilization of internal device surfaces ^[21].
• Hardware Complexity and Cost: Systems that require plasma generation involve complex components, such as radiofrequency coils and matching networks. This added complexity can increase the potential for technical failure and maintenance costs compared to systems that rely solely on the injection and removal of vapor ^[21].
• Material Incompatibility (Absorbents): Neither system type is compatible with cellulose (paper), linens, or liquids, as these materials absorb the hydrogen peroxide oxidant. This absorption reduces the concentration available for sterilization and can lead to cycle cancellations or insufficient sterility assurance levels ^[22].

4.     Peracetic‑acid–based systems (PAA)

PAA is primarily used as an immersion sterilant for heat-sensitive endoscopes and provides strong sporicidal activity at room temperature. Liquid immersion systems are FDA-cleared for medical equipment, particularly for the high-level disinfection and sterilization of immersible devices like endoscopes ^[2],^[12]. Vaporized peracetic acid (VPA) remains a technology under development and has not yet received FDA clearance for healthcare facilities ^[2],^[12].

• Advantages:PAA provides rapid antimicrobial and sporicidal activity and decomposes into acetic acid, water, and oxygen, leaving minimal residue after appropriate rinsing ^[19],^[20].
• Disadvantages:The agent can be corrosive to certain metals and materials without proper formulation and neutralization and is limited to fully immersible devices that require prompt use after processing ^[16],^[19].

When you are responsible for reprocessing delicate, heat-sensitive medical devices, low-temperature sterilization may be not a single solution. No single method is 100 % optimal, has its specific advantages/disadvantages ^[2]. The choice depends on device type, material compatibility, lumen design, turnover requirements, worker safety, emissions regulations, and financial situation.

Current advances in LTS

Developments focus on improved material compatibility, more reliable process control, and reduced environmental impact, driven in part by regulatory pressure to limit ethylene oxide use ^[2],^[12]. Developments include refined vaporized hydrogen peroxide (VH₂O₂) systems with shorter cycles, better performance in complex lumens, and lower residuals ^[15]. Emerging evidence confirms VH₂O₂ LTS preserves mechanical properties, dimensions, and biocompatibility of select 3D-printed materials over repeated cycles ^[9]. At the same time, enhanced monitoring and quality assurance is increasingly emphasized, including every-load biological monitoring, to address rising device complexity ^[18].

The Getinge Poladus 150 was recently introduced as a VH₂O₂ LTS system operating at up to 55 °C, designed to support short cycle times and higher throughput in sterile processing departments. Its process design and integration into digital workflow and traceability systems reflect current developments in LTS toward improved efficiency, tighter process control, and closer alignment with regulatory requirements.

Key messages

• Sterilization of medical devices remains a cornerstone of hospital infection control, particularly as device-associated HAIs continue to contribute to morbidity, prolonged hospitalization, and increased mortality in intensive care units.
• The growing use of complex, heat- and moisture-sensitive medical devices limits the applicability of conventional steam sterilization and increases reliance on low-temperature sterilization (LTS).
• LTS enables effective reprocessing of delicate devices at temperatures between 37 °C and 60 °C while achieving a sterility assurance level of 10⁻⁶.
• No single LTS method is universally optimal. Ethylene oxide, hydrogen peroxide–based systems, low-temperature steam and formaldehyde, and peracetic acid each have distinct advantages and limitations.
• Among available LTS modalities, hydrogen peroxide–based systems offer particular advantages in terms of short cycle times, absence of toxic residues, and reduced environmental and occupational exposure compared with ethylene oxide.
• Hydrogen peroxide–based LTS is widely established for reprocessing heat-sensitive instruments and is supported by regulatory clearance for many device types, including electronics and optical components.
• Selection of an appropriate LTS modality should be guided by device design and materials, lumen complexity, turnaround requirements, worker safety considerations, regulatory requirements, and economic factors.