In pharmaceutical and biological laboratories, where stringent sterile environments are crucial, vaporized hydrogen peroxide sterilization is a key method for ensuring the safety of the environment and materials. However, many people often overlook the fact that the effectiveness of sterilization is closely related to the loading process. If the loading layout is unreasonable or the items are not placed correctly, even the most advanced sterilization equipment may be significantly less effective. Today, we will focus on the loading process of vaporized hydrogen peroxide sterilization, breaking down the core requirements and safety precautions to help make sterilization operations in relevant scenarios more precise and efficient.
I. Core Loading Principles - Avoid Overcrowding and Ensure Compatibility
1. Ensure free circulation of the sterilant: The loading configuration must allow hydrogen peroxide gas to diffuse fully and evenly within the sterilization chamber and come into contact with all surfaces of the items.
2. Avoid the "shielding effect": Items must not be packed too densely or stacked, to prevent the formation of "dead zones" that the gas cannot penetrate.
3. Compatibility and safety: All items and packaging materials must be compatible with the hydrogen peroxide sterilization process and must not interfere with the normal operation of the sterilization chamber.
II. General Loading Requirements: Loading Quantity, Placement, and Packaging Requirements
0.1. Loading capacity should follow the sterilizer manufacturer's instructions; generally, the loading capacity should not exceed 70-80% of the sterilization chamber volume. "Underloading" is safer than "overloading" and ensures better sterilization results.
02. Item Placement: A. Vertical placement: Instrument trays and containers should be placed vertically, like books on a shelf, to expose the maximum surface area, facilitating gas penetration and removal. B. Spaced placement: A gap of at least 1-2 cm should be maintained between items, and the same horizontal layer should not be overloaded. C. Avoid contact: Items should not touch the inner wall, door, or electrodes (if any) of the sterilization chamber to maintain the gas circulation path. D. Long lumen instruments: Must be placed horizontally, ensuring no liquid residue remains inside the lumen, and adhering to the manufacturer's length/diameter limitations.
03. Packaging Requirements: A. Must use specialized packaging materials: such as Tyvek® bags, polypropylene non-woven fabric, or specialized transparent sterilization bags. The use of cotton cloth, paper-plastic bags (unless explicitly compatible), cellophane, or ordinary plastic bags is strictly prohibited.
B. Appropriate packaging size: Packaging should not be too large. When using bags, the sealed end should face upwards, and the packaging should not be too tight, leaving space inside for gas entry.
C. Proper sealing: Ensure the packaging is intact and undamaged, and the seal is tight.
III. Loading Restrictions and Material Requirements for Loaded Items
01. Absolutely Prohibited Items
A. Absorbent materials: such as cotton balls, gauze, cloth towels, paper, and wood products. These will absorb hydrogen peroxide, leading to sterilization failure and potential damage to the equipment.
B. Liquids, oils, and powders.
C. Single-use items (such as disposable sutures).
D. Incompletely dried items: Residual moisture will dilute hydrogen peroxide, severely affecting the sterilization effect. Instruments must be thoroughly dried.
E. Instruments containing copper, carbon steel, galvanized materials, brass, lead, or zinc (unless explicitly approved by the sterilizer manufacturer), as these materials may be corroded or affect plasma generation.
02. Special Requirements for Lumen Instruments
A. Length and Diameter (L/D ratio): The maximum length-to-inner diameter ratio specified by the equipment manufacturer must be strictly adhered to (e.g., lumen length limitation for inner diameters ≤2mm).
B. Lumen adapters must be used: To ensure effective gas injection and removal from the lumen.
C. Clean and Dry: The lumen must be thoroughly cleaned, free of any biofilm or organic residue, and completely dry.
03. Instrument Trays and Containers
A. A dedicated instrument tray with mesh and no lid must be used to ensure that gas can freely penetrate from all sides.
B. Instruments in the tray should be placed in a single layer, without stacking or crowding. Complex instruments should be disassembled into their smallest components.
C. Containers with sealed lids or enamel/metal trays are strictly prohibited.
04. Mixed Loading: Avoid mixing items with significantly different characteristics (such as large instruments and delicate endoscopes). If mixed loading is necessary, the most difficult-to-sterilize items (such as long lumens) should be placed in the most easily exposed position (usually the upper shelf).
IV. Rules for Placing Indicators
In the VHP (vaporized hydrogen peroxide) sterilization loading process, the correct placement of indicators is a critical step in verifying sterilization effectiveness and ensuring uniform and reliable sterilization. The core objective is to accurately capture the sterilization status at the "most difficult-to-sterilize point," thereby avoiding safety risks caused by inadequate sterilization in certain areas.
Chemical Indicators (CI): Used for quick and visual assessment of whether items have undergone a complete VHP sterilization cycle (e.g., whether they have been exposed to the specified concentration of VHP gas and reached the set sterilization time). Results are shown through color changes (e.g., from yellow to purple). Suitable as a "routine monitoring tool" for each batch of loaded items, and should be placed with each package/box of items.
Biological Indicators (BI): Used to accurately verify whether the sterilization effect meets the microbial inactivation standard (usually requiring 6-log inactivation of *Bacillus subtilis* or *Geobacillus stearothermophilus*). This is the gold standard for determining whether sterilization is "truly qualified," and should be placed for each batch or critical load (such as precision instruments, high-risk items).
Core Placement Principle: Focus on the "most difficult sterilization points," covering the entire area.
The core logic of indicator placement is to "simulate the worst-case scenario," that is, prioritizing the placement of indicators in locations where VHP gas is most difficult to penetrate and sterilization conditions are the worst, while also ensuring full coverage of the loading area to avoid blind spots in monitoring. Specific principles include:
1. Prioritize the most difficult sterilization points:
Combining the gas flow path of the VHP sterilization chamber (usually diffusing from the air inlet to the outlet, with corners and the center of the load prone to dead zones), focus on the following locations: the central area of the loading tray, the bottom of the lowest tray in multi-layer loading, the inside of the lumen of tubular instruments, the inner corners of instrument boxes, and the rear corners of the sterilization chamber (away from the air inlet).
2. Ensure "same environment" as the items:
The indicators must maintain the same placement posture and contact environment as the items being sterilized, avoiding direct exposure to the VHP air inlet (to avoid misjudgment due to excessively high local concentration), and also avoiding being blocked or isolated by items (e.g., not placed in a sealed container). For example, indicators for tubular instruments should be placed inside the lumen, and indicators for boxed instruments should be placed in the innermost part of the box (in contact with the instruments). 3. Comprehensive Coverage to Avoid Omissions:
For large sterilization chambers or multi-tray loads, indicators should be placed according to the "zonal distribution" principle to ensure that each loading area (upper layer, lower layer, left side, right side, center, and edge) has indicators. At least three sets of biological indicators should be placed in each batch, located at the most difficult sterilization point, the center of the load, and the edge of the load. At least one chemical indicator should be placed in each package/box.
V. Loading Operation Procedure: Inspection / Planning / Loading / Verification / Recording
1. Inspection: Check that items are clean, dry, compatible, and correctly packaged.
2. Planning: Plan the placement in advance based on the sterilization chamber shelf levels, following the "vertical and spaced" principle.
3. Loading: Place items gently, avoiding contact with the chamber walls. Place long instruments horizontally, and other instrument trays vertically.
4. Verification: After loading, observe from outside the chamber door to confirm that no items are protruding, touching the door or electrodes, and that the gas circulation path is unobstructed.
5. Recording: For special or complex loading, it is recommended to record the loading method for traceability.
✅ [Do] ▶▶ Thoroughly clean and dry, use compatible packaging, place vertically, maintain spacing, use adapters for lumen instruments, and comply with the L/D ratio.
❌ [Do Not] ▶▶ Use absorbent materials, overload, stack instrument trays horizontally, use prohibited packaging (cloth, paper), or load liquids or powders.
