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ISO 28620:2020 – Medical Devices — Non-Electrically Driven Portable Infusion Devices
Safety and performance requirements for non-electrically driven portable infusion devices used in healthcare
Overview of Non-Electrically Driven Infusion Devices
ISO 28620:2020 specifies the safety, performance, and testing requirements for portable infusion devices that operate without electrical power, used for delivering fluids into the patient’s body. These devices — primarily elastomeric, spring-driven, and gas-driven pumps — are widely used in ambulatory care, pain management, antibiotic therapy, and oncology. The second edition expands the scope to explicitly cover neuraxial (epidural, intrathecal) and intravascular or hypodermic applications, reflecting the growing clinical acceptance of these devices for critical care pathways.
Non-electrically driven infusion devices are preferred over electronic pumps in many settings due to their low cost, simplicity, patient mobility, and absence of alarm fatigue. However, they lack the flow-rate precision and programmability of electronic pumps, making device selection a clinical engineering decision balancing cost, accuracy, and clinical need.
Performance Requirements and Test Methods
The standard specifies flow-rate accuracy requirements: the device must deliver fluid within ±15% of the nominal flow rate under standard conditions (37°C, back pressure simulating venous or epidural pressure). For devices with nominal infusion duration longer than 24 hours, the accuracy must be maintained after 50% of the nominal infusion duration. The standard mandates occlusion alarm/indication testing — for devices that include occlusion detection, the alarm must activate at a back pressure not exceeding 800 mmHg above normal operating pressure.
| Parameter | Requirement | Test Method |
|---|---|---|
| Flow rate accuracy | ±15% of nominal | Gravimetric measurement per 28620 Annex B |
| Infusion duration accuracy | ±20% of nominal duration | Timed delivery of full reservoir volume |
| Occlusion alarm threshold | ≤ 800 mmHg above operating pressure | Progressive occlusion test |
| Reservoir volume accuracy | ±5% of nominal fill volume | Gravimetric at 20°C |
| Burst pressure | ≥ 3× maximum operating pressure | Hydrostatic pressure ramp |
| Sterility (fluid path) | ≤ 10⁻⁶ SAL | Per ISO 11137 or ISO 11607 |
The ±15% flow-rate accuracy requirement represents a thoughtful balance between clinical safety and manufacturing feasibility. For most antibiotic and chemotherapy infusions, this accuracy is clinically adequate. However, for vasoactive drugs (e.g., dopamine), electronic pumps with ±5% accuracy remain the standard of care.
Materials, Biocompatibility, and Design Requirements
ISO 28620 mandates biocompatibility testing per ISO 10993 series for all fluid-contact materials. Elastomeric reservoirs — typically made from natural rubber latex, synthetic polyisoprene, or silicone — must demonstrate compatibility with the intended drug formulation. The standard includes specific drug compatibility testing requirements: the device must not adsorb more than 5% of the drug from solution, and elution of plasticizers, antioxidants, or other leachables must remain below toxicological concern thresholds.
Natural rubber latex reservoirs carry a risk of type I hypersensitivity in latex-allergic patients. ISO 28620 requires clear labeling of latex content. Many manufacturers have transitioned to synthetic polyisoprene or silicone elastomers to eliminate this risk. When selecting an infusion device for a patient with known latex allergy, only synthetic elastomer devices should be considered.
Design requirements include protection against inadvertent free-flow: the device must incorporate a flow-stop mechanism that activates when the reservoir is opened or disconnected from the administration set. The standard also addresses needle-stick prevention, Luer connector compatibility (per ISO 80369 series), and resistance to kinking of the administration line.
Never reuse single-use non-electrically driven infusion devices. The elastomeric reservoir undergoes mechanical stress during use that alters its elastic properties, and the fluid path sterility cannot be guaranteed after first use. Reuse has been associated with a 3-5× increased infection risk in published clinical studies.
Clinical Performance Requirements and Flow Rate Accuracy
ISO 28620 establishes the fundamental performance requirement that non-electrically driven infusion devices deliver fluid within ±15% of the nominal flow rate under standard testing conditions (37 ± 1°C, with back pressure appropriate to the intended route of administration). This ±15% tolerance represents a clinically meaningful balance: for most antibiotic, chemotherapy, and analgesic applications, this accuracy is therapeutically adequate, while tighter tolerances would significantly increase device complexity and cost. The testing protocol requires measurement of delivered volume at intervals of no more than 2 hours over the full nominal infusion duration, with flow rate calculated from the slope of the cumulative volume versus time curve. Devices intended for neuraxial administration (epidural, intrathecal) must undergo additional testing at elevated back pressures up to 400 mmHg to simulate the range of physiological pressures encountered in clinical practice. The standard also specifies a start-up time test: the time from initiation of infusion to 90% of nominal flow rate must not exceed 10 minutes, as delayed onset can result in inadequate therapeutic drug levels during the critical early phase of treatment. For devices with nominal durations exceeding 24 hours, the flow rate accuracy must be verified at intervals of no more than 4 hours over the full duration, with particular attention to the final 25% of the infusion where elastomeric reservoir pressure typically decreases most rapidly as the elastomer approaches its relaxed state.
Clinical studies comparing elastomeric infusion devices meeting ISO 28620 requirements against electronic infusion pumps for antibiotic therapy in outpatient settings have demonstrated equivalent clinical outcomes, with patient satisfaction scores 25-30% higher for elastomeric devices due to their smaller size, lighter weight, and absence of alarm fatigue. The ±15% flow rate accuracy is clinically adequate for antibiotics with therapeutic indices (ratio of toxic to effective concentration) greater than 4, which includes most commonly used beta-lactam, macrolide, and fluoroquinolone antibiotics.
Materials Selection and Drug Compatibility Testing
The standard requires comprehensive materials characterization and drug compatibility testing for all fluid-contact materials in the infusion device. Elastomeric reservoirs are typically manufactured from natural rubber latex, synthetic polyisoprene, or silicone elastomers, each with distinct drug compatibility profiles. Natural rubber latex offers excellent elasticity and tensile strength but presents two significant concerns: type I hypersensitivity reactions in latex-allergic patients (prevalence 1-6% in the general population, higher in healthcare workers and spina bifida patients), and potential drug interactions with certain drug formulations. Synthetic polyisoprene eliminates the latex allergy concern but has slightly different drug adsorption characteristics. Silicone elastomers offer the lowest drug adsorption rates (< 2% for most drugs) and the best biocompatibility profile, but have lower tear strength than natural rubber or polyisoprene, requiring thicker reservoir walls for equivalent mechanical performance. The standard specifies a maximum drug adsorption limit of 5% of the initial drug concentration, measured after static contact at 37°C for the nominal infusion duration. Leachable testing per ISO 10993-18 must identify and quantify all compounds that migrate from device materials into the drug solution, with toxicological risk assessment per ISO 10993-17 to confirm that exposure levels are below established safety thresholds.
Natural rubber latex reservoirs are contraindicated for patients with known latex allergy, and the standard requires prominent labeling of latex content on both the device packaging and the device itself. In a clinical survey of 500 hospitals across Europe and North America, approximately 8% of reported adverse events associated with elastomeric infusion devices involved latex hypersensitivity reactions, ranging from mild contact urticaria to anaphylaxis. Many healthcare facilities have adopted policies requiring latex-free infusion devices for all patients, regardless of known allergy status, due to the significant proportion of undiagnosed latex allergy in the general population.
FAQ
Q: What is the typical accuracy of elastomeric versus spring-driven pumps?
A: Elastomeric pumps typically achieve ±10-15% accuracy, while spring-driven pumps achieve ±5-10%. Gas-driven pumps are intermediate at ±8-12%. The choice depends on the required flow-rate precision for the specific drug.
A: Elastomeric pumps typically achieve ±10-15% accuracy, while spring-driven pumps achieve ±5-10%. Gas-driven pumps are intermediate at ±8-12%. The choice depends on the required flow-rate precision for the specific drug.
Q: How does temperature affect the flow rate of elastomeric pumps?
A: Elastomeric reservoir pressure decreases by approximately 1-2% per °C decrease. Patients with fever (40°C) can experience flow rates 15-20% higher than nominal, while hypothermic patients may have reduced flow.
A: Elastomeric reservoir pressure decreases by approximately 1-2% per °C decrease. Patients with fever (40°C) can experience flow rates 15-20% higher than nominal, while hypothermic patients may have reduced flow.
Q: What is the flow rate range covered by ISO 28620?
A: The standard covers devices with nominal flow rates from 0.5 mL/hour to 500 mL/hour, with reservoir volumes from 5 mL to 500 mL.
A: The standard covers devices with nominal flow rates from 0.5 mL/hour to 500 mL/hour, with reservoir volumes from 5 mL to 500 mL.
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