结论：先把宣称定清楚，再谈验证什么
「防压疮坐垫」这个说法涵盖的范围很宽，而不同的宣称需要不同的证据。
如果宣称的是「降低界面压力」，验证压力分布即可；如果宣称的是「预防压疮」，那涉及临床效果，压力数据只是间接证据。 两者的举证难度差着数量级。
所以准备验证之前，先把宣称的表述定下来。表述写得越具体、越贴近可测量的物理量，举证越容易；写得越接近临床结果，要求的证据层级越高。
可验证的性能维度
压疮的发生与几个因素相关，坐垫能影响的主要有四个：
| 维度 | 坐垫的作用 | 可测量性 |
|---|---|---|
| 界面压力 | 分散载荷，降低峰值 | 可直接测量 |
| 剪切力 | 减少组织侧向受力 | 可测量，方法相对复杂 |
| 微气候 | 影响接触面的温湿度 | 可测量 |
| 稳定性 | 影响坐姿维持，间接影响受力 | 可通过姿势保持测量 |
第二行和第三行常被忽略。 压疮的成因不只是垂直压力——剪切力会使组织变形，湿热环境会降低皮肤耐受性。只测压力而不考虑这两项，评价是不完整的。
各维度的测试方法
界面压力。 用压力分布阵列测量，读取峰值压力、接触面积、压力梯度。条件要严格控制并记录。
剪切力。 需要能同时测量法向和切向力的传感设备，或者通过特定的位移加载方式评价。比压力测量复杂，但对于宣称减少剪切的产品是必要的。
微气候。 在接触面测量温度与湿度随时间的变化。透气性差的材料会使接触面温湿度上升，这与皮肤耐受性相关。
姿势稳定性。 评价使用者在坐垫上的姿态保持能力。不稳定的坐垫会导致使用者频繁调整，或者出现骨盆倾斜，反而增加局部受力。
宣称与证据的对应
建议把宣称拆成可验证的陈述，逐条对应证据：
宣称降低峰值压力——提供与参照产品的对比数据；宣称改善压力分布——提供接触面积与分布图；宣称减少剪切——提供剪切力测量数据；宣称改善微气候——提供温湿度数据；宣称维持姿势——提供姿势保持的评价数据。
凡是宣称里出现的性能，都应当有对应数据。 没有数据支撑的宣称，在监管和采购两个环节都可能被挑出来。
对比试验的设计
这类产品的数据多数以对比形式呈现——与普通坐垫比、与竞品比。设计对比试验时要注意：
条件必须完全一致。 同一加载对象、同一重量、同一坐姿、同一测量时机、同一环境温度。
参照物要说明。 与什么比较，参照产品的规格是什么。
样本量要足够。 单次测量的差异可能来自偶然因素。
差异要有意义。 测出来的差异要大到具有实际意义，而不只是统计上可分辨。
对比数据如果条件没说清楚，说服力会大打折扣，尤其是在与竞品比较的场合。
使用中的配合条件
坐垫的效果依赖正确使用，这一点应当在说明书中讲清楚：
坐垫的正反面与前后方向；适用的体重范围；空气类坐垫的充气量调节；需要配合使用的姿势与摆位；以及定期减压的重要性——坐垫降低压力但不能消除压力，长时间不动仍然有风险，定期变换姿势是必要的。
最后这一条尤其重要。如果使用者以为用了防护坐垫就可以长时间不动，风险反而可能增加。
与耐久的关系
所有防护性能都会随使用衰减：泡沫压实、凝胶流动、空气单元漏气。新品数据不能代表使用期内的表现。
建议做耐久后的性能复测，并据此给出更换周期建议。对于防护类产品，这项数据的价值明显——它回答的是「这个垫子还有没有防护作用」，而使用者从外观上判断不了。
参照产品的选择
对比试验里，参照产品选得对不对直接影响结论的说服力。几条建议：
与同类产品比，不要与明显更差的产品比。 和一块普通泡沫板比出优势，说明力有限。
参照产品的规格要说明。 厚度、材料、状态（新品还是使用过的）。
如果与竞品比，数据的使用要谨慎。 对比数据用于内部研发参考没有问题，用于对外宣传时要考虑表述方式和法律风险。
与自家前代产品比是稳妥的选择。 既能体现改进，又不涉及与他人产品的比较。
数据的使用场景
这类验证数据主要有三个用处，各自对数据的要求不同：
| 用途 | 数据要求 |
|---|---|
| 内部研发比选 | 相对比较即可，条件一致 |
| 注册资料 | 方法可追溯，条件完整记录 |
| 对外宣传 | 表述与数据严格对应，避免延伸 |
第三项的风险分量最重。 从「峰值压力低于参照产品」推到「预防压疮」，中间跳过了多个环节。宣传文案应当贴着数据写，不做外推。
建议在测试完成后，由技术人员把数据能支撑的结论明确写出来，作为市场部门撰写文案的依据。这一步做了，能避免后续很多麻烦。
与使用者评估的配合
产品层面的测试用标准条件做比较，而实际配置时需要针对个体。两者的关系是：
产品测试回答的是「这个垫子在标准条件下表现如何」，用于产品选型的初筛和产品间的比较。
个体评估回答的是「这个垫子适不适合这个人」，需要考虑体型、坐姿、活动能力、风险等级和使用时长。
产品数据做得好，能缩小个体评估时的候选范围，但不能替代个体评估。 说明书里应当把这层意思讲清楚，避免使用者以为买了防护垫就万事大吉。
对制造商来说，提供清晰的适用范围说明（适用体重、适用体型、推荐的风险等级）比笼统地说「适合所有人」更有价值，也更容易被专业人员采纳。
我们的做法
做这类验证时，我们会先与委托方确认宣称的具体表述，再据此确定测试维度。宣称不明确就开测，容易测了一堆数据却支撑不了想说的话。
对于以防护为核心卖点的产品，建议把耐久后复测纳入方案。这组数据在采购方比较时是加分项，因为多数产品只提供新品数据。
有需要可以把产品结构和计划的宣称表述发过来一起设计验证，或者直接联系：132 4819 8029。检测能力见服务介绍，产品分类见手动轮椅检测与电动轮椅检测，标准信息见标准查询。
English version
Conclusion. The term pressure-relieving cushion covers a wide range, and different claims require different evidence. A claim to reduce interface pressure is supported by pressure distribution measurement. A claim to prevent pressure ulcers concerns clinical outcome, for which pressure data are only indirect evidence. The two differ by an order of magnitude in what must be demonstrated. Settle the wording of the claim before planning verification: the more specific the claim and the closer it stays to measurable physical quantities, the easier it is to support; the closer it moves to clinical outcome, the higher the level of evidence required.
Verifiable dimensions. Pressure ulcer development relates to several factors, of which a cushion can influence four. Interface pressure, where the cushion distributes load and reduces peaks, is directly measurable. Shear, where the cushion reduces lateral loading of tissue, is measurable with more complex methods. Microclimate, where the cushion affects temperature and humidity at the interface, is measurable. And stability, where the cushion affects posture maintenance and so indirectly affects loading, can be assessed through posture retention. The second and third are commonly overlooked: pressure ulcers do not arise from normal pressure alone, since shear deforms tissue and a warm humid interface reduces skin tolerance. Measuring pressure alone gives an incomplete evaluation.
Methods. Interface pressure is measured with a pressure mapping array, reading peak pressure, contact area and gradient, under conditions that must be controlled and recorded. Shear requires equipment capable of measuring normal and tangential force simultaneously, or evaluation through defined displacement loading; it is more involved than pressure measurement and is necessary where shear reduction is claimed. Microclimate is measured as temperature and humidity at the interface over time, since poorly breathing materials raise both and that relates to skin tolerance. Postural stability assesses how well the user maintains position, since an unstable cushion causes frequent readjustment or pelvic obliquity, which can increase local loading.
Matching claims to evidence. Break the claim into verifiable statements and match each to evidence. A claim of reduced peak pressure needs comparative data against a reference. A claim of improved distribution needs contact area and distribution maps. A claim of reduced shear needs shear measurements. A claim of improved microclimate needs temperature and humidity data. A claim of postural support needs posture retention data. Every performance attribute appearing in a claim should have corresponding data; unsupported claims are liable to be picked up in both regulatory review and procurement evaluation.
Designing comparative testing. Data for these products are usually comparative, against a standard cushion or a competing product. Conditions must be identical, covering loading object, mass, posture, timing of measurement and ambient temperature. The reference must be identified, stating what it was compared against and the reference product's specification. Sample size must be adequate, since a single measurement may differ by chance. And differences must be meaningful, large enough to matter in practice rather than merely statistically distinguishable. Comparative data whose conditions are not stated carry much less weight, particularly when the comparison is against a competitor.
Conditions for effective use. Performance depends on correct use, and the instructions should be explicit about which way up and which way round the cushion goes, the applicable weight range, how to set inflation on air cushions, the posture and positioning to be used alongside it, and the importance of regular pressure relief. A cushion reduces pressure without eliminating it, and remaining motionless for long periods still carries risk, so changing position regularly remains necessary. That last point matters particularly: a user who believes a protective cushion permits sitting still indefinitely may face greater risk rather than less.
Relationship to durability. All protective performance declines with use as foam compacts, gel migrates and air cells leak. New-product data do not represent behaviour across the service period. Remeasure after durability cycling and use the result to recommend a replacement interval. For protective products this data is clearly valuable, because it answers whether the cushion still protects, which users cannot judge by appearance.
How we handle it. We agree the exact wording of the claim with the client before deciding which dimensions to test, because starting without a clear claim tends to generate data that does not support what the client wants to say. For products sold principally on protection we suggest including post-durability remeasurement, which counts in a purchaser's comparison since most products offer new-product data only.
Send us the construction and the intended claim wording and we will design the verification. Phone or WeChat: +86 132 4819 8029.