Usability study of pH strips for nasogastric tube placement

Aims
(1) To model the process of use and usability of pH strips (2) to identify, through simulation studies, the likelihood of misreading pH strips, and to assess professional’s acceptance, trust and perceived usability of pH strips.
Methods
This study was undertaken in four phases and used a mixed method approach (an audit, a semi-structured interview, a survey and simulation study). The three months audit was of 24 patients, the semi-structured interview was performed with 19 health professionals and informed the process of use of pH strips. A survey of 134 professionals and novices explored the likelihood of misinterpreting pH strips. Standardised questionnaires were used to assess professionals perceived usability, trust and acceptance of pH strip use in a simulated study.
Results
The audit found that in 45.7% of the cases aspiration could not be achieved, and that 54% of the NG-tube insertions required x-ray confirmation. None of those interviewed had received formal training on pH strips use. In the simulated study, participants made up to 11.15% errors in reading the strips with important implications for decision making regarding NG tube placement. No difference was identified between professionals and novices in their likelihood of misinterpreting the pH value of the strips. Whilst the overall experience of usage is poor (47.3%), health professionals gave a positive level of trust in both the interview (62.6%) and the survey (68.7%) and acceptance (interview group 65.1%, survey group 74.7%). They also reported anxiety in the use of strips (interview group 29.7%, survey group 49.7%).
Conclusions
Significant errors occur when using pH strips in a simulated study. Manufacturers should consider developing new pH strips, specifically designed for bedside use, that are more usable and less likely to be misread.

研究目的
(1) 构建pH试纸（pH strips）的使用流程与使用性能模型；(2) 通过模拟实验明确pH试纸的误读概率，并评估专业人员对pH试纸使用的接受度、信任度与感知易用性。

研究方法
本研究分为四个阶段，采用混合研究方法，涵盖审计调研、半结构化访谈、问卷调查与模拟实验。本次为期3个月的审计调研纳入24名患者，19名医疗卫生专业人员参与半结构化访谈，该访谈用于明确pH试纸的使用流程。针对134名专业人员与新手开展问卷调查，探究pH试纸的误判概率。在模拟实验中，采用标准化问卷评估专业人员对pH试纸使用的感知易用性、信任度与接受度。

研究结果
审计调研结果显示，45.7%的案例无法完成吸引操作，54%的鼻胃管（NG-tube）置入操作需通过X光确认。所有受访对象均未接受过pH试纸使用的正规培训。模拟实验中，参与者在试纸判读环节的错误率最高达11.15%，该结果对鼻胃管置入相关决策具有重要影响。专业人员与新手在pH试纸pH值误判概率上无显著差异。尽管整体使用体验评分较低（47.3%），但医疗卫生专业人员在访谈（62.6%）与问卷调查（68.7%）中均表现出对pH试纸的较高信任度，且接受度良好（访谈组65.1%，问卷组74.7%）。此外，两类群体均反馈使用试纸时存在焦虑情绪（访谈组29.7%，问卷组49.7%）。

研究结论
模拟实验结果表明，使用pH试纸时存在显著的判读误差。生产商应考虑开发专为床边使用设计的新型pH试纸，提升其易用性并降低误读概率。