A Comprehensive Approach for the Ergonomic Evaluation of 13 Emergency and Transport Ventilators

The mental workload of ICU nurses performing human-machine tasks and associated factors: A cross-sectional questionnaire survey

AIMS

To assess the level of mental workload (MWL) of intensive care unit (ICU) nurses in performing different human-machine tasks and examine the predictors of the MWL.

DESIGN

A cross-sectional questionnaire study.

METHODS

Between January and February 2021, data were collected from ICU nurses (n = 427) at nine tertiary hospitals selected from five (east, west, south, north, central) regions in China through an electronic questionnaire, including sociodemographic questions, the National Aeronautics and Space Administration Task Load Index, General Self-Efficacy Scale, Difficulty-assessing Index System of Nursing Operation Technique, and System Usability Scale. Descriptive statistics, t-tests, one-way ANOVA and multiple linear regression models were used.

RESULTS

ICU nurses experienced a medium level of MWL (score 52.04 on a scale of 0-100) while performing human-machine tasks. ICU nurses' MWL was notably higher in conducting first aid and life support tasks (using defibrillators or ventilators). Predictors of MWL were task difficulty, system usability, professional title, age, self-efficacy, ICU category, and willingness to study emerging technology actively. Task difficulty and system usability were the strongest predictors of nearly all typical tasks.

CONCLUSION

ICU nurses experience a medium MWL while performing human-machine tasks, but higher mental, temporal, and effort are perceived compared to physical demands. The MWL varied significantly across different human-machine tasks, among which are significantly higher: first aid and life support and information-based human-machine tasks. Task difficulty and system availability are decisive predictors of MWL.

IMPACT

This is the first study to investigate the level of MWL of ICU nurses performing different representative human-machine tasks and to explore its predictors, which provides a reference for future research. These findings suggest that healthcare organizations should pay attention to the MWL of ICU nurses and develop customized management strategies based on task characteristics to maintain a moderate level of MWL, thus enabling ICU nurses to perform human-machine tasks better.

PATIENT OR PUBLIC CONTRIBUTION

No patient or public contribution.

Optimal Usability Test Procedure Generation for Medical Devices

Medical device usability testing offers many benefits, including finding medical device usage errors and providing safety to users. As usability testing becomes mandatory for medical devices, manufacturers are increasing the cost burden. In order to perform a high-quality usability test, it is important to implement a usability test procedure, but guidelines for this are lacking. In this paper, we propose a method to systematically design and implement a usability test procedure. We propose methods to reduce test time-costs and apply them to implement the final procedure. Next, by applying the proposed method to sinus surgical navigation system, it is shown that the total time was reduced by 21% compared to the usability summative test procedure previously used in the same system.

ST-T segment changes in prehospital emergency physicians in the field: a prospective observational trial

Aims

Due to time-critical decision-making, physical strain and the uncontrolled environment, prehospital emergency management is frequently associated with high levels of stress in medical personnel. Stress has been known to cause ischemia like changes in electrocardiograms (ECGs), including arrhythmias and deviations in ST-T segments. There is a lack of knowledge regarding the occurrence of changes in ST-T segments in prehospital emergency physicians. We hypothesized that ST-T segment deviations occur in prehospital emergency physicians in the field.

Methods

In this prospective observational trial, ST-T segments of emergency physicians were recorded using 12-lead Holter ECGs. The primary outcome parameter was defined as the incidence of ST-T segment changes greater than 0.1 mV in two corresponding leads for more than 30 s per 100 rescue missions. The secondary outcomes included T-wave inversions and ST-segment changes shorter than 30 s or smaller than 0.1 mV. Surrogate parameters of stress were measured using the NASA-Task Load Index and cognitive appraisal, and their correlation with ST-T segment changes were also assessed.

Results

Data from 20 physicians in 36 shifts (18 days, 18 nights) including 208 missions were analysed. Seventy percent of previously healthy emergency physicians had at least one ECG abnormality; the mean duration of these changes was 30 s. Significantly more missions with ECG changes were found during night than day shifts (39 vs. 17%, p < 0.001). Forty-nine ECG changes occurred between missions. No ST-T segment changes > 30 s and > 0.1 mV were found. Two ST-T segment changes < 30 s or < 0.1 mV (each during missions) and 122 episodes of T-wave inversions (74 during missions) were identified. ECG changes were found to be associated with alarms when asleep and NASA task load index.

Conclusion

ECG changes are frequent and occur in most healthy prehospital emergency physicians. Even when occurring for less than 30 s, such changes are important signs for high levels of stress. The long-term impact of these changes needs further investigation.

Trial registration The trial was registered at ClinicalTrials.gov (NCT04003883) on 1.7.2019: https://clinicaltrials.gov/ct2/show/NCT04003883?term=emergency+physician&rank=2

Association of ventilator type with hospital mortality in critically ill patients with SARS-CoV2 infection: a prospective study

Background

To evaluate the association between ventilator type and hospital mortality in patients with acute respiratory distress syndrome (ARDS) related to COVID-19 (SARS-CoV2 infection), a single-center prospective observational study in France.

Results

We prospectively included consecutive adults admitted to the intensive care unit (ICU) of a university-affiliated tertiary hospital for ARDS related to proven COVID-19, between March 2020 and July 2021. All patients were intubated. We compared two patient groups defined by whether an ICU ventilator or a less sophisticated ventilator such as a sophisticated turbine-based transport ventilator was used. Kaplan–Meier survival curves were plotted. Cox multivariate regression was performed to identify associations between patient characteristics and hospital mortality. We included 189 patients (140 [74.1%] men) with a median age of 65 years [IQR, 55–73], of whom 61 (32.3%) died before hospital discharge. By multivariate analysis, factors associated with in-hospital mortality were age ≥ 70 years (HR, 2.11; 95% CI, 1.24–3.59; P = 0.006), immunodeficiency (HR, 2.43; 95% CI, 1.16–5.09; P = 0.02) and serum creatinine ≥ 100 µmol/L (HR, 3.01; 95% CI, 1.77–5.10; P < 0.001) but not ventilator type. As compared to conventional ICU (equipped with ICU and anesthesiology ventilators), management in transient ICU (equipped with non-ICU turbine-based ventilators) was associated neither with a longer duration of invasive mechanical ventilation (18 [IQR, 11–32] vs. 21 [13–37] days, respectively; P = 0.39) nor with a longer ICU stay (24 [IQR, 14–40] vs. 27 [15–44] days, respectively; P = 0.44).

Conclusions

In ventilated patients with ARDS due to COVID-19, management in transient ICU equipped with non-ICU sophisticated turbine-based ventilators was not associated with worse outcomes compared to standard ICU, equipped with ICU ventilators. Although our study design is not powered to demonstrate any difference in outcome, our results after adjustment do not suggest any signal of harm when using these transport type ventilators as an alternative to ICU ventilators during COVID-19 surge.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13613-022-00981-2.

Causes of use errors in ventilation devices - Systematic review

A systematic review according to the PRISMA reporting standard was performed to identify causes of use errors in mechanical ventilators described in the literature. The PubMed search resulted in the inclusion of 16 papers. The errors described were systematically analyzed with regard to their causes and categorized in an adapted cause-and-effect diagram. The causes of use errors were related to specific usability issues and to the general condition that medical staff often work with different ventilators. When many devices are used, the different user interfaces are a source of use errors, since, for example, the same ventilation modes have different names. In order to avoid the identified causes for use errors in the future, this work offers manufacturers of ventilation devices design recommendations and the possibility to include the results in their risk management. In addition, standardizing user interface content across all ventilators, as in ISO 19223, can help reduce use errors.

Human factors/ergonomics to support the design and testing of rapidly manufactured ventilators in the UK during the COVID-19 pandemic

Background

This paper describes a rapid response project from the Chartered Institute of Ergonomics & Human Factors (CIEHF) to support the design, development, usability testing and operation of new ventilators as part of the UK response during the COVID-19 pandemic.

Method

A five-step approach was taken to (1) assess the COVID-19 situation and decide to formulate a response; (2) mobilise and coordinate Human Factors/Ergonomics (HFE) specialists; (3) ideate, with HFE specialists collaborating to identify, analyse the issues and opportunities, and develop strategies, plans and processes; (4) generate outputs and solutions; and (5) respond to the COVID-19 situation via targeted support and guidance.

Results

The response for the rapidly manufactured ventilator systems (RMVS) has been used to influence both strategy and practice to address concerns about changing safety standards and the detailed design procedure with RMVS manufacturers.

Conclusion

The documents are part of a wider collection of HFE advice which is available on the CIEHF COVID-19 website (https://covid19.ergonomics.org.uk/).

The usability of ventilator maintenance user interface: A comparative evaluation of user task performance, workload, and user experience

Poor usability designed of ventilator user interface can easily lead to human error. In this study, we evaluated the usability design of ventilator maintenance user interface and identified problems related to the usability of user interface that could easily cause human error. Sixteen respiratory therapists participated in this usability study. The usability of the ventilator maintenance user interface was evaluated by participants' task performance (task completion time, task error rate), physiological workload (eye-fixation duration) and perceived workload (NASA-TLX), and user experience (questionnaire). For task performance, task completion time and task error rate showed significant differences. For task completion time, significant difference was found when conducting ventilator self-test (p < 0.001), replace the breathing circuit (p = 0.047), and check battery status (p = 0.005). For task error rate, the three ventilators showed significant difference (p = 0.012), and the Serov I showed a significantly higher task error rate than the Boaray 5000D (p = 0.031). For workload, the Serov I was associated with higher physiological and perceived workloads than other ventilators (p < 0.05). For user experience, the Boaray 5000D received better scores among the ventilators in terms of ease to maintain, friendly to maintain, and willingness to use (p < 0.05, respectively). Our study adds available literature for usability evaluation of ventilator maintenance user interface. The results indicate that the maintenance user interface of the Boaray 5000D performed better than the other two tested ventilators. Moreover, the study results also proved that eye-fixation duration can be a reliable tool for evaluating the usability of ventilator user interface.

A Usability Study of 3 Radiotherapy Systems: A Comparative Evaluation Based on Expert Evaluation and User Experience

BACKGROUND The complex user interface design of radiotherapy treatment delivery systems can lead to use error and patient harm. In this study, we present the results of a comparison of 3 radiotherapy treatment delivery systems now used in China. MATERIAL AND METHODS We conducted a comprehensive usability study of 3 radiotherapy treatment delivery systems. Expert evaluation was performed through heuristic evaluation with 3 human-factors experts and 1 experienced radiation therapist for each system. User experience was assessed through perceived system usability and workload, using the National Aeronautics and Space Administration Task Load Index and the Post-Study System Usability Questionnaire. RESULTS For the expert evaluation, 47 usability problems were identified for Varian Trilogy, 75 for Elekta Precise, and 37 for Shinva XHA600E. Most problems were classified as major and minor usability problems, and were found in the process of patient setup and setup verification. For the user experience, radiation therapists presented a lower workload for Varian Trilogy compared to Elekta Precise (P<0.01) and Shinva XHA600E (P<0.01), and a lower workload for Elekta Precise compared to Shinva XHA600E (P=0.020). Radiation therapists perceived a higher system usability for Varian Trilogy compared to Shinva XHA600E (P<0.01), and a higher system usability for Elekta Precise compared to Shinva XHA600E (P<0.01). CONCLUSIONS This research provides valuable data on how 3 radiotherapy treatment delivery systems compare. The results of this study may be useful for hospital equipment procurement decisions, and designing next-generation products to improve patient safety.

Comprehensive Evaluation of User Interface for Ventilators Based on Respiratory Therapists' Performance, Workload, and User Experience

Background

Poor ergonomic design of ventilators can result in human errors. In this study, we evaluated the ergonomics of ventilators through respiratory therapists’ performance, workload, and user experience.

Material/Methods

Sixteen respiratory therapists were recruited to this usability study of 3 ventilators. Participants had to perform 7 tasks on each ventilator. Respiratory therapists’ performance was measured by task errors of all tasks for each participant. Workload was measured by objective measurement (blink rate and duration) and by subjective measurement (NASA-TLX). User experience was assessed by the USE Questionnaire.

Results

For task errors, significant differences were found among ventilators (p<0.05) and the Evital 4 received higher task errors when compared to the Servo I (p<0.05). For blink rate, significant differences were found in tasks of starting the ventilator, ventilator monitoring values recognition, ventilator setting parameters modification, alarm parameter recognition, and resetting among ventilators (p<0.05). Furthermore, blink duration was also found to be significant differently in tasks of starting the ventilator, mode and setting parameters recognition, ventilator monitoring values recognition, ventilator mode modification, and alarm parameter recognition and resetting, as well as in the average of all tasks (p<0.05). For perceived workload, the Evital 4 received higher NASA-TLX scores among ventilators. For user experience, the Servo I received the highest scores on the USE Questionnaire among the ventilators.

Conclusions

The study provides a comprehensive evaluation method of user interface based on respiratory therapists’ performance, workload, and user experience. In addition, this study suggests that the ergonomic design of the Evital 4 is poor. Finally, we found that eye motion (blink rate and duration) may be useful to assess the ergonomics of a user interface.

Usability Study of the User-Interface of Intensive Care Ventilators Based on User Test and Eye-Tracking Signals

BACKGROUND The aim of this study was to evaluate the ergonomics of the user-interface for 3 intensive care ventilators, and identify usability problems leading to user errors. MATERIAL AND METHODS Sixteen respiratory therapists were recruited to perform 6 specific user-interface operational tasks on ventilators. Data (task completion time, pupil diameter, average slope of pupil diameter change, and subjective evaluation) were collected through objective measurement, questionnaires, and an eye-tracking instrument. RESULTS For task completion time, there were significant differences among ventilators in recognition tasks of ventilator mode and settings (P<0.05), modification of ventilator modes and recognizing (P<0.05) and changing alarm settings (P<0.05). A mean of 15±2 task failures was observed for each ventilator. For the change of pupil diameter, a significant difference was observed between ventilators (except task 2, P<0.05). For average slope of pupil diameter change, a significant difference was also observed between ventilators (except task 2, P<0.05). The Servo I showed a better correlation between task completion time and pupil diameter change. The subjective evaluation results were clear: Evital 4 received worst scores in terms of friendliness of user-interface, information display and safety (respectively, P<0.05). CONCLUSIONS The present study provided valuable evidence to indicate the ergonomic of ventilators now used in China. With the result of this study, we can infer that the Evital 4 were poorly ergonomic designed. Furthermore, the study also demonstrated that eye-tracking can be a promising tool to evaluate the ergonomics of the user-interface.