Lotlikar recently demonstrated that the perceived usability of Macintosh-shaped videolaryngoscopes was inferior to direct laryngoscopes of the same profile [1]. While I fully agree that the design of tools used by our speciality is commonly overlooked and provides substantial opportunity to improve safety and efficiency, the comparison in this instance needs further context and is only a small part of the story.

The very nature of the two laryngoscopes compared are of different complexities with similar but not identical modes of use. A direct laryngoscope is a simple device with a handle, blade, batteries and light source. In comparison, a videolaryngoscope has complex electronics including a fibreoptic camera and image processor in addition to the familiar physical components of its ‘analogue’ partner.

Arguably, a similar comparison could be made, for example, between physically typed letters and emails – one requiring a typewriter and paper, the other a computer with an email user interface, internet connection, screens and a multitude of complicated components. In this case, both require similar physical steps of pressing keys to communicate an idea, but the broader task is potentially much more complex when the functioning of electronic devices is included.

The interpretation of the system usability scale should be undertaken cautiously [2]. It was initially derived in the 1980s to aid comparison of similar computer hardware and software products and through the development cycle. However, it has since become ubiquitous and valuable as a ‘quick and dirty’, adaptable human factors assessment tool. Scores are graded on a sigmoid-shaped curve (Fig. 1) with nearly all scores being found in the 40–80 point range and little perceived improvement over the upper 20 points [3]. Given the simplicity and duration of use of the direct laryngoscope (first introduced into practice in 1944), it is unsurprising that it scored exceptionally in the top 5% (A+ or Best imaginable), whereas the videolaryngoscope, despite an apparently high mark, scored barely in the top 50% (C+ or Good). Asking the question “I found the system unnecessarily complex” when comparing a simple device with a complicated one that achieves the same outcome is perhaps unfair. Indeed, in a previous study, a comparison between desk and mobile (cellular) phones showed statistically significantly higher system usability scale scores with the analogue versions. This outlines the imbalance of such direct score comparisons with similar devices of different technological eras [4].

The introduction of videolaryngoscopes has been a leap forward in the safe management of airways and in the last few years there has been a frenzy of comparisons between direct- and videolaryngoscopes [5, 6]. While we should always strive to improve the design, usability and safety of our tools, this simple comparison of one device against another belies the opportunities afforded by the technology and improved success rate. Merely boiling perceived usability down to a score fails to recognise these benefits. Future usability comparisons between videolaryngoscopes rather than with direct laryngoscopes will provide useful information but it should not be the only method to assess the utility of these devices. Usability needs to be understood in context and include effectiveness, efficiency and (as measured by the system usability scale) satisfaction. Success rates, time taken and additional patient-reported measures must remain the primary metrics for evaluation of airway devices.

Lotlikar 最近证明，Macintosh 形视频喉镜的感知可用性不如相同轮廓的直接喉镜 [1]。虽然我完全同意我们专业部门使用的工具设计经常被忽视，并为提高安全性和效率提供了大量机会，但在这种情况下的比较需要进一步的背景，并且只是故事的一小部分。

比较的两种喉镜的本质具有不同的复杂性，具有相似但不相同的使用模式。直接喉镜是一种带有手柄、刀片、电池和光源的简单设备。相比之下，电子喉镜具有复杂的电子元件，包括光纤摄像头和图像处理器，以及其“模拟”合作伙伴熟悉的物理组件。

可以说，例如，在物理打字的信件和电子邮件之间可以进行类似的比较——一个需要打字机和纸张，另一个需要具有电子邮件用户界面、互联网连接、屏幕和大量复杂组件的计算机。在这种情况下，两者都需要类似的物理步骤，即按下按键来传达想法，但是当包括电子设备的功能时，更广泛的任务可能要复杂得多。

应谨慎解释系统可用性量表 [2]。它最初是在 1980 年代衍生出来的，以帮助比较类似的计算机硬件和软件产品并贯穿整个开发周期。然而，它作为一种“快速而肮脏”、适应性强的人为因素评估工具变得无处不在和有价值。分数在 S 形曲线上分级（图 1），几乎所有分数都在 40-80 分范围内，与较高的 20 分相比几乎没有明显的改善 [3]。鉴于直接喉镜（于 1944 年首次引入实践）的简单性和使用时间，它在前 5% 的得分（A+ 或想象中的最佳）得分异常也就不足为奇了，而电子喉镜尽管得分明显很高，但得分勉强进入前 50%（C+ 或良好）。在将简单设备与实现相同结果的复杂设备进行比较时，提出“我发现系统不必要地复杂”的问题可能是不公平的。事实上，在之前的一项研究中，桌面电话和移动（蜂窝）电话之间的比较显示，模拟版本的系统可用性量表得分在统计学上显着更高。这概述了这种与不同技术时代的类似设备的直接分数比较的不平衡 [4]。

电子喉镜的引入是气道安全管理的一大飞跃，在过去几年中，直接喉镜和电子喉镜之间的比较非常激烈 [5， 6]。虽然我们应该始终努力改进工具的设计、可用性和安全性，但这种设备与设备的简单比较掩盖了技术提供的机会和提高的成功率。仅仅将感知的可用性归结为一个分数并不能认识到这些好处。未来视频喉镜与直接喉镜之间的可用性比较将提供有用的信息，但这不应该是评估这些设备效用的唯一方法。可用性需要在上下文中理解，包括有效性、效率和（由系统可用性量表衡量）满意度。成功率、所花费的时间和其他患者报告的措施必须仍然是评估气道装置的主要指标。