Mathews Abdul-Maajid, Stein Christopher, Richter Marietjie
Department of Emergency Medical Care, Faculty of Health Sciences, University of Johannesburg, South Africa.
Department of Optometry, Faculty of Health Sciences, University of Johannesburg, South Africa.
Afr J Emerg Med. 2021 Jun;11(2):218-222. doi: 10.1016/j.afjem.2020.12.002. Epub 2021 Feb 19.
Endotracheal intubation by direct laryngoscopy is a mainstay of advanced airway management performed both in the prehospital environment and in the Emergency Department. Many factors may affect the quality of view during direct laryngoscopy, one of them being the visual acuity (VA) of the intubator under these demanding conditions. While some individual variation in VA is to be expected in younger populations, VA naturally deteriorates in older populations particularly beyond the age of 40 years. This study aimed to describe VA in a younger (=19) and an older (≥40 years of age, =20) cohort of intubators at baseline and during simulated adult laryngoscopy, and to compare VA between these two age cohorts.
A baseline near VA test was done using a Sloan Early Treatment Diabetic Retinopathy Study (EDTRS) near vision chart at 40 cm under ambient indoor light. Participants in both age cohorts were then requested to perform laryngoscopy using an airway simulator at 40 cm viewing distance and again at a viewing distance of their choice. Both binocular and monocular VA were tested using a near VA chart placed anterior to the vocal cords of the airway trainer. VA was quantified using the logarithm of the minimum angle of resolution (logMAR). Differences in VA between age cohorts were assessed using independent samples -tests and differences within age cohorts were assessed using paired samples -tests.
Binocular and monocular near VA was significantly reduced in the older cohort compared to the younger cohort at baseline (both eyes -0.129 logMAR; = 0.04, right eye -0.147 logMAR; = 0.005, left eye -0.197 logMAR; = 0.002). Within each age cohort VA was significantly reduced during laryngoscopy at a fixed viewing distance (younger; both eyes -0.111 logMAR; < 0.001, right eye -0.095 logMAR; < 0.001, left eye -0.105 logMAR; < 0.001; older; both eyes -0,08 logMAR; p < 0.001, right eye -0.110 logMAR; p < 0.001, left eye -0.065 logMAR; = 0.01) but this was improved by reducing viewing distance.
Increased age was associated with a significant reduction in VA at baseline and during laryngoscopy, which can be partially compensated for by adjusting viewing distance. Although it is currently unknown to what extent this age-related reduction of VA might negatively affect time to place an endotracheal tube or success of placement under direct vision, older intubators should be aware of this effect and consider specialized corrective eyewear in order to maintain an adequate level of VA.
直接喉镜下气管插管是院前环境和急诊科进行高级气道管理的主要方法。许多因素可能影响直接喉镜检查时的视野质量，其中之一是在这些苛刻条件下插管者的视力（VA）。虽然在较年轻人群中视力存在一些个体差异是可以预期的，但在老年人群中，尤其是40岁以上，视力自然会下降。本研究旨在描述较年轻（=19）和较年长（≥40岁，=20）两组插管者在基线时以及模拟成人喉镜检查期间的视力，并比较这两个年龄组之间的视力。
在室内环境光下，使用Sloan糖尿病视网膜病变早期治疗研究（EDTRS）近视力表在40厘米处进行基线近视力测试。然后要求两个年龄组的参与者使用气道模拟器在40厘米的观察距离以及他们选择的观察距离进行喉镜检查。使用放置在气道训练器声带前方的近视力表测试双眼和单眼视力。视力使用最小分辨角的对数（logMAR）进行量化。年龄组之间的视力差异使用独立样本检验进行评估，年龄组内的差异使用配对样本检验进行评估。
与较年轻组相比，较年长组在基线时双眼和单眼近视力显著降低（双眼-0.129 logMAR；p = 0.04，右眼-0.147 logMAR；p = 0.005，左眼-0.197 logMAR；p = 0.002）。在每个年龄组中，在固定观察距离进行喉镜检查时视力显著降低（较年轻组；双眼-0.111 logMAR；p < 0.001，右眼-0.095 logMAR；p < 0.001，左眼-0.105 logMAR；p < 0.001；较年长组；双眼-0.08 logMAR；p < 0.001，右眼-0.110 logMAR；p < 0.001，左眼-0.065 logMAR；p = 0.01），但通过缩短观察距离可有所改善。
年龄增加与基线时和喉镜检查期间视力显著降低相关，通过调整观察距离可部分补偿。虽然目前尚不清楚这种与年龄相关的视力下降在多大程度上可能对气管插管时间或直视下插管成功率产生负面影响，但年长的插管者应意识到这种影响，并考虑使用专门的矫正眼镜以维持足够的视力水平。
