Background

Opioids produce pupillary constriction but their impact on pupillary unrest and the dynamic parameters of the pupillary light reflex have not been characterized. Given the increasing use of portable pupillometers for care of critically ill patients, it is important to distinguish between opioid effects on the pupil versus those that have been reported to arise from traumatic and ischemic brain insults. We undertook this study to determine which pupillary responses are most profoundly and consistently affected by a progressive infusion of remifentanil.

Methods

We studied the effect of remifentanil on the pupil using two portable infrared pupillometers in 18 volunteers. One pupillometer measured pupillary unrest in ambient light (PUAL) and the other pupillometer measured neurological pupillary index (NPi), constriction velocity (CV), pupil diameter (PD), latency, and % reflex (% reflex) following a transient light flash. Remifentanil was administered at predetermined weight-adjusted rates to raise opioid effect site concentration up to a range known to produce respiratory depression and oxyhemoglobin desaturation, based on a previously published pharmacokinetic model.

Results

PUAL was ablated by remifentanil, declining 94 ± 6% from baseline at the time of maximum drug effect. Other pupillary measurements decreased 50–65% from baseline. NPi was unchanged. At the time of oxyhemoglobin desaturation, deviations in PD, CV, and % reflex were widely scattered, whereas PUAL consistently approached zero.

Conclusion

PUAL is a highly specific indicator of central opioid effect. As a non-invasive measure, it may provide useful data to clinicians who prescribe opioids.

中文翻译：

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用瞳孔测量法检测阿片类药物的作用

背景

阿片类药物会导致瞳孔收缩，但它们对瞳孔不安定的影响和瞳孔光反射的动态参数尚未得到表征。鉴于越来越多地使用便携式瞳孔计来护理危重病人，区分阿片类药物对瞳孔的影响与据报道由创伤性和缺血性脑损伤引起的影响很重要。我们进行了这项研究，以确定哪些瞳孔反应受到瑞芬太尼渐进式输注最深刻和持续的影响。

方法

我们使用两个便携式红外瞳孔计在 18 名志愿者中研究了瑞芬太尼对瞳孔的影响。一个瞳孔计测量环境光下的瞳孔不安度 (PUAL)，另一个瞳孔计测量神经学瞳孔指数 (NPi)、收缩速度 (CV)、瞳孔直径 (PD)、潜伏期和瞬态闪光后的反射百分比 (% 反射)。根据先前公布的药代动力学模型，瑞芬太尼以预先确定的体重调整率给药，以将阿片类药物效应部位浓度提高到已知会产生呼吸抑制和氧合血红蛋白去饱和的范围。

结果

PUAL 被瑞芬太尼消融，在最大药物作用时从基线下降 94 ± 6%。其他瞳孔测量值比基线下降了 50-65%。NPi 没有变化。在氧合血红蛋白去饱和时，PD、CV 和反射百分比的偏差广泛分布，而 PUAL 始终接近零。

结论

PUAL 是中枢阿片类药物作用的高度特异性指标。作为一种非侵入性措施，它可以为开阿片类药物的临床医生提供有用的数据。