Department of Anesthesia and Perioperative Care, University of California, 521 Parnassus Avenue, #4307, San Francisco, CA, 94117, USA.
Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco, CA, USA.
Can J Anaesth. 2024 May;71(5):611-618. doi: 10.1007/s12630-024-02716-2. Epub 2024 Mar 19.
The pupil displays chaotic oscillations, also referred to as pupillary unrest in ambient light (PUAL). As pain has previously been shown to increase pupillary unrest, the quantitative assessment of PUAL has been considered a possible tool to identify and quantify pain. Nevertheless, PUAL is affected by various states, such as vigilance, cognitive load, or emotional arousal, independent of pain. Furthermore, systematically applied opioids are known to reduce PUAL, thus potentially limiting its usefulness to detect pain or changes in pain intensity. To test the hypothesis that PUAL can reliably identify changes in pain intensity in a clinical setting, we measured PUAL in patients experiencing substantial pain relief when regional anesthesia interventions were applied after surgery.
We conducted an observational study at an academic surgery centre following institutional review board approval. Eighteen patients with unsatisfactory pain control following surgery underwent regional anesthesia procedures to improve pain control. We used infrared pupillometry to assess pupillary unrest before and after the regional block. We then compared the changes in pupillary unrest with the changes in pain scores (numeric rating scale [NRS], range 0-10).
Eighteen patients received epidural anesthesia (n = 14) or peripheral nerve blocks (n = 4), resulting in improvement of mean (standard deviation [SD]) NRS pain scores from 7.2 (1.7) to 1.9 (1.8) (difference in means, -2.2; 95% confidence interval [CI], -6.3 to -4.1; P < 0.001). Nevertheless, pupillary unrest did not change as pain decreased; the mean (SD) PUAL was 0.113 (0.062) before analgesia and 0.112 (0.068) after analgesia (difference in means, -0.001; 95% CI, -0.018 to 0.015; P = 0.88).
In this prospective observational study, pupillometric measurements of pupillary unrest did not identify changes in pain intensity in a postoperative, predominantly opioid-exposed patient population. While the sample size was small, the use of measurements of pupillary unrest to detect and quantify pain has to be questioned.
瞳孔呈现出混沌的波动，也被称为在环境光下的瞳孔不安（PUAL）。因为疼痛已被证明会增加瞳孔不安，所以对 PUAL 的定量评估被认为是一种识别和量化疼痛的可能工具。然而，PUAL 会受到各种状态的影响，例如警觉性、认知负荷或情绪唤醒，而与疼痛无关。此外，系统应用阿片类药物已知会降低 PUAL，从而可能限制其用于检测疼痛或疼痛强度变化的用途。为了测试 PUAL 能否可靠地识别临床环境中疼痛强度变化的假设，我们在手术后进行区域麻醉干预时经历了明显疼痛缓解的患者中测量了 PUAL。
我们在机构审查委员会批准后，在一家学术外科中心进行了一项观察性研究。18 名手术后疼痛控制不满意的患者接受了区域麻醉程序以改善疼痛控制。我们使用红外瞳孔测量法在区域阻滞前后评估瞳孔不安。然后，我们将瞳孔不安的变化与疼痛评分的变化（数字评分量表[NRS]，范围 0-10）进行比较。
18 名患者接受了硬膜外麻醉（n=14）或外周神经阻滞（n=4），导致 NRS 疼痛评分从 7.2（1.7）平均（标准差[SD]）改善至 1.9（1.8）（平均差异，-2.2；95%置信区间[CI]，-6.3 至-4.1；P<0.001）。然而，随着疼痛的减轻，瞳孔不安并没有改变；镇痛前的平均（SD）PUAL 为 0.113（0.062），镇痛后为 0.112（0.068）（平均差异，-0.001；95%CI，-0.018 至 0.015；P=0.88）。
在这项前瞻性观察性研究中，瞳孔不安的瞳孔测量法未能识别出术后以阿片类药物为主的患者人群中疼痛强度的变化。虽然样本量较小，但使用瞳孔不安测量来检测和量化疼痛的方法值得质疑。
