Barvais L, Engelman E, Eba J M, Coussaert E, Cantraine F, Kenny G N
Department of Anaesthesia, Erasme Hospital, 808 route de Lennik, 1070 Anderlecht, Belgium.
Br J Anaesth. 2003 Sep;91(3):347-52. doi: 10.1093/bja/aeg178.
Opioid drugs block reflex pupillary dilatation in response to noxious stimulation. The relationship between the target effect site concentration (Ce(T)) of remifentanil and the pupil diameter and reactivity in response to a standard noxious stimulus were evaluated.
Anaesthesia was induced with propofol TCI to obtain loss of consciousness (LOC) in 12 ASA I/II patients. Thereafter, remifentanil Ce(T) was titrated by increments of 1 up to 5 ng ml(-1). In the awake state, at LOC and at each plateau level of remifentanil Ce(T), arterial pressure, heart rate, and BIS (A2000) were recorded. Pupil size and dilatation after a 100 Hz tetanic stimulation (T100) were measured at LOC and at each plateau level of remifentanil Ce(T).
LOC was observed at a mean propofol Ce(T) of 3.53 (SD 0.43) microg ml(-1). Arterial pressure and heart rate decreased progressively from LOC to 5 ng ml(-1) remifentanil Ce(T) without any statistical difference between each incremental dose of remifentanil. Mean BIS values decreased from 96 (2) in the awake state, to 46 (12) at LOC (P<0.05) and then remained unchanged at all remifentanil Ce(T). Pupil dilatation in response to 100 Hz tetanic stimulation decreased progressively from 1.55 (0.72) to 0.01 (0.03) mm and was more sensitive than pupil diameter measured before and after 100 Hz tetanus. An inverse correlation between pupil dilatation in response to 100 Hz tetanus and an increase in remifentanil Ce(T) from 0 to 5 ng ml(-1) was found (R(2)=0.68).
During propofol TCI in healthy patients, the decrease in pupil response to a painful stimulus is a better measurement of the progressive increase of remifentanil Ce(T) up to 5 ng ml(-1) than haemodynamic or BIS measurements.
阿片类药物可阻断因有害刺激引起的反射性瞳孔散大。本研究评估了瑞芬太尼的靶效应部位浓度（Ce(T)）与瞳孔直径以及对标准有害刺激的反应性之间的关系。
对12例美国麻醉医师协会（ASA）分级为I/II级的患者，采用丙泊酚靶控输注（TCI）诱导麻醉以使其意识消失（LOC）。此后，瑞芬太尼的Ce(T)每次递增1直至5 ng/ml进行滴定。在清醒状态、意识消失时以及瑞芬太尼Ce(T)的每个平台期水平，记录动脉压、心率和脑电双频指数（BIS，A2000）。在意识消失时以及瑞芬太尼Ce(T)的每个平台期水平，测量100 Hz强直刺激（T100）后的瞳孔大小和散大情况。
平均丙泊酚Ce(T)为3.53（标准差0.43）μg/ml时出现意识消失。从意识消失到瑞芬太尼Ce(T)达5 ng/ml，动脉压和心率逐渐下降，瑞芬太尼每次递增剂量之间无统计学差异。平均BIS值从清醒状态下的96（2）降至意识消失时的46（12）（P<0.05），此后在所有瑞芬太尼Ce(T)水平均保持不变。对100 Hz强直刺激的瞳孔散大从1.55（0.72）逐渐降至0.01（0.03）mm，且比100 Hz强直刺激前后测量的瞳孔直径更敏感。发现对100 Hz强直刺激的瞳孔散大与瑞芬太尼Ce(T)从0增至5 ng/ml呈负相关（R² = 0.68）。
在健康患者丙泊酚TCI期间，与血流动力学或BIS测量相比，瞳孔对疼痛刺激反应的降低是评估瑞芬太尼Ce(T)逐渐增加至5 ng/ml的更好指标。
