BACKGROUND A CO2 pneumoperitoneum during a laparoscopic procedure causes violent hemodynamic changes. However, the remifentanil required to inhibit the cardiovascular response to a CO2 pneumoperitoneum combined with propofol remains unknown. Moreover, the sex of the patient may influence the response to opioids, which can affect this requirement. The main objective of this study was to compare the required median effective concentration (EC50) of remifentanil for inhibiting the cardiovascular response to a CO2 pneumoperitoneum between female and male patients during propofol anesthesia. METHODS The current study is an up-and-down sequential allocation trial. Forty-six patients with American Society of Anesthesiologists physical status I or II, a body mass index 18 to 30 kg/m2, aged 20 to 60 years, and scheduled for laparoscopic surgery were enrolled. Induction of anesthesia was performed by target-controlled infusion. The effective effect-site concentration (Ce) of propofol was 4 μg/ml. The Ce of remifentanil was initially 4 ng/ml and then adjusted to a predetermined level after I-gel laryngeal mask airway insertion. The Ce of remifentanil for each patient was determined by the response of the previous patient using the modified Dixon "up-and-down" method. The first patient received remifentanil at 5.0 ng/ml Ce, and the step size between patients was 0.5 ng/ml. RESULTS Patients characteristics including age, body mass index, American Society of Anesthesiologists physical status, type of surgery and surgery duration, were comparable between male and female patients. The EC50 of remifentanil required to inhibit the response to a CO2 pneumoperitoneum based on the Dixon "up-and-down" method in women (4.17 ± 0.38 ng/ml) was significantly lower than that in men (5.00 ± 0.52 ng/ml) during propofol anesthesia (P = 0.01). CONCLUSIONS The EC50 of remifentanil required to inhibit the response to a CO2 pneumoperitoneum was lower in women than in men during propofol anesthesia. TRIAL REGISTRATION The study was registered at http://www.chictr.org.cn (ChiCTR-IOR-17011906, 8th, July, 2017).

中文翻译：

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性别差异对瑞芬太尼抑制丙泊酚麻醉期间对CO2气腹反应的要求的影响：上下连续试验。

背景技术在腹腔镜手术期间的CO 2气腹会引起剧烈的血液动力学变化。但是，抑制瑞芬太尼与丙泊酚联合使用对抑制CO2气腹的心血管反应所需的药物仍然未知。此外，患者的性别可能会影响对阿片类药物的反应，从而影响这一需求。这项研究的主要目的是比较丙泊酚麻醉期间男女使用瑞芬太尼抑制女性对男性对CO2气腹的心血管反应所需的中位数有效浓度（EC50）。方法目前的研究是上下连续分配试验。46位美国麻醉师学会I或II身体状况患者，体重指数18至30 kg / m2，年龄20至60岁，并预定进行腹腔镜手术。麻醉的诱导是通过靶控输注进行的。异丙酚的有效作用部位浓度（Ce）为4μg/ ml。瑞芬太尼的Ce最初为4 ng / ml，然后在插入I-gel喉罩气道后调整至预定水平。使用改良的Dixon“上下法”，通过先前患者的反应确定瑞芬太尼的Ce值。首例患者接受了5.0 ng / ml Ce的瑞芬太尼，患者之间的步调为0.5 ng / ml。结果患者特征包括年龄，体重指数，美国麻醉医师学会的身体状况，手术类型和手术持续时间在男女患者之间是可比的。女性（4.17±0.38 ng / ml）根据狄克逊“上下法”抑制瑞芬太尼对EC2气腹产生的抑制作用的EC50显着低于男性（5.00±0.52 ng / ml）异丙酚麻醉期间（P = 0.01）。结论丙泊酚麻醉期间，抑制瑞芬太尼对CO2气腹的反应所需的EC50低于男性。试验注册本研究已在http://www.chictr.org.cn注册（ChiCTR-IOR-17011906，2017年7月8日）。结论丙泊酚麻醉期间，抑制瑞芬太尼对CO2气腹的反应所需的EC50低于男性。试验注册本研究已在http://www.chictr.org.cn注册（ChiCTR-IOR-17011906，2017年7月8日）。结论丙泊酚麻醉期间，抑制瑞芬太尼对CO2气腹的反应所需的EC50低于男性。试验注册本研究已在http://www.chictr.org.cn注册（ChiCTR-IOR-17011906，2017年7月8日）。