The preventive effects of methoxamine pretreatment on hypotension in thoracotomy

HU Jing-li; HU Jing; JIAO Hong-mei; SHI Bin

doi:10.3969/j.issn.1001-9448.2018.09.012

Abstract：Objective To observe the preventive effects of methoxamine infused with micro -pump on hypoten-sion induced by combined extradural and general anesthesia (CEGA) in thoracotomy.Methods Under CEGA, 151 pa-tients (aged 40-65 years old, ASA Ⅰ-Ⅱ) undergoing thoracotomy were randomly divided into 3 groups, Group A (n＝52, received single dose methoxamine), Group B1 (n＝51, received methoxamine 3 μg/(kg·min) infused with micro-pump), Group B2 (n＝48, received methoxamine 4 μg/(kg·min) infused with micro -pump).Patients in Group A received a bolus methoxamine of 2 mg whenever systolic blood pressure (SBP) decreased to 80 mmHg or lower than 80%of baseline.If necessary, additional bolus of methoxamine of 1 mg was administered until the SBP recovered to (100±20)%of the baseline.After epidural puncture , patients in Group B1 and Group B2 received 3 ml of 1% Lido-caine via spinal needle and 1mg bolus of methoxamine intravenous injection .Subsequently, patients in Group B1 received methoxamine 3 μg/(kg·min) infused with micro-pump, as patients in Group B2 received methoxamine 4 μg/(kg·min) infused with micro -pump followed by intermittent 0.375% Ropivacame via spinal needle .Whenever SBP de-creased to 80 mmHg or lower than 80%of the baseline, additional a bolus of methoxamine of 1 mg was administered until the SBP recovered to (100±20)%of the baseline.Systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR) were recorded before anesthesia (T0), 5 min after ropivacaine administration (T1), 15 min after ropiva-caine administration (T2), during general anesthesia induction (T3) and at beginning of thoracotomy (T4).The time of operation, infusion quantity during operation , urine volume, bleeding volume and frequency of methoxamine required were also recorded.Results Compared with Group A, the incidence of hypotension in Group B1 and B2 were 23.53% and 8.33%, respectively, which was significantly lower (P＜0.05).There were significant differences in the frequencies of methoxamine required between Group B1 and B2 (P＜0.05).At T2 and T3, the SBP, DBP, HR in Groups A, B1 and B2 were significantly lower than those at T 0.The SBP and DBP in Group B1 and B2 were significantly higher than those in Group A (P＜0.05).At T3, the SBP and DBP in Group B2 was significantly higher than group B1 (P＜0.05).Con-clusion The usage of methoxamine has preventive effects on hypotension induced by CEGA in thoracotomy .In compari-son with irregular administration , prophylactically sustained administration provides lower incidence of hypotension and more stable blood pressure .The infusion speed of 4 μg/(kg·min) is more beneficial for hemodynamic stability .