Prevention And Treatment Of Hypotension After Spinal Anesthesia In Elderly Patients With Hypertension By Prophylactic Methoxamine Infusions

Objective:The problem of Hypotension caused by spinal anesthesia in elderly hypertensive patients undergoing PFNA surgery,this subject is based on the use of?1-adrenergic receptor agonists in the treatment of intraoperative hypotension under clinical at a suitable volumetric load,volumetric load.To investigate the clinical efficacy and safety of different dosage regimens of methoxamine in the prevention and treatment of hypotension after spinal anesthesia in elderly hypertensive patients,in order to maintain stable intraoperative hemodynamics,reduce related complications,and safely pass the perioperative period.Which to provide a reference for clinical anesthesia work.Methods:We selected 60 patients underwent PFNA surgery in our hospital,aged 65-85 years old,with a body mass index of 18.5-25.0 kg/m²,and ASA grade II-III.They regularly took anti-hypertensive drugs recommended by the World Health Organization and had good blood pressure control.The patients were randomly divided into three groups:group A?control group?:Do not pre-treatment before spinal anesthesia;group B?single pre-administration group?:Intravenous injection of methoxamine 2mg at the same time as spinal anesthesia simultaneous injection;group C?Continuous pumping group after preloading?:At the same time as spinal anesthesia,injected the loading dose of methoxyamine 1mg,then continued to pump methoxamine 1.5?g·kg^-1·min^-1.Preoperative routine ban diet befor surgery,no preoperative medication.Appropriate blood volume is added before entering the operating room.After entering the room the blood pressure,electrocardiogram and pulse oxygen saturation?SpO₂?were monitored,inhalated oxygen 3-5 L/min by the mask.Maintained fluid infusion.The invasive arterial pressure was monitored by radial artery puncture under local anesthesia.Record blood pressure every 2 minutes for 10 minutes after entering the room,The baseline level of blood pressure is the average of three consecutive measurements of blood pressure.Dilute10mg of methoxyxan to 20ml.The fractured limb lied on the upper side.After the cerebrospinal fluid has flowed out,and the drug was slowly injected.Inject light weight Ropivacaine?1.5 ml of water for injection+1.5 ml of ropivacaine?2.5 to 3.0 mL?adjust the dose according to the height?.Measuring the height of spinal anesthesia after 5-10minutes and adjust the anesthesia plane below T10.Group A:No pretreatment;Group B:Intravenous injection of methoxamine 2mg at the same time as spinal anesthesia simultaneous injection;Group C:At the same time as spinal anesthesia,injected the loading dose of methoxyamine 1mg,then continued to pump methoxamine1.5?g·kg^-1·min^-1.Three groups of MAP and HR were observed.When the MAP decreased by>20%of the baseline,the therapeutic methoxamine 1 mg was given.When there was still hypotension after 2 min,methoxamine 1 mg was again injected.Then remove the case if there is no response.In group C,the pumping rate was increased by 0.5?g·kg^-1·min^-1after the therapeutic methoxamine,and the MAP was maintained at the?100±20?%of baseline.When hypertension occurred?blood pressure increased more than 20%?stop pumping.If heart rate slowed down to 50 beats/min for 1 min,then atropine 0.5 mg was injected.The ST segment change was defined as the reversible uplift by 2 mm or a depression of 1 mm for more than 1 min.Record 10 min?T₀?after entering the operating room,3 min?T₁?,5 min?T₂?,10 min?T₃?,20 min?T₄?,30 min?T₅?after spinal anesthesia.Mean arterial pressure,heart rate,therapeutic doses of methoxamine in each group during the observation period,infusion volume of preoperative and intraoperative,hypertension,bradycardia,ST abnormalities and other adverse events.Results:There was no significant difference in general data between the three groups.Compared with T_0,in group A,MAP decreased at T₂-T₅,and HR increased at T₁-T₅;in group B,MAP increased at T₁ and decreased at T₃-T₅,HR decreased at T₂;in group C,MAP decreased at T₃ and T₄.Compared with group A,MAP increased and HR decreased at T₂-T₅ in group B and C;MAP in group B was higher than that in other groups at T₁,HR is lower than the other two groups.The incidence of hypotension in group A was higher than that in group B and C.There was no significant difference between group B and C.Compared with group A,the incidence of hypotension was significantly lower in group B and group C,and there was no significant difference between group B and group C.Compared with group A,the frequency of therapeutic of methoxamine was lower in group B and group C,There was no significant difference in the incidence of hypotension between group B and group C.Conclusion:Under appropriate blood volume load,prophylactic intravenous methoxamine can prevent hypotension after spinal anesthesia in elderly hypertensive patients undergoing PFNA surgery.And at the same time as spinal anesthesia,injecting the load dose of methoxyamine 1mg,then continuing to pump methoxamine 1.5-2.5?g·kg^-1·min^-1that can better maintain the stability of intraoperative hemodynamics and is worthy of clinical promotion.