| Background Septic shock is a serious complication of an infection that occurs commonly in intensive care units.Despite the continuous improvement in critical care,the mortality of septic shock remains high.The pathophysiology of this complication meanly attribute to an insufficiency of effective circulating volume caused by infection,resulting in decreased tissue and organ perfusion.Fluid resuscitation aiming to improve tissue perfusion is one of the crucial treatments of septic shock.Dexmedetomidine is a sedative medication that has been commonly used in critical care unit.Previous studies indicated that dexmedetomidine can improve tissue perfusion in patients with septic shock.Current study addresses a further discussion based on these findings.Objective To evaluate the effects of dexmedetomidine on hemodynamics and microcirculation in patients with early septic shock.Methods(1)Study design:This was randomized,case-controlled,double-blind study based on a prospective cohort from a single unit;(2)Patients:Between February 1st,2016 and March 31st,2017 in the Southeast University Affiliated Zhongda Hospital,department of Intensive Care Unit(ICU),patients diagnosed with early-staged(<24h from onset)septic shock undergoing fluid resuscitation with an average arterial pressure of 65 mmHg were recruited into the study;(3)Settings:Patients were randomized into two groups,test group and control group,according to the random number table.Patients in test group received continuously intravenous pump of dexmedetomidine at the dose of 0.7 ug/kg/hr,Patients in the control group received continuously intravenous pump of saline at the dose of 0.7 ug/kg/hr;(4)Hemodynamics,oxygenation,and microcirculation perfusion level were measured in recruited patients.Hemodynamics was monitored by pulse-directed continuous cardiac output(PiCCO);oxygenation was measured by blood gas tests,and the microcirculation perfusion level was evaluated by SDF imaging technique.(5)Observations and data collection:The following clinical data were recorded and collected 1 hour before and 1 hour after the drug was administrated.① Hemodynamic parameters:general indicators such as heart rate(HR),etc.;pressure index,such as mean arterial pressure(MAP),central venous pressure(CVP),etc.;volume index,such as the stroke volume(SV),stroke index(SVI),cardiac output(CO),etc.;resistance index,such as Systemic vascular resistance(SVR),Systemic vascular resistance index(SVRI),etc.② Oxygenation parameters:arterial oxygen partial pressure(Pa02),arterial oxygen saturation(Sv02),venous oxygen saturation(Pv02),venous oxygen saturation(Sv02),lactic acid(Lac),etc.③ Microcirculation parameters:Total vascular density(TVD),perfused vessel density(PVD),proportion of perfused vessels(PPV),microvascular flow index(MFI),and other parameters were measured by image analysis software.(6)Test conditions:Both groups were treated with analgesia.Remifentanil,morphine and other analgesic drugs were administrated by continuously intravenous pump.The critical care Patient Observation Tool(CPOT)score 0～1 point was assessed consistently.During the study period,the infusion rate and the fluid volume of resuscitation were placed at the same level.The dose of vasoactive drugs was adjusted according to the blood pressure and maintained at mean arterial pressure of(MAP)>65mmHg.Patients’ oxygen saturation(Sp02)was maintained at 95%or more.(7)Blindness:Study medicine was randomization according to the random number table,to maintain the appearance and shape consistency.Custodians and users were both blinded to the specific content of the drug.The blindness was reviled until the complete of data collection.Results(1)Recruitment of study cohort:283 patients with septic shock were enrolled into this cohort during the study period.Thirty-seven patients were excluded due to the cerebrovascular accident;22 patients were excluded due to the abnormal liver function;79 patients were excluded because EGDT did not meet the standard;56 cases were excluded because PiCCO catheter were not placed;41 cases were excluded due to the age factors.Among the 48 patients meeting the eligibility of recruitment criteria,2 patients with significant bradycardia after the use of the drugs were suspended;7 patients reported a poor quality of microcirculation images were suspended.Eventually,39 patients were recruited for analysis,of whom 17 were placed in the control group and 22 in the test group.(2)Comparison of the two groups of patients:Of the 39 patients enrolled in the study,the mean age of the control and experimental groups was 72.5 ± 10.8 years and 71± 11.0 years,respectively(p = 0.850);gender ratio was 13/4 and 17/5,respectively(p = 0.623).In terms of the severity of the disease,there was no significant difference in APACHE II score(p = 0.092)and SOFA score(p =0.798)between the two groups.The main underlying disease was hypertension(p= 0.270),the major infection affected organ was lungs(p = 0.074),and there was no significant difference between the control group and the test group.The hemodynamic parameters of the two groups were compared.There was no significant difference between the control group and the test group in heart rate(HR),mean arterial pressure(MAP),cardiac output(CO)and other stress,resistance and capacity index(p>0.05).(3)Effects of dexmedetomidine on hemodynamics in patients with septic shock:The study medicine was continuously pumped at a rate of 0.7 ug/kg/hr for 1 hour,there was no significant difference in heart rate(HR)between the control group and the test group(94.82 bpm vs.96.86 bpm,P = 0.758),mean arterial pressure(MAP),cardiac output(CO)[(83.65 mmHg vs.81.08 mmHg,= 0.417);(6.18L/min vs.6.66L/min,P = 0.480)]and other stress,resistance.Other hemodynamic parameters were not significantly different between control group and test group.(4)Effects of dexmedetomidine on oxygen metabolism in patients with septic shock:The study medicine was continuously pumped at a rate of 0.7 ug/kg/hr for 1 hour,there were no significant diflferences in the oxygen metabolism(ScvO2)and lactic acid(Lac)between the control group and the test group(79.52%vs.75.81%,p =0.229;2.26mmol/L vs.2.50 mmol/L,p = 0.356).In the subgroup analysis of Lac≥2mmol/L,there were also no significant differences in ScvO2 and Lac(78.86%vs.76.46%,p = 0.401;3.53 mmol/L vs.4.02 mmol/L,p = 0.779).(5)Effects of dexmedetomidine on microcirculation in patients with septic shock:The study medicine was continuously pumped a rate of 0.7 ug/kg/hr for 1 hour,there was no significant difference in perfusion vascular density(PVD),microvascular flow index(MFI)between the control group and the test group(22.59 mm/mm2 vs.16.75 mm/mm2,p = 0.586;2.49 vs.2.43,p = 0.670).In the subgroup analysis of Lac≥2mmol/L,there was no significant difference in PVD and MFI between the two subgroups(10.76 mm/mm2 vs.14.27 mm/mm2,P = 0.401;2.39 vs.2.46,P = 0.889).Conclusion Dexmedetomidine had no significant effect on hemodynamics and microcirculation in patients with septic shock. |
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