Study On The Efficacy Of Methylene Blue In The Treatment Of Refractory Septic Shock

Objective(s): To assess the efficacy of methylene blue(MB)with varying infusion rates on those with refractory septic shock.Methods: This study retrospectively analysed 137 patients with refractory septic shock who were admitted to the intensive care unit(ICU)of a class III hospital in Yunnan from April 2020 to December 2022.The patients were divided into non-MB group,slow MB group and fast MB group based on their MB use.Baseline characteristic data were collected for all patients.Before、1、3、and6 hours after the treatment,the mean arterial pressure(MAP),heart rate,norepinephrine(NE)dose,and urine volume were all recorded.Before the treatment and 6 hours after the treatment,the arterial lactic acid(Lac)was collected.Lactate clearance rate was calculated.The mortality rate over a seven-day period was ascertained and computed.MAP,heart rate,NE dosage,and urine volume were analyzed using generalized estimation equations.Single factor ANOVA test can be used for normal data,and rank sum test can be used for non normal data;The 7-day mortality rate was calculated using a chi-square test.Results: 1.No noteworthy divergence was observed in the baseline characteristics of the three patient groups:previous illness,age,number of infected sites during ICU stay stay,sex,body mass index,sequential organ failure assessment within 24 hours of ICU stay,acute physiology and chronic health evaluation scoring system II within 24 hours of ICU stay,Lac within 24 hours of ICU stay,MAP before ICU stay,and the amount of infected microorganisms during ICU stay,when compared(P>0.05).2.There was no statistical difference in MAP,heart rate,NE dosage and urine volume within 1 hour before the treatment among the three groups(P>0.05).3.The results of the generalized estimation equation show that:1)MAP:the MAP of the fast MB group was significantly different from that of the non-MB group at time point H1(P<0.05).The MAP of the slow MB group was significantly different from that of the non-MB group at H3 and H6(P<0.05).Overall,the MAP in the slow MB group was statistically different from the non-MB group[B=3.91,P=0.049,OR(95%CI)=49.81(1.01～2457.48)]。2)NE:at h6,there was a significant statistical difference between NE dosage in the slow MB group and the non-MB group(P<0.05),and between NE use in the fast MB group and the non-MB group(P<0.05).Overall NE usage in the slow MB group was statistically different from the non-MB group [B=-0.65,P=0.033,OR(95%CI)=0.52(0.29～0.95)].The fast MB group had a statistically significant difference in NE usage compared to the non-MB group [B=-0.41,P=0.042,OR(95%CI)=0.66(0.45～0.99)].3)Heart rate:statistically significant difference in heart rate between the slow MB group and the non-MB group was observed at H3(P<0.05).In the overall comparison with the non-MB group,none of the heart rates in the slow MB group were statistically significant(P>0.05),nor was the heart rate in the fast MB group.4)Urine volume:there was no statistically significant difference in urine volume between the groups at the different time points(P>0.05).4.No statistical difference was observed between the three groups in terms of lactic acid after 6 hours of the treatment,nor in terms of lactate clearance rate after 6hours of the treatment(P>0.05).5.No statistical distinction in 7-day mortality was observed between the three groups(P>0.05).Conclusion(s):In this retrospective study,MB do not appear to improve 7-day mortality.The slower continuous intravenous infusion of MB may have been more effective than the faster drip and non MB groups in elevating MAP and reducing norepinephrine usage,but it may not improve heart rate,urine output and decrease lactate more effectively,and elevate lactate clearance after 6 hours of the treatment.