Prophylactic Administration with Methylene Blue Improves Hemodynamic Stabilization During Obstructive Jaundice–Related Diseases’ Operation: a Blinded Randomized Controlled Trial

Objectives
 Patients with obstruction jaundice are at a high risk of hypotension and need high volume of fluids and a high dose of catecholamine to maintain organ perfusion during operation procedure. All these likely contribute to high perioperative morbidity and mortality. The aim of the study is to evaluate the effects of methylene blue on the hemodynamics in patients undergoing surgeries associated with obstructive jaundice. Design A prospective, randomized, and controlled clinical study. Setting The enrolled patients randomly received 2 mg/kg of methylene blue in saline or saline (50 ml) before anesthesia induction. The primary outcome was the frequency and dose of noradrenaline administration to maintain mean arterial blood pressure over 65 mmHg or > 80% of baseline, and systemic vascular resistance (SVR) over 800 dyne/s/cm5 during operation. The secondary outcomes were liver and kidney functions, and ICU stay. Patients Seventy patients were enrolled in the study and randomly assigned to receive either methylene blue or control (n = 35/group). Results Fewer patients received noradrenaline in the methylene blue group when compared with the control group (13/35 vs 23/35, P = 0.017), and the noradrenaline dose administrated during operation was reduced in the methylene blue group when compared with the control group (0.32 ± 0.57 mg vs 1.787 ± 3.51 mg, P = 0.018). The blood level of creatinine, glutamic oxalacetic transaminase, and glutamic–pyruvic transaminase after the operation was reduced in the methylene blue group when compared with the control group. Conclusions Prophylactic administration of methylene blue before operation associated with obstructive jaundice improves hemodynamic stability and short-term prognosis. Question Methylene blue use prevented refractory hypotension during cardiac surgery, sepsis, or anaphylactic shock. It is still unknown that methylene blue on the vascular hypo-tone associated with obstructive jaundice. Findings Prophylactic administration with methylene blue improved peri-operative hemodynamic stability, and hepatic and kidney function on the patients with obstructive jaundice. Meanings Methylene blue is a promising and recommended drug for the patients undergoing the surgeries of relief obstructive jaundice during peri-operation management. Supplementary Information The online version contains supplementary material available at 10.1007/s11605-022-05499-3.


Background
2][3][4][5] Surgical interventions to relieve obstructive jaundice are essential but are often associated with a high postoperative morbidity and mortality.It has been reported that improved preoperative preparation and peri-operation management may greatly contribute to a favorable outcome, but those are not optimized yet.Patients with obstructive jaundice often presented to be hypotensive after anesthesia induction and are at a high risk of severe hypotension.Thus, the patients often need a large volume of fluid loading and a large dose of vasopressors to maintain adequate blood pressure. 6,7][10] Methylene blue is the second-line drug to treat this refractory hypotension; however, it was found that methylene blue improved the hemodynamics in the critical ill patients with refractory hypotension, and the patients may benefit more from early than later administration. 11To date, it remains unknown whether the patients with obstructive jaundice are also benefited from prophylactic administration of methylene blue.The patients, who were scheduled to undergo surgeries for relieving obstructive jaundice, were enrolled to evaluate the effects of prophylactic administration of methylene blue on the hemodynamic status and organs' function in this trial.

Ethics
This study protocol was approved by the Institutional Review Board of Southwest Hospital, Third Military Medical University (No. 2016(94)), and registered on the clinical trial registration website (www.chictr.org.cn; Number: ChiCTR-IOR-16,010,206) on 21 December 2016.Procedures were followed by the ethical standards of the committee on human experimentation and with the Helsinki Declaration of 1975.Written informed consent was obtained from all of the enrolled patients.All authors had access to the study data and had reviewed and approved the final manuscript.

Patients' Recruitment
Patients with obstructive jaundice as indicated as TBIL > 5.0 mg/ml and the yellowing of skin or sclera, aged between 18 and 70 years old, who need surgical intervention, were enrolled in this study (Fig. 1) from January 15, 2017, to June 17, 2018, at Southwest hospital, the Third Military Medical University, Chongqing, China.Patients were excluded if they met any of the following criteria: anesthesiologists (ASA) physical status scores IV and V, the patients received selective serotonin reuptake inhibitor (SSRI) therapy, abdominal surgery history, coronary heart disease, hypertension, and any other cardiovascular diseases to be treated with medication, respiratory dysfunction including P a O 2 ≤ 60 (F i O 2 > 21%) or/and PaCO 2 ≥ 50 mmHg, undergoing other clinical studies within recent 3 months or refusal to participate the study.The indications and operations performed for these patients are shown in the Supplemental Table 1 and Supplemental Table 2.

Randomization
Randomization in a 1:1 ratio was done by an independent staff and all recruited patients were randomly allocated to receive either 2 mg/kg of Methylene blue I.V. in 50 ml of saline solution or 50 ml of saline solution.The researchers who collected data were blinded to the trial protocol, and the anesthesiologists who performed the anesthesia were blinded for grouping.

Procedures
The dose of 2 mg/kg of the bodyweight of methylene blue (20 mg/2 ml) (Jichuan Medicine Co., Ltd, Taixing, China) was diluted with saline solution to be 50 ml; the placebo was 50 ml of saline solution.Both were prepared by a medical staff who did not participate in the rest study.Before general anesthesia induction, all patients received placement of a central venous catheter (B.Braun, Melsongen, Germany) and Swan-Ganz catheter via the right jugular vein, and an arterial catheter (18G) at the site of the left radial artery under local anesthesia.Invasive arterial blood pressure (ABP) and central venous pressure (CVP) were monitored continuously during operation.The surgical procedures were well matched between the two groups.
The methylene blue solution or normal saline was administrated by a continuous intravenous infusion at a rate of 2.5 ml/ min before anesthesia induction, and then all the patients were induced with the administration of midazolam (0.02-0.05 mg/ kg), sufentanil (0.5-1 μg/kg), etomidate (0.2-0.3 mg/kg), and cisatracurium (0.2-0.3 mg/kg).The patients received trachea intubation and ventilated with 8-10 ml/kg of tidal volume, 12-16 rpm, 1:2 of I:E to maintain E t CO 2 between 35 and 40 cmH 2 O. Sevoflurane (1-2%) and continuous intravenous infusion of remifentanil at dose of 2-4 ng/ml of plasma concentration were administrated to maintain enough depth of anesthesia (40-60 of Bispectral Index (BIS)) throughout the surgical procedure.Cisatracurium (a bolus dose of 0.1-0.2mg/kg) was injected when necessary to keep a single or zero twitch on the train-of-four stimulation of the ulnar nerve (TOF-Watch SX; Organon Ltd., Dublin, Ireland) during operation.The anesthesia protocol was identified for all patients.Arterial blood gas analysis was determined before and after anesthesia induction, after removal of the tumor, during the phase of entero-anastomosis or choledochojejunostomy, before closure of enterocele, and 24 h after the surgery completion.Hemodynamic status and blood transfusion was managed according to the Infusion Regimen (Supplemental Tables 3 and 4).Decisions regarding all other aspects of medical care during the intraoperative and postoperative periods, including pain management after operation, and administration of fluids and antibiotics, were made by attending surgeons according the routine clinical practices.

Outcomes
The primary outcome was the frequency of norepinephrine administration during the operation phase.Secondary outcomes included the dose of norepinephrine, other vasoactive agent usage, the loading volume of fluid, liver and renal function, ICU stay, and hospital stay.

Power Calculation and Statistical Analysis
Normally distributed data are reported as mean ± standard deviation, and abnormally distributed data are reported as medians and interquartile ranges.The D'Agostino-Pearson test was applied to assess data normality.Normally distributed variables were compared using the Student t test or paired Student t-test, as appropriate, and abnormally distributed data were compared by using the Mann-Whitney test.Categorical variables were compared using Fisher's exact.(SPSS 20.0 software, Chicago, IL, USA).A P-value less than 0.05 was considered to be of statistical significance.
The frequency of noradrenaline administration to maintain mean blood pressure above 65 mmHg or > 80% of baseline during operation was about 70% in this comparable patient population in the previous study.If the frequency of noradrenaline administration during operation was reduced by half with the administration of methylene blue, then with a significance set at 0.05 and power set at 80%, the sample size required to detect differences was 66 patients in total for two arms.Taking into account a lost-to-follow-up rate of about 10%, 70 patients were enrolled.

Results
Between January 15, 2017, and June 17, 2018, 229 patients were screened for study participation.Of those, 70 patients who met recruitment criteria were recruited and randomly assigned to receive either methylene blue or control (n = 35/group) (Fig. 1).During the study period, there were no lapses in the blinding.All patients were included for data analysis.The final visit of the last randomized patient was done on September 20, 2019.Overall, the patients in the control and methylene blue group were well matched for the baseline characteristics (Table 1).

Hemodynamic Parameters During Operation
The baseline of SBP, MAP, SVR, and CO did not differ between the two groups.After anesthesia induction, SBP, MAP, and SVR were reduced in both groups.SBP (Fig. 3A) and MAP (Fig. 3B) were higher in the methylene blue group compared with the control group throughout the surgical procedure (P < 0.05).SVR was also higher in the methylene blue group compared with the control group until 180 min after anesthesia induction (P < 0.05) (Fig. 3C).CO was higher in the control group than the methylene blue group at 15 min after anesthesia induction (P < 0.05) and it was also higher in the control group than in the methylene blue group at other time points, but there was no significant difference (P > 0.05) (Fig. 3D).

The Other Anesthesia Managements During the Operation
Less patients received plasma transfusion in the methylene blue group compared with the control group (10/35 vs 19/35, P = 0.029).The frequency of plasma infusion was reduced in

Arterial Blood Gas Analysis
There was no significant difference of pH, Hb, PO 2 , PCO 2 , K + , Ca 2+ , BE, and lactic acid between the two groups at all the observed time points (Supplemental Table 5).
Other laboratory measurements did not differ between the two groups (Supplemental Table 6).

Discussion
The current study suggests that prophylactic administration of methylene blue helps to maintain hemodynamic stabilization during procedures of relieving obstructive jaundice and thus improves renal and hepatic function, attenuating cardiac ischemic injury the after the operation, and shortened the ICU stay.Patients with obstructive jaundice are at high risk for impairment of cardiovascular and low vascular response under anesthesia conditions and often need high dose of vasopressors to maintain stabilization of hemodynamic.9][20] Nitric oxide (NO) was found to be increased in the patients with obstructive jaundice and played important roles in the vascular hypo-response and organs' dysfunction in the patients with obstructive jaundice. 21n clinic practice, noradrenaline is a first-line drug to correct hypotension associated with reduced SVR 15,22 ; however, this hypotension associated with obstructive jaundice does not often respond well to norepinephrine, and hence, a large dose of norepinephrine is often administrated to combat hypotension.It was found that microcirculatory is still abnormal despite normalization of blood pressure by vasopressors under this condition, which is considered the primary cause of kidney and hepatic dysfunction, and cardiac injury after the operations. 23ethylene blue has been suggested as an adjuvant treatment in the setting of refractory hypotension. 24,25Methylene blue reduces nitric oxide-mediated vasodilation via direct inhibitory of iNOS and soluble guanylate cyclase, 26 which attenuates remarkably low response to vasoconstrictor.Methylene blue is recommended as an effective treatment of refractory hypotension which is not sensitive to catecholamine in the international guidelines. 27Recently, it has been reported that methylene blue improved both macro-circulation and micro-circulation, and thus attenuates mismatch between macro-circulation and micro-circulation induced by administration with high dose of catecholamine, 23 which was regarded to contribute to improve hepatic and kidney function, and attenuated myocardium ischemic damage.It has been reported that methylene blue is routinely administrated as rescue therapy for catecholamine-refractory hypotension in the setting of cardiac surgery, sepsis shock, and liver transplantation.Moreover, it has been found that early administration is more effective than later administration in these reports. 11,22To our best knowledge, this clinical study firstly reported the protective effect of prophylactic administration of methylene blue in patients with obstruction jaundice.Prophylactic administration of methylene blue prevented occurrence of refractory hypotension during the operation and thus protected the patients from hepatic, kidney, and cardiac injury.These data suggest that the patients with obstructive jaundice benefit from prophylactic administration of methylene blue.Some limitations of this study are the following.Firstly, this is single-center study with small sample size.Second, methylene blue was administrated before anesthesia induction; the risk and benefit of the patients with low risk of refractory hypotension remain unknown.Thirdly, the effects of methylene blue on longterm outcomes are also unknown and warrant further study.Fourthly, methylene blue may interfere some measurements, including pulse oximetry reading and alter the color of body fluid, such as urine; all these need to be closely monitored using its use and more cautions are needed to take.Lastly, some of the patients underwent pre-operation ERCP in both groups, because the number of patients who received pre-operation ERCP was not big enough to stratified analyze the effects of methylene blue and pre-operation ERCP.
Although owing to mentioned limitations, methylene blue may be recommended to be used to improve hemodynamic stabilization during operation and organ' function in the patients undergoing operations relieving obstructive jaundice, but further clinical study is still needed to verify its long-term benefits.

Conclusion
This study shows that prophylactic administration of methylene blue improves hemodynamic stabilization, and organs' function via maintaining tissue perfusion in the patients undergoing the procedures of relieving obstructive jaundice.Patients with high risk of refractory hypotension may benefit from prophylactic administration of methylene blue but warrant further study.

Fig. 2
Fig. 2 Noradrenaline (NE) usage and ICU stay.A Noradrenaline usage during operation , B duration of NE administration, C duration of ICU stay.Data are presented as dot plots and mean ± S.E.M (n = 35)

Fig. 3
Fig. 3 Hemodynamic parameters during operation.A SBP, B MAP, C SVR, and D CO during operation.Data are presented as dot plots and mean ± S.E.M (n = 35)

Table 1
Demographic characteristics and intra-operative details

Table 3
Biochemical indexes of kidney and liver function