Clinical utility of midodrine and methylene blue as catecholamine-sparing agents in intensive care unit patients with shock

Oral midodrine for prophylaxis against post-spinal anesthesia hypotension during hip arthroplasty in elderly population: a randomized controlled trial

BACKGROUND

We aimed to evaluate the efficacy of midodrine as a prophylaxis against post-spinal hypotension in elderly patients undergoing hip arthroplasty.

METHODS

This randomized controlled trial included elderly patients undergoing hip arthroplasty under spinal anesthesia. Ninety minutes before the procedure, patients were randomized to receive either 5-mg midodrine or placebo (metoclopramide). After spinal anesthesia, mean arterial pressure (MAP) and heart rate were monitored every 2 min for 20 min then every 5 min until the end of the procedure. Post-spinal hypotension (MAP < 80% baseline) was treated with 10 mg ephedrine. The primary outcome was intraoperative ephedrine consumption. Secondary outcomes were the incidence of post-spinal hypotension, bradycardia, and hypertension (MAP increased by > 20% of the baseline reading).

RESULTS

We analyzed 29 patients in the midodrine group and 27 in the control group. The intraoperative ephedrine consumption was lower in the midodrine group than in the control group (median [quartiles]: 10 [0, 30] mg versus 30 [20, 43] mg, respectively, P-value: 0.002); and the incidence of intraoperative hypotension was lower in the midodrine group than that in the control group. The incidence of hypertension and bradycardia were comparable between the two groups.

CONCLUSION

The use of 5 mg oral midodrine decreased the vasopressor requirements and incidence of hypotension after spinal anesthesia for hip surgery in elderly patients.

CLINICAL TRIAL REGISTRATION

This study was registered on September 22, 2022 at clinicaltrials.gov registry, NCT05548985, URL: https://classic.

CLINICALTRIALS

gov/ct2/show/NCT05548985 .

Study of complexation of single-stranded poly(rA) and poly(rU) with methylene blue

To reveal the effect of DNA- or RNA-specific low-molecular compounds on cellular processes on the molecular level, we have carried out the studies with the application of spectroscopic methods. It is necessary for the understanding of structural-functional properties of nucleic acids in cell. In this work the interaction of DNA-specific thiazine dye methylene blue (MB) with synthetic polynucleotides poly(rA) and poly(rU) was studied. The interaction of MB with synthetic polyribonucleotides poly(rA) and poly(rU) was examined in the solution with high ionic strength in a wide phosphate-to-dye (P/D) range, using the absorption and fluorescence spectroscopies, as well as the fluorescence 2D spectra and 3D spectra analyses were given. Values of the fluorescence quenching constants for the complexes of MB with poly(rA) and poly(rU) were calculated (KSV is the Stern-Volmer quenching constant). Two different modes of MB binding to single-stranded (ss-) poly(rA) and poly(rU) and to their hybrid double-stranded (ds-) structure - poly(rA)-poly(rU) were identified. This ligand binds to ss-poly(rA) and poly(rA)-poly(rU) by semi-intercalation and electrostatic modes, but to ss-poly(rU) the prevailing mode is the electrostatic interaction.Communicated by Ramaswamy H. Sarma.

The Use of Midodrine as an Adjunctive Therapy to Liberate Patients from Intravenous Vasopressors: A Systematic Review and Meta-analysis of Randomized Controlled Studies

BACKGROUND

Studies evaluating the role of midodrine as an adjunctive therapy to liberate patients with shock from intravenous (IV) vasopressors have yielded mixed results. The aim of our study was to evaluate the efficacy and safety of midodrine as an adjunctive therapy to liberate patients with shock from IV vasopressors.

METHODS

Electronic searches of the MEDLINE, EMBASE, and Cochrane databases through April 2022 for randomized controlled trials (RCTs) that evaluated the use of midodrine versus control in patients with shock and a low dose of IV vasopressors. The primary outcome was total IV vasopressor time, while the secondary outcomes included time-to-IV vasopressor discontinuation, IV vasopressor restart, intensive care unit (ICU) length of stay (LOS), hospital LOS, and incidence of bradycardia.

RESULTS

The final analysis included four RCTs with a total of 314 patients: 158 in the midodrine group and 156 in the control group, with a weighted mean age of 64 years (54.2% men). There was no significant difference in the total IV vasopressor time between the midodrine and control groups (standardized mean difference [SMD] - 0.53; 95% confidence interval [CI] - 1.38 to 0.32, p = 0.22; I² = 92%). Also, there were no significant differences between the two groups in the time-to-IV vasopressor discontinuation (SMD - 0.05; 95% CI - 0.57 to 0.47, p = 0.09), IV vasopressor restart (19.3 vs. 28.3%; risk ratio [RR] 0.74; 95% 0.25-2.20, p = 0.59), ICU LOS (SMD - 0.49; 95% CI - 1.30 to 0.33, p = 0.24), and hospital LOS (SMD 0.01; 95% CI - 0.27 to 0.29, p = 0.92). However, compared with the control group, the midodrine group had a higher risk of bradycardia (15.3 vs. 2.1% RR 5.56; 95% CI 1.54-20.05, p = 0.01).

CONCLUSIONS

Among patients with vasopressor-dependent shock, midodrine was not associated with early liberation of vasopressor support or shorter ICU or hospital length of stay. Adding midodrine increased the risk of bradycardia. Further large RCTs are needed to better evaluate the efficacy and safety of midodrine in liberating patients from IV vasopressors.

Effect of methylene blue on hemodynamic response in the early phase of septic shock: A case series

RATIONALE

Methylene blue (MB) has been used to increase blood pressure in septic shock, acting on the activity of guanylate cyclase and nitric oxide synthase.

PATIENCE CONCERNS

The aim of this study is to demonstrate the benefit of MB in early phase of septic shock.Diagnoses: We report 6 cases of patients with septic shock with up to 72 hours of evolution.

INTERVENTIONS

We used MB after fluid replacement, use of norepinephrine and vasopressin. Patients received a loading dose of MB and maintenance for 48 hours.

OUTCOMES

All patients presented a reduction in the dose of vasopressors and lactate levels soon after the administration of the loading dose of MB, an effect that was maintained with the maintenance dose for 48 hours. Interleukin 6 and interleukin 8 were elevated at the beginning of the septic condition, with a progressive and marked reduction after the beginning of MB infusion, demonstrating a role of MB in reducing the inflammatory activity.

LESSONS

This case series suggests that MB used early in the treatment of septic shock may be useful in reducing vasopressor dose and lactate levels. Further studies are still required to further validate these findings.

Multimodal strategy to counteract vasodilation in septic shock

Early initiation of a multimodal treatment strategy in the management of vasopressors during septic shock has been advocated to reduce delays in restoring adequate organ perfusion and to mitigate side effects associated with the administration of high-dose catecholamines. We provide a review that summarises the pathophysiology of vasodilation, the physiologic response to the vascular response, and the different drugs used in this situation, focusing on the need to combine early different vasopressors. Fluid loading being insufficient for counteracting vasoplegia, norepinephrine is usually the first-line vasopressor used to restore hemodynamics. Norepinephrine sparing is discussed in further detail through the concomitant use of adrenergic, vasopressinergic, and renin-angiotensin systems and the optimisation of endothelial reactivity with methylene blue. A blueprint for the construction of new studies is outlined to address the question of vasopressor selection and timing in septic shock.

Efficacy and safety of methylene blue in patients with vasodilatory shock: A systematic review and meta-analysis

Background

The role of methylene blue (MB) in patients with vasodilatory shock is unclear. The purpose of this systematic review and meta-analysis was to evaluate the efficacy and safety of MB in patients with vasodilatory shock.

Methods

We searched MEDLINE at PubMed, Embase, Web of Science, Cochrane, CNKI, CBM and Wanfang Medical databases for all observational and intervention studies comparing the effect of MB vs. control in vasodilatory shock patients. This study was performed in accordance with the PRISMA statement. There were no language restrictions for inclusion.

Results

A total of 15 studies with 832 patients were included. Pooled data demonstrated that administration of MB along with vasopressors significantly reduced mortality [odds ratio (OR) 0.54, 95% confidence interval (CI) 0.34 to 0.85, P = 0.008; I 2 = 7%]. This benefit in mortality rate was also seen in a subgroup analysis including randomized controlled trials and quasi-randomized controlled trials. In addition, the vasopressor requirement was reduced in the MB group [mean difference (MD) -0.77, 95%CI -1.26 to -0.28, P = 0.002; I 2 = 80%]. Regarding hemodynamics, MB increased the mean arterial pressure, heart rate and peripheral vascular resistance. In respect to organ function, MB was associated with a lower incidence of renal failure, while in regards to oxygen metabolism, it was linked to reduced lactate levels. MB had no effect on the other outcomes and no serious side effects.

Conclusions

Concomitant administration of MB and vasopressors improved hemodynamics, decreased vasopressor requirements, reduced lactate levels, and improved survival in patients with vasodilatory shock. However, further studies are required to confirm these findings.

Systematic review registration

Identifier: CRD42021281847.

Methylene blue for vasodilatory shock in the intensive care unit: a retrospective, observational study

Background

Refractory vasodilatory shock is a state of uncontrolled vasodilation associated with underlying inflammation and endothelial dysregulation. Rescue therapy for vasoplegia refractory to catecholamines includes methylene blue (MB) which restores vascular tone. We hypothesized that (1) at least 40% of critically ill patients would respond positively to MB administration and (2) that those who responded to MB would have a survival benefit.

Methods

This study was a retrospective review that included all adult patients admitted to an intensive care unit treated with MB for the indication of refractory vasodilatory shock. Responders to MB were identified as those with a ≥ 10% increase in mean arterial pressure (MAP) within the first 1-2 hours after administration. We examined the association of mortality to the groups of responders versus non-responders to MB. A subgroup analysis in patients undergoing continuous renal replacement therapy (CRRT) was also performed.

Statistical calculations were performed in Microsoft Excel® (Redmond, WA, USA). Where appropriate, the comparison of averages and standard deviations of demographics, dosing, MAP, and reductions in vasopressor dosing were performed via Chi squared, Fisher's exact test, or two-tailed t-test with a p-value < 0.05 being considered as statistically significant. After using the F-test to assess for differences in variance, the proper two tailed t-test was used to compare SOFA scores among responders versus non-responders.

Results

A total of 223 patients were included in the responder analysis; 88 (39.5%) had a ≥ 10% increase in MAP post-MB administration that was not associated with a significant change in norepinephrine requirements between responders versus non-responders (p=0.41). There was a non-statistically significant trend (21.6% vs 14.8%, p=0.19) toward improved survival to hospital discharge in the MB responder group compared to the non-responder group. In 70 patients undergoing CRRT, there were 33 responders who were more likely to survive than those who were not (p = 0.0111).

Conclusions

In patients with refractory shock receiving MB, there is a non-statistically significant trend toward improved outcomes in responders based on a MAP increase >10%. Patients supported with CRRT who were identified as responders had decreased ICU mortality compared to non-responders.

Alternatives to norepinephrine in septic shock: Which agents and when?

Vasopressors are the cornerstone of hemodynamic management in patients with septic shock. Norepinephrine is currently recommended as the first-line vasopressor in these patients. In addition to norepinephrine, there are many other potent vasopressors with specific properties and/or advantages that act on vessels through different pathways after activation of specific receptors; these could be of interest in patients with septic shock. Dopamine is no longer recommended in patients with septic shock because its use is associated with a higher rate of cardiac arrhythmias without any benefit in terms of mortality or organ dysfunction. Epinephrine is currently considered as a second-line vasopressor therapy, because of the higher rate of associated metabolic and cardiac adverse effects compared with norepinephrine; however, it may be considered in settings where norepinephrine is unavailable or in patients with refractory septic shock and myocardial dysfunction. Owing to its potential effects on mortality and renal function and its norepinephrine-sparing effect, vasopressin is recommended as second-line vasopressor therapy instead of norepinephrine dose escalation in patients with septic shock and persistent arterial hypotension. However, two synthetic analogs of vasopressin, namely, terlipressin and selepressin, have not yet been employed in the management of patients with septic shock, as their use is associated with a higher rate of digital ischemia. Finally, angiotensin Ⅱ also appears to be a promising vasopressor in patients with septic shock, especially in the most severe cases and/or in patients with acute kidney injury requiring renal replacement therapy. Nevertheless, due to limited evidence and concerns regarding safety (which remains unclear because of potential adverse effects related to its marked vasopressor activity), angiotensin Ⅱ is currently not recommended in patients with septic shock. Further studies are needed to better define the role of these vasopressors in the management of these patients.

Methylene Blue Reduces Fluid Loading and Norepinephrine Requirements for Post-Resuscitation Syndrome in a Pig Model of Refractory Cardiac Arrest Resuscitated with Veno-Arterial ECMO

BACKGROUND

Refractory cardiac arrest management relies on extracorporeal cardiopulmonary resuscitation (ECPR), requiring the use of veno-arterial extracorporeal membrane oxygenation (VA-ECMO). Circulatory flow recovery can be associated with an ischemia-reperfusion injury, leading to vasoplegia and vasopressor requirement. The aim of this work was to evaluate the impact on hemodynamics of a methylene blue bolus infusion in a porcine model of ischemic refractory cardiac arrest.

METHODS

Ischemic refractory cardiac arrest was induced in 20 pigs. After a low flow period of 30 min, VA-ECMO was initiated and the pigs were randomly assigned to the standard care group (norepinephrine + crystalloids) or methylene blue group (IV 2 mg·kg-1 bolus of methylene blue over 30 min + norepinephrine and crystalloids). Macrocirculatory parameters and lactate clearance were measured. Sublingual microcirculation was evaluated with sidestream dark field (SDF) imaging. The severity of the ischemic digestive lesions was assessed according to the histologic Chiu/Park scale.

RESULTS

Eighteen pigs were included. The total crystalloid load (5000 (6000-8000) mL vs. 17,000 (10,000-19,000) mL, p = 0.007, methylene blue vs. standard care group) and catecholamine requirements (0.31 (0.14-0.44) μg·kg-1·min-1 vs. 2.32 (1.17-5.55) μg·kg-1·min-1, methylene blue vs. standard care group, p = 0.004) were significantly reduced in the methylene blue group. There were no significant between-group differences in lactate clearance, sublingual capillary microvascular parameters assessed by SDF or histologic Chiu/Park scale.

CONCLUSIONS

In our refractory cardiac arrest porcine model treated with ECPR, methylene blue markedly reduced fluid loading and norepinephrine requirements in comparison to standard care during the first 6 h of VA-ECMO.

Expanding the ZIFs Repertoire for Biological Applications with the Targeted Synthesis of ZIF-20 Nanoparticles

Owing to their facile synthesis, tailorable porosity, diverse compositions, and low toxicity, zeolitic imidazolate framework (ZIF) nanoparticles (NPs) have emerged as attractive platforms for a variety of biologically relevant applications. To date, a small subset of ZIFs representing only two topologies and very few linker chemistries have been studied in this realm. We seek to expand the bio-design space for ZIF NPs through the targeted synthesis of a hierarchically complex ZIF based on two types of cages, ZIF-20, with lta topology. This study demonstrates the rapid synthesis and size tunability of ZIF-20 particles across the micro and nanoregimes via microwave heating and the use of a modulating agent. To evaluate the utility of ZIF particles for biological applications, we examine their stability in biologically relevant media and demonstrate biocompatibility with A549 human epithelial cells. Further, the ability to encapsulate and release methylene blue, a therapeutic and bioimaging agent, is validated. Importantly, ZIF-20 NPs display a unique behavior relative to previously studied ZIFs based on their specific structural and chemical features. This finding highlights the need to expand the design space across the broader ZIFs family, to exploit a wider range of relevant properties for biological applications and beyond.

Effect of midodrine versus placebo on time to vasopressor discontinuation in patients with persistent hypotension in the intensive care unit (MIDAS): an international randomised clinical trial

PURPOSE

ICU discharge is often delayed by a requirement for intravenous vasopressor medications to maintain normotension. We hypothesised that the administration of midodrine, an oral α₁-adrenergic agonist, as adjunct to standard treatment shortens the duration of intravenous vasopressor requirement.

METHODS

In this multicentre, randomised, controlled trial including three tertiary referral hospitals in the US and Australia, we enrolled adult patients with hypotension requiring a single-agent intravenous vasopressor for ≥ 24 h. Subjects received oral midodrine (20 mg) or placebo every 8 h in addition to standard care until cessation of intravenous vasopressors, ICU discharge, or occurrence of adverse events. The primary outcome was time to vasopressor discontinuation. Secondary outcomes included time to ICU discharge readiness, ICU and hospital lengths of stay, and ICU readmission rates.

RESULTS

Between October 2012 and June 2019, 136 participants were randomised, of whom 132 received the allocated intervention and were included in the analysis (modified intention-to-treat approach). Time to vasopressor discontinuation was not different between midodrine and placebo groups (median [IQR], 23.5 [10-54] vs 22.5 [10.4-40] h; difference, 1 h; 95% CI - 10.4 to 12.3 h; p = 0.62). No differences in secondary endpoints were observed. Bradycardia occurred more often after midodrine administration (5 [7.6%] vs 0 [0%], p = 0.02).

CONCLUSION

Midodrine did not accelerate liberation from intravenous vasopressors and was not effective for the treatment of hypotension in critically ill patients.

Vasopressor-Sparing Action of Methylene Blue in Severe Sepsis and Shock: A Narrative Review

Shock is a serious acute circulatory failure leading to inadequate oxygen delivery to the cells. Its treatment is mainly based on circulating fluid optimization, and vasopressors to provide an adequate mean arterial pressure and microcirculatory flow. Norepinephrine is the drug of choice, but high dosages may be responsible for several side effects, including increased myocardial oxygen consumption, dysrhythmias, and peripheral and organ ischemia. Moreover, some patients are “non-responders” to first-line norepinephrine treatment. Hence, other drugs have been proposed to reach and maintain the hemodynamic target. In general, they are described as catecholamine-sparing agents. Among others, the most used are vasopressin, corticosteroids, and angiotensin II. Methylene blue (MB) represents a further option, even though its use is still a topic of controversy. This review article tries to summarize what is known and unknown about the actions of MB in patients in shock. It reduces excessive production of nitric oxide via blockade of guanylate cyclase in shock states. At present, it appears the MB provides positive results in septic shock, if administered early. Further randomized controlled trials are warranted regarding its use to provide more precise indications to physicians involved in the treatment of such patients.

Comparative Study Regarding the Properties of Methylene Blue and Proflavine and Their Optimal Concentrations for In Vitro and In Vivo Applications

Methylene blue and proflavine are fluorescent dyes used to stain nucleic acid from the molecular level to the tissue level. Already clinically used for sentinel node mapping, detection of neuroendocrine tumors, methemoglobinemia, septic shock, ifosfamide-induced encephalopathy, and photodynamic inactivation of RNA viruses, the antimicrobial, anti-inflammatory, and antioxidant effect of methylene blue has been demonstrated in different in vitro and in vivo studies. Proflavine was used as a disinfectant and bacteriostatic agent against many gram-positive bacteria, as well as a urinary antiseptic involved in highlighting cell nuclei. At the tissue level, the anti-inflammatory effects of methylene blue protect against pulmonary, renal, cardiac, pancreatic, ischemic-reperfusion lesions, and fevers. First used for their antiseptic and antiviral activity, respectively, methylene blue and proflavine turned out to be excellent dyes for diagnostic and treatment purposes. In vitro and in vivo studies demonstrated that both dyes are efficient as perfusion and tissue tracers and permitted to evaluate the minimal efficient concentration in different species, as well as their pharmacokinetics and toxicity. This review aims to identify the optimal concentrations of methylene blue and proflavine that can be used for in vivo experiments to highlight the vascularization of the skin in the case of a perforasome (both as a tissue tracer and in vascular mapping), as well as their effects on tissues. This review is intended to be a comparative and critical presentation of the possible applications of methylene blue (MB) and proflavine (PRO) in the surgical field, and the relevant biomedical findings from specialized literature to date are discussed as well.

New titania-based photocatalysts for hydrogen production from aqueous-alcoholic solutions of methylene blue

A series of CuO_x–TiO₂ photocatalysts were prepared using fresh and thermally activated Evonik Aeroxide P25 titanium dioxide. The photocatalysts were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, XANES, diffuse reflectance spectroscopy, and N₂ adsorption technique. Photocatalytic activity of the samples was tested in hydrogen production from aqueous-alcoholic solutions of methylene blue under UV radiation (λ = 386 nm). It was found for the first time the synergistic effect of hydrogen production from two substrates—dye and ethanol. The maximum hydrogen production rate in the system water–ethanol–methylene blue was 1 μmol min⁻¹, which is 25 times higher than a value measured in a 10% solution of ethanol in water. The thermal activation of titania also leads to a change in the rate of hydrogen production. The highest catalytic activity was observed for a CuO_x–TiO₂ photocatalyst based on titania thermally-activated at 600 °C in air. A mechanism of the photocatalytic reaction is discussed.

Simultaneous presence of ethanol and methylene blue was shown to provide the most efficient hydrogen production and methylene blue removal.