Infusion of methylene blue in human septic shock: a pilot, randomized, controlled study

Prolonged methylene blue infusion in refractory septic shock: a case report

PURPOSE

Methylene blue (MB) has been advocated for the treatment of refractory hemodynamic instability in patients with septic shock. However, the use of MB infusions in septic shock is not considered standard treatment, and the available literature describes infusions of short duration, typically less than six hours.

CLINICAL FEATURES

We report a case of septic shock in a 67-yr-old male who required maximal vasopressor support with norepinephrine, epinephrine, and vasopressin. Despite standard protocols for the treatment of septic shock, the patient's hemodynamic status was refractory 80 hr post admission. However, initiation of a MB infusion resulted in the rapid restoration of hemodynamic stability and a subsequent decrease in vasopressor requirements. Multiple attempts to discontinue the MB infusion resulted in immediate and repeated increases in vasopressor requirements, necessitating a continuous infusion with a slow taper of MB for 120 hr. Ultimately, the patient survived the illness and was discharged home. We observed no adverse events that could be attributed to the use of MB.

CONCLUSION

In our patient, the use of MB resulted in hemodynamic stability unattained with standard vasopressor support. Further research is warranted on the use of MB in patients with septic shock.

Vasopressin and methylene blue: alternate therapies in vasodilatory shock

Cardiac surgery with cardiopulmonary bypass (CPB) is frequently complicated by vasoplegic syndrome, a vasodilatory shock state. Traditional treatment based on fluid resuscitation and catecholamine drugs is ineffective in a number of patients. Clinical trials investigating both vasopressin and methylene blue as additional rescue or preventative therapy are reviewed. Vasopressin is suggested to retain its vasoconstrictive power in hypoxemia and acidosis, lower pulmonary hypertension, reduce supraventricular arrhythmias, and accelerate intensive care unit (ICU) recovery. Safety concerns include frequent thrombocytopenia and potentially altered mesenteric and renal perfusion. Methylene blue is suggested to facilitate CPB weaning, reduce renal, respiratory, arrhythmic, and septic complications, reduce mortality, and accelerate ICU and hospital recovery. Safety concerns include oximeter interference, pulmonary hypertension, neurotoxicity, arrhythmias, and potentially altered coronary, mesenteric, and renal perfusion. Research on both molecules is ongoing and has yet to confirm on a larger scale their efficacy and safety as treatments for post-CPB vasoplegic syndrome.

Vascular hyporesponsiveness to vasopressors in septic shock: from bench to bedside

PURPOSE

To delineate some of the characteristics of septic vascular hypotension, to assess the most commonly cited and reported underlying mechanisms of vascular hyporesponsiveness to vasoconstrictors in sepsis, and to briefly outline current therapeutic strategies and possible future approaches.

METHODS

Source data were obtained from a PubMed search of the medical literature with the following MeSH terms: Muscle, smooth, vascular/physiopathology; hypotension/etiology; shock/physiopathology; vasodilation/physiology; shock/therapy; vasoconstrictor agents.

RESULTS

Nitric oxide (NO) and peroxynitrite are crucial components implicated in vasoplegia and vascular hyporeactivity. Vascular ATP-sensitive and calcium-activated potassium channels are activated during shock and participate in hypotension. In addition, shock state is characterized by inappropriately low plasma glucocorticoid and vasopressin concentrations, a dysfunction and desensitization of alpha-receptors, and an inactivation of catecholamines by oxidation. Numerous other mechanisms have been individualized in animal models, the great majority of which involve NO: MEK1/2-ERK1/2 pathway, H(2)S, hyperglycemia, and cytoskeleton dysregulation associated with decreased actin expression.

CONCLUSIONS

Many therapeutic approaches have proven their efficiency in animal models, especially therapies directed against one particular compound, but have otherwise failed when used in human shock. Nevertheless, high doses of catecholamines, vasopressin and terlipressin, hydrocortisone, activated protein C, and non-specific shock treatment have demonstrated a partial efficiency in reversing sepsis-induced hypotension.

Methylene blue for the treatment of septic shock

Septic shock is a major cause of morbidity and mortality in the intensive care unit, and effective therapies are limited. Methylene blue is a selective inhibitor of guanylate cyclase, a second messenger involved in nitric oxide-mediated vasodilation. The use of methylene blue in the treatment of septic shock has been repeatedly evaluated over the past 20 years, but data remain scarce. To evaluate the safety and efficacy of methylene blue for the treatment of septic shock, we conducted a literature search of the EMBASE (1974-June 2009), MEDLINE (1966-June 2009), and International Pharmaceutical Abstracts (1970-June 2009) databases. All available studies published in English were reviewed. Observational studies with methylene blue have demonstrated beneficial effects on hemodynamic parameters and oxygen delivery, but use of methylene blue may be limited by adverse pulmonary effects. Methylene blue administration is associated with increases in mean arterial pressure while reducing catecholamine requirements in patients experiencing septic shock; however, its effects on morbidity and mortality remain unknown. Well-designed, prospective evaluations are needed to define the role of methylene blue as treatment of septic shock.

A dose-finding study of methylene blue to inhibit nitric oxide actions in the hemodynamics of human septic shock

Methylene blue increases blood pressure and myocardial function in septic shock mainly by inhibiting nitric oxide (NO) actions. However, a dose-dependency of methylene blue has not been established. Therefore, the compound is currently used as rescue treatment only. To evaluate dose-dependency, a prospective, randomized, double blind, single centre study was performed in 15 consecutive, mechanically ventilated patients with septic shock admitted to the intensive care unit, in whom methylene blue was infused at 1 mg/kg (n=4), 3 mg/kg (n=6) or 7 mg/kg (n=5) over 20 min. Hemodynamic parameters were measured before and after the infusion. Gastric tonometry was performed. Methylene blue treatment increased heart rate, cardiac index, mean arterial, pulmonary artery, pulmonary artery occlusion and central venous pressures, systemic vascular resistance, ventricular stroke work indices and O(2) delivery and uptake, and decreased lactate levels. Methylene blue had a dose-dependent effect on cardiac index, mean arterial, mean pulmonary artery and pulmonary artery occlusion pressures, left ventricular function, O(2) delivery and consumption and lactate levels. The drug dose-dependently increased the gastric-arterial blood PCO(2) gap. The data suggest that in human septic shock, methylene blue increases mean arterial blood pressure by an increase in cardiac index and systemic vascular resistance. The rise in cardiac index is caused by an increase in left ventricular filling and function, increasing tissue oxygenation, even at a dose of 1mg/kg. High doses of methylene blue may compromise splanchnic perfusion, even though further enhancing global hemodynamics, and should therefore, be avoided in future studies.

Selective iNOS inhibition for the treatment of sepsis-induced acute kidney injury

The incidence and mortality of sepsis and the associated development of acute kidney injury (AKI) remain high, despite intense research into potential treatments. Targeting the inflammatory response and/or sepsis-induced alterations in the (micro)circulation are two therapeutic strategies. Another approach could involve modulating the downstream mechanisms that are responsible for organ system dysfunction. Activation of inducible nitric oxide (NO) synthase (iNOS) during sepsis leads to elevated NO levels that influence renal hemodynamics and cause peroxynitrite-related tubular injury through the local generation of reactive nitrogen species. In many organs iNOS is not constitutively expressed; however, it is constitutively expressed in the kidney and, in humans, a relationship between the upregulation of renal iNOS and proximal tubular injury during systemic inflammation has been demonstrated. For these reasons, the selective inhibition of renal iNOS might have important implications for the treatment of sepsis-induced AKI. Various animal studies have demonstrated that selective iNOS inhibition-in contrast to nonselective NOS inhibition-attenuates sepsis-induced renal dysfunction and improves survival, a finding that warrants investigation in clinical trials. In this Review, the selective inhibition of iNOS as a potential novel treatment for sepsis-induced AKI is discussed.

sGC(alpha)1(beta)1 attenuates cardiac dysfunction and mortality in murine inflammatory shock models

Altered cGMP signaling has been implicated in myocardial depression, morbidity, and mortality associated with sepsis. Previous studies, using inhibitors of soluble guanylate cyclase (sGC), suggested that cGMP generated by sGC contributed to the cardiac dysfunction and mortality associated with sepsis. We used sGC(alpha)(1)-deficient (sGC(alpha)(1)(-/-)) mice to unequivocally determine the role of sGC(alpha)(1)beta(1) in the development of cardiac dysfunction and death associated with two models of inflammatory shock: endotoxin- and TNF-induced shock. At baseline, echocardiographic assessment and invasive hemodynamic measurements of left ventricular (LV) dimensions and function did not differ between wild-type (WT) mice and sGC(alpha)(1)(-/-) mice on the C57BL/6 background (sGC(alpha)(1)(-/-B6) mice). At 14 h after endotoxin challenge, cardiac dysfunction was more pronounced in sGC(alpha)(1)(-/-B6) than WT mice, as assessed using echocardiographic and hemodynamic indexes of LV function. Similarly, Ca(2+) handling and cell shortening were impaired to a greater extent in cardiomyocytes isolated from sGC(alpha)(1)(-/-B6) than WT mice after endotoxin challenge. Importantly, morbidity and mortality associated with inflammatory shock induced by endotoxin or TNF were increased in sGC(alpha)(1)(-/-B6) compared with WT mice. Together, these findings suggest that cGMP generated by sGC(alpha)(1)beta(1) protects against cardiac dysfunction and mortality in murine inflammatory shock models.

Nitric oxide and vascular reactivity in sepsis

Sepsis and septic shock are major causes of morbidity and mortality in critically ill patients. Sepsis and septic shock induce a profound fall in the peripheral vascular tone. NO has been implicated as a key player in vascular changes of sepsis and septic shock. In this brief review, two points are focused in greater detail: first, the involvement of guanylate cyclase and potassium channels in NO vascular effects in sepsis; second, the role played by NO and its two effectors in the long-lasting modifications of vascular reactivity in sepsis. Some recent developments in the area are reviewed.

Methylene blue in the treatment of vasoplegia following severe burns

Vasoplegia resulting from severe burns may persist despite adequate fluid resuscitation and treatment with norepinephrine (NE), vasopressin (VP), and steroids. The adenylate cyclase inhibitor methylene blue (MB), currently used in the burn patient to treat methemoglobinemia, has been used to treat vasoplegia after cardiopulmonary bypass. We report the case of MB infusion in two burn patients refractory to NE. The patients had severe burns, 95 and 80% TBSA not responding to conventional treatment. Fluid requirements were estimated according to Parkland formula and then to maintain a urinary output of 30-50 ml/hr. Patient #1, 95% TBSA, was adrenally insufficient and was receiving steroids according to the Annane protocol, as well as VP at 0.2 U/min. His NE requirements were 55 mcg/kg/min. Patient #2, 80% TBSA, was receiving 20 mcg/kg/min of NE. Circulatory failure was defined as inability to maintain mean arterial pressure >70 mm Hg. Hemodynamic and physiologic parameters were measured before and after infusion of a single dose of 2 mg/kg of MB. Both patients showed dramatic improvements in their shock after MB. Patient #1 had an initial reaction within 30 minutes and reached peak effect at 1 hour. His NE requirements decreased to 0.2 mcg/kg/min and VP decreased to 0.04 U/min. Patient #2 showed effects within 15 minutes of the infusion and by 2 hours the NE was stopped. No adverse side effects were noted in either of the two patients. The fact that MB successfully reversed refractory vasoplegia after severe burns suggests a new tool for treating a small subgroup of patients who exhibit persistent vasoplegia from their burn injury. A controlled randomized trial is needed to test its effects on a large number of patients and graft survival.

Neuro- and cardioprotective effects of blockade of nitric oxide action by administration of methylene blue

Methylene blue (MB), generic name methylthioninium (C(16)H(18)ClN(3) S . 3H(2)O), is a blue dye synthesized in 1876 by Heinrich Caro for use as a textile dye and used in the laboratory and clinically since the 1890s, with well-known toxicity and pharmacokinetics. It has experimentally proven neuroprotective and cardioprotective effects in a porcine model of global ischemia-reperfusion in experimental cardiac arrest. This effect has been attributed to MB's blocking effect on nitric oxide synthase and guanylyl cyclase, the latter blocking the synthesis of the second messenger of nitric oxide. The physiological effects during reperfusion include stabilization of the systemic circulation without significantly increased total peripheral resistance, moderately increased cerebral cortical blood flow, a decrease of lipid peroxidation and inflammation, and less anoxic tissue injury in the brain and the heart. The last two effects are recorded as less increase in plasma concentrations of astroglial protein S-100beta, as well as troponin I and creatine kinase isoenzyme MB, respectively.

Is There NO Treatment For Severe Sepsis?

Sepsis is a systemic inflammatory response syndrome in the presence of suspected or proven infection, and it may progress to or encompass organ failure (severe sepsis) and hypotension (septic shock). Clinicians possess an arsenal of supportive measures to combat severe sepsis and septic shock, and some success, albeit controversial, has been achieved by using low doses of corticosteroids or recombinant human activated protein C. However, a truly effective mediator-directed specific treatment has not been developed yet. Treatment with low doses of corticosteroids or with recombinant human activated protein C remains controversial and its success very limited. Attempts to treat shock by blocking LPS, TNF or IL-1 were unsuccessful, as were attempts to use interferon-gamma or granulocyte colony stimulating factor. Inhibiting nitric oxide synthases held promise but met with considerable difficulties. Scavenging excess nitric oxide or targeting molecules downstream of inducible nitric oxide synthase, such as soluble guanylate cyclase or potassium channels, might offer other alternatives.

Short-term beneficial effects of methylene blue on kidney damage in septic shock patients

Objective

We previously demonstrated that upregulation of renal inducible nitric oxide synthase (iNOS) is associated with proximal tubule injury during systemic inflammation in humans. In this study we investigated the short-term effect of methylene blue (MB), an inhibitor of the NO pathway, on kidney damage and function in septic shock patients.

Design and setting

A prospective clinical study conducted in an intensive care unit.

Patients

Nine patients (four men, five women, mean age 71 ± 3 years) with confirmed or suspected bacterial infection and with refractory septic shock defined as a mean arterial pressure ≤ 70 mmHg despite norepinephrine infusion ≥ 0.2 μg/kg per minute.

Interventions

A 4 h continuous intravenous infusion of 1 mg/kg MB per hour.

Measurements and results

The urinary excretion of NO metabolites decreased with median 90% (range 75–95%) from baseline to 6 h after MB administration. The first 24 h creatinine clearance improved by 51% (18–173%) after MB treatment but was still strongly impaired. During the first 6 h after the start of MB treatment both the urinary excretion of cytosolic glutathione S-transferase A1-1 and P1-1, markers for proximal and distal tubule damage, respectively, decreased by 45% (10–70%) and 70% (40–85) vs. baseline. After termination of the MB infusion the NO metabolites and markers of tubular injury returned to pretreatment levels.

Conclusions

In septic patients with refractory shock short-term infusion of MB is associated with a decrease in NO production and an attenuation of the urinary excretion of renal tubular injury markers.

Electronic supplementary material

The online version of this article (doi:10.1007/s00134-007-0867-9) contains supplementary material, which is available to authorized users.

Cardio-cerebral and metabolic effects of methylene blue in hypertonic sodium lactate during experimental cardiopulmonary resuscitation

BACKGROUND

Methylene blue (MB) administered with a hypertonic-hyperoncotic solution reduces the myocardial and cerebral damage due to ischaemia and reperfusion injury after experimental cardiac arrest and also increases short-term survival. As MB precipitates in hypertonic sodium chloride, an alternative mixture of methylene blue in hypertonic sodium lactate (MBL) was developed and investigated during and after cardiopulmonary resuscitation (CPR).

METHODS

Using an experimental pig model of cardiac arrest (12 min cardiac arrest and 8 min CPR) the cardio-cerebral and metabolic effects of MBL (n=10), MB in normal saline (MBS; n=10) or in hypertonic saline dextran (MBHSD; n=10) were compared. Haemodynamic variables and cerebral cortical blood flow (CCBF) were recorded. Biochemical markers of cerebral oxidative injury (8-iso-PGF2alpha), inflammation (15-keto-dihydro-PGF2alpha), and neuronal damage (protein S-100beta) were measured in blood from the sagittal sinus, whereas markers of myocardial injury, electrolytes, and lactate were measured in arterial plasma.

RESULTS

There were no differences between groups in survival, or in biochemical markers of cerebral injury. In contrast, the MBS group exhibited not only increased CKMB (P<0.001) and troponin I in comparison with MBHSD (P=0.019) and MBL (P=0.037), but also greater pulmonary capillary wedge pressure 120 min after return of spontaneous circulation (ROSC). Lactate administration had an alkalinizing effect started 120 min after ROSC.

CONCLUSIONS

Methylene blue in hypertonic sodium lactate may be used against reperfusion injury during experimental cardiac arrest, having similar effects as MB with hypertonic saline-dextran, but in addition better myocardial protection than MB with normal saline. The neuroprotective effects did not differ.

Sepsis and the heart

Sepsis is generally viewed as a disease aggravated by an inappropriate immune response encountered in the afflicted individual. As an important organ system frequently compromised by sepsis and always affected by septic shock, the cardiovascular system and its dysfunction during sepsis have been studied in clinical and basic research for more than 5 decades. Although a number of mediators and pathways have been shown to be associated with myocardial depression in sepsis, the precise cause remains unclear to date. There is currently no evidence supporting global ischemia as an underlying cause of myocardial dysfunction in sepsis; however, in septic patients with coexistent and possibly undiagnosed coronary artery disease, regional myocardial ischemia or infarction secondary to coronary artery disease may certainly occur. A circulating myocardial depressant factor in septic shock has long been proposed, and potential candidates for a myocardial depressant factor include cytokines, prostanoids, and nitric oxide, among others. Endothelial activation and induction of the coagulatory system also contribute to the pathophysiology in sepsis. Prompt and adequate antibiotic therapy accompanied by surgical removal of the infectious focus, if indicated and feasible, is the mainstay and also the only strictly causal line of therapy. In the presence of severe sepsis and septic shock, supportive treatment in addition to causal therapy is mandatory. The purpose of this review is to delineate some characteristics of septic myocardial dysfunction, to assess the most commonly cited and reported underlying mechanisms of cardiac dysfunction in sepsis, and to briefly outline current therapeutic strategies and possible future approaches.

Nitric oxide in shock

Refractory hypotension with end-organ hypoperfusion and failure is an ominous feature of shock. Distributive shock is caused by severe infections (septic shock) or severe systemic allergic reactions (anaphylactic shock). In 1986, it was concluded that nitric oxide (NO) is the endothelium-derived relaxing factor that had been discovered 6 years earlier. Since then, NO has been shown to be important for the physiological and pathological control of vascular tone. Nevertheless, although inhibition of NO synthesis restores blood pressure, NO synthase (NOS) inhibition cannot improve outcome, on the contrary. This implies that NO acts as a double-edged sword during septic shock. Consequently, the focus has shifted towards selective inducible NOS (iNOS) inhibitors. The contribution of NO to anaphylactic shock seems to be more straightforward, as NOS inhibition abrogates shock in conscious mice. Surprisingly, however, this shock-inducing NO is not produced by the inducible iNOS, but by the so-called constitutive enzyme endothelial NOS. This review summarizes the contribution of NO to septic and anaphylactic shock. Although NOS inhibition may be promising for the treatment of anaphylactic shock, the failure of a phase III trial indicates that other approaches are required for the successful treatment of septic shock. Amongst these, high hopes are set for selective iNOS inhibitors. But it might also be necessary to shift gears and focus on downstream cardiovascular targets of NO or on other vasodilating phenomena.

Is the cyclic GMP system underestimated by intensive care and emergency teams?

At present, the clinical management inflammatory vasoplegia associated to sepsis or anaphylaxis is symptomatic. Volume is expanded by means of administration of fluids, and low blood pressure is managed by means of administration of positive inotropes and vasoconstrictors. This therapeutic approach is mainly associated to the cyclic AMP (cAMP) and, many times the circulatory shock is refractory to high amines concentrations. However, beside of cAMP-dependent vasoreactivity mechanisms there are other two known vasoplegia involved mechanisms: cyclic GMP (cGMP) and hyperpolarization that is less clinically considered. Also, it is possible to speculate about 'probable vasopressin deficiency'. Methylene blue (MB) is the most useful and clinically safe cGMP blocker. We propose a decision tree for diagnosis and institution of this therapeutical approach many times underestimate by intensive care and emergency teams.

Complement-related molecular events in sepsis leading to heart failure

Despite intensive ongoing research efforts, the mortality of patients with sepsis remains unacceptably high. A significant number of clinical trials have failed to produce sufficient therapeutic strategies despite showing promising results in animal models. So far, many studies have focused on deterioration of the humoral and cellular components of the immune system, the main cause of death in septic patients being multi-organ failure. However, not much is known about the effects of the complement system on parenchymal cells of organs such as the heart. Recently, septic cardiomyopathy has been recognized as one of the major complications during sepsis, often determining the clinical outcome. In this review, we describe molecular events which are thought to be related to cardiac dysfunction during sepsis. A special emphasis will be placed on the complement system, which generates powerful anaphylatoxins (such as C5a) and which has recently been associated with septic cardiomyopathy. Together with the impact on cardiac function of various cytokines we will provide a synopsis of the current knowledge regarding the pathophysiology underlying cardiac failure during sepsis with a special emphasis on C5a and C5aR.

Use of methylene blue in sepsis: a systematic review

A systematic review of the literature was conducted to determine if the administration of methylene blue in humans improves hemodynamic status and/or outcome in patients with septic shock. Studies were identified from MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials database. The review included human studies of patients with septic shock treated with methylene blue in which hemodynamic variables or mortality rates were reported. An electronic form was used to extract items including study design, population characteristics, intervention details, and outcomes. No meta-analysis was performed. Methylene blue administration in patients with septic shock increases mean arterial pressure and systemic vascular resistance while decreasing vasopressor requirements. Increased pulmonary vascular resistance has been reported with bolus administration but might be avoided by continuous infusion. No other ill effects were reported. Effects on mortality have not been adequately evaluated in the literature.

Methylene blue decreases ischemia-reperfusion (I/R)-induced spinal cord injury: an in vivo study in an I/R rabbit model

OBJECTIVES

To evaluate the effects of intravenous methylene blue (MB) administration on ischemia-reperfusion (I/R) injury of the spinal cord (SC).

METHODS

16 rabbits were randomly assigned either to group M (n = 8; receiving MB, intervention group) or group C (n = 8; control group) and underwent a 30-min period of SC ischemia by clamping the abdominal aorta between the left renal artery and the aortic bifurcation. 15 min before clamping, rabbits received either intravenous MB (10 mg/kg; group M) or normal saline (group C). The two groups were compared 24 h postoperatively both histologically and for neurological function, using a Tarlov score. Measurements to determine levels of malondialdehyde (MDA) and glutathione (GSH) in the SC tissue were also performed.

RESULTS

Neurological impairment and spinal tissue MDA levels were significantly lower in animals treated with MB (p < 0.001). In contrast, spinal GSH levels were significantly higher in group M (p < 0.001). Histological examination revealed that the integrity of the SC was better preserved in the MB group, whereas cords from the control group exhibited evidence of acute neuronal injury.

CONCLUSIONS

The prophylactic use of MB reduces neurological injury and improves clinical outcomes in the rabbit SC I/R model. These effects are probably mediated by the drug's antioxidant properties.

Utilización de azul de metileno en el tratamiento del síndrome vasopléjico del postoperatorio de cirugía cardíaca

Vasoplegia is a frequent complication in post-operative heart surgery and determines a significant increase in morbidity-mortality. When vasoplegia persists in spite of optimized fluid therapy with the use of Swan-Ganz catheter, we have a safe, effective and economical alternative, methylene blue. We present the case of a patient who developed vasoplegia refractory to treatment and shock in the scheduled post-operative period of myocardial revascularization. The use of a single dose of methylene blue resolved the hemodynamic instability and allowed for total discontinuation of vasoactive drugs. Thus, we present this new indication of methylene blue, still not approved by the corresponding bodies, for which no national publications have been found and its clinical management and the absence of adverse effects after its use.

The hemodynamic effects of methylene blue when administered at the onset of cardiopulmonary bypass

Hypotension occurs during cardiopulmonary bypass (CPB), in part because of induction of the inflammatory response, for which nitric oxide and guanylate cyclase play a central role. In this study we examined the hemodynamic effects of methylene blue (MB), an inhibitor of guanylate cyclase, administered during cardiopulmonary bypass (CPB) to patients taking angiotensin-converting enzyme inhibitors. Thirty patients undergoing cardiac surgery were randomized to receive either MB (3 mg/kg) or saline (S) after institution of CPB and cardioplegic arrest. CPB was managed similarly for all study patients. Hemodynamic data were assessed before, during, and after CPB. The use of vasopressors was recorded. All study patients experienced a similar reduction in mean arterial blood pressure (MAP) and systemic vascular resistance (SVR) with the onset of CPB and cardioplegic arrest. MB increased MAP and SVR and this effect lasted for 40 minutes. The saline group demonstrated a persistently reduced MAP and SVR throughout CPB. The saline group received phenylephrine more frequently during CPB, and more norepinephrine after CPB to maintain a desirable MAP. The MB group recorded significantly lower serum lactate levels despite equal or greater MAP and SVR. In conclusion, administration of MB after institution of CPB for patients taking angiotensin-converting enzyme inhibitors increased MAP and SVR and reduced the need for vasopressors. Furthermore, serum lactate levels were lower in MB patients, suggesting more favorable tissue perfusion.

Methylene blue for diagnosis of displaced atrial lines

Methylene blue (aniline violet, tetra-methylthionine chloride) has several important uses in clinical medicine, including diagnosis of displaced central lines. After cardiac surgery, three infants with suspected displacement of direct atrial lines were given methylene blue. After injection of the dye into the atrial lines, bluish discolouration was identified in their chest drainage. Use of methylene blue in small amounts appears to be a safe and effective way of diagnosing extravasation of fluid from displaced central lines.

The Effects of Methylene Blue on Lung Injury in Septic Rats

PURPOSE

We aimed to investigate the effects of methylene blue (MB) on NO production, myeloperoxidase (MPO) activity, antioxidant status and lipid peroxidation in lung injury during different stages of sepsis in rats.

MATERIAL AND METHODS

Rats were randomly divided into 4 groups (n = 20): group C, sham operated; group CMB, sham operated and receiving MB (25 mg/kg, i.p.); group S, sepsis; group SMB, sepsis and receiving MB (25 mg/kg, i.p.). Sepsis was induced by cecal ligation and puncture (CLP). The MB dose was administered after CLP. Each group was subdivided into two subgroups (n = 10) which were sacrificed at 9 or 18 h after the surgical procedure. The levels of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-PX) and MPO activity, total nitrite/nitrate and malondialdehyde (MDA) in the lung tissue were measured. Lung injury was graded from 1 (injury to 25% of the field) to 4 (diffuse injury) by the pathologist.

RESULTS

In group SMB, while SOD and CAT increased in both early and late sepsis periods, GSH-PX increased significantly only in the early sepsis period when compared with group S. Increase in lung MPO activity after CLP-induced sepsis was prevented by MB administration. MB significantly decreased to nitrite/nitrate and MDA levels both in early and late sepsis periods when compared with group S (p < 0.05). Group S showed a marked increase in neutrophil infiltration into the interstitial space and thickening of the alveolar septa, whereas the alveolar damage score was lower in the SMB group (p < 0.05).

CONCLUSION

MB reduced the MPO activity and lipid peroxidation by both decreasing oxidative stress and NO overproduction in the lungs, which resulted in the attenuation of lung injury after CLP-induced sepsis in rats.

Uroscopic rainbow: modern matula medicine

Visual inspection of a patient's urine has long been used by physicians, with colour recognised as having important clinical implications. In this review the authors will revisit this ancient pastime with relevance to contemporary medical practice.

Nitric oxide-dependent reduction in soluble guanylate cyclase functionality accounts for early lipopolysaccharide-induced changes in vascular reactivity

We investigated the role of soluble guanylate cyclase in lipopolysaccharide-induced hyporesponsiveness to phenylephrine. The effects of phenylephrine on the blood pressure of female Wistar rats were evaluated at 2, 8, and 24 h after lipopolysaccharide injection (12.5 mg/kg i.p.). Vasoconstrictive responses to phenylephrine were reduced 40 to 50% in all time periods. Methylene blue, a soluble guanylate cyclase inhibitor (15 micromol/kg i.v.) restored the reactivity to phenylephrine in animals injected with lipopolysaccharide 2 and 24 h earlier. However, it failed to do so in animals injected with lipopolysaccharide 8 h earlier. Incubation with sodium nitroprusside (SNP) increased lung and aorta cGMP levels in control animals and in tissues of rats treated with lipopolysaccharide 24 h earlier. However, SNP failed to increase tissue cGMP in rats injected 8 h earlier. Lipopolysaccharide reduced the vasodilatory response to NO donors 8 h after injection. This effect and the decreased lung cGMP accumulation in response to SNP were reversed by an NO synthase blocker. Guanylate cyclase protein levels were lower than controls in lungs harvested from rats injected 8 h earlier and were back to normal values in lungs of rats injected 24 h earlier with lipopolysaccharide. Thus, data indicate that there is a temporal window of 8 h after lipopolysaccharide injection in which soluble guanylate cyclase is not functional and that this loss of function is NO-dependent. Thus, the putative use of soluble guanylate cyclase inhibitors in the treatment of endotoxemia may be beneficial mainly at early stages of this condition.

Sepsis and myocardial depression in a young woman

Severe sepsis may be associated with depression of myocardial function, attributed to various inflammatory mediators. Myocardial dysfunction in sepsis is characterized by biventricular failure and complicates usual therapy with high-volume fluid resuscitation and vasopressors. However, in patients who survive septic shock, myocardial dysfunction can improve rapidly. We describe a young woman with septic shock due to Streptococcus pneumoniae, complicated by severe but reversible biventricular dysfunction.

The effects of methylene blue on hemodynamic parameters and cytokine levels in refractory septic shock

BACKGROUND

Endogenous nitric oxide (NO) induces the peripheral vasodilation via the activation of guanylate cyclase in patients with septic shock. The purpose of this study was to assess the acute effects of methylene blue (MB), which is an inhibitor of guanylate cyclase, on the hemodynamics and on the production of pro-inflammatory cytokines and nitric oxide (NO) in patients with refractory septic shock.

METHODS

Twenty consecutive patients with refractory septic shock, which was defined as shock refractory to a dopamine infusion of more than 20 microg/kg/min with the appropriate use of antibiotics and adequate volume replacement, received MB infusion of 1 mg/kg intravenously. The hemodynamic and respiratory variables were measured at baseline, 30, 60 and 120 min after an infusion of MB (1 mg/kg). The blood levels of NO, IL-1, IL-10 and TNF-alpha were measured at baseline, 30 and 120 min after MB infusion.

RESULTS

The administration of MB induced an increase in the systemic vascular resistance (SVR) that resulted in an increase of the mean arterial pressure (MAP) in patients with refractory septic shock, and this was without a decrease in cardiac output. The administered MB induced an increase in pulmonary vascular resistance (PVR) that resulted in an increase of pulmonary arterial pressure (PAP), without any deterioration of gas exchange. However, the increases in SVR and PVR were not associated with the alteration of endogenous production of NO, IL-1, IL-10 and TNF- alpha.

CONCLUSION

MB transiently elevated the MAP by increasing the SVR without altering the endogenous productions of NO, IL-1, IL-10 and TNF- alpha during the study period in patients with refractory septic shock.

Methylthioninium chloride: pharmacology and clinical applications with special emphasis on nitric oxide mediated vasodilatory shock during cardiopulmonary bypass

Vasodilatory shock after cardiopulmonary bypass is a common complication requiring treatment with high doses of inotropes and prolonged stays in the intensive care unit. The vasodilatory shock is initiated by an inflammatory response to the extracorporeal circuit. The inflammatory response results in endothelial synthesis and release of nitric oxide resembling the clinical features observed in vasodilatory shock caused by septicaemia. During vasodilatory shock, the inhibition of nitric oxide synthase and the nitric oxide/cyclic guanylyl monophosphate pathway is an attractive adjunct to therapy with traditional inotropes. Methylthioninium chloride inhibits nitric oxide/cyclic guanylyl monophosphate mediated vasodilation and can successfully be used as a supplement in the treatment of vasodilatory shock associated with cardiopulmonary bypass. The application of methylthioninium chloride in septicaemia has not produced comparable positive clinical results.

Inotropes and vasopressors in adults and foals

Successful treatment with inotropes and vasopressors depends on an understanding of the interplay of flow, pressure, and resistance in the cardiovascular system and an appreciation of the pathophysiologic mechanisms leading to inadequate tissue perfusion. Any treatment strategy is necessarily a compromise between the requirements of different vascular beds.Furthermore. the underlying hemodynamic derangements can change rapidly. Therefore. inotropes and vasopressors should be titrated to measures of improved hemodynamic status, and the treatments should be frequently reviewed.

Matching total body oxygen consumption and delivery: a crucial objective?

The strength of the rationale for incorporating total body oxygen consumption (VO(2)) and delivery (DO(2)) into our decision making strategies contrasts with the absence of demonstrated benefits of bedside calculations in clinical practice. This situation mandates a careful reappraisal of the theoretical limitations of bedside calculations of DO(2) and VO(2), including a re-evaluation of the clinical situations in which these calculations are valid. Three levels of complexity can be distinguished when analysing a patient's hemodynamic status: 1) simple cases where investigations can be limited to clinical monitoring, including lactate changes over time; 2) intermediate situations requiring invasive investigations in which continuous monitoring of VO(2)-related variables such as cardiac output and mixed venous oxygen saturation often provide enough information to guide clinical decision; and 3) complex situations where assessment of VO(2) and VO(2)/DO(2) analysis might be recommended. Although studies that support such recommendations are limited they are based on a widely accepted physiological model. VO(2) and DO(2) analysis is also limited by theoretical and technical difficulties. In this article, we discuss the validity of these limitations in the bedside assessment of VO(2) and DO(2), and review data supporting the use of VO(2)/DO(2) analysis in the clinical evaluation of complex cases.

Methylene blue attenuates lung injury after mesenteric artery clamping/unclamping

BACKGROUND

This controlled, experimental study was designed to assess the effects of intratracheal and intravenous methylene blue on reperfusion lung injury following superior mesenteric artery clamping/unclamping.

MATERIALS AND METHODS

Superior mesenteric arteries of 144 anaesthetized adult male Wistar rats (n = 12/group) were clamped for 1 h. Ten minutes before unclamping, methylene blue or its vehicle was administered intratracheally or intravenously, followed by a 3 h-respiratory assessment and postexperimental assessment of survival.

RESULTS

Intravenous 3 and 9 mg kg(-1) but not higher methylene blue doses, and intratracheal 6-mg kg(-1) but not lower doses, significantly (P < 0.05) reduced the 100% increase in plateau pressure, 30% reduction in PO(2)/FiO(2), fourfold augmented bronchoalveolar lavage-retrieved volume and the increased polymorphonuclear leukocytes/bronchoalveolar cells' ratio associated with unclamping of the superior mesenteric artery. Lung tissue polymorphonuclear leukocytes count, total xanthine oxidase activity and wet-to-dry-weight ratio were also normal in these dose-treated groups. These effective regimens were also associated with longer animal survival.

CONCLUSIONS

Intratracheal methylene blue mitigates lung reperfusion injury following superior mesenteric artery clamping/unclamping at a similar magnitude as an intravenous regimen. This finding is a novel potential use of methylene blue in vivo.

Anti-inflammatory strategies for the treatment of sepsis

Sepsis leads to an overwhelming inflammatory response of the host and is usually accompanied by well-known clinical symptoms (fever, tachycardia, leukocytosis, and so on) and the accompanying systemic inflammatory response syndrome (SIRS). Accordingly, most efforts to develop treatment strategies for sepsis have focused on those designed to counteract overactivation of the inflammatory system. Despite intensive research into identifying targets in sepsis, most of the resulting clinical trials have been based on experimental data and have resulted in no beneficial effects (i.e., survival). Recombinant activated protein C (APC) represents the first treatment that has led to restricted approval for use in sepsis in the USA and worldwide. This article reviews approaches to anti-inflammatory treatment in sepsis and provides an outlook into ongoing clinical trials as well as new treatments that have not yet been evaluated in the clinical setting.

Flagellin from gram-negative bacteria is a potent mediator of acute pulmonary inflammation in sepsis

Flagellin is a recently identified bacterial product that elicits immune response via toll-like receptor 5. Here, we demonstrate that flagellin is an extraordinarily potent proinflammatory stimulus in the lung during sepsis. In vitro, flagellin triggers the production of interleukin (IL)-8 by human lung epithelial (A549) cells, with 50% of the maximal response obtained at a concentration of 2 x 10(-14) M. Flagellin also induces the expression of ICAM-1 in vitro. Intravenous administration of flagellin to mice elicited a severe acute lung inflammation that was significantly more pronounced than following lipopolysaccharide (LPS) administration. Flagellin induced a local release of proinflammatory cytokines, the accumulation of inflammatory cells, and the development of pulmonary hyperpermeability. These effects were associated with the nuclear translocation of the transcription NF-kappaB in the lung. Flagellin remained active in inducing pulmonary inflammation at doses as low as 10 ng/mouse. In the plasma of patients with sepsis, flagellin levels amounted to 7.1 +/- 0.1 ng/mL. Plasma flagellin levels showed a significant positive correlation with the lung injury score, with the alveolar-arterial oxygen difference as well as with the duration of the sepsis. Flagellin emerges as a potent trigger of acute respiratory complications in gram-negative bacterial sepsis.