Dose-dependent benefit of nitroglycerin on microcirculation of patients with severe heart failure

Local carbachol application induces oral microvascular recruitment and improves gastric tissue oxygenation during hemorrhagic shock in dogs

Introduction

Hemorrhagic shock is characterized by derangements of the gastrointestinal microcirculation. Topical therapy with nitroglycerine or iloprost improves gastric tissue oxygenation but not regional perfusion, probably due to precapillary adrenergic innervation. Therefore, this study was designed to investigate the local effect of the parasympathomimetic carbachol alone and in combination with either nitroglycerine or iloprost on gastric and oral microcirculation during hemorrhagic shock.

Methods

In a cross-over design five female foxhounds were repeatedly randomized into six experimental groups. Carbachol, or carbachol in combination with either nitroglycerine or iloprost were applied topically to the oral and gastric mucosa. Saline, nitroglycerine, or iloprost application alone served as control groups. Then, a fixed-volume hemorrhage was induced by arterial blood withdrawal followed by blood retransfusion after 1h of shock. Gastric and oral microcirculation was determined using reflectance spectrophotometry and laser Doppler flowmetry. Oral microcirculation was visualized with videomicroscopy. Statistics: 2-way-ANOVA for repeated measurements and Bonferroni post-hoc analysis (mean ± SEM; p < 0.05).

Results

The induction of hemorrhage led to a decrease of gastric and oral tissue oxygenation, that was ameliorated by local carbachol and nitroglycerine application at the gastric mucosa. The sole use of local iloprost did not improve gastric tissue oxygenation but could be supplemented by local carbachol treatment. Adding carbachol to nitroglycerine did not further increase gastric tissue oxygenation. Gastric microvascular blood flow remained unchanged in all experimental groups. Oral microvascular blood flow, microvascular flow index and total vessel density decreased during shock. Local carbachol supply improved oral vessel density during shock and oral microvascular flow index in the late course of hemorrhage.

Conclusion

The specific effect of shifting the autonomous balance by local carbachol treatment on microcirculatory variables varies between parts of the gastrointestinal tract. Contrary to our expectations, the improvement of gastric tissue oxygenation by local carbachol or nitroglycerine application was not related to increased microvascular perfusion. When carbachol is used in combination with local vasodilators, the additional effect on gastric tissue oxygenation depends on the specific drug combination. Therefore, modulation of tissue oxygen consumption, mitochondrial function or alterations in regional blood flow distribution should be investigated.

Hypoxia-induced signaling in the cardiovascular system: pathogenesis and therapeutic targets

Hypoxia, characterized by reduced oxygen concentration, is a significant stressor that affects the survival of aerobic species and plays a prominent role in cardiovascular diseases. From the research history and milestone events related to hypoxia in cardiovascular development and diseases, The "hypoxia-inducible factors (HIFs) switch" can be observed from both temporal and spatial perspectives, encompassing the occurrence and progression of hypoxia (gradual decline in oxygen concentration), the acute and chronic manifestations of hypoxia, and the geographical characteristics of hypoxia (natural selection at high altitudes). Furthermore, hypoxia signaling pathways are associated with natural rhythms, such as diurnal and hibernation processes. In addition to innate factors and natural selection, it has been found that epigenetics, as a postnatal factor, profoundly influences the hypoxic response and progression within the cardiovascular system. Within this intricate process, interactions between different tissues and organs within the cardiovascular system and other systems in the context of hypoxia signaling pathways have been established. Thus, it is the time to summarize and to construct a multi-level regulatory framework of hypoxia signaling and mechanisms in cardiovascular diseases for developing more therapeutic targets and make reasonable advancements in clinical research, including FDA-approved drugs and ongoing clinical trials, to guide future clinical practice in the field of hypoxia signaling in cardiovascular diseases.

Microcirculatory dysfunction in cardiogenic shock

Cardiogenic shock is usually defined as primary cardiac dysfunction with low cardiac output leading to critical organ hypoperfusion, and tissue hypoxia, resulting in high mortality rate between 40% and 50% despite recent advances. Many studies have now evidenced that cardiogenic shock not only involves systemic macrocirculation, such as blood pressure, left ventricular ejection fraction, or cardiac output, but also involves significant systemic microcirculatory abnormalities which seem strongly associated with the outcome. Although microcirculation has been widely studied in the context of septic shock showing heterogeneous alterations with clear evidence of macro and microcirculation uncoupling, there is now a growing body of literature focusing on cardiogenic shock states. Even if there is currently no consensus regarding the treatment of microcirculatory disturbances in cardiogenic shock, some treatments seem to show a benefit. Furthermore, a better understanding of the underlying pathophysiology may provide hypotheses for future studies aiming to improve cardiogenic shock prognosis.

Topical nitroglycerin to detect reversible microcirculatory dysfunction in patients with circulatory shock after cardiovascular surgery: an observational study

Persistent abnormalities in microcirculatory function are associated with poor clinical outcomes in patients with circulatory shock. We sought to identify patients with acutely reversible microcirculatory dysfunction using a low-dose topical nitroglycerin solution and handheld videomicroscopy during circulatory shock after cardiac surgery. Forty subjects were enrolled for the study, including 20 preoperative control and 20 post-operative patients with shock. To test whether microcirculatory dysfunction is acutely reversible during shock, the sublingual microcirculation was imaged with incident dark field microscopy before and after the application of 0.1 mL of a 1% nitroglycerin solution (1 mg/mL). Compared to the control group, patients with shock had a higher microcirculation heterogeneity index (MHI 0.33 vs. 0.12, p < 0.001) and a lower microvascular flow index (MFI 2.57 vs. 2.91, p < 0.001), total vessel density (TVD 22.47 vs. 25.90 mm/mm2, p = 0.005), proportion of perfused vessels (PPV 90.76 vs. 95.89%, p < 0.001) and perfused vessel density (PVD 20.44 vs. 24.81 mm/mm2, p < 0.001). After the nitroglycerin challenge, patients with shock had an increase in MFI (2.57 vs. 2.97, p < 0.001), TVD (22.47 vs. 27.51 mm/mm2, p < 0.009), PPV (90.76 vs. 95.91%, p < 0.001), PVD (20.44 vs. 26.41 mm/mm2, p < 0.001), venular RBC velocity (402.2 vs. 693.9 µm/s, p < 0.0004), and a decrease in MHI (0.33 vs. 0.04, p < 0.001. Thirteen of 20 patients showed a pharmacodynamic response, defined as an increase in PVD > 1.8 SD from shock baseline. Hemodynamics and vasoactive doses did not change during the 30-min study period. Our findings suggest a topical nitroglycerin challenge with handheld videomicroscopy can safely assess for localized recruitment of the microcirculatory blood flow in patients with circulatory shock and may be a useful test to identify nitroglycerin responsiveness.

Cerebral Oximetry-Monitored Nitroglycerin Infusion and Tissue Perfusion during Rewarming of Cardiopulmonary Bypass in Cardiac Surgery: A Prospective Randomized Trial

Background: Nitroglycerin facilitates microcirculation and oxygen delivery through vasodilation. The purpose of this study was to clarify the effects of nitroglycerin-induced vasodilation and potential hypotension on tissue perfusion under cerebral oximetry monitoring during rewarming in cardiopulmonary bypass. Methods: Elective cardiac surgical patients were randomly assigned to either a nitroglycerin group (n = 32) with an intravenous infusion of 1–5 mcg/kg/min or a control group (n = 31) with 0–0.1 mcg/kg/min infusion, since the initiation of rewarming. Perioperative arterial blood gas data were collected in addition to hemodynamic variables, cerebral oximetry values, urine output, and postoperative outcomes. Results: Nearly one-fifth (6/32) of patients in the nitroglycerin group experienced transient (≤5 min) profound hypotension (mean arterial blood pressure ≤40 mmHg) after the initiation of infusion. There were no significant differences between groups in terms of perioperative levels of cerebral oximetry, cardiac index, plasma glucose, lactate, bicarbonate, base excess, or post-bypass activated coagulation time. In the nitroglycerin group, urine output was nonsignificantly higher during cardiopulmonary bypass (p = 0.099) and within 8 h after surgery (p = 0.157). Perioperative transfused blood products, postoperative inotropic doses, extubation time, and intensive care unit stay were comparable for the two groups. Conclusions: Initiation of intravenous nitroglycerin infusion (at 1–5 mcg/kg/min) during rewarming in hypothermic cardiopulmonary bypass resulted in transient profound hypotension in one-fifth of patients and did not improve perioperative cerebral oxygenation, tissue perfusion, and coagulation in cardiac surgery.

Microcirculation during surgery

Throughout the long history of surgery, there has been great advancement in the hemodynamic management of surgical patients. Traditionally, hemodynamic management has focused on macrocirculatory monitoring and intervention to maintain appropriate oxygen delivery. However, even after optimization of macro-hemodynamic parameters, microcirculatory dysfunction, which is related to higher postoperative complications, occurs in some patients. Although the clinical significance of microcirculatory dysfunction has been well reported, little is known about interventions to recover microcirculation and prevent microcirculatory dysfunction. This may be at least partly caused by the fact that the feasibility of monitoring tools to evaluate microcirculation is still insufficient for use in routine clinical practice. However, considering recent advancements in these research fields, with more popular use of microcirculation monitoring and more clinical trials, clinicians may better understand and manage microcirculation in surgical patients in the future. In this review, we describe currently available methods for microcirculatory evaluation. The current knowledge on the clinical relevance of microcirculatory alterations has been summarized based on previous studies in various clinical settings. In the latter part, pharmacological and clinical interventions to improve or restore microcirculation are also presented.

Low Microcirculatory Perfused Vessel Density and High Heterogeneity are Associated With Increased Intensity and Duration of Lactic Acidosis After Cardiac Surgery with Cardiopulmonary Bypass

INTRODUCTION

Lactic acidosis after cardiac surgery with cardiopulmonary bypass is common and associated with an increase in postoperative morbidity and mortality. A number of potential causes for an elevated lactate after cardiopulmonary bypass include cellular hypoxia, impaired tissue perfusion, ischemic-reperfusion injury, aerobic glycolysis, catecholamine infusions, and systemic inflammatory response after exposure to the artificial cardiopulmonary bypass circuit. Our goal was to examine the relationship between early abnormalities in microcirculatory convective blood flow and diffusive capacity and lactate kinetics during early resuscitation in the intensive care unit. We hypothesized that patients with impaired microcirculation after cardiac surgery would have a more severe postoperative hyperlactatemia, represented by the lactate time-integral of an arterial blood lactate concentration greater than 2.0 mmol/L.

METHODS

We measured sublingual microcirculation using incident darkfield video microscopy in 50 subjects on intensive care unit admission after cardiac surgery. Serial measurements of systemic hemodynamics, blood gas, lactate, and catecholamine infusions were recorded each hour for the first 6 h after surgery. Lactate area under the curve (AUC) was calculated over the first 6 h. The lactate AUC was compared between subjects with normal and low perfused vessel density (PVD < 18 mm/mm2), high microcirculatory heterogeneity index (MHI > 0.4), and low vessel-by-vessel microvascular flow index (MFIv < 2.6).

RESULTS

Thirteen (26%) patients had a low postoperative PVD, 20 patients (40%) had a high MHI, and 26 (52%) patients had a low MFIv. Patients with low perfused vessel density had higher lactate AUC compared with subjects with a normal PVD (22.3 [9.4-31.0] vs. 2.6 [0-8.8]; P < 0.0001). Patients with high microcirculatory heterogeneity had a higher lactate AUC compared with those with a normal MHI (2.5 [0.1-8.2] vs. 13.1 [3.7-31.1]; P < 0.001). We did not find a difference in lactate AUC when comparing high and low MFIv.

CONCLUSION

Low perfused vessel density and high microcirculatory heterogeneity are associated with an increased intensity and duration of lactic acidosis after cardiac surgery with cardiopulmonary bypass.

Clinical use of peripheral perfusion parameters in septic shock

PURPOSE OF REVIEW

Current goals of resuscitation in septic shock are mainly a fixed volume of fluids and vasopressors to correct hypotension and improve tissue perfusion indicated by decreasing lactate levels.

RECENT FINDINGS

Abnormal peripheral perfusion by objective and subjective parameters are associated with increased mortality in various phases of the treatment of critically ill patients including patients with septic shock. Ongoing resuscitation in septic shock patients with normal peripheral perfusion is not associated with improved outcome, rather with increased mortality. Mitigation of fluid resuscitation by using parameters of peripheral perfusion in septic shock seems to be safe.

SUMMARY

Septic shock patients with normal peripheral perfusion represent a different clinical phenotype of patients that might benefit from limited resuscitation efforts. Parameters of peripheral perfusion could be used to guide the individualization of patients with septic shock.

Inotropic agents and vasodilator strategies for the treatment of cardiogenic shock or low cardiac output syndrome

BACKGROUND

Cardiogenic shock (CS) and low cardiac output syndrome (LCOS) are potentially life-threatening complications of acute myocardial infarction (AMI), heart failure (HF) or cardiac surgery. While there is solid evidence for the treatment of other cardiovascular diseases of acute onset, treatment strategies in haemodynamic instability due to CS and LCOS remains less robustly supported by the given scientific literature. Therefore, we have analysed the current body of evidence for the treatment of CS or LCOS with inotropic and/or vasodilating agents. This is the second update of a Cochrane review originally published in 2014.

OBJECTIVES

Assessment of efficacy and safety of cardiac care with positive inotropic agents and vasodilator agents in CS or LCOS due to AMI, HF or after cardiac surgery.

SEARCH METHODS

We conducted a search in CENTRAL, MEDLINE, Embase and CPCI-S Web of Science in October 2019. We also searched four registers of ongoing trials and scanned reference lists and contacted experts in the field to obtain further information. No language restrictions were applied.

SELECTION CRITERIA

Randomised controlled trials (RCTs) enrolling patients with AMI, HF or cardiac surgery complicated by CS or LCOS.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures according to Cochrane standards.

MAIN RESULTS

We identified 19 eligible studies including 2385 individuals (mean or median age range 56 to 73 years) and three ongoing studies. We categorised studies into 11 comparisons, all against standard cardiac care and additional other drugs or placebo. These comparisons investigated the efficacy of levosimendan versus dobutamine, enoximone or placebo; enoximone versus dobutamine, piroximone or epinephrine-nitroglycerine; epinephrine versus norepinephrine or norepinephrine-dobutamine; dopexamine versus dopamine; milrinone versus dobutamine and dopamine-milrinone versus dopamine-dobutamine. All trials were published in peer-reviewed journals, and analyses were done by the intention-to-treat (ITT) principle. Eighteen of 19 trials were small with only a few included participants. An acknowledgement of funding by the pharmaceutical industry or missing conflict of interest statements occurred in nine of 19 trials. In general, confidence in the results of analysed studies was reduced due to relevant study limitations (risk of bias), imprecision or indirectness. Domains of concern, which showed a high risk in more than 50% of included studies, encompassed performance bias (blinding of participants and personnel) and bias affecting the quality of evidence on adverse events. All comparisons revealed uncertainty on the effect of inotropic/vasodilating drugs on all-cause mortality with a low to very low quality of evidence. In detail, the findings were: levosimendan versus dobutamine (short-term mortality: RR 0.60, 95% CI 0.36 to 1.03; participants = 1701; low-quality evidence; long-term mortality: RR 0.84, 95% CI 0.63 to 1.13; participants = 1591; low-quality evidence); levosimendan versus placebo (short-term mortality: no data available; long-term mortality: RR 0.55, 95% CI 0.16 to 1.90; participants = 55; very low-quality evidence); levosimendan versus enoximone (short-term mortality: RR 0.50, 0.22 to 1.14; participants = 32; very low-quality evidence; long-term mortality: no data available); epinephrine versus norepinephrine-dobutamine (short-term mortality: RR 1.25; 95% CI 0.41 to 3.77; participants = 30; very low-quality evidence; long-term mortality: no data available); dopexamine versus dopamine (short-term mortality: no deaths in either intervention arm; participants = 70; very low-quality evidence; long-term mortality: no data available); enoximone versus dobutamine (short-term mortality RR 0.21; 95% CI 0.01 to 4.11; participants = 27; very low-quality evidence; long-term mortality: no data available); epinephrine versus norepinephrine (short-term mortality: RR 1.81, 0.89 to 3.68; participants = 57; very low-quality evidence; long-term mortality: no data available); and dopamine-milrinone versus dopamine-dobutamine (short-term mortality: RR 1.0, 95% CI 0.34 to 2.93; participants = 20; very low-quality evidence; long-term mortality: no data available). No information regarding all-cause mortality were available for the comparisons milrinone versus dobutamine, enoximone versus piroximone and enoximone versus epinephrine-nitroglycerine.

AUTHORS' CONCLUSIONS

At present, there are no convincing data supporting any specific inotropic or vasodilating therapy to reduce mortality in haemodynamically unstable patients with CS or LCOS. Considering the limited evidence derived from the present data due to a high risk of bias and imprecision, it should be emphasised that there is an unmet need for large-scale, well-designed randomised trials on this topic to close the gap between daily practice in critical care of cardiovascular patients and the available evidence. In light of the uncertainties in the field, partially due to the underlying methodological flaws in existing studies, future RCTs should be carefully designed to potentially overcome given limitations and ultimately define the role of inotropic agents and vasodilator strategies in CS and LCOS.

A flexible and physically transient electrochemical sensor for real-time wireless nitric oxide monitoring

Real-time sensing of nitric oxide (NO) in physiological environments is critically important in monitoring neurotransmission, inflammatory responses, cardiovascular systems, etc. Conventional approaches for NO detection relying on indirect colorimetric measurement or built with rigid and permanent materials cannot provide continuous monitoring and/or require additional surgical retrieval of the implants, which comes with increased risks and hospital cost. Herein, we report a flexible, biologically degradable and wirelessly operated electrochemical sensor for real-time NO detection with a low detection limit (3.97 nmol), a wide sensing range (0.01-100 μM), and desirable anti-interference characteristics. The device successfully captures NO evolution in cultured cells and organs, with results comparable to those obtained from the standard Griess assay. Incorporated with a wireless circuit, the sensor platform achieves continuous sensing of NO levels in living mammals for several days. The work may provide essential diagnostic and therapeutic information for health assessment, treatment optimization and postsurgical monitoring.

The role of arginase in the microcirculation in cardiovascular disease

In the microcirculation, the exchange of nutrients, water, gas, hormones, and waste takes place, and it is divided into the three main sections arterioles, capillaries, and venules. Disturbances in the microcirculation can be measured using surrogate parameters or be visualized either indirectly or directly.Arginase is a manganese metalloenzyme hydrolyzing L-arginine to urea and L-ornithine. It is located in different cell types, including vascular cells, but also in circulating cells such as red blood cells. A variety of pro-inflammatory factors, as well as interleukins, stimulate increased arginase expression. An increase in arginase activity consequently leads to a consumption of L-arginine needed for nitric oxide (NO) production by endothelial NO synthase. A vast body of evidence convincingly showed that increased arginase activity is associated with endothelial dysfunction in larger vessels of the vascular tree. Of note, arginase also influences the microcirculation. Arginase inhibition leads to an increase in the bioavailability of NO and reduces superoxide levels, resulting in improved endothelial function. Arginase inhibition might, therefore, be a potent treatment strategy in cardiovascular medicine. Recently, red blood cells emerged as an influential player in the development from increased arginase activity to endothelial dysfunction. As red blood cells directly interact with the microcirculation in gas exchange, this could constitute a potential link between arginase activity, endothelial dysfunction and microcirculatory disturbances.The aim of this review is to summarize recent findings revealing the role of arginase in regulating vascular function with particular emphasis on the microcirculation.

Assessment of microcirculation in cardiogenic shock

PURPOSE OF REVIEW

Adequate tissue perfusion is of utmost importance to avoid organ failure in patients with cardiogenic shock. Within the recent years, the microcirculation, defined as the perfusion of the smallest vessels, has been identified to play a crucial role. Microcirculatory changes may include capillary flow disturbances as well as changes in the density of perfused vessels. Due to the availability of new technologies to assess the microcirculation, interesting new data came up and it is the purpose of this review to summarize recent studies in the field.

RECENT FINDINGS

Nowadays, an increasing number of studies confirm parameters of the microcirculation, derived by intravital microscopy, to represent strong outcome predictors in cardiogenic shock. In addition, microcirculation as read-out parameter in innovative clinical studies has meanwhile been accepted as serious endpoint. Treatment strategies such as mechanical assist devices, blood pressure regulating agents or fluids use tissue perfusion and microcirculatory network density as targets in addition to clinical perfusion evaluation and decreasing serum lactate levels.

SUMMARY

The parameter most frequently used to detect tissue malperfusion is serum lactate. Novel, noninvasive methods to quantify microvascular perfusion have the potential to guide treatment in terms of optimizing organ perfusion and oxygenation probably paving the way for an individualized therapy.

High-dose nitroglycerin administered during rewarming preserves erythrocyte deformability in cardiac surgery with cardiopulmonary bypass

OBJECTIVE

We aimed to determine whether high-dose nitroglycerin, a nitric oxide donor, preserves erythrocyte deformability during cardiopulmonary bypass and examines the signaling pathway of nitric oxide in erythrocytes.

METHODS

In a randomized and controlled fashion, forty-two patients undergoing cardiac surgery with hypothermic cardiopulmonary bypass were allocated to high-dose (N = 21) and low-dose groups (N = 21). During rewarming period, patients were given intravenous nitroglycerin with an infusion rate 5 and 1 µg·kg^-1 ·min^-1 in high-dose and low-dose groups, respectively. Tyrosine phosphorylation level of non-muscle myosin IIA in erythrocyte membrane was used as an index of erythrocyte deformability and analyzed using immunoblotting.

RESULTS

Tyrosine phosphorylation of non-muscle myosin IIA was significantly enhanced after bypass in high-dose group (3.729 ± 1.700 folds, P = .011) but not low-dose group (1.545 ± 0.595 folds, P = .076). Phosphorylation of aquaporin 1, vasodilator-stimulated phosphoprotein, and focal adhesion kinase in erythrocyte membrane was also upregulated in high-dose group after bypass. Besides, plasma nitric oxide level was highly correlated with fold change of non-muscle myosin IIA phosphorylation (Pearson's correlation coefficient .871).

CONCLUSIONS

High-dose nitroglycerin administered during cardiopulmonary bypass improves erythrocyte deformability through activating phosphorylation of aquaporin 1, vasodilator-stimulated phosphoprotein, and focal adhesion kinase in erythrocytes.

Old and New Drugs for Treatment of Advanced Heart Failure

BACKGROUND

Advanced heart failure (HF) is a progressive disease with high mortality and limited medical therapeutic options. Long-term mechanical circulatory support and heart transplantation remain goldstandard treatments for these patients; however, access to these therapies is limited by the advanced age and multiple comorbidities of affected patients, as well as by the limited number of organs available.

METHODS

Traditional and new drugs available for the treatment of advanced HF have been researched.

RESULTS

To date, the cornerstone for the treatment of patients with advanced HF remains water restriction, intravenous loop diuretic therapy and inotropic support. However, many patients with advanced HF experience loop diuretics resistance and alternative therapeutic strategies to overcome this problem have been developed, including sequential nephron blockade or use of the hypertonic saline solution in combination with high-doses of furosemide. As classic inotropes augment myocardial oxygen consumption, new promising drugs have been introduced, including levosimendan, istaroxime and omecamtiv mecarbil. However, pharmacological agents still remain mainly short-term or palliative options in patients with acute decompensation or excluded from mechanical therapy.

CONCLUSION

Traditional drugs, especially when administered in combination, and new medicaments represent important therapeutic options in advanced HF. However, their impact on prognosis remains unclear. Large trials are necessary to clarify their therapeutic potential and prognostic role in these fragile patients.

Recent advances in bedside microcirculation assessment in critically ill patients

Parameters related to macrocirculation, such as the mean arterial pressure, central venous pressure, cardiac output, mixed venous saturation and central oxygen saturation, are commonly used in the hemodynamic assessment of critically ill patients. However, several studies have shown that there is a dissociation between these parameters and the state of microcirculation in this group of patients. Techniques that allow direct viewing of the microcirculation are not completely disseminated, nor are they incorporated into the clinical management of patients in shock. The numerous techniques developed for microcirculation assessment include clinical assessment (e.g., peripheral perfusion index and temperature gradient), laser Doppler flowmetry, tissue oxygen assessment electrodes, videomicroscopy (orthogonal polarization spectral imaging, sidestream dark field imaging or incident dark field illumination) and near infrared spectroscopy. In the near future, the monitoring and optimization of tissue perfusion by direct viewing and microcirculation assessment may become a goal to be achieved in the hemodynamic resuscitation of critically ill patients.

Inotropic agents and vasodilator strategies for the treatment of cardiogenic shock or low cardiac output syndrome

BACKGROUND

Cardiogenic shock (CS) and low cardiac output syndrome (LCOS) as complications of acute myocardial infarction (AMI), heart failure (HF) or cardiac surgery are life-threatening conditions. While there is a broad body of evidence for the treatment of people with acute coronary syndrome under stable haemodynamic conditions, the treatment strategies for people who become haemodynamically unstable or develop CS remain less clear. We have therefore summarised here the evidence on the treatment of people with CS or LCOS with different inotropic agents and vasodilative drugs. This is the first update of a Cochrane review originally published in 2014.

OBJECTIVES

To assess efficacy and safety of cardiac care with positive inotropic agents and vasodilator strategies in people with CS or LCOS due to AMI, HF or cardiac surgery.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase and CPCI-S Web of Science in June 2017. We also searched four registers of ongoing trials and scanned reference lists and contacted experts in the field to obtain further information. No language restrictions were applied.

SELECTION CRITERIA

Randomised controlled trials in people with myocardial infarction, heart failure or cardiac surgery complicated by cardiogenic shock or LCOS.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We identified 13 eligible studies with 2001 participants (mean or median age range 58 to 73 years) and two ongoing studies. We categorised studies into eight comparisons, all against cardiac care and additional other active drugs or placebo. These comparisons investigated the efficacy of levosimendan versus dobutamine, enoximone or placebo, epinephrine versus norepinephrine-dobutamine, amrinone versus dobutamine, dopexamine versus dopamine, enoximone versus dopamine and nitric oxide versus placebo.All trials were published in peer-reviewed journals, and analysis was done by the intention-to-treat (ITT) principle. Twelve of 13 trials were small with few included participants. Acknowledgement of funding by the pharmaceutical industry or missing conflict of interest statements emerged in five of 13 trials. In general, confidence in the results of analysed studies was reduced due to serious study limitations, very serious imprecision or indirectness. Domains of concern, which show a high risk of more than 50%, include performance bias (blinding of participants and personnel) and bias affecting the quality of evidence on adverse events.Levosimendan may reduce short-term mortality compared to a therapy with dobutamine (RR 0.60, 95% CI 0.37 to 0.95; 6 studies; 1776 participants; low-quality evidence; NNT: 16 (patients with moderate risk), NNT: 5 (patients with CS)). This initial short-term survival benefit with levosimendan vs. dobutamine is not confirmed on long-term follow up. There is uncertainty (due to lack of statistical power) as to the effect of levosimendan compared to therapy with placebo (RR 0.48, 95% CI 0.12 to 1.94; 2 studies; 55 participants, very low-quality evidence) or enoximone (RR 0.50, 95% CI 0.22 to 1.14; 1 study; 32 participants, very low-quality evidence).All comparisons comparing other positive inotropic, inodilative or vasodilative drugs presented uncertainty on their effect on short-term mortality with very low-quality evidence and based on only one RCT. These single studies compared epinephrine with norepinephrine-dobutamine (RR 1.25, 95% CI 0.41 to 3.77; 30 participants), amrinone with dobutamine (RR 0.33, 95% CI 0.04 to 2.85; 30 participants), dopexamine with dopamine (no in-hospital deaths from 70 participants), enoximone with dobutamine (two deaths from 40 participants) and nitric oxide with placebo (one death from three participants).

AUTHORS' CONCLUSIONS

Apart from low quality of evidence data suggesting a short-term mortality benefit of levosimendan compared with dobutamine, at present there are no robust and convincing data to support a distinct inotropic or vasodilator drug-based therapy as a superior solution to reduce mortality in haemodynamically unstable people with cardiogenic shock or LCOS.Considering the limited evidence derived from the present data due to a generally high risk of bias and imprecision, it should be emphasised that there remains a great need for large, well-designed randomised trials on this topic to close the gap between daily practice in critical care medicine and the available evidence. It seems to be useful to apply the concept of 'early goal-directed therapy' in cardiogenic shock and LCOS with early haemodynamic stabilisation within predefined timelines. Future clinical trials should therefore investigate whether such a therapeutic concept would influence survival rates much more than looking for the 'best' drug for haemodynamic support.

[Management of cardiogenic shock: Results from a survey in France and Belgium]

PURPOSE

Physician survey on cardiogenic shock management; recommendations for the management of patients with cardiogenic shock are based mostly on experts' opinion.

METHODS

Overall 1585 emails were sent to "senior" intensive care physicians from France and Belgium from September 2014 to march 2015. Response rate was 10% (157 respondents). Agreement was assessed based on RAND/UCLA methodology.

RESULTS

Continuous monitoring of cardiac output, vascular filling, noninvasive ventilation were deemed appropriate. The use of systematic diuretics and dopamine seemed inappropriate. There was a strong agreement to use dobutamine as inotropic drug in first intention. The use of noradrenaline and adrenaline was considered appropriate. There was a strong agreement to use mechanical circulatory support, in particular extracorporeal life support, in refractory cardiogenic shock. Only 25% of responders felt that there are criteria of refractory cardiogenic shock. Concerning the objectives of systolic, diastolic and mean blood pressure, 95% of the responses were in the range between 70 to 100, 30 to 50, and 55 to 65mmHg, respectively. The target of SvO₂ was between 55% and 75%, and cardiac index between 1.5 and 3L/min/m² for 95% of responders. There was a strong agreement to maintain hemoglobin between 7 and 9.9g/dL.

CONCLUSION

Based on our physician survey, we found an agreement in vascular filling and early enteral nutrition. Dobutamine and noradrenaline should be the preferred drugs, but not dopamine. Mechanical circulatory support (preferably with extracorporeal support) should be restricted to refractory cardiogenic shock. Those responses differed slightly from experts' opinion, available in terms of recommendations.

Evaluation of the microcirculation in critically ill patients

Adequate monitoring of patients on intensive care units is of highest priority to provide optimal treatment and to detect patients at risk. Within recent years the microcirculation became more and more attention due to its central importance for the outcome of patients. Microcirculatory disorders may include capillary flow disturbances as well as changes in the density of perfused vessels. In the clinical setting, the most often used parameter to detect alterations in the microcirculation is serum lactate. Since this parameter is characterized by major limitations, other strategies including non-invasive methods to quantify microvascular perfusion have been developed. A successful surveillance of the microcirculation in the individual patient may guide diagnostic and treatment strategies in order to optimize organ perfusion and oxygenation, subsequently leading to an individualized therapy. Intravital microscopy has been used to stratify patients at risk and to predict patients' outcome. The aim of this review is to evaluate clinical correlates of microcirculatory disorders as well as giving an overview of newer diagnostic devices that may directly or indirectly evaluate the microcirculation and are available for use in critically ill patients.

A guide to human in vivo microcirculatory flow image analysis

Various noninvasive microscopic camera technologies have been used to visualize the sublingual microcirculation in patients. We describe a comprehensive approach to bedside in vivo sublingual microcirculation video image capture and analysis techniques in the human clinical setting. We present a user perspective and guide suitable for clinical researchers and developers interested in the capture and analysis of sublingual microcirculatory flow videos. We review basic differences in the cameras, optics, light sources, operation, and digital image capture. We describe common techniques for image acquisition and discuss aspects of video data management, including data transfer, metadata, and database design and utilization to facilitate the image analysis pipeline. We outline image analysis techniques and reporting including video preprocessing and image quality evaluation. Finally, we propose a framework for future directions in the field of microcirculatory flow videomicroscopy acquisition and analysis. Although automated scoring systems have not been sufficiently robust for widespread clinical or research use to date, we discuss promising innovations that are driving new development.

Microcirculatory and mitochondrial hypoxia in sepsis, shock, and resuscitation

After shock, persistent oxygen extraction deficit despite the apparent adequate recovery of systemic hemodynamic and oxygen-derived variables has been a source of uncertainty and controversy. Dysfunction of oxygen transport pathways during intensive care underlies the sequelae that lead to organ failure, and the limitations of techniques used to measure tissue oxygenation in vivo have contributed to the lack of progress in this area. Novel techniques have provided detailed quantitative insight into the determinants of microcirculatory and mitochondrial oxygenation. These techniques, which are based on the oxygen-dependent quenching of phosphorescence or delayed luminescence are briefly reviewed. The application of these techniques to animal models of shock and resuscitation revealed the heterogeneous nature of oxygen distributions and the alterations in oxygen distribution in the microcirculation and in mitochondria. These studies identified functional shunting in the microcirculation as an underlying cause of oxygen extraction deficit observed in states of shock and resuscitation. The translation of these concepts to the bedside has been enabled by our development and clinical introduction of hand-held microscopy. This tool facilitates the direct observation of the microcirculation and its alterations at the bedside under the conditions of shock and resuscitation. Studies identified loss of coherence between the macrocirculation and the microcirculation, in which resuscitation successfully restored systemic circulation but did not alleviate microcirculatory perfusion alterations. Various mechanisms responsible for these alterations underlie the loss of hemodynamic coherence during unsuccessful resuscitation procedures. Therapeutic resolution of persistent heterogeneous microcirculatory alterations is expected to improve outcomes in critically ill patients.

Lactate as a hemodynamic marker in the critically ill

PURPOSE OF REVIEW

An early quantitative resuscitation strategy improves outcome in critically ill patients. The hemodynamic endpoints of such a strategy have been a topic of debate in the literature. This review focuses on the use of lactate as a marker for risk stratification, lactate clearance as a hemodynamic endpoint, and its use compared to mixed venous oxygenation as a resuscitation goal.

RECENT FINDINGS

Lactate clearance is associated with improved outcome across several cohorts of critically ill patients. Lactate levels and central venous oxygen saturations are frequently discordant. Targeting lactate clearance as part of a quantitative resuscitation strategy may be as effective as targeting central venous oxygen saturation.

SUMMARY

Resuscitation of the critically ill patient should be aimed at the reversal of tissue hypoxia. The use of lactate as a hemodynamic marker and resuscitation endpoint makes physiologic sense, and is supported by the recent data. The use of lactate clearance versus other traditional endpoints of resuscitation, such as mixed venous oxygen saturation, should be based on the clinical characteristics and response of the individual patient.

Increased arginase levels contribute to impaired perfusion after cardiopulmonary resuscitation

OBJECTIVES

The postcardiac arrest syndrome occurs after global hypoxia leading to microcirculatory impairment. Nitric oxide (NO) is a key molecule regulating microvascular function. The enzyme arginase has been suggested to modulate microvascular function by regulating NO metabolism. Therefore, we investigated whether arginase increases following global hypoxia and resuscitation and tested whether arginase inhibition influences altered microcirculation in resuscitated patients.

METHODS

To determine the effect of global hypoxia on circulating arginase levels, fourteen healthy subjects were exposed to hypoxia in a normobaric hypoxia chamber (FiO² = 9·9%). In addition, 31 resuscitated patients were characterized clinically, and arginase 1 was measured on days 1 and 3. In eight resuscitated patients, a microcirculatory analysis was performed using a sidestream darkfield microcirculation camera. Perfused capillary density (PCD) was recorded before and after sublingual incubation of N-omega-hydroxy-nor-l-arginine (nor-NOHA) alone or together with the NOS inhibitor NG-monomethyl-l-arginine (l-NMMA).

RESULTS

Circulating arginase 1 levels increased in healthy volunteers following global hypoxia in the hypoxic chamber (P < 0·01). In addition, arginase 1 levels were higher on day 1 (69·1 ± 83·3 ng/mL) and on day 3 (44·2 ± 65·6 ng/mL) after resuscitation than in control subjects (P < 0·001). Incubation of the sublingual mucosa with nor-NOHA increased microcirculatory perfusion (P < 0·001). This effect was inhibited by co-incubation with K-NMMA.

CONCLUSIONS

Circulating arginase 1 levels are increased following exposure to global hypoxia and in patients who have been successfully resuscitated after cardiac arrest. Topical arginase inhibition improves microcirculatory perfusion following resuscitation. This is of potential therapeutic importance for the postcardiac arrest syndrome.

Conventional hemodynamic resuscitation may fail to optimize tissue perfusion: an observational study on the effects of dobutamine, enoximone, and norepinephrine in patients with acute myocardial infarction complicated by cardiogenic shock

AIM

To investigate the effects of inotropic agents on parameters of tissue perfusion in patients with cardiogenic shock.

METHODS AND RESULTS

Thirty patients with cardiogenic shock were included. Patients received dobutamine, enoximone, or norepinephrine. We performed hemodynamic measurements at baseline and after titration of the inotropic agent until cardiac index (CI) ≥ 2.5 L.min-1.m(-2) or mixed-venous oxygen saturation (SvO2) ≥ 70% (dobutamine or enoximone), and mean arterial pressure (MAP) ≥ 70 mmHg (norepinephrine). As parameters of tissue perfusion, we measured central-peripheral temperature gradient (delta-T) and sublingual perfused capillary density (PCD). All patients reached predefined therapeutic targets. The inotropes did not significantly change delta-T. Dobutamine did not change PCD. Enoximone increased PCD (9.1 [8.9-10.2] vs. 11.4 [8.4-13.9] mm.mm(-2); p<0.05), and norepinephrine tended to decrease PCD (9.8 [8.5-11.9] vs. 8.8 [8.2-9.6] mm.mm-2, p = 0.08). Fifteen patients (50%) died within 30 days after admission. Patients who had low final PCD (≤ 10.3 mm.mm-2; 64%) were more likely to die than patients who had preserved PCD (>10.3 mm.mm(-2); mortality 72% vs. 17%, p = 0.003).

CONCLUSION

This study demonstrates the effects of commonly used inotropic agents on parameters of tissue perfusion in patients with cardiogenic shock. Despite hemodynamic optimization, tissue perfusion was not sufficiently restored in most patients. In these patients, mortality was high. Interventions directed at improving microcirculation may eventually help bridging the gap between improved hemodynamics and dismal patient outcome in cardiogenic shock.

Nitroglycerin reverts clinical manifestations of poor peripheral perfusion in patients with circulatory shock

INTRODUCTION

Recent clinical studies have shown a relationship between abnormalities in peripheral perfusion and unfavorable outcome in patients with circulatory shock. Nitroglycerin is effective in restoring alterations in microcirculatory blood flow. The aim of this study was to investigate whether nitroglycerin could correct the parameters of abnormal peripheral circulation in resuscitated circulatory shock patients.

METHODS

This interventional study recruited patients who had circulatory shock and who persisted with abnormal peripheral perfusion despite normalization of global hemodynamic parameters. Nitroglycerin started at 2 mg/hour and doubled stepwise (4, 8, and 16 mg/hour) each 15 minutes until an improvement in peripheral perfusion was observed. Peripheral circulation parameters included capillary refill time (CRT), skin-temperature gradient (Tskin-diff), perfusion index (PI), and tissue oxygen saturation (StO2) during a reactive hyperemia test (RincStO2). Measurements were performed before, at the maximum dose, and after cessation of nitroglycerin infusion. Data were analyzed by using linear model for repeated measurements and are presented as mean (standard error).

RESULTS

Of the 15 patients included, four patients (27%) responded with an initial nitroglycerin dose of 2 mg/hour. In all patients, nitroglycerin infusion resulted in significant changes in CRT, Tskin-diff, and PI toward normal at the maximum dose of nitroglycerin: from 9.4 (0.6) seconds to 4.8 (0.3) seconds (P < 0.05), from 3.3 °C (0.7 °C) to 0.7 °C (0.6 °C) (P < 0.05), and from [log] -0.5% (0.2%) to 0.7% (0.1%) (P < 0.05), respectively. Similar changes in StO2 and RincStO2 were observed: from 75% (3.4%) to 84% (2.7%) (P < 0.05) and 1.9%/second (0.08%/second) to 2.8%/second (0.05%/second) (P < 0.05), respectively. The magnitude of changes in StO2 was more pronounced for StO2 of less than 75%: 11% versus 4%, respectively (P < 0.05).

CONCLUSIONS

Dose-dependent infusion of nitroglycerin reverted abnormal peripheral perfusion and poor tissue oxygenation in patients following circulatory shock resuscitation. Individual requirements of nitroglycerin dose to improve peripheral circulation vary between patients. A simple and fast physical examination of peripheral circulation at the bedside can be used to titrate nitroglycerin infusion.

New insights into the pathophysiology of cardiogenic shock: the role of the microcirculation

PURPOSE OF REVIEW

The ultimate goal of therapy for cardiogenic shock is to restore microcirculatory function and thereby restore the oxygen supply to sustain cellular function. Therapeutic measures mainly focus on improving pressure-derived macrocirculatory parameters. However, it is increasingly clear that to achieve significant progress in treatment, microcirculatory physiopathological mechanisms must be considered.

RECENT FINDINGS

Microcirculatory function deteriorated during cardiogenic shock and improved after treatment. Postcardiogenic shock microcirculatory disturbances, both myocardial and peripheral, were a prognostic factor for the long-term outcome. Hypothermia, whether pharmacologically or physically induced, improved postresuscitation myocardial and cerebral function, an effect associated with improved postresuscitation microcirculation. The impact of cardiogenic shock on cerebral and myocardial microcirculation could be evaluated with MRI. In severe heart failure, pharmacological interventions improved microcirculation. An assessment of the microcirculation was often performed using handheld video microscopy for direct observation of the sublingual microcirculation, which proved to be useful for evaluating the effects of interventions during cardiogenic shock. A large multicenter study on critically ill patients is now being conducted using this technique.

SUMMARY

Cardiogenic shock induces microcirculatory disorders that can be monitored and influenced in various manners, both pharmacologically and physically. In addition to global hemodynamic optimization, interventions must also ameliorate the microcirculation.

Inotropic agents and vasodilator strategies for acute myocardial infarction complicated by cardiogenic shock or low cardiac output syndrome

BACKGROUND

The recently published German-Austrian S3 Guideline for the treatment of infarct related cardiogenic shock (CS) revealed a lack of evidence for all recommended therapeutic measures.

OBJECTIVES

To determine the effects in terms of efficacy, efficiency and safety of cardiac care with inotropic agents and vasodilator strategies versus placebo or against each other for haemodynamic stabilisation following surgical treatment, interventional therapy (angioplasty, stent implantation) and conservative treatment (that is no revascularization) on mortality and morbidity in patients with acute myocardial infarction (AMI) complicated by CS or low cardiac output syndrome (LCOS).

SEARCH METHODS

We searched CENTRAL, MEDLINE (Ovid), EMBASE (Ovid) and ISI Web of Science, registers of ongoing trials and proceedings of conferences in January 2013. Reference lists were scanned and experts in the field were contacted to obtain further information. No language restrictions were applied.

SELECTION CRITERIA

Randomised controlled trials in patients with AMI complicated by CS or LCOS.

DATA COLLECTION AND ANALYSIS

Data collection and analysis were performed according to the published protocol. All trials were analysed individually. Hazard ratios (HRs) and odds ratios with 95% confidence intervals (CI) were extracted but not pooled because of high heterogeneity between the control group interventions.

MAIN RESULTS

Four eligible, very small studies were identified from a total of 4065 references. Three trials with high overall risk of bias compared levosimendan to standard treatment (enoximone or dobutamine) or placebo. Data from a total of 63 participants were included in our comparisons, 31 were treated with levosimendan and 32 served as controls. Levosimendan showed an imprecise survival benefit in comparison with enoximone based on a very small trial with 32 participants (HR 0.33; 95% CI 0.11 to 0.97). Results from the other similarly small trials were too imprecise to provide any meaningful information about the effect of levosimendan in comparison with dobutamine or placebo. Only small differences in haemodynamics, length of hospital stay and the frequency of major adverse cardiac events or adverse events overall were found between study groups.Only one small randomised controlled trial with three participants was found for vasodilator strategies (nitric oxide gas versus placebo) in AMI complicated by CS or LCOS. This study was too small to draw any conclusions on the effects on our key outcomes.

AUTHORS' CONCLUSIONS

At present there are no robust and convincing data to support a distinct inotropic or vasodilator drug based therapy as a superior solution to reduce mortality in haemodynamically unstable patients with CS or low cardiac output complicating AMI.

Pathophysiology of microcirculatory dysfunction and the pathogenesis of septic shock

Multiple experimental and human trials have shown that microcirculatory alterations are frequent in sepsis. In this review, we discuss the various mechanisms that are potentially involved in their development and the implications of these alterations. Endothelial dysfunction, impaired inter-cell communication, altered glycocalyx, adhesion and rolling of white blood cells and platelets, and altered red blood cell deformability are the main mechanisms involved in the development of these alterations. Microcirculatory alterations increase the diffusion distance for oxygen and, due to the heterogeneity of microcirculatory perfusion in sepsis, may promote development of areas of tissue hypoxia in close vicinity to well-oxygenated zones. The severity of microvascular alterations is associated with organ dysfunction and mortality. At this stage, therapies to specifically target the microcirculation are still being investigated.

Lactate and lactate clearance in acute cardiac care patients

Hyperlactataemia is commonly used as a diagnostic and prognostic tool in intensive care settings. Recent studies documented that serial lactate measurements over time (or lactate clearance), may be clinically more reliable than lactate absolute value for risk stratification in different pathological conditions. While the negative prognostic role of hyperlactataemia in several critical ill diseases (such as sepsis and trauma) is well established, data in patients with acute cardiac conditions (i.e. acute coronary syndromes) are scarce and controversial. The present paper provides an overview of the current available evidence on the clinical role of lactic acid levels and lactate clearance in acute cardiac settings (acute coronary syndromes, cardiogenic shock, cardiac surgery), focusing on its prognostic role.

Nitric oxide modulation as a therapeutic strategy in heart failure

Nitric oxide (NO) is recognized as one of the most important cardiovascular signaling molecules, with multiple regulatory effects on myocardial and vascular tissue as well as on other tissues and organ systems. With the growth in understanding of the range and mechanisms of NO effects on the cardiovascular system, it is now possible to consider pharmaceutical interventions that directly target NO or key steps in NO effector pathways. This article reviews aspects of the cardiovascular effects of NO, abnormalities in NO regulation in heart failure, and clinical trials of drugs that target specific aspects of NO signaling pathways.

Clinical review: Clinical imaging of the sublingual microcirculation in the critically ill--where do we stand?

A growing body of evidence exists associating depressed microcirculatory function and morbidity and mortality in a wide array of clinical scenarios. It has been suggested that volume replacement therapy using fluids and/or blood in combination with vasoactive agents to modulate macro- and microvascular perfusion might be essential for resuscitation of severely septic patients. Even after interventions effectively optimizing macrocirculatory hemodynamics, however, high mortality rates still persist in critically ill and especially in septic patients. Therefore, rather than limiting therapy to macrocirculatory targets alone, microcirculatory targets could be incorporated to potentially reduce mortality rates in these critically ill patients. In the present review we first provide a brief history of clinical imaging of the microcirculation and describe how microcirculatory imaging has been of prognostic value in intensive care patients. We then give an overview of therapies potentially improving the microcirculation in critically ill patients and propose a clinical trial aimed at demonstrating that therapy targeting improvement of the microcirculation results in improved organ function in patients with severe sepsis and septic shock. We end with some recent technological advances in clinical microcirculatory image acquisition and analysis.

Lactate clearance in cardiogenic shock following ST elevation myocardial infarction: a pilot study

BACKGROUND

Recent studies documented that serial lactate measurements over time may be clinically more reliable than lactate absolute value for risk stratification. The aim of the present investigation was to assess the role of lactate clearance in predicting early death in cardiogenic shock (CS) following ST-elevation myocardial infarction (STEMI) submitted to primary percutaneous coronary intervention (PCI).

METHODS

51 consecutive patients with CS following STEMI were prospectively enrolled. Lactate was measured in Intensive Cardiac Care Unit (ICCU) on admission and on the twelfth hour. Logistic regression analysis was performed to identify the independent predictors for in-ICCU mortality. Receiver operating characteristic (ROC) curve was constructed in order to identify cut-off for admission lactate and for 12-h lactate clearance in relation to in-ICCU mortality. Follow-up survival rate were investigated by Kaplan-Meier curves.

RESULTS

At 12 h from admission, lactate clearance was higher in survivors (P=0.013). A higher in-ICCU mortality was observed in patients with 12 hours lactate clearance<10% (P=0.002). At follow up, patients with 12-h lactate clearance<10% showed a significantly lower survival rate.

CONCLUSIONS

In patients with CS following STEMI, 12-h lactate clearance<10% identifies a subset of patients at higher risk for death at short and long-term.

Targeting the microcirculation in resuscitation of acutely unwell patients

PURPOSE OF REVIEW

The ultimate goals of hemodynamic therapy in acutely unwell patients are to restore effective tissue perfusion and oxygen delivery to maintain cellular metabolism. Optimization of systemic hemodynamics may improve the time course of microcirculatory dysfunction and eventually the patient's outcome. However, relationships between systemic hemodynamics and microcirculatory changes during resuscitation are complex and underperfused microcirculation may persist, despite restored macrohemodynamics. Thus, targeting the microcirculation is a logical goal to obtain an adequate resuscitation.

RECENT FINDINGS

The impact of systemic interventions such as fluid resuscitation, vasopressor therapy, and transfusion has been evaluated on microcirculatory perfusion in septic-shock patients. It demonstrated inconstant improvement according to time-course evolution of the underlying pathology with interindividual variability. Thus, therapy targeting the microcirculation should be adapted to individual microcirculatory monitoring. Specific therapy with nitroglycerin did not promote microcirculation in septic shock but was associated with microcirculatory improvement in cardiogenic shock.

SUMMARY

Microcirculatory hemodynamics have to be restored as soon as possible during the early phase of the management of acutely unwell patients. Future trials should test whether microcirculation-guided strategy could better improve organ dysfunction than global hemodynamic-guided strategy. An optimal resuscitation has to restore the systematic hemodynamics and make sure of the quality of the microcirculation.

Sublingual tissue perfusion improves during emergency treatment of acute decompensated heart failure

OBJECTIVES

The aim of this study was to measure sublingual perfused capillary density (PCD) to assess sublingual microvascular perfusion during emergency department (ED) treatment of acute decompensated heart failure (ADHF).

METHODS

This prospective, observational study enrolled ED patients with ADHF, measuring pre- and post-ED treatment PCD. Sidestream dark-field imaging was analyzed by 3 investigators blinded to patient identifiers and time points. Patient demographics, ADHF etiology, serum brain natriuretic peptide, and hemoglobin were measured along with a visual analogue scale (VAS), which assessed patient baseline characteristics and response to ED treatment. A paired t test analyzed changes in PCD, mean arterial pressure (MAP), and patient assessment. Interrater variability was assessed with an intraclass correlation coefficient (ICC), with a P value <.05 considered significant for all testing.

RESULTS

Thirty-six patients were enrolled with a mean time between pretreatment and posttreatment PCD (±SD) of 138 ± 59 minutes and a hospital length of stay of 4.0 ± 4.1 days. During this time, PCD increased (difference, 1.3 mm/mm(2); 95% confidence interval, 0.4-2.1; P = .004), as did the MAP (P = .002), patient VAS score (P < .001), and observer VAS score (P < .001). There was no correlation between the change in PCD and time (R(2) = .016, P = .47), MAP (R(2) = .013, P = .54), or VAS scores. The ICC was 0.954.

CONCLUSIONS

Sublingual tissue perfusion is diminished in ADHF but increases with treatment. It may represent a quantitative way to evaluate ADHF in the ED setting.

Microcirculatory alterations: potential mechanisms and implications for therapy

Multiple experimental and human trials have shown that microcirculatory alterations are frequent in sepsis. In this review, we discuss the characteristics of these alterations, the various mechanisms potentially involved, and the implications for therapy. Sepsis-induced microvascular alterations are characterized by a decrease in capillary density with an increased number of stopped-flow and intermittent-flow capillaries, in close vicinity to well-perfused capillaries. Accordingly, the surface available for exchange is decreased but also is highly heterogeneous. Multiple mechanisms may contribute to these alterations, including endothelial dysfunction, impaired inter-cell communication, altered glycocalyx, adhesion and rolling of white blood cells and platelets, and altered red blood cell deformability. Given the heterogeneous nature of these alterations and the mechanisms potentially involved, classical hemodynamic interventions, such as fluids, red blood cell transfusions, vasopressors, and inotropic agents, have only a limited impact, and the microcirculatory changes often persist after resuscitation. Nevertheless, fluids seem to improve the microcirculation in the early phase of sepsis and dobutamine also can improve the microcirculation, although the magnitude of this effect varies considerably among patients. Finally, maintaining a sufficient perfusion pressure seems to positively influence the microcirculation; however, which mean arterial pressure levels should be targeted remains controversial. Some trials using vasodilating agents, especially nitroglycerin, showed promising initial results but they were challenged in other trials, so it is difficult to recommend the use of these agents in current practice. Other agents can markedly improve the microcirculation, including activated protein C and antithrombin, vitamin C, or steroids. In conclusion, microcirculatory alterations may play an important role in the development of sepsis-related organ dysfunction. At this stage, therapies to target microcirculation specifically are still being investigated.