The spectrum of cardiovascular effects of dobutamine - from healthy subjects to septic shock patients

The role of myocardial blood volume in the pathophysiology of angina with non-obstructed coronary arteries: The MICORDIS study

BACKGROUND

Angina with Non-Obstructed Coronary Arteries (ANOCA) involves abnormal vasomotor responses. While reduced coronary flow is an established contributor to myocardial hypoxia, myocardial blood volume (MBV) independently regulates myocardial oxygen uptake but its role in ANOCA remains unclear.

OBJECTIVES

We hypothesized that reduced MBV contributes to ANOCA, and associates with insulin resistance in ANOCA.

METHODS

MBV in ANOCA patients was compared to age- and sex-matched healthy controls. ANOCA patients underwent coronary angiography with invasive coronary function testing (CFT) to identify vasospasm and coronary microvascular dysfunction. In all subjects MBV was quantified at baseline, during hyperinsulinemia and during dobutamine-induced stress using myocardial contrast echocardiography (MCE). The hyperinsulinemic-euglycemic clamp was used to assess insulin resistance.

RESULTS

Twenty-eight ANOCA patients (21% men, 56.8 ± 8.6 years) and 28 healthy controls (21% men, 56.5 ± 7.0 years) were included. During CFT 11% of patients showed epicardial vasospasm, 39% microvascular vasospasm, 25% coronary microvascular dysfunction, and 11% of patients had a negative CFT. ANOCA patients had significant lower insulin-sensitivity (p < 0.01). During MCE, ANOCA patients showed a significantly lower MBV at baseline (0.388 vs 0.438 mL/mL, p = 0.04), during hyperinsulinemia (0.395 vs 0.447 mL/mL, p = 0.02), and during dobutamine-induced stress (0.401 vs 0.476 mL/mL, p = 0.030).

CONCLUSIONS

In ANOCA patients MBV is diminished at baseline, during hyperinsulinemia and dobutamine-induced stress in the absence of differences in microvascular recruitment. These findings support the presence of capillary rarefaction in ANOCA patients. ANOCA patients showed metabolic insulin resistance, but insulin did not acutely alter myocardial perfusion.

Therapeutic efficacy of adrenergic agents on systemic and spinal hemodynamics in an acute cervical spinal cord injury rodent model

BACKGROUND

Cervical spinal cord injury usually results in cardiorespiratory dysfunctions due to interruptions of the bulbospinal pathways innervating the cervical phrenic motoneurons and thoracic sympathetic preganglionic neurons.

PURPOSE

The present study aimed to evaluate the therapeutic effects of adrenergic agents on systemic and spinal hemodynamics during acute cervical spinal cord injury.

STUDY DESIGN

In vivo animal study.

METHODS

The cardiorespiratory function and spinal cord blood flow and oxygenation level were monitored in response to cervical spinal cord contusion and intravenous infusion of three types of adrenergic agents (phenylephrine, dobutamine, and norepinephrine).

RESULTS

Cervical spinal cord contusion resulted in immediate reduction of respiratory airflow, arterial blood pressure, and spinal cord blood flow. The arterial blood pressure and spinal cord blood flow remained lower than the preinjury value in contused animals infused with saline at 60 min postinjury. Infusion of phenylephrine (500, 1000, and 2000 μg/kg) and norepinephrine (125, 250, and 500 μg/kg) significantly increased the arterial blood pressure, while only norepinephrine augmented the spinal cord blood flow. Conversely, dobutamine (1000 and 2000 μg/kg) reduced both arterial blood pressure and spinal cord blood flow. Notably, administration of adrenergic agents tended to increase spinal cord hemorrhage in contused animals.

CONCLUSIONS

Infusion of norepinephrine can effectively maintain the blood pressure and improve spinal cord blood flow during acute spinal cord injury.

CLINICAL SIGNIFICANCE

Norepinephrine may be a superior medicine for hemodynamic management; however, the potential hemorrhage should be considered when utilizing the vasopressor to regulate systemic and spinal hemodynamics at the acute injured stage.

Exercise Preconditioning Preserves Cardiac Function and Enhances Cardiac Recovery Following Dobutamine Stimulation in Doxorubicin-Treated Rat Hearts

ABSTRACT

Exercise preconditioning has been shown to protect against doxorubicin (DOX)-induced cardiac dysfunction when hearts are maintained under resting conditions. However, it is unclear whether this exercise-induced protective effect is maintained when the heart is challenged with the β 1 -adrenergic receptor agonist dobutamine (DOB), which mimics acute exercise stress. Fischer 344 rats were randomly assigned to sedentary (SED) or voluntary wheel running (WR) groups for 10 weeks. At week 11, rats were treated with either 15 mg/kg DOX or saline. Five days later, ex vivo cardiac function was assessed using an isolated working heart model at baseline, during the infusion of 7.5 μg·kg -1 ·min -1 DOB, and during recovery. DOB infusion significantly increased left ventricular developed pressure (LVDP), maximal (dP/dt max ) and minimal (dP/dt min ) rate of left ventricular pressure development, and heart rate in all groups ( P < 0.05). SED + DOX also showed a lower baseline and recovery LVDP than WR + DOX (83 ± 12 vs. 109 ± 6 mm Hg baseline, 76 ± 11 vs. 100 ± 10 mm Hg recovery, P < 0.05). WR + DOX showed higher dP/dt max and lower dP/dt min when compared with SED + DOX during DOB infusion (7311 ± 1481 vs. 5167 ± 1436 mm Hg/s and -4059 ± 1114 vs.-3158 ± 1176 mm Hg/s, respectively). SED + DOX dP/dt max was significantly lower during baseline and during recovery when compared with all other groups ( P < 0.05). These data suggest that exercise preconditioning preserved cardiac function after DOX exposure even when the heart is challenged with DOB, and it appeared to preserve the heart's ability to recover from this functional challenge.

The Effects of Dobutamine in Septic Shock: An Updated Narrative Review of Clinical and Experimental Studies

The key objective in the hemodynamic treatment of septic shock is the optimization of tissue perfusion and oxygenation. This is usually achieved by the utilization of fluids, vasopressors, and inotropes. Dobutamine is the inotrope most commonly recommended and used for this purpose. Despite the fact that dobutamine was introduced almost half a century ago in the treatment of septic shock, and there is widespread use of the drug, several aspects of its pharmacodynamics remain poorly understood. In normal subjects, dobutamine increases contractility and lacks a direct effect on vascular tone. This results in augmented cardiac output and blood pressure, with reflex reduction in systemic vascular resistance. In septic shock, some experimental and clinical research suggest beneficial effects on systemic and regional perfusion. Nevertheless, other studies found heterogeneous and unpredictable effects with frequent side effects. In this narrative review, we discuss the pharmacodynamic characteristics of dobutamine and its physiologic actions in different settings, with special reference to septic shock. We discuss studies showing that dobutamine frequently induces tachycardia and vasodilation, without positive actions on contractility. Since untoward effects are often found and therapeutic benefits are occasional, its profile of efficacy and safety seems low. Therefore, we recommend that the use of dobutamine in septic shock should be cautious. Before a final decision about its prescription, efficacy, and tolerance should be evaluated throughout a short period with narrow monitoring of its wanted and side effects.

Structure and dynamic simulation-based interactions of benzenoids, pyrroles and organooxygen compounds for effective targeting of GPX4 in ischemic stroke

The discovery of a novel drug for ischemic stroke is plagued by expensive and unsuccessful outcomes. FDA-approved drugs could be a viable repurposing strategy for stroke therapy. Emerging evidence suggests the regulating role of Glutathione peroxidase (GPX4) in stroke and attracts as a potential target. To overcome limited therapeutic interventions, a drug repurposing in silico investigation of FDA-approved drugs is proposed for the GPX4 receptor in distinctive species (Homo sapiens and Mus musculus). The GPX4 UniProt wild type ids, that is, P36969 (Homo sapiens), P36970 (Rattus norvegicus) and O70325 (Mus musculus) are Swiss modelled, and resultant templates are 2OBI and 6HN3 for Homo sapiens, and 5L71 for Mus musculus with a sequence identity of ∼88%. Enrichment analysis reveals high sensitivity and ranked actives with ROC and AUC values of 0.59 and 0.61, respectively. Virtual screening at extra precision resulted hit Acarbosum, is similar between 2OBI and 6HN3, demonstrating a multiple-target specificity and Iopromide, targeting 2OBI. MD simulation at 100 ns following trajectory analysis provides RMSD (∼1.2-1.8Å), RMSF (∼1.6-2.7Å), Rgyr (∼15-15.6Å) depicting stabilisation of receptor-ligand complexes. Furthermore, average B-factor value of 2OBI, 6HN3 and 5L71 is 25Å, 24Å and 60Å with a defined resolution of 1.55Å, 1.01Å and 1.80Å, respectively, depicting the thermodynamic stability of the protein structures. The dynamic cross-correlation and principal component analysis of residual fluctuations reveal more positive correlation, high atomic displacements and greater residual clustering of residues from atomic coordinates. Therefore, Acarbosum, an FDA-approved drug, could act as a potential repurposing drug with a multi-target approach translating from preclinical to clinical stages.Communicated by Ramaswamy H. Sarma.

Comparing the hemodynamic effect of a large arteriovenous fistula during high and low cardiac output states

Background: A large arteriovenous fistula (AVF) is a low-resistant circuit that affects organ perfusion and systemic hemodynamics even in standard conditions. The extent of its' effect in critical states has not been elucidated yet. We used norepinephrine to create systemic vasoconstriction, dobutamine to create high cardiac output, and rapid right ventricle pacing as a model of acute heart failure in a porcine model of high-flow AVF circulation. Methods: The protocol was performed on nine domestic female pigs under general anesthesia. AVF was created by connecting two high-diameter ECMO cannulas inserted in the femoral artery and vein. Continuous hemodynamic monitoring was performed throughout the protocol. Three interventions were performed-moderate dose of norepinephrine (0.25 ug/kg/min), moderate dose of dobutamine (10 ug/kg/min) and rapid right ventricle pacing to simulate low cardiac output state with mean arterial pressure under 60 mmHg. Measurements were taken with opened and closed arteriovenous fistula. Results: Continuous infusion of norepinephrine with opened AVF significantly increased mean arterial pressure (+20%) and total cardiac output (CO) (+36%), but vascular resistance remained virtually unchanged. AVF flow (Qa) rise correlated with mean arterial pressure increase (+20%; R = 0.97, p = 0.0001). Effective cardiac output increased, leading to insignificant improvement in organ perfusion. Dobutamine substantially increased cardiac output with insignificant effect on AVF flow and mean arterial pressure. Carotid artery blood flow increased significantly after dobutamine infusion by approximately 30%, coronary flow velocity increased significantly only in closed AVF state. The effective cardiac output using the heart failure model leading to decrease of carotid artery flow and worsening of brain and peripheral tissue oximetry. AVF blood flow also dropped significantly and proportionally to pressure, but Qa/CO ratio did not change. Therefore, the effective cardiac output decreased. Conclusion: In abovementioned extreme hemodynamic conditions the AVF flow was always directly proportional to systemic perfusion pressure. The ratio of shunt flow to cardiac output depended on systemic vascular resistance. These experiments highlight the detrimental role of a large AVF in these critical conditions' models.

Comparison of metaraminol versus no metaraminol on time to resolution of shock in critically ill patients

OBJECTIVE

There is limited evidence to support metaraminol use in critically ill patients. Metaraminol is not included as a vasopressor choice in international guidelines for the management of shock. Nevertheless, metaraminol is used in rates up to 42% in this patient population. The objective of this study was to investigate the effectiveness of metaraminol for the treatment of critically ill patients with shock.

METHODS

A single-centre retrospective matched observational study was conducted in a 54-bed intensive care unit of a tertiary hospital. Patients aged 16 years or older who were admitted from 2017 to 2019 with shock were included. Patients treated with metaraminol and norepinephrine (MET-NOR) were compared with those treated with norepinephrine without metaraminol (NOR). The primary outcome was the time to resolution of shock defined as the time to cessation of vasopressors. The secondary outcome was vasopressor-free days until 28 days.

RESULTS

There were 286 patients included in this study, including 143 patients in each group. The median time to resolution of shock was 44 hours (IQR 28-66 hours) in the MET-NOR group compared with 27 hours (IQR 14-63 hours) in the NOR group (95% CI of median difference 7 to 19 hours; p<0.01). The Cox regression analysis for the time to resolution of shock showed no significant difference between groups (HR 1.24, 95% CI 0.96 to 1.60; p=0.10). However, the proportional hazards assumption was not met (p<0.01). The median number of vasopressor-free days until 28 days was 26 days (IQR 24-27 days) in the MET-NOR group compared with 27 days (IQR 25-27 days) in the NOR group (95% CI of median difference -0.8 to -0.1 day; p<0.01).

CONCLUSION

In critically ill patients, metaraminol may be associated with a longer time to resolution of shock compared with those who do not receive metaraminol.

Altered spontaneous brain activity during dobutamine challenge in healthy young adults: A resting-state functional magnetic resonance imaging study

Introduction

There is a growing interest in exploring brain-heart interactions. However, few studies have investigated the brain-heart interactions in healthy populations, especially in healthy young adults. The aim of this study was to explore the association between cardiovascular and spontaneous brain activities during dobutamine infusion in healthy young adults.

Methods

Forty-eight right-handed healthy participants (43 males and 5 females, range: 22-34 years) underwent vital signs monitoring, cognitive function assessment and brain MRI scans. Cardiovascular function was evaluated using blood pressure and heart rate, while two resting-state functional magnetic resonance imaging (rs-fMRI) methods-regional homogeneity (ReHo) and amplitude of low-frequency fluctuation (ALFF)-were used together to reflect the local neural activity of the brain. Logistic regression was used to model the association between brain and heart.

Results

Results showed that blood pressure and heart rate significantly increased after dobutamine infusion, and the performance in brain functional activity was the decrease in ReHo in the left gyrus rectus and in ALFF in the left frontal superior orbital. The results of logistic regression showed that the difference of diastolic blood pressure (DBP) had significant positive relationship with the degree of change of ReHo, while the difference of systolic blood pressure (SBP) had significant negative impact on the degree of change in ALFF.

Discussion

These findings suggest that the brain-heart interactions exist in healthy young adults under acute cardiovascular alterations, and more attention should be paid to blood pressure changes in young adults and assessment of frontal lobe function to provide them with more effective health protection management.

The impacts of corrected left ventricular ejection time combined with dobutamine on hepatocellular carcinoma patients

To evaluate the clinical effect of corrected left ventricular ejection time (LVETc) combined with dobutamine on the intraoperative management of patients undergoing hepatectomy for hepatocellular carcinoma. Sixty-eight patients with elective proposed pancreaticoduodenectomy, aged 61-78 years, body mass index 19-26 kg/m², and ASA classification II or III, were divided into two groups (n = 34) using the random number table method: the esophageal ultrasound group (S group) and the esophageal ultrasound combined with dobutamine group (D group). In both groups, an esophageal ultrasound probe was placed after induction of anesthesia, and the left ventricular ejection time (LVET) and stroke volume (SV) were measured via a long-axis section of gastric fundus to guide fluid infusion. Nitroglycerin or a combination of dobutamine and nitroglycerine were pumped intravenously from the beginning of surgery to the completion of hemostasis after partial hepatectomy, in groups S or D, respectively. Central Venous Pressure (CVP), heart rate HR, and mean arterial pressure MAP were recorded at entry (T₀), immediately after induction (T₁), at the beginning of the operation (T₂), during hilar occlusion (T₃), after partial hepatectomy (T₄), and after the operation (T₅). SV and LVETc were recorded between T₁ and T₅. At T₀ and T₅, blood samples from radial artery and central vein were taken to determine the concentration of blood lactic acid, and the oxygen supply index (DO₂I) and oxygen uptake rate (O₂ERe) were calculated by blood gas analysis. The operation time, hilar occlusion time, intraoperative urine volume, intraoperative crystalloid and colloid infusion, intraoperative blood loss and blood transfusion, and the occurrence of cardiac gas emboli during the operation were also recorded. Adverse events of cardiovascular, pulmonary, and renal function during and after operation were registered. Sixty-four patients were included in the final analysis. Compared with group S, group D had lower CVP values at T₂-T₃ and higher SV values at T₂-T₅, reduced intraoperative blood loss, significantly increased intraoperative urine output, a smaller total dose of nitroglycerin use, and lower incidences of intraoperative hypotension and cardiac gas emboli (P < 0.05). Esophageal ultrasound detection of LVETc combined with dobutamine ensures hemodynamic stability in patients undergoing partial hepatectomy while reducing the incidence of intraoperative hypotension and air embolism.

Anesthetized guinea pig as a model for drug testing

Based on the World Health Organization statistics, cardiovascular diseases represent the major cause of death worldwide. Although a wide range of treatment approaches and pharmaceuticals is available, the therapy is often not effective enough and therefore health risks for the patient persist. Thus, it is still essential to test new drug candidates for the treatment of various pathophysiological conditions related to cardiovascular system. In vivo models represent indispensable part of preclinical testing of such substances. Anesthetized guinea pig as a whole-body model allows to evaluate complex reactions of cardiovascular system to tested substance. Moreover, action potential of guinea pig cardiomyocyte is quite comparable to that of human. Hence, the results from this model are then quite well translatable to clinical medicine. Aim of this paper was to summarize the methodology of this model, including its advantages and/or limitations and risks, based on the effects of two substances with adrenergic activity on the ECG parameters. The model of anesthetized guinea pig proved to be valuable and suitable for testing of drugs with cardiovascular effects.

Dos and don'ts in large animal models of aortic insufficiency

Aortic insufficiency caused by paravalvular leakage (PVL) is one of the most feared complications following transcatheter aortic valve replacement (TAVI) in patients. Domestic pigs (Sus scrofa domestica) are a popular large animal model to study such conditions and develop novel diagnostic and therapeutic techniques. However, the models based on prosthetic valve implantation are time intensive, costly, and often hamper further hemodynamic measurements such as PV loop and 4D MRI flow by causing implantation-related wall motion abnormalities and degradation of MR image quality. This study describes in detail, the establishment of a minimally invasive porcine model suitable to study the effects of mild-to-moderate “paravalvular“ aortic regurgitation on left ventricular (LV) performance and blood flow patterns, particularly under the influence of altered afterload, preload, inotropic state, and heart rate. Six domestic pigs (Swiss large white, female, 60–70 kg of body weight) were used to establish this model. The defects on the hinge point of aortic leaflets and annulus were created percutaneously by the pierce-and-dilate technique either in the right coronary cusp (RCC) or in the non-coronary cusp (NCC). The hemodynamic changes as well as LV performance were recorded by PV loop measurements, while blood flow patterns were assessed by 4D MRI. LV performance was additionally challenged by pharmaceutically altering cardiac inotropy, chronotropy, and afterload. The presented work aims to elaborate the dos and don'ts in porcine models of aortic insufficiency and intends to steepen the learning curve for researchers planning to use this or similar models by giving valuable insights ranging from animal selection to vascular access choices, placement of PV Loop catheter, improvement of PV loop data acquisition and post-processing and finally the induction of paravalvular regurgitation of the aortic valve by a standardized and reproducible balloon induced defect in a precisely targeted region of the aortic valve.

The pharmacotherapeutic options in patients with catecholamine-resistant vasodilatory shock

INTRODUCTION

Septic and vasoplegic shock are common types of vasodilatory shock (VS) with high mortality. After fluid resuscitation and the use of catecholamine-mediated vasopressors (CMV), vasopressin, angiotensin II, methylene blue (MB) and hydroxocobalamin can be added to maintain blood pressure.

AREAS COVERED

VS treatment utilizes a phased approach with secondary vasopressors added to vasopressor agents to maintain an acceptable mean arterial pressure (MAP). This review covers additional vasopressors and adjunctive therapies used when fluid and catecholamine-mediated vasopressors fail to maintain target MAP.

EXPERT OPINION

Evidence supporting additional vasopressor agents in catecholamine resistant VS is limited to case reports, series, and a few randomized control trials (RCTs) to guide recommendations. Vasopressin is the most common agent added next when MAPs are not adequately supported with CMV. VS patients failing fluids and vasopressors with cardiomyopathy may have cardiotonic agents such as dobutamine or milrinone added before or after vasopressin. Angiotensin II, another class of vasopressor is used in VS to maintain adequate MAP. MB and/or hydoxocobalamin, vitamin C, thiamine and corticosteroids are adjunctive therapies used in refractory VS. More RCTs are needed to confirm the utility of these drugs, at what doses, which combinations and in what order they should be given.

[Vasoactive drugs in the treatment of septic shock]

Septic shock is a high mortality complication frequently associated with sepsis. Early initiation of vasopressor treatment, even before completion of initial fluid resuscitation, is a determining factor in prognosis. In this sense, norepinephrine continues to be the drug of first choice, although there is increasing evidence of benefit combining it with other non-adrenergic drugs, such as vasopressin, instead of escalating norepinephrine doses. The pathophysiology of septic shock is multifactorial, and sometimes is associated with a situation of myocardial dysfunction that contributes to hemodynamic instability. It is essential to identify this situation since it worsens the prognosis and may benefit from combined treatment with inotropic drugs. There are novel vasoactive agents under study, more selective than the classic ones that in a next future could help to design more individualized and precise treatments. In the present work, the current knowledge about vasoactive drugs and their use in the management of septic shock is summarized according to the most recent scientific evidence.

Inotropes in Patients with Advanced Heart Failure: Not Only Palliative Care

Patients with advanced heart failure suffer from severe and persistent symptoms, often not responding disease-modifying drugs, a marked limitation of functional capacity and poor quality of life that can ameliorate with inotropic drugs therapy. In small studies, pulsed infusions of classical inotropes (ie, dobutamine and milrinone) are associated with improvement in hemodynamic parameters and quality of life in patients with advanced heart failure. However, because of the adverse effects of these drugs, serious safety issues have been raised. Levosimendan is a calcium-sensitizing inodilators with a triple mechanism of action, whose infusion results in hemodynamic, neurohormonal, and inflammatory cytokine improvements in patients with chronic advanced HF. In addition, levosimendan has important pleiotropic effects, including protection of myocardial, renal, and liver cells from ischemia-reperfusion injury, and anti-inflammatory and antioxidant effects; these properties possibly make levosimendan an "organ protective" inodilator. In clinical trials and real-world evidence, infusion of levosimendan at fixed intervals is safe and effective in patients with advanced HF, alleviating clinical symptoms, reducing hospitalizations, and improving the quality of life. Therefore, the use of repeated doses of levosimendan could represent the therapy of choice as a bridge to transplant/left ventricular assist device implantation or as palliative therapy in patients with advanced heart failure.

Baseline left ventricular ejection fraction associated with symptom improvements in both children and adolescents with postural tachycardia syndrome under metoprolol therapy

BACKGROUND

Postural tachycardia syndrome (POTS) is a common childhood disease that seriously affects the patient's physical and mental health. This study aimed to investigate whether pre-treatment baseline left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS) values were associated with symptom improvement after metoprolol therapy for children and adolescents with POTS.

METHODS

This retrospective study evaluated 51 children and adolescents with POTS who received metoprolol therapy at the Peking University First Hospital between November 2010 and July 2019. All patients had completed a standing test or basic head-up tilt test and cardiac echocardiography before treatment. Treatment response was evaluated 3 months after starting metoprolol therapy. The pre-treatment baseline LVEF and LVFS values were evaluated for correlations with decreases in the symptom score after treatment (ΔSS). Multivariable analysis was performed using factors with a P value of <0.100 in the univariate analyses and the demographic characteristics.

RESULTS

A comparison of responders and non-responders revealed no significant differences in demographic, hemodynamic characteristics, and urine specific gravity (all P > 0.050). However, responders had significantly higher baseline LVEF (71.09% ± 4.44% vs. 67.17% ± 4.88%, t = -2.789, P = 0.008) and LVFS values (40.00 [38.00, 42.00]% vs. 36.79% ± 4.11%, Z = -2.542, P = 0.010) than the non-responders. The baseline LVEF and LVFS were positively correlated with ΔSS (r = 0.378, P = 0.006; r = 0.363, P = 0.009), respectively. Logistic regression analysis revealed that LVEF was independently associated with the response to metoprolol therapy in children and adolescents with POTS (odds ratio: 1.201, 95% confidence interval: 1.039-1.387, P = 0.013).

CONCLUSIONS

Pre-treatment baseline LVEF was associated with symptom improvement after metoprolol treatment for children and adolescents with POTS.

Left-Sided Ventricular-arterial Coupling and Volume Responsiveness in Septic Shock Patients

BACKGROUND

Suboptimal ventricular arterial coupling (VAC) is one of the pivotal determinants of inefficient heart performance despite appropriate administration of fluids or vasopressors in shocks. Here, we investigate the performance of VAC in patients who are unresponsive to fluid administration in septic shock.

METHODS

This is a retrospective observational study of septic shock patients (n = 35). VAC was evaluated by effective arterial elastance (EaI), left ventricular end-systolic elastance (EesI), and EaI/EesI. Septic shock patients successfully fluid resuscitated after pulse indicator continuous cardiac output (PiCCO) monitoring, defined as an increase in general end-diastolic ventricular volume (GEDVI) more than 10%, were divided into volume responsive (VVr), and volume unresponsive (VVur) groups based on a cardiac index increase above 10%. We hypothesize that two groups of patients will exhibit dissimilarities of VAC variation, defined as EaI/EesI variation (ΔEaI/EesI).

RESULTS

Variations of EaI (ΔEaI), and EaI/EesI (ΔEaI/EesI), and systemic vascular resistance index (ΔSVRI) were significantly lower in the VVr group than those in the VVur group (P < 0.05). Variations of cardiac index (ΔCI), stroke volume index (ΔSVI), and EesI (ΔEesI) were significantly higher in patients with ΔEaI/EesI ≤ 0. Concomitantly, ΔEaI and ΔSVRI were significantly diminished as compared with patients with ΔEaI/EesI > 0 (P < 0.05). ΔCI has an inverse relationship with both ΔEaI (r = -0.46, P = 0.006), ΔEaI/EesI (r = -0.65, P < 0.001), and ΔSVRI (r = -0.59, P < 0.001). We observed more patients who were fluid responsive in the ΔEaI/EesI ≤ 0 group than in the group with ΔEaI/EesI > 0 (88.89% vs. 26.92%, P = 0.01).

CONCLUSIONS

Variation of VAC is often related to suboptimal ventricular volume responsiveness among patients with septic shock.

The initial resuscitation of septic shock

Septic shock is the most severe form of sepsis, characterized by (a) persistent hypotension despite fluid resuscitation and (b) the presence of tissue hypoperfusion. Delays in the diagnosis and initiation of treatment of septic shock is associated with increasing risk for mortality. Early and effective fluid resuscitation and vasopressor administration play a crucial role in maintaining tissue perfusion in septic shock patients. A low diastolic arterial pressure (DAP) correlates with severity of arteriolar vasodilation, compromises left ventricle oxygen supply and can be used for identifying septic shock patients that would potentially benefit from earlier vasopressor therapy. Controversy currently exists as to the balance of fluids and vasopressors to maintain target mean arterial pressure. The aim of this article is to review the rationale for fluid resuscitation and vasopressor therapy and the importance of both mean and diastolic blood pressure during the initial resuscitation of the septic shock. We relate our personal prescription of balancing fluids and vasopressors in the resuscitation of septic shock.

Designing new generation of potent inhibitors against membrane-type matrix metalloproteinase-2: a computational effort against multiple myeloma

Matrix metalloproteinases (MMPs) play important roles in cancer progression and, despite their inhibitors have failed in the clinical trials, they have always been considered as suitable targets for the treatment of tumor. We have recently shown that membrane type (MT) 2-MMPs, is selectively expressed in multiple myeloma (MM) cells and mediates the metastatic characteristics of these cells. In this study, we designed efficient inhibitors against MT2-MMP using state-of-art molecular modeling methods. First, the 3D structure of MT2-MMP was predicted. Then, the proposed potent inhibitors against two regions of the catalytic domain of MT2-MMP (active site and MT-LOOP) were identified through molecular docking, QM-MM and molecular dynamics simulations from a set of compounds in Analyticon library, IBS library, Maybridge screening fragment library and drugbank library. Moreover, ADME estimation showed that pharmacokinetic properties of inhibitors are in the acceptable range for humans. Finally, our data suggested that compounds 'structures.722' (dobutamine) and 'M2' are suitable candidates to inhibit MT2-MMP for further examination in the laboratory.Communicated by Ramaswamy H. Sarma.

Inotropic and lusitropic effects of incremental doses of dobutamine in dogs with right ventricular apical pacing-induced cardiac dysfunction

This study aimed to assess the effects of incremental doses of dobutamine on diastolic function in healthy and rapid ventricular apical pacing (RVAP)-induced cardiac dysfunction anesthetized dogs. Inotropic and lusitropic effects of dobutamine (2, 4, 8, and 12 μg kg^-1  min^-1 ) were assessed through left ventricle (LV) pressure-volume relation and Doppler echocardiography in six female dogs before and after 8 weeks of RVAP. Peak rate of LV pressure fall (-dP/dt_min ) improved with doses >4 μg kg^-1  min^-1 in healthy (4,490 ± 970 vs. 3,265 ± 471 mmHg/s, p < 0.05) and >8 μg kg^-1  min^-1 in RVAP dogs (3,385 ± 1,122 vs. 1,864 ± 849 mmHg/s, p < 0.05) while the time constant of relaxation (tau) reduced with doses >4 μg kg^-1  min^-1 in both groups (healthy: 24.0 ± 3.7 vs. 28.2 ± 4.9 ms; RVAP: 32.6 ± 8.5 vs. 37.5 ± 11.4 ms, p < 0.05) comparing with baseline. Indices of relaxation (-dP/dt_min and tau) suggested preserved lusitropic response in contrast with markedly reduced indices of contractility in the RVAP group compared with healthy group at same infusion rates. Doppler echocardiography showed significant reduction of elastic recoil in failing hearts. The results of this study demonstrated maximal positive lusitropic effects of dobutamine at a dose of 8 μg kg^-1  min^-1 in ventricular pacing-induced cardiac dysfunction without further impairment of ventricular filling.