Prognosis value of central venous oxygen saturation in acute decompensated heart failure

Oxygen venous saturation is associated with subclinical myocardial systolic dysfunction in patients with end-stage renal disease undergoing hemodialysis

Introduction

The aim of this prospective study was to evaluate the impact of hemodialysis (HD) on myocardial injury, of both right and left ventricle function as well as their association with venous oxygen saturation (ScvO2) alterations.

Material and methods

We included in the study stable consecutive patients with end-stage renal disease (ESRD) undergoing regular HD. Right and left ventricular speckle-tracking echocardiographies were performed in all patients. The examination calculates the global systolic longitudinal strain (GLS). Blood samples were obtained from the central vein in order to measure the O2 saturation (ScvO2) levels prior and post HD. High sensitive troponin (HST) was also measured in all patients before and after HD.

Results

Thirty seven patients were evaluated. We found that both mean ScvO2 and left ventricle GLS (LV GLS) were deteriorated after the dialysis session: 76.47 ±1.98 to 71.54 ±5.10, p < 0.05 and -17.73 ±3.44 to -14.21 ±3.44%, p < 0.01, respectively. HST levels were increased at the end of hemodialysis, 22.45 ±13.26 to 106.78 ±146.19 pg/ml, p < 0.01. A significant correlation was also found between the decrease of LV GLS with the ScvO2 reduction, p = 0.001, as well as with the increase of the HST levels, p = 0.001.

Conclusions

Our data demonstrate that there is a significant worsening of the GLS of the left ventricle at the end of the dialysis, which is strongly associated with the concomitant deterioration of ScvO2. The may be a reliable index of circulatory stress indicating a subclinical myocardial dysfunction during HD.

Cardiogenic Shock: Pathogenesis, Classification, and Management

Cardiogenic shock (CS) is a life-threatening circulatory failure syndrome which can progress rapidly to irreversible multiorgan failure through self-perpetuating pathophysiological processes. Recent developments in CS classification have highlighted its etiologic, mechanistic, and hemodynamic heterogeneity. Optimal CS management depends on early recognition, rapid reversal of the underlying cause, and prompt initiation of hemodynamic support.

QSM Throughout the Body

Magnetic materials in tissue, such as iron, calcium, or collagen, can be studied using quantitative susceptibility mapping (QSM). To date, QSM has been overwhelmingly applied in the brain, but is increasingly utilized outside the brain. QSM relies on the effect of tissue magnetic susceptibility sources on the MR signal phase obtained with gradient echo sequence. However, in the body, the chemical shift of fat present within the region of interest contributes to the MR signal phase as well. Therefore, correcting for the chemical shift effect by means of water-fat separation is essential for body QSM. By employing techniques to compensate for cardiac and respiratory motion artifacts, body QSM has been applied to study liver iron and fibrosis, heart chamber blood and placenta oxygenation, myocardial hemorrhage, atherosclerotic plaque, cartilage, bone, prostate, breast calcification, and kidney stone.

The influence of intra-aortic balloon counter pulsation on central venous blood oxygen saturation

OBJECTIVES

We aim at identifying the changes in venous blood saturation values that associates intra-aortic balloon pump (IABP) in cardiac surgery patients with reduced left ventricular function (LVF).

METHODS

A retrospective observational study was conducted in a cardiothoracic intensive care unit (CTICU) in a tertiary cardiac center over 5 years in Qatar. A total of 114 patients with at least moderate impairment of LVF with ejection fraction (EF) less than 40% were enrolled. According to the association of IABP, patients were segregated into two groups with and without IABP (groups 1, 40 patients and group 2, 74 patients). Sequential arterial and venous blood gases were analyzed. The primary outcome was to analyze the changes in the central venous saturation (ScvO₂) in both groups and the secondary outcome was to analyze whether these changes affect the overall outcome in terms of intensive care unit (ICU) length of stay.

RESULTS

There was no significant difference between both groups with regard to age, preoperative EF, hemoglobin, and arterial oxygen saturation (SaO₂) in blood gases. Patients with IABP have a higher cScvO₂ when compared to the other group (71.5 ± 12.5 vs 63.5 ± 9.3, 68.3 ± 12.6 vs 60.1 ± 9.5, 62.7 ± 10.8 vs 55.63 ± 8.1, and 60.6 ± 7.6 vs 54.9 ± 8.1; p = 0.04, 0.05, 0.03, and 0.5, respectively). However, generalized estimating equations (GEE) analysis showed that compared with the participants showing that there is a decreasing trend in mean levels within the groups during follow-ups, overall difference between both groups' mean levels was not statistically significant.

CONCLUSIONS

In this study, we observed that after cardiac surgeries, patients with IABP had non-significant higher ScvO₂ when compared with a corresponding group with moderate impairment of LVF. Further prospective studies are required to validate these findings.

Quantitative susceptibility mapping (QSM) of the cardiovascular system: challenges and perspectives

Quantitative susceptibility mapping (QSM) is a powerful, non-invasive, magnetic resonance imaging (MRI) technique that relies on measurement of magnetic susceptibility. So far, QSM has been employed mostly to study neurological disorders characterized by iron accumulation, such as Parkinson's and Alzheimer's diseases. Nonetheless, QSM allows mapping key indicators of cardiac disease such as blood oxygenation and myocardial iron content. For this reason, the application of QSM offers an unprecedented opportunity to gain a better understanding of the pathophysiological changes associated with cardiovascular disease and to monitor their evolution and response to treatment. Recent studies on cardiovascular QSM have shown the feasibility of a non-invasive assessment of blood oxygenation, myocardial iron content and myocardial fibre orientation, as well as carotid plaque composition. Significant technical challenges remain, the most evident of which are related to cardiac and respiratory motion, blood flow, chemical shift effects and susceptibility artefacts. Significant work is ongoing to overcome these challenges and integrate the QSM technique into clinical practice in the cardiovascular field.

Optimal Perfusion Targets in Cardiogenic Shock

Cardiology shock is a syndrome of low cardiac output resulting in end-organ dysfunction. Few interventions have demonstrated meaningful clinical benefit, and cardiogenic shock continues to carry significant morbidity with mortality rates that have plateaued at upwards of 40% over the past decade. Clinicians must rely on clinical, biochemical, and hemodynamic parameters to guide resuscitation. Several features, including physical examination, renal function, serum lactate metabolism, venous oxygen saturation, and hemodynamic markers of right ventricular function, may be useful both as prognostic markers and to guide therapy. This article aims to review these targets, their utility in the care of patients with cardiology shock, and their association with outcomes.

Complete percutaneous angio-guided approach using preclosing for venoarterial extracorporeal membrane oxygenation implantation and explantation in patients with refractory cardiogenic shock or cardiac arrest

BACKGROUND

The approach for veno-arterial extracorporeal membrane oxygenation implantation (VA-ECMO) in patients with cardiogenic shock can be either surgical or percutaneous. Complete angio-guided percutaneous implantation and explantation could decrease vascular complications. We sought to describe the initial results of complete percutaneous angio-guided ECMO implantation and explantation using preclosing.

METHODS

All consecutive patients who underwent peripheral femoro-femoral VA-ECMO percutaneous implantation for refractory cardiogenic shock or cardiac arrest were enrolled in a prospective registry (03/2018-12/2020). Percutaneous preclosing using two closing devices (Perclose ProGlide, Abbott) inserted before cannulation was used in both femoral artery and vein. Explantation was performed using a crossover technique under angiographic guidance. The occurrence of vascular complication was recorded.

RESULTS

Among the 56 patients who underwent percutaneous VA-ECMO implantation for cardiogenic shock or refractory cardiac arrest, 41 underwent preclosing. Femoral vessel cannulation was successful in all patients and total cannulation time was 20 (10-40) min. Weaning from ECMO was possible in 22/41 patients (54%) and 12 (29%) patients were alive at day 30. Significant vascular complications occurred in 2/41 patients. Percutaneous decannulation was performed in 20 patients with 19/20 technical success rate. All femoral arteries and veins were properly closed using the pre-closing devices without bleeding on the angiographic control except for one patient in whom surgical closure of the artery was required. No patient required transfusion for access related significant bleeding and no other vascular complication occurred. Furthermore, no groin infection was observed after full percutaneous implantation and removal of ECMO.

CONCLUSION

Emergent complete percutaneous angio-guided VA-ECMO implantation and explantation using pre-closing technique can be an attractive strategy in patients referred for refractory cardiogenic shock.

Levosimendan Plus Dobutamine in Acute Decompensated Heart Failure Refractory to Dobutamine

Randomized studies showed that Dobutamine and Levosimendan have similar impact on outcome but their combination has never been assessed in acute decompensated heart failure (ADHF) with low cardiac output. This is a retrospective, single-center study that included 89 patients (61 ± 15 years) admitted for ADHF requiring inotropic support. The first group consisted of patients treated with dobutamine alone (n = 42). In the second group, levosimendan was administered on top of dobutamine, when the superior vena cava oxygen saturation (ScVO2) remained <60% after 3 days of dobutamine treatment (n = 47). The primary outcome was the occurrence of major cardiovascular events (MACE) at 6 months, defined as all cause death, heart transplantation or need for mechanical circulatory support. Baseline clinical characteristics were similar in both groups. At day-3, the ScVO2 target (>60%) was reached in 36% and 32% of patients in the dobutamine and dobutamine-levosimendan group, respectively. After adding levosimendan, 72% of the dobutamine-levosimendan-group reached the ScVO2 target value at dobutamine weaning. At six months, 42 (47%) patients experienced MACE (n = 29 for death). MACE was less frequent in the dobutamine-levosimendan (32%) than in the dobutamine-group (64%, p = 0.003). Independent variables associated with outcome were admission systolic blood pressure and dobutamine-levosimendan strategy (OR = 0.44 (0.23–0.84), p = 0.01). In conclusion, levosimendan added to dobutamine may improve the outcome of ADHF refractory to dobutamine alone.

Sepsis With Preexisting Heart Failure: Management of Confounding Clinical Features

Preexisting heart failure (HF) in patients with sepsis is associated with worse clinical outcomes. Core sepsis management includes aggressive volume resuscitation followed by vasopressors (and potentially inotropes) if fluid is inadequate to restore perfusion; however, large fluid boluses and vasoactive agents are concerning amid the cardiac dysfunction of HF. This review summarizes evidence regarding the influence of HF on sepsis clinical outcomes, pathophysiologic concerns, resuscitation targets, hemodynamic interventions, and adjunct management (ie, antiarrhythmics, positive pressure ventilatory support, and renal replacement therapy) in patients with sepsis and preexisting HF. Patients with sepsis and preexisting HF receive less fluid during resuscitation; however, evidence suggests traditional fluid resuscitation targets do not increase the risk of adverse events in HF patients with sepsis and likely improve outcomes. Norepinephrine remains the most well-supported vasopressor for patients with sepsis with preexisting HF, while dopamine may induce more cardiac adverse events. Dobutamine should be used cautiously given its generally detrimental effects but may have an application when combined with norepinephrine in patients with low cardiac output. Management of chronic HF medications warrants careful consideration for continuation or discontinuation upon development of sepsis, and β-blockers may be appropriate to continue in the absence of acute hemodynamic decompensation. Optimal management of atrial fibrillation may include β-blockers after acute hemodynamic stabilization as they have also shown independent benefits in sepsis. Positive pressure ventilatory support and renal replacement must be carefully monitored for effects on cardiac function when HF is present.

Hemodynamic monitoring in patients with venoarterial extracorporeal membrane oxygenation

Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is an effective mechanical circulatory support modality that rapidly restores systemic perfusion for circulatory failure in patients. Given the huge increase in VA-ECMO use, its optimal management depends on continuous and discrete hemodynamic monitoring. This article provides an overview of VA-ECMO pathophysiology, and the current state of the art in hemodynamic monitoring in patients with VA-ECMO.

Free breathing three-dimensional cardiac quantitative susceptibility mapping for differential cardiac chamber blood oxygenation - initial validation in patients with cardiovascular disease inclusive of direct comparison to invasive catheterization

BACKGROUND

Differential blood oxygenation between left (LV) and right ventricles (RV; ΔSaO2) is a key index of cardiac performance; LV dysfunction yields increased RV blood pool deoxygenation. Deoxyhemoglobin increases blood magnetic susceptibility, which can be measured using an emerging cardiovascular magnetic resonance (CMR) technique, Quantitative Susceptibility Mapping (QSM) - a concept previously demonstrated in healthy subjects using a breath-hold 2D imaging approach (2DBHQSM). This study tested utility of a novel 3D free-breathing QSM approach (3DNAVQSM) in normative controls, and validated 3DNAVQSM for non-invasive ΔSaO2 quantification in patients undergoing invasive cardiac catheterization (cath).

METHODS

Initial control (n = 10) testing compared 2DBHQSM (ECG-triggered 2D gradient echo acquired at end-expiration) and 3DNAVQSM (ECG-triggered navigator gated gradient echo acquired in free breathing using a phase-ordered automatic window selection algorithm to partition data based on diaphragm position). Clinical testing was subsequently performed in patients being considered for cath, including 3DNAVQSM comparison to cine-CMR quantified LV function (n = 39), and invasive-cath quantified ΔSaO2 (n = 15). QSM was acquired using 3 T scanners; analysis was blinded to comparator tests (cine-CMR, cath).

RESULTS

3DNAVQSM generated interpretable QSM in all controls; 2DBHQSM was successful in 6/10. Among controls in whom both pulse sequences were successful, RV/LV susceptibility difference (and ΔSaO2) were not significantly different between 3DNAVQSM and 2DBHQSM (252 ± 39 ppb [17.5 ± 3.1%] vs. 211 ± 29 ppb [14.7 ± 2.0%]; p = 0.39). Acquisition times were 30% lower with 3DNAVQSM (4.7 ± 0.9 vs. 6.7 ± 0.5 min, p = 0.002), paralleling a trend towards lower LV mis-registration on 3DNAVQSM (p = 0.14). Among cardiac patients (63 ± 10y, 56% CAD) 3DNAVQSM was successful in 87% (34/39) and yielded higher ΔSaO2 (24.9 ± 6.1%) than in controls (p < 0.001). QSM-calculated ΔSaO2 was higher among patients with LV dysfunction as measured on cine-CMR based on left ventricular ejection fraction (29.4 ± 5.9% vs. 20.9 ± 5.7%, p < 0.001) or stroke volume (27.9 ± 7.5% vs. 22.4 ± 5.5%, p = 0.013). Cath measurements (n = 15) obtained within a mean interval of 4 ± 3 days from CMR demonstrated 3DNAVQSM to yield high correlation (r = 0.87, p < 0.001), small bias (- 0.1%), and good limits of agreement (±8.6%) with invasively measured ΔSaO2.

CONCLUSION

3DNAVQSM provides a novel means of assessing cardiac performance. Differential susceptibility between the LV and RV is increased in patients with cine-CMR evidence of LV systolic dysfunction; QSM-quantified ΔSaO2 yields high correlation and good agreement with the reference of invasively-quantified ΔSaO2.

Serum lactate poorly predicts central venous oxygen saturation in critically ill patients: a retrospective cohort study

Background

Serum lactate and central venous oxygen saturation (ScvO₂) are commonly used and commonly recommended as markers of tissue oxygenation in shock states. Medical literature has both explicitly stated and implied that the two biomarkers are interchangeable in the management of patients with shock. However, there have been relatively few direct comparisons of these tests in clinical circumstances, and the relationship between them is uncertain. The objective of our study was to evaluate whether simultaneous or near-simultaneous measurements of lactate and ScvO₂ reveal a consistent relationship between these two biomarkers.

Methods

A retrospective cohort study was conducted in an urban, academic US hospital. All adults in ICUs between March 2007 and March 2017 who had a lactate measurement and ScvO₂ or mixed venous oxygen saturation (SvO₂) measurement made +/− 1 h from the lactate were included. Linear and non-linear correlations of ScvO₂ and lactate were assessed in a variety of shock states.

Results

Two thousand sixty-two patients were included. Lactate and ScvO₂ correlated poorly (r² = 0.0041, p = 0.0019). This was true for patients with ScvO₂ ≤ 65% (r² = 0.0431, p < 0.001), patients with normal kidney and liver function (r² = 0.0517, p < 0.001), and septic shock patients (r² = 0.0037, p = 0.17). For patients with an O₂ extraction ratio ≥ 50%, lactate and ScvO₂ were strongly correlated (r² = 0.93, p = 0.0019), but these patients represented only 2.8% of patients in whom the ratio could be calculated.

Conclusions

Lactate can predict ScvO₂ when patients are at or below the critical oxygen delivery threshold, but relatively few shock patients meet this criterion. In the overall population of critically ill patients, serum lactate predicts ScvO₂ poorly, even after controlling for factors that may affect lactate production. Lactate and ScvO₂ should not be assumed to be interchangeable markers of tissue oxygenation/perfusion.

Electronic supplementary material

The online version of this article (10.1186/s40560-019-0401-5) contains supplementary material, which is available to authorized users.

Controlled decongestion by Reprieve therapy in acute heart failure: results of the TARGET-1 and TARGET-2 studies

AIMS

Safe and effective decongestion is the main goal of therapy in acute heart failure (AHF). In the non-randomized, prospective TARGET-1 and TARGET-2 studies (NCT03897842), we investigated whether adding the Reprieve System® (which continuously monitors urine output and delivers a matched volume of hydration fluid sufficient to maintain the set fluid balance rate) to standard diuretic-based regimen improves decongestion in AHF.

METHODS AND RESULTS

The population consisted of 19 patients hospitalized with AHF (mean age 67 ± 10 years, 18 male, ejection fraction 34 ± 15%, median N-terminal pro-B-type natriuretic peptide 4492 pg/mL). Patients served as their own controls: each patient underwent 24 h of standard diuretic therapy followed by 24 h of diuretics with Reprieve therapy (with normal saline used for matched volume replacement). The primary efficacy endpoint of actual fluid loss not exceeding the target fluid loss at the end of therapy was met in all 19 (100%) patients. The mean diuresis during Reprieve therapy was 6284 ± 2679 mL (vs. 1966 ± 1057 mL 24 h before therapy) and 2053 ± 888 mL (24 h after therapy) (both P < 0.0001). At the end of therapy, patient global assessment improved from 7.7 ± 1.1 to 3.0 ± 1.3 points (P < 0.001), central venous pressure decreased from 15.5 ± 5.3 mmHg to 12.8 ± 4.8 mmHg (P < 0.05) and the median urine sodium loss was 9.7 [3-13] mmol/h. The Reprieve therapy was safe, systolic blood pressure remained stable, mean creatinine dropped from 1.45 ± 0.4 mg/dL to 1.26 ± 0.4 mg/dL (P < 0.001) and biomarkers of renal injury did not change during treatment.

CONCLUSIONS

The Reprieve System in conjunction with diuretic therapy supports safe and controlled decongestion in AHF.

Beyond Mean Arterial Pressure and Lactate: Perfusion End Points for Managing the Shocked Patient

Patients in shock present frequently to the emergency department. The emergency physician must be skilled in the resuscitation of both differentiated and undifferentiated shock. Early, aggressive resuscitation of patients in shock is essential, using macrocirculatory, microcirculatory, and clinical end points to guide interventions. Therapy should focus on the restoration of oxygen delivery to match tissue demand. This article reviews the evidence supporting common end points of resuscitation for common etiologies of shock and limitations to their use.

Venous oxygen saturation in critical illness

OBJECTIVE

To review clinically relevant features of systemic oxygen delivery and consumption and the technique and use of venous oxygenation monitoring in human and veterinary medicine.

DATA SOURCES

Veterinary and human peer-reviewed medical literature including scientific reviews, clinical and laboratory research articles, and authors' clinical research experience.

SUMMARY

Measurement of venous hemoglobin oxygen saturation (venous oxygenation) provides insight into the balance between oxygen supply and tissue demand. In people, measurement of venous oxygen saturation can reveal decompensation that is missed by physical examination and other routinely monitored parameters. Therefore, measurement of mixed or central venous oxygenation measurement may help guide therapy and predict outcome of critically ill patients. In dogs, low central venous oxygen saturation has been associated with impaired cardiopulmonary function and poor outcome in several small studies of experimental shock or severe clinical illness, suggesting that monitoring this variable may assist the treatment of severe illness in this species as well.

CONCLUSION

Venous oxygenation reflects systemic oxygenation status and can be used to guide treatment and estimate prognosis in critically ill patients. Measurement of venous oxygenation in veterinary patients is feasible and is a potentially valuable tool in the management of patients with severe disease. This review is intended to increase the understanding and awareness of the potential role of venous oxygen measurement in veterinary patients.

Monitoring of Tissue Oxygenation: an Everyday Clinical Challenge

Purpose of review

The aim of this article is to study the overview of pathophysiology and clinical application of central venous oxygen saturation monitoring in critically ill patients and during the perioperative period.

Recent findings

There are several clinical studies and animal experiments evaluating the effects of goal-directed hemodynamic stabilization on critically ill patients. Recent systematic reviews and meta-analyses found that advanced hemodynamic endpoints-targeted management has a positive effect on outcome in high-risk surgical patients. As all interventions aim to improve tissue oxygenation, it is of utmost importance to monitor the balance between oxygen delivery and consumption. For this purpose, central venous blood gas analysis provides an easily available tool in the everyday clinical practice. The adequate interpretation of central venous oxygen saturation renders the need of careful evaluation of several physiological and pathophysiological circumstances. When appropriately evaluated, central venous oxygen saturation can be a valuable component of a multimodal individualized approach, in which components of oxygen delivery are put in the context of the patients' individual oxygen consumption. In addition to guide therapy, central venous oxygen saturation may also serve as an early warning sign of inadequate oxygen delivery, which would otherwise remain hidden from the attending physician.

Summary

With the incorporation of central venous oxygen saturation in the everyday clinical routine, treatment could be better tailored for the patients' actual needs; hence, it may also improve outcome.

Systematic review of the association of venous oxygenation and outcome in adult hospitalized patients

BACKGROUND

Adequate tissue oxygenation is necessary to maintain organ function. Low venous oxygen saturation may reflect impaired tissue oxygenation, and may be used as a predictive tool and a therapeutic target to improve the care of critically ill patients. We therefore conducted a systematic review of the existing literature reflecting these aspects.

METHODS

We searched electronic databases in January 2016 for relevant studies on venous oxygen saturation for treatment guidance and patient outcome. We sub-grouped results based on patient groups and setting.

RESULTS

The search resulted in 5590 papers of which 42 studies were deemed relevant. The majority of the studies in cardiac and abdominal surgery patients showed associations between low venous oxygen saturation and increased mortality and morbidity, in particular increased length of intensive care. However, the cut-off level for low venous oxygen saturation varied between < 55 and 70% and all studies had high risk of bias. In patients with septic shock, recent randomized trials showed no benefit of early resuscitation guided by venous oxygen saturation.

CONCLUSION

Low venous oxygen saturation may be associated with increased mortality, morbidity and length of intensive care in patients following cardiac or abdominal surgery. However, the wide range of cut-off levels and low quality of evidence hampers the clinical application. In patients with septic shock, the present evidence does not support goal-directed therapy using venous oxygen saturation during early resuscitation.

Online Hemoglobin and Oxygen Saturation Sensing During Continuous Renal Replacement Therapy with Regional Citrate Anticoagulation

Optical hemoglobin and oxygen saturation sensor (OHOS) monitor when used in combination with other hemodynamic tools may be useful for continuous hemodynamic monitoring during ultrafiltration. The stand-alone OHOS monitor can easily be deployed predialyzer into the extracorporeal circuit of continuous renal replacement therapy (CRRT) systems. To maximize the accuracy of the OHOS in 24 hr CRRT systems, clotting in the optical blood chamber and the presensor dilution incurred by replacement fluid should be minimized. Sustained low-efficiency dialysis (SLED) with regional citrate anticoagulation is a therapy that incorporates an OHOS and maintains the overall reliability of hemoglobin (Hb) and saturation sensing. The system operates at a blood flow rate of 60 ml/min and a fixed acid citrate infusion rate of 150 ml/hr. The presensor dilution incurred by concentrated citrate infusion would result in a minimal Hb dilution (<0.7 g/dl) while minimizing optical blood chamber clotting during 24 hr SLED.

Association of left ventricular longitudinal strain with central venous oxygen saturation and serum lactate in patients with early severe sepsis and septic shock

INTRODUCTION

In septic shock, assessment of cardiac function often relies on invasive central venous oxygen saturation (ScvO2). Ventricular strain is a non-invasive method of assessing ventricular wall deformation and may be a sensitive marker of heart function. We hypothesized that it may have a relationship with ScvO2 and lactate.

METHODS

We prospectively performed transthoracic echocardiography in patients with severe sepsis or septic shock and measured (1) left ventricular longitudinal strain from a four-chamber view and (2) ScvO2. We excluded patients for whom image quality was inadequate or for whom ScvO2 values were unobtainable. We determined the association between strain and ScvO2 with logistic and linear regression, using covariates of mean arterial pressure, central venous pressure, and vasopressor dose. We determined the association between strain and lactate. We considered strain greater than -17% as abnormal and strain greater than -10% as severely abnormal.

RESULTS

We studied 89 patients, 68 of whom had interpretable images. Of these patients, 42 had measurable ScvO2. Sixty percent of patients had abnormal strain, and 16% had severely abnormal strain. Strain is associated with low ScvO2 (linear coefficient -1.05, p =0.006; odds ratio 1.23 for ScvO2 <60%, p =0.016). Patients with severely abnormal strain had significantly lower ScvO2 (56.1% vs. 67.5%, p <0.01) and higher lactate (2.7 vs. 1.9 mmol/dl, p =0.04) than those who did not. Strain was significantly different between patients, based on a threshold ScvO2 of 60% (-13.7% vs. -17.2%, p =0.01) but not at 70% (-15.0% vs. -18.2%, p =0.08).

CONCLUSIONS

Left ventricular strain is associated with low ScvO2 and hyperlactatemia. It may be a non-invasive surrogate for adequacy of oxygen delivery during early severe sepsis or septic shock.

Prevalence of low central venous oxygen saturation in the first hours of intensive care unit admission and associated mortality in septic shock patients: a prospective multicentre study

Introduction

In septic shock patients, the prevalence of low (<70%) central venous oxygen saturation (ScvO2) on admission to the intensive care unit (ICU) and its relationship to outcome are unknown. The objectives of the present study were to estimate the prevalence of low ScvO2 in the first hours of ICU admission and to assess its potential association with mortality in patients with severe sepsis or septic shock.

Methods

This was a prospective, multicentre, observational study conducted over a one-year period in ten French ICUs. Clinicians were asked to include patients with severe sepsis or septic shock preferably within 6 hours of ICU admission and as soon as possible without changing routine practice. ScvO2 was measured at inclusion and 6 hours later (H6), by blood sampling.

Results

We included 363 patients. Initial ScvO2 below 70% was present in 111 patients and the pooled estimate for its prevalence was 27% (95% Confidence interval (95%CI): 18% to 37%). At time of inclusion, among 166 patients with normal lactate concentration (≤2 mmol/L), 55 (33%) had a low initial ScvO2 (<70%), and among 136 patients who had already reached the classic clinical endpoints for mean arterial pressure (≥65 mmHg), central venous pressure (≥8 mmHg), and urine output (≥0.5 mL/Kg of body weight), 43 (32%) had a low initial ScvO2 (<70%). Among them, 49% had lactate below 2 mmol/L. The day-28 mortality was higher in case of low initial ScvO2 (37.8% versus 27.4%; P = 0.049). When adjusted for confounders including the Simplified Acute Physiology Score and initial lactate concentration, a low initial ScvO2 (Odds ratio (OR) = 3.60, 95%CI: 1.76 to 7.36; P = 0.0004) and a low ScvO2 at H6 (OR = 2.18, 95%CI: 1.12 to 4.26; P = 0.022) were associated with day-28 mortality by logistic regression.

Conclusions

Low ScvO2 was common in the first hours of admission to the ICU for severe sepsis or septic shock even when clinical resuscitation endpoints were achieved and even when arterial lactate was normal. A ScvO2 below 70% in the first hours of ICU admission and six hours later was associated with day-28 mortality.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-014-0609-7) contains supplementary material, which is available to authorized users.

Hemodynamic effects of Ivabradine in addition to dobutamine in patients with severe systolic dysfunction

BACKGROUND

Dobutamine induced tachycardia increases myocardial oxygen consumption and impairs ventricular filling. We hypothesized that Ivabradine may be efficient to control dobutamine induced tachycardia.

METHODS

We assessed the effects of Ivabradine in addition to dobutamine in stable heart failure (HF) patients (LVEF < 35%, n = 22, test population) and validated its effects in refractory cardiogenic shock patients (n = 9, validation population) with contraindication to cardiac assistance or transplant. In the test population (62 ± 17 years, LVEF = 24 ± 8%), systolic and diastolic function were assessed at rest and under dobutamine [10 γ/min], before and after Ivabradine [5mg per os]. In the validation population (54 ± 11 years, LVEF = 22 ± 7%), Ivabradine [5mg twice a day] was added to the dobutamine infusion.

RESULTS

In the test population, Ivabradine decreased heart rate [HR] at rest and during dobutamine echocardiography (-9 ± 8 bpm, P = 0.0004). The decrease in HR was associated with a decrease in cardiac power output and an increase in diastolic duration at rest (+ 74 ± 67 ms, P = 0.0002), and during dobutamine infusion (+ 75 ± 67 ms, P < 0.0001). Change in LVEF during dobutamine was greater after Ivabradine treatment than before (+ 7.2 ± 4.7% vs. + 3.6 ± 4.2%, P = 0.002). In the validation population, Ivabradine decreased HR (-18 ± 11 bpm, P = 0.008) and improved diastolic filling time (+ 67 ± 42 ms, P = 0.012) without decreasing cardiac output. At 24h, Ivabradine improved systolic blood pressure (+ 9 ± 5 mmHg, P = 0.007), daily urine output (+ 0.7 ± 0.5L, P = 0.008), oxygen balance (ΔScv02 = + 13 ± 15%, P = 0.010), and NT-pro BNP (-2270 ± 1912 pg/mL, P = 0.017). Finally, only 2/9 (22%) patients died whereas expected mortality determined from a historical cohort was 78% (P = 0.017).

CONCLUSION

This pilot study demonstrates the safety and potential benefit of a HR lowering agent in cardiogenic shock.

Blood content analysis for evaluating cardiopulmonary function

PURPOSE OF REVIEW

To review the role of blood analysis in cardiac and pulmonary evaluation.

RECENT FINDINGS

A comprehensive understanding of arterial blood gas analysis - often aided by venous blood gas analysis, to help determine the ideal levels of blood oxygenation and hemoglobin (Hb), is reviewed in light of the recent findings. Serum lactate plays an important role in assessing cardiopulmonary function; yet, with the exception of prognosis, as to exactly what an elevated lactate implies remains unclear. Despite considerable research into the pulmonary-specific biomarkers, none are currently sufficiently robust to use in daily practice. Of the cardiac biomarkers, the natriuretic peptides are yet to be established in critical care practice apart from a role in assisting weaning from a ventilator, and cardiac troponin (cTn) continues to be an essential tool.

SUMMARY

The ongoing research on blood contents has not resulted in any new outstanding markers to the critical care physician to use in evaluating cardiopulmonary function, with the exception of high-sensitive cTn. Yet, many recent studies assist the clinician by providing a better understanding of how to use routine tools, like arterial and venous blood gas analysis, more effectively and offer guidance in optimizing Hb and lactate blood levels.