Cardiovascular effects of lactate in healthy adults

Critical Care volume 29, Article number: 30 (2025) 

Published: 17 January 2025

Background

Low-volume hypertonic solutions, such as half-molar lactate (LAC), may be a potential treatment used for fluid resuscitation. This study aimed to evaluate the underlying cardiovascular effects and mechanisms of LAC infusion compared to sodium-matched hypertonic sodium chloride (SAL).

Methods

Eight healthy male participants were randomized in a controlled, single-blinded, crossover study. Each participant received a four-hour infusion of LAC and SAL in a randomized order. Assessor-blinded echocardiography and blood samples were performed. The primary endpoint was cardiac output (CO) measured by echocardiography.

Results

During LAC infusion, circulating lactate levels increased by 1.9 mmol/L (95% CI 1.8–2.0 mmol/L, P < 0.001) compared with SAL. CO increased by 1.0 L/min (95% CI 0.5–1.4 L/min, P < 0.001), driven primarily by a significant increase in stroke volume of 11 mL (95% CI 4–17 mL, P = 0.002), with no significant change in heart rate. Additionally, left ventricular ejection fraction improved by 5 percentage points (P < 0.001) and global longitudinal strain by 1.5 percentage points (P < 0.001). Preload indicators were elevated during SAL infusion compared with LAC infusion. Concomitantly, afterload parameters, including systemic vascular resistance and effective arterial elastance, were significantly decreased with LAC infusion compared with SAL, while mean arterial pressure remained similar. Indicators of contractility improved during LAC infusion.

Conclusions

In healthy participants, LAC infusion enhanced cardiac function, evidenced by increases in CO, stroke volume, and left ventricular ejection fraction compared with SAL. Indicators of contractility improved, afterload decreased, and preload remained stable. Therefore, LAC infusion may be an advantageous resuscitation fluid, particularly in patients with cardiac dysfunction.

 

Assessment of fluid responsiveness using pulse pressure variation, stroke volume variation, plethysmographic variability index, central venous pressure, and inferior vena cava variation in patients undergoing mechanical ventilation: a systematic review and meta-analysis

Critical Care volume 28, Article number: 289 (2024) Published: 31 August 2024

Importance

Maneuvers assessing fluid responsiveness before an intravascular volume expansion may limit useless fluid administration, which in turn may improve outcomes.

Objective

To describe maneuvers for assessing fluid responsiveness in mechanically ventilated patients.

Registration

The protocol was registered at PROSPERO: CRD42019146781.

Information sources and search

PubMed, EMBASE, CINAHL, SCOPUS, and Web of Science were search from inception to 08/08/2023.

Study selection and data collection

Prospective and intervention studies were selected.

Statistical analysis

Data for each maneuver were reported individually and data from the five most employed maneuvers were aggregated. A traditional and a Bayesian meta-analysis approach were performed.

Results

A total of 69 studies, encompassing 3185 fluid challenges and 2711 patients were analyzed. The prevalence of fluid responsiveness was 49.9%. Pulse pressure variation (PPV) was studied in 40 studies, mean threshold with 95% confidence intervals (95% CI) = 11.5 (10.5–12.4)%, and area under the receiver operating characteristics curve (AUC) with 95% CI was 0.87 (0.84–0.90). Stroke volume variation (SVV) was studied in 24 studies, mean threshold with 95% CI = 12.1 (10.9–13.3)%, and AUC with 95% CI was 0.87 (0.84–0.91). The plethysmographic variability index (PVI) was studied in 17 studies, mean threshold = 13.8 (12.3–15.3)%, and AUC was 0.88 (0.82–0.94). Central venous pressure (CVP) was studied in 12 studies, mean threshold with 95% CI = 9.0 (7.7–10.1) mmHg, and AUC with 95% CI was 0.77 (0.69–0.87). Inferior vena cava variation (∆IVC) was studied in 8 studies, mean threshold = 15.4 (13.3–17.6)%, and AUC with 95% CI was 0.83 (0.78–0.89).

Conclusions

Fluid responsiveness can be reliably assessed in adult patients under mechanical ventilation. Among the five maneuvers compared in predicting fluid responsiveness, PPV, SVV, and PVI were superior to CVP and ∆IVC. However, there is no data supporting any of the above mentioned as being the best maneuver. Additionally, other well-established tests, such as the passive leg raising test, end-expiratory occlusion test, and tidal volume challenge, are also reliable.

A decade of progress in critical care echocardiography: a narrative review

A decade of progress in critical care echocardiography: a narrative review

By: Vieillard-Baron, A., Millington, S.J., Sanfillipo, F. et al.

Intensive Care Med (04/2019). P1-19 – first online: 25^th March 2019

Introduction

This narrative review focusing on critical care echocardiography (CCE) has been written by a group of experts in the field, with the aim of outlining the state of the art in CCE in the 10 years after its official recognition and definition.

Results

In the last 10 years, CCE has become an essential branch of critical care ultrasonography and has gained general acceptance. Its use, both as a diagnostic tool and for hemodynamic monitoring, has increased markedly, influencing contemporary cardiorespiratory management. Recent studies suggest that the use of CCE may have a positive impact on outcomes. CCE may be used in critically ill patients in many different clinical situations, both in their early evaluation of in the emergency department and during intensive care unit (ICU) admission and stay. CCE has also proven its utility in perioperative settings, as well as in the management of mechanical circulatory support. CCE may be performed with very simple diagnostic objectives. This application, referred to as basic CCE, does not require a high level of training. Advanced CCE, on the other hand, uses ultrasonography for full evaluation of cardiac function and hemodynamics, and requires extensive training, with formal certification now available. Indeed, recent years have seen the creation of worldwide certification in advanced CCE. While transthoracic CCE remains the most commonly used method, the transesophageal route has gained importance, particularly for intubated and ventilated patients.

Conclusion

CCE is now widely accepted by the critical care community as a valuable tool in the ICU and emergency department, and in perioperative settings.

Reassessment of the Accuracy of Cardiac Doppler Pulmonary Artery Pressure Measurements in Ventilated ICU Patients: A Simultaneous Doppler-Catheterization Study*

Reassessment of the Accuracy of Cardiac Doppler Pulmonary Artery Pressure Measurements in Ventilated ICU Patients: A Simultaneous Doppler-Catheterization Study*

by Mercado, Pablo; Maizel, Julien; Beyls, Christophe; Kontar, Loay; Orde, Sam; Huang, Stephen; McLean, Anthony; Tribouilloy, Christophe; Slama, Michel  

Critical Care Medicine: January 2019 - Volume 47 - Issue 1 - p 41–48

Objectives: Doppler echocardiography is a well-recognized technique for the noninvasive evaluation of pulmonary artery pressure; however, little information is available concerning patients receiving mechanical ventilation. Furthermore, recent studies have debatable results regarding the relevance of this technique to assess pulmonary artery pressure. The aim of our study was to reassess the accuracy of Doppler echocardiography to evaluate pulmonary artery pressure and to predict pulmonary hypertension.

Design: Prospective observational study. Setting: Amiens ICU, France. Patients. ICU patients receiving mechanical ventilation. Interventions: In 40 patients, we simultaneously recorded Doppler echocardiography variables (including tricuspid regurgitation and pulmonary regurgitation) and invasive central venous pressure, systolic pulmonary artery pressure, diastolic pulmonary artery pressure, and mean pulmonary artery pressure.

Measurements and Main Results: Systolic pulmonary artery pressure assessed from the tricuspid regurgitation derived maximal pressure gradient added to the central venous pressure demonstrated the best correlation with the invasive systolic pulmonary artery pressure (r = 0.87) with a small bias (–3 mm Hg) and a precision of 9 mm Hg. A Doppler echocardiography systolic pulmonary artery pressure greater than 39 mm Hg predicted pulmonary hypertension (mean pulmonary artery pressure ≥ 25 mm Hg) with 100% sensitivity and specificity. Tricuspid regurgitation maximal velocity greater than 2.82 m/s as well as tricuspid regurgitation pressure gradient greater than 32 mm Hg predicted the presence of pulmonary hypertension. Pulmonary regurgitation was recorded in 10 patients (25%). No correlation was found between pulmonary regurgitation velocities and either mean pulmonary artery pressure or diastolic pulmonary artery pressure. Pulmonary acceleration time less than 57 ms and isovolumic relaxation time less than 40 ms respectively predicted pulmonary hypertension 100% of the time and had a 100% negative predictive value. Conclusions: Tricuspid regurgitation maximal velocity pressure gradient added to invasive central venous pressure accurately estimates systolic pulmonary artery pressure and mean pulmonary artery pressure in ICU patients receiving mechanical ventilation and may predict pulmonary hypertension.

Moderate and Severe Acute Respiratory Distress Syndrome: Hemodynamic and Cardiac Effects of an Open Lung Strategy With Recruitment Maneuver Analyzed Using Echocardiography*

Moderate and Severe Acute Respiratory Distress Syndrome: Hemodynamic and Cardiac Effects of an Open Lung Strategy With Recruitment Maneuver Analyzed Using Echocardiography*

 by Mercado, Pablo; Maizel, Julien; Kontar, Loay; Nalos, Marek; Huang, Stephen; Orde, Sam; McLean, Anthony; Slama, Michel  

Critical Care Medicine: October 2018 - Volume 46 - Issue 10 - p 1608–1616

Objectives: Open lung ventilation with a recruitment maneuver could be beneficial for acute respiratory distress syndrome patients. However, the increased airway pressures resulting from the recruitment maneuver may induce cardiac dysfunction, limiting the benefit of this maneuver. We analyzed the effect of a recruitment maneuver and decremental positive end-expiratory pressure titration on cardiac function.

Settings: Medical ICU Amiens, France.

Patients: Twenty patients with moderate to severe acute respiratory distress syndrome Interventions: Patients underwent a stepwise recruitment maneuver with respiratory evaluation and echocardiography assessment of cardiac function including longitudinal strain at baseline, peak positive end-expiratory pressure of recruitment maneuver (positive end-expiratory pressure 40 cm H2O), and at “optimal” positive end-expiratory pressure. The patients were divided into two groups based on change on the PaO2/FIO2 ratio (nonresponders < 50%; responders ≥ 50%). 

Measurements and Main Results: At peak positive end-expiratory pressure during the recruitment maneuver, the arterial pressure, cardiac output, left ventricular size decreased and right ventricular size increased. The left ventricular ejection fraction decreased from 60% ± 13% to 48% ± 18% (p = 0.05). Both left and right ventricular global longitudinal strain were impaired (–15.8% ± 4.5% to –11% ± 4.7% and –19% ± 5% to –14% ± 6% [p = 0.05] respectively). Fifty percent of patients were nonresponders and demonstrated a lower hemodynamic tolerance to the recruitment maneuver than responders. Optimal positive end-expiratory pressure was 14 ± 5 cm H2O (vs 11 ± 4 cm H2O at baseline), and PaO2/FIO2 ratio increased from 111 ± 25 to 197 ± 89 mm Hg (p < 0.0001). All hemodynamic variables returned to their baseline value after the recruitment maneuver despite a higher positive end-expiratory pressure.

Conclusions: An open lung strategy with a stepwise recruitment maneuver permitted a higher positive end-expiratory pressure and improved oxygenation without any cardiac impairment. The recruitment maneuver was associated with mild and transient, cardiac dysfunction, with nonresponders demonstrating poorer tolerance.