Applications of minimally invasive cardiac output monitors

Non-Invasive Continuous Measurement of Haemodynamic Parameters-Clinical Utility

The evaluation and monitoring of patients’ haemodynamic parameters are essential in everyday clinical practice. The application of continuous, non-invasive measurement methods is a relatively recent solution. CNAP, ClearSight and many other technologies have been introduced to the market. The use of these techniques for assessing patient eligibility before cardiac procedures, as well as for intraoperative monitoring is currently being widely investigated. Their numerous advantages, including the simplicity of application, time- and cost-effectiveness, and the limited risk of infection, could enforce their further development and potential utility. However, some limitations and contradictions should also be discussed. The aim of this paper is to briefly describe the new findings, give practical examples of the clinical utility of these methods, compare them with invasive techniques, and review the literature on this subject.

Fluid Administration in Emergency Room Limited by Lung Ultrasound in Patients with Sepsis: Protocol for a Prospective Phase II Multicenter Randomized Controlled Trial

Background

Sepsis remains a major health challenge with high mortality. Adequate volume administration is fundamental for a successful outcome. However, individual fluid needs differ between patients due to varying degrees of systemic vasodilation, circulatory flow maldistribution, and increased vascular permeability. The current fluid resuscitation practice has been questioned. Fluid overload is associated with higher mortality in sepsis. A sign of fluid overload is extravascular lung water, seen as B lines in lung ultrasound. B lines correlate inversely with oxygenation (measured by a ratio of the partial pressure of arterial oxygen to the fraction of inspired oxygen ie, PaO2/FiO2). Thus, B lines seen by bedside ultrasound may have a role in guiding fluid therapy.

Objective

We aim to evaluate if fluid administration guided by lung ultrasound in patients with sepsis in emergency departments will lead to better oxygenation and patient outcomes than those in the standard therapy.

Methods

A phase II, multicenter, randomized, open-label, parallel-group, superiority trial will be performed. Patients will be recruited at emergency departments of the participating centers. A total of 340 patients will be randomly allocated to the intervention or standard-of-care group (30mL/kg). The intervention group will receive ultrasound-guided intravenous fluid until 3 B lines appear. The primary outcome will be oxygenation (measured as PaO2/FiO2 ratio) at 48 hours after starting intravenous fluid administration. Secondary outcomes will be patients’ outcome parameters, including oxygenation after 15 mL/kg fluid at 6, 12, 24, and 48 hours; sepsis progress through Sequential Organ Failure Assessment (SOFA) scores; pulmonary edema evaluation; and 30-day mortality.

Results

The trial will be conducted in accordance with the Declaration of Helsinki. Institutional review board approval will be sought after the participating sites are selected. The protocol will be registered once the institutional review board approval is granted. The trial duration is expected to be 1.5-2.5 years. The study is planned to be performed from 2021 to 2022, with enrollment starting in 2021. First results are expected in 2022. Informed written consent will be obtained before the patient’s enrollment in the study. An interim analysis and data monitoring will ensure the patient safety. The results will be published in a peer-reviewed journal and discussed at international conferences.

Conclusions

This is a protocol for a randomized control trial that aims to evaluate the role of bedside ultrasound in guiding fluid therapy in patients with sepsis via B lines evaluation.

International Registered Report Identifier (IRRID)

PRR1-10.2196/15997

Correlations between pulmonary artery pressures and inferior vena cava collapsibility in critically ill surgical patients: An exploratory study

INTRODUCTION

As pulmonary artery catheter (PAC) use declines, search continues for reliable and readily accessible minimally invasive hemodynamic monitoring alternatives. Although the correlation between inferior vena cava collapsibility index (IVC-CI) and central venous pressures (CVP) has been described previously, little information exists regarding the relationship between IVC-CI and pulmonary artery pressures (PAPs). The goal of this study is to bridge this important knowledge gap. We hypothesized that there would be an inverse correlation between IVC-CI and PAPs.

METHODS

A post hoc analysis of prospectively collected hemodynamic data was performed, examining correlations between IVC-CI and PAPs in a convenience sample of adult Surgical Intensive Care Unit patients. Concurrent measurements of IVC-CI and pulmonary arterial systolic (PAS), pulmonary arterial diastolic (PAD), and pulmonary arterial mean (PAM) pressures were performed. IVC-CI was calculated as ([IVCmax - IVCmin]/IVCmax) × 100%. Vena cava measurements were obtained by ultrasound-credentialed providers. For the purpose of correlative analysis, PAP measurements (PAS, PAD, and PAM) were grouped by terciles while the IVC-CI spectrum was divided into thirds (<33, 33-65, ≥66).

RESULTS

Data from 34 patients (12 women, 22 men, with median age of 59.5 years) were analyzed. Median Acute Physiologic Assessment and Chronic Health Evaluation II score was 9. A total of 76 measurement pairs were recorded, with 57% (43/76) obtained in mechanically ventilated patients. Correlations between IVC-CI and PAS (rs = -0.334), PAD (rs = -0.305), and PAM (rs = -0.329) were poor. Correlations were higher between CVP and PAS (R2 = 0.61), PAD (R2 = 0.68), and PAM (R2 = 0.70). High IVC-CI values (≥66%) consistently correlated with measurements in the lowest PAP ranges. Across all PAP groups (PAS, PAD, and PAM), there were no differences between the mean measurement values for the lower and middle IVC-CI ranges (0%-65%). However, all three groups had significantly lower mean measurement values for the ≥66% IVC-CI group.

CONCLUSIONS

Low PAS, PAD, and PAM measurements show a reasonable correlation with high IVC-CI (≥66%). These findings are consistent with previous descriptions of the relationship between IVC-CI and CVP. Additional research in this area is warranted to better describe the hemodynamic relationship between IVC-CI and PAPs, with the goal of further reduction in the reliance on the use of PACs.

Early interventional therapy for acute massive pulmonary embolism guided by minimally invasive hemodynamic monitoring

AIM

The aim of this study was to investigate the clinical significance of minimally invasive hemodynamic monitoring in the early catheter-based intervention for acute massive pulmonary embolism (PE).

METHODS

A total of 40 cases with acute massive PE were randomized into experimental and control group with 20 cases in each group. In the experimental group, the hemodynamics was monitored via Vigileo/FloTrac system, while echocardiography was used in the control group. Twelve hours after systemic thrombolysis, catheter-based clot fragmentation and local thrombolysis were employed in the experimental group if Vigileo/FloTrac system revealed hemodynamic abnormality. For the control group, the application of catheter was determined by the findings in echocardiography at 24 hours after systemic thrombolysis.

RESULTS

A total of 12 cases in the experimental group underwent catheter therapy successfully while 4 cases in the control group received the same treatment. Compared to the control group, 12 hours after catheter intervention the experimental group had higher PaO2/FIO2 and right ventricular ejection fraction (RVEF) but lower pulmonary artery systolic pressure (PASP), indicating the effectiveness of Vigileo/FloTrac monitoring. The 28-day survival rates were identical between the groups although one patent in the control group died. Both the RVEF and PASP were significantly improved in the experimental group in 6 months compared to the control group.

CONCLUSIONS

In massive PE, hemodynamic monitoring via Vigileo/FloTrac system might be useful in the decision making for catheter intervention after systemic thrombolysis and might improve the outcomes for patients.

Perioperative risk factors for prolonged mechanical ventilation after liver transplantation due to acute liver failure

Background

Acute liver failure (ALF) is a rapidly progressing and fatal disease for which liver transplantation (LT) is the only treatment. Posttransplant mechanical ventilation tends to be more prolonged in patients with ALF than in other LT patients. The present study examined the clinical effects of prolonged posttransplant mechanical ventilation (PMV), and identified risk factors for PMV following LT for ALF.

Methods

We reviewed data of patients undergoing LT for ALF between January 2005 and June 2011. After grouping patients according to administration of PMV (≥ 24 h), donor and recipient perioperative variables were compared between the groups with and without PMV. Potentially significant factors (P < 0.1) from the univariate intergroup comparison were entered into a multivariate logistic regression to establish a predictive model for PMV.

Results

Twenty-four (25.3%) of 95 patients with ALF who received PMV had a higher mortality rate (29.2% vs 11.3%, P = 0.038) and longer intensive care unit stay (12.9 ± 10.4 vs 7.1 ± 2.7 days, P = 0.012) than patients without PMV. The intergroup comparisons revealed worse preoperative hepatic conditions, more supportive therapy, and more intraoperative fluctuations in vital signs and less urine output in the with- compared with the without-PMV group. The multivariate analysis revealed that preoperative hepatic encephalopathy (≥ grade III), intraoperative blood pressure fluctuation, and oliguria (< 0.5 ml/kg/h) were independent risk factors for PMV.

Conclusions

PMV was associated with deleterious outcomes. Besides care for known risk factors including hepatic encephalopathy, meticulous attention to managing intraoperative hemodynamic circulatory status is required to avoid PMV and improve the posttransplant prognosis in ALF patients.