Correlation of echocardiographic parameters in prone and supine positions in normal adults using a novel approach

The preferable position for quantifying left ventricular diameter by transthoracic echocardiography

BACKGROUND

In quantifying left ventricular (LV) diameter, which position for echocardiographic measurements, mitral valve tip level (MV-tip) or LV mid level (LV-mid), more accurately represents the LV volume is unclear. Furthermore, which factor affects the measurement error also has not been elucidated.

METHODS

We enrolled 150 patients without myocardial infarction and local asynergy who underwent echocardiography and cardiac magnetic resonance imaging (CMRI). Echocardiographic LV diastolic diameter (LVDD) and LV systolic diameter (LVDS) were measured at both MV-tip and LV-mid, and the LV end-diastolic volume (LVEDV) and end-systolic volume (LVESV) were quantified using CMRI. We quantified the degree of aortic wedging as the angle between the anterior wall of the aorta and the ventricular septal surface (ASA).

RESULTS

The average LVDD was smaller and average LVDS larger when measured at the MV-tip than at the LV-mid. In regression analyses, the correlation coefficient between LVDD and LVEDV was larger at LV-mid (R = 0.89) than at MV-tip (R = 0.82), and the correlation coefficient between LVDS and LVESV also larger at LV-mid (R = 0.93) than MV-tip (R = 0.87). ASA, Valsalva diameter, left atrial diameter, patient height, and LV mass significantly affected the echocardiographic measurement error, but no factor affected the measurement error when quantifying LVDD at the LV-mid level.

CONCLUSIONS

The echocardiographic LV diameter measured at LV-mid has a stronger correlation with LV chamber size derived from CMRI than measurements at MV-tip. The LVDD measured at the LV-mid level is not affected by other factors.

Use of the cardiac power index to predict fluid responsiveness in the prone position: a proof-of-concept study

BACKGROUND

The primary aim of this proof-of-concept study was to investigate whether the Cardiac Power Index (CPI) could be a novel alternative method to assess fluid responsiveness in the prone position.

METHODS

Patients undergoing scheduled elective lumbar spine surgery in the prone position under general anesthesia were enrolled in the criteria of patients aged 19-75 years with American Society of Anesthesiologists (ASA) physical status I-II. The hemodynamic variables were evaluated before and after changes in posture after administering a colloid bolus (5 mL.kg-1) in the prone position. Fluid responsiveness was defined as an increase in the Stroke Volume Index (SVI) ≥ 10%.

RESULTS

A total of 28 patients were enrolled. In responders, the CPI (median [1/4Q-3/4Q]) decreased to 0.34 [0.28-0.39] W.m-2 (p = 0.035) after the prone position. After following fluid loading, CPI increased to 0.48 [0.37-0.52] W.m-2 (p < 0.008), and decreased SVI (median [1/4Q-3/4Q]) after prone increased from 26.0 [24.5-28.0] mL.m-2 to 33.0 [31.0-37.5] mL.m-2 (p = 0.014). Among non-responders, CPI decreased to 0.43 [0.28-0.53] W.m-2 (p = 0.011), and SVI decreased to 29.0 [23.5-34.8] mL.m-2 (p < 0.009). CPI exhibited predictive capabilities for fluid responsiveness as a receiver operating characteristic curve of 0.78 [95% Confidence Interval, 0.60-0.95; p = 0.025].

CONCLUSION

This study suggests the potential of CPI as an alternative method to existing preload indices in assessing fluid responsiveness in clinical scenarios, offering potential benefits for responders and non-responders.

Echocardiography in Prone Positioned Critically Ill Patients: A Wealth of Information from a Single View

In critically ill patients, standard transthoracic echocardiography (TTE) generally does not facilitate good image quality during mechanical ventilation. We propose a prone-TTE in prone positioned patients, which allows clinicians to obtain a complete apical four-chamber (A-4-C) view. A basic cardiac assessment can be performed in order to evaluate right ventricle function and left ventricle performance, even measuring objective parameters, i.e., tricuspid annular plane systolic excursion (TAPSE); pulmonary artery systolic pressure (PAP), from the tricuspid regurgitation peak Doppler velocity; RV end-diastolic diameter and its ratio to left ventricular end-diastolic diameter; the S’ wave peak velocity with tissue Doppler imaging; the ejection fraction (EF); the mitral annular plane systolic excursion (MAPSE); diastolic function evaluation by the mitral valve; and annular Doppler velocities. Furthermore, by tilting the probe, we can obtain the apical-five-chamber (A-5-C) view, which facilitates the analysis of blood flow at the level of the output tract of the left ventricle (LVOT) and then the estimation of stroke volume. Useful applications of this technique are hemodynamic assessment, titration of fluids, vasoactive drugs therapy, and evaluation of the impact of prone positioning on right ventricle performance and right pulmonary resistances. We believe that considerable information can be drawn from a single view and hope this may be helpful to emergency and critical care clinicians whenever invasive hemodynamic monitoring tools are not available or are simply inconvenient due to clinical reasons.

Transthoracic echocardiography of patients in prone position ventilation during the COVID-19 pandemic: an observational and retrospective study

Mechanical ventilation in prone position is a strategy that increases oxygenation and reduces mortality in severe ARDS. The hemodynamic and cardiovascular assessment of these patients is essential. Transthoracic echocardiography (TTE) is a widely used tool to assess hemodynamics in critical care, but the prone position is thought to limit adequate TTE views and goal-oriented measurements. The aim of this study is to show the feasibility of the hemodynamic assessment by transthoracic echocardiography during prone position ventilation (PPV). This is a retrospective, observational study, carried out in the intensive care unit (ICU) of a tertiary-care center in Buenos Aires, Argentina. We included all the adult patients admitted to the ICU between March 2020 and August 2021 who had a TTE examination in PPV due to ARDS. During the study period, we evaluated by TTE a total of 35 patients requiring PPV. The vast majority of the patients had COVID-19 pneumonia (91.4%). In 33 out of 35 (94.3%) cases, it was able to achieve an adequate apical four chamber view. We assessed qualitatively the systolic function of left ventricle (LV) and right ventricle (RV) in all of the successfully evaluated patients. We measured the RV basal diameter (94.3%), RV/LV ratio (77.1%), tricuspid annular plane systolic excursion (TAPSE) (91.4%), and septal mitral annular plane systolic excursion (MAPSE) (88.5%) in most of them. Also, we quantified the left ventricle outflow tract velocity time integral (LVOT VTI) in a large part (68.5%) of the examinations. Transthoracic echocardiography is a useful tool for the hemodynamic assessment of patients in prone position under mechanical ventilation.