Reproducibility of point-of-care ultrasonography for central vein diameter measurement: Separating image acquisition from interpretation

Temporal Changes in Electrolytes, Acid-Base, QTc Duration, and Point-of-Care Ultrasound during Inpatient Hemodialysis Sessions

Background

Of the more than 550,000 patients receiving maintenance hemodialysis (HD) in the United States, each has an average of 1.6 admissions annually (>880,000 inpatient HD sessions). Little is known about the temporal changes in laboratory values, ECGs, and intravascular and extravascular volume during inpatient HD sessions.

Methods

In this prospective cohort study of hospitalized HD patients, we assessed intradialytic laboratory values (metabolic panels, blood gases, ionized calcium levels), ECGs, and sonographic measures of volume status.

Results

Among 30 participants undergoing HD (mean age 62 years; 53% men, 43% Black) laboratory values had the largest changes in the first hour of HD. There was no significant change in ionized calcium levels pre- to post-HD (change: -0.01±0.07, P=0.24); 12 of 30 and 17 of 30 patients had levels below the lower reference limit at the beginning and end of HD, respectively. The mean pH increased pre- to post-HD (change: 0.06±0.04, P<0.001); 21 of 30 had a pH above the upper reference limit post-HD. There was a trend toward longer median QTc duration from pre- to post-HD (change: 7.5 msec [-5 msec, 19 msec], P=0.07). The sum of B lines on lung ultrasound decreased from pre- to post-HD (median decrease: 3 [1, 7], P<0.01). The collapsibility index of the inferior vena cava increased pre- to post-HD (median increase: 4.8% [1.5%, 13.4%], P=0.01), whereas internal jugular vein diameter did not change (P=0.24).

Conclusions

Among hospitalized patients undergoing HD, we found dynamic changes in laboratory values, QTc duration, and volume status. Further research is required to assess whether HD prescriptions can be tailored to alter these variations to potentially improve patient outcomes.

Role of Internal Jugular Venous Ultrasound in suspected or confirmed Heart Failure: A Systematic Review

BACKGROUND

Few data are available on the use of internal jugular vein (IJV) ultrasound parameters to assess central venous pressure and clinical outcomes among patients with suspected or confirmed heart failure (HF).

METHODS

We performed electronic searches on PubMed, The Cochrane Library, EMBASE, EBSCO, Web of Science, and CINAHL databases from the inception through January 9, 2021, to identify studies evaluating the accuracy and reliability of the IJV ultrasound parameters and exploring its correlation with central venous pressure and clinical outcomes in adult patients with suspected or confirmed acutely decompensated HF. The studies' report quality was assessed by Quality Assessment of Diagnostic Accuracy Studies-2 scale.

RESULTS

A total of 11 studies were eligible for final analysis (n = 1481 patients with HF). The studies were segregated into 3 groups: (1) the evaluation of patients presenting to the emergency department with dyspnea, (2) the evaluation of patients presenting to the HF clinic for follow-up, and (3) the evaluation of hospitalized patients with acutely decompensated HF or undergoing right heart catheterization. US parameters included IJV height, IJV diameter, IJV diameter ratio, IJV cross-sectional area, respiratory compressibility index, and compression compressibility index.

CONCLUSIONS

The findings of this systematic review suggest a significant role for ultrasound interrogation of the IJV in evaluation of patients in the emergency department presenting with dyspnea, in the outpatient clinic for poor clinical outcomes in HF, and in determining the timing of discharge for patients admitted with acutely decompensated HF. Further studies are warranted for testing the reliability of the reported ultrasound indices.

Development of a Deep Learning Network to Classify Inferior Vena Cava Collapse to Predict Fluid Responsiveness

OBJECTIVES

To create a deep learning algorithm capable of video classification, using a long short-term memory (LSTM) network, to analyze collapsibility of the inferior vena cava (IVC) to predict fluid responsiveness in critically ill patients.

METHODS

We used a data set of IVC ultrasound (US) videos to train the LSTM network. The data set was created from IVC US videos of spontaneously breathing critically ill patients undergoing intravenous fluid resuscitation as part of 2 prior prospective studies. We randomly selected 90% of the IVC videos to train the LSTM network and 10% of the videos to test the LSTM network's ability to predict fluid responsiveness. Fluid responsiveness was defined as a greater than 10% increase in the cardiac index after a 500-mL fluid bolus, as measured by bioreactance.

RESULTS

We analyzed 211 videos from 175 critically ill patients: 191 to train the LSTM network and 20 to test it. Using standard data augmentation techniques, we increased our sample size from 191 to 3820 videos. Of the 175 patients, 91 (52%) were fluid responders. The LSTM network was able to predict fluid responsiveness moderately well, with an area under the receiver operating characteristic curve of 0.70 (95% confidence interval [CI], 0.43-1.00), a positive likelihood ratio of infinity, and a negative likelihood ratio of 0.3 (95% CI, 0.12-0.77). In comparison, point-of-care US experts using video review offline and manual diameter measurement via software caliper tools achieved an area under the receiver operating characteristic curve of 0.94 (95% CI, 0.83-0.99).

CONCLUSIONS

We demonstrated that an LSTM network can be trained by using videos of IVC US to classify IVC collapse to predict fluid responsiveness. Our LSTM network performed moderately well given the small training cohort but worse than point-of-care US experts. Further training and testing of the LSTM network with a larger data sets is warranted.

Performance of a 25% Inferior Vena Cava Collapsibility in Detecting Fluid Responsiveness When Assessed by Novice Versus Expert Physician Sonologists

OBJECTIVES

Inferior vena cava collapsibility (cIVC) measured by point-of-care ultrasound (POCUS) has been proposed as a noninvasive means of assessing fluid responsiveness. We aimed to prospectively evaluate the performance of a 25% cIVC cutoff value to detect fluid responsiveness among spontaneously breathing intensive care unit (ICU) patients when assessed with POCUS by novice versus expert physician sonologists.

METHODS

Prospective observational study of spontaneously breathing ICU patients. Fluid responsiveness was defined as a >10% increase in cardiac index following a 500 mL fluid bolus, measured by bioreactance. Novice sonologist measured cIVC with POCUS. Their measurements were later compared to an expert physician sonologist who independently reviewed the POCUS images and assessed cIVCs.

RESULTS

Of the 85 participants, 44 (52%) were fluid responders. A 25% cIVC cutoff value performed better when assessed by expert sonologists than novice physician sonologists (receiver-operator characteristic curve, ROC = 0.82 [0.74-0.88] vs ROC = 0.69 [0.60-0.77]).

CONCLUSIONS

A 25% cIVC cutoff value measured by POCUS detects fluid responsiveness. However, the experience of the physician sonologist affects test performance and should be considered when interpreting and clinically using cIVC to direct intravenous fluid resuscitation.

Limited agreement between two noninvasive measurements of blood volume during fluid removal: ultrasound of inferior vena cava and finger-clip spectrophotometry of hemoglobin concentration

OBJECTIVE

Plots of blood volume measurements over time (profiles) may identify euvolemia during fluid removal for acute heart failure. We assessed agreement between two noninvasive measurements of blood volume profiles during mechanical fluid removal, which exemplifies the interstitial fluid shifts that occur during diuretic-induced fluid removal.

APPROACH

During hemodialysis we compared change in maximum diameter of the inferior vena cava by ultrasound ([Formula: see text]) to change in relative blood volume derived from capillary hemoglobin concentration from finger-clip spectrophotometry (RBV_SpHb). We grouped profiles of these measurements into three distinct shapes using an unbiased, data-driven modeling technique.

METHODS

Fifty patients who were not in acute heart failure underwent a mean of five paired measurements while an average of 1.3 liters of fluid was removed over 2 h during single hemodialysis sessions. [Formula: see text] changed  -1.0 mm (95% CI  -1.9 to  -0.2 mm) and the RBV_SpHb changed  -1.1% (95% CI  -2.7 to  +0.5%), but these changes were not correlated (r  -0.04, 95% CI  -0.32 to  +0.24). Nor was there agreement between categorization of profiles of change in the two measurements (kappa  -0.1, 95% CI  -0.3 to  +0.1).

SIGNIFICANCE

[Formula: see text] and RBV_SpHb estimates of blood volume do not agree during mechanical fluid removal, likely because regional changes in blood flow and pressure modify IVC dimensions as well as changes total blood volume.