A pocket-sized hand held ultrasound system for intraoperative transthoracic echocardiography by anaesthesiologists: A feasibility study

Cardiac and vascular point-of-care ultrasound: current situation, problems, and future prospects

Although clinical application of ultrasound to the heart has a history of about 80 years, its big turning point was the emergence of a portable ultrasound diagnostic machine. As a result, the place, where echocardiography is performed widely spread outside the examination room, and the people who perform echocardiography have also greatly increased. Emergency physicians, anesthesiologists, and primary care physicians became interested in echocardiography and started using it. Such ultrasound examinations performed by a doctor for assessment of disease condition, management, or guidance of treatment at bedside has been called point-of-care ultrasound (POCUS). Cardiac POCUS is divided into a focused cardiac ultrasound examination (FoCUS) and limited echocardiography. The former is performed by non-experts in echocardiography, such as emergency physicians and anesthesiologists, whereas the latter is usually performed by cardiologists who are experts in echocardiography. FoCUS has an established protocol and evaluation method, and evidence to prove its effectiveness is accumulating. In addition, the COVID-19 outbreak reaffirmed the importance of POCUS. Although FoCUS is becoming popular in Japan, an educational program has not been established, and discussion on how to educate medical students and residents will be necessary. Even if POCUS in cardiovascular medicine becomes widespread, auscultation will still be necessary. Rather, adding cardiac and vascular POCUS to inspection, palpation, and auscultation in the flow of physical examinations will benefit patients greatly.

Subcostal TAPSE measured by anatomical M-mode: prospective reliability clinical study in critically ill patients

BACKGROUND

Tricuspid annular plane systolic excursion (TAPSE), evaluated from a four-chamber apical view, is an echocardiographic parameter for the detection of right ventricular systolic dysfunction (RVD). We decided to assess the reliability of TAPSE measured from subcostal view (sTAPSE) by anatomical M-mode imaging (AMM) for evaluation of right ventricular systolic function and prediction of RVD in the critically ill patients by comparison with other echocardiographic parameters.

METHODS

We conducted an observational, prospective clinical study in 100 patients hospitalized in the intensive care unit. TAPSE, doppler tissue imaging-derived tricuspid lateral annular systolic velocity (DTI-S´ wave), two-dimensional fraction area change (2D FAC) and DTI-right ventricular index of myocardial performance (DTI-RIMP) were measured by transthoracic echocardiography. A subcostal four-chamber view was recorded for sTAPSE measurement. For that purpose, the cursor of AMM was aligned along the direction of the tricuspid lateral annulus movement and the amplitude of the movement was measured.

RESULTS

In a group of patients aged 64±16 years with a 31% prevalence of RVD we identified strong correlation between TAPSE and sTAPSE (r=0.963, P<0.001). sTAPSE correlated well with other measures of right ventricular systolic function (DTI-S´ wave: r=0.765; 2D FAC: r=0.701; DTI-RIMP: r=-0.661, P<0.001, respectively). The value of sTAPSE ≤15 mm predicted the presence of RVD defined by TAPSE with a sensitivity of 94.7% and specificity of 100.0%.

CONCLUSIONS

The sTAPSE measured by AMM in a population of critically ill patients has been found to be a reliable parameter of right ventricular systolic function and predicted RVD with high reliability.

Automated Identification and Localization of the Inferior Vena Cava Using Ultrasound: An Animal Study

Ultrasound measurement of the inferior vena cava (IVC) is widely implemented in the clinic. However, the process is time consuming and labor intensive, because the IVC diameter is continuously changing with respiration. In addition, artificial errors and intra-operator variations are always considerable, making the measurement inconsistent. Research efforts were recently devoted to developing semiautomated methods. But most required an initial identification of the IVC manually. As a first step toward fully automated IVC measurement, in this paper, we present an intelligent technique for automated IVC identification and localization. Forty-eight ultrasound data sets were collected from eight pigs, each of which included two frames in B-mode and color mode (C-mode) collected at the inspiration, and two cine loops in B-mode and C-mode. Static and dynamic automation algorithms were applied to the data sets for identifying and localizing the IVC. The results were evaluated by comparing with the manual measurement of experienced clinicians. The automated approaches successfully identified the IVC in 47 cases (success rate: 97.9%). The automated localization of the IVC is close to the manual counterpart, with the difference within one diameter. The automatically measured diameters are close to those measured manually, with most differences below 15%. It is revealed that the proposed method can automatically identify the IVC with high success rate and localize the IVC with high accuracy. But the study with high accuracy was conducted under good control and without considering difficult cases, which deserve future explorations. The method is a first step toward fully automated IVC measurement, which is suitable for point-of-care applications.