Evaluation of System Modelling Techniques for Waste Identification in Lean Healthcare Applications.

PURPOSE: Waste identification plays a vital role in lean healthcare applications. While the value stream map (VSM) is among the most commonly used tools for waste identification, it may be limited to visualize the behaviour of dynamic and complex healthcare systems. To address this limitation, system modelling techniques (SMTs) can be used to provide a comprehensive picture of various system-wide wastes. However, there is a lack of evidence in the current literature about the potential contribution of SMTs for waste identification in healthcare processes. METHODS: This study evaluates the usability and utility of six types of SMTs along with the VSM. For the evaluation, interview-based questionnaires were conducted with twelve stakeholders from the outpatient clinic at the Heart and Vascular Institute at Cleveland Clinic Abu Dhabi. RESULTS: VSM was found to be the most useful diagram in waste identification in general. However, some SMTs that represent the system behaviour outperformed the VSM in identifying particular waste types, e.g., communication diagram in identifying over-processing waste and flow diagram in identifying transportation waste. CONCLUSION: As behavioural SMTs and VSM have unique strengths in identifying particular waste types, the use of multiple diagrams is recommended for a comprehensive waste identification in lean. However, limited resources and time, as well as limited experience of stakeholders with SMTs, may still present obstacles for their potential contribution in lean healthcare applications.

Three-dimensional echocardiographic analysis of right atrial volume in normal and abnormal hearts: comparison of biplane and multiplane methods.

BACKGROUND: Although right atrial size has clinical and prognostic importance, few data exist regarding the optimal three-dimensional echocardiography (3DE) method for assessing right atrial volume (RAV). While measuring RAV in multiple planes may improve the accuracy, it also increases analysis time. The purpose of this study was to determine the minimum number of planes required for optimal assessment of RAV, using eight-plane 3DE measurements as a reference standard. METHODS: 3DE was performed in 70 subjects (35 normal and 35 abnormal). 3DE RAV was obtained from three methods by tracing right atrial endocardial borders at ventricular end-systole in two orthogonal planes (two-plane), four equiangular planes (four-plane), and eight equiangular planes (eight-plane) in each subject. The time required for analysis was recorded for each method. RESULTS: Based on eight-plane RAV, mean RAV was 41 ± 13 mL in the normal group, and 82 ± 35 mL in the abnormal group. The average time for two-plane, four-plane, and eight-plane analysis was 69 ± 29, 118 ± 29, and 203 ± 37 s, respectively (P < 0.001 for comparisons between all groups). Four-plane approach had close agreement with eight-plane (2.6% underestimation for total group), while two-plane measurement underestimated RAV by an average of 19% for the total group, compared to eight-plane. CONCLUSION: Four-plane measurement of RAV shows good agreement with eight-plane measurement, while reducing the time required for analysis. Compared to eight-plane analysis, biplane measurement of RAV can result in underestimation of RAV, particularly in abnormal subjects with right atrial enlargement and remodeling.

3D echocardiography to evaluate right atrial pressure in acutely decompensated heart failure correlation with invasive hemodynamics.

OBJECTIVES: This study examined the utility of 3-dimensional right atrial volume index (3D-RAVi), combined with 2-dimensional echocardiographic (2DE) parameters, for the identification of elevated right atrial pressure (RAP) in patients with heart failure. BACKGROUND: Accurate noninvasive determination of RAP is clinically important for the management of patients with heart failure. Although 2DE methods have been used to noninvasively estimate RAP, the accuracy of these parameters has limitations when estimating RAP in an individual patient. Three-dimensional echocardiography (3DE) provides tomographic imaging of right atrial volume that may be helpful in refining the noninvasive assessment of hemodynamics in patients with heart failure. METHODS: 2DE and 3DE studies were examined in 40 initial patients who were admitted for acutely decompensated heart failure. Simultaneous pulmonary artery catheter monitoring was performed. The relationship between echocardiographic parameters and RAP was examined in this derivation group. The findings from the derivation group were then prospectively tested in a validation group of 40 additional patients. RESULTS: Mean RAP was 11 ± 5 mm Hg (range 2 to 22 mm Hg). 3D-RAVi correlated with RAP (r = 0.51, p < 0.001), whereas 2-dimensional right atrial volume index did not. Inferior vena cava (IVC) diameter ≥2 cm and IVC respirophasic collapse <40% also correlated with RAP (p < 0.001 and p = 0.028, respectively). Based on receiver-operator characteristic curve analysis, 3D-RAVi ≥35 ml/m(2) was the optimal 3D-RAVi cutpoint for identifying RAP >10 mm Hg. The value of 3D-RAVi ≥35 ml/m(2), combined with IVC measures, for predicting RAP >10 mm Hg was prospectively tested in the validation group. 3D-RAVi ≥35 ml/m(2) in combination with IVC ≥2 cm had a high accuracy (88%) for identifying RAP >10 mm Hg and had a higher accuracy than the combination of IVC ≥2 cm and IVC collapse <40% (accuracy: 68%, p = 0.038). CONCLUSIONS: In patients with heart failure, 3D-RAVi in conjunction with IVC parameters has a high accuracy for detection of elevated RAP. The addition of 3D-RAVi to 2DE methods may be helpful in the noninvasive estimation of right atrial pressure.