Computational protocol: Transthoracic ultrasound assessment of B-lines for identifying the increment of extravascular lung water in shock patients requiring fluid resuscitation

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Protocol publication

[…] We conducted a prospective, observational study from July 2010 to December 2010. We consecutively enrolled shock patients admitted to medical ICU of a university hospital. The inclusion criteria were patients at age ≥18 years old with the presence of shock and requiring fluid therapy. The shock syndromes were defined by mean arterial pressure <65 mmHg with evidence of poor tissue perfusion. The exclusion criteria were patients with pleural diseases, post-operative heart or lung surgery, those unable to perform ultrasound and those who refused to sign a consent form. In patients with mechanical ventilation, the tidal volume was set as 8-10 ml/kg and kept constant throughout the study period. Positive end-expiratory pressure was set according to the lung problem. The FiO2 was adjusted to keep PaO2 in normal range. The transthoracic ultrasounds were performed by an experienced physician. The first ultrasound was performed at admission to assess the baseline number of the B-lines. The repeated ultrasound was performed within 48 h to assess the number of the B-lines after fluid resuscitation. The patient's characteristics, hemodynamic data, PaO2/FiO2 ratio (P/F ratio), chest radiographic score and total fluid volume were recorded at the same time as performing transthoracic ultrasound.The study was approved by the institute's Human Research Committee Institutional Review Board and followed the National Helsinki Committee guidelines. All patients or their next of kin gave written informed consent.To assess the B-lines, we used commercially available portable device; Sonosite M-turbo (Sonosite Inc.; Bothell, WA, USA) 10-15 MHz probe. The B-lines were defined as vertical echogenic, wedge-shaped, dynamic lines with narrow origin starting from the pleural line and extending to the edge of the screen []. We assessed the B-lines of patients in the supine position by taking the ultrasound probe initially from the second intercostal space (ICS) to the fifth ICS on bilateral hemithorax along the mid-clavicular line (MCL), anterior axillary line (AAL) and mid-axillary line (MAL) respectively and to the fourth ICS only for assessment along the MCL of left hemithorax. We adjusted the image depth to the deepest level before recording. All images were saved as video files and renamed in codes set by the operator. A total of 23 10-s interval video files was obtained per patient and sent to two observers in two separate file sets for interpretation.The video files were independently interpreted by two observers who were blinded from the patient data, to verify the number of B-lines. If the numbers of B-lines counted by two observers were not concordant, the consensus number would be used. The inter-observer correlation between two independent observers in a set of 14 consecutive cases was very high (r = 0.92, P < 0.01). The numbers of B-lines were finally derived as: (1) Total B line score (TBS) calculated by the sum of all B lines in all 23 points of assessment, (2) B + area defined as the number of points of assessment containing at least three B-lines; and (3) B-lines calculated by the differences of a number of B-lines at follow up period (TFL) and at admission (T0). Chest radiography was done at the same time point as ultrasound procedure. We used radiologic score (RS) to assess EVLW.[] The RS was scored by an experienced chest radiologist, who was blinded from the patient data. The score ranged from 0 to 111 as shown in .Patient characteristics, TBS, B + area, chest RS and fluid volume were expressed as the mean value ± standard deviation or percentage. Comparison of ultrasonographic data between two points of time were analyzed by paired sample t-test. Correlations between changing of B line and three variables including the amount of fluid replacement volume, oxygenation and RS were analyzed by Pearson's correlation. A P ≤ 0.05 was considered as statistical significance. The statistical analysis was performed using SPSS software version 15.0. […]

Pipeline specifications

Software tools AAL, SPSS
Applications Miscellaneous, Magnetic resonance imaging
Organisms Homo sapiens
Diseases Lymphoma, B-Cell