Monitoring Patients With Shortness of Breath With Repeated Ultrasound Examinations

Design: Multicenter, randomized, controlled, open-label, and pragmatic trial.

Settings: Several different emergency departments (EDs) in Denmark.

Study flow: After arrival, the patients are screened according to eligibility criteria. If patients meet the inclusion criteria and informed consent is obtained, the patients are randomly assigned to one of two groups. In both groups, the patients received standard evaluation, e.g., blood samples, physical examination, arterial blood gas, and in addition ultrasound examination of the heart and the lungs. In the intervention group, the patients are further examined with serial ultrasound scans of the heart and the lungs after two and four hours after the initial evaluation.

In the course of admittance, the patients will have there baseline characteristics recorded together with the ultrasound findings, symptoms, and vitals. Symptoms will be recorded at a verbal dyspnea symptom scale (VDS) from 0-10.

All data will be registered at the same time points to make comparisons: At 1, 2, 4 and after 5 hours.

Sample size: This is calculated from the primary outcome and with an assumption of a power of 80%, type 1-error of 5%, and 10% dropouts. The calculations are based on previous studies using the VDS on patients with acute dyspnea. The sample size is 103 patients in each group.

Statistical analysis: Baseline characteristics will be summarized and divided into the intervention and control group. Continuous variables will be summarized as means and standard deviation (SD) or medians and interquartile range (IQR) depending on the distribution of the variable. For categorical variables, frequencies and percentages will be reported.

The primary outcome - change in dyspnea on VDS - will be compared between the two groups to detect any difference. Pairwise comparisons of VDS will be made at the same time points in both groups.

The secondary outcomes: Length of stay, death, and the number of readmissions will be compared between the two groups to detect a difference. Time-to-event (dead or readmission) will be visualized with Kaplan Meier curves.

In the case of lost to follow-up or other reasons for missing data both intention-to-treat and per-protocol analysis will be used.

The secondary outcomes in the interventions group: The dynamic changes in inferior vena cava collapsibility index (IVC-CI) and the sum of B-lines will be expressed as means and SD or median and IQR depending on the distribution of the data and compared between the different time points. Furthermore, IVC-CI and the sum of B-lines will be compared to vitals and VDS-score to detect a correlation.

The inter- and intraobserver variability regarding the focused ultrasound will be accessed.

Data management: The registered data on each patient will be recorded and securely stored in an encrypted, logged, and password-protected database called REDCap. All adjustments in the database are logged. The patients are anonymized.

Inclusion criteria

• Participants should be 18 years or older
• Presented at the ED with shortness of breath (asking the patient upon arrival in the triage what their primary complaint is for a referral to an emergency department)
• Written informed consent obtained from the patient

Exclusion criteria

• Patients with dyspnea primary admitted because of a trauma