P5629Feasibility of teaching patients self-assessment of inferior vena cava operating a portable ultrasound device

Abstract

Background: The size and respiratory variation of inferior vena cava (IVC) is an efficient surrogate of the intravascular volume and is assessed by ultrasound (US). Data exists that IVC status at patient discharge from hospitalization due to heart failure decompensation is a predictor of re-hospitalization. We hypothesize that patients can perform a focused US study on themselves to assess IVC after a brief training on the use of pocket-size US devices (PUD). The data can be used to tailor the medical treatment to the patient. Purpose: We aim to assess the feasibility of teaching the US technique of self-examination of the IVC to subjects without any experience and knowledge of US in a short time. Methods: A prospective study was conducted among healthy volunteers with no previous knowledge of US, who received a 30-minute lecture followed by 30 min-utes of hands-on practice of self-examination of the IVC operating a PUD. After a week, the volunteers performed a self-study of the IVC focused on the acquisition of images that can be used to measure IVC size and assess its respiratory varia-tion; the images were recorded and stored in the PUD. A second US study using PUD was done by a cardiologist blinded to the previous study and also recorded the images for future evaluation. Another cardiologist performed measurements of the IVC size on the recorded clips and assessed its respiratory variation. The images were scored as follows: 0 no image provided and one point for each of the following conditions: faint image but unable to perform measurements; able to assess IVC respiratory variation; able to measure IVC size. The score ranged from 0 to a maximum of 3. Results: The study included 30 volunteers, aged 54±21 years, 65% females. Af-ter the practical training 2 volunteers refused to continue with the study because they were unable to hold the transducer in the subcostal area with gentle pres-sure. Then 28 volunteers performed their IVC self-assessment. Volunteer and car-diologist score of the IVC images was 2.2±0.8 and 2.8±0.1, respectively (p=0.16). There were 18 volunteers ≥65 years. The score of this group was 1.4±0.6, lower than the score of the volunteers younger of 65 years: 2.3±0.3 (p=0.027). Although not statistically significant, by univariant analysis the only parameter that had an impact on volunteers results was age. In those cases (17 out of 28) that IVC size could be measured from the images obtained by the volunteers' and cardiologists' study, the correlation was good (0.67). IVC respiratory variation was able to be evaluated in 25/28 cases done by the cardiologist but in only 13/28 of self-studies. Conclusions: The feasibility of teaching an adult population the US technique of self-assessment of the IVC after a brief training is high. Advanced age influenced adversely on the IVC image quality. Evaluation of IVC size by an independent reader of self-US studies is possible with acceptable precision.