Nurse delivered focused echocardiography to determine intravascular volume status in a deployed maritime critical care unit

Focused echocardiography is increasingly used by clinicians to guide fluid resuscitation. The UK Defence Medical Services (DMS) have adopted focused echocardiography as a tool to guide flow assessment and resuscitation in deployed critical care. We aimed to explore whether two focused echo techniques, namely Inferior Vena Cava (IVC) and Left Ventricular Outflow Tract Velocity Time integer (LVOT VTi) respiratory variability could be taught to a group of critical care nurses without previous exposure to ultrasound imaging. After a five-week program of training, validation was carried out on healthy volunteers. The mentor, an accredited focused echo trainer, and six nurses performed a total of forty-eight scans on eleven volunteers. The mentor and students acquired subcostal long axis views of the IVC and apical five chamber views using a high frequency linear ultrasound probe. Mean values from three measurements were obtained for IVC diameter and LVOT VTi. Minimum and maximum values were recorded for both variables across a full respiratory cycle. Echo images were saved and at least two images for each student were reviewed offline by an accredited echo-training supervisor. In all cases students were able to obtain adequate echo windows. There was good correlation between values recorded by the mentor and students for both IVC diameter (r = 0.90, p < 0.001) and LVOT VTi (r = 0.77, p < 0.001). Bland Altman analysis showed good correlation with minimal bias for VTi measurements. There was some increase in bias for IVC measurements below 1.2 cm. In summary, we found that these skills for assessing intravascular volume status could be acquired in a relatively short time by specialist nurses without previous experience, and that results were comparable to those produced by an experienced practitioner.