Learning profiles for noninvasive transcutaneous Doppler ultrasound.

OBJECTIVE: This study aimed to establish learning profiles for noninvasive transcutaneous Doppler ultrasound. MATERIALS AND METHODS: Four trainees attended a 2-h lecture, followed by a 15-min demonstration on a volunteer and a 30-min hands-on workshop in a small group setting. Then, they underwent hands-on practice on 50 participants without supervision. The skill acquisitions in terms of signal magnitude, signal quality, and measurement time of the trainees were evaluated through 50 assessments, and were compared with that of a trainer with extensive experience on the use of an ultrasonic cardiac output monitor acting as a 'gold standard'. The learning profile for each individual trainee was analyzed using the cumulative sum graphical method. RESULTS: Four trainees performed ultrasonic cardiac output monitor on 50 participants. All trainees attained proficiency after 18-36 assessments to achieve aortic signal magnitude and quality comparable with the trainer. It requires a minimum of nine assessments to obtain three aortic scans within 5 min with 95% success rates. Only half of the trainees achieved competence in pulmonary scans and the minimum number of assessments required was 36. A minimum of 22 assessments were required for three pulmonary scans within 10 min with 95% success rates. CONCLUSION: A substantial period of learning needs to be undertaken to achieve proficiency on the use of noninvasive transcutaneous Doppler ultrasound. Cumulative sum analysis is a useful tool for ongoing quality assessment during medical education and training in practical procedures on an individual basis.

Age-specific non-invasive transcutaneous Doppler ultrasound derived haemodynamic reference ranges in elderly Chinese adults.

BACKGROUND: Whilst there is a presumption in medicine that ageing adversely affects cardiovascular function, it is unknown if resting haemodynamics are compromised in the elderly, and if so, to what degree. This study was intended to answer several questions; whether age-related changes in haemodynamics occur; whether there was a difference between the haemodynamics of ageing subjects with and without mild chronic disease; whether there was a difference in haemodynamics as measured from either the aortic or the pulmonary valve; and to establish reference ranges for this population. METHODS: Chinese adults aged over 60 years were divided into three age bands of 61-70, 71-80 and over 80 years. The haemodynamic parameters were measured using a non-invasive Doppler ultrasound-based instrument, the Ultrasonic Cardiac Output Monitor (USCOM). RESULTS: One hundred and sixty-five subjects (48.5% males) were recruited. 78 (47.3%) had no known disease whilst 87 (52.7%) had mild chronic illness. A total of 21 individual haemodynamic parameters were measured or calculated for each subject. There were no significant differences in stroke volume (SV), cardiac output (CO), systemic vascular resistance (SVR) or in body surface area (BSA)-indexed parameters, SV index (SVI), cardiac index (CI) and SVR index (SVRI) across age groups, or in other indexed haemodynamic parameters. No significant differences in indexed haemodynamics were found between those subjects with and those without mild chronic disease. Small, statistically significant, but clinically insignificant, differences (< 5%) were found between the aortic and pulmonary valve measurements for SV, SVI and heart rate. CONCLUSIONS: Ageing does not have any significant effect on resting haemodynamics in the elderly population studied. Mild chronic disease does not adversely affect resting haemodynamics in this population. GENERAL SIGNIFICANCE: Reference ranges were established for 21 haemodynamic parameters, as measured by USCOM, for an elderly Chinese population but not for non-Chinese populations.

Influence of different positions on hemodynamics derived from noninvasive transcutaneous Doppler ultrasound.

A proper alignment of the ultrasound beam to the aortic or pulmonary outflow tracts is essential to acquire accurate signals. This study aimed to investigate the influence of different positions on the acquisition of Doppler signals using a noninvasive transcutaneous Doppler ultrasound. This was a prospective observational crossover study. Two operators performed hemodynamics measurements on each subject in supine, sitting, semirecumbent, passive leg raising (PLR) 20°, and PLR 60° positions using both aortic and pulmonary approaches. All Doppler flow profile images were assessed using the Fremantle and Prince of Wales Hospital criteria. Time required to obtain Doppler signals was recorded. A total of 60 subjects (50% males) aged 18-60 years old were investigated. In both sitting and semirecumbent positions, aortic stroke volume indexes (SVIs) and cardiac indexes (CIs) were significantly lower than those in the other three positions while the pulmonary CIs were comparable to that in the supine position. In the sitting position, the aortic signal qualities were lower and the time to obtain the pulmonary Doppler signals was prolonged. Instead, the signal quality and the time to obtain the Doppler signals in the semirecumbent position were similar to those in the other three positions using the pulmonary approach. PLR did not cause a significant increase in SVI regardless of the degree of leg elevation. These data show that it is feasible to perform the noninvasive transcutaneous Doppler ultrasound using the pulmonary approach in the semirecumbent position for patients unable to maintain the supine position. The aortic approach in the sitting and semirecumbent positions is not suitable as it is not sufficiently reliable.