Objectives: 1 To develop a training package for ultrasonic cardiac output monitor (USCOM) cardiac output assessments and determine the number of proctored studies necessary for skill acquisition. 2 To develop criteria for acceptance of cardiac output results obtained with the USCOM. 3 To evaluate the reliability of USCOM cardiac output assessments in the ED.
Methods: The authors developed an audiovisual training package. Four emergency physicians and one geriatrician subsequently underwent hands-on training, and skill acquisition was assessed at the fifth, 10th, 15th and 20th examinations. Six image-scoring criteria were developed to assess acoustic image quality. Upon completion of training a protocol was developed to optimize interassessor reliability. Two trained emergency physicians then performed blinded examinations on ED patients using the protocol and interassessor reliability was evaluated.
Results: During training average image score improved between the fifth and 20th assessed patient from 4.6 (95% CI 4.0-5.3) to 5.5 (95% CI 5.0-6.0, Pt-test=0.02) out of 6 and average intra-assessor cardiac output difference improved from 17% (95% CI 4-25) to 5% (95% CI 0-11, Pt-test=0.02). Analysis of 52 cardiac output assessments in 21 ED patients demonstrated excellent interassessor correlation (r=0.96, 95% CI 0.90-0.98, P<0.001). The average interassessor difference in cardiac output and index was 0.2 L/min (4%, 95% CI 3-6) and 0.1 L/min/m2 (4%, 95% CI 2-6), respectively.
Conclusion: Emergency physicians with no prior ultrasonographic experience can be trained to obtain reliable cardiac output estimations upon conscious ED patients with the USCOM over the course of 20 patient assessments.