In a recent prospective observational study comprising 125 patients, which of the following is the most likely finding regarding the use of an ultrasonography protocol in a general intensive care unit (ICU)?
(A) Ultrasound findings modified the admission diagnosis in approximately 25 percent of patients.
(B) Ultrasound findings led to changes in medical therapy in approximately 50 percent of patients.
(C) The median time to perform a complete “head to toe” ultrasound examination exceeded 45 minutes.
(D) Ultrasound findings showed low agreement between two attending physicians.
The limitations of physical examination and other diagnostic modalities in ICU patients are well described. Bedside ultrasonography is safe, rapid, portable and repeatable. The authors of a recent study investigated the “ICU-sound” protocol, a critical care ultrasound protocol, to see if alterations in diagnosis and therapy in general ICU patients occurred. The physicians who undertook this study were experienced in ultrasonography. They had completed a continuing education course that included 150 scans of body sections and also had received one year of tutored instruction. The complete ultrasound protocol includes scans of the 1) optic nerve (for depressed consciousness); 2) chest; 3) heart; 4) abdomen; and 5) venous system (for thrombi), performed within 12 hours of ICU admission. An example of altering the diagnosis is a chest ultrasound that clarifies a generic diagnosis of acute respiratory insufficiency to pleural effusion, pneumonia, or pneumothorax.
A total of 125 consecutive patients who were expected to be in the ICU more than 48 hours (excluding postoperative and overdose patients) were examined. The ultrasound protocol modified the admitting diagnosis in 25.6 percent of patients and confirmed the diagnosis in 58.4 percent of patients. In fact, these examinations showed abnormalities on ultrasound in the great majority of patients (86 percent), with most of the new ultrasound findings in patients with septic shock or acute cardiac decline. In half of the patients, ultrasound findings were confirmed by a more definitive exam, which included the use of computed tomography, magnetic resonance imaging, and transesophageal echocardiography (TEE). Three cases of anterior pneumothorax not detected by anterior-posterior chest X-ray were discovered by ultrasound. Patient-related factors precluded the performance of a complete exam in nine patients, and ultrasonography led to the addition of invasive procedures in 27 patients (21.6 percent).
Time to complete this rapid global ultrasound assessment ranged from 17 to 54 minutes, with a median time of 19.5 minutes. Interrater agreement of ultrasound findings between attending physicians was generally good as evidenced by a κ coefficient of 0.69 (range, 0.52–0.86). The Cohen’s κ is a statistical measure of interrater agreement wherein the higher the coefficient, the greater the reliability; below 0.4 would be considered poor or low agreement.
Changes in medical management due to incidental findings on ultrasound are not new. The authors of a previous study found that 31 percent of (88 of 283) consecutive patients undergoing cardiac surgery had new findings on TEE, altering surgical management in 25 percent of these patients, including the use or non-use of cardiopulmonary bypass. The ultrasound discoveries in the current study similarly led to significant changes in medical therapy in 22 of 125 patients (17.6 percent). Whether these findings ultimately altered patient outcome is unknown.
• Manno E, Navarra M, Faccio L, et al. Deep impact of ultrasound in the intensive care unit: the “ICU-sound” protocol. Anesthesiology. 2012;117(4):801-809.
• Minhaj M, Patel K, Muzic D, et al. The effect of routine intraoperative transesophageal echocardiography on surgical management. J Cardiothorac Vasc Anesth. 2007; 21(6):800-804.