Clinical value of point of care ultrasound on cardiac output and volume responsiveness in patients with septic shock

Abstract

To assess the value of point of care ultrasound on cardiac output (CO) and volume responsiveness in patients with septic shock. Twenty-four mechanical ventilation patients with septic shock who needed pulse-indicated continuous cardiac output (PiCCO) monitoring in the department of critical care medicine of Zhengzhou University People's Hospital, Henan Provincial People's Hospital from November 25, 2020 to April 30, 2021 were selected as the subjects, the patient's basic information and laboratory test results were recorded. PiCCO was used as standard to monitor CO and stroke volume variability (SVV) at 0, 2, 6, 12, 24 and 48 hours. At the same time, point of care transthoracic echocardiography (TTE) was used to measure velocity time integral (VTI) and inferior vena cava diameter (dIVC), the CO, VTI variation rate (ΔVTI) and dIVC variation rate (ΔdIVC) were calculated. Then, using the value monitored by PiCCO as the standard, the consistency and correlation analysis were carried out between point of care ultrasound with PiCCO. Twenty-two out of 24 patients obtained satisfactory ultrasound Doppler images, the heart rate (HR), mean arterial pressure (MAP) and body temperature of the enrolled patients were consistent with the pathophysiological characteristics of septic shock. With the extension of treatment time, HR and CO both gradually decreased, and MAP gradually increased, reaching a peak or trough at 48 hours after admission. The difference were statistically significant compared with the time of admission [HR (bpm): 90.36±15.35 vs. 116.82±19.82, MAP (mmHg, 1 mmHg = 0.133 kPa): 87.82±11.06 vs. 58.82±9.85, CO (L/min): 4.80±0.56 vs. 6.78±1.31, all P < 0.05]. The CO obtained by PiCCO and point of care ultrasound had good agreement [5.36 (4.78, 6.33) L/min and 5.21 (4.88, 6.35) L/min, respectively], the average difference value at each time point was (-0.02±0.69) L/min, the 95% agreement limit range was -1.35-1.34, and there was a high degree of correlation (rs = 0.800, P < 0.001); The SVV by PiCCO and the ΔdIVC by point of care ultrasound were in good agreement [18.00% (14.00%, 24.00%) and 21.00% (14.00%, 25.75%), respectively], the average difference value at the time point was (-3.16±6.89)%, the 95% agreement limit range was -16.89-10.54, and there was a moderate correlation (rs = 0.702, P < 0.001); The SVV by PiCCO and the ΔVTI by point of care ultrasound were in good agreement [18.00% (14.00%, 24.00%) and 16.00% (11.25%, 20.75%), respectively], the average difference value at each time point was (13.03±14.75)%, and the 95% agreement limit range was 1.72-27.78, and there was a high correlation (rs = 0.918, P < 0.001). Point of care ultrasound can accurately assess CO and volume responsiveness of patients with septic shock, and the ΔVTI is better than the ΔdIVC in assessing volume responsiveness.