ObjectiveTo investigate whether inferior vena cava (IVC) ultrasound can improve the success rate of weaning in patients with respiratory failure by comparing the difference of success rate between ultrasound-guided weaning mode and spontaneous breathing test (SBT) weaning mode.MethodsFrom November 2017 to May 2018, 31 respiratory failure patients underwent mechanical ventilation in intensive care unit were randomly divided into an ultrasonic guidance group (16 cases) and a control group (15 cases). All of them were offline after meeting the offline indications. The routine group was assessed by SBT for offline procedures. The diameter and variation rate of inferior vena cava were measured at SBT. IVC diameter >2.0 cm and variation rate < 50% were given intravenous diuretics. After the IVC diameter reached the standard again, the catheter was taken off the machine after passing SBT. The patients of both groups were considered as successfully weaned when they were able to tolerate at least 48 consecutive hours of spontaneous breathing. The following data were recorded at weaning, ie. Acute Physiological and Chronic Health Evaluation Ⅱ (APACHEⅡ) score, arterial blood gas analysis, plasma albumin, serum electrolyte sodium, potassium, 7-day and 14-day weaning success rate.ResultsThere were no significant differences in APACHEⅡ score, plasma albumin level, arterial oxygen partial pressure, carbon dioxide partial pressure, pH, blood sodium level or blood potassium level between the two groups at the beginning of weaning (all P>0.05), and the 2-day weaning success rate was higher in the ultrasound group than that in the control group (95% vs. 73%, P=0.039); the 7-day weaning success rate was higher in the ultrasound group than that in the control group (87% vs. 66%, P=0.043). No significant difference was found in the 14-day weaning success rate (68% in the ultrasound group vs. 53% in the control group, P=0.446).ConclusionUltrasound can improve the success rate of weaning in patients with respiratory failure.