[Prognostic value of transthoracic lung ultrasound comet-tail and extravascular lung water index in septic patients].

OBJECTIVE: To evaluate the prognostic value of transthoracic lung ultrasound comet-tail and extravascular lung water index (EVLWI) in septic patients. METHODS: A prospective cohort study was conducted. Sixty septic patients admitted to department of intensive care unit (ICU) of Sichuan Provincial People's Hospital from November 2016 to October 2019 were enrolled. The EVLWI and pulmonary vascular permeability index (PVPI) were determined by pulse-indicated continuous cardiac output (PiCCO) system at 0, 24, 48 and 72 hours. At the same time, the numbers of comet tail signs in both lungs (parasternal, midclavicular, axillary to midaxillary) were collected by chest ultrasound. Moreover, arterial blood gas analysis, such as pH value, central venous-to-arterial carbon dioxide difference (Pcv-aCO2), central venous oxygen saturation (ScvO2), blood lactic acid (Lac), PaO2/FiO2 were measured. Pearson correlation analysis was performed between the number of comet-tail sign and EVLWI. Multivariate Logistic regression model was used to analyze the relationship between the number of comet-tail sign, EVLWI and prognosis. Receiver operator characteristic curve (ROC curve) was drawn to predict the prognosis. RESULTS: There were 43 males and 17 females in 60 septic patients. The average age was (64.3±15.5) years old (range: 31-83 years old). There were 35 cases with pulmonary infection, 10 cases with abdominal infection, 6 cases with urinary tract infection, 3 cases with skin and soft tissue infection, 3 cases with intestinal infection, 1 case with meningitis, 1 case with cellulitis and 1 case with multiple injury. Acute respiratory distress syndrome (ARDS) occurred with 8 patients; 40 patients (66.7%) survived and 20 patients (33.3%) died on day 28. Pearson correlation analysis showed that the number of comet-tail sign was positively correlated with EVLWI (r = 0.944, P < 0.001). There was significant difference in the number of comet-tail signs among sepsis patients with different primary infection sites (H = 17.714, P < 0.001). The number of comet-tail signs in sepsis patients with pulmonary infection [19 (13, 27)] was significantly higher than that with other infections. The number of comet-tail sign in patients with ARDS was significantly higher than that in patients without ARDS [27 (19, 30) vs. 15 (9, 24), H = 25.387, P < 0.001]. Multivariate Logistic regression analysis showed that EVLWI, the number of comet-tail signs and PVPI were independent risk factors for death in septic patients [odds ratio (OR) and 95% confidence interval (95%CI) were 10.772 (1.161-99.851), 2.360 (1.070-5.202), 2.042 (1.152-3.622), all P < 0.05]. The accuracy, sensitivity, specificity, positive predictive value, negative predictive value of Logistic regression model based on comet-tail sign and EVLWI were 90.0%, 90.0%, 90.0%, 81.8%, 94.7%, respectively, and area under curve (AUC) were 0.926±0.018, 95%CI was 0.912-0.975, P < 0.001. CONCLUSIONS: The transthoracic lung ultrasound comet-tail in septic patients is significantly correlated with EVLWI monitored by PiCCO. The transthoracic lung ultrasound comet-tail combined with EVLWI can better improve the sensitivity, specificity and accuracy of 28-day prognosis in septic patients.