Resistance Index of the Superior Mesenteric Artery: Correlation With Lactate Concentration and Kinetics Prediction After Cardiac Surgery.

Huaiwu He,Na Cui,Xiaoting Wang,Yuankai Zhou,Yun Long,Xiang Zhou,Dawei Liu

doi:10.3389/fmed.2021.762376

Abstract

Objective: This study aimed to measure blood flow changes in the superior mesenteric artery (SMA), using Doppler ultrasound, in post-cardiac surgery patients, to evaluate the correlation between the SMA resistance index (SMA-RI) and lactate concentrations.Methods: The patients' basic hemodynamics, blood gas parameters and lactate concentration were collected at admission. Simultaneously, the SMA blood flow parameters were collected using Doppler ultrasound with the patients in the supine position. The lactate concentrations were measured again at 2, 6, and 12-h time points after the first test. The length of intensive care unit stays and prognoses continued to be monitored.Results: A total of 67 patients were included. The SMA-RI correlated with the admission (r = 0.3117, P = 0.0102), 2-h (r = 0.5091, P < 0.0001), 6-h (r = 0.5061, P < 0.0001), and 12-h (r = 0.2483, P = 0.0428) lactate concentrations. The SMA-RI could predict the 2-h 10% [area under the curve (AUC) = 0.8294, P < 0.0001] and 6-h 40% lactate kinetics (AUC = 0.7708, P = 0.0012). The cut-off value was 0.83. When the SMA-RI was <0.83, the specificity and sensitivity were 86.38 and 75.56%, respectively for the prediction of the 2-h >10% lactate kinetics, and 64.71 and 75.00%, respectively, for the prediction of the 6-h >40% lactate kinetics. The lactate concentrations at admission, 2 and 6-h points were higher in the high-RI group (RI ≥ 0.83) and the intensive care unit stays were significantly longer than in the low-RI group (P = 0.0005).Conclusions: The increase in SMA-RI was associated with higher lactate concentrations and worse lactate kinetics in post-cardiac surgery patients. This may be related to intestinal hypoperfusion. The SMA-RI may be one of the indicators that should be monitored to guide resuscitation in these patients.

Highlights

Hyperlactatemia often occurs in patients following cardiac surgery and the mechanisms are often various which include the tissue hypoperfusion, hypothermia, undergoing cardiopulmonary bypass [1, 2]
Patients aged 18–80 years who were admitted to the intensive care unit (ICU) after cardiac surgery were included in this study
We found a good correlation between the SMA-resistance index (RI) and lactate concentrations at admission and the 2, 6, and 12-h time points

Summary

Introduction

Hyperlactatemia often occurs in patients following cardiac surgery and the mechanisms are often various which include the tissue hypoperfusion, hypothermia, undergoing cardiopulmonary bypass [1, 2]. The persistence of hyperlactatemia is associated with a worse prognosis [2,3,4,5]. In those patients with tissue hypoperfusion, the longer duration of hyperlactatemia always means the longer hypoxia of tissue and greater damage to the organs. There is a lack of indicator that can predict it This can lead to the delay of treatment, prolonged hyperlactatemia, and a worsening of the prognosis. We hope to find the indicator of organ hypoperfusion to initiate our treatment in advance to reduce the duration of hypoperfusion, so as to improve the prognosis of patients after cardiac surgery with tissue hypoperfusion

Methods

Results

Conclusion