Objective To investigate the predictive value of left ventricular diastolic function on mechanical ventilation weaning in patients with left ventricular ejection fraction (LVEF) > 0.50.Methods A retrospective case control study was conducted. Sixty-five patients with LVEF > 0.50 undergoing mechanical ventilation for more than 48 hours admitted to surgery intensive care unit (ICU) of China-Japan Friendship Hospital from June 2014 to December 2016 were enrolled. The clinical data and parameters of echocardiography before spontaneous breathing trial (SBT) were collected. The possible relationship between left ventricular diastolic function and the results of weaning was analyzed according to analysis of blood flow filling parameters of mitral valve orifice. According to the grading standard of left ventricular diastolic function, the patients were divided into normal, mild (level 1) and moderate to severe (level 2-3) groups, and the outcomes of weaning were compared among the groups. Then patients were also divided into two groups of weaning successfully and weaning failure, and the clinical data and left ventricular diastolic function parameters of patients were compared between the two groups. The predictive value of left ventricular diastolic function on results of weaning was evaluated with receiver operating characteristic curve (ROC).Results Sixty-five patients were enrolled and 28 patients (43.1%) failed weaning, 22 patients failed the first SBT and 6 required reintubation within 48 hours, 31 of the patients presented normal left ventricular diastolic function, 9 of patients presented mild diastolic dysfunction, and 25 of them presented moderate to severe diastolic dysfunction. So with the gradual increase of the severity of diastolic dysfunction, the rate of weaning failure was gradually increased, which was 16.1%, 44.6% and 76.0% respectively (χ2 = 20.240,P = 0.001). Patients who failed weaning presented evidence of increased left ventricular filling pressures at pre-SBT, by demonstrating decreased deceleration time of E (DTE, s: 180.4±5.1vs. 196.8±4.0,t = 2.567,P = 0.013), increased left ventricular mitral valve diastolic early and late filling velocity ratio (E/A: 1.47±0.08 vs. 1.14±0.05, t = 3.827,P = 0.000), increased lateral, septal and averaged left ventricular mitral valve diastolic early velocity and maximal velocity of mitral annulus in early diastolic velocity ratio (E/Em: 10.26±0.52 vs. 7.28±0.41,t = 4.535, P = 0.000; 10.08±0.58 vs. 8.16±0.40,t = 2.797,P = 0.007; 10.17±0.48比7.72±0.35,t = 4.231,P = 0.000), and the rapid shallow breathing index (RSBI) was also increased significantly (61.7±3.6 vs. 50.6±2.7,t = 2.507, P = 0.015). It was shown by ROC curve analysis that the basic left ventricular diastolic function at pre-SBT had the diagnostic performance in predicting the outcome of weaning from mechanical ventilation, especially E/A and lateral E/Em. Pre-SBT values of E/A greater than 1.2 and lateral E/Em greater than 7.9 predicted weaning failure with an area under the ROC curve (AUC), sensitivity, and specificity of 0.81±0.06 and 0.85±0.06, 82.6% and 91.3%, 81.4% and 80.7%, respectively, and the AUC was higher than RSBI (0.70±0.07). The AUC of combination of E/A > 1.2 and lateral E/Em > 7.9predicting weaning failure was 0.86±0.05 with a sensitivity of 78.3% and a specificity of 93.6%.Conclusions The results suggest that left ventricular diastolic dysfunction is significantly associated with weaning outcome in critical patients with LVEF > 0.50. The combination of E/A ratio greater than 1.2 and E/Em ratio greater than 7.9 may identify patients at high risk of weaning failure.

Objective:To explore the risk factors of intensive care unit-acquired weakness (ICU-AW) and the characteristics of Medical Research Council (MRC) score and electromyogram.Methods:A case control study was conducted. Patients with mechanical ventilation ≥ 7 days and MRC score admitted to department of respiratory and critical care medicine of China-Japan Friendship Hospital from September 2018 to January 2020 were enrolled, and they were divided into ICU-AW group (MRC score < 48) and non-ICU-AW group (MRC score ≥ 48) according to MRC score. The general situation, past medical history, related risk factors, MRC score, respiratory support mode, laboratory examination results, electromyogram examination results, ICU-AW related treatment, outcome and length of ICU stay were collected, and the differences between the two groups were compared. The risk factors of ICU-AW were analyzed by binary multivariate Logistic regression, and the characteristics of MRC score and electromyogram were analyzed.Results:A total of 60 patients were enrolled in the analysis, including 17 patients in ICU-AW group and 43 patients in non-ICU-AW group. Univariate analysis showed that there were significant differences in acute physiology and chronic health evaluation Ⅱ (APACHEⅡ) score, sequential organ failure assessment (SOFA) score, brain natriuretic peptide (BNP), blood urea nitrogen (BUN) on the first day of ICU admission and the ratio of invasive mechanical ventilation between ICU-AW group and non-ICU-AW group [APACHEⅡ score: 21 (18, 25) vs. 18 (15, 22), SOFA score: 7 (5, 12) vs. 5 (3, 8), BNP (ng/L): 364.3 (210.1, 551.2) vs. 160.1 (66.8, 357.8), BUN (mmol/L): 9.9 (6.2, 17.0) vs. 6.0 (4.8, 9.8), invasive mechanical ventilation ratio: 88.2% vs. 46.5%, all P < 0.05]. Binary multivariate Logistic regression analysis showed no independent risk factor for ICU-AW. The average MRC score of 17 ICU-AW patients was 33±11. The limb weakness was symmetrical, and the proximal limb weakness was the main manifestation. Electromyography examination showed that the results of nerve conduction examination in ICU-AW patients mainly revealed that the amplitude of compound muscle action potential (CMAP) and sensory nerve action potentials (SNAP) were decreased, and the conduction velocity was slowed down; needle electromyography showed increased area of motor unit potential (MUP), prolonged time limit and a large number of spontaneous potentials. Prognosis evaluation showed that compared with non-ICU-AW group, patients in ICU-AW group underwent more tracheotomy (70.6% vs. 11.6%), longer length of ICU stay (days: 57±52 vs. 16±8), and more rehabilitation treatment (58.8% vs. 14.0%), and the differences were statistically significant (all P < 0.01). Conclusions:The occurrence of ICU-AW may be related to high APACHEⅡ score and SOFA score, high levels of BNP and BUN on the first day of ICU admission and the proportion of invasive mechanical ventilation, but the above factors are not independent risk factors for ICU-AW. The MRC score of ICU-AW patients was characterized by symmetrical limb weakness, mainly proximal limb weakness; in electromyography examination, the nerve conduction examination results mainly showed that CMAP and SNAP amplitude were decreased, and conduction velocity was slowed down; needle electromyography examination showed increased MUP area, prolonged duration and a large number of spontaneous potentials.