Xu Yd

[The value of N-terminal pro-B type natriuretic peptide in predicting the outcome of spontaneous breathing trials in elderly renal dysfunction patients].

OBJECTIVE To investigate the value of N-terminal pro-B type natriuretic peptide (NT-proBNP) in predicting the outcome of spontaneous breathing trial (SBT) in ventilated elderly renal dysfunction patients. METHODS The clinical data of patients who received mechanical ventilation in the Department of Critical Care Medicine of the First Affiliated Hospital of Guangzhou Medical University, Guangzhou Institute of Respiratory Disease from January 2011 to December 2014 were analyzed retrospectively. AU the patients conformed to the following criteria: age > 65 years, endogenous creatinine clearance rate (CCr) < 60 mL×min(-1)×1.73 m(-2), the duration of mechanical ventilation > 72 hours and undergone at least one SBT. The patients were assigned to a SBT success group and a SBT failure group according to the outcome of first SBT. The following factors were recorded: gender, age, the underlying disease [chronic obstructive pulmonary disease (COPD), heart failure (HF) and others], body mass index (BMI), serum pre-albumin (pre-ALB), and acute physiology and chronic health evaluation II (APACHE II) score, CCr and the concentration of the plasma NT-proBNP before SBT. Receiver operator characteristic curve (ROC) was plotted, and the predict value of NT-proBNP for the outcome of SBT in elder patients with kidney dysfunction was determined. RESULTS A total of 58 patients with complete data were enrolled, with 41 cases in SBT success group, and 17 in SBT failure group. There were no significant differences in gender [male/female (cases): 26/15 vs. 13/4, χ (2) = 0.930, P = 0.335], age (years: 70.2±7.4 vs. 74.6±10.1, t = 0.833, P = 0.339), the stratification of underlying diseases [COPD/HF/COPD+HF/others (cases): 15/9/13/4 vs. 7/3/5/2, χ (2) = 0.242, P = 0.971], BMI (kg/m(2): 25.2±11.3 vs. 27.4±6.43, t = 1.038, P = 0.221), pre-ALB (mg/L: 201.0±13.2 vs. 189.0±7.6, t = 0.688, P = 0.519), and APACHE II score (12.2±3.2 vs. 13.5±6.3, t = 1.482, P = 0.147) and CCr (mL×min(-1)×1.73 m(-2): 51.3±7.7 vs. 54.2±6.4, t = 0.711, P = 0.487) before SBT between SBT success group and SBT failure group. The concentration of plasma NT-proBNP in SBT failure group was significantly higher than that of the SBT success group (μg/L: 4.162±1.128 vs. 2.284±1.399, t = 4.905, P = 0.000). The area under ROC curve for plasma NT-proBNP in predicting successful SBT among elder patients with kidney dysfunction was 0.878, with 95% confidence interval (95%CI) 0.786 - 0.970. The cut-off method was used, and it was identified that the concentration of NT-proBNP < 3.350 μg/L as a predictor for successful SBT, with sensitivity of 82.4%, specificity of 87.8%, positive prediction value of 88.1% and negative predictive value of 76.5%. CONCLUSIONS The concentration of plasma NT-proBNP may increase in elderly kidney dysfunction patients undergoing ventilation, and NT-proBNP < 3.350 μg/L can serve as a good predictor for SBT success.

Effect of time elapsed on continuous pulse contour cardiac output measurement in septic shock patients

OBJECTIVE To evaluate the effect of time elapsed on continuous pulse contour cardiac output (PCCO) measurement in septic shock patients. METHODS Data during February 2011 to February 2013 from 25 septic shock patients equipped with a pulse indicator continuous cardiac output (PiCCO) device in Department of Critical Care Medicine of Guangzhou Medical University were retrospectively analyzed. PCCO was recorded immediately before transpulmonary thermodilution (COTPTD) calibration. After divided by ideal body surface area, cardiac index (CI) was calculated, and PCCI/CITPTD pairs were analyzed. Four subsets of CI pairs were defined according to intervals of time elapsed from the previous calibration [within the first hour (including 1 hour), between 1 and 8 hours (including 8 hours), between 8 and 16 hours (including 16 hours), and more than 16 hours]. Linear regression, the threshold value of concordance (as indicated by bias ± 2SD) and percentage error (2SD/the mean of CITPTD) were used to compare agreement between PCCI and CITPTD. RESULTS A total of 162 data pairs from 25 patients were analyzed. For all data pairs, PCCI correlated significantly with CITPTD (r² = 0.494, P<0.001), the bias±2SD was -(0.06 ± 1.41) L × min⁻¹ × m⁻² and the percentage error was 37%. Among the four time-interval subsets, the percentage error was <30% only in subset between 1 and 8 hours, and the percentage error in other subsets was over 30%. Linear regression analysis between ΔPCCI and ΔCITPTD showed a r² of 0.217 (P<0.001) for the whole 162 data pairs. A r² of 0.327 (P<0.001) and a r² of 0.303 (P<0.001) were calculated for the subset of between 1 and 8 hours and between 8 and 16 hours respectively. CONCLUSIONS Our study in septic shock patients suggests that the accuracy of PCCO will be decreased as the increase of the time interval for calibration. Transpulmonary thermodilution calibration should be performed again if hemodynamic changes or was inconsistent with the clinical presentation. It is suggested that re-calibration should be done within 8 hours.