Pulse Indicator Continuous Cardiac Output Research Articles

Evaluation of extravascular lung water index in critically ill patients based on lung ultrasound radiomics analysis combined with machine learning

To explore lung ultrasound radiomics features which related to extravascular lung water index (EVLWI), and to predict EVLWI in critically ill patients based on lung ultrasound radiomics combined with machine learning and validate its effectiveness. A retrospective case-control study was conducted. The lung ultrasound videos and pulse indicated continuous cardiac output (PiCCO) monitoring results of critically ill patients admitted to the department of critical care medicine of the First Affiliated Hospital of Guangxi Medical University from November 2021 to October 2022 were collected, and randomly divided into training set and validation set at 8:2. The corresponding images from lung ultrasound videos were obtained to extract radiomics features. The EVLWI measured by PiCCO was regarded as the "gold standard", and the radiomics features of training set was filtered through statistical analysis and LASSO algorithm. Eight machine learning models were trained using filtered radiomics features including random forest (RF), extreme gradient boost (XGBoost), decision tree (DT), Naive Bayes (NB), multi-layer perceptron (MLP), K-nearest neighbor (KNN), support vector machine (SVM), and Logistic regression (LR). Receiver operator characteristic curve (ROC curve) was plotted to evaluate the predictive performance of models on EVLWI in the validation set. A total of 151 samples from 30 patients were enrolled (including 906 lung ultrasound videos and 151 PiCCO monitoring results), 120 in the training set, and 31 in the validation set. There were no statistically significant differences in main baseline data including gender, age, body mass index (BMI), mean arterial pressure (MAP), central venous pressure (CVP), heart rate (HR), cardiac index (CI), cardiac function index (CFI), stroke volume index (SVI), global end diastolic volume index (GEDVI), systemic vascular resistance index (SVRI), pulmonary vascular permeability index (PVPI) and EVLWI. The overall EVLWI range in 151 PiCCO monitoring results was 3.7-25.6 mL/kg. Layered analysis showed that both datasets had EVLWI in the 7-15 mL/kg interval, and there was no statistically significant difference in EVLWI distribution. Two radiomics features were selected by using LASSO algorithm, namely grayscale non-uniformity (weight was -0.006 464) and complexity (weight was -0.167 583), and they were used for modeling. ROC curve analysis showed that the MLP model had better predictive performance. The area under the ROC curve (AUC) of the prediction validation set EVLWI was higher than that of RF, XGBoost, DT, KNN, LR, SVM, NB models (0.682 vs. 0.658, 0.657, 0.614, 0.608, 0.596, 0.557, 0.472). The gray level non-uniformity and complexity of lung ultrasound were the most correlated radiomics features with EVLWI monitored by PiCCO. The MLP model based on gray level non-uniformity and complexity of lung ultrasound can be used for semi-quantitative prediction of EVLWI in critically ill patients.

Utilizing Spontaneous Ventilation Modes in Patients Underwent Corrective Surgery for Right Ventricular Outflow Tract Obstructive Congenital Heart Disease: A Crossover Study

Background: This study aimed to determine whether the hemodynamics of patients with right ventricle outflow tract obstructive congenital heart disease (RVOTO-CHD) improve after corrective surgery by changing the ventilation mode. Methods: Patients with RVOTO-CHD who underwent corrective surgery were enrolled in this study. Echocardiography and advanced hemodynamic monitoring were performed using the pulse indicator continuous cardiac output (PiCCO) technology in the pressure-regulated volume control (PRVC) mode, followed with switching to the pressure support ventilation (PSV) mode and neurally adjusted ventilatory assist (NAVA) mode in random order. Results: Overall, 31 patients were enrolled in this study from April 2021 to October 2021. Notably, changing the ventilation mode from PRVC to a spontaneous mode (PSV or NAVA) led to better cardiac function outcomes, including right ventricular cardiac index (PRVC: 3.19 ± 1.07 L/min/m2 vs. PSV: 3.45 ± 1.32 L/min/m2 vs. NAVA: 3.82 ± 1.03 L/min/m2, p < 0.05) and right ventricle contractility (tricuspid annular peak systolic velocity) (PRVC: 6.58 ± 1.40 cm/s vs. PSV: 7.03 ± 1.33 cm/s vs. NAVA: 7.94 ± 1.50 cm/s, p < 0.05), as detected via echocardiography. Moreover, in the NAVA mode, PiCCO-derived cardiac index (PRVC: 2.92 ± 0.54 L/min/m2 vs. PSV: 3.04 ± 0.56 L/min/m2 vs. NAVA: 3.20 ± 0.62 L/min/m2, p < 0.05), stroke volume index (PRVC: 20.38 ± 3.97 mL/m2 vs. PSV: 21.23 ± 4.33 mL/m2 vs. NAVA: 22.00 ± 4.33 mL/m2, p < 0.05), and global end diastolic index (PRVC: 295.74 ± 78.39 mL/m2 vs. PSV: 307.26 ± 91.18 mL/m2 vs. NAVA: 323.74 ± 102.87 mL/m2, p < 0.05) improved, whereas extravascular lung water index significantly reduced (PRVC: 16.42 ± 7.90 mL/kg vs. PSV: 15.42 ± 5.50 mL/kg vs. NAVA: 14.4 ± 4.19 mL/kg, p < 0.05). Furthermore, peak inspiratory pressure, mean airway pressure, driving pressure, and compliance of the respiratory system improved in the NAVA mode. No deaths were reported in this study. Conclusions: We found that utilizing spontaneous ventilator modes, especially the NAVA mode, after corrective surgery in patients with RVOTO-CHD may improve their right heart hemodynamics and respiratory mechanics. However, further randomized controlled trials are required to verify the advantages of spontaneous ventilation modes in such patients. Clinical Trial Registration: NCT04825054.

Case report: Successful outcome of a young patient with rhabdomyolysis and shock caused by diquat poisoning.

The widespread use of diquat as a substitute for paraquat has led to an increase in poisoning deaths. A successful case of diquat poisoning complicated with rhabdomyolysis and shock was lacking. A 13-year-old previously healthy girl ingested 40 ml of diquat solution in a suicide attempt. The concentration of diquat in serum was 436.2 ug/L at 10 h after poisoning. The clinical course was characterized by progressive multi-organ dysfunction, particularly rhabdomyolysis and shock. The main treatments included intensive hemoperfusion combined with continuous renal replacement therapy (CRRT), drainage, and activated carbon adsorption. Meanwhile, accurate dilatation under the model of pulse indicator continuous cardiac output (PICCO) was essential for the successful treatment of shock. The serum concentration of diquat declined to 20 ug/L after 96 h of treatments. The patient was discharged from the hospital after 3 weeks of treatment without obvious symptoms. So far, this was the first successful case of diquat poisoning complicated with rhabdomyolysis and shock, which would enrich the experience of diquat poisoning treatment.

The relationship between left ventricular artery coupling and left ventricular work and their predictive value on prognosis in septic shock

Objective: To explore the relationship between left ventricular artery coupling and left ventricular work in patients with septic shock, and further clarified their predictive value for the prognosis of septic shock. Methods: In total, 56 patients with septic shock admitted in the Department of Critical Care Medicine of Peking Union Medical College Hospital were retrospectively enrolled between January 2016 and July 2021. The hemodynamic indexes and clinical data monitored by pulse indicator continuous cardiac output (PICCO) at different time points were collected. To reveal alterations of arterial elastance index (EaI), end-systolic elastance index (EesI), EaI/EesI, stroke work (SW), total cardiac function (PVA), and left ventricular ejection efficiency (LVEf) in patients with septic shock at different time points. The patients were divided into the death group (n=20) and survival group (n=36) according to the outcome of the ICU. The relationship between left ventricular work and left ventricular arterial coupling and its prognostic value were statistically analyzed. Results: A total of 56 patients were enrolled, 32 males and 24 females, aged (61±15) years. There was a significantly difference in EaI/EesI and LVEf between survivors and non-survivors with septic shock at 6 h (P<0.05). Further analysis showed that the correlation between EaI/EesI and LVEf was most evident at 6 h after intervention. EaI/EesI was negatively correlated with SW (rs=-0.500, P<0.001), and highly negative with LVEf (rs=-0.959, P<0.001). Both univariate logistic regression and multivariate regression analysis showed that EaI/EesI (adjusted OR=42.783, 95%CI: 2.725-671.819, P=0.008) and LVEf (adjusted OR=2.293, 95%CI:1.222-4.301, P=0.010) were risk factors for ICU prognosis of patients with septic shock. The receiver operating characteristic (ROC) curve analysis showed that EaI/EesI [area under the curve (AUC)=0.742±0.083, P=0.004; cut-off value 6.10, sensitivity 88.9%, specificity 65.0%] and LVEf (AUC=0.733±0.084, P=0.006; cut-off value 0.24, sensitivity 88.8%, specificity 60.0%) were both effective indicators for predicting the prognosis of patients with septic shock in the ICU. Moreover, EaI/EesI had a better prognosis value than LVEf (ΔAUC=0.120, Z=6.528, P=0.036). Conclusion: It's indicated that EaI/EesI was significantly correlated with SW and LVEf after 6 h of septic shock intervention; EaI/EesI and LVEf are risk factors and effective predictors of ICU prognosis in patients with septic shock. The predictive efficacy of EaI/EesI is greater than LVEF.

The role of pulse indicator continuous cardiac output (PiCCO) and critical care ultrasound in volume status assessment during fluid resuscitation for and prognosis of septic shock patients.

To investigate whether pulse index continuous cardiac output (PiCCO) and critical care ultrasound are highly consistent in volume status assessment during fluid resuscitation for septic shock patients and analyze their influence on the prognosis of septic shock. Eighty septic shock patients treated by Huizhou Central People's Hospital during December 2018 and December 2020 were included and divided into a study group and a control group by the presence of volume responsiveness, with each group having 40 patients. The control group was subject to PiCCO-guided fluid resuscitation therapy, while the study group was given fluid resuscitation therapy guided by critical care ultrasound. Cardiac output, cardiac function, and catheter-related infection (CRI) were documented for intergroup comparison to confirm whether these two techniques were consistent with each other regarding their effects on resuscitation for and prognosis of septic shock patients. Mechanical ventilation duration (MVD) and intensive care unit (ICU) length of stay (LoS) were significantly shorter in the study group when compared with the control group, and the differences were statistically significant (p<0.05, respectively). In terms of blood pressure parameters, the two groups did not differ greatly in diastolic blood pressure (DBP), mean arterial pressure (MAP), systolic blood pressure (SBP), and central venous pressure (CVP) before resuscitation (p>0.05, respectively); at 6h(six hour) after resuscitation, DBP, MAP, SBP, and CVP were substantially increased in both groups as compared with the pre-resuscitation levels (all p<0.05), but the differences between the two groups lacked statistical significance (all p>0.05). Comparing urine volume and degrees of positive fluid balance at 6 h and 12 h after resuscitation, drastic increases in urine volume and positive fluid balance were observed in both groups at 12 h as compared with at 6 h (all p<0.05); nevertheless, the two groups showed no statistically significant difference in urine volume and positive fluid balance at 6 h or 12 h (p>0.05, respectively). With regards to prognosis, there was no statistically significant difference between the two groups in the number of cases of continuous renal replacement therapy (CRRT), dosage of vasoactive agents and 28-d mortality rate (all p>0.05). However, the incidence of CRI was markedly lower in the study group (0/40) as compared with the control group (5/40), and the difference was statistically significant (p<0.05). Both PiCCO and critical care ultrasound can help achieve favorable outcomes from resuscitation for septic shock patients. Compared with PiCCO, critical care ultrasound monitoring appears to be more effective in preventing CRI and reducing MVD and ICU LoS, thereby easing patients' medical burden.

Clinical value of pulse pressure/central venous pressure ratio in low cardiac output syndrome after cardiac surgery

To explore the relationship between the pulse pressure/central venous pressure (PP/CVP) ratio and the cardiac output (CO) of patients after cardiac surgery from the basic principles of hemodynamics, and to further evaluate the predictive value of PP/CVP ratio in patients with secondary low cardiac output syndrome (LCOS) after cardiac surgery. A retrospective study was conducted, and patients who received pulse indicator continuous cardiac output (PiCCO) monitoring were enrolled at the department of critical care medicine of Peking Union Medical College Hospital from January 1, 2016, to September 1, 2021. Patients were divided into two groups: the LCOS group [cardiac index (CI) < 33.34 mL×s-1×m-2, 25 cases] and the non-LCOS group (CI ≥ 33.34 mL×s-1×m-2, 125 cases) according to the CI at 6 hours after surgery. The general clinical data and hemodynamic parameters were collected. Correlations between PP/CVP ratio and PiCCO monitoring indicators were performed with Pearson or Spearman correlation test. Receiver operator characteristic curve (ROC curve) analysis was carried out to evaluate the predictive value of the parameters in patients with LCOS after cardiac surgery. A total of 150 patients with PiCCO monitoring after cardiac surgery were included. There were no differences in baseline characteristics between the two groups, while PP in the LCOS group was lower than that in the non-LCOS group [mmHg (1 mmHg ≈ 0.133 kPa): 40 (37, 44) vs. 55 (46, 64)], CVP was higher than that in the non-LCOS group [mmHg: 12 (11, 14) vs. 10 (8, 12)], and PP/CVP ratio in the LCOS group was lower than that in the non-LCOS group [3.3 (2.9, 3.7) vs. 5.5 (4.6, 6.8)], with significant differences (all P < 0.05). Correlation analysis results showed that PP/CVP ratio was positively correlated with CI, CO, and stroke volume index (SVI), respectively (rs = 0.660, 0.592, 0.600, all P < 0.001). CI was negatively correlated with PP (rs = 0.509, P < 0.001) and positively correlated with CVP (rs = -0.297, P < 0.001). ROC curve analysis revealed that compared with PP, CVP, SVI and cardiac function index (CFI), PP/CVP ratio was the best predictor of LCOS after cardiac surgery [area under the ROC curve (AUC) was 0.94±0.02, P < 0.001], when the optimum cut-off value was 4.41, the sensitivity was 80.00%, and the specificity was 96.00%. PP/CVP ratio was moderately positively correlated with CO after cardiac surgery, and PP/CVP ratio could be used as a prognostic predictor for LCOS after cardiac surgery.

Effect of Pulse Indicator Continuous Cardiac Output Monitoring on Septic Shock Patients: A Meta-Analysis.

Background Septic shock (SS) is the most common severe syndrome in the Intensive Care Unit (ICU). Enhancing the monitoring of hemodynamic indexes in SS patients carries huge clinical implications for reducing patient mortality. Recently, pulse indicator continuous cardiac output (PICCO) has been widely used in clinical practice, but its advantages than central venous pressure (CVP) in guiding the treatment of SS patients remains to be refined. Therefore, this study is aimed at assessing the clinical effects of PICCO in the treatment of patients with SS. Methods The authors systematically searched several databases (PubMed, EMBASE, Cochrane Library, and China National Knowledge) between January 2001 and February 2021. When searching for relevant articles, the authors combined the following phrases describing the monitoring group (“pulse indicator continuous cardiac output,” “central venous pressure”) with the disease of interest as well as management (“SS,” “sepsis”). The outcomes were independently assessed by two reviewers who scored the articles for methodological quality using the Cochrane Collaboration's “risk of bias” tool. Forest plots, as well as sensitivity and bias analyses, were carried out for the included articles. The primary outcome measures were length of ICU stay, duration of mechanical ventilation, 28-day mortality, and fluid resuscitation volume. Results Ten studies comprising 350 cases monitored with PICCO and 373 cases monitored with traditional CVP were eventually identified. PICCO-monitored patients were observed to be significantly associated with shorter ICU stay than CVP-monitored patients (MD: −3.04, 95% CI: −4.74 to −1.34, P = 0.0005), shorter time of mechanical ventilation (MD: −1.84, 95% CI: −2.80 to −0.87, P = 0.0002), and lower 28-day mortality (RR: 0.67, 95% CI: 0.48 to 0.94, P = 0.02). The two groups showed no significant difference in subgroup analysis for fluid resuscitation volumes (P > 0.05). Conclusion PICCO monitoring technique can significantly improve the prognosis of SS patients, shorten the time of mechanical ventilation and ICU stay, and reduce the 28-day mortality, which has positive guiding significance for patients with SS. Given the limitations of the quantity and quality of included studies, further research is warranted to verify the conclusions.

Effects of different crystalloid resuscitation on renal function in septic shock rabbits under the guidance of pulse indicator continuous cardiac output

To study the effect of different crystalloid resuscitation on renal function in septic shock rabbits, and to provide a theoretical basis for the choice of crystalloid for clinical fluid resuscitation. Thirty-six healthy male New Zealand white rabbits were divided into six groups by random number table: control group, model group, and four crystalloid groups including normal saline (NS) group, lactate Ringer solution (LR) group, acetate Ringer solution (AR) group, and sodium potassium magnesium calcium glucose injection (SPMCG) group, with 6 rabbits in each group. Rabbits were infused with Escherichia coli lipopolysaccharide (LPS) 500 μg/kg via the marginal ear vein (infused at a constant speed within 20 minutes), and then continued to infuse in an increase of 300 μg/kg every 10 minutes, the maximum dose was 2 mg/kg, until the mean arterial pressure (MAP) dropped to 60% of the basal value, the septic shock model was considered to be successfully reproduced. The rabbits in the control group were not injected with LPS, and other operations were the same as in the model group. Different crystalloid groups were given crystal solution immediately after modeling for resuscitation (predetermined fluid volume 60 mL/kg, transfusion within 3 hours). The volume stress test was performed every hour to guide the fluid volume, and the stroke volume index increase rate (ΔSVI) < 15% was the end point of resuscitation. The control group and the model group were given NS 4 mL×kg-1×h-1 to maintain the physiological requirement. All groups were given tracheotomy and mechanical ventilation, and the hemodynamic changes were monitored by pulse-indicated continuous cardiac output (PiCCO). The dynamic changes of hemodynamic indexes, arterial blood gas analysis, electrolytes, blood glucose and renal function biomarkers were monitored before modeling, immediately after modeling and 3, 6, and 12 hours after resuscitation. (1) Hemodynamic indicators: after modeling, the MAP in the model group and the four fluid resuscitation groups decreased significantly, the cardiac index (CI) increased, and the systemic vascular resistance index (SVRI), global end-diastolic volumn index (GEDVI) decreased. After different crystalloid resuscitation at different time points, MAP, SVRI, and GEDVI increased in the four crystalloid groups. (2) Arterial blood gas analysis, electrolytes, blood glucose: blood lactic acid (Lac) in the model group and the four fluid resuscitation groups increased after model success. After fluid resuscitation, the Lac of each crystalloid group began to decrease and reached to the lowest at 12 hours. Compared with the LR, AR and SPMCG groups, the pH value decreased in the NS group at 6 hours and 12 hours of fluid resuscitation (6 hours: 7.29±0.00 vs. 7.40±0.02, 7.35±0.02, 7.37±0.02; 12 hours: 7.27±0.02 vs. 7.38±0.02, 7.39±0.02, 7.35±0.01; all P < 0.05). After fluid resuscitation, blood Cl- levels at 3, 6, and 12 hours in the NS group were significantly higher than those in the LR, AR and SPMCG groups (mmol/L: 113.4±0.6 vs. 101.4±3.6, 108.0±1.1, 106.0±0.8 at 3 hours; 115.1±2.0 vs. 101.1±2.7, 109.0±2.2, 105.3±0.6 at 6 hours; 116.9±0.1 vs. 104.2±4.4, 107.6±1.7, 108.7±0.6 at 12 hours; all P < 0.05). There was no significant difference in blood glucose at each time point among the four crystalloid groups. (3) Biomarkers of renal function: blood and urine neutrophil gelatinase associated lipocalin (NGAL) and cystatin C (Cys C) were significantly increased in the model group and four fluid resuscitation groups. After fluid resuscitation, blood, urine NGAL and Cys C decreased. There was no significant difference in blood, urine NGAL and Cys C at all the time points among the different fluid resuscitation groups. In the rabbit model of septic shock induced by Escherichia coli LPS, hyperchloremia and acidosis occurred after NS resucitation, but did not occur during the recovery of LR, AR and SPMCG. There was no difference in the effects of different crystalloid resuscitation on renal function in septic shock rabbits.

Clinical value of point of care ultrasound on cardiac output and volume responsiveness in patients with septic shock

To assess the value of point of care ultrasound on cardiac output (CO) and volume responsiveness in patients with septic shock. Twenty-four mechanical ventilation patients with septic shock who needed pulse-indicated continuous cardiac output (PiCCO) monitoring in the department of critical care medicine of Zhengzhou University People's Hospital, Henan Provincial People's Hospital from November 25, 2020 to April 30, 2021 were selected as the subjects, the patient's basic information and laboratory test results were recorded. PiCCO was used as standard to monitor CO and stroke volume variability (SVV) at 0, 2, 6, 12, 24 and 48 hours. At the same time, point of care transthoracic echocardiography (TTE) was used to measure velocity time integral (VTI) and inferior vena cava diameter (dIVC), the CO, VTI variation rate (ΔVTI) and dIVC variation rate (ΔdIVC) were calculated. Then, using the value monitored by PiCCO as the standard, the consistency and correlation analysis were carried out between point of care ultrasound with PiCCO. Twenty-two out of 24 patients obtained satisfactory ultrasound Doppler images, the heart rate (HR), mean arterial pressure (MAP) and body temperature of the enrolled patients were consistent with the pathophysiological characteristics of septic shock. With the extension of treatment time, HR and CO both gradually decreased, and MAP gradually increased, reaching a peak or trough at 48 hours after admission. The difference were statistically significant compared with the time of admission [HR (bpm): 90.36±15.35 vs. 116.82±19.82, MAP (mmHg, 1 mmHg = 0.133 kPa): 87.82±11.06 vs. 58.82±9.85, CO (L/min): 4.80±0.56 vs. 6.78±1.31, all P < 0.05]. The CO obtained by PiCCO and point of care ultrasound had good agreement [5.36 (4.78, 6.33) L/min and 5.21 (4.88, 6.35) L/min, respectively], the average difference value at each time point was (-0.02±0.69) L/min, the 95% agreement limit range was -1.35-1.34, and there was a high degree of correlation (rs = 0.800, P < 0.001); The SVV by PiCCO and the ΔdIVC by point of care ultrasound were in good agreement [18.00% (14.00%, 24.00%) and 21.00% (14.00%, 25.75%), respectively], the average difference value at the time point was (-3.16±6.89)%, the 95% agreement limit range was -16.89-10.54, and there was a moderate correlation (rs = 0.702, P < 0.001); The SVV by PiCCO and the ΔVTI by point of care ultrasound were in good agreement [18.00% (14.00%, 24.00%) and 16.00% (11.25%, 20.75%), respectively], the average difference value at each time point was (13.03±14.75)%, and the 95% agreement limit range was 1.72-27.78, and there was a high correlation (rs = 0.918, P < 0.001). Point of care ultrasound can accurately assess CO and volume responsiveness of patients with septic shock, and the ΔVTI is better than the ΔdIVC in assessing volume responsiveness.

Predictive value of carotid ultrasound in combination with passive leg raising on fluid responsiveness in critically ill patients

To investigate the value of monitor carotid velocity time integral (VTI) and corrected flow time (FTc) by bedside ultrasound before and after passive leg raising (PLR) in predicting fluid responsiveness in critically ill patients. A prospective observational study was conducted. Fifty patients with critical illness admitted to the First People's Hospital of Fuyang Hangzhou from January 2020 to March 2021 were enrolled. The clinical data including the gender, age, body mass index (BMI), acute physiology and chronic health evaluation II (APACHE II) score, and the duration of mechanical ventilation were recorded. The changes of carotid VTI and FTc were measured by bedside ultrasound, and the values of heart rate, mean arterial pressure (MAP), central venous pressure (CVP), stroke volume index (SVI), and intrathoracic blood volume index (ITBVI) were measured by pulse indicated continuous cardiac output (PiCCO) monitor before and after PLR in all patients. According to the changes of SVI before and after PLR, the patients were divided into fluid responsiveness positive group with the change rate of SVI ≥ 15% and fluid responsiveness negative group with the change rate of SVI < 15%. The differences in the values of VTI, FTc, CVP, and ITBVI obtained before and after PLR (ΔVTI, ΔFTc, ΔCVP and ΔITBVI) were calculated and then compared between the two groups. The predictive values of these indicators on fluid responsiveness in critically ill patients were analyzed by receiver operator characteristic curve (ROC curve), and their relationship with the difference in SVI (ΔSVI) obtained before and after PLR was evaluated by Pearson correlation analysis. Fifty patients were all enrolled in this study, in which 27 patients were fluid response and 23 patients were fluid nonresponse. Basic clinical data were not different between the two groups. The values of ΔVTI, ΔFTc, ΔCVP, and ΔITBVI in fluid response were all significantly higher than those in fluid nonresponse [ΔVTI (cm): 2.07±1.16 vs. 0.67±0.86, ΔFTc (ms): 4.00±6.10 vs. 0.01±2.26, ΔCVP (cmH2O, 1 cmH2O = 0.098 kPa): 1.67±1.14 vs. 1.00±1.17, ΔITBVI (mL/m2): 98±69 vs. 48±70, all P < 0.05]. ROC curve analysis showed that ΔVTI, ΔFTc, ΔCVP and ΔITBVI were all positive for predicting fluid responsiveness, their area under ROC curve (AUC) and 95% confidence interval (95%CI) were 0.870 (0.769-0.972), 0.694 (0.547-0.841), 0.684 (0.535-0.832) and 0.709 (0.564-0.855), respectively. When using ΔVTI 0.92 cm, ΔFTc 1.45 ms, ΔCVP 1.50 cmH2O and ΔITBVI 44.50 mL/m2 as the threshold values, the sensitivities were 96.3%, 63.0%, 44.4% and 81.5%, and the specificities were 65.2%, 78.3%, 82.6% and 56.5%, respectively, in which the predictive value of ΔVTI was the largest. Pearson correlation analysis indicated that ΔVTI, ΔFTc, ΔCVP, and ΔITBVI were positively associated with ΔSVI (r values were 0.971, 0.334, 0.440, 0.650, P values were 0.000, 0.018, 0.001, 0.000, respectively). Carotid ΔVTI and ΔFTc monitored by bedside ultrasound before and after PLR could be as effective as conventional indicators in predicting fluid responsiveness in critically ill patients, and the predictive value of ΔVTI was better than others.

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

To evaluate the prognostic value of transthoracic lung ultrasound comet-tail and extravascular lung water index (EVLWI) in septic patients. 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. 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. 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.

Evaluation of extravascular lung water in patients with acute respiratory distress syndrome by syndecan-1 combined with lung ultrasonography

To investigate the value of plasma syndecan-1 (SDC-1) combined with lung ultrasonography in evaluating the degree of extravascular lung water in patients with acute respiratory distress syndrome (ARDS). From July 2018 to July 2019, 50 patients with ARDS admitted to the department of intensive care unit of Wuxi People's Hospital Affiliated to Nanjing Medical University were enrolled. After admission, pulse indicator continuous cardiac output (PiCCO) catheter was established for all patients. PiCCO indexes, including extravascular lung water index (EVLWI) and pulmonary vascular permeability index (PVPI) were monitored by one doctor. Another doctor performed lung ultrasound examination, and calculated the sum of the number of B-lines under 10 ultrasound sections of upper blue point, lower blue point, diaphragm point, Plaps point and rear blue point of both lungs. Then the level of plasma SDC-1 was detected by enzyme linked immunosorbent assay (ELISA). Pearson correlation method was used to analyze the correlation between the number of ultrasonic B-lines, plasma SDC-1 level and EVLWI and PVPI. Taking 10 mL/kg EVLWI as the boundary value, the degree of pulmonary edema in patients with ARDS was divided into mild pulmonary edema and severe pulmonary edema. The receiver operator characteristic curve (ROC curve) was drawn, and the number of B-lines, SDC-1 and the predictive value of the combination of the above two indicators on the severity of pulmonary edema in patients with ARDS were analyzed. The cardiac index (CI) and central venous pressure (CVP) of 50 patients with ARDS were (46.84±6.00) mL×s-1×m-2 and (8.12±1.80) mmHg (1 mmHg = 0.133 kPa), cardiogenic pulmonary edema was excluded. In 50 patients with ARDS, EVLWI was (10.82±2.92) mL/kg, PVPI was 3.02±0.69, the number of ultrasound B-lines was 40.90±13.05, and plasma SDC-1 was (568.25±118.14) μg/L. Pearson correlation analysis showed that the number of ultrasound B-lines in patients with ARDS was significantly positively correlated with EVLWI and PVPI (r1 = 0.802, r2 = 0.799, both P < 0.01). Plasma SDC-1 was also positively correlated with EVLWI and PVPI (r1 = 0.732, r2 = 0.576, both P < 0.01). ROC curve analysis showed that the number of B-lines and SDC-1 had good predictive value for the severity of pulmonary edema in patients with ARDS. The area under ROC curve (AUC) and 95% confidence interval (95%CI) were 0.891 (0.803-0.979) and 0.875 (0.772-0.978), respectively. When the cut-off of B-lines was 40.50, the sensitivity and specificity were 82.1% and 86.4%, respectively. When the cut-off of SDC-1 was 559.37 μg/L, the sensitivity and specificity were 85.7% and 81.8%, respectively. Combining the number of B-lines with SDC-1 could further improve the predictive value of pulmonary water in patients with ARDS. The AUC (95%CI) was 0.958 (0.890-1.000), and the sensitivity and specificity were 92.9% and 91.8%, respectively. The level of plasma SDC-1 and the number of pulmonary ultrasonic B-lines have a good correlation with the degree of extravascular lung water in patients with ARDS. The combined application of the two noninvasive indexes can be used to evaluate the degree of extravascular lung water in patients with ARDS.

Extravascular Lung Water and Intrathoracic Blood Volume Index Are Associated With Liver Function in Brain Dead Donors for Organ Transplant.

Hemodynamic measurements during organ transplant procedures are essential. In this observational study, we measured clinical and hemodynamic parameters in 11 patients with advanced pulse indicator continuous cardiac output monitoring. Normally distributed clinical data were calculated as means ± standard deviation; hemodynamic, metabolic, and respiratory parameters related to liver and renal function were compared by linear regression analysis using Pearson correlation. Compared with the normal range, systemic vascular resistance was high (2278.02 ± 719.6 dyne·s/cm²/m²) and intrathoracic blood volume was low (787.37 ± 224.01 mL/m²) in our patient group. C-reactive protein and interleukin 6 levels were 96.26 ± 68.10 mg/mL and 246.24 ± 355.74 mmol/L, respectively. Liver and renal function parameters were in normal ranges. Extravascular lung water was correlated with total, conjugated, and unconjugated bilirubin and albumin (r = 0.342/P = .005; r = 0.338/ P = .005; r = 0.394/P = .001, and r = 0.358/P = .003) but not with aspartate aminotransferase, alanine aminotransferase, blood urea nitrogen, and serum creatinine. Intrathoracic blood volume index was correlated with total bilirubin, unconjugated bilirubin, and albumin (r = 0.324/P = .007; r = 0.394/P = .001, and r = 0.296/P = .015) but not with conjugated bilirubin, aspartate aminotransferase, alanine aminotransferase, blood urea nitrogen, and serum creatinine. Lactate was not correlated with total bilirubin, unconjugated bilirubin, albumin, and serum creatinine, but base excess was correlated with total bilirubin, unconjugated bilirubin, alanine aminotransferase, and albumin. PO₂ and Pco₂ were not correlated with liver function, although PO₂ was correlated with albumin. No correlations were shown between intrathoracic blood volume index, extravascular lung water, and liver function, but metabolic parameters, including base excess and lactate, were correlated with liver function. Pulse indicator continuous cardiac output monitoring may be a useful method to assess organ function and tissue perfusion in organ transplant.

The fluid management and hemodynamic characteristics of PiCCO employed on young children with severe hand, foot, and mouth disease\u2014a retrospective study

BackgroundHand, foot, and mouth disease (HFMD) is an acute infectious disease caused by human enterovirus 71 (EV71), coxsackievirus, or echovirus, which is particularly common in preschool children. Severe HFMD is prone to cause pulmonary edema before progressing to respiratory and circulatory failure; thus hemodynamic monitoring and fluid management are important to the treatment process.MethodsWe did a review of young patients who had been successfully treated in our department for severe HFMD, which had been caused by EV71. A total of 20 patients met the inclusion criteria. Eight cases were monitored by the pulse indicator continuous cardiac output (PiCCO) technique, and fluid management was administered according to its parameters. With regard to the treatment with PiCCO monitoring, patients were divided into two groups: the PiCCO group (8 patients) and the control group (12 patients). The groups were then compared comprehensively to evaluate whether PiCCO monitoring could improve patients’ clinical outcomes.ResultsAfter analysis, the findings informed that although PiCCO failed to shorten the length of ICU stay, reduce the days of vasoactive drug usage, or lower the number of cases which required mechanical ventilation, PiCCO did reduce the incidence of fluid overload (p = 0.085) and shorten the days of mechanical ventilation (p = 0.028). After effective treatment, PiCCO monitoring indicated that the cardiac index (CI) increased gradually(p < 0.0001), in contrast to their pulse (P, p < 0.0001), the extra vascular lung water index (EVLWI, p < 0.0001), the global end diastolic volume index (GEDVI, p = 0.0043), and the systemic vascular resistance index (SVRI, p < 0.0001), all of which decreased gradually.ConclusionOur study discovered that PiCCO hemodynamic monitoring in young children with severe HFMD has some potential benefits, such as reducing fluid overload and the duration of mechanical ventilation. However, whether it can ameliorate the severity of the disease, reduce mortality, or prevent multiple organ dysfunction remain to be further investigated.

Assessment of extravascular lung water by measuring the number of pulmonary ultrasound B-lines before and after CBP in patients with MODS.

To determine whether the change in the number of pulmonary ultrasound B-line can accurately assess the extravascular lung water (EVLW) before and after continuous bedside blood purification (CBP) in patients with multiple organ dysfunction syndrome (MODS).Seventy-six patients with MODS who underwent CBP were examined within 24 hours before and after CBP using pulmonary ultrasound to detect the number of ultrasound B-line or using pulse indicator continuous cardiac output method to examine extravascular lung water, blood oxygenation index, and B-type natriuretic peptide (BNP) content. The correlation of the change in the number of B lines before and after CBP treatment with the negative balance of 24 hours liquid, the change of oxygenation index, and BNP content were analyzed.In the 76 patients, CBP treatment significantly decreased EVLW, the number of B-line, and BNP (P < .05 for all), while it significantly increased the oxygenation index (P < .05). Correlation analysis showed that the decrease in B-line number after CBP treatment was positively correlated with the 24 hours negative lung fluid balance, decrease of EVLW, oxygenation index improvement, and decreased BNP content. The change in the numbers of pulmonary ultrasound B-line can accurately assess the change of EVLW before and after CBP treatment and reflect the efficiency of ventilation in the lungs and the risk of heart failure.Thus, it can replace pulse indicator continuous cardiac output as an indicator for evaluating EVLW in patients with MODS treated with CBP.

Effect of VTILVOT variation rate on the assessment of fluid responsiveness in septic shock patients.

This study aimed to assess the predictive value of velocity time integral (VTI) of the left ventricular outflow tract (LVOT) on volume expansion test (VET) as an indicator of volume responsiveness in septic shock patients. Septic shock patients undergoing mechanical ventilation were recruited. The hemodynamic parameters before and after VE were monitored by pulse indicated continuous cardiac output (PiCCO) and echocardiography. Heart rate, cardiac index (CI), mean arterial pressure (MAP), central venous pressure, stroke volume variation (SVV), CI and variation of pulse pressure (PPV), and the changes in cardiac parameters (Dheart rate, Dmean arterial pressure, Dcentral venous pressure, DSVV, DCI, and DPPV) were determined. The relationships of hemodynamic parameters and their changes with DVTI were further evaluated with Pearson relation analysis. The value of these parameters in fluid responsiveness prediction was evaluated by using the receiver operating characteristic (ROC) curve analysis. Results showed that 44 VETs were performed in 44 septic shock patients with responsiveness in 24 patients and non-responsiveness in 20. The CI increased by ≥ 15% in responsive patients, but by<15% in non-responsive patients after VET. There were significant differences in the SVV and PPV after VET between responsive and non-responsive groups. DSVV, DPPV, and DCI were positively related to DVTI. The area under ROC curve (AUC) for SVV in fluid responsiveness prediction was 0.80, and the sensitivity and specificity of SVV were 66.5% and 95%, respectively, when the cut-off value was 24.8%. The AUC for PPV in fluid responsiveness prediction was 0.843, and the sensitivity and specificity of PPV were 83.3% and 75%, respectively, when the cut-off value was 25.8%. The AUC for DVTILVOT in fluid responsiveness prediction was 0.956, and the sensitivity and specificity were 87.5% and 95%, respectively, when the cut-off value was 15.9%. In conclusion, DVTILVOT is effective to predict fluid responsiveness after VET in mechanical ventilation patients with septic shock. It may serve as a new, noninvasive and functional hemodynamic parameter with the same accuracy to SVV.

The value of growth differentiation factor-15 and extravascular lung water index in severity grading of acute respiratory distress syndrome patients and their prognosis prediction

To investigate the value of growth differentiation factor-15 (GDF-15) and extravascular lung water index (EVLWI) in severity grading and prognosis prediction of patients with acute respiratory distress syndrome (ARDS). Patients with ARDS aged 18-75 years admitted to the department of respiratory intensive care unit (RICU) of Zhengzhou Central Hospital Affiliated to Zhengzhou University from January 2019 to February 2020 were enrolled. All patients were treated with conventional therapies such as mechanical ventilation, anti-infection, stabilization of water, electrolytes and acid-base environment, blood purification and nutritional support according to their conditions. Besides, the pulse-indicated continuous cardiac output (PiCCO) was performed after admission to the department, and EVLWI before treatment and at 24, 48 and 72 hours of treatment were recorded. Serum GDF-15 level was measured by enzyme linked immunosorbent assay (ELISA) during the same period. Patients were classified as mild, moderate, and severe degree according to the 2012 Berlin Definition of ARDS, and EVLWI and GDF-15 levels in patients with different disease levels before and after treatment were compared. In addition, the length of intensive care unit (ICU) stay, ICU mortality, and 28-day mortality of patients with different GDF-15 or EVLWI levels were analyzed comparatively, with the GDF-15 3 458 ng/L and EVLWI 15 mL/kg as the cut point. A total of 82 patients with ARDS were enrolled, including 22 patients with mild ARDS, 28 patients with moderate ARDS, and 32 patients with severe ARDS. The GDF-15 and EVLWI levels in patients with moderate and severe ARDS at each time point before and after treatment were higher than those in patients with mild ARDS. Both GDF-15 and EVLWI levels in patients with severe ARDS were higher than those in the patients with moderate ARDS. The differences were statistically significant at all the time points except for the difference of GDF-15 levels at 24 hours after treatment (ng/L: 3 900.41±546.43 vs. 3 695.66±604.73, P > 0.05). [GDF-15 (ng/L): 3 786.11±441.45 vs. 3 106.83±605.09 before treatment, 3 895.48±558.96 vs. 3 333.29±559.66 at 48 hours, 3 397.33±539.56 vs. 3 047.53±499.57 at 72 hours; EVLWI (mL/kg): 19.06±1.91 vs. 14.31±1.50 before treatment, 18.56±2.23 vs. 13.26±1.69 at 24 hours, 17.23±1.76 vs. 12.45±1.36 at 48 hours, 15.47±1.81 vs. 11.13±2.19 at 72 hours, all P < 0.05]. According to the cut-off value, there were 23 patients with GDF-15 ≥ 3 458 ng/L and GDF-15 < 3 458 ng/L respectively and there were 23 patients with EVLWI ≥ 15 mL/kg and EVLWI < 15 mL/kg respectively. The length of ICU stay and 28-day mortality in patients with high GDF-15 were significantly higher than those in patients with low GDF-15 [length of ICU stay (days): 21.22±2.69 vs. 15.37±3.14, 28-day mortality: 56.5% vs. 21.7%, both P < 0.05]. The length of ICU stay and 28-day mortality in patients with high EVLWI were also significantly higher than those in patients with low EVLWI [length of ICU stay (days): 18.45±2.61 vs. 14.98±2.75, 28-day mortality: 47.8% vs. 17.4%, both P < 0.05]. To some extent, GDF-15 and EVLWI levels reflect the severity of patients with ARDS, and high GDF-15 and EVLWI levels are significantly associated with poor prognosis in patients with ARDS.

Effect of different fluid resuscitation strategies on renal function in patients with septic shock induced acute kidney injury

To compare the therapeutic effect of fluid resuscitation strategy guided by pulse-indicated continuous cardiac output (PiCCO) monitoring and early goal-directed therapy (EGDT) on renal function of acute kidney injury (AKI) patients caused by septic shock. Septic shock patients with AKI admitted to the intensive care unit (ICU) of Tianjin Fifth Central Hospital and Teda International Cardiovascular Hospital from March 2017 to February 2020 were enrolled. All patients were given fluid resuscitation. Patients were divided into PiCCO-guided fluid resuscitation group [PiCCO group, intrathoracic blood volume index (ITBVI) was maintained between 850-1 000 mL/m2] and EGDT-guided fluid resuscitation group [EGDT group, central venous pressure (CVP) was maintained between 8-12 mmHg (1 mmHg = 0.133 kPa) or CVP ≤ 15 mmHg when patients received mechanical ventilation (MV)] according to both the patient's condition and the informed consent of the patient's family. The changes of heart rate (HR), mean arterial pressure (MAP), CVP, blood lactic acid (Lac), fluid balance, urine volume and serum creatinine (SCr) at 6, 24, and 48 hours after fluid resuscitation in the two groups were observed, and the renal replacement therapy (RRT), duration of MV, length of ICU stay and 28-day mortality between the two group were compared. (1) A total of 94 patients were enrolled, including 51 in the EGDT group and 43 in the PiCCO group. There was no significant difference in gender, age, acute physiology and chronic health evaluation II (APACHE II) score, sequential organ failure assessment (SOFA) score, procalcitonin (PCT), HR, MAP, CVP, Lac or SCr at ICU admission between the two groups. (2) The parameters of hemodynamics, fluid balance, urine volume and SCr were improved with the time of resuscitation in the two groups, and there was no significant difference in HR, MAP or Lac between the two groups. Compared with the EGDT group, the CVP decreased significantly at 24 hours and 48 hours after fluid resuscitation in the PiCCO group (mmHg: 9.1±0.9 vs. 12.0±1.3 at 24 hours, 8.0±1.0 vs. 10.2±1.3 at 48 hours), the fluid balance significantly decreased (mL: 2 929.8±936.3 vs. 3 898.4±923.5 at 24 hours, 3 143.5±1 325.4 vs. 4 843.8±1 326.7 at 48 hours), and the condition of urine volume and SCr were better in the PiCCO group [urine volume (mL×kg-1×h-1): 1.02±0.21 vs. 0.79±0.14 at 24 hours, 1.28±0.18 vs. 0.94±0.22 at 48 hours; SCr (μmol/L): 145.7±37.6 vs. 164.3±46.4 at 24 hours, 128.4±33.6 vs. 143.5±37.7 at 48 hours), with significant differences (all P < 0.05). (3) Compared with the EGDT group, the rate of RRT in the PiCCO group was lower [11.6% (5/43) vs. 17.6% (9/51)], the duration of MV and the length of ICU stay were shorter [duration of MV (days): 4.64±1.31 vs. 6.50±2.19, length of ICU stay (days): 10.35±3.50 vs. 14.50±5.78), with significant differences (all P < 0.05). There was no significant difference in the 28-day mortality between the PiCCO group and EGDT group [14.0% (6/43) vs. 15.7% (8/51), P > 0.05]. Fluid resuscitation strategy guided by PiCCO in septic shock patients with AKI can reduce the amount of fluid load, improve renal function, shorten the MV duration and length of ICU stay, and shows clinical significance.

Comparison of pulmonary circulation hemodynamics and respiratory mechanics induced by drowning with equal volume of freshwater and seawater in sheep: a randomized controlled study

To compare the effects of freshwater and seawater drowning on sheep's pulmonary circulation hemodynamics and respiratory mechanics. According to the random number table method, healthy crossbred sheep were divided into freshwater drowning group (n = 12) and seawater drowning group (n = 12). 30 mL/kg of freshwater or seawater was infused respectively through trachea for approximately 5 minutes. Before the drowning, immediately after drowning, and 30, 60, 120 minutes after drowning, the systemic circulation hemodynamic parameters [heart rate (HR), mean arterial pressure (MAP), cardiac output (CO)] were monitored by pulse indicator continuous cardiac output (PiCCO); the respiratory parameters were obtained through the ventilator, including tidal volume (VT), lung compliance (Cdyn), oxygenation index (PaO2/FiO2), peak airway pressure (Ppeak)]; PiCCO and the right heart floating catheter (Swan-Ganz catheter) was used to measure pulmonary hemodynamic parameters [pulmonary systolic pressure (PAS), pulmonary diastolic pressure (PAD), pulmonary artery wedge pressure (PAWP), and extravascular lung water (EVLW)]. The animals were sacrificed at the end of the experiment, and the amount of residual water in the respiratory tract was measured; the pathological changes in the lung tissue were observed by hematoxylin-eosin (HE) staining. (1) Systemic circulation hemodynamics: compared with the values before drowning, HR, MAP, and CO at the time of immediately after drowning in both freshwater and seawater were significantly increased and peaked. In addition, all indicators in the freshwater drowning group were significantly higher than those in the seawater drowning group [HR (bpm): 170.75±1.87 vs. 168.67±2.27, MAP (mmHg, 1 mmHg = 0.133 kPa): 172.92±1.62 vs. 159.42±3.18, CO (L/min): 13.27±0.71 vs. 10.33±0.73, all P < 0.05]. (2) Respiratory parameters: compared with values before drowning, PaO2/FiO2, VT, and Cdyn decreased immediately in both freshwater and seawater drowning groups, Ppeak was significantly increased; in addition, the values in the seawater drowning group were decreased or increased more significantly than freshwater drowning group [PaO2/FiO2 (mmHg): 37.83±1.99 vs. 60.42±5.23, VT (mL): 86.25±7.66 vs. 278.75±9.67, Cdyn (mL/cmH2O): 8.86±0.33 vs. 23.02±0.69, Ppeak (cmH2O, 1 cmH2O = 0.098 kPa): 42.17±2.69 vs. 17.67±1.15, all P < 0.01]. In addition, PaO2/FiO2 in the freshwater drowning group was gradually increased over time, while the seawater group continued to decline. (3) Pulmonary circulation hemodynamic parameters: PAS, PAD, PAWP at the time of immediately after drowning in both freshwater and seawater groups were significantly higher than before drowning; in addition, the freshwater drowning group was significantly higher than the seawater drowning group [PAS (mmHg): 34.58±2.87 vs. 26.75±1.66, PAD (mmHg): 27.25±1.22 vs. 16.75±0.87, PAWP (mmHg): 27.83±1.85 vs. 11.75±1.82, all P < 0.01]. Thereafter, PAS and PAD in the freshwater drowning group gradually decreased, while the parameters in the seawater drown group continued to increase. PAWP gradually decreased after freshwater or seawater drowning, and recovered to pre-drowning levels 120 minutes after drowning and 30 minutes after drowning, respectively. EVLW continued to increase after freshwater drowning, reaching a peak at 30 minutes, and then decreased, until 120 minutes after drowning was still significantly higher than that before drowning (mL/kg: 10.73±1.27 vs. 7.67±0.69, P < 0.01); EVLW could not be measured. (4) Residual water in the respiratory tract: residual water in the freshwater drowning group was significantly less than that in the seawater drowning group (mL: 164.33±25.21 vs. 557.33±45.23, P < 0.01). (5) HE staining: partial alveolar atrophied in the freshwater drowning group, some alveolar spaces were broken, alveolar spaces and alveolar cavity showed a little powdery substance deposition; it was noted that alveolar expanded in the seawater drowning group, alveolar spaces were broken and bleeding and edema were obvious in the interstitial space. The effect of seawater drowning on the respiratory mechanics and pulmonary circulation of animals is more obvious than that of freshwater drowned animals, and the amount of residual water in the respiratory tract is also significantly more than that of freshwater drowned animals.

Preliminary establishment of weaning prediction model

To establish a model that can predict weaning failure from ventilation through hemodynamic and fluid balance parameters. A retrospective analysis was conducted. The patients who underwent invasive mechanical ventilation for more than 24 hours and having spontaneous breathing test admitted to intensive care unit (ICU) of Tianjin Third Central Hospital from January 1st, 2017 to December 31st, 2018 were enrolled. The information was collected, which included the baseline data, hemodynamic parameters by pulse indicator continuous cardiac output (PiCCO) monitoring, B-type natriuretic peptide (BNP), urinary output, fluid balance in first 24 hours when patients admitted to ICU, and hemodynamic parameters by PiCCO monitoring, BNP, urinary output, fluid balance, diuretic usage, noradrenalin usage within 24 hours before weaning as well as usage of continuous renal replacement therapy (CRRT) during mechanical ventilation. According to weaning success or failure, the patients were divided into weaning success group and weaning failure group, and the statistical differences between the two groups were calculated. Variables with statistical significance within 24 hours before weaning were included in the multivariate Logistic regression analysis to establish weaning failure prediction model and find out the possible risk factors of weaning failure. A total of 159 patients were included in this study, which included 138 patients in the weaning success group and 21 patients in the weaning failure group. There were no statistical differences in all hemodynamic parameters by PiCCO monitoring, BNP, urinary output, fluid balance within 24 hours into ICU between two groups. There were statistical differences in BNP (χ2 = 9.262, P = 0.026), central venous pressure (CVP; χ2 = 7.948, P = 0.047), maximum rate of the increase in pressure (dPmx; χ2 = 10.486, P = 0.015), urinary output (χ2 = 8.921, P = 0.030), fluid balance (χ2 = 9.172, P = 0.027) within 24 hours before weaning between two groups. In addition, variable about cardiac index (CI; χ2 = 7.789, P = 0.051) was included into multivariate Logistic regression model to improve the prediction model and enhance the accuracy of model. Finally, variables included in the multivariate Logistic regression model were BNP, CVP, CI, dPmx, urinary output, fluid balance volume, and the accuracy of the weaning failure prediction model was 92.9%, the sensitivity was 100%, and the specificity was 76.8%. When the model was adjusted by variables of age and noradrenalin usage, the accuracy of model to predict failure of weaning was 94.2%, the sensitivity was 100%, the specificity was 81.2%. Weaning failure prediction model based on hemodynamic parameters by PiCCO monitoring and variables about liquid balance has high accuracy and can guide clinical weaning.