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Background A simple measurement of central venous pressure (CVP)-mean by the digital monitor display has become increasingly popular. However, the agreement between CVP-mean and CVP-end (a standard method of CVP measurement by analyzing the waveform at end-expiration) is not well determined. This study was designed to identify the relationship between CVP-mean and CVP-end in critically ill patients and to introduce a new parameter of CVP amplitude (ΔCVP= CVPmax - CVPmin) during the respiratory period to identify the agreement/disagreement between CVP-mean and CVP-end.Methods In total, 291 patients were included in the study. CVP-mean and CVP-end were obtained simultaneously from each patient. CVP measurement difference (|CVP-mean - CVP-end|) was defined as the difference between CVP-mean and CVP-end. The ΔCVP was calculated as the difference between the peak (CVPmax) and the nadir value (CVPmin) during the respiratory cycle, which was automatically recorded on the monitor screen. Subjects with |CVP-mean - CVP-end|≥ 2 mmHg were divided into the inconsistent group, while subjects with |CVP-mean - CVP-end| < 2 mmHg were divided into the consistent group.Results ΔCVP was significantly higher in the inconsistent group [7.17(2.77) vs.5.24(2.18), P<0.001] than that in the consistent group. There was a significantly positive relationship between ΔCVP and |CVP-mean - CVP-end| (r=0.283, P <0.0001). Bland-Altman plot showed the bias was -0.61 mmHg with a wide 95% limit of agreement (-3.34, 2.10) of CVP-end and CVP-mean. The area under the receiver operating characteristic curves (AUC) of ΔCVP for predicting |CVP-mean - CVP-end| ≥ 2 mmHg was 0.709. With a high diagnostic specificity, using ΔCVP<3 to detect |CVP-mean - CVP-end| lower than 2mmHg (consistent measurement) resulted in a sensitivity of 22.37% and a specificity of 93.06%. Using ΔCVP>8 to detect |CVP-mean - CVP-end| >8 mmHg (inconsistent measurement) resulted in a sensitivity of 31.94% and a specificity of 91.32%.Conclusions CVP-end and CVP-mean have statistical discrepancies in specific clinical scenarios. ΔCVP during the respiratory period is related to the variation of the two CVP methods. A high ΔCVP indicates a poor agreement between these two methods, whereas a low ΔCVP indicates a good agreement between these two methods.
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Humans , Central Venous Pressure , Respiration , ROC CurveABSTRACT
Mechanical power of ventilation, currently defined as the energy delivered from the ventilator to the respiratory system over a period of time, has been recognized as a promising indicator to evaluate ventilator-induced lung injury and predict the prognosis of ventilated critically ill patients. Mechanical power can be accurately measured by the geometric method, while simplified equations allow an easy estimation of mechanical power at the bedside. There may exist a safety threshold of mechanical power above which lung injury is inevitable, and the assessment of mechanical power might be helpful to determine whether the extracorporeal respiratory support is needed in patients with acute respiratory distress syndrome. It should be noted that relatively low mechanical power does not exclude the possibility of lung injury. Lung size and inhomogeneity should also be taken into consideration. Problems regarding the safety limits of mechanical power and contribution of each component to lung injury have not been determined yet. Whether mechanical power-directed lung-protective ventilation strategy could improve clinical outcomes also needs further investigation. Therefore, this review discusses the algorithms, clinical relevance, optimization, and future directions of mechanical power in critically ill patients.
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BACKGROUND@#The peripheral perfusion index (PI), as a real-time bedside indicator of peripheral tissue perfusion, may be useful for determining mean arterial pressure (MAP) after early resuscitation of septic shock patients. The aim of this study was to explore the response of PI to norepinephrine (NE)-induced changes in MAP.@*METHODS@#Twenty septic shock patients with pulse-induced contour cardiac output catheter, who had usual MAP under NE infusion after early resuscitation, were enrolled in this prospective, open-label study. Three MAP levels (usual MAP -10 mmHg, usual MAP, and usual MAP +10 mmHg) were obtained by NE titration, and the corresponding global hemodynamic parameters and PI were recorded. The general linear model with repeated measures was used for analysis of variance of related parameters at three MAP levels.@*RESULTS@#With increasing NE infusion, significant changes were found in MAP (F = 502.46, P < 0.001) and central venous pressure (F = 27.45, P < 0.001) during NE titration. However, there was not a significant and consistent change in continuous cardiac output (CO) (F = 0.41, P = 0.720) and PI (F = 0.73, P = 0.482) at different MAP levels. Of the 20 patients enrolled, seven reached the maximum PI value at usual MAP -10 mmHg, three reached the maximum PI value at usual MAP, and ten reached the maximum PI value at usual MAP +10 mmHg. The change in PI was not significantly correlated with the change in CO (r = 0.260, P = 0.269) from usual MAP -10 mmHg to usual MAP. There was also no significant correlation between the change in PI and change in CO (r = 0.084, P = 0.726) from usual MAP to usual MAP +10 mmHg.@*CONCLUSIONS@#Differing MAP levels by NE infusion induced diverse PI responses in septic shock patients, and these PI responses may be independent of the change in CO. PI may have potential applications for MAP optimization based on changes in peripheral tissue perfusion.
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Limitation of consciousness level in intensive care unit (ICU) patients poses a great challenge to muscle strength assessment. Muscle ultrasound does not require patient cooperation, and can objectively measure significant changes in muscle cross-sectional area, thickness, echo intensity, and pennation angle to identify muscle atrophy early in the ICU. At the same time, muscle ultrasound technology is easy to be grasped by ICU doctors and nurses, and both show great reliability, which has certain significance for identifying patients at high risk of ICU-acquired weakness. In addition, ultrasound quantitative assessment of muscle has great value for predicting patient outcomes. Large-scale studies on the diagnostic value of ultrasound in ICU-acquired weakness are still lacking, and standardized ultrasound assessment scheme requires further discussion.
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Objective:@#Poor tissue perfusion/cellular hypoxia may persist despite restoration of the macrocirculation (Macro). This article reviewed the literatures of coherence between hemodynamics and tissue perfusion in circulatory shock.@*Data sources:@#We retrieved information from the PubMed database up to January 2018 using various search terms or/and their combinations, including resuscitation, circulatory shock, septic shock, tissue perfusion, hemodynamic coherence, and microcirculation (Micro).@*Study selection:@#The data from peer-reviewed journals printed in English on the relationships of tissue perfusion, shock, and resuscitation were included.@*Results:@#A binary (coherence/incoherence, coupled/uncoupled, or associated/disassociated) mode is used to describe resuscitation coherence. The phenomenon of resuscitation incoherence (RI) has gained great attention. However, the RI concept requires a more practical, systematic, and comprehensive framework for use in clinical practice. Moreover, we introduce a conceptual framework of RI to evaluate the interrelationship of the Macro, Micro, and cell. The RI is divided into four types (Type 1: Macro-Micro incoherence + impaired cell; Type 2: Macro-Micro incoherence + normal cell; Type 3: Micro-Cell incoherence + normal Micro; and Type 4: both Macro-Micro and Micro-cell incoherence). Furthermore, we propose the concept of dynamic circulation-perfusion coupling to evaluate the relationship of circulation and tissue perfusion during circulatory shock.@*Conclusions:@#The concept of RI and dynamic circulation-perfusion coupling should be considered in the management of circulatory shock. Moreover, these concepts require further studies in clinical practice.
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OBJECTIVE@#Poor tissue perfusion/cellular hypoxia may persist despite restoration of the macrocirculation (Macro). This article reviewed the literatures of coherence between hemodynamics and tissue perfusion in circulatory shock.@*DATA SOURCES@#We retrieved information from the PubMed database up to January 2018 using various search terms or/and their combinations, including resuscitation, circulatory shock, septic shock, tissue perfusion, hemodynamic coherence, and microcirculation (Micro).@*STUDY SELECTION@#The data from peer-reviewed journals printed in English on the relationships of tissue perfusion, shock, and resuscitation were included.@*RESULTS@#A binary (coherence/incoherence, coupled/uncoupled, or associated/disassociated) mode is used to describe resuscitation coherence. The phenomenon of resuscitation incoherence (RI) has gained great attention. However, the RI concept requires a more practical, systematic, and comprehensive framework for use in clinical practice. Moreover, we introduce a conceptual framework of RI to evaluate the interrelationship of the Macro, Micro, and cell. The RI is divided into four types (Type 1: Macro-Micro incoherence + impaired cell; Type 2: Macro-Micro incoherence + normal cell; Type 3: Micro-Cell incoherence + normal Micro; and Type 4: both Macro-Micro and Micro-cell incoherence). Furthermore, we propose the concept of dynamic circulation-perfusion coupling to evaluate the relationship of circulation and tissue perfusion during circulatory shock.@*CONCLUSIONS@#The concept of RI and dynamic circulation-perfusion coupling should be considered in the management of circulatory shock. Moreover, these concepts require further studies in clinical practice.
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Objective To investigate the influence of optimized mode for the hemodynamics short -term training course on the training effectiveness.Methods From 2016 to 2017,an optimized training mode was used in the hemodynam-ics 2-day training course in Peking Union Medical College Hospital,and the training effectiveness was evaluated.The optimized training mode included optimized course structure,opened-on-line answer questions,pre-training and post-training examination.Results A total of 808 clinical doctors participated in the hemodynamic training courses,and 627 participators finished both pre-training and post-training examinations.The percent of the pass of the examination was 44% at the baseline, and the percent of the pass of the examination was 88.2% after the training course.The post-training score was significantly higher than the pre-training score in the subgroup of 627 participators(pair-t-test, pre-training score 55.7±19.3 vs.post-training score 73.7±10.5,difference 18±21,P<0.001).Moreover,there was no relationship between pre-training score and post-training score.Conclusions The optimized mode of the hemody-namics short-term training course can improve the short-term training effectiveness.However,further studies are nee-ded to improve the application of hemodynamics in the clinical practice.
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<p><b>Background</b>Measurement of general microcirculation remains difficult in septic shock patients. The peripheral perfusion index (PI) and sublingual microcirculation monitoring are thought to be possible methods. This study was performed to determine whether assessing microcirculation by PI and a new parameter, proportion of perfusion vessel change rate (△PPV) from sublingual microcirculation monitoring, can be associated with patients' outcome.</p><p><b>Methods</b>A prospective observational study was carried out, including 74 patients with septic shock in a mixed intensive care unit. Systemic hemodynamic variables were obtained at T0 and 6 h after (T6). PI and sublingual microcirculation indicators were obtained using a bedside monitor and a sidestream dark-field device, respectively. The t-test, analysis of variance, Mann-Whitney U-test, Kruskal-Wallis test, receiver operating characteristic curve analysis with the Hanley-McNeil test, survival curves using the Kaplan-Meier method, and the log-rank (Mantel-Cox) test were used to statistical analysis.</p><p><b>Results</b>Systemic hemodynamics and microcirculation data were obtained and analyzed. Patients were divided into two groups based on whether the first 6 h lactate clearance (LC) was ≥20%; PI and △PPV were lower at T6 in the LC <20% group compared with LC ≥20% (PI: 1.52 [0.89, 1.98] vs. 0.79 [0.44, 1,81], Z = -2.514, P = 0.012; △PPV: 5.9 ± 15.2 vs. 17.9 ± 20.0, t = -2.914, P = 0.005). The cutoff values of PI and △PPV were 1.41% and 12.1%, respectively. The cutoff value of the combined indicators was 1.379 according to logistic regression. Area under the curve demonstrated 0.709 (P < 0.05), and the sensitivity and specificity of using combined indicators were 0.622 and 0.757, respectively. Based on the PI and △PPV cutoff, all the participants were divided into the following groups: (1) high PI and high △PPV group, (2) high PI and low △PPV group, (3) low PI and high △PPV group, and (4) low PI and low △PPV group. The highest Sequential Organ Failure Assessment score (14.5 ± 2.9) was in the low PI and low △PPV group (F = 13.7, P < 0.001). Post hoc tests showed significant differences in 28-day survival rates among these four groups (log rank [Mantel-Cox], 20.931; P < 0.05).</p><p><b>Conclusion</b>PI and △PPV in septic shock patients are related to 6 h LC, and combining these two parameters to assess microcirculation can predict organ dysfunction and 28-day mortality in patients with septic shock.</p>
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Aged , Female , Humans , Male , Middle Aged , Hemodynamics , Physiology , Intensive Care Units , Microcirculation , Physiology , Prognosis , Prospective Studies , ROC Curve , Sepsis , Shock, SepticABSTRACT
<p><b>BACKGROUND</b>Electrical impedance tomography (EIT) is a real-time bedside monitoring tool, which can reflect dynamic regional lung ventilation. The aim of the present study was to monitor regional gas distribution in patients with acute respiratory distress syndrome (ARDS) during positive-end-expiratory pressure (PEEP) titration using EIT.</p><p><b>METHODS</b>Eighteen ARDS patients under mechanical ventilation in Department of Critical Care Medicine of Peking Union Medical College Hospital from January to April in 2014 were included in this prospective observational study. After recruitment maneuvers (RMs), decremental PEEP titration was performed from 20 cmH 2 O to 5 cmH 2 O in steps of 3 cmH 2 O every 5-10 min. Regional over-distension and recruitment were monitored with EIT.</p><p><b>RESULTS</b>After RMs, patient with arterial blood oxygen partial pressure (PaO 2) + carbon dioxide partial pressure (PaCO 2 ) >400 mmHg with 100% of fractional inspired oxygen concentration were defined as RM responders. Thirteen ARDS patients was diagnosed as responders whose PaO 2 + PaCO 2 were higher than nonresponders (419 ± 44 mmHg vs. 170 ± 73 mmHg, P < 0.0001). In responders, PEEP mainly increased recruited pixels in dependent regions and over-distended pixels in nondependent regions. PEEP alleviated global inhomogeneity of tidal volume and end-expiratory lung volume. PEEP levels without significant alveolar derecruitment and over-distension were identified individually.</p><p><b>CONCLUSIONS</b>After RMs, PEEP titration significantly affected regional gas distribution in lung, which could be monitored with EIT. EIT has the potential to optimize PEEP titration.</p>