Association between elevated central venous pressure and outcomes in critically ill patients

Exploring the optimal range of central venous pressure in sepsis and septic shock patients: A retrospective study in 208 hospitals

BACKGROUND

The aim of this study was to investigate the optimal CVP range in sepsis and septic shock patients admitted to intensive care unit.

METHODS

We performed a retrospective study with adult sepsis patients with CVP records based on the eICU Collaborative Research Database. Multivariable logistic regression was performed to explore the associations between CVP level and hospital mortality. Non-linear correlations and optimal CVP range were explored using restricted cubic splines (RCS).

RESULTS

A total of 5302 sepsis patients were included in this study. Patients in 4-8 mmHg group owned the lowest odds ratio for raw hospital mortality (19.7%). The logistic regression analyses revealed that hospital death risk increased significantly when mean CVP level exceeds 12 mmHg compared to 4-8 mmHg level. U-shaped association of CVP with hospital mortality was revealed by RCS model in septic shock patients and the optimal range was 5.6-12 mmHg. While, there was a J-shaped trend for non-septic shock patients. For non-septic shock patients, patients had an increased risk of hospital death only if CVP exceeded 11 mmHg.

CONCLUSIONS

We observed U-shaped association between mean CVP level and hospital mortality in septic shock patients and J-shaped association in non-septic shock patients. This may imply that patients with different severity of sepsis have different CVP requirements. We need to monitor and manage CVP according to the circulatory status of the sepsis patient.

Exploring congestion endotypes and their distinct clinical outcomes among ICU patients: A post-hoc analysis

BACKGROUND

In the intensive care unit (ICU) patients, fluid overload and congestion are associated with worse outcomes. Because of the heterogeneity of ICU patients, we hypothesized that there may exist different endotypes of congestion. The aim of this study was to identify endotypes of congestion and their association with outcomes.

METHODS

We conducted an unsupervised hierarchical clustering analysis on 145 patients admitted to ICU to identify endotypes. We measured several parameters related to clinical context, volume status, filling pressure, and venous congestion. These parameters included NT-proBNP, central venous pressure (CVP), the mitral E/e' ratio, the systolic/diastolic ratio of hepatic veins' flow velocity, the mean diameter of the inferior vena cava (IVC) and its variations, stroke volume changes following passive leg raising, the portal vein pulsatility index, and the venous renal impedance index.

RESULTS

Three distinct endotypes were identified: (1) "hemodynamic congestion" endotype (n = 75) with moderate alterations of ventricular function, increased CVP and left filling pressure values, and moderate fluid overload; (2) "volume overload congestion" endotype (n = 50); with normal cardiac function and filling pressure despite high positive fluid balance (fluid overload); (3) "systemic congestion" endotype (n = 20) with severe alterations of left and right ventricular functions, increased CVP and left ventricular filling pressure values. These endotypes vary significantly in ICU admission reasons, acute kidney injury rates, mortality, and length of ICU/hospital stay.

CONCLUSIONS

Our analysis revealed three unique congestion endotypes in ICU patients, each with distinct pathophysiological features and outcomes. These endotypes are identifiable through key ultrasonographic characteristics at the bedside.

CLINICAL TRIAL GOV

NCT04680728.

Monitoring the venous circulation: novel techniques and applications

PURPOSE OF REVIEW

Venous pressure is an often-unrecognized cause of patient morbidity. However, bedside assessment of PV is challenging. We review the clinical significance of venous pressure measurement, existing techniques, and introduce the Venous Excess Ultrasound (VExUS) Score as a novel approach using doppler ultrasound to assess venous pressure.

RECENT FINDINGS

Studies show clear associations between elevated venous pressure and adverse outcomes in critically ill patients. Current venous pressure measurement techniques include physical examination, right heart catheterization (RHC), two-dimensional ultrasound, and a variety of labor-intensive research-focused physiological maneuvers. Each of these techniques have specific shortcomings, limiting their clinical utility. To address these gaps, Beaubien-Souligny et al. introduced the VExUS Score, a novel doppler ultrasound-based method that integrates IVC diameter with doppler measurements of the hepatic, portal, and renal veins to generate a venous congestion assesment. Studies show strong correlations between VExUS score and RHC measurements, and well as an association between VExUS score and improvement in cardiorenal acute kidney injury, diuretic response, and fluid status shifts. However, studies in noncardiac populations have been small, heterogenous, and inconclusive.

SUMMARY

Early studies evaluating the use of doppler ultrasound to assess venous congestion show promise, but further research is needed in diverse patient populations and clinical settings.

Linking preoperative and early intensive care unit data for prolonged intubation prediction

Objectives

Prolonged intubation (PI) is a frequently encountered severe complication among patients following cardiac surgery (CS). Solely concentrating on preoperative data, devoid of sufficient consideration for the ongoing impact of surgical, anesthetic, and cardiopulmonary bypass procedures on subsequent respiratory system function, could potentially compromise the predictive accuracy of disease prognosis. In response to this challenge, we formulated and externally validated an intelligible prediction model tailored for CS patients, leveraging both preoperative information and early intensive care unit (ICU) data to facilitate early prophylaxis for PI.

Methods

We conducted a retrospective cohort study, analyzing adult patients who underwent CS and utilizing data from two publicly available ICU databases, namely, the Medical Information Mart for Intensive Care and the eICU Collaborative Research Database. PI was defined as necessitating intubation for over 24 h. The predictive model was constructed using multivariable logistic regression. External validation of the model's predictive performance was conducted, and the findings were elucidated through visualization techniques.

Results

The incidence rates of PI in the training, testing, and external validation cohorts were 11.8%, 12.1%, and 17.5%, respectively. We identified 11 predictive factors associated with PI following CS: plateau pressure [odds ratio (OR), 1.133; 95% confidence interval (CI), 1.111-1.157], lactate level (OR, 1.131; 95% CI, 1.067-1.2), Charlson Comorbidity Index (OR, 1.166; 95% CI, 1.115-1.219), Sequential Organ Failure Assessment score (OR, 1.096; 95% CI, 1.061-1.132), central venous pressure (OR, 1.052; 95% CI, 1.033-1.073), anion gap (OR, 1.075; 95% CI, 1.043-1.107), positive end-expiratory pressure (OR, 1.087; 95% CI, 1.047-1.129), vasopressor usage (OR, 1.521; 95% CI, 1.23-1.879), Visual Analog Scale score (OR, 0.928; 95% CI, 0.893-0.964), pH value (OR, 0.757; 95% CI, 0.629-0.913), and blood urea nitrogen level (OR, 1.011; 95% CI, 1.003-1.02). The model exhibited an area under the receiver operating characteristic curve (AUROC) of 0.853 (95% CI, 0.840-0.865) in the training cohort, 0.867 (95% CI, 0.853-0.882) in the testing cohort, and 0.704 (95% CI, 0.679-0.727) in the external validation cohort.

Conclusions

Through multicenter internal and external validation, our model, which integrates early ICU data and preoperative information, exhibited outstanding discriminative capability. This integration allows for the accurate assessment of PI risk in the initial phases following CS, facilitating timely interventions to mitigate adverse outcomes.

Point-of-Care Ultrasound for the Diagnosis of Congestive Kidney Due to Severe Acidemia: A Case Report

A 51-year-old woman with mitochondrial myopathy and congestive heart failure with reduced left ventricular ejection fraction was admitted due to loss of appetite and progressive frailty. She presented with acute kidney injury (AKI) and severe acidemia. Given her medical history and physical examination (jugular vein distention was not obvious), prerenal causes (hypovolemia/hypotension) of AKI were considered most likely. However, with a significantly elevated N-terminal pro-b-type natriuretic peptide level of 14,700 pg/mL, a congestive kidney was also considered. Bedside echocardiography showed no evidence of low output syndrome, whereas venous excess ultrasound (VExUS) score was assessed as Grade 2 (moderate congestion). In addition to administering fluids for the suspected prerenal causes (hypovolemia/hypotension), sodium bicarbonate was administered suspecting a negative impact of severe acidemia on cardiac function. With the improvement of acidemia and only a small volume of fluid therapy, there was a rapid improvement in AKI with the normalization of the VExUS score. This suggested that the main cause of AKI was congestive kidney. In this case, VExUS helped us make a correct diagnosis of acidemia-induced congestive kidney rather than hypovolemia as a cause of AKI, leading to the appropriate treatment.

Prospective Evaluation of Venous Excess Ultrasound for Estimation of Venous Congestion

BACKGROUND

Venous excess ultrasound (VExUS) is a novel ultrasound technique previously reported as a noninvasive measure of venous congestion and predictor of cardiorenal acute kidney injury.

RESEARCH QUESTION

Are there associations between VExUS grade and cardiac pressures measured by right heart catheterization (RHC) and cardiac biomarkers and clinical outcomes in patients undergoing RHC?

STUDY DESIGN AND METHODS

We conducted a prospective cohort study at the Denver Health Medical Center from December 20, 2022, to March 25, 2023. All patients undergoing RHC underwent a blinded VExUS assessment prior to their procedure. Multivariable regressions were conducted to assess relationships between VExUS grade and cardiac pressures, biomarkers, and changes in weight among patients with heart failure, a proxy for diuretic success. Receiver operating characteristic curve and area under the curve (AUC) were derived for VExUS, inferior vena cava (IVC) diameter, and IVC collapsibility index (ICI) to predict right atrial pressure (RAP) > 10 and < 7 mm Hg.

RESULTS

Among 81 patients, 45 of whom were inpatients, after adjusting for age, sex, and Charlson Comorbidity Index, there were significant relationships between VexUS grade of 2 (β = 4.8; 95% CI, 2.6-7.1; P < .01) and 3 (β = 11; 95% CI, 8.9-14; P < .01) and RAP, VExUS grade of 2 (β = 6.8; 95% CI, 0.16-13; P = .045) and 3 (β = 15; 95% CI, 7.3-22; P < .01) and mean pulmonary artery pressure, and VExUS grade of 2 (β = 7.0; 95% CI, 3.9-10; P < .01) and 3 (β = 13; 95% CI, 9.5-17; P < .01) and pulmonary capillary wedge pressure. AUC values for VExUS, IVC diameter, and ICI as predictors of RAP > 10 mm Hg were 0.9 (95% CI, 0.83-0.97), 0.77 (95% CI, 0.68-0.88), and 0.65 (95% CI, 0.52-0.78), respectively. AUC values for VExUS, IVC diameter, and ICI as predictors of RAP < 7 mm Hg were 0.79 (95% CI, 0.70-0.87), 0.74 (95% CI, 0.64-0.84), and 0.62 (95% CI, 0.49-0.76), respectively. In a subset of 23 patients with heart failure undergoing diuresis, there was a significant association between VExUS grade 3 and change in weight between time of RHC and discharge (P = .025).

INTERPRETATION

Although more research is required, VExUS has the potential to increase diagnostic and therapeutic capabilities of physicians at the bedside and increase our understanding of the underappreciated problem of venous congestion.

EARLY TRAJECTORY OF VENOUS EXCESS ULTRASOUND SCORE IS ASSOCIATED WITH CLINICAL OUTCOMES OF GENERAL ICU PATIENTS

ABSTRACT

Background: Systemic venous congestion, assessed by the venous excess ultrasound (VExUS) score, has been associated with adverse effects, including acute kidney injury (AKI), in patients with cardiac disease. In general intensive care unit (ICU) patients, the association between VExUS score and outcomes is understudied. We aimed to investigate the association between the trajectory of VExUS score within the first 3 days of ICU admission and the composite clinical outcome of major adverse kidney events within 30 days (MAKE30). Methods: In this prospective observational study, including patients consecutively admitted to the ICU, VExUS score was calculated within 24 h after ICU admission (day 1) and at 48 to 72 h (day 3). D-VExUS was calculated as the difference between the VExUS score on day 3 minus that on day 1. Development of AKI within 7 days and all-cause mortality within 30 days were recorded. Results: A total of 89 patients (62% men; median age, 62 years; median Acute Physiology and Chronic Health Evaluation II score, 24) were included. Sixty (67%) patients developed AKI within 7 days, and 17 (19%) patients died within 30 days after ICU admission. D-VExUS was associated with MAKE30, even after adjustment for confounders (hazard ratio, 2.07; 95% confidence interval, 1.17-3.66; P = 0.01). VExUS scores on days 1 or 3 were not associated with MAKE30. Also, VExUS scores on day 1 or on day 3 and D-VExUS were not associated with development of AKI or mortality. Conclusions: In a general ICU cohort, early trajectory of VExUS score, but not individual VExUS scores at different time points, was associated with the patient-centered MAKE30 outcome. Dynamic changes rather than snapshot measurements may unmask the adverse effects of systemic venous congestion on important clinical outcomes.

Coexistence of a fluid responsive state and venous congestion signals in critically ill patients: a multicenter observational proof-of-concept study

BACKGROUND

Current recommendations support guiding fluid resuscitation through the assessment of fluid responsiveness. Recently, the concept of fluid tolerance and the prevention of venous congestion (VC) have emerged as relevant aspects to be considered to avoid potentially deleterious side effects of fluid resuscitation. However, there is paucity of data on the relationship of fluid responsiveness and VC. This study aims to compare the prevalence of venous congestion in fluid responsive and fluid unresponsive critically ill patients after intensive care (ICU) admission.

METHODS

Multicenter, prospective cross-sectional observational study conducted in three medical-surgical ICUs in Chile. Consecutive mechanically ventilated patients that required vasopressors and admitted < 24 h to ICU were included between November 2022 and June 2023. Patients were assessed simultaneously for fluid responsiveness and VC at a single timepoint. Fluid responsiveness status, VC signals such as central venous pressure, estimation of left ventricular filling pressures, lung, and abdominal ultrasound congestion indexes and relevant clinical data were collected.

RESULTS

Ninety patients were included. Median age was 63 [45-71] years old, and median SOFA score was 9 [7-11]. Thirty-eight percent of the patients were fluid responsive (FR+), while 62% were fluid unresponsive (FR-). The most prevalent diagnosis was sepsis (41%) followed by respiratory failure (22%). The prevalence of at least one VC signal was not significantly different between FR+ and FR- groups (53% vs. 57%, p = 0.69), as well as the proportion of patients with 2 or 3 VC signals (15% vs. 21%, p = 0.4). We found no association between fluid balance, CRT status, or diagnostic group and the presence of VC signals.

CONCLUSIONS

Venous congestion signals were prevalent in both fluid responsive and unresponsive critically ill patients. The presence of venous congestion was not associated with fluid balance or diagnostic group. Further studies should assess the clinical relevance of these results and their potential impact on resuscitation and monitoring practices.

Incidence and Determinants of Acute Kidney Injury after Prone Positioning in Severe COVID-19 Acute Respiratory Distress Syndrome

(1) Background: Acute kidney injury (AKI) is common among critically ill COVID-19 patients, but its temporal association with prone positioning (PP) is still unknown, and no data exist on the possibility of predicting PP-associated AKI from bedside clinical variables. (2) Methods: We analyzed data from 93 COVID-19-related ARDS patients who underwent invasive mechanical ventilation (IMV) and at least one PP cycle. We collected hemodynamic variables, respiratory mechanics, and circulating biomarkers before, during, and after the first PP cycle. PP-associated AKI (PP-AKI) was defined as AKI diagnosed any time from the start of PP to 48 h after returning to the supine position. A t-test for independent samples was used to test for the differences between groups, while binomial logistical regression was performed to assess variables independently associated with PP-associated AKI. (3) Results: A total of 48/93 (52%) patients developed PP-AKI, with a median onset at 24 [13.5-44.5] hours after starting PP. No significant differences in demographic characteristics between groups were found. Before starting the first PP cycle, patients who developed PP-AKI had a significantly lower cumulative fluid balance (CFB), even when normalized for body weight (p = 0.006). Central venous pressure (CVP) values, measured before the first PP (OR 0.803, 95% CI [0.684-0.942], p = 0.007), as well as BMI (OR 1.153, 95% CI = [1.013-1.313], p = 0.031), were independently associated with the development of PP-AKI. In the multivariable regression analysis, a lower CVP before the first PP cycle was independently associated with ventilator-free days (OR 0.271, 95% CI [0.123-0.936], p = 0.011) and with ICU mortality (OR:0.831, 95% CI [0.699-0.989], p = 0.037). (4) Conclusions: Acute kidney injury occurs frequently in invasively ventilated severe COVID-19 ARDS patients undergoing their first prone positioning cycle. Higher BMI and lower CVP before PP are independently associated with the occurrence of AKI during prone positioning.

Correlation of Internal Jugular Vein Collapsibility With Central Venous Pressure in Patients With Liver Cirrhosis

We aimed to compare internal jugular vein and inferior vena cava ultrasonography as predictors of central venous pressure in cirrhotic patients. We performed ultrasound assessments of the internal jugular vein (IJV) and the inferior vena cava and then invasively measured central venous pressure (CVP). We then compared their correlation with CVP and performed area under the receiver operating characteristic curves to determine which had best sensitivity and specificity. IJV cross-sectional area collapsibility index at 30° correlated better with CVP ( r = -0.56, P < 0.001), and an IJV AP-CI at 30° ≤ 24.8% was better at predicting a CVP ≥8 mm Hg, with 100% sensitivity and 97.1% specificity. Thus, IJV point-of-care ultrasound might be superior than inferior vena cava point-of-care ultrasound as a predictor of CVP in cirrhotic patients.

The Effect of Fluid Pre-loading on Vital Signs and Hemodynamic Parameters in a Porcine Model of Lipopolysaccharide-Induced Endotoxemia

Background Animal models of distributive hypotension and resuscitation allow the assessment of hemodynamic monitoring modalities and resuscitation strategies. The fluid-first paradigm for resuscitation is currently being challenged with clinical trials. In this investigation, venous return and perfusion are assessed, and full hemodynamics are characterized, in a porcine model of endotoxemic hypotension with and without fluid pre-loading. Methods Two groups of six pigs had the induction of standardized endotoxemic hypotension ("critical hypotension"). Group 1 underwent four 10 cc/kg crystalloid boluses, and Group 2 was not fluid pre-resuscitated. Both groups underwent progressive norepinephrine (NE) up-titration to 0.25 mcg/kg/minute over 30 minutes. Vital signs, central parameters, and laboratory values were obtained at baseline, "critical hypotension," after each bolus and during NE administration. Results Endotoxemia decreased the systemic vascular resistance (SVR) in Group 1 (1031±106 dyn/s/cm-5 versus 738±258 dyn/s/cm-5; P=0.03) and Group 2 (1121±196 dyn/s/cm-5 versus 759±342 dyn/s/cm-5; P=0.003). In Group 1, the four fluid boluses decreased heart rate (HR), pulmonary capillary wedge pressure (PCWP), and central venous pressure (CVP) (P<0.05). No changes were observed in blood pressure, cardiac output (CO), or lactate. NE up-titration increased HR in Group 1 and decreased CVP in both groups. Higher final CVP (11 {3} versus 4 {4} mmHg; P=0.01) and PCWP (5 {1} versus 2 {2} mmHg; P=0.005) values were observed in Group 1 relative to Group 2, reflecting increased venous return. Conclusions Porcine endotoxemic hypotension and resuscitation were robustly characterized. In this model, fluid loading improved venous return with NE, though perfusion (CO) was preserved by increased NE-induced chronotropy.

Correlation between the VExUS score and right atrial pressure: a pilot prospective observational study

Venous congestion is an under-recognized contributor to mortality in critically ill patients. Unfortunately, venous congestion is difficult to measure, and right heart catheterization (RHC) has been considered the most readily available means for measuring venous filling pressure. Recently, a novel "Venous Excess Ultrasound (VExUS)" score was developed to noninvasively quantify venous congestion using inferior vena cava (IVC) diameter and Doppler flow through the hepatic, portal, and renal veins. A preliminary retrospective study of post-cardiac surgery patients showed promising results, including a high positive-likelihood ratio of high VExUS grade for acute kidney injury. However, studies have not been reported in broader patient populations, and the relationship between VExUS and conventional measures of venous congestion is unknown. To address these gaps, we prospectively assessed the correlation of VExUS with right atrial pressure (RAP), with comparison to inferior vena cava (IVC) diameter. Patients undergoing RHC at Denver Health Medical Center underwent VExUS examination before their procedure. VExUS grades were assigned before RHC, blinding ultrasonographers to RHC outcomes. After controlling for age, sex, and common comorbidities, we observed a significant positive association between RAP and VExUS grade (P < 0.001, R2 = .68). VExUS had a favorable AUC for prediction of a RAP ≥ 12 mmHg (0.99, 95% CI 0.96-1) compared to IVC diameter (0.79, 95% CI 0.65-0.92). These results suggest a strong correlation between VExUS and RAP in a diverse patient population, and support future studies of VExUS as a tool to assess venous congestion and guide management in a spectrum of critical illnesses.

Impact of central venous pressure during the first 24 h and its time-course on the lactate levels and clinical outcomes of patients who underwent coronary artery bypass grafting

Purpose

Previous studies have revealed that elevated mean central venous pressure (CVP) was associated with poor prognosis in specific patient groups. But no study explored the impact of mean CVP on prognosis of patients who underwent coronary artery bypass grafting surgery (CABG). The purpose of this study was to investigate the impacts of elevated CVP and its time-course on clinical outcomes of patients who underwent CABG and potential mechanisms.

Methods

A retrospective cohort study was performed based on the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. We first identified the CVP during specific period with the most predictive value. Patients were categorized into the low-CVP and high-CVP group on the basis of the cut-off value. A propensity score matching was used to adjust covariates. The primary outcome was a 28-day mortality. The secondary outcomes were 1-year mortality and in-hospital mortality, the length of intensive care unit (ICU) stay and hospitalization, acute kidney injury incidence, use of vasopressors, duration of ventilation and oxygen index, and lactate levels and clearance. Patients in the high-CVP group were categorized into the "second day CVP ≤ 13.46 mmHg" group and the "second day CVP > 13.46 mmHg" group, respectively, and the clinical outcomes were the same as before.

Results

A total of 6,255 patients who underwent CABG were picked from the MIMIC-IV database, of which 5,641 CABG patients were monitored by CVP measurement during the first 2 days after ICU admission and 206,016 CVP records were extracted from the database. The mean CVP during the first 24 h was the most correlative and statistically significant for the 28-day mortality. The risk of the 28-day mortality was increased in the high-CVP group [OR 3.45 (95% CI: 1.77-6.70; p < 0.001)]. Patients with elevated CVP levels had worse secondary outcomes. The maximum of lactate levels and lactate clearance were also poor in the high-CVP group. For patients in the high-CVP group during the first 24 h, whose mean CVP during the second day lowered to less than the cut-off value, had better clinical outcomes.

Conclusions

An elevated mean CVP during the first 24 h was correlated with poor outcomes in patients who underwent CABG. The potential mechanisms may be influencing the lactate levels and lactate clearance through the impact on afterload of tissue perfusion. Patients whose mean CVP during the second day dropped to less than the cut-off value had favorable prognosis.

Optimization of central venous pressure during the perioperative period is associated with improved prognosis of high-risk operation patients

Background

While central venous pressure (CVP) measurement is used to guide fluid management for high-risk surgical patients during the perioperative period, its relationship to patient prognosis is unknown.

Methods

This single-center, retrospective observational study enrolled patients undergoing high-risk surgery from February 1, 2014 to November 31, 2020, who were admitted to the surgical intensive care unit (ICU) directly after surgery. Patients were divided into the following three groups according to the first CVP measurement (CVP1) after admission to the ICU: low, CVP1 <8 mmHg; moderate, 8 mmHg≤ CVP1 ≤ 12 mmHg; and high, CVP1 >12 mmHg. Perioperative fluid balance, 28-day mortality, length of stay in the ICU, and hospitalization and surgical complications were compared across groups.

Results

Of the 775 high-risk surgical patients enrolled in the study, 228 were included in the analysis. Median (interquartile range) positive fluid balance during surgery was lowest in the low CVP1 group and highest in the high CVP1 group (low CVP1: 770 [410, 1205] mL; moderate CVP1: 1070 [685, 1500] mL; high CVP1: 1570 [1008, 2000] mL; all P <0.001). The volume of positive fluid balance during the perioperative period was correlated with CVP1 (r=0.336, P <0.001). The partial arterial pressure of oxygen(PaO₂)/fraction of inspired oxygen(FiO₂) ratio was significantly lower in the high CVP1 group than in the low and moderate CVP1 groups (low CVP1: 400.0 [299.5, 443.3] mmHg; moderate CVP1: 362.5 [330.0, 434.9] mmHg; high CVP1: 335.3 [254.0, 363.5] mmHg; all P <0.001). The incidence of postoperative acute kidney injury (AKI) was lowest in the moderate CVP1 group (low CVP1: 9.2%; moderate CVP1: 2.7%; high CVP1: 16.0%; P=0.007). The proportion of patients receiving renal replacement therapy was highest in the high CVP1 group (low CVP1: 1.5%; moderate CVP1: 0.9%; high CVP1: 10.0%; P=0.014). Logistic regression analysis showed that intraoperative hypotension and CVP1 >12 mmHg were risk factors for AKI within 72 h after surgery (adjusted odds ratio[aOR]=3.875, 95% confidence interval[CI]: 1.378-10.900, P=0.010 and aOR=1.147, 95%CI: 1.006-1.309, P=0.041).

Conclusions

CVP that is either too high or too low increases the incidence of postoperative AKI. Sequential fluid therapy based on CVP after patients are transferred to the ICU post-surgery does not reduce the risk of organ dysfunction caused by an excessive amount of intraoperative fluid. However, CVP can be used as a safety limit indicator for perioperative fluid management in high-risk surgical patients.

Diuretics depletion improves cardiac output and ventriculo-arterial coupling in congestive ICU patients during hemodynamic de-escalation

PURPOSE

Congestion was shown to hamper organ perfusion, but the exact timing of diuretic initiation during hemodynamic de-escalation in shock is unclear. The aim of this study was to describe the hemodynamic effects of diuretic initiation in the stabilized shock.

METHODS

We performed a monocentric, retrospective analysis, in a cardiovascular medico-surgical ICU. We included consecutive resuscitated adult patients, for whom the clinician decided to introduce loop diuretic treatment for clinical signs of fluid overload. The patients were hemodynamically evaluated at the moment of diuretic introduction and 24 h later.

RESULTS

Seventy ICU patients were included in this study, with a median duration of ICU stay before diuretic initiation of 2 [1-3] days. 51(73%) patients were classified as congestive (central venous pressure > 12 mmHg). After treatment, the cardiac index increased towards normal values in the congestive group (2.7 ± 0.8 L min^- 1 m^- 2 from 2.5 ± 0.8 L min^- 1 m^- 2, p = 0.042), but not in the non-congestive group (2.7 ± 0.7 L min^- 1 m^- 2 from baseline 2.7 ± 0.8 L min^- 1 m^- 2, p = 0.968). A decrease in arterial lactate concentrations was observed in the congestive group (2.1 ± 2 mmol L^- 1 vs. 1.3 ± 0.6 mmol L^- 1, p < 0.001). The diuretic therapy was associated with an improvement of ventriculo-arterial coupling comparing with baseline values in the congestive group (1.69 ± 1 vs. 1.92 ± 1.5, p = 0.03). The norepinephrine use decreased in congestive patients (p = 0.021), but not in the non-congestive group (p = 0.467).

CONCLUSION

The initiation of diuretics in ICU congestive patients with stabilized shock was associated with improvement of cardiac index, ventriculo-arterial coupling, and tissue perfusion parameter. These effects were not observed in non-congestive patients.

Whale Optimization Algorithm with a Hybrid Relation Vector Machine: A Highly Robust Respiratory Rate Prediction Model Using Photoplethysmography Signals

Due to the simplicity and convenience of PPG signal acquisition, the detection of the respiration rate based on the PPG signal is more suitable for dynamic monitoring than the impedance spirometry method, but it is challenging to achieve accurate predictions from low-signal-quality PPG signals, especially in intensive-care patients with weak PPG signals. The goal of this study was to construct a simple model for respiration rate estimation based on PPG signals using a machine-learning approach fusing signal quality metrics to improve the accuracy of estimation despite the low-signal-quality PPG signals. In this study, we propose a method based on the whale optimization algorithm (WOA) with a hybrid relation vector machine (HRVM) to construct a highly robust model considering signal quality factors to estimate RR from PPG signals in real time. To detect the performance of the proposed model, we simultaneously recorded PPG signals and impedance respiratory rates obtained from the BIDMC dataset. The results of the respiration rate prediction model proposed in this study showed that the MAE and RMSE were 0.71 and 0.99 breaths/min, respectively, in the training set, and 1.24 and 1.79 breaths/min, respectively, in the test set. Compared without taking signal quality factors into account, MAE and RMSE are reduced by 1.28 and 1.67 breaths/min, respectively, in the training set, and reduced by 0.62 and 0.65 breaths/min in the test set. Even in the nonnormal breathing range below 12 bpm and above 24 bpm, the MAE reached 2.68 and 4.28 breaths/min, respectively, and the RMSE reached 3.52 and 5.01 breaths/min, respectively. The results show that the model that considers the PPG signal quality and respiratory quality proposed in this study has obvious advantages and application potential in predicting the respiration rate to cope with the problem of low signal quality.

The magnitude, but not the duration of elevated central venous pressure is associated with mortality in sepsis patients: An analysis of the MIMIC-IV database

BACKGROUND

It is unclear whether the magnitude and duration of elevated central venous pressure (ECVP) greater than ten mmHg has the same impact on mortality in sepsis patients.

METHODS

Critically ill patients with sepsis were identified from the Medical Information Mart for Intensive Care (MIMIC)-IV database. The duration and the magnitude of ECVP were calculated. Normalized ECVP load was defined as the ECVP load (the sum of ECVP value times its duration) divided by the total duration of ECVP. The primary endpoint was 28-day mortality. Kaplan-Meier survival analysis was used to compare survival between patients with high or low normalized ECVP load.

RESULTS

A total of 1071 sepsis patients were included. Higher normalized ECVP load was associated with higher mortality rate; in contrast, the duration of ECVP was not associated with mortality. A linear relationship between normalized ECVP load and mortality was identified. Patients with higher normalized ECVP load had less urine output and more positive fluid balance.

CONCLUSION

The magnitude, but not the duration of ECVP, is associated with mortality in sepsis patients. ECVP should be considered as a valuable and easily accessible safety parameter during fluid resuscitation.

Association Between Wait Time of Central Venous Pressure Measurement and Outcomes in Critical Patients With Acute Kidney Injury: A Retrospective Cohort Study

Background

Hemodynamic management is of paramount importance in patients with acute kidney injury (AKI). Central venous pressure (CVP) has been used to assess volume status. We intended to identify the optimal time window in which to obtain CVP to avoid the incidence of adverse outcomes in patients with AKI.

Methods

The study was based on the Medical Information Mart for Intensive Care (MIMIC) IV database. The primary outcome was in-hospital mortality. Secondary outcomes included the number of ICU-free days and norepinephrine-free days at 28 days after ICU admission, and total fluid input and fluid balance during the first and second day. A time-dose-response relationship between wait time of CVP measurement and in-hospital mortality was implemented to find an inflection point for grouping, followed by propensity-score matching (PSM), which was used to compare the outcomes between the two groups.

Results

Twenty Nine Thousand and Three Hundred Thirty Six patients with AKI were enrolled, and the risk of in-hospital mortality increased when the CVP acquisition time was >9 h in the Cox proportional hazards regression model. Compared with 8,071 patients (27.5%) who underwent CVP measurement within 9 h and were assigned to the early group, 21,265 patients (72.5%) who delayed or did not monitor CVP had a significantly higher in-hospital mortality in univariate and multivariate Cox regression analyses. After adjusting for potential confounders by PSM and adjusting for propensity score, pairwise algorithmic, overlap weight, and doubly robust analysis, the results were still stable. The HRs were 0.58-0.72, all p < 0.001. E-value analysis suggested robustness to unmeasured confounding.

Conclusions

Among adults with AKI in ICU, increased CVP wait time was associated with a greater risk of in-hospital mortality. In addition, early CVP monitoring perhaps contributed to shortening the length of ICU stays and days of norepinephrine use, as well as better fluid management.

Accuracy of echocardiographic estimations of right heart pressures in adult heart transplant recipients

BACKGROUND

Accurate assessment of right atrial pressure (RAP) and pulmonary artery systolic pressure (PASP) is critical in the management of heart transplant recipients. The accuracy of echocardiography in estimating these pressures has been debated.

OBJECTIVE

To assess the correlation and agreement between echocardiographic estimations of right heart pressures with those of respective invasive hemodynamic measurements by right heart catheterization (RHC) in adult heart transplant recipients.

METHODS

This is a prospective evaluation of 84 unique measurements from heart transplant recipients who underwent RHC followed by standard echocardiographic evaluation within 159 ± 64 min with no intervening medication changes. The relationship between noninvasive pressure estimations and invasive hemodynamic measurements was examined.

RESULTS

Mean RAP was 7 ± 5 mmHg and mean PASP was 33 ± 8 mmHg by RHC. There was no significant correlation between echocardiographic estimation of RAP and invasive RAP (Spearman's rho = -0.05, p = .7), and no significant agreement between these two variables (weighted kappa = -0.1). There was a modest correlation between echocardiographic estimation of PASP and invasive PASP (r = .39, p = .002). Bland-Altman analysis showed a mean bias of 2.1 ± 9 mmHg (limits of agreement = -15 to 20 mmHg).

CONCLUSION

In heart transplant recipients, there is no significant correlation or agreement between echocardiographic RAP estimation and invasively determined RAP. Noninvasive PASP estimation correlates significantly but modestly with invasively measured PASP. Further refinement of echocardiographic methods for assessment of RAP is warranted in this unique patient population.

Central Venous Pressure Measurement Is Associated With Improved Outcomes in Patients With or at Risk for Acute Respiratory Distress Syndrome: An Analysis of the Medical Information Mart for Intensive Care IV Database

Background

Central venous pressure (CVP) monitoring is widely used in the intensive care unit (ICU). However, the formal utility of CVP measurement to altering patient outcomes among ICU patients with or at risk for acute respiratory distress syndrome (ARDS) has never been investigated. Our study aimed to explore the association of CVP measurement with 28-day mortality specifically in that population.

Methods

This study was based on the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. Patients were divided into CVP and no CVP groups according to whether they had CVP measurement within 24 h of admission to the ICU. The primary outcome was 28-day mortality. Multivariate regression was used to elucidate the association between CVP measurement and 28-day mortality, and propensity score matching (PSM) and propensity score-based overlap weighting (OW) were employed to verify the stability of our results.

Results

A total of 10,198 patients with or at risk for ARDS were included in our study, of which 4,647 patients (45.6%) belonged to the CVP group. Multivariate logistic regression showed that the early measurement of CVP was independently associated with lower 28-day mortality (OR: 0.49; 95% CI: 0.42–0.57; p < 0.001). This association remained robust after PSM and OW (both p < 0.001). Patients in the CVP group had shorter ICU stay, lower in-hospital mortality, more fluid on day 1 and higher clearance of blood lactate than those in the no CVP group.

Conclusion

Early CVP measurement is associated with an improvement in 28-day mortality among a general population of critically ill patients with or at risk for ARDS.

High Central Venous Pressure Associated with Mortality in Intensive Care Unit

BACKGROUND: Central venous pressure (CVP) has been used as a measurement tool to assess hemodynamics, medication, and nutritional status in critically ill patients for decades. We frequently use the Acute Physiology and Chronic Health Evaluation or Sequential Organ Failure Assessment score to predict the mortality of intensive care unit (ICU) patients. Unfortunately, it requires a lot of time and procedures to measure these parameters. Moreover, not every single hospital can apply these scores. Since CVP is widely used in ICU, we can use the value of CVP to predict mortality. AIM: The aim of this study was to find the correlation between CVP and mortality rate. METHODS: This cross-sectional study was conducted in ICU of Haji Adam Malik General Hospital, Medan, in 2017. Basic demographic data, CVP measurements and mortality were recorded among all ICU patients. Patients with CVP >12 mmHg were considered high. The association between CVP and mortality was analyzed. RESULTS: One hundred patients were admitted during the study period with mortality rate of 38%. The most common cause of ICU admission was postoperative neurosurgical patients (28%). We found correlation between high CVP (>12 mmHg) and mortality among ICU patients (odds ratio: 3.372; 95% confidence interval: 1.349–8.428; p = 0.008) CONCLUSION: CVP level >12 mmHg associated with higher mortality rate in ICU patients.

Novel Methods for Predicting Fluid Responsiveness in Critically Ill Patients—A Narrative Review

In patients with acute circulatory failure, fluid administration represents a first-line therapeutic intervention for improving cardiac output. However, only approximately 50% of patients respond to fluid infusion with a significant increase in cardiac output, defined as fluid responsiveness. Additionally, excessive volume expansion and associated hyperhydration have been shown to increase morbidity and mortality in critically ill patients. Thus, except for cases of obvious hypovolaemia, fluid responsiveness should be routinely tested prior to fluid administration. Static markers of cardiac preload, such as central venous pressure or pulmonary artery wedge pressure, have been shown to be poor predictors of fluid responsiveness despite their widespread use to guide fluid therapy. Dynamic tests including parameters of aortic blood flow or respiratory variability of inferior vena cava diameter provide much higher diagnostic accuracy. Nevertheless, they are also burdened with several significant limitations, reducing the reliability, or even precluding their use in many clinical scenarios. This non-systematic narrative review aims to provide an update on the novel, less employed dynamic tests of fluid responsiveness evaluation in critically ill patients.

POCUS in Intensive Care Nephrology

Acute kidney injury (AKI) is a significant problem for patients admitted to the intensive care unit (ICU), both due to the high incidence and associated mortality with rates of AKI requiring renal replacement therapy (RRT) of over 5%, and mortality rates with AKI of over 60% 1, 2.Ultrasound can be used to identify those at risk for AKI and assist with AKI management. Risk factors for AKI in the ICU not only include hypoperfusion but also venous congestion and volume overload. Volume overload and vascular congestion are associated with multi-organ dysfunction and worse renal outcomes. Daily and overall fluid balance, daily weights, and physical examination for edema can be inaccurate and belie true systemic venous pressure 3, 4, 5. Bedside ultrasound allows providers to evaluate vascular flow patterns and obtain a more reliable evaluation of volume status to guide and individualize therapies. Cardiac, lung, and vascular patterns on ultrasound can identify preload responsiveness, which should be assessed to safely manage ongoing fluid resuscitation and assess for signs of fluid intolerance. Here we present an overview in the use of point of care ultrasound with particular emphasis on nephro-centric strategies, namely in the identification of the type of renal injury, renal vascular flow assessment, the static measure of volume status, as well as dynamic evaluation for volume optimization in critically ill patients.

Haemodynamic predisposition to acute kidney injury: Shadow and light!

Acute kidney injury (AKI) could well be regarded as a sentinel complication given it is relatively common and associated with a substantial risk of subsequent morbidity and mortality. On the aegis of 'prevention is better than cure', there has been a wide interest in evaluating haemodynamic predisposition to AKI so as to provide a favourable renoprotective haemodynamic milieu to the subset of patients presenting a significant risk of developing AKI. In this context, the last decade has witnessed a series of evaluation of the hypotension value and duration cut-offs associated with risk of AKI across diverse non-operative and operative settings. Nevertheless, a holistic comprehension of the haemodynamic predisposition to AKI has been a laggard with only few reports highlighting the potential of elevated central venous pressure, intra-abdominal hypertension and high mean airway pressures in considerably attenuating the effective renal perfusion, particularly in scenarios where kidneys are highly sensitive to any untoward elevation in the afterload. Despite the inherent autoregulatory mechanisms, the effective renal perfusion pressure (RPP) can be modulated by a number of haemodynamic factors in addition to mean arterial pressure (MAP) as the escalation of renal interstitial pressure, in particular hampers kidney perfusion which in itself is a dynamic interplay of a number of innate pressures. The present article aims to review the subject of haemodynamic predisposition to AKI centralising the focus on effective RPP (over and above the conventional 'tunnel-vision' for MAP) and discuss the relevant literature accumulating in this area of ever-growing clinical interest.

Portal Vein Pulsatility as a Dynamic Marker of Venous Congestion Following Cardiac Surgery: An Interventional Study Using Positive End-Expiratory Pressure

We aimed to assess variations in the portal vein pulsatility index (PI) during mechanical ventilation following cardiac surgery. Method. After ethical approval, we conducted a prospective monocentric study at Amiens University Hospital. Patients under mechanical ventilation following cardiac surgery were enrolled. Doppler evaluation of the portal vein (PV) was performed by transthoracic echography. The maximum velocity (VMAX) and minimum velocity (VMIN) of the PV were measured in pulsed Doppler mode. The PI was calculated using the following formula (VMAX − VMIN)/(VMax). A positive end-expiratory pressure (PEEP) incremental trial was performed from 0 to 15 cmH₂O, with increments of 5 cmH₂O. The PI (%) was assessed at baseline and PEEP 5, 10, and 15 cmH₂O. Echocardiographic and hemodynamic parameters were recorded. Results. In total, 144 patients were screened from February 2018 to March 2019 and 29 were enrolled. Central venous pressure significantly increased for each PEEP increment. Stroke volumes were significantly lower after PEEP incrementation, with 52 mL (50–55) at PEEP 0 cmH₂O and 30 mL (25–45) at PEEP 15 cmH₂O, (p < 0.0001). The PI significantly increased with PEEP incrementation, from 9% (5–15) at PEEP 0 cmH₂O to 15% (5–22) at PEEP 5 cmH₂O, 34% (23–44) at PEEP 10 cmH₂O, and 45% (25–49) at PEEP 15 cmH₂O (p < 0.001). Conclusion. In the present study, PI appears to be a dynamic marker of the interaction between mechanical ventilation and right heart pressure after cardiac surgery. The PI could be a useful noninvasive tool to monitor venous congestion associated with mechanical ventilation.

Association Between the Central Venous Pressure and All-Cause Mortality in Critically Ill Patients with Acute Kidney Injury

Purpose

Elevated central venous pressure (CVP) plays an important role in the occurrence of acute kidney injury (AKI) and it is also independently associated with the prognosis of critically ill patients. However, the effect of CVP on critically ill AKI patients remains unclear. In this study, we analyzed the relationship between CVP and all-cause mortality of critically ill patients with AKI.

Patients and Methods

The clinical data of patients in intensive care unit (ICU) were retrieved from the Medical Information Mart for Intensive Care III (MIMIC-III) database and retrospectively analyzed. The all-cause mortality for up to 90 days was the main observed outcome. We used the minimum CVP value obtained during the first 72 hours after ICU admission for our analysis and patients were grouped according to this parameter. Patients were also analyzed after being further divided according to stages 1, 2 and 3 of AKI. Multiple Cox regression and Kaplan–Meier analyses were used to explore the association between CVP measurements and death of ICU patients with AKI.

Results

A total of 1986 ICU patients with AKI were studied. A total of 527 (26.5%) patients died by day 90. The high CVP group (patients with ≥10 mmHg) had the lowest 90-day survival rate (P =0.001 by log rank test) when according to Kaplan–Meier analysis. By using Cox regression analysis, high CVP was found to be linked to an increase in mortality (CVP ≥10 mmHg versus ≤5 mmHg, HR, 1.336, 95% CI, 1.064 to 1.677, P trend=0.014). Furthermore, when using in a multivariate Cox regression analysis with CVP as a continuous variable, the higher CVP levels were still an independent risk factor for 90-day all-cause mortality (per 1 mmHg increase, HR, 1.031, 95% CI, 1.013–1.049, P=0.001). In subgroup analysis, a similar trend was observed in patients with AKI stages 2 and 3.

Conclusion

The minimum CVP level during the first 72h after ICU admission was positively associated with mortality in critically ill patients with AKI and this more marked in cases with severe AKI.

High Central Venous Pressure after Cardiac Surgery Might Depict Hemodynamic Deterioration Associated with Increased Morbidity and Mortality

Background: Cardiac surgery patients represent a high-risk cohort in intensive care units (ICUs). Central venous pressure (CVP) measurement seems to remain an integral part in hemodynamic monitoring, especially in cardio-surgical ICUs. However, its value as a prognostic marker for organ failure is still unclear. Therefore, we analyzed postoperative CVP values after adult cardiac surgery in a large cohort with regard to its prognostic value for morbidity and mortality. Methods: All adult patients admitted to our ICUs between 2006 and 2019 after cardiac surgery were eligible for inclusion in the study (n = 11,198). We calculated the median initial CVP (miCVP) after admission to the ICU, which returned valid values for 9802 patients. An ROC curve analysis for optimal cut-off miCVP to predict ICU mortality was conducted with consecutive patient allocation into a (a) low miCVP (LCVP) group (≤11 mmHg) and (b) high miCVP (HCVP) group (>11 mmHg). We analyzed the impact of high miCVP on morbidity and mortality by propensity score matching (PSM) and logistic regression. Results: ICU mortality was increased in HCVP patients. In addition, patients in the HCVP group required longer mechanical ventilation, had a higher incidence of acute kidney injury, were more frequently treated with renal replacement therapy, and showed a higher risk for postoperative liver dysfunction, parametrized by a postoperative rise of ≥ 10 in MELD Score. Multiple regression analysis confirmed HCVP has an effect on postoperative ICU-mortality and intrahospital mortality, which seems to be independent. Conclusions: A high initial CVP in the early postoperative ICU course after cardiac surgery is associated with worse patient outcome. Whether or not CVP, as a readily and constantly available hemodynamic parameter, should promote clinical efforts regarding diagnostics and/or treatment, warrants further investigations.

How I Do It: Risks and Benefits of Fluid Administration as Assessed by Ultrasound

For patients in shock, decisions regarding administering or withholding IV fluids are both difficult and important. Although a strategy of relatively liberal fluid administration has traditionally been popular, recent trial results suggest that moving to a more fluid-restrictive approach may be prudent. The goal of this article was to outline how whole-body point-of-care ultrasound can help clarify both the possible benefits and the potential risks of fluid administration, aiding in the risk/benefit calculations that should always accompany fluid-related decisions.

Assessment of Fluid Status by Bioimpedance Analysis and Central Venous Pressure Measurement and Their Association with the Outcomes of Severe Acute Kidney Injury

Background and Objectives: Fluid disbalance is associated with adverse outcomes in critically ill patients with acute kidney injury (AKI). In this study, we intended to assess fluid status using bioimpedance analysis (BIA) and central venous pressure (CVP) measurement and to evaluate the association between hyperhydration and hypervolemia with the outcomes of severe AKI. Materials and Methods: A prospective study was conducted in the Hospital of the Lithuanian University of Health Sciences Kauno Klinikos. Forty-seven patients treated at the Intensive Care Unit (ICU) with severe AKI and a need for renal replacement therapy (RRT) were examined. The hydration level was evaluated according to the ratio of extracellular water to total body water (ECW/TBW) of bioimpedance analysis and volemia was measured according to CVP. All of the patients were tested before the first hemodialysis (HD) procedure. Hyperhydration was defined as ECW/TBW > 0.39 and hypervolemia as CVP > 12 cm H₂O. Results: According to bioimpedance analysis, 72.3% (n = 34) of patients were hyperhydrated. According to CVP, only 51.1% (n = 24) of the patients were hypervolemic. Interestingly, 69.6% of hypovolemic/normovolemic patients were also hyperhydrated. Of all study patients, 57.4% (n = 27) died, in 29.8% (n = 14) the kidney function improved, and in 12.8% (n = 6) the demand for RRT remained after in-patient treatment. A tendency of higher mortality in hyperhydrated patients was observed, but no association between hypervolemia and outcomes of severe AKI was established. Conclusions: Three-fourths of the patients with severe AKI were hyperhydrated based on bioimpedance analysis. However, according to CVP, only half of these patients were hypervolemic. A tendency of higher mortality in hyperhydrated patients was observed.

Fluctuations of driving pressure during mechanical ventilation indicates elevated central venous pressure and poor outcomes

Inappropriate mechanical ventilation may induce hemodynamic alterations through cardiopulmonary interactions. The aim of this study was to explore the relationship between airway pressure and central venous pressure during the first 72 h of mechanical ventilation and its relevance to patient outcomes. We conducted a retrospective study of the Department of Critical Care Medicine of Peking Union Medical College Hospital and a secondary analysis of the MIMIC-III clinical database. The relationship between the ranges of driving pressure and central venous pressure during the first 72 h and their associations with prognosis were investigated. Data from 2790 patients were analyzed. Wide range of driving airway pressure (odds ratio, 1.0681; 95% CI, 1.0415-1.0953; p < 0.0001) were independently associated with mortality, ventilator-free time, intensive care unit and hospital length of stay. Furthermore, wide range of driving pressure and elevated central venous pressure exhibited a close correlation. The area under receiver operating characteristic demonstrated that range of driving pressure and central venous pressure were measured at 0.689 (95% CI, 0.670-0.707) and 0.681 (95% CI, 0.662-0.699), respectively. Patients with high ranges of driving pressure and elevated central venous pressure had worse outcomes. Post hoc tests showed significant differences in 28-day survival rates (log-rank (Mantel-Cox), 184.7; p < 0.001). In conclusion, during the first 72 h of mechanical ventilation, patients with hypoxia with fluctuating driving airway pressure have elevated central venous pressure and worse outcomes.

Central venous pressure, global end-diastolic index, and the inferior vena cava collapsibility/distensibility indices to estimate intravascular volume status in critically ill children: A pilot study

BACKGROUND

The assessment of the volume status in critically ill paediatric patients in intensive care units is vitally important for fluid therapy management. The most commonly used parameter for detecting volume status is still central venous pressure (CVP); however, in recent years, various kinds of methods and devices are being used for volume assessment in intensive care units.

OBJECTIVES

We aimed to evaluate the relationship between CVP, the global end-diastolic index (GEDI), and ultrasound measurements of the collapsibility and distensibility indices of the inferior vena cava (IVC) in paediatric patients undergoing Pulse index Contour Cardiac Output (PiCCO) monitoring.

METHODS

Fifteen patients receiving PiCCO monitoring were prospectively included in the study. Forty-nine PiCCO measurements were evaluated, and simultaneous CVP values were noted. After each measurement, IVC collapsibility (in spontaneously breathing patients) and distensibility (in mechanically ventilated patients) indices were measured with bedside ultrasound.

RESULTS

The mean age was 93.2 ± 61.3 months. Significant and negative correlations of the GEDI were found with the IVC collapsibility index (in spontaneously breathing patients) and the IVC distensibility index (in mechanically ventilated patients) (r = -0.502, p < 0.001; r = -0.522, p = 0.001, respectively). A significant and weakly positive correlation was found between the GEDI and CVP (r = 0.346, p = 0.015), and a significant and negative correlation was found between the IVC collapsibility index and CVP (r = -0.482, p = 0.03). The correlation between the IVC distensibility index and CVP was significant and negative (r = -0.412, p = 0.04).

CONCLUSION

The use of PiCCO as an advanced haemodynamic monitoring method and the use of bedside ultrasound as a noninvasive method are useful to evaluate the volume status in critically ill paediatric patients in intensive care. These methods will gradually come to the fore in paediatric intensive care.

Ultrasonographic inferior vena cava collapsibility and distensibility indices for detecting the volume status of critically ill pediatric patients

Especially in recent years, the use of point-of-care ultrasound by non-radiologist clinicians has become widespread. Point-of-care ultrasound provides rapid responses to the problems of critically ill patients at the bedside. This technique has many important advantages, including being non-invasive, cheap, repeatable, painless, and radiation-free. Numerous studies have revealed the most important clinical benefits of point-of-care ultrasound use by pediatric intensive care providers. The inferior vena cava is a vessel that is highly sensitive to fluid changes. The inferior vena cava diameter can be measured by a point-of-care ultrasound, and represents a critical parameter in assessing the patient’s fluid status. The inferior vena cava collapsibility index (in spontaneously breathing patients) and the inferior vena cava distensibility index (in mechanically ventilated patients) are calculated by determined formulas by using maximum and minimum diameters of the inferior vena cava. The indices are important guides for pediatric intensive care providers for managing their patients’ fluid treatment. Although some authors claim it is not a reliable method, the technique is coming to fore in intensive care units day by day, and has an increasing trend among pediatric intensive care specialists. Here, we aim to give detailed information on the ultrasonographic inferior vena cava diameter measurement methods, and calculations of the inferior vena cava collapsibility index and inferior vena cava distensibility index, and emphasize the importance of a noninvasive, bedside, and objective method of detecting the volume status of critically ill patients for pediatric intensive care specialists according to the published literature.

A lactate-targeted resuscitation strategy may be associated with higher mortality in patients with septic shock and normal capillary refill time: a post hoc analysis of the ANDROMEDA-SHOCK study

Background

Capillary refill time (CRT) may improve more rapidly than lactate in response to increments in systemic flow. Therefore, it can be assessed more frequently during septic shock (SS) resuscitation. Hyperlactatemia, in contrast, exhibits a slower recovery in SS survivors, probably explained by the delayed resolution of non-hypoperfusion-related sources. Thus, targeting lactate normalization may be associated with impaired outcomes. The ANDROMEDA-SHOCK trial compared CRT- versus lactate-targeted resuscitation in early SS. CRT-targeted resuscitation associated with lower mortality and organ dysfunction; mechanisms were not investigated. CRT was assessed every 30 min and lactate every 2 h during the 8-h intervention period, allowing a first comparison between groups at 2 h (T2). Our primary aim was to determine if SS patients evolving with normal CRT at T2 after randomization (T0) exhibited a higher mortality and organ dysfunction when allocated to the LT arm than when randomized to the CRT arm. Our secondary aim was to determine if those patients with normal CRT at T2 had received more therapeutic interventions when randomized to the LT arm. To address these issues, we performed a post hoc analysis of the ANDROMEDA-SHOCK dataset.

Results

Patients randomized to the lactate arm at T0, evolving with normal CRT at T2 exhibited significantly higher mortality than patients with normal CRT at T2 initially allocated to CRT (40 vs 23%, p = 0.009). These results replicated at T8 and T24. LT arm received significantly more resuscitative interventions (fluid boluses: 1000[500–2000] vs. 500[0–1500], p = 0.004; norepinephrine test in previously hypertensive patients: 43 (35) vs. 19 (19), p = 0.001; and inodilators: 16 (13) vs. 3 (3), p = 0.003). A multivariate logistic regression of patients with normal CRT at T2, including APACHE-II, baseline lactate, cumulative fluids administered since emergency admission, source of infection, and randomization group) confirmed that allocation to LT group was a statistically significant determinant of 28-day mortality (OR 3.3; 95%CI[1.5–7.1]); p = 0.003).

Conclusions

Septic shock patients with normal CRT at baseline received more therapeutic interventions and presented more organ dysfunction when allocated to the lactate group. This could associate with worse outcomes.

Pulmonary hypertension with adult respiratory distress syndrome: prevalence, clinical impact, and association with central venous pressure

Pulmonary hypertension (PH) occurs in patients with acute respiratory distress syndrome (ARDS); the most severe form comprises acute cor pulmonale (ACP). Here, we investigated the prevalence of PH in patients with ARDS to evaluate its correlation with ACP risk, ARDS severity and central venous pressure (CVP). We conducted a secondary analysis using data from the MIMIC-III open-source clinical database. The prevalence of PH associated with new-onset ARDS during the first 72 h after intensive care unit admission was investigated; moreover, the association between ACP risk score and PH was validated. We also evaluated the association between elevated CVP (mean CVP > 10 mmHg) and PH and other clinical outcomes. Among 2434 patients who met the ARDS Berlin criteria and underwent echocardiography or pulmonary artery catheterization evaluation, a total of 583 (24.0%) patients were diagnosed with moderate or severe PH, of which 418 had low and 165 had high ACP risk. After adjustment for disease/ARDS severity, ACP risk score, and other demographic variables, elevated CVP was independently associated with the occurrence of PH (odds ratio, 2.239 (1.674, 2.993), p < 0.005). Among patients with PH, higher mean CVP was associated with prolonged hospital stay (13.4 vs. 15.2 days, p = 0.041) and duration of ventilation (116.5 vs. 150.5 h, p = 0.023). Incidence of PH was 24.0% in patients with new-onset ARDS in this retrospective study. Elevated CVP is relevant with higher incidence of PH and worse clinical outcome; these highlighted the importance of hemodynamic monitoring in the management of ARDS.

Effects of Quality Control Targets (SpO2≠100%, PaCO2/<40 mmHg, Pmean/>10 cmH2O) on Outcomes in Patients in the ICU

Objectives: A series of quality control (QC) targets (SpO2≠100%, PaCO2≮40 mmHg, Pmean≯10 cmH2O) was put forward and widely used in a single intensive care unit (ICU) setting. The aim of this study was to assess whether these QC targets could improve the outcomes of critically ill patients. Methods: The real-time clinical data of patients undergoing mechanical ventilation at ICU admission between May 2013 and May 2017 in the Department of Critical Care Medicine of Peking Union Medical College Hospital were collected and analyzed. Results: A total of 7,670 patients [mean age, 58 years; 3,943 (51.5%) male] were divided into the before QC (n = 3,936) and after QC (n = 3,734) groups. QC targets (SpO2, PaCO2, and Pmean) and respiratory parameters (FiO2%, PaO2, PEEP, tidal volume, and respiratory rate) within 72 h of ICU admission, primary outcomes (ICU mortality, 28-, 60-, and 90-day mortality) and secondary outcomes (discharge against medical advice, ICU admission days, mechanical ventilation times, and central venous pressure) were measured and compared between the before and after QC groups. The 72 h average of the Pmean, FiO2%, PaO2, and VT were significantly lower and PaCO2 was higher in the after QC than in the before QC group (P < 0.05). A lower 90-day mortality rate, less discharge against medical advice, fewer ICU admission days, and reduced mechanical ventilation times were found in the after QC group compared with the before QC group (P < 0.05). Interestingly, CVP was significantly lower in the after QC group than in the before QC group (P < 0.05). Conclusions: The QC targets (SpO2≠100%, PaCO2≮40 mmHg, Pmean≯10 cmH2O) contributed to avoiding high oxygen level hazards, protecting against lung injury, and improving circulatory function, which resulted in a better prognosis of critically ill patients.

Quantifying systemic congestion with Point-Of-Care ultrasound: development of the venous excess ultrasound grading system

Background

Organ congestion is a mediator of adverse outcomes in critically ill patients. Point-Of-Care ultrasound (POCUS) is widely available and could enable clinicians to detect signs of venous congestion at the bedside. The aim of this study was to develop several grading system prototypes using POCUS and to determine their respective ability to predict acute kidney injury (AKI) after cardiac surgery. This is a post-hoc analysis of a single-center prospective study in 145 patients undergoing cardiac surgery for which repeated daily measurements of hepatic, portal, intra-renal vein Doppler and inferior vena cava (IVC) ultrasound were performed during the first 72 h after surgery. Five prototypes of venous excess ultrasound (VExUS) grading system combining multiple ultrasound markers were developed.

Results

The association between each score and AKI was assessed using time-dependant Cox models as well as conventional performance measures of diagnostic testing. A total of 706 ultrasound assessments were analyzed. We found that defining severe venous congestion as the presence of severe flow abnormalities in multiple Doppler patterns with a dilated IVC (≥ 2 cm) showed the strongest association with the development of subsequent AKI compared with other combinations (HR: 3.69 CI 1.65–8.24 p = 0.001). The association remained significant after adjustment for baseline risk of AKI and vasopressor/inotropic support (HR: 2.82 CI 1.21–6.55 p = 0.02). Furthermore, this severe VExUS grade offered a useful positive likelihood ratio (+LR: 6.37 CI 2.19–18.50) when detected at ICU admission, which outperformed central venous pressure measurements.

Conclusions

The combination of multiple POCUS markers may identify clinically significant venous congestion.

Elevated central venous pressure is associated with increased mortality and acute kidney injury in critically ill patients: a meta-analysis

Background

The association of central venous pressure (CVP) and mortality and acute kidney injury (AKI) in critically ill adult patients remains unclear. We performed a meta-analysis to determine whether elevated CVP is associated with increased mortality and AKI in critically ill adult patients.

Methods

We searched PubMed and Embase through June 2019 to identify studies that investigated the association between CVP and mortality and/or AKI in critically ill adult patients admitted into the intensive care unit. We calculated the summary odds ratio (OR) and 95% CI using a random-effects model.

Results

Fifteen cohort studies with a broad spectrum of critically ill patients (mainly sepsis) were included. On a dichotomous scale, elevated CVP was associated with an increased risk of mortality (3 studies; 969 participants; OR, 1.65; 95% CI, 1.19–2.29) and AKI (2 studies; 689 participants; OR, 2.09; 95% CI, 1.39–3.14). On a continuous scale, higher CVP was associated with greater risk of mortality (5 studies; 7837 participants; OR, 1.10; 95% CI, 1.03–1.17) and AKI (6 studies; 5446 participants; OR, 1.14; 95% CI, 1.06–1.23). Furthermore, per 1 mmHg increase in CVP increased the odds of AKI by 6% (4 studies; 5150 participants; OR, 1.06; 95% CI, 1.01–1.12). Further analyses restricted to patients with sepsis showed consistent results.

Conclusions

Elevated CVP is associated with an increased risk of mortality and AKI in critically ill adult patients admitted into the intensive care unit.

Trial registration

PROSPERO, CRD42019126381

Changing the syringe pump: A challenging procedure in critically ill patients

INTRODUCTION

In the literature, the change of a syringe pump is described as a dangerous situation, especially in the case of vasoactive drug administration.

METHODS

Different variables have been studied (central venous pressure, pump displacement in relation to the patient position, utilization of a stopcock, or a neutral displacement needle-free connector between the syringe and the infusion tubing) to understand their influence on medication administration in terms of backflow or bolus creation when changing the syringe.

RESULTS

We performed 576 measurements with different combinations. With respect to all the observations, in comparison with "time zero," we found the following differences expressed in microliters: 0 (±1) at the plunger opening; 0 (±3) at the syringe extraction from the pump; 0 (±7) at the syringe disconnection from the infusion tubing; 0 (±11) at the syringe reconnection to the infusion tubing; 1 (±7) at the syringe insertion in the pump; 3 (±23) at the plunger closing; 8 (±33) at the stabilization at the maneuver end.

CONCLUSION

The syringe change can be a very critical moment given different influencing variables. Syringe pump position, displaced higher than the patient level, always generates a medication bolus that is higher at the lowering of the central venous pressure value. The presence of a neutral displacement needle-free connector reduces the incidence of boluses. When the pump is placed at the patient level, the presence of neutral displacement needle-free connector reduces the establishment of boluses, even in a central venous pressure of -5 mmHg simulations.

Reinterpreting Renal Hemodynamics: The Importance of Venous Congestion and Effective Organ Perfusion in Acute Kidney Injury

The significance of effective renal perfusion is relatively underemphasized in the current literature. From a renal standpoint, besides optimizing cardiac output, renal perfusion should be maximized as well. Among the several additional variables of the critically ill, such as intra-abdominal pressure, the presence of venous congestion and elevated central venous pressures, airway pressures generated by mechanical ventilation do affect net renal perfusion. These forces represent both a potential danger and an ongoing opportunity to improve renal outcomes in the critically ill and an opportunity to move beyond the simplified viewpoint of optimizing volume status. Therefore, to optimize nephron-protective therapies, nephrologists and intensive care physicians should be familiar with the concept of net renal perfusion pressure. This review appraises the background literature on renal perfusion pressure, including the initial animal data and historical human studies up to the most current developments in the field, exploring potential avenues to assess and improve renal blood supply.

High positive end expiratory pressure levels affect hemodynamics in elderly patients with hypertension admitted to the intensive care unit: a prospective cohort study

Background

To study the effects of different positive end expiratory pressure (PEEP) on blood pressure and heart function in elderly patients with hypertension.

Methods

Forty elderly patients above 65 years of age treated with mechanical ventilation were divided into two groups: a control group of non-hypertensive subjects (n = 18) and a hypertension group (n = 22) patients with essential hypertension. Changes in blood pressure, central venous pressure (CVP), central venous oxygen saturation (ScvO₂), heart rate, and airway pressure were determined in response to different selected PEEP levels of 0, 2, 4, 6, 8, 10 and 12 cm H₂O under SIMV(PC) + PSV mode throughout the study.

Results

In both groups, the increase in PEEP led to an increase in CVP and airway pressure. When PEEP was above 4 cm H₂O in the hypertension group, a decrease in blood pressure and ScvO₂, and an increase of heart rate were observed. These results indicated that cardiac output significantly decreased.

Conclusion

High levels of PEEP can significantly influence changes in blood pressure and heart function in elderly patients with hypertension.

Trial registration

This trial was retrospectively registered, The Chinese trial registration number is ChiCTR-ROC-17012873. The date of registration is 10-2-2017.

Untreated Relative Hypotension Measured as Perfusion Pressure Deficit During Management of Shock and New-Onset Acute Kidney Injury-A Literature Review

Maintaining an optimal blood pressure (BP) during shock is a fundamental tenet of critical care. Optimal BP targets may be different for different patients. In current practice, too often, uniform BP targets are pursued which may result in inadvertently accepting a degree of untreated relative hypotension, i.e., the deficit between patients' usual premorbid basal BP and the achieved BP, during vasopressor support. Relative hypotension is a common but an under-recognized and an under-treated sign among patients with potential shock state. From a physiological perspective, any relative reduction in the net perfusion pressure across an organ (e.g., renal) vasculature has a potential to overwhelm autoregulatory mechanisms, which are already under stress during shock. Such perfusion pressure deficit may consequently impact organs' ability to function or recover from an injured state. This review discusses such pathophysiologic mechanisms in detail with a particular focus on the risk of new-onset acute kidney injury (AKI). To review current literature, databases of Medline, Embase, and Google scholar were searched to retrieve articles that either adjusted BP targets based on patients' premorbid BP levels or considered relative hypotension as an exposure endpoint and assessed its association with clinical outcomes among acutely ill patients. There were no randomized controlled trials. Only seven studies could be identified and these were reviewed in detail. These studies indicated a significant association between the degree of relative hypotension that was inadvertently accepted in real-world practice and new-onset organ dysfunction or subsequent AKI. However, this is not a high-quality evidence. Therefore, well-designed randomized controlled trials are needed to evaluate whether adoption of individualized BP targets, which are initially guided by patient's premorbid basal BP and then tailored according to clinical response, is superior to conventional BP targets for vasopressor therapy, particularly among patients with vasodilatory shock states.

Fluid therapy in non-septic, refractory acute decompensated heart failure patients - The cautious role of central venous pressure

PURPOSE

Fluid therapy in congestive acute decompensated heart failure (ADHF) patients might be inappropriate and worsening the prognosis. The aim of our study was to analyze the effect of fluid administration on mortality in non-septic, ADHF patients with reduced ejection fraction.

MATERIAL AND METHODS

We analyzed 41 ADHF consecutive 'cold-wet' patients (mean age 69.3 ± 14.9 years, 27 men, LVEF 22.8 ± 11.1%, lactates 2.2 ± 1.6 mmol/L) without sepsis. At admission central venous pressure (CVP) was measured (17.6 ± 7.2 cm H₂O), and ultrasound examination of inferior vena cava (IVC) was performed (IVC min. 18.6 ± 7.3 mm and IVC max. 24.6 ± 4.3 mm). Moreover, the groups were compared (survivors vs. non-survivors as well as 1st and 4th quartile of CVP).

RESULTS

Altogether 17 (41%) patients died: 16 (39%) during a mean of 11.2 ± 7.8 days of hospitalization and 1 during a 30-day follow up. Patients in the lowest CVP quartile (<13 cm H₂O) had significantly worse in-hospital survival as compared to patients in the highest quartile (>24 cm H₂O), P = 0.012. Higher intravenous fluid volumes within the first 24 h were infused in patients in the lowest CVP quartile as compared to the highest CVP quartile (1791.7 ± 1357.8 mL vs. 754.5 ± 631.4 mL, P = 0.046). Moreover, more fluids were infused in a group of patients who died during a hospital stay and at 30-day follow up (1362.8 ± 752.7 mL vs. 722.7 ± 1046.5 mL, P = 0.004; 1348.8 ± 731.0 mL vs. 703.6 ± 1068.4 mL, P = 0.002, respectively).

CONCLUSIONS

CVP-guided intravenous fluid therapy is a common practice which in high risk ADHF 'cold-wet' patients might be harmful and should rather be avoided. Lower CVP seems to be related with worse prognosis.

Renal failure in critically ill patients, beware of applying (central venous) pressure on the kidney

The central venous pressure (CVP) is traditionally used as a surrogate of intravascular volume. CVP measurements therefore are often applied at the bedside to guide fluid administration in postoperative and critically ill patients. Pursuing high CVP levels has recently been challenged. A high CVP might impede venous return to the heart and disturb microcirculatory blood flow which may cause tissue congestion and organ failure. By imposing an increased "afterload" on the kidney, an elevated CVP will particularly harm kidney hemodynamics and promote acute kidney injury (AKI) even in the absence of volume overload. Maintaining the lowest possible CVP should become routine to prevent and treat AKI, especially when associated with septic shock, cardiac surgery, mechanical ventilation, and intra-abdominal hypertension.

Prediction of fluid responsiveness in ventilated patients

Fluid administration is the first-line therapy in patients with acute circulatory failure. The main goal of fluid administration is to increase the cardiac output and ultimately the oxygen delivery. Nevertheless, the decision to administer fluids or not should be carefully considered, since half of critically ill patients are fluid unresponsive, and the deleterious effects of fluid overload clearly documented. Thus, except at the initial phase of hypovolemic or septic shock, where hypovolemia is constant and most of the patients responsive to the initial fluid resuscitation, it is of importance to test fluid responsiveness before administering fluids in critically ill patients. The static markers of cardiac preload cannot reliably predict fluid responsiveness, although they have been used for decades. To address this issue, some dynamic tests have been developed over the past years. All these tests consist in measuring the changes in cardiac output in response to the transient changes in cardiac preload that they induced. Most of these tests are based on the heart-lung interactions. The pulse pressure or stroke volume respiratory variations were first described, following by the respiratory variations of the vena cava diameter or of the internal jugular vein diameter. Nevertheless, all these tests are reliable only under strict conditions limiting their use in many clinical situations. Other tests such as passive leg raising or end-expiratory occlusion act as an internal volume challenge. To reliably predict fluid responsiveness, physicians must choose among these different dynamic tests, depending on their respective limitations and on the cardiac output monitoring technique which is used. In this review, we will summarize the most recent findings regarding the prediction of fluid responsiveness in ventilated patients.

Elevated central venous pressure is associated with increased mortality in pediatric septic shock patients

BACKGROUND

Central venous pressure (CVP) is an important factor affecting capillary blood flow, and it is associated with poor outcomes in adult septic shock patients. However, whether a similar association exists in pediatric patients remains unclear.

METHODS

We retrospectively analyzed data from patients admitted to our pediatric intensive care unit (PICU) between February 2009 and July 2015. Patients were divided into two groups-survivors and nonsurvivors-according to 28-day mortality. The associations between (a) mortality and CVP at 6, 24, 48, and 72 h after initiating treatment for established septic shock was analyzed and (b) initial serum lactic acid levels and 6-h CVP.

RESULTS

Two hundred twenty-six patients were included in this study, and the mortality rate was 29.6% (67 deaths, nonsurvivor group). Initial serum lactic acid levels, Pediatric Risk of Mortality (PRISM) III score, and Vasoactive-Inotropic Score (VIS) within 24 h after PICU admission were significantly higher in the nonsurvivors than in survivors (1.3 [0.9, 2.4] vs. 3.9 [1.6, 8.0] mmol/l, 11.0 [7.0, 15.0] vs. 17.0 [10.0, 21.5], 12.0 [7.0, 25.0] vs. 22.5 [8.0, 55.0], respectively with p-values < 0.001, < 0.001, and 0.009, respectively). In addition, compared to survivors, a greater percentage of nonsurvivors required mechanical ventilation (92.5% vs. 51.6%, p <  0.001) and showed a greater extent of fluid overload at 48 h after admission (3.9% vs. 1.9%, p = 0.006), along with higher 6-h CVP (10.0 [7.0, 16.0] vs. 8.0 [5.0, 11.0] mmHg, p <  0.001). Patient survival according to levels of CVP (CVP < 8 mmHg, CVP 8-12 mmHg, or CVP > 12 mmHg) showed that the CVP > 12-mmHg group had significantly greater mortality rates (50.0%, p = 0.002) than the other groups (21.3% and 27.5%). Furthermore, multivariate analysis identified significant associations of CVP > 12 mmHg, serum lactic acid levels, and the need for mechanical ventilation with mortality (OR: 2.74, 1.30, and 12.51, respectively; 95% CI: 1.11-6.72, 1.12-1.50, and 4.12-37.96, respectively).

CONCLUSIONS

Elevated CVP is an independent risk factor for mortality in pediatric septic shock patients.

Does Fluid Type and Amount Affect Kidney Function in Critical Illness?

Acute kidney injury (AKI) is common, although commonly used clinical diagnostic markers are imperfect. Intravenous fluid administration remains a cornerstone of therapy worldwide, but there is minimal evidence of efficacy for the use of fluid bolus therapy outside of specific circumstances, and emerging evidence associates fluid accumulation with worse renal outcomes and even increased mortality among critically ill patients. Artificial colloid solutions have been associated with harm, and chloride-rich solutions may adversely affect renal function. Large trials to provide guidance regarding the optimal fluid choices to prevent or ameliorate AKI, and promote renal recovery, are urgently required.