Assessment of venous pressure by compression sonography of the internal jugular vein during 3 days of bed rest.

Compression sonography has been proposed as a method for non-invasive measurement of venous pressures during spaceflight, but initial reports of venous pressure measured by compression ultrasound conflict with prior reports of invasively measured central venous pressure (CVP). The aim of this study is to determine the agreement of compression sonography of the internal jugular vein (IJVP) with invasive measures of CVP over a range of pressures relevant to microgravity exposure. Ten healthy volunteers (18-55 years, five female) completed two 3-day sessions of supine bed rest to simulate microgravity. IJVP and CVP were measured in the seated position, and in the supine position throughout 3 days of bed rest. The range of CVP recorded was in line with previous reports of CVP during changes in posture on Earth and in microgravity. The correlation between IJVP and CVP was poor when measured during spontaneous breathing (r = 0.29; R2  = 0.09; P = 0.0002; standard error of the estimate (SEE) = 3.0 mmHg) or end-expiration CVP (CVPEE ; r = 0.19; R2  = 0.04; P = 0.121; SEE = 3.0 mmHg). There was a modest correlation between the change in CVP and the change in IJVP for both spontaneous ΔCVP (r = 0.49; R2  = 0.24; P < 0.0001) and ΔCVPEE (r = 0.58; R2  = 0.34; P < 0.0001). Bland-Altman analysis of IJVP revealed a large positive bias compared to spontaneous breathing CVP (3.6 mmHg; SD = 4.0; CV = 85%; P < 0.0001) and CVPEE (3.6 mmHg; SD = 4.2; CV = 84%; P < 0.0001). Assessment of absolute IJVP via compression sonography correlated poorly with direct measurements of CVP by invasive catheterization over a range of venous pressures that are physiologically relevant to spaceflight. However, compression sonography showed modest utility for tracking changes in venous pressure over time. NEW FINDINGS: What is the central question of this study? Compression sonography has been proposed as a novel method for non-invasive measurement of venous pressures during spaceflight. However, the accuracy has not yet been confirmed in the range of CVP experienced by astronauts during spaceflight. What is the main finding and its importance? Our data show that compression sonography of the internal jugular vein correlates poorly with direct measurement of central venous pressures in a range that is physiologically relevant to spaceflight. However, compression sonography showed modest utility for tracking changes in venous pressure over time.

Portable ultrasound assessment of jugular venous pressure is an accurate method for estimating volaemic status in patients with cardiac disease.

PURPOSE: The objective of this study was to determine whether ultrasound-measured jugular venous pressure (U-JVP) could accurately estimate central venous pressure (CVP). METHODS: This prospective, diagnostic, single-centre study was performed at the Cardiac Intensive Care Unit of the Northern General Hospital, Sheffield, UK. Post-cardiac surgery patients were recruited from January to May 2019. The investigators were blinded to the central venous pressure when measuring the jugular venous pressure. U-JVP and direct CVP were measured simultaneously. Measurements were taken whilst the patient was ventilated and then repeated when the patient was extubated, providing non-ventilated readings. RESULTS: One-hundred and fourteen consecutive participants with a male predominance of 71% and mean age of 65 ± 12 years were included in the analysis. Bland-Altman plots revealed that U-JVP marginally overestimated CVP by 0.91 mmHg (95% limits of agreement were -2.936 to 4.754) in ventilated patients and by 0.11 mmHg (95% limits of agreement between -2.481 and 2.695) in non-ventilated patients. Reasonable sensitivity and specificity of ultrasound-measured jugular venous pressure was achieved for low and high central venous pressure in both ventilated and non-ventilated patients. CONCLUSION: U-JVP accurately estimates cardiac filling pressure and fluid status in patients after cardiac surgery, irrespective of their ventilatory status. Jugular venous pressure measurement by insonation is a reliable technique that can be taught to medical students and other health professionals to non-invasively estimate central venous pressure and may be useful for assessment of volaemic status in patients with heart failure. TRIAL REGISTRATION: ClinicalTrials.gov public (identifier NCT03815188).

Inferior Vena Cava Collapsibility Index and Central Venous Pressure for Fluid Assessment in the Critically Ill Patient.

OBJECTIVE: To determine the correlation of sonographic evaluation of inferior vena cava diameter and its collapsibility index with central venous pressure in both spontaneously breathing and mechanically ventilated patients in surgical ICU.    Study Design: Cross-sectional study. PLACE AND DURATION OF STUDY: Surgical ICU, Lahore General Hospital from November 2020 to May 2021. METHODOLOGY: All patients above 18 years of age, who had central venous catheter placed, were included in the study. Patients with raised abdominal pressure, pregnancy, morbid obesity, heart diseases, and those unable to lie in supine position, were excluded. For inferior vena cava (IVC) measurement, IVC was visualised using curvilinear probe of ultrasound machine. Minimum and maximum diameters of inferior vena cava were calculated in every respiratory phase.  IVC collapsibility index was expressed in percentage. Central venous pressure (CVP) was recorded soon after IVC measurement, using manometer. RESULTS: Total number of patients was 126. A significant correlation was seen between IVC measurements (inferior vena cava diameters and the collapsibility index) and CVP, (p<0.001), but the regression coefficients were less in patients who were mechanically ventilated (r=0.779 for IVC maximum diameter and -0.725 for collapsibility index) than the   patients who were breathing spontaneously (r=0.850 for IVC maximum diameter and   -0.899 for collapsibility index) Conclusion: Evaluation of IVC diameter and its collapsibility index is an easy and non-invasive   method to evaluate intravascular volume   status of critically ill patients. Its use is more helpful in patients who are spontaneously breathing than those who are mechanically ventilated. Key Words: Central venous pressure, Fluid status, Inferior vena cava diameter.

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.

Reducing intracranial pressure by reducing central venous pressure: assessment of potential countermeasures to spaceflight-associated neuro-ocular syndrome.

Spaceflight-associated neuro-ocular syndrome (SANS) involves unilateral or bilateral optic disc edema, widening of the optic nerve sheath, and posterior globe flattening. Owing to posterior globe flattening, it is hypothesized that microgravity causes a disproportionate change in intracranial pressure (ICP) relative to intraocular pressure. Countermeasures capable of reducing ICP include thigh cuffs and breathing against inspiratory resistance. Owing to the coupling of central venous pressure (CVP) and intracranial pressure, we hypothesized that both ICP and CVP will be reduced during both countermeasures. In four male participants (32 ± 13 yr) who were previously implanted with Ommaya reservoirs for treatment of unrelated clinical conditions, ICP was measured invasively through these ports. Subjects were healthy at the time of testing. CVP was measured invasively by a peripherally inserted central catheter. Participants breathed through an impedance threshold device (ITD, -7 cmH2O) to generate negative intrathoracic pressure for 5 min, and subsequently, wore bilateral thigh cuffs inflated to 30 mmHg for 2 min. Breathing through an ITD reduced both CVP (6 ± 2 vs. 3 ± 1 mmHg; P = 0.02) and ICP (16 ± 3 vs. 12 ± 1 mmHg; P = 0.04) compared to baseline, a result that was not observed during the free breathing condition (CVP, 6 ± 2 vs. 6 ± 2 mmHg, P = 0.87; ICP, 15 ± 3 vs. 15 ± 4 mmHg, P = 0.68). Inflation of the thigh cuffs to 30 mmHg caused no meaningful reduction in CVP in all four individuals (5 ± 4 vs. 5 ± 4 mmHg; P = 0.1), coincident with minimal reduction in ICP (15 ± 3 vs. 14 ± 4 mmHg; P = 0.13). The application of inspiratory resistance breathing resulted in reductions in both ICP and CVP, likely due to intrathoracic unloading.NEW & NOTEWORTHY Spaceflight causes pathological changes in the eye that may be due to the absence of gravitational unloading of intracranial pressure (ICP) under microgravity conditions commonly referred to as spaceflight-associated neuro-ocular syndrome (SANS), whereby countermeasures aimed at lowering ICP are necessary. These data show that impedance threshold breathing acutely reduces ICP via a reduction in central venous pressure (CVP). Whereas, acute thigh cuff inflation, a popular known spaceflight-associated countermeasure, had little effect on ICP and CVP.

Pretransplantation and Post-Transplantation Liver Disease Assessment in Adolescents Undergoing Isolated Heart Transplantation for Fontan Failure.

OBJECTIVE: To describe the assessment of Fontan-associated liver disease and determine the clinical and imaging measures that may identify hepatic morbidity risk in isolated heart transplantation candidates and trend those measures post-isolated heart transplantation. STUDY DESIGN: Retrospective analysis of pre-isolated heart transplantation and post-isolated heart transplantation Fontan-associated liver disease (FALD) status using blood tests, magnetic resonance imaging (MRI), and liver biopsy analysis within 6 months before isolated heart transplantation and 12 months after isolated heart transplantation in 9 consecutive patients with Fontan. Pre- and post-isolated heart transplantation standard laboratory values; varices, ascites, splenomegaly, thrombocytopenia (VAST) score; Fontan liver MRI score; liver biopsy scores; Model for End-stage Liver Disease (MELD); MELD excluding the International Normalized Ratio (MELD-XI); AST to platelet ratio index, and cardiac catheterization data were compared. RESULTS: Pretransplantation maximum MELD and MELD-XI was 15 and 16, respectively. Central venous pressures and VAST scores decreased significantly post-transplantation. In 5 paired studies, Fontan liver MRI score maximum was 10 pretransplantation and decreased significantly post-transplantation. Arterially enhancing nodules on MRI persisted in 2 patients post-transplantation. Pretransplantation and post-transplantation liver biopsy scores did not differ in 4 paired biopsy specimens. CONCLUSIONS: Patients with FALD and MELD <15, MELD-XI <16, Fontan liver MRI score <10, and VAST score ≤2 can have successful short-term isolated heart transplantation outcomes. Liver MRI and VAST scores improved post-transplantation. Post-transplantation liver biopsy scores did not change significantly. Pretransplantation liver biopsy demonstrating fibrosis alone should not exclude consideration of isolated heart transplantation. The persistence of hepatic vascular remodeling and fibrosis post-isolated heart transplantation suggests that continued surveillance for hepatic complications post-transplantation for patients with Fontan is reasonable.

Central venous pressure estimation from ultrasound assessment of the jugular venous pulse.

OBJECTIVES: Acquiring central venous pressure (CVP), an important clinical parameter, requires an invasive procedure, which poses risk to patients. The aim of the study was to develop a non-invasive methodology for determining mean-CVP from ultrasound assessment of the jugular venous pulse. METHODS: In thirty-four adult patients (age = 60 ± 12 years; 10 males), CVP was measured using a central venous catheter, with internal jugular vein (IJV) cross-sectional area (CSA) variation along the cardiac beat acquired using ultrasound. The resultant CVP and IJV-CSA signals were synchronized with electrocardiogram (ECG) signals acquired from the patients. Autocorrelation signals were derived from the IJV-CSA signals using algorithms in R (open-source statistical software). The correlation r-values for successive lag intervals were extracted and used to build a linear regression model in which mean-CVP was the response variable and the lagging autocorrelation r-values and mean IJV-CSA, were the predictor variables. The optimum model was identified using the minimum AIC value and validated using 10-fold cross-validation. RESULTS: While the CVP and IJV-CSA signals were poorly correlated (mean r = -0.018, SD = 0.357) due to the IJV-CSA signal lagging behind the CVP signal, their autocorrelation counterparts were highly positively correlated (mean r = 0.725, SD = 0.215). Using the lagging autocorrelation r-values as predictors, mean-CVP was predicted with reasonable accuracy (r2 = 0.612), with a mean-absolute-error of 1.455 cmH2O, which rose to 2.436 cmH2O when cross-validation was performed. CONCLUSIONS: Mean-CVP can be estimated non-invasively by using the lagged autocorrelation r-values of the IJV-CSA signal. This new methodology may have considerable potential as a clinical monitoring and diagnostic tool.

Variation in Fluid and Vasopressor Use in Shock With and Without Physiologic Assessment: A Multicenter Observational Study.

OBJECTIVES: To characterize the association between the use of physiologic assessment (central venous pressure, pulmonary artery occlusion pressure, stroke volume variation, pulse pressure variation, passive leg raise test, and critical care ultrasound) with fluid and vasopressor administration 24 hours after shock onset and with in-hospital mortality. DESIGN: Multicenter prospective cohort study between September 2017 and February 2018. SETTINGS: Thirty-four hospitals in the United States and Jordan. PATIENTS: Consecutive adult patients requiring admission to the ICU with systolic blood pressure less than or equal to 90 mm Hg, mean arterial blood pressure less than or equal to 65 mm Hg, or need for vasopressor. INTERVENTIONS: None. MEASUREMENT AND MAIN RESULTS: Of 1,639 patients enrolled, 39% had physiologic assessments. Use of physiologic assessment was not associated with cumulative fluid administered within 24 hours of shock onset, after accounting for baseline characteristics, etiology and location of shock, ICU types, Acute Physiology and Chronic Health Evaluation III, and hospital (beta coefficient, 0.04; 95% CI, -0.07 to 0.15). In multivariate analysis, the use of physiologic assessment was associated with a higher likelihood of vasopressor use (adjusted odds ratio, 1.98; 95% CI, 1.45-2.71) and higher 24-hour cumulative vasopressor dosing as norepinephrine equivalent (beta coefficient, 0.37; 95% CI, 0.19-0.55). The use of vasopressor was associated with increased odds of in-hospital mortality (adjusted odds ratio, 1.88; 95% CI, 1.27-2.78). In-hospital mortality was not associated with the use of physiologic assessment (adjusted odds ratio, 0.86; 95% CI, 0.63-1.18). CONCLUSIONS: The use of physiologic assessment in the 24 hours after shock onset is associated with increased use of vasopressor but not with fluid administration.

Non-invasive assessment of central venous pressure in heart failure: a systematic prospective comparison of echocardiography and Swan-Ganz catheter.

Assessing hemodynamics, especially central venous pressure (CVP), is essential in heart failure (HF). Right heart catheterization (RHC) is the gold-standard, but non-invasive methods are also needed. However, the role of 2-dimensional echocardiography (2DE) remains uncertain, and 3-dimensional echocardiography (3DE) is not always available. This study investigated standardized and breathing-corrected assessment of inferior vena cava (IVC) volume using echocardiography (2DE and 3DE) versus CVP determined invasively using RHC. Sixty consecutive HF patients were included (82% male, age 54 ± 11 years, New York Heart Association class 2.23 ± 0.8, ejection fraction 46 ± 18.4%, brain natriuretic peptide 696.93 ± 773.53 pg/mL). All patients underwent Swan-Ganz RHC followed by 2DE and 3DE, and IVC volume assessment. On 2DE, mean IVC size was 18.3 ± 5.5 mm and 13.8 ± 6 mm in the largest deflection and shortest distention, respectively. Mean CVP from RHC was 9.3 ± 5.3 mmHg. Neither 2DE nor 3DE showed acceptable correlation with invasively measured CVP; IVC volume acquisition showed optimal correlation with RHC CVP (0.64; 95% confidence interval 0.46-0.77), with better correlation when mitral valve early diastole E wave and right ventricular end-diastolic diameter were added. Using a CVP cut-point of 10 mmHg, receiver operating characteristic curve showed true positivity (specificity) of 0.90 and sensitivity of 62% for predicting CVP. A validation study confirmed these findings and verified the high predictive value of IVC volume assessment. Neither 2DE nor 3DE alone can reliably mirror CVP, but IVC volume acquisition using echocardiography allows non-invasive and adequate approximation of CVP. Correlation with invasively measured pressure was strongest when CVP is > 10 mmHg.

Bedside hand vein inspection for noninvasive central venous pressure assessment.

Rapid estimates of the central venous pressure (CVP) can be helpful to administer early fluid therapy or to manage cardiac preload in intensive care units, operating rooms or emergency rooms in order to start and monitor an adequate medical therapy. Invasive CVP measurements have inherent and non-negligible complication rates as well as great expenditures. Several noninvasive methods of CVP measurements, like ultrasound-guided techniques, are available, but require trained skills and special equipment which might not be at hand in all situations. Our purpose was to evaluate the feasibility and accuracy of CVP estimates assessed upon the height of hand veins collapse (HVC) using invasively measured CVP as the gold standard. The HVC was determined by slowly lifting the patient's hand while watching the dorsal hand veins to collapse. The vertical distance from the dorsal hand to a transducer air zero port was noted and converted to mmHg. The observer was blinded to the simultaneously measured CVP values, which were categorized as low (<7 mmHg), normal (7-12 mmHg) and high (>12 mmHg). Measurements were performed in 82 patients who had a median [IQR] age of 67 [60;74]. Median CVP was 12 [8;15] mmHg and the median absolute difference between the measured HVC and CVP was 4 [2;7] mmHg. The Spearman correlation coefficient between CVP and HVC was 0.55, 95%-CI [0.35;0.69]. Overall CVP categorization was correct in 45% of the cases. HVC had a sensitivity of 92% for a low CVP with a negative predictive value of 98%. A high HVC had a sensitivity of 29% but a high specificity of 94% for a high CVP. The overall performance of observing the hand vein collapse to estimate CVP was only moderate in the intensive care setting. However, the median difference to the CVP was low and HVC identifies a low CVP with a high sensitivity and excellent negative predictive value.

[Choice of assessment time after fluid challenge in patients with septic shock].

OBJECTIVE: To explore the short-term hemodynamic change of fluid challenge (FC) with crystalloid or colloid and define fluid responsiveness at the optimal time in patients with septic shock. METHODS: A prospective observational study was conducted. Septic shock patients monitored with pulmonary catheters admitted to medical intensive care unit (ICU) of the Peking Union Medical College Hospital from July 2016 to December 2018 were enrolled. All included patients received FC and were divided into two groups according to the type of fluid used, i.e. crystalloid group (normal saline for 500 mL) and colloid group (4% succinyl gelatin for 500 mL). The choice of fluid type was decided by the attending physician. Hemodynamic variables were measured at baseline, and 0 (immediately), 10, 30, 45, 60, 90, 120 minutes after FC, included cardiac index (CI), heart rate (HR), mean artery pressure (MAP), central venous pressure (CVP) and pulmonary arterial wedge pressure (PAWP). Fluid responsiveness was defined as CI increased by more than 10% after FC. The data were analyzed by repeated measurements of variance between the two groups as well as responders and nonresponders. RESULTS: Forty patients were included, 20 cases each in colloid group and crystalloid group; of whom 26 were fluid responders with 12 of colloid group and 14 of crystalloid group. Of the 14 nonresponders, 8 were of colloid group and 6 of crystalloid group. (1) Compared with before FC, CI (mL×s-1×m-2) was significantly increased in crystalloid and colloid groups after FC (71.7±16.7 vs. 65.0±16.7, 68.3±25.0 vs. 63.3±23.3, both P < 0.05). In the colloid group, volume expansion increased the CI to maximum (76.7±18.3) at 30 minutes after FC, at 120 minutes after FC, a significantly higher CI (70.0±16.7) was also observed (P < 0.05), an increased in CI ≥ 10% was observed at 60 minutes after FC. In the crystalloid group, CI was increased to maximum at 10 minutes (73.3±28.3) and decreased to baseline at 60 minutes, an increased in CI ≥ 10% was also observed at 10 minutes after FC. In addition, there was no significant difference in CI changes between colloidal group and crystalloid group at different time points after FC. (2) CI did not change over time in nonresponders groups, whereas in responders CI increased parallelly to that in both crystalloid and colloid groups over time. However, an increased in CI ≥ 10% was observed through the 120 minutes after FC in responders of colloid group compared with that of at 30 minutes after FC in crystalloid group. There was significant difference in CI changes between colloidal group and crystalloid group at 30, 45, 60, 90 minutes after FC (mL×s-1×m-2: 18.3±3.3 vs. 8.3±1.7, 18.3±3.3 vs. 5.0±1.7, 13.3±1.7 vs. 3.3±1.7, 11.7±3.3 vs. 3.3±1.7, all P < 0.05). (3) The maximal values of CVP and PAWP were observed at the end of FC. In colloid group, both the two variables were notably higher than that before FC over 120 minutes compared with that of only at 10 minutes in crystalloid group. The MAP in colloid increased to maximum immediately at the end of FC and decreased to baseline at 45 minutes, however, the MAP in crystalloid group and HR of both groups showed no differences over 120 minutes. CONCLUSIONS: Hemodynamic changes were significantly different between crystalloid and colloid after FC in patients with septic shock. Therefore, the timing of fluid responsiveness assessment should be different individually. The assessment time of colloid group may be prolonged to 30 minutes after FC while that of crystal group can be at 10 minute after FC.

Usefulness of Red Blood Cell Distribution Width in the Assessment of Hemodynamics After Tetralogy of Fallot Repair.

BACKGROUND: There are no reports on the effect of red blood cell distribution width (RDW) in surgical repair of tetralogy of Fallot (ToF). Methods and Results: A total of 50 patients who underwent cardiac catheterization after surgical repair of ToF were retrospectively assessed. RDW was positively correlated with the ratio of right ventricular pressure to left ventricular pressure (RVP/LVP; P<0.0001, r2=0.57). Patients with elevated RDW had a higher RVP/LVP than those with a normal RDW (P<0.0001). Also, elevated RDW was related to elevated central venous pressure (P<0.0001), decreased mixed venous oxygen saturation (P<0.0001), greater pulmonary stenosis (P=0.003) and severe pulmonary regurgitation on echocardiography (P<0.0001), a higher rate of residual ventricular septal defect leak (P=0.004) and higher reoperation rate (P=0.009). Of the 7 patients who underwent reoperation, 6 had decrease in RDW after reoperation (P=0.012). On multivariable regression analysis, RDW was the strongest indicator of higher RVP/LVP. CONCLUSIONS: For the first time, RDW has been shown to be a strong indicator for assessing the hemodynamics and risk of later reoperation after surgical repair of ToF.

Performance of Noninvasive Assessment in the Diagnosis of Right Heart Failure After Left Ventricular Assist Device.

Right heart failure (RHF) after left ventricular assist device (LVAD) is associated with poor outcomes. Interagency Registry for Mechanically Assisted Circulatory Support (Intermacs) defines RHF as elevated right atrial pressure (RAP) plus venous congestion. The purpose of this study was to examine the diagnostic performance of the noninvasive Intermacs criteria using RAP as the gold standard. We analyzed 108 patients with LVAD who underwent 341 right heart catheterizations (RHC) between January 1, 2006, and December 31, 2013. Physical exam, echocardiography, and laboratory data at the time of RHC were collected. Conventional two-by-two tables were used and missing data were excluded. The noninvasive Intermacs definition of RHF is 32% sensitive (95% cardiac index (CI), 0.21-0.44) and 97% specific (95% CI, 0.95-0.99) for identifying elevated RAP. Clinical assessment failed to identify two-thirds of LVAD patients with RAP > 16 mm Hg. More than half of patients with elevated RAP did not have venous congestion, which may represent a physiologic opportunity to mitigate the progression of disease before end-organ damage occurs. One-quarter of patients who met the noninvasive definition of RHF did not actually have elevated RAP, potentially exposing patients to unnecessary therapies. In practice, if any component of the Intermacs definition is present or equivocal, our data suggest RHC is warranted to establish the diagnosis.

Assessment of central hemodynamic effects of phenylephrine: an animal experiment.

Phenylephrine is an α1-adrenergic receptor agonist widely used to treat perioperative hypotension. Its other hemodynamic effects, in particular on preload and contractility, remain controversial. We, therefore, investigated the effect of continuously applied phenylephrine on central hemodynamics in eight mechanically ventilated domestic pigs. Mean arterial pressure (MAP) was increased in steps by 50%, and 100% using phenylephrine. Besides stroke volume (SV), cardiac output (CO), and MAP, mean systemic vascular resistance (SVR) and dynamic arterial elastance (Eadyn) were assessed for characterization of afterload. Changes in preload were assessed by central venous pressure (CVP), global end-diastolic volume (GEDV), mean systemic filling pressure analog (Pmsfa), pulse pressure variation (PPV), and stroke volume variation (SVV). Further, cardiac function index (CFI), global ejection fraction and dPmax were measured as markers of preload dependent contractility. MAP, SV, and CO significantly increased following both interventions, as did SVR. In contrast, Eadyn did not show significant changes. Although the volumetric preload variable GEDV increased after the first step of phenylephrine, this was not reflected by significant changes in CVP or Pmsfa. CFI and dPmax significantly increased after both steps. Phenylephrine does not only affect cardiac afterload, but also increases effective preload. In contrast to CVP and Pmsfa, this effect can be monitored by GEDV. Further, phenylephrine affects contractility.

Remote Photoplethysmographic Assessment of the Peripheral Circulation in Critical Care Patients Recovering From Cardiac Surgery.

PURPOSE: Camera-based photoplethysmography (cbPPG) remotely detects the volume pulse of cardiac ejection in the peripheral circulation. The cbPPG signal is sourced from the cutaneous microcirculation, yields a 2-dimensional intensity map, and is therefore an interesting monitoring technique. In this study, we investigated whether cbPPG is in general sufficiently sensitive to discern hemodynamic conditions. METHODS: cbPPG recordings of 70 patients recovering from cardiac surgery were analyzed. Photoplethysmograms were processed offline and the optical pulse power (OPP) of cardiac ejection was calculated. Hemodynamic data, image intensity, and patient movements were recorded synchronously. The effects of hemodynamic parameters and measurement conditions on the patient's individual OPP variability and their actual OPP values were calculated in mixed-effects regression models. RESULTS: Mean arterial pressure (MAP), pulse pressure (PP), heart rate (HR), and central venous pressure (CVP) significantly explained the individual OPP variability. PP had the highest explanatory power (19.9%). Averaged OPP significantly increased with PP and MAP (P < 0.001, respectively) and decreased with higher HR (P = 0.024). CVP had a 2-directional, nonsignificant effect on averaged OPP. Image intensity and patient movements did significantly affect OPP. After adjustment for hemodynamic covariables and measurement conditions, the effect of PP and HR remained unchanged, whereas that of MAP vanished. CONCLUSION: cbPPG is sensitive to hemodynamic parameters in critical care patients. It is a potential application for monitoring the peripheral circulation. Its value in a clinical setting has to be determined.

[The clinical significance of microcirculation and oxygen metabolism evaluation in acute kidney injury assessment in patients with septic shock after resuscitation].

Objective: To evaluate the value of microcirculation and oxygen metabolism evaluation (MicrOME) in acute kidney injury(AKI) evaluation in patients with septic shock after resuscitation. Methods: Consecutive patients with septic shock after resuscitation and mechanical ventilation were enrolled from October 2016 to February 2017 in ICU at Peking Union Medical College Hospital.Patients were divided into 3 groups based on 10 min transcutaneous oxygen challenge test transcutaneous partial pressure of oxygen(PtcO(2))and venoarterial pressure of carbon dioxide difference (Pv-aCO(2)) /arteriovenous O(2) content difference (Ca-vO(2)) by blood gas analysis, i.e. group A [ΔPtcO(2)>66 mmHg(1 mmHg=0.133 kPa) and Pv-aCO(2)/Ca-vO(2)≤1.23], group B (ΔPtcO(2)≤66 mmHg), group C (ΔPtcO(2)>66 mmHg and Pv-aCO(2)/Ca-vO(2)>1.23). Heart rate,mean arterial pressure,central venous pressure,noradrenaline dose,lactate,Pv-aCO(2),Ca-vO(2), lactate clearance, central venous oxygen saturation(ScvO(2)) and liquid equilibrium were assessed after resuscitation.AKI staging based on Kidney Disease Global Improving Outcomes (KDIGO) clinical practice guideline was analyzed. The predictive value of lactate, ScvO(2), Pv-aCO(2)/Ca-vO(2) to progression of AKI after resuscitation was determined using receiver operating characteristic(ROC)curve analysis. Results: A total of 49 septic shock patients were enrolled including 30 males and 19 females with mean age of (61.10±17.10)years old.There were 19 patients in group A,21 patients in group B, and 9 patients in group C. Acute physiology and chronic health evaluation Ⅱ score was 20.92±7.19 and sequential organ failure assessment score 12.02±3.28. There were 4 patients with AKI and 1 progressed in group A, 11 patients with AKI and 2 progressed in group B, 6 patients with AKI and 4 progressed in group C. The cutoff value of Pv-aCO(2)/Ca-vO(2) was equal or more than 2.20 for predicting progression of AKI, resulting in a sensitivity of 85.7% and a specificity of 73.8%. Conclusion: MicrOME is a significant parameter to predict the progression of AKI in patients with septic shock after resuscitation. Pv-aCO(2)/Ca-vO(2) is also a good predictive factor.

Ultrasonographic assessment of the internal jugular vein for the estimation of central venous pressure in hemodialysis patients: A preliminary study.

PURPOSE: To investigate a new noninvasive method to assess central venous pressure (CVP) in hemodialysis patients, based on the ultrasonographic measurement of the collapsing point of the internal jugular vein (CVPni). MATERIALS AND METHODS: In this preliminary, noninterventional, single center study, we enrolled 22 dialyzed patients with an indwelling jugular catheter. CVPni was compared to the gold-standard invasive measurement of CVP using the central venous catheter (CVPi). Agreement between CVPi and CVPni was assessed by Bland and Altman Method. Correlation was assessed by linear regression. RESULTS: A strong correlation was observed between CVPi and CVPni (OR = 3.47 [2.96; 4.07], P < .0001). For overloaded patients, the area under the curve for the operating characteristic curve was 0.971 (IC95: 0.915; 1.000). For under-loaded patients, area under the curve was 0.971 (IC95: 0.917; 1.000). The mean bias between intra-individual CVPi and CVPni measures was 0.57 cm H2 O (SD: 3.1 cm H2 O). CONCLUSION: CVPni appears as a noninvasive and reliable technique. Further studies are required to confirm these results and to assess the direct clinical impact of this new method.

Assessment of renal perfusion impairment in a rat model of acute renal congestion using contrast-enhanced ultrasonography.

Renal congestion is caused by elevated central venous pressure (CVP), and decreases glomerular filtration in patients with congestive heart failure. Since real-time contrast-enhanced ultrasonography (CEUS) using microbubble-based contrast agents can visualize the perfused microvascular bed, we sought to evaluate the impairment of renal perfusion during acute renal congestion with CEUS. In Wister rats, CEUS of kidney was performed with the direct monitoring of CVP and intra-renal pressure (IRP). When CVP was elevated to 10 and 15 mmHg after the bolus injection of normal saline via the femoral vein, peak intensity (PI, dB) and time to PI (TTP) in the renal cortex and medulla were compared with control rats. There was a strong correlation between IRP and CVP (r = 0.95, p < 0.0001). In the congestion model, more time was required for enhancement of the parenchyma, especially in the medulla compared to control; TTP of the medulla and cortex at 15 mmHg CVP (CVP15) was significantly prolonged compared with controls (medulla, 4351 ± 98 vs. 1415 ± 267 ms, p = 0.003; cortex, 3219 ± 106 vs. 1335 ± 264 ms, p = 0.005). In addition, medullary PI at CVP15 decreased, but not significantly, compared to those of controls and at 10 mmHg CVP (20.1 ± 0.9, 22.8 ± 1.6, 21.6 ± 0.2 dB). In contrast, cortical PIs at CVP15 were significantly lower than that of control (24.6 ± 1.0 vs. 31.4 ± 1.0 dB, p = 0.007). CEUS revealed that impaired renal parenchymal flow in an acute congestion model is accompanied with increased renal interstitial pressure.