Extracardiac Signs of Fluid Overload in the Critically Ill Cardiac Patient: A Focused Evaluation Using Bedside Ultrasound

Prevalence of abnormal common femoral vein pulsatility on Doppler ultrasound in patients undergoing cardiac surgery and its association with adverse events: a prospective cohort study

PURPOSE

Doppler ultrasound assessment of common femoral vein (CFV) flow could represent a simple, fast, and noninvasive technique to identify right ventricular dysfunction and venous congestion in patients undergoing cardiac surgery. Our primary objective was to determine the prevalence of abnormal CFV flow pulsatility before cardiac surgery. Secondary objectives included investigating its association with postoperative outcomes.

METHODS

We conducted a single-centre prospective cohort study and recruited adult patients undergoing cardiac surgery with cardiopulmonary bypass. We performed pulsed-wave Doppler ultrasound assessments of CFV flow at four timepoints: before surgery, after induction of anesthesia, immediately after surgery, and on postoperative day 1. When the Doppler profile showed cardiophasic variations in velocities, abnormal pulsatility was defined as a CFV pulsatility fraction ≥ 100%. Outcomes included postoperative complications, duration of postoperative support, and the cumulative time of persistent organ dysfunction after surgery (TPOD).

RESULTS

Among the 150 patients included, 30 (20%) presented abnormal CFV pulsatility (pulsatility fraction [PF] ≥ 100%) before surgery. Preoperative abnormal CFV pulsatility was associated with a higher proportion of postoperative acute kidney injury (35% vs 16%; P = 0.02), major complications (21% vs 7%; P = 0.02), and a longer duration of TPOD (median [interquartile range]; 24 [9-56] hr vs 5 [3-19] hr; P < 0.001). After adjusting for the European System for Cardiac Operative Risk Evaluation II, the association between PF ≥ 100% before surgery and TPOD remained statistically significant (β = 0.72; 95% confidence interval, 0.21 to 1.23; P = 0.01). An abnormal CFV Doppler was associated with higher right atrial pressure and tricuspid regurgitation.

CONCLUSIONS

Abnormal CFV flow pulsatility occurred in 20% of patients before cardiac surgery and was associated with a higher rate of major postoperative complications, longer durations of postoperative support and care, and a longer cumulative time of persistent organ dysfunction after surgery.

STUDY REGISTRATION

ClinicalTrials.gov ( NCT05038267 ); first submitted 28 August 2021.

Point-of-Care Ultrasonography in the Critical Care Unit: An Update

PURPOSE OF REVIEW

This article outlines updates in point of care ultrasonography.

RECENT FINDINGS

Improving diagnostic accuracy and image quality is continuing to evolve in Point-of-care ultrasonography (POCUS). This include incorporating Artificial Intelligence (AI) and use of other modalities such as Doppler in lung ultrasonography. Transesophageal echocardiography is an emerging option when imaging is difficult to obtain via transthoracic echocardiography. POCUS is becoming instrumental when used during cardiac arrest. Ultrasound (VExUS) Grading System is a promising measurement to assess a patient's volume status. Given the multiple advantages of POCUS usage, competency in POCUS became a requirement of Critical Care fellowship training. POCUS is an important diagnostic modality and guide to medical management. New technological advances such as AI, can serve as a guide to enhance image quality and help accurately obtain quantitative assessments. POCUS has a major role during cardiac arrest and advanced cardiac life support. The clinical utility of POCUS was further substantiated during the COVID-19 pandemic. The Accreditation Council for Graduate Medical Education (ACGME) requires critical care programs to include competency in POCUS as part of their training.

Ultrasonographic Evaluation of Systemic Venous Congestion in Maintenance Hemodialysis Patients during Fluid Removal

INTRODUCTION

Fluid overload is a frequent and serious complication in hemodialysis patients. The combination of multiple point-of-care ultrasound (POCUS) measurements can identify significant venous congestion, but its usefulness to determine ultrafiltration (UF) requirements and dry weight is unknown. Therefore, we evaluated prospectively patients in maintenance hemodialysis to establish the correlations between changes in venous congestion parameters and fluid removal.

METHODS

This was a prospective, single-center, observational study. POCUS venous congestion measurements were performed in 22 patients during 32 online post-dilutional hemodiafiltration sessions, and findings were correlated with UF volume, central venous pressure, and body water composition determined by multifrequency bioelectric impedance analysis (BIA).

RESULTS

The pre-dialysis weight was on average 1.9 kg above the BIA estimated dry weight, the average initial inferior vena cava (IVC) diameter was <2 cm. An initial abnormal hepatic vein (HV) waveform was present in 26% (8) of the measurements. The average UF volume was 2,084 ± 655 mL and correlated with changes in IVC diameter (R = 0.34, 95% CI: [0.18, 0.56], p < 0.05) but not with any other POCUS venous congestion parameters. Normalization of the IVC diameter and HV waveform was observed during the first UF hour in all initially altered measurements. Diameter reduction in the IVC correlated with total body water volume reduction estimated with BIA when measured immediately after fluid removal (R = 0.34, 95% CI: [0.08, 0.56], p < 0.05).

CONCLUSION

Reduction in IVC diameter had a modest but significant correlation with UF volume in our patients on maintenance hemodiafiltration. POCUS may be used to monitor patients during UF.

Exploration of factors affecting hemodynamic stability following pheochromocytoma resection - cohort study

Purpose

Surgery is the only way to cure pheochromocytoma; however, postoperative hemodynamic instability is one of the main causes of serious complications and even death. This study's findings provide some guidance for improved clinical management.

Patients and methods

This study was to investigate the factors leading to postoperative hemodynamic instability in the postoperative pathology indicated pheochromocytoma from May 2016 to May 2022. They were divided into two groups according to whether vasoactive drugs were used for a median number of days or more postoperatively. The factors affecting the postoperative hemodynamics in the perioperative period (preoperative, intraoperative, and postoperative) were then evaluated.

Results

The median number of days requiring vasoactive drug support postoperatively was three in 234 patients, while 118 (50.4%) patients required vasoactive drug support for three days or more postoperatively. The results of the multivariate analysis indicated more preoperative colloid use (odds ratio [OR]=1.834, confidence interval [CI]:1.265-2.659, P=0.001), intraoperative use of vasoactive drug (OR=4.174, CI:1.882-9.258, P<0.001), and more postoperative crystalloid solution input per unit of body weight per day (ml/kg/d) (OR=1.087, CI:1.062-1.112, P<0.001) were risk factors for predicting postoperative hemodynamic instability. The optimal cutoff point of postoperative crystalloid use were 42.37 ml/kg/d.

Conclusion

Hemodynamic instability is a key issue for consideration in the perioperative period of pheochromocytoma. The amount of preoperative colloid use, the need for intraoperative vasoactive drugs, and postoperative crystalloid solution are risk factors for predicting postoperative hemodynamic instability (registration number: ChiCT2300071166).

Transesophageal echocardiographic acquisition of the venous excess ultrasound exam-a case series and technical description

PURPOSE

Obtaining an objective, reproducible, and accurate assessment of volume status is one of the more difficult tasks in the perioperative arena. Since its advent in 2020, the Venous Excess Ultrasound (VExUS) score has gained popularity in the minimally invasive assessment of venous congestion. The VExUS exam has been well described as an additional series of images (hepatic vein, portal vein, and intrarenal vein) obtained with a phased-array probe during a transthoracic echocardiogram. Nevertheless, there are no descriptions of comprehensive VExUS exams performed using transesophageal echocardiography (TEE)-a modality that is routinely employed in patients undergoing cardiac surgery.

CLINICAL FEATURES

We describe techniques to acquire and interpret a comprehensive TEE-supported VexUS exam, which may be used to optimize the perioperative care of cardiac surgical patients.

CONCLUSION

Given the risks of fluid overload in critically ill cardiac surgery patients, TEE-supported VExUS examination may be a way to reduce morbidity in this population.

Prospective Study of Ultrasound Markers of Organ Congestion in Critically Ill Patients With Acute Kidney Injury

INTRODUCTION

Organ congestion may be a mediator of adverse outcomes in critically ill patients with severe acute kidney injury (AKI). The presence of abnormal venous Doppler waveforms could identify patients with clinically significant organ congestion who may benefit from a decongestive strategy.

METHODS

This prospective multicenter cohort study enrolled patients with severe AKI defined as Kidney Disease: Improving Global Outcomes stage 2 or higher. Patients were not eligible if they received renal replacement therapy (RRT) for more than 72 hours at the time of screening. Participants underwent serial Doppler ultrasound examinations of the portal, hepatic and intrarenal veins during the week following enrolment. We calculated the venous excess ultrasound (VExUS) score based on these data. The primary outcome studied was major adverse kidney events at 30 days (MAKE30) defined as death, RRT dependence, or a persistent decrease in kidney function.

RESULTS

A total of 125 patients were included for whom 291 ultrasound assessments were performed. Severely abnormal venous waveforms were documented in 14.4% of portal vein assessments, 6.5% of intrarenal venous assessments, and 14.4% of hepatic vein assessments. The individual ultrasound markers were not associated with MAKE30. The VExUS score (grade 0-1: reference; grade 2: adjusted hazard ratio [aHR]: 4.03, confidence interval [CI]: 1.81-8.99; grade 3: aHR: 2.70, CI: 1.10-6.65; P = 0.03), as well as severely abnormal portal, hepatic and intrarenal vein Doppler were each independently associated with mortality.

CONCLUSION

Although not significantly associated with MAKE30, venous Doppler abnormalities suggestive of venous congestion were associated with higher mortality in critically ill patients with severe AKI.

On Whether Ca-125 Is the Answer for Diagnosing Overhydration, Particularly in End-Stage Kidney Disease Patients-A Systematic Review

Overhydration (OH) is a prevalent medical problem that occurs in patients with kidney failure, but a specific marker has still not been found. Patients requiring kidney replacement therapy suffer from a water imbalance, which is correlated with mortality rates in this population. Currently, clinicians employ techniques such as bioimpedance spectroscopy (BIS) and ultrasound (USG) markers of overhydration or markers of heart and kidney function, namely NT-pro-BNP, GFR, or creatinine levels. New serum markers, including but not limited to Ca-125, galectin-3 (Gal-3), adrenomedullin (AMD), and urocortin-2 (UCN-2), are presently under research and have displayed promising results. Ca-125, which is a protein mainly used in ovarian cancer diagnoses, holds great potential to become an OH marker. It is currently being investigated by cardiologists as it corresponds to the volume status in heart failure (HF) and ventricular hypertrophy, which are also associated with OH. The need to ascertain a more precise marker of overhydration is urgent mainly because physical examinations are exceptionally inaccurate. The signs and symptoms of overhydration, such as edema or a gradual increase in body mass, are not always present, notably in patients with chronic kidney disease. Metabolic disruptions and cachexia can give a false picture of the hydration status. This review paper summarizes the existing knowledge on the assessment of a patient's hydration status, focusing specifically on kidney diseases and the role of Ca-125.

Comparison of various surrogate markers for venous congestion in predicting acute kidney injury following cardiac surgery: A cohort study

BACKGROUND

Venous congestion has been demonstrated to increase the risk of acute kidney injury (AKI) after cardiac surgery. Although many surrogate markers for venous congestion are currently used in clinical settings, there is no consensus on which marker is most effective in predicting AKI.

METHODS

We evaluated various markers of venous congestion, including central venous pressure (CVP), inferior vena cava (IVC) diameter, portal pulsatility fraction (PPF), hepatic vein flow pattern (HVF), intra-renal venous flow pattern (IRVF), and venous excess ultrasound grading score (VExUS) in adult patients undergoing cardiac surgery to compare their ability in predicting AKI.

RESULTS

Among the 230 patients enrolled in our study, 53 (23.0%) developed AKI, and 11 (4.8%) required continuous renal replacement therapy (CRRT). Our multivariate logistic analysis revealed that IRVF, PPF, HVF, and CVP were significantly associated with AKI, with IRVF being the strongest predictor (odds ratio [OR] 2.27; 95% confidence interval [CI], 1.38-3.73). However, we did not observe any association between these markers and CRRT.

CONCLUSION

Venous congestion is associated with AKI after cardiac surgery, but not necessarily with CRRT. Among the markers tested, IRVF exhibits the strongest correlation with AKI.

Extracorporeal veno-venous ultrafiltration in congestive heart failure: What's the state of the art? A mini-review

Hospitalizations for heart failure exceed 1 million per year in both the United States and Europe and more than 90% are due to symptoms and signs of fluid overload. Rates of rehospitalizations or emergency department visit at 60 days are remarkable regardless of whether loop diuretics were administered at low vs high doses or by bolus injection vs continuous infusion. Ultrafiltration (UF) has been considered a promising alternative to stepped diuretic therapy and it consists in the mechanical, adjustable removal of iso-tonic plasma water across a semipermeable membrane with the application of hydrostatic pressure gradient generated by a pump. Fluid removal with ultrafiltration presents several advantages such as elimination of higher amount of sodium with less neurohormonal activation. However, the conflicting results from UF studies highlight that patient selection and fluid removal targets are not completely understood. The best way to assess fluid status and therefore establish the fluid removal target is also still a matter of debate. Herein, we provide an up-to-date systematic review about the role of ultrafiltration among patients with fluid overload and its gaps in daily practice.

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.

Prolonged cardiovascular pharmacological support and fluid management after cardiac surgery

OBJECTIVE

To identify potentially modifiable risk factors related to prolonged cardiovascular pharmacological support after weaning from cardiopulmonary bypass (CPB).

METHODS

This is a secondary analysis of two prospective cohort study in a specialized cardiac surgery institution in adult patients undergoing cardiac surgery with the use of CPB between August 2016 and July 2017. Prolonged cardiovascular pharmacological support was defined by the need for at least one vasopressor or one inotropic agent 24 hours after separation from CPB. Risk factors were identified among baseline characteristics and peri-operative events through multivariable logistic regression.

RESULTS

A total of 247 patients were included and 98 (39.7%) developed prolonged pharmacological support. In multivariable analysis, left ventricular ejection fraction ≤ 30% (OR 9.52, 95% confidence interval (CI) 1.14; 79.25), elevated systolic pulmonary artery pressure (sPAP) > 30 and ≤ 55 mmHg (moderate) (OR 2.52, CI 1.15; 5.52) and sPAP > 55 mmHg (severe) (OR 8.12, CI 2.54; 26.03), as well as cumulative fluid balance in the first 24 hours after surgery (OR 1.76, CI 1.32; 2.33) were independently associated with the development of prolonged pharmacological support.

CONCLUSIONS

Prolonged cardiovascular pharmacological support is frequent after cardiac surgery on CPB. Severe LV systolic dysfunction, preoperative pulmonary hypertension and postoperative fluid overload are risk factors. Further studies are required to explore if those risk factors could be modified or not.

Pulsatile Femoral Vein Doppler and Congestive Delirium, What Is the Relationship?: A Case Report

Delirium is common in patients undergoing cardiac surgery, and venous congestion has been reported as an important risk factor. We report a 69-year-old patient who developed postoperative delirium in the intensive care unit following aortic valve replacement surgery. The postoperative course was complicated by delirium for which echographic signs of venous congestion on the portal and the renal but also the femoral veins and their resolution correlated with the course of delirium. The use of common femoral vein Doppler as a simple bedside technique to predict and identify congestive delirium has not been reported before.

Point-of-Care Ultrasound in the Intensive Care Unit: Applications, Limitations, and the Evolution of Clinical Practice

The use of point-of-care ultrasonography in the intensive care unit has been rapidly advancing over the past 20 years. This review will provide a broad overview of the discipline spanning lung ultrasonography to advanced critical care echocardiography. It will highlight new research that questions the utility of the inferior vena cava for determining volume responsiveness and will introduce the reader to cutting-edge technology including artificial intelligence, which is likely to revolutionize ultrasound teaching and image interpretation, increasing the reach of this modality for the frontline clinician.

Diagnostic Utility of Point-of-Care Ultrasound in the Pediatric Cardiac Intensive Care Unit

Purpose of Review

Recent Findings

Summary

Supplementary Information

BESTFIT-T3: A Tiered Monitoring Approach to Persistent/Recurrent Paediatric Septic Shock - A Pilot Conceptual Report

Objective

Persistent shock (PS) or recurrent shock (RS) after initial fluids and vasoactives can be secondary to myriad complex mechanisms, and these patients can have a high mortality. We developed a noninvasive tiered hemodynamic monitoring approach which included, in addition to basic echocardiography, cardiac output monitoring and advanced Doppler studies to determine the etiology and provide targeted therapy of PS/RS.

Design

Prospective observational study.

Setting

Tertiary Care Pediatric Intensive Care Unit, India.

Methods

A pilot conceptual report describing the clinical presentation of 10 children with PS/RS using advanced ultrasound and noninvasive cardiac output monitoring. Children with PS/RS after initial fluids and vasoactive agents despite basic echocardiography underwent BESTFIT + T3 (Basic Echocardiography in Shock Therapy for Fluid and Inotrope Titration) with lung ultrasound and advanced 3-tiered monitoring (T1-3).

Results

Among 10/53 children with septic shock and PS/RS over a 24-month study period, BESTFIT + T3 revealed combinations of right ventricular dysfunction, diastolic dysfunction (DD), altered vascular tone, and venous congestion (VC). By integrating information obtained by BESTFIT + T1-3 and the clinical context, we were able to modify the therapeutic regimen and successfully reverse shock in 8/10 patients.

Conclusion

We present our pilot results with BESTFIT + T3, a novel approach that can noninvasively interrogate major cardiac, arterial, and venous systems that may be particularly useful in regions where expensive rescue therapies are out of reach. We suggest that, with practice, intensivists already experienced in bedside POCUS can use the information obtained by BESTFIT + T3 to direct time-sensitive precision cardiovascular therapy in persistent/recurrent pediatric septic shock.

How to cite this article

Natraj R, Ranjit S. BESTFIT-T3: A Tiered Monitoring Approach to Persistent/Recurrent Paediatric Septic Shock - A Pilot Conceptual Report. Indian J Crit Care Med 2022;26(7):863-870.

New developments in the understanding of right ventricular function in acute care

PURPOSE OF REVIEW

Right ventricular dysfunction has an important impact on the perioperative course of cardiac surgery patients. Recent advances in the detection and monitoring of perioperative right ventricular dysfunction will be reviewed here.

RECENT FINDINGS

The incidence of right ventricular dysfunction in cardiac surgery has been associated with unfavorable outcomes. New evidence supports the use of a pulmonary artery catheter in cardiogenic shock. The possibility to directly measure right ventricular pressure by transducing the pacing port has expanded its use to track changes in right ventricular function and to detect right ventricular outflow tract obstruction. The potential role of myocardial deformation imaging has been raised to detect patients at risk of postoperative complications.

SUMMARY

Perioperative right ventricular function monitoring is based on echocardiographic and extra-cardiac flow evaluation. In addition to imaging modalities, hemodynamic evaluation using various types of pulmonary artery catheters can be achieved to track changes rapidly and quantitatively in right ventricular function perioperatively. These monitoring techniques can be applied during and after surgery to increase the detection rate of right ventricular dysfunction. All this to improve the treatment of patients presenting early signs of right ventricular dysfunction before systemic organ dysfunction ensue.

The Intensivist's Perspective of Shock, Volume Management, and Hemodynamic Monitoring

One of the primary reasons for intensive care admission is shock. Identifying the underlying cause of shock (hypovolemic, distributive, cardiogenic, and obstructive) may lead to entirely different clinical pathways for management. Among patients with hypovolemic and distributive shock, fluid therapy is one of the leading management strategies. Although an appropriate amount of fluid administration might save a patient's life, inadequate (or excessive) fluid use could lead to more complications, including organ failure and mortality due to either hypovolemia or volume overload. Currently, intensivists have access to a wide variety of information sources and tools to monitor the underlying hemodynamic status, including medical history, physical examination, and specific hemodynamic monitoring devices. Although appropriate and timely assessment and interpretation of this information can promote adequate fluid resuscitation, misinterpretation of these data can also lead to additional mortality and morbidity. This article provides a narrative review of the most commonly used hemodynamic monitoring approaches to assessing fluid responsiveness and fluid tolerance. In addition, we describe the benefits and disadvantages of these tools.

Use of Venous Excess UltraSound (VExUS) score in hyponatraemia management in critically ill patient

Hyponatraemia is the most prevalent electrolyte disorder in the neurocritical care setting and is associated with a significant morbimortality. Cerebral salt wasting and inappropriate antidiuretic hormone secretion syndrome have been classically described as the two most frequent entities responsible for hyponatraemia in neurocritical care patients. An accurate aetiological diagnosis of hypotonic hyponatraemia requires a proper volume status assessment. Nevertheless, determination of volume status based on physical examination, laboratory findings and imaging modalities have several limitations and can lead to improperly diagnosis and hyponatraemia mismanagement. Point-of-care ultrasound (POCUS), specifically Venous Excess UltraSound (VExUS) score, is a fast and valuable tool to evaluate venous congestion at the bedside and identify hypervolaemia, helping the physicians in therapeutic decision making in a patient with hyponatraemia. We report a case where the use of POCUS, and more specifically VExUS, can be helpful in volume status assessment, complementing the complex management of multifactorial hyponatraemia in a neurocritical patient.

Ultrasound Hepatic Vein Ratios Are Associated With the Development of Acute Kidney Injury After Cardiac Surgery

OBJECTIVE

The authors investigated the use of hepatic venous and right-heart ultrasound parameters in predicting cardiac surgery-associated acute kidney injury (AKI).

DESIGN

This was a prospective, contextual, descriptive two-center study. Blood tests,clinical and ultrasound data were obtained preoperatively, and postoperative day one, and day four. The hepatic vein, inferior vena cava, and right-heart Doppler ultrasound parameters were obtained and analyzed.

SETTING

The sites of the study were Johannesburg, South Africa, and Aarhus, Denmark.

PARTICIPANTS

Adult patients who satisfied inclusion criteria, between August 2019 and January 2020, were included, with a total of 152 participants.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The median (interquartile range) age of patients was 68 (55-73) years, predominantly male, and the majority were hypertensive. Of 152 patients analyzed, 54 (35%) patients developed AKI. Among these, 37 (69%) were classified as Kidney Disease: Improving Global Outcomes (KDIGO) stage I, 11 (20%) as stage II, while six (11%) were stage III. Age (adjusted odds ratio [AOR] 1.05, 95% confidence interval [CI] 1.00-1.10 p = 0.031), The European System for Cardiac Operative Risk Evaluation (EuroSCORE) II (AOR 1.43, 95% CI 1.14-1.80, p = 0.005], and preoperative serum creatinine (AOR 1.04, 95% CI 1.01-1.08, p = 0.013) were predictive of AKI. Those who developed AKI had experienced longer cardiopulmonary bypass (CPB) times (p < 0.001). Preoperatively, hepatic vein S-wave measurements were significantly higher in patients with AKI (p < 0.05). On postoperative day one (D1), the hepatic vein flow ratios of patients with AKI were significantly decreased, driven by low S waves and high D waves, and accompanied by significantly elevated central venous pressure (CVP) levels. CVP levels on D1 postoperatively were predictive of AKI (AOR 1.31, 95% CI 1.11-1.55, p = 0.001). Measurements of right ventricular (RV) base, tricuspid annular plane excursion (TAPSE), and inferior vena cava were not associated with the development of AKI (p > 0.05).

CONCLUSION

There was an association between the development of AKI and a decrease in hepatic flow ratios on D1, driven by low S-wave and high D-wave velocities. The presence of venous congestion was reflected by significantly elevated CVP values, which were independently associated with AKI on D1. RV base and TAPSE measurements were, however, not associated with AKI. These parameters may reflect perioperative circumstances, including prolonged CPB times and potential fluid management, which can be modified in this period.

Fluid Overload

Fluid overload (FO) is characterized by hypervolemia, edema, or both. In clinical practice it is usually suspected when a patient shows evidence of pulmonary edema, peripheral edema, or body cavity effusion. FO may be a consequence of spontaneous disease, or may be a complication of intravenous fluid therapy. Most clinical studies of the association of FO with fluid therapy and risk of harm define it in terms of an increase in body weight of at least 5–10%, or a positive fluid balance of the same magnitude when fluid intake and urine output are measured. Numerous observational clinical studies in humans have demonstrated an association between FO, adverse events, and mortality, as have two retrospective observational studies in dogs and cats. The risk of FO may be minimized by limiting resuscitation fluid to the smallest amount needed to optimize cardiac output and then limiting maintenance fluid to the amount needed to replace ongoing normal and pathological losses of water and sodium.

Future developments in the imaging of the gastrointestinal tract: the role of ultrasound

PURPOSE OF REVIEW

The purpose of this review is to summarize the utilization and most recent developments with regard to the use of ultrasound when imaging the abdomen and gastrointestinal tract.

RECENT FINDINGS

Although the use of ultrasound to assess the anatomy of the various abdominal organs is well established within radiology and critical care, its use as part of functional and physiological assessment is still evolving. Recent developments have extended the use of ultrasound beyond standard B-mode/2D imaging techniques to incorporate more functional and haemodynamic assessment. These include the use of contrast-enhanced ultrasound (CEUS), elastography, and colour Doppler techniques.

SUMMARY

Whilst Doppler techniques are reasonably well established within critical care ultrasound (CCUS), especially in echocardiography, CEUS and elastography are less well known. CEUS utilizes a purely intravascular contrast agent whilst elastography measures the degree of deformation or stiffness in various organs. Whilst their use individually may be limited; they may play a role in a multiparametric assessment. Mirroring the overall trends in critical care ultrasound development, abdominal ultrasound assessment is best integrated in a holistic approach and adapted to the individual patient.

Validation of Point-of-Care Ultrasound to Measure Perioperative Edema in Infants With Congenital Heart Disease

Purpose: Fluid overload is a common post-operative issue in children following cardiac surgery and is associated with increased morbidity and mortality. There is currently no gold standard for evaluating fluid status. We sought to validate the use of point-of-care ultrasound to measure skin edema in infants and assess the intra- and inter-user variability. Methods: Prospective cohort study of neonates (≤30 d/o) and infants (31 d/o to 12 m/o) undergoing cardiac surgery and neonatal controls. Skin ultrasound was performed on four body sites at baseline and daily post-operatively through post-operative day (POD) 3. Subcutaneous tissue depth was manually measured. Intra- and inter-user variability was assessed using intraclass correlation coefficient (ICC). Results: Fifty control and 22 surgical subjects underwent skin ultrasound. There was no difference between baseline surgical and control neonates. Subcutaneous tissue increased in neonates starting POD 1 with minimal improvement by POD 3. In infants, this pattern was less pronounced with near resolution by POD 3. Intra-user variability was excellent (ICC 0.95). Inter-user variability was very good (ICC 0.82). Conclusion: Point-of-care skin ultrasound is a reproducible and reliable method to measure subcutaneous tissue in infants with and without congenital heart disease. Acute increases in subcutaneous tissue suggests development of skin edema, consistent with extravascular fluid overload. There is evidence of skin edema starting POD 1 in all subjects with no substantial improvement by POD 3 in neonates. Point-of-care ultrasound could be an objective way to measure extravascular fluid overload in infants. Further research is needed to determine how extravascular fluid overload correlates to clinical outcomes.

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.

Fluid Removal With Ultrasound Guided Protocol Improves the Efficacy and Safety of Dehydration in Post-Resuscitated Critically Ill Patients: A Quasi-Experimental, Before and After Study

Fluid overload is associated with increased morbidity and mortality in critically ill patients. However, researches rarely study the precise start or end point of fluid removal and no protocol was developed to control the fluid removal process. We hypothesized that individualized fluid removal with ultrasound-guided protocol could improve the efficacy and safety of fluid removal in post-resuscitated critically ill patients. A quasi-experimental, before and after trial was conducted to identify the benefits of ultrasound-guided fluid removal. Fluid removal was performed either following the doctor's experience in Control group, or abiding the ultrasound guided protocol in Ultrasound group. The study end points were the start time, end time, length of fluid removal, and the complications related to fluid removal. A total of 85 subjects were finally analyzed in this study. The fluid removal was started earlier, completed quicker and ended earlier (21.0 ± 14.6 h vs. 35.1 ± 26.5 h, 49.8 ± 32.6 vs. 93.0 ± 42.8 h, 69.0 ± 32.2 h vs. 126.4 ± 52.5 h, P < 0.05) in Ultrasound group than in Control. The subjects had more daily negative fluid balance and urine output (-990.4 ± 636.1 mL vs. -723.6 ± 549.5 mL, 2425.8 ± 886.7 mL vs. 1560.7 ± 1125.3 mL, P < 0.05) in Ultrasound group. The time of lung B-lines to reduce to zero was shorter and B-line at the end point was less (49.5 ± 36.6 h vs. 75.6 ± 58.8 h, 0[1] vs. 0[0], P < 0.05) in Ultrasound group. The length of intensive care unit stay in shock subgroup had a tendency to shorten (96.1 ± 61.5 h vs. 174.6 ± 132.0 h, P > 0.05) in Ultrasound group. We concluded that fluid removal with individualized ultrasound-guided protocol improves the efficacy and safety of dehydration in critically ill patients.

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.

Whole body ultrasound in the operating room and intensive care unit

Whole body ultrasound can be used to improve the speed and accuracy of evaluation of an increasing number of organ systems in the critically ill. Cardiac and abdominal ultrasound can be used to identify the mechanisms and etiology of hemodynamic instability. In hypoxemia or hypercarbia, lung ultrasound can rapidly identify the etiology of the condition with an accuracy that is equivalent to that of computed tomography. For encephalopathy, ocular ultrasound and transcranial Doppler can identify elevated intracranial pressure and midline shift. Renal and bladder ultrasound can identify the mechanisms and etiology of renal failure. Ultrasound can also improve the accuracy and safety of percutaneous procedures and should be currently used routinely for central vein catheterization and percutaneous tracheostomy.

Can regional cerebral oxygen saturation guide red blood cell transfusion in high risk cardiac surgery?

INTRODUCTION

Cardiac surgery (CS) is associated with a significant use of blood products. The aim of this study was to evaluate the effect of red blood cells concentrates (RBC) transfusion on regional cerebral oxygen saturation (SrO₂) in patients undergoing CS with additive EuroSCORE I > 6.

MATERIAL AND METHODS

This is a prospective descriptive study. Patients with additive EuroSCORE I > 6 undergoing CS with extracorporeal circulation were included in the study. The demographic values, perioperative complications, hospital/ICU length of stay (LOS), as well as the preinduction baseline SrO₂values, the lowest SrO₂ value during surgery, number of blood products transfused, hemoglobine (HB) and pre and postransfusional SrO2 values were recorded, and events of significant decrease in SrO₂ below 20% of basal value or decrease below 50%. We considered responders those who had an increase post-transfusion SrO₂ at least 20% of pre-transfusion value, an increase of standar deviation (7.9) or an increase up to basal SrO₂.

RESULTS

Data from 57 patients were collected. The average additive EuroSCORE I was 7.4 (SD 2.6) and the EuroSCORE II was 6.1 (SD 7.4). 52% were male. 35.1% of patients received intraoperative transfusion of at least one unit of RBC. The overall mortality was 8.7% (N = 5). During surgery 29.8% of the overall sample presented a decrease of more than 20% of baseline SrO2 or a value lower than 50%. Patients with a significant decrease in SrO2 presented a higher rate of perioperative complications (P=0.04) and longer ICU-LOS 4.3 (SD 3.6) vs. 6.8 (SD 8.2) days (P=0.01) and hospital LOS 10.1 (SD 3.1) vs. 14.2 (SD 9.4) days (P=0.01). Pretransfusional HB was 7.4 (SD 0.8) mg/dl and postransfusional value was 8.4 (SD 0.8) (P =0.00). Pretransfusional SrO2 was 59 (SD 8.6) and increased non- significantly after RBC transfusion to 61.1 (SD 7.9) (P=0.1). Only 6 patients out of 21 could be considered responders. There were no significant differences in morbidity, mortality or LOS between responders and non-responders.

DISCUSSION

In our population a non statistically significant increase in SrO2 was observed after RBC transfusion. When considering responders few patients were identified by SrO₂. In conclusion SrO₂ might not be reliable triger to decide transfusion.

The Role of Point-of-Care Ultrasound Monitoring in Cardiac Surgical Patients With Acute Kidney Injury

The approach to the patient with acute kidney injury (AKI) after cardiac surgery involves multiple aspects. These include the rapid recognition of reversible causes, the accurate identification of patients who will progress to severe stages of AKI, and the subsequent management of complications resulting from severe renal dysfunction. Unfortunately, the inherent limitations of physical examination and laboratory parameter results are often responsible for suboptimal clinical management. In this review article, the authors explore how point-of-care ultrasound, including renal and extrarenal ultrasound, can be used to complement all aspects of the care of cardiac surgery patients with AKI, from the initial approach of early AKI to fluid balance management during renal replacement therapy. The current evidence is reviewed, including knowledge gaps and future areas of research.

Delirium After Cardiac Surgery and Cumulative Fluid Balance: A Case-Control Cohort Study

OBJECTIVE

To assess a novel hypothesis to explain delirium after cardiac surgery through the relationship between cumulative fluid balance and delirium. This hypothesis involved an inflammatory process combined with a hypervolemic state, which could lead to venous congestion reaching the brain.

DESIGN

Retrospective case-control (1:1) cohort study.

SETTING

University-affiliated tertiary cardiology center.

PARTICIPANTS

Cardiac surgery intensive care unit (ICU) patients.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Cumulative fluid balance was evaluated at 3 times: (1) upon arrival at the ICU after surgery, (2) 24 hours post-ICU arrival, and (3) 48 hours post-ICU arrival. A generalized estimated equation was used to model the association between cumulative fluid balance and delirium occurrence 24 hours later. Covariates were selected based on the statistical differences between cases and controls on delirium risk factors and clinical characteristics. The cohort included 346 patients, of which 39 (11%), 104 (30%), and 142 patients (41%) presented delirium at 24, 48, and 72 hours post-ICU arrival, respectively. The effect of time had an odds ratio (OR) of 2.14, 95% confidence interval (CI) 1.603 to 2.851, and a p value < 0.001. The cumulative fluid balance was associated with delirium occurrence (OR 1.20, 95% CI: 1.066-1.355, p = .003). History of neurological disorder, having both hearing and visual impairment, type of procedure, perioperative cerebral oximetry, mean pulmonary artery pressure pre-cardiopulmonary bypass (CPB), and mean arterial pressure post-CPB also contributed to delirium in the model.

CONCLUSION

Delirium is associated with a cumulative fluid balance, but the extent through which this plays an etiologic role remains to be determined.

Aerosolized Vasodilators for the Treatment of Pulmonary Hypertension in Cardiac Surgical Patients: A Systematic Review and Meta-analysis

BACKGROUND

In cardiac surgery, pulmonary hypertension is an important prognostic factor for which several treatments have been suggested over time. In this systematic review and meta-analysis, we compared the efficacy of inhaled aerosolized vasodilators to intravenously administered agents and to placebo in the treatment of pulmonary hypertension during cardiac surgery. We searched MEDLINE, CENTRAL, EMBASE, Web of Science, and clinicaltrials.gov databases from inception to October 2015. The incidence of mortality was assessed as the primary outcome. Secondary outcomes included length of stay in hospital and in the intensive care unit, and evaluation of the hemodynamic profile.

METHODS

Of the 2897 citations identified, 10 studies were included comprising a total of 434 patients.

RESULTS

Inhaled aerosolized agents were associated with a significant decrease in pulmonary vascular resistance (-41.36 dyne·s/cm, P= .03) and a significant increase in mean arterial pressure (8.24 mm Hg, P= .02) and right ventricular ejection fraction (7.29%, P< .0001) when compared to intravenously administered agents. No significant hemodynamically meaningful differences were observed between inhaled agents and placebo; however, an increase in length of stay in the intensive care unit was shown with the use of inhaled aerosolized agents (0.66 days, P= .01). No other differences were observed for either comparison.

CONCLUSIONS

The administration of inhaled aerosolized vasodilators for the treatment of pulmonary hypertension during cardiac surgery is associated with improved right ventricular performance when compared to intravenously administered agents. This review does not support any benefit compared to placebo on major outcomes. Further investigation is warranted in this area of research and should focus on clinically significant outcomes.