Renal Resistive Index Measurement by Transesophageal Echocardiography: Comparison With Translumbar Ultrasonography and Relation to Acute Kidney Injury

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.

Association of Preoperative Renal-Resistive Index With Long-term Renal and Cardiovascular Outcomes After Cardiac Surgery

OBJECTIVE

To investigate the association of elevated preoperative renal-resistive index (RRI) with persistent renal dysfunction, major adverse kidney events (MAKE), and major adverse cardiovascular events (MACE) after cardiac surgery.

DESIGN

Observational cohort study.

SETTING

University hospital.

PARTICIPANTS

Ninety-six adult patients undergoing cardiac surgery.

INTERVENTIONS

RRI measurement the day before surgery.

MEASUREMENTS AND MAIN RESULTS

Fifty-eight patients (60%) had elevated RRI ≥0.70. Five years after surgery, persistent renal dysfunction (sustained decline in estimated glomerular filtration rate ≥25%) had occurred in 25 patients (26%), MAKE (persistent renal dysfunction, renal replacement therapy, or death) in 34 (35%), and MACE (myocardial infarction, unstable angina, decompensated heart failure, stroke, or cardiovascular death) in 28 (29%). RRI was higher in patients who developed persistent renal dysfunction (median, 0.78 [IQR, 0.74-0.82] v 0.70 [0.66-0.77], p = 0.001), MAKE (0.77 [0.72-0.81] v 0.68 [0.65-0.76], p = 0.002), and MACE (0.77 [0.72-0.81] v 0.70 [0.66-0.77], p = 0.006). Patients with elevated RRI had a significantly higher cumulative incidence of all long-term outcomes. After adjustment for baseline renal function and heart failure, elevated RRI was associated with persistent renal dysfunction (hazard ratio [HR], 5.82 [95% CI, 1.71-19.9]), MAKE (HR, 4.21 [1.59-11.1]), and MACE (HR, 2.81 [1.03-7.65]).

CONCLUSIONS

Elevated preoperative RRI is associated with persistent renal dysfunction, MAKE, and MACE after cardiac surgery. Preoperative RRI may be used for long-term risk assessment in patients undergoing cardiac surgery.

Clinical and experimental approaches for imaging of acute kidney injury

Complex molecular cell dynamics in acute kidney injury and its heterogeneous etiologies in patient populations in clinical settings have revealed the potential advantages and disadvantages of emerging novel damage biomarkers. Imaging techniques have been developed over the past decade to further our understanding about diseased organs, including the kidneys. Understanding the compositional, structural, and functional changes in damaged kidneys via several imaging modalities would enable a more comprehensive analysis of acute kidney injury, including its risks, diagnosis, and prognosis. This review summarizes recent imaging studies for acute kidney injury and discusses their potential utility in clinical settings.

Transgastric Abdominal Ultrasonography in Anesthesia and Critical Care: Review and Proposed Approach

The use of transesophageal echocardiography (TEE) in the operating room and intensive care unit can provide invaluable information on cardiac as well as abdominal organ structures and function. This approach may be particularly useful when the transabdominal ultrasound examination is not possible during intraoperative procedures or for anatomical reasons. This review explores the role of transgastric abdominal ultrasonography (TGAUS) in perioperative medicine. We describe several reported applications using 10 views that can be used in the diagnosis of relevant abdominal conditions associated with organ dysfunction and hemodynamic instability in the operating room and the intensive care unit.

The predictive value of the intraoperative Renal Pulsatility Index for acute kidney injury in patients undergoing cardiac surgery

BACKGROUND

The incidence of cardiac surgery-associated acute kidney injury (CSA-AKI) is very high. The Renal Resistive Index (RRI) is measured by transesophageal echocardiography (TEE) and can be used to predict the occurrence of CSA-AKI, but few studies have examined the Renal Pulsatility Index (RPI). The objective of this study was to explore the predictive value of intraoperative RPI for CSA-AKI.

METHODS

This study was a prospective observational study. Seventy-eight patients meeting the inclusion criteria were enrolled. The RPI was measured by TEE after the induction of general anesthesia (T1) and immediately after the surgery (T2). Serum creatinine (Scr) was measured one day before and seven days after the surgery. The diagnosis of AKI was based on the KDIGO diagnostic criteria. Multivariate logistic regression analysis was used to analyze the risk factors for postoperative AKI and to draw the receiver operating characteristic curve (ROC) and analyze its diagnostic value for AKI.

RESULTS

The incidence of postoperative AKI was 29.5%. The RPI at T2 was higher in the AKI group than in the non-AKI group (2.05±0.69 versus 1.49±0.48, P<0.001). The results of multivariate analysis showed that the RPI at T2 was an independent risk factor for the occurrence of AKI (OR=4.683, 95% CI: 1.592-13.772; P=0.006). The area under the curve (AUC) of the RPI was 0.733 (95% CI: 0.621-0.827) with a cut-off value of 1.86 (sensitivity 60.87%, specificity 85.45% and Youden Index 0.46).

CONCLUSIONS

An RPI at T2>1.86 is correlated with a higher incidence of postoperative AKI. Treatment guided and personalized on the base of this parameter should be investigated by further dedicated studies.

Intraoperative renal resistive index threshold as an acute kidney injury biomarker

STUDY OBJECTIVE

The lag in creatinine-mediated diagnosis of cardiac surgery-associated acute kidney injury (AKI) may be impeding the development of renoprotection therapies. Postoperative renal resistive index (RRI) measured by transabdominal Doppler ultrasound is a promising early AKI biomarker. RRI measured intraoperatively by transesophageal echocardiography (TEE) is available even earlier but is less evaluated. Therefore, we conducted an assessment of intraoperative RRI as an AKI biomarker using previously reported post-renal insult thresholds.

DESIGN

Retrospective convenience sample.

SETTING

Intraoperative.

PATIENTS

180 adult cardiac surgical patients between July 2013 and July 2014.

INTERVENTION

None.

MEASUREMENTS

Pre- and post-cardiopulmonary bypass (CPB) RRI thresholds, measured using intraoperative TEE, exceeding 0.74 or 0.79 were used to evaluate for an association with KDIGO AKI risk using the Chi-square test. Other consensus AKI criteria (AKIN, RIFLE) were similarly evaluated. Additional t-test analyses examined the relationship of pre- and pre-to-post (delta) CPB RRI with AKI.

MAIN RESULTS

Post-CPB RRI for 99 patients included 36 and 23 with values exceeding 0.74 and 0.79, respectively. Analyses confirmed associations of both RRI thresholds with all consensus AKI definitions (0.74; KDIGO: p = 0.05, AKIN: p = 0.03, RIFLE: p = 0.03, 0.79; KDIGO: p = 0.002, AKIN: p = 0.001, RIFLE: p = 0.004). In contrast, pre-CPB and pre-to post-CPB RRI were not associated with AKI.

CONCLUSIONS

RRI obtained intraoperatively in cardiac surgery patients, assessed using previously reported thresholds, is highly associated with AKI and warrants further evaluation as a promising "earliest" AKI biomarker. These significant findings suggest that RRI assessment should be included in the standard intraoperative TEE exam.

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.

Combination of the fetal urinary metabolome and peptidome for the prediction of postnatal renal outcome in fetuses with PUV

Most of biomarker panels, extracted from single omics traits, still need improvement since they display a gray zone where prediction is uncertain. Here we verified whether a combination of omics traits, fetal urinary metabolites and peptides analyzed in the same sample, improved prediction of postnatal renal function in fetuses with posterior urethral valves (PUV) compared to individual omics traits. Using CE-MS, we explored the urinary metabolome of 13 PUV fetuses with end stage renal disease (ESRD) and 12 PUV fetuses without postnatal ESRD at 2 years postnatally. This allowed the selection of 24 differentially abundant metabolite features which were modelled into predictive classifiers, alone or in combination with 12 peptides previously identified as predictive of ESRD. Validation in 35 new fetuses showed that the combination of peptides and metabolites significantly outperformed the 24 metabolite features with increased AUC (0.987 vs 0.905), net reclassification improvement (36%) and better sensitivity accuracy (86% vs 60%). In addition, the two trait combination tended to improve, but without reaching statistical significance, the already high performances of the 12 peptide biomarkers (AUC 0.967, accuracy 80%). In conclusion, this study demonstrates the potential of cumulating different omics traits in biomarker research where single omics traits fall short.

SIGNIFICANCE

Although increasingly proposed in disease-diagnosis and -prognosis because of their improved efficacy over single markers, panels of body fluid biomarkers based on single omics analysis still fail to display perfect accuracy, probably due to biological variability. Here, we hypothesized that combination of different omics traits allowed to better capture this biological variability. As proof of concept, we studied the added value of fetal urine metabolites and peptides using CE-MS, starting from the same urine sample, to predict postnatal renal outcome in fetuses with posterior urethral valves. We observed that the prognostic power of combined metabolite and peptide markers was clearly higher than that of metabolites alone and slightly, but non-significantly, improved compared to the peptides alone. To our knowledge, this report is the first to demonstrate that combining multiomics traits extracted from (fetal) urine samples displays clear promise for kidney disease stratification.

Perioperative Acute Kidney Injury: Risk Factors and Predictive Strategies

Acute kidney injury (AKI) is a common complication in surgical patients and is associated with increases in mortality, an increased risk for chronic kidney disease and hemodialysis after discharge, and increased cost. Better understanding of the risk factors that contribute to perioperative AKI has led to improved AKI prediction and will eventually lead to improved prevention of AKI, mitigation of injury when AKI occurs, and enhanced recovery in patients who sustain AKI. The development of advanced clinical prediction scores for AKI, new imaging techniques, and novel biomarkers for early detection of AKI provides new tools toward these ends.

Acute Kidney Injury in the Surgical Patient

Perioperative acute kidney injury (AKI) is a common, morbid, and costly surgical complication. Current efforts to understand and manage AKI in surgical patients focus on prevention, mitigation of further injury when AKI has occurred, treatment of associated conditions, and facilitation of renal recovery. Lesser severity AKI is now understood to be much more common, and more morbid, than was previously thought. The ability to detect AKI within hours of onset would be helpful in protecting the kidney and in preserving renal function, and several imaging and biomarker modalities are currently being evaluated.