Quantified power Doppler as a predictor of delayed graft function after renal transplantation

Performance of resistive index and semi-quantitative power doppler ultrasound score in predicting acute kidney injury: A meta-analysis of prospective studies

This study aimed to assess the predictive value of the renal resistive index (RRI) and power Doppler ultrasound (PDU) on subsequent acute kidney injury (AKI) risk using a meta-analytic approach. We searched eligible studies in PubMed, EmBase, and the Cochrane library from inception until August 2021. The parameters included the sensitivity, specificity, positive and negative likelihood ratios (PLR and NLR), diagnostic odds ratio (DOR), and area under the receiver operating characteristic curves (AUC). Twenty-three prospective studies involving 2,400 patients were selected. The pooled sensitivity and specificity of the RRI and PDU were 0.76 and 0.79, and 0.64 and 0.90, respectively. The pooled PLR and NLR were 3.64 and 0.31, and 6.58 and 0.40 for the RRI and PDU, respectively. The DORs of the RRI and PDU for predicting AKI were 11.76, and 16.32, respectively. The AUCs of the RRI and PDU for predicting AKI were 0.83, and 0.86, respectively. There were no significant differences between the RRI and PDU for predicting AKI in terms of sensitivity, PLR, NLR, DOR, and AUC. The specificity of the RRI was lower than that of the PDU for predicting AKI. This study found that the predictive performance of the RRI and PDU from the Doppler ultrasound for AKI was similar, which need to be further verified based on the direct comparison results.

Renal echography for predicting acute kidney injury in critically ill patients: a prospective observational study

Objective

To investigate the diagnostic performances of renal resistive index (RRI) and semiquantitative power Doppler ultrasound (PDU) scores in predicting acute kidney injury (AKI) stage 3 in critically ill patients.

Methods

This prospective observational study included 148 patients (80 with reduced cardiac index [CI], 68 with maintained CI). RRI and semiquantitative PDU scores were measured within 6 h after intensive care unit admission. AKI was defined according to Kidney Disease Improving Global Outcomes criteria.

Results

A negative correlation between RRI and PDU score (r = −0.517, p < 0.001) and a positive correlation between PDU score and CI (r = 0.193, p = 0.019) were found, whereas RRI was not correlated with CI (r = 0.131, p = 0.121). The predictive value of RRI for AKI stage 3 was similar between CI-reduced (area under the curve [AUC] 0.761, 95% confidence interval 0.650–0.851, p < 0.001) and CI-maintained (AUC 0.786, 95% confidence interval 0.665–0.878, p < 0.001) patients. Conversely, PDU score could effectively predict AKI stage 3 in CI-reduced patients (AUC 0.872, 95% confidence interval 0.778–0.936, p < 0.001) but not in CI-maintained patients (AUC 0.669, 95% confidence interval 0.544–0.778, p = 0.071). The predictive value of PDU score for AKI stage 3 was statistically different between CI-reduced and CI-maintained patients (p = 0.021).

Conclusions

PDU scores could effectively predict AKI stage 3 in CI-reduced patients but not in CI-maintained patients. RRI is a poor predictor of AKI stage 3 in patients with reduced or maintained CI.

Semiquantitative Power Doppler Ultrasound Score to Predict Acute Kidney Injury in Patients With Sepsis or Cardiac Failure: A Prospective Observational Study

BACKGROUND

Diagnosing acute kidney injury (AKI) stage 3 in critically ill patients may help physicians in making treatment decisions. This diagnosis relies chiefly on urinary output and serum creatinine, which may be of limited value. This study aimed to explore the diagnostic performance of renal resistive index (RRI) and semiquantitative power Doppler ultrasound (PDU) scores in predicting AKI stage 3 in patients with sepsis or cardiac failure.

METHODS

This study is a prospective observational study that included 83 patients (40 with sepsis and 43 with cardiac failure). Renal resistive index and semiquantitative PDU scores were measured within 6 hours following admission to the intensive care unit. Acute kidney injury was defined according to the criteria set by Kidney Disease Improving Global Outcomes.

RESULTS

The predictive values of RRI (area under the curve [AUC] = 0.772, 95% confidence interval [CI] = 0.658-0.886) and PDU score (AUC = 0.780, 95% CI = 0.667-0.892) were similar in all patients. Power Doppler ultrasound score (AUC = 0.910, 95% CI = 0.815-1.000) could effectively predict AKI stage 3 in the cardiac failure subgroup, and the optimal cutoff for this parameter was ≤ 1 (sensitivity = 87.5%, specificity = 92.6%, Youden index = 0.801, accuracy in our population = 90.7%). However, PDU scores (AUC = 0.620, 95% CI = 0.425-0.814) could not predict AKI stage 3 in the sepsis subgroup. The predictive values of RRI for AKI stage 3 in the cardiac failure (AUC = 0.820, 95% CI = 0.666-0.974) and sepsis (AUC = 0.724, 95% CI = 0.538-0.910) subgroups were similar.

CONCLUSIONS

Power Doppler ultrasound scores could effectively predict AKI stage 3 in patients with cardiac failure but not in patients with sepsis. Renal resistive index is a poor predictor of AKI stage 3 in patients with sepsis or cardiac failure.

Increase in Serum Amylase and Resistive Index After Kidney Transplant Are Biomarkers of Delayed Graft Function

BACKGROUND

Both amylase and resistive index (RI) are routinely measured after kidney transplant and proposed as markers of delayed graft function (DGF).

MATERIAL AND METHODS

This retrospective cross-sectional study analyzed amylase and RI in 269 renal transplant recipients before and after transplantation, and at discharge. An increase above 20% of total amylase with/without RI>0.7 were evaluated as prognostic markers of DGF, hospitalization length and risk of rejection.

RESULTS

Serum amylase increase >20% was found in 103/269 (38.3%) patients who showed DGF (45.6% vs. 25.3%, p=0.001) and had lower estimated glomerular filtration rate compared to those with an amylase increase <20% (42.0±21.7 vs. 49.8±23.2 ml/min, p=0.007). The double condition consisting of concomitant amylase increase >20% and RI>0.7 was associated with higher DGF occurrence (65% vs. 24%, p<0.001), longer hospital stay, lower eGFR at discharge, and higher risk of rejection.

CONCLUSION

Patients with concomitant amylase increase >20% and RI>0.7 might require closer monitoring to diagnose DGF early and modify the therapeutic approach accordingly.

The predictive value of resistive index obtained by Doppler ultrasonography early after renal transplantation on long-term allograft function

DUSG is a useful diagnostic tool for the follow-up of renal transplant recipients. The measurement of intrarenal arterial RI by DUSG has been proven to predict short-term AF. The aim of the study was to evaluate the predictive value of DUSG performed during the early after RTx on long-term AF. Seventy patients were enrolled into study. DUSG was performed at third and seventh days after RTx. Patients were divided into two groups according to rate of recovery of graft function as patients with normal graft function and abnormal graft function. Although the RI values were correlated with the AF early after transplantation, they were not correlated with long-term AF. However, the rate of recovery of graft function at early period after RTx was correlated with creatinine level at first year and with glomerular filtration rate at first year and last visit. Although the RI has no predictive value for long-term AF, the rate of recovery of graft function at early post-transplantation period has predictive value for long-term AF; patients with higher RI values early after RTx should be followed carefully for the development of chronic allograft injury.

Emphysematous pyelonephritis in a transplanted kidney

Emphysematous pyelonephritis is a rare infection characterized by necrosis and gas accumulation in the renal parenchyma, adjacent tissues, and/or urinary collecting system. This entity is rarely reported in transplanted kidneys. Computed tomography imaging is necessary for diagnosis and risk classification. The authors described the case of a 58-year-old man who underwent a kidney transplant and presented sepsis from a urinary tract infection. An abdominal tomography showed some characteristics of emphysematous pyelonephritis associated with an abscess. A graft biopsy, performed 45 days after the transplant, failed to show signs of infection, and tubule-interstitial and vascular rejection were ruled out. The patient had a poor outcome, and a nephrectomy was needed, the pathological analysis of which yielded the diagnosis of chronic pyelonephritis with necrotizing papillitis. The patient became hemodynamically unstable and died. The authors highlight the current tomographic criteria for the diagnosis and treatment of emphysematous pyelonephritis and question the validity of accepting the same standards used to guide the treatment of patients without transplants, and call attention to the importance of the clinical status for the indication of nephrectomy in cases of emphysematous pyelonephritis.