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Renal Doppler in the management of the acute kidney injury in intensive care unit
Journal of Critical Care (2013) 28, 313–314
Renal Doppler in the management of the acute kidney injury in intensive care unit We read with great interest the study of Dewitte et al [1] assessing that fractional excretion of urea less than 40% is a good urinary index in differentiating transient from persistent acute kidney injury (AKI) in intensive care unit (ICU) patients. We agree with the authors: the clinical goal is to diagnose transient AKI early before its transition into tubular functional damage. Its prompt recognition supports the goaldirected reestablishment of renal perfusion and the development of preventive strategies to attenuate acute tubular necrosis [2]. Fractional excretion of urea is based on biological measurements, and this urinary urea–based index does not allow a real running time assessment. In the modern era of ultrasonography (US), the Doppler US can be used in the ICU to assess renal perfusion by calculating the resistive renal index (RRI) [3]. Preliminary reports suggest that Doppler-calculated RRI is a promising tool for predicting the reversibility of AKI in critically ill patients. In a study conducted in 65 subjects older than 60 years undergoing elective heart surgery with cardiopulmonary bypass, RRI greater than 0.74 in the postoperative period predicted delayed AKI with high sensitivity and specificity (0.85 and 0.94, respectively) [4]. Moreover, Lerrolle et al [5] showed that RRI on the first day of septic shock predicted acute renal failure on day 5: among 35 medical critical patients, RRI was higher in the 18 patients with acute renal failure (0.77 ± 0.08 vs 0.68 ± 0.08, P b .001). Darmon et al [2] have confirmed these results: an increased RRI greater than 0.795 predicted persistent AKI, with 82% sensitivity and 92% specificity in critically patients who required mechanical ventilation. This technique has also been demonstrated to be useful in the field of nephrology since Radermarcher et al [6] reported that a high RRI value was predictive of poor long-term allograft survival in renal transplant. Finally, RRI is a relevant end point in the hemodynamic management of septic shock, with a great therapeutic impact: in 11 patients with septic shock, Deruddre et al [7] demonstrated that RRI significantly decreased from 0.75 ± 0.07 to 0.71 ± 0.06, when mean arterial pressure was increased from 65 to 75 mm Hg, with a significant increasing urinary output. 0883-9441/$ – see front matter © 2013 Elsevier Inc. All rights reserved.
Beyond its ability to predict the reversibility of AKI, Doppler RRI use offers several advantages: rapidity (a critical advantage in hemodynamic evaluation), portability (the small size of these devices made them fully suitable for the ICU and the emergency department), real-time imaging, high feasibility (the kidney can almost always be visualized), simplicity, and ability to easily perform dynamic and repeated assessments of the renal circulation at the bedside. To conclude, we think that US is a decisive method for the initial assessment of renal perfusion in ICU patients. We would like to know if the authors may be based on their experience could precise their practical point of view on the use of renal Doppler US in AKI diagnosis in the ICU. Schaal Jean-Vivien MD Emergency and Intensive Care Department Military Teaching Hospital Percy 92140, Clamart, France Pasquier Pierre MD Renner Julie MD Jarrassier Audrey MD Salvadori Alexandre MD Mérat Stéphane MD Emergency and Intensive Care Department Military Teaching Hospital Bégin 69 avenue de Paris, 94163 Saint-Mandé, France http://dx.doi.org/10.1016/j.jcrc.2012.12.005
References [1] Dewitte A, Biais M, Petit L, et al. Fractional excretion of urea as a diagnostic index in acute kidney injury in intensive care patients. J Crit Care 2012;27:505-10. [2] Darmon M, Schortgen F, Vargas F, et al. Diagnostic accuracy of Doppler renal resistive index for reversibility of acute kidney injury in critically ill patients. Intensive Care Med 2011;37:68-76. [3] Barozzi L, Valentino M, Santoro A, et al. Renal ultrasonography in critically ill patients. Crit Care Med 2007;35:S198-205. [4] Bossard G, Bourgoin P, Corbeau JJ, et al. Early detection of postoperative acute kidney injury by Doppler renal resistive index in cardiac surgery with cardiopulmonary bypass. Br J Anaesth 2011;107:891-8.
314 [5] Lerolle N, Guerot E, Faisy C, et al. Renal failure in septic shock: predictive value of Doppler-based renal arterial resistive index. Intensive Care Med 2006;32:1553-9. [6] Radermacher J, Mengel M, Ellis S, et al. The renal arterial resistance index and renal allograft survival. N Engl J Med 2003;349:115-24. [7] Deruddre S, Cheisson G, Mazoit JX, et al. Renal arterial resistance in septic shock: effects of increasing mean arterial pressure with norepinephrine on the renal resistive index assessed with Doppler ultrasonography. Intensive Care Med 2007;33:1557-62.
Renal Doppler in the management of the acute kidney injury in intensive care unit Acute kidney injury (AKI) is a dynamic process that evolves from an early reversible condition to an established disease and leads to sustained renal impairment, cell death, and delayed renal recovery. Delay in the diagnosis of AKI using conventional biomarkers such as urine output and serum creatinine remains clearly one of the important obstacles in applying effective early interventions. In recent years, many urinary and serum proteins have been investigated as possible early markers of kidney damage, but to date, none of them is perfect, especially for septic patients. In addition, despite our results in nonselected critically ill patients [1], urine biochemical tests and derived indices recently fail to reliably predict worsening AKI, need for renal replacement therapy, and mortality and show relatively poor association with urine and plasma Neutrophil Gelatinase Associated Lipocalin [2]. Renal resistive index or renal vascular index (RVI), a less definite term recommended by N. Lerolle [3], allows effectively a rapid and simple estimation of renal vascular resistance at the bedside by Doppler ultrasonography. However, precision of measurements in comparison with the Doppler differences seen in patients remains the main limitations when determining RVI, and its interpretation is difficult in clinical practice. In a recent study testing the relationship between RVI and mean arterial pressure, we only found a poor correlation in septic and critically ill patients without AKI, suggesting that determinants of RVI are numerous [4]. Increased RVI may be associated with low renal perfusion pressure or low oxygenation levels in patients without AKI but may also be associated with sustained renal injury [5–7]. Thus, a single value in septic critically ill patients should be interpreted carefully before concluding that there is renal injury or estimating optimal mean arterial pressure. As recently admitted critically ill patients surely suffer from kidney damage at different intensities, we believe that
Letters/Editorials the usefulness of RVI lies in its variations after early management. To adapt our practice, the clinical goal could be to rapidly identify patients with renal recovery capabilities or sufficient renal functional reserve. Patients not responding to an early goal-directed therapy, recognized by a persistent increased in Doppler RVI (or biomarkers of kidney damage), would for instance not tolerate a chloride-liberal intravenous fluid administration strategy as recently suggested [8]. Of course, the use of RVI this way in clinical practice needs to be validated in future AKI studies. Antoine Dewitte MD CHU de Bordeaux Service d'Anesthésie-Réanimation II F-33000 Bordeaux, France Univ. Bordeaux Bioingénierie tissulaire, U1026 F-33000 Bordeaux, France E-mail address: [email protected] http://dx.doi.org/10.1016/j.jcrc.2013.01.003
References [1] Dewitte A, Biais M, Petit L, et al. Fractional excretion of urea as a diagnostic index in acute kidney injury in intensive care patients. J Crit Care 2012;27:505-10. [2] Bagshaw SM, Bennett M, Devarajan P, et al. Urine biochemistry in septic and non-septic acute kidney injury: a prospective observational study. J Crit Care 2012. doi:10.1016/j.jcrc.2012.10.007 [Epub ahead of print]. [3] Lerolle N. Please don't call me RI anymore; I may not be the one you think I am! Crit Care 2012;16:174. [4] Dewitte A, Coquin J, Meyssignac B, et al. Doppler resistive index to reflect regulation of renal vascular tone during sepsis and acute kidney injury. Crit Care 2012;16:R165. [5] Darmon M, Schortgen F, Leon R, et al. Impact of mild hypoxemia on renal function and renal resistive index during mechanical ventilation. Intensive Care Med 2009;35:1031-8. [6] Darmon M, Schortgen F, Vargas F, et al. Diagnostic accuracy of Doppler renal resistive index for reversibility of acute kidney injury in critically ill patients. Intensive Care Med 2011;37:68-76. [7] Deruddre S, Cheisson G, Mazoit JX, et al. Renal arterial resistance in septic shock: effects of increasing mean arterial pressure with norepinephrine on the renal resistive index assessed with Doppler ultrasonography. Intensive Care Med 2007;33:1557-62. [8] Yunos NM, Bellomo R, Hegarty C, et al. Association between a chlorideliberal vs chloride-restrictive intravenous fluid administration strategy and kidney injury in critically ill adults. JAMA 2012;308:1566-72.
Renal Doppler in the management of the acute kidney injury in intensive care unit We read with great interest the study of Dewitte et al [1] assessing that fractional excretion of urea less than 40% is a good urinary index in differentiating transient from persistent acute kidney injury (AKI) in intensive care unit (ICU) patients. We agree with the authors: the clinical goal is to diagnose transient AKI early before its transition into tubular functional damage. Its prompt recognition supports the goaldirected reestablishment of renal perfusion and the development of preventive strategies to attenuate acute tubular necrosis [2]. Fractional excretion of urea is based on biological measurements, and this urinary urea–based index does not allow a real running time assessment. In the modern era of ultrasonography (US), the Doppler US can be used in the ICU to assess renal perfusion by calculating the resistive renal index (RRI) [3]. Preliminary reports suggest that Doppler-calculated RRI is a promising tool for predicting the reversibility of AKI in critically ill patients. In a study conducted in 65 subjects older than 60 years undergoing elective heart surgery with cardiopulmonary bypass, RRI greater than 0.74 in the postoperative period predicted delayed AKI with high sensitivity and specificity (0.85 and 0.94, respectively) [4]. Moreover, Lerrolle et al [5] showed that RRI on the first day of septic shock predicted acute renal failure on day 5: among 35 medical critical patients, RRI was higher in the 18 patients with acute renal failure (0.77 ± 0.08 vs 0.68 ± 0.08, P b .001). Darmon et al [2] have confirmed these results: an increased RRI greater than 0.795 predicted persistent AKI, with 82% sensitivity and 92% specificity in critically patients who required mechanical ventilation. This technique has also been demonstrated to be useful in the field of nephrology since Radermarcher et al [6] reported that a high RRI value was predictive of poor long-term allograft survival in renal transplant. Finally, RRI is a relevant end point in the hemodynamic management of septic shock, with a great therapeutic impact: in 11 patients with septic shock, Deruddre et al [7] demonstrated that RRI significantly decreased from 0.75 ± 0.07 to 0.71 ± 0.06, when mean arterial pressure was increased from 65 to 75 mm Hg, with a significant increasing urinary output. 0883-9441/$ – see front matter © 2013 Elsevier Inc. All rights reserved.
Beyond its ability to predict the reversibility of AKI, Doppler RRI use offers several advantages: rapidity (a critical advantage in hemodynamic evaluation), portability (the small size of these devices made them fully suitable for the ICU and the emergency department), real-time imaging, high feasibility (the kidney can almost always be visualized), simplicity, and ability to easily perform dynamic and repeated assessments of the renal circulation at the bedside. To conclude, we think that US is a decisive method for the initial assessment of renal perfusion in ICU patients. We would like to know if the authors may be based on their experience could precise their practical point of view on the use of renal Doppler US in AKI diagnosis in the ICU. Schaal Jean-Vivien MD Emergency and Intensive Care Department Military Teaching Hospital Percy 92140, Clamart, France Pasquier Pierre MD Renner Julie MD Jarrassier Audrey MD Salvadori Alexandre MD Mérat Stéphane MD Emergency and Intensive Care Department Military Teaching Hospital Bégin 69 avenue de Paris, 94163 Saint-Mandé, France http://dx.doi.org/10.1016/j.jcrc.2012.12.005
References [1] Dewitte A, Biais M, Petit L, et al. Fractional excretion of urea as a diagnostic index in acute kidney injury in intensive care patients. J Crit Care 2012;27:505-10. [2] Darmon M, Schortgen F, Vargas F, et al. Diagnostic accuracy of Doppler renal resistive index for reversibility of acute kidney injury in critically ill patients. Intensive Care Med 2011;37:68-76. [3] Barozzi L, Valentino M, Santoro A, et al. Renal ultrasonography in critically ill patients. Crit Care Med 2007;35:S198-205. [4] Bossard G, Bourgoin P, Corbeau JJ, et al. Early detection of postoperative acute kidney injury by Doppler renal resistive index in cardiac surgery with cardiopulmonary bypass. Br J Anaesth 2011;107:891-8.
314 [5] Lerolle N, Guerot E, Faisy C, et al. Renal failure in septic shock: predictive value of Doppler-based renal arterial resistive index. Intensive Care Med 2006;32:1553-9. [6] Radermacher J, Mengel M, Ellis S, et al. The renal arterial resistance index and renal allograft survival. N Engl J Med 2003;349:115-24. [7] Deruddre S, Cheisson G, Mazoit JX, et al. Renal arterial resistance in septic shock: effects of increasing mean arterial pressure with norepinephrine on the renal resistive index assessed with Doppler ultrasonography. Intensive Care Med 2007;33:1557-62.
Renal Doppler in the management of the acute kidney injury in intensive care unit Acute kidney injury (AKI) is a dynamic process that evolves from an early reversible condition to an established disease and leads to sustained renal impairment, cell death, and delayed renal recovery. Delay in the diagnosis of AKI using conventional biomarkers such as urine output and serum creatinine remains clearly one of the important obstacles in applying effective early interventions. In recent years, many urinary and serum proteins have been investigated as possible early markers of kidney damage, but to date, none of them is perfect, especially for septic patients. In addition, despite our results in nonselected critically ill patients [1], urine biochemical tests and derived indices recently fail to reliably predict worsening AKI, need for renal replacement therapy, and mortality and show relatively poor association with urine and plasma Neutrophil Gelatinase Associated Lipocalin [2]. Renal resistive index or renal vascular index (RVI), a less definite term recommended by N. Lerolle [3], allows effectively a rapid and simple estimation of renal vascular resistance at the bedside by Doppler ultrasonography. However, precision of measurements in comparison with the Doppler differences seen in patients remains the main limitations when determining RVI, and its interpretation is difficult in clinical practice. In a recent study testing the relationship between RVI and mean arterial pressure, we only found a poor correlation in septic and critically ill patients without AKI, suggesting that determinants of RVI are numerous [4]. Increased RVI may be associated with low renal perfusion pressure or low oxygenation levels in patients without AKI but may also be associated with sustained renal injury [5–7]. Thus, a single value in septic critically ill patients should be interpreted carefully before concluding that there is renal injury or estimating optimal mean arterial pressure. As recently admitted critically ill patients surely suffer from kidney damage at different intensities, we believe that
Letters/Editorials the usefulness of RVI lies in its variations after early management. To adapt our practice, the clinical goal could be to rapidly identify patients with renal recovery capabilities or sufficient renal functional reserve. Patients not responding to an early goal-directed therapy, recognized by a persistent increased in Doppler RVI (or biomarkers of kidney damage), would for instance not tolerate a chloride-liberal intravenous fluid administration strategy as recently suggested [8]. Of course, the use of RVI this way in clinical practice needs to be validated in future AKI studies. Antoine Dewitte MD CHU de Bordeaux Service d'Anesthésie-Réanimation II F-33000 Bordeaux, France Univ. Bordeaux Bioingénierie tissulaire, U1026 F-33000 Bordeaux, France E-mail address: [email protected] http://dx.doi.org/10.1016/j.jcrc.2013.01.003
References [1] Dewitte A, Biais M, Petit L, et al. Fractional excretion of urea as a diagnostic index in acute kidney injury in intensive care patients. J Crit Care 2012;27:505-10. [2] Bagshaw SM, Bennett M, Devarajan P, et al. Urine biochemistry in septic and non-septic acute kidney injury: a prospective observational study. J Crit Care 2012. doi:10.1016/j.jcrc.2012.10.007 [Epub ahead of print]. [3] Lerolle N. Please don't call me RI anymore; I may not be the one you think I am! Crit Care 2012;16:174. [4] Dewitte A, Coquin J, Meyssignac B, et al. Doppler resistive index to reflect regulation of renal vascular tone during sepsis and acute kidney injury. Crit Care 2012;16:R165. [5] Darmon M, Schortgen F, Leon R, et al. Impact of mild hypoxemia on renal function and renal resistive index during mechanical ventilation. Intensive Care Med 2009;35:1031-8. [6] Darmon M, Schortgen F, Vargas F, et al. Diagnostic accuracy of Doppler renal resistive index for reversibility of acute kidney injury in critically ill patients. Intensive Care Med 2011;37:68-76. [7] Deruddre S, Cheisson G, Mazoit JX, et al. Renal arterial resistance in septic shock: effects of increasing mean arterial pressure with norepinephrine on the renal resistive index assessed with Doppler ultrasonography. Intensive Care Med 2007;33:1557-62. [8] Yunos NM, Bellomo R, Hegarty C, et al. Association between a chlorideliberal vs chloride-restrictive intravenous fluid administration strategy and kidney injury in critically ill adults. JAMA 2012;308:1566-72.