Table of Contents  
Year : 2017  |  Volume : 11  |  Issue : 4  |  Page : 327-331

Association of acute kidney injury defined with the AKIN criteria and poor outcome in acute respiratory distress syndrome patients

Department of Critical Care Medicine, Cairo University, Cairo, Egypt

Date of Submission08-Feb-2017
Date of Acceptance09-Mar-2017
Date of Web Publication3-Nov-2017

Correspondence Address:
Mohamed H Saleh
Critical Care Medicine Lecturer, Cairo University
Login to access the Email id

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/1687-8426.203796

Rights and Permissions

Background Few studies have reported the deleterious association between acute respiratory distress syndrome (ARDS) and acute kidney injury (AKI). We aimed to evaluate the association of AKI and poor outcome in ARDS patients and whether this association is related to fluid overload or not.
Patients and methods Sixty-four patients diagnosed with ARDS and had been mechanically ventilated were enrolled. AKI was diagnosed using the Acute Kidney Injury Network criteria. Patients were stratified into two groups according to the degree of renal impairment. All data were statistically analyzed.
Results The mean age of the studied patients was 47.23±10.12 years; 33 (51.6%) were men. In group 2, the follow-up Lung Injury Severity Score and length of hospital stay were significantly higher compared with group 1: 3.33±0.74 points and 19.11±6.37 days versus 2.84±0.57 points and 12.38±4.21 days (P=0.004 and <0.001, respectively). Also, they had higher need to use vasoactive (VA) agents, 21 (55.3%) versus 6 (23.1%) patients, and spent more days on mechanical ventilation, 14.18±4.59 versus 8.51±3.77 (P=0.019 and <0.001, respectively). In-patient mortality was higher in group 2 compared with group 1: 18 (66.7%) versus 6 (23.1%) (P=0.019). In-patient mortality was significantly correlated with the need to use VA agents and higher cumulative fluid balance (R=0.394 and 0.24, P=0.001 and 0.05, respectively). The need to use VA agents was the only independent predictor of mortality (odds ratio=4.18, P=0.022).
Conclusion AKI as defined on the basis of the Acute Kidney Injury Network criteria is associated with poor outcome in ARDS patients.

Keywords: acute kidney injury, Acute Kidney Injury Network criteria, acute respiratory distress syndrome

How to cite this article:
Saleh MH, Elghonemi MO. Association of acute kidney injury defined with the AKIN criteria and poor outcome in acute respiratory distress syndrome patients. Egypt J Bronchol 2017;11:327-31

How to cite this URL:
Saleh MH, Elghonemi MO. Association of acute kidney injury defined with the AKIN criteria and poor outcome in acute respiratory distress syndrome patients. Egypt J Bronchol [serial online] 2017 [cited 2018 Oct 22];11:327-31. Available from:

  Introduction Top

Acute respiratory distress syndrome (ARDS) is a leading cause of mortality and morbidity in critically ill patients [1]. The main pathological changes in ARDS patients are increased capillary permeability that lead to accumulation of proteinaceous fluid in the pulmonary interstitum [2].

Many studies have reported the possible deleterious interactions between lung and kidney dysfunctions [3]. Experimental studies suggest that acute kidney injury (AKI) with subsequent activation of proinflammatory and proapoptotic pathways because of renal ischemia/reperfusion may be associated with an increased risk of acute lung injury. [3],[4],[5],[6],[7]. Moreover, several lines of evidence point to the adverse effects of ARDS and mechanical ventilation on renal function through three main mechanisms. First, positive-pressure ventilation may reduce cardiac output and increase central venous pressure, with a subsequent decrease of renal blood flow, free water clearance, and glomerular filtration rate [8]. In addition, hypoxia and hypercarbia may affect renal vascular resistance, renal perfusion, and diuresis [9]. Finally, the release of inflammatory cytokines following ARDS may lead to further systemic inflammation [10],[11]. In 2005, a new classification of AKI was proposed by the Acute Kidney Injury Network (AKIN) working group composed of nephrologists, critical care physicians, and other physicians specialized in AKI. The AKIN classification was published in March 2007 [12].

The aim of this study is to evaluate the influence of AKI defined by the AKIN criteria on the outcome of ARDS patients in an ICU and to determine whether this influence is related to fluid overload or not.

  Patients and methods Top

This study was a prospective observational study carried out on 64 patients admitted to the Critical Care Department of Cairo University and diagnosed with ARDS from March to December 2014. The study has been approved by our local ethical committee. According to the Berlin Criteria, ARDS was defined by timing (within 1 week of clinical insult or onset of respiratory symptoms); radiographic changes (bilateral opacities not fully explained by effusions, consolidation, or atelectasis); origin of edema (not fully explained by cardiac failure or fluid overload); and severity on the basis of the PaO2/FiO2 ratio on 5 cm of continuous positive airway pressure [13]. All patients underwent a full clinical examination and laboratory investigation including assessments of blood gases and lactate levels. Acute Physiology and Chronic Health Evaluation II (APACHE II) and Lung Injury Severity (LIS) Scores were calculated upon admission. The LIS score was reassessed 1 week after admission for all patients.

All patients received mechanical ventilation through a commercially available ventilator (Puritan-Bennett=840) in the volume-controlled mode. Tidal volume was set to be 6–8 ml/kg. Predicted body weight in kg was calculated from the following formula: 2.3(height (inches)-60)+45.5 for women or 50 for men. The respiratory rate was set up to 35 breaths/min to deliver the expected minute ventilation requirement (generally, 7–9 l/min). Positive end-expiratory pressure and FiO2 were set to maintain an arterial oxygen saturation of 88–95%. Ventilator adjustments were made to maintain the plateau pressure (measured during an inspiratory hold of 0.5 s) less than 30 cmH2O and to maintain accepted blood gas parameters with permissive hypercapnea. If plateau pressures remained high after following the above protocol, tidal volume was further reduced to as low as 4 ml/kg by 1 ml/kg stepwise increments. All patients were lightly sedated to minimize ventilator–patient dyssynchrony.

During ICU stay, the degree of renal impairment was assessed using the AKIN criteria and categorized into grades 1, 2, and 3 [14]. Patients were stratified according to the degree of renal impairment into two groups:

Group 1 included patients with normal or near normal kidney function (AKIN 0,1).

Group 2 included patients with significantly impaired kidney function (AKIN 2,3).

Both groups were compared in terms of their outcomes. Patients who died within 24 h of admission, had a suggestive history or clinical evidence of congestive heart failure, or were younger than 18 years of age were excluded.

Statistical methods

Data were statistically described as mean±SD, median and range, or frequencies (number of cases) and percentages when appropriate. Comparison of numerical variables between the study groups was performed using the Student t-test for independent samples. To compare categorical data, the χ2-test was performed. The exact test was used when the expected frequency was less than 5. The correlation between various variables was assessed using the Spearman rank correlation equation. P values less than 0.05 were considered statistically significant. All statistical calculations were carried out using the computer program statistical package for the social science (SPSS Inc., Chicago, Illinois, USA), release 15 for Microsoft Windows (2006).

  Results Top

The mean age of the studied patients was 47.23±10.12 years; 33 (51.6%) were men. The mean PaO2/FiO2, and LIS score on admission were 169.95±31and 3.06±0.54, respectively. Apart from cumulative fluid balance, which was higher in group 2 compared with group 1 (2.8±3.1 vs. −1.2±2.88 l, P=0.02), patients in both groups had comparable general characteristic data ([Table 1]). In group 2 patients, 15 (23.3%) and 12 (18.7%) patients had AKIN grades 2 and 3, respectively. Patients in group 2 had worse outcome parameters compared with those in group 1 as the follow-up LIS and length of hospital stay were significantly higher in group 2 compared with group 1 patients: 3.3±0.7 points and 19.1±6.3 days versus 2.84±0.5 points and 12.3±4.1 days (P=0.004 and 0.001, respectively). Also, they had a higher need to use vasoactive (VA) agents, 21 (77.7%) patients versus 17 (45.9%) patients, and spent more days on mechanical ventilation, 14.1±4.5 versus 8.5±3.7 (P=0.019 and <0.001, respectively) ([Table 2]).
Table 1 General characteristics of the studied patients

Click here to view
Table 2 Comparison between two studied groups in different outcome parameters

Click here to view

In the studied patients, in-patient mortality occurred in 30 (46.9%) patients, and it was significantly higher in the patients in group 2: 18 (66.7%) versus 12 (32.4%) (P=0.019). ([Table 3]) shows a comparison of surviving and nonsurviving patients. Although it was not significant, we noted that the cumulative fluid balance was more positive in nonsurviving patients as opposed to a more negative fluid balance in those who survived. Spearman’s correlation showed that in-patient mortality was significantly correlated with the need to use VA agents and cumulative fluid balance, but not admission/follow-up LIS or length of hospital stay ([Table 4]).
Table 3 Comparison between survivors and nonsurvivors in their general characteristics

Click here to view
Table 4 Correlation between in-patient mortality and other variables

Click here to view

Univariate regression analysis showed that positive cumulative fluid balance is an independent predictor of higher follow-up LIS and length of hospital stay, but not for the need to use VA agents or mortality ([Table 5]).
Table 5 Cumulative fluid balance as a predictor of outcome

Click here to view

In multivariate analysis, AKIN grade was not an independent predictor of in-patient mortality (odds ratio=0.797 and P=0.549). The need to use VA agents was the only independent predictor of mortality in our cohort (odds ratio=4.18 and P=0.022).

  Discussion Top

There is growing evidence pointing to deleterious interactions between lung dysfunction and renal impairment in critically ill patients [3]. This study found a higher incidence of AKI in ARDS patients and its contribution toward poor outcome in these patients as our results indicate that 42% of ARDS patients developed significant renal impairment, that is, AKIN grades 2 and 3 during their hospital stay. Also, development of significant renal impairment was associated with increased mortality, in addition to other poor outcome parameters such as length of hospital stay, need to use VA agents, and number of days on mechanical ventilation. Multivariate regression analysis showed that AKI was not an independent predictor of mortality in our cohort.

The reciprocal risk of AKI and lung dysfunction in critically ill patients was similarly reported by Clemens et al. [15]. Unlike our study, they also reported that both AKI and ARDS are independent risks for subsequent death. This can probably be attributed to the different type of patients in their study; they studied burn patients.

The ARDSNet investigators [10] and Darmon et al. [16] reported an increased risk of development of AKI in ARDS patients. Similarly, many investigators reported that biotrauma induced by mechanical ventilation with the subsequent release of inflammatory cytokines not only affects the lung but also leads to further systemic inflammation with subsequent kidney and other organ dysfunction [10],[11],[17]. However, these studies did not clearly evaluate the influence of development of AKI on the patients’ outcome.

A recent meta-analysis suggested that both ARDS and mechanical ventilation were associated with a three-fold increase in the risk of AKI [18]. The studies included in this analysis were focused on specific types of patients such as trauma [19], postlung transplant [20], malignant [21], and advanced liver cell failure patients [22]. Thus, the general applicability of the findings is unclear.

In our results, positive cumulative fluid balance was an independent predictor of poor outcome parameters such as follow-up LIS score and length of hospital stay, but not in-patient mortality. This observation may postulate the possible mechanism of the association between AKI and poor outcome in our cohort. We believe that this observation could have therapeutic implications in the management of AKI in ARDS patients. In line with these results, a randomized, multicenter study [2] evaluated a strategy of fluid restriction in ARDS patients. Unlike our study, they excluded patients with renal failure. However, their results similarly showed that a conservative strategy significantly improved oxygenation in patients and decreased the number of days with mechanical ventilation, but did not influence mortality at 60 days. However, Prowle et al. [23] limiting the beneficial effect of fluid restriction in ARDS patients to whom the pulmonary edema is more pronounced but not in less severe form of lung injury. Moreover, they reported that fluid restriction may lead to tissue hypoperfusion with and renal injury. Seethala et al. [24] reported that higher volume of early fluid administration was associated with the development of ARDS, meaning that higher cumulative fluid balance is not only a predictor of outcome in ARDS patients but could also be a causative factor in septic patients.

Our results also showed that the need to use VA agents was the only independent predictor of mortality in our cohort. This confirms previous study results of Boyle et al. [25], who reported that the use of vasopressors was one of the predictors of mortality in their cohort.

  Conclusion Top

AKI is associated with poor outcome in ARDS patients. Higher cumulative balance with subsequent volume overload could possibly be a poor prognostic factor.

In addition to a small sample size, this study had many limitations. As this was an observational study, we did not evaluate the influence of different AKI therapeutic modalities on the outcome in ARDS patients. Also, the value of early renal replacement therapy in these patients was not assessed.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Rubenfeld GD, Caldwell E, Peabody E, Weaver J, Martin DP, Neff M et al. Incidence and outcomes of acute lung injury. N Engl J Med 2005; 353:1685–1693.  Back to cited text no. 1
National Heart, Lung, and Blood Institute Acute Respiratory Distress Syndrome Clinical Trials Network, Wiedemann HP, Wheeler AP, Bernard GR, Thompson BT, Hayden D et al. Comparison of two fluid-management strategies in acute lung injury. N Engl J Med 2006; 354:2564–2575.  Back to cited text no. 2
Li X, Hassoun HT, Santora R, Rabb H. Organ crosstalk: the role of the kidney. Curr Opin Crit Care 2009; 15:481–487.  Back to cited text no. 3
Kramer AA, Postler G, Salhab KF, Mendez C, Carey LC, Rabb H. Renal ischemia/reperfusion leads to macrophage-mediated increase in pulmonary vascular permeability. Kidney Int 1999; 55:2362–2367.  Back to cited text no. 4
Deng J, Hu X, Yuen PST, Star RA. Alpha-melanocyte-stimulating hormone inhibits lung injury after renal ischemia/reperfusion. Am J Respir Crit Care Med 2004; 169:749–756.  Back to cited text no. 5
Hassoun HT, Lie ML, Grigoryev DN, Liu M, Tuder RM, Rabb H. Kidney ischemia-reperfusion injury induces caspase-dependent pulmonary apoptosis. Am J Physiol Renal Physiol 2009; 297:125–137.  Back to cited text no. 6
Hassoun HT, Grigoryev DN, Lie ML, Liu M, Cheadle C, Tuder RM, Rabb H. Ischemic acute kidney injury induces a distant organ functional and genomic response distinguishable from bilateral nephrectomy. Am J Physiol Renal Physiol 2007; 293:30–40.  Back to cited text no. 7
Farge D, de la Coussaye JE, Beloucif S, Fratacci MD, Payen DM. Interactions between hemodynamic and hormonal modifications during PEEP-induced antidiuresis and antinatriuresis. Chest 1995; 107:1095–1100.  Back to cited text no. 8
Darmon M, Schortgen F, Leon R, Moutereau S, Mayaux J, di Marco F et al. Impact of mild hypoxemia on renal function and renal resistive index during mechanical ventilation. Intensive Care Med 2009; 35:1031–1038.  Back to cited text no. 9
Liu KD, Glidden DV, Eisner MD, Parsons PE, Ware LB, Wheeler A et al. Predictive and pathogenetic value of plasma biomarkers for acute kidney injury in patients with acute lung injury. Crit Care Med 2007; 35:2755–2761.  Back to cited text no. 10
The Acute Respiratory Distress Syndrome Network. Ventilation with lower tidal volumes as compared with traditional tidal volumes for acute lung injury and the acute respiratory distress syndrome. N Engl J Med 2000; 342:1301–1308.  Back to cited text no. 11
Mehta RL, Kellum JA, Shah SV, Molitoris BA, Ronco C, Warnock DC et al. Acute Kidney Injury Network: report of an initiative to improve outcomes in acute kidney injury. Crit Care 2007; 11:R31.  Back to cited text no. 12
ARDS Definition Task Force, Ranieri VM, Rubenfeld GD, Thompson BT, Ferguson ND, Caldwell E et al. Acute respiratory distress syndrome: the Berlin Definition. JAMA 2012' 307:2526–2533.  Back to cited text no. 13
De Arujo A, Alvares da Silva MR. Akin criteria as a predictor of mortality in cirrhotic patients after spontaneous bacterial peritonitis. Ann Hepatol 2014; 13:390–395.  Back to cited text no. 14
Clemens MS, Stewart IJ, Sosnov JA, Howard JT, Belenkiy SM, Sine CR et al. Reciprocal risk of acute kidney injury and acute respiratory distress syndrome in critically ill burn patients. Crit Care Med 2016; 44:915–922.  Back to cited text no. 15
Darmon M, Clec’h C, Adrie C, Argaud L, Allaouchiche B, Azoulay E et al. Acute respiratory distress syndrome and risk of AKI among critically ill patients. Clin J Am Soc Nephrol 2014; 9:1347–1353.  Back to cited text no. 16
Ranieri VM, Giunta F, Suter PM, Slutsky AS. Mechanical ventilation as a mediator of multisystem organ failure in acute respiratory distress syndrome. JAMA 2000; 284:43–44.  Back to cited text no. 17
Van den Akker JP, Egal M, Groeneveld JA. Invasive mechanical ventilation as a risk factor for acute kidney injury in the critically ill: a systematic review and meta-analysis. Crit Care 2013; 17:R98.  Back to cited text no. 18
Vivino G, Antonelli M, Moro ML, Cottini F, Conti G, Bufi M et al. Risk factors for acute renal failure in trauma patients. Intensive Care Med 1998; 24:808–814.  Back to cited text no. 19
Rocha PN, Rocha AT, Palmer SM, Davis RD, Smith SR. Acute renal failure after lung transplantation: incidence, predictors and impact on perioperative morbidity and mortality. Am J Transplant 2005; 5:1469–1476.  Back to cited text no. 20
Lahoti A, Kantarjian H, Salahudeen AK, Ravandi F, Cortes JE, Faderl S et al. Predictors and outcome of acute kidney injury in patients with acute myelogenous leukemia or high-risk myelodysplastic syndrome. Cancer 2010; 116:4063–4068.  Back to cited text no. 21
O’Riordan A, Brummell Z, Sizer E, Auzinger G, Heaton N, O’Grady JG et al. Acute kidney injury in patients admitted to a liver intensive therapy unit with paracetamol-induced hepatotoxicity. Nephrol Dial Transplant 2011; 26:3501–3508.  Back to cited text no. 22
Prowle JR, Kirwan CJ, Bellomo R. Fluid management for the prevention and attenuation of acute kidney injury. Nat Rev Nephrol 2014; 10:37–47.  Back to cited text no. 23
Seethala RR, Hou CC, Aisiku IP, Frendl G, Park PK, Mikkelsen ME et al. Early risk factors and the role of fluid administration in developing acute respiratory distress syndrome in septic patients. Ann Intensive Care 2017; 7:11.  Back to cited text no. 24
Boyle AJ, di Gangi S, Hamid UI, Mottram LJ, McNamee L, White G, et al. Aspirin therapy in patients with acute respiratory distress syndrome (ARDS) is associated with reduced intensive care unit mortality: a prospective analysis. Crit Care 2015; 19:109.  Back to cited text no. 25


  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]


Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
Access Statistics
Email Alert *
Add to My List *
* Registration required (free)

  In this article
Patients and methods
Article Tables

 Article Access Statistics
    PDF Downloaded77    
    Comments [Add]    

Recommend this journal