Prevalence and Risk Factors of Acute Renal Failure after Cardiac Surgery in Southern Iran

This Article

Citations


Creative Commons License
Except where otherwise noted, this work is licensed under Creative Commons Attribution-NonCommercial 4.0 International License.

Article Information:


Group: 2010
Subgroup: Volume 12, Issue 6
Date: November 2010
Type: Original Article
Start Page: 636
End Page: 639

Authors:

  • M Janati
  • Department of Cardiovascular Surgery, Shiraz University of Medical Sciences, Shiraz, Fars, Iran
  • Y Mahmoodi
  • Department of Cardiology, Shiraz University of Medical Sciences, Shiraz, Fars, Iran
  • M Sharifian
  • Nephrology Urology Research Center, Shiraz University of Medical Sciences, Shiraz, Fars, Iran
  • S Amooee
  • Department of Obstetric and Gynecology, Shiraz University of Medical Sciences, Shiraz, Fars, Iran
  • J Kojuri
  • Department of Cardiology, Shiraz University of Medical Sciences, Shiraz, Fars, Iran
  • P Hekmati
  • Nephrology Urology Research Center, Shiraz University of Medical Sciences, Shiraz, Fars, Iran
  • AR Hamidian Jahromi
  • Renal Transplant Unit, St. Jeorge's Health Care, NHS Trust, London, UK
  • R Afshariani
  • Department of Public Health, School of Health and Nutrition, Shiraz University of Medical Sciences, Shiraz, Fars, Iran
  • J Roozbeh
  • Trauma Research Center, Rajaee Hospital, Nephrology Urology Research Center, Shiraz University of Medical Sciences, Shiraz, Fars, Iran

      Correspondence:

      Affiliation: Trauma Research Center, Rajaee Hospital, Nephrology Urology Research Center, Shiraz University of Medical Sciences
      City, Province: Shiraz, Fars
      Country: Iran
      Tel: +98-917-1114021
      Fax: +98-711-2349336
      E-mail: roozbehj@hotmail.com

Abstract:


Background: Acute renal failure requiring renal replacement therapy after cardiac surgery is still a cause of major morbidity and mortality worldwide. A number of risk factors for the development of acute renal injury after cardiac surgery have been previously described and based on these variables; several scoring algorithms were proposed. Predictive value of these algorithms in Iran is not described. This study investigates these risk factors among our patients in southern Iran.

 

Methods:  Two hundred and forty patients with normal kidney function who were candidates for cardiac surgery were enrolled and their baseline data were collected. Diabetes mellitus and age were selected as more controversial preoperative risk factors. Clamp and pump time were also selected as intra-operative risk factors and the type of operation was also considered as an independent risk factor. The patients were categorized in two groups including group 1:  Patients with post-operation normal kidney function and group 2: Patients with post-operation ARF. All patients were followed with serial measurement of serum creatinine post-operation.

 

Results: The incidence of acute renal failure was 11.25%. Mean age of the patients in group 1 was 54.24±15.88 and in group 2 was 52.85±18.20 years. There was not any significant correlation between duration of clamp time and post operation acute renal failure. Clamp time in group 1 was 51.49±11.88 and in group 2 was 53.48±13.40 min. Duration of pump time in group 1 was 63.31±12.56 min and in group 2 was 78.07±10.85 min. The difference was statistically significant. Forty two (20%) of the patients in group 1 and 13 (50%) in group 2 were diabetic.

 

Conclusion: Although several scoring algorithms are available for prediction of post-cardiac surgery complications, these can also be matched with our patients’ criteria enhancing their accuracy for our situation.

Keywords: Acute renal failure; Cardiac surgery; Risk factors

Manuscript Body:


Introduction

 

Acute renal failure (ARF) is considered as a serious complication of cardiac surgeries occurring in 1-30 % of patients and is associated with high morbidity and mortality. It is noted that 1-5% of these patients require renal replacement therapy.1-3 On the other hand, it has been reported that a transient kidney dysfunction (i.e. decline in glomerular filtration rate) is a regular consequence of extracorporeal circulation.4 ARF can arise from a variety of causes including intra-operation hypotension, postoperative cardiac complications that impair renal perfusion, atheroemboli and exposure to contrast media. A similar relationship between post-operation ARF and a modest rise in preoperative serum creatinine has been demonstrated in other studies.3-5

Other important independent risk factors for developing ARF are New York Heart Association functional class 4, emergency surgery, peripheral arterial disease, valve surgery and the need for preoperative intra-aortic balloon pump.1-6 Advanced age, left ventricular ejection fraction less than 50% and diabetes mellitus were shown as risk factors generally associated with increased risk of renal failure.

As patients undergoing cardiac surgery at Cardiac Surgery Ward of Faghihi Hospital affiliated to Shiraz University of Medical Sciences in Shiraz, southern Iran had commonly more than one of the above baseline risk factors, this study was performed to identify whether diabetes mellitus, type of operation, clamp and pump time and age are associated with increase in the risk of post-operation renal failure among our patients.

 

 

Materials and Methods

 

According to the definition of the Society of Thoracic Surgery (STS), ARF was defined as an increase of serum creatinine >2 mg/dl with a minimum doubling of the preoperative valve, or a new requirement for renal replacement therapy. Clamp time was defined as a period of time between clamping of ascending aorta till releasing the clamp of the aorta and pump time was considered as duration of cardiopulmonary bypass.

Two hundred and forty patients (192 male, 48 female) referred to Cardiac Surgery Ward of Faghihi Hospital affiliated to Shiraz University of Medical Sciences in Shiraz, southern Iran between April 2005 and April 2006 were enrolled. End stage renal disease patients under routine hemodialysis and renal transplant recipients were excluded.

The variables measured at the baseline included history of diabetes mellitus, age, sex, weight (Kg) and serum creatinine. Serial measurements of serum creatinine were undertaken for all patients in an interval of 24 hours in the post-operative period during ICU admission. Clamp time and pump time (minutes) were also considered as intra-operative risk factors, and the type of operation was considered as an independent risk factor too. All operations were categorized in five groups including coronary artery bypass graft, valvular replacement, correction of tetralogy of fallot, closure of VSD, ASD and others (Table 1).

 

 

Table 1: Type of operations.

Type of operation

No. (%)

Coronary artery  bypass graft

183 (76.25)

Valve replacement

Correction of TOF

Closure of ASD/VSD

Others

  16 (6.67)

    7 (2.91)

  16 (6.67)

  18 (7.50)

(TOF: Tetralogy of fallot, ASD: Atrial septal defect VSD: Ventricular septal defect)

 

 

Statistical analysis was performed using SPSS program (version 15, Chicago, IL, USA). Wilcoxon’s rank-sum and Mann-Whitney tests were used to compare continuous variables between patients with postoperative ARF. Pearson Chi-Square and student T tests were used to determine the relationship between the type of operation and post-operation renal failure. All continuous variables were expressed as mean±standard deviation. The results were considered statistically significant when p value was < 0.05.

 

 

Results

 

The mean age of patients was 54.08±16.12 years. The baseline plasma creatinine was 1.25±0.28 mg/dl. Demographic characteristics of the study group were shown in Table 2. The incidence of renal failure among our patients was 11.25%. Twenty seven patients (11.25%) developed acute renal failure according to the definition (Male: 20, female: 7). The patients were categorized in two groups including group 1: Patients with post-operation normal kidney function and group 2: Patients with post-operation ARF. Mean age of patients in group 1 was 54.24±15.88 and in group 2 was 52.85±18.20 years (p=0.805).

 

 

Table 2: Demographic characteristics of the patients.

Patients’ characteristics

No. (%) or

Mean±SD

Mean age (years)

54.08±16.12

Male

192 (80%)

Female

  48 (20%)

Weight (kg)

63.82±21.11

Baseline creatinine (mg/dl)

1.25±0.28

Diabetic patients

  55 (22.9%)

(Kilograms: kg, milligram: mg, deciliter: dl).

 

 

There was not any significant correlation between duration of clamp time and post-operation ARF. Clamp time in group 1 was 51.49±11.88 and in group 2 was 53.48±13.40 min (p=0.506). Duration of pump time in group 1 was 63.31±12.56 and in group 2 was 78.07±10.85 min. The difference was statistically significant (p=0.044). Forty two (20%) of the patients in group 1 and 13 (50%) patients in group 2 were diabetic (p=0.021) (Table 3).

 

 

Table 3: Relationships between variables of group 1 and group 2. 

Variables

Post-operation normal kidney function (Group 1)

Post-operation ARF (Group 2)

P value

Number

213

27

 

Male

172

20

 

Female

  41

  7

 

Age (years)

54.24±15.88

52.85±18.20

0.805

Diabetes mellitus

Pump time (min)

  42

63.31±12.56

13

78.07±10.85

0.021

0.044

Clamp time (min)

51.49±11.88

53.48±13.40

0.506

 

 

Discussion

 

Post-cardiac surgery ARF is still a leading cause of morbidity, mortality, prolonged hospitalization and increase in the health care cost.7 Thakar et al.,6 developed a clinical score to predict ARF after cardiac surgery. In a cohort study of 24,773 patients,1 Chertow et al. developed a risk stratification algorithm to estimate the risk and design interventions to improve the outcome. A large study designed a bed side tool for predicting the risk of postoperative ARF too.8 According to these studies, numerous variables were identified as risk factors for the development of ARF including age, male sex, diabetes mellitus, duration of bypass and aortic cross-clamping.9,10 In another study, the elderly and female patients had a higher risk of ARF.11

Among our patients, no relationship between the age and development of post-operation renal failure was noticed (p=0.805).

Effect of diabetes mellitus on post-operation ARF has been controversial. In some studies, diabetes mellitus is associated with the increase in risk of post-operation ARF, while others have failed to show this association.12 In our study, diabetic patients had a higher incidence of post-operation ARF.

In this study, duration of pump time was significantly related to post-operation ARF, but there was not any significant correlation between duration of clamp time and post-operation ARF.

Several studies1,6,8 reported the risk factors of post-operation ARF and predictive score charts were designed for prediction of post-operation complications such as Euro SCORE, Parsonnet score and Cleveland clinic score. These scoring systems might be beneficial for prediction of post-operation complications but their usefulness among our patients was unclear. There are controversies on risk factors that may promote post-operation ARF like diabetes mellitus,12 and gender of patients.9-11

Although several scoring algorithms are available for prediction of post-cardiac surgery complications, these can also be matched with our patients’ criteria enhancing their accuracy for our situation. Considering controversies, more studies still seem necessary to determine the risk factors of ARF after cardiac surgery.

 

 

Acknowledgment

 

Our Special thanks to Dr N. Shokrpour for the linguistic editing of the manuscript.

 

Conflict of interest: None declared.

References: (12)

  1. Chertow GM, Lazarus JM, Christiansen CL, Cook EF, Hammermeister KE, Grover F, Daley J. Preoperative renal risk stratification. Circulation 1997;95:878-84. [9054745]
  2. Thakar CV, Liangos O, Yared JP, Nelson D, Piedmonte MR, Hariachar S, Paganini EP. ARF after open-heart surgery: Influence of gender and race. Am J Kidney Dis 2003;41:742-51. [12666060] [doi:10.1016/S0272-6386(03)00021-0]
  3. Conlon PJ, Stafford-Smith M, White WD, Newman MF, King S, Winn MP, Landolfo K. Acute renal failure following cardiac surgery. Nephrol Dial Transplant 1999;14:1158-62. [10344355] [doi:10.1093/ndt/14.5.1158]
  4. Wesselink RM, de Boer A, Morshuis WJ, Leusink JA. Cardio-pulmonary-bypass time has important independent influence on mortality and morbidity. Eur J Cardiothorac Surg 1997;11:1141-5. [9237600] [doi:10.1016/S1010-7940(97)01217-7]
  5. Lombardi R, Ferreiro A, Servetto C. Renal function after cardiac surgery: adverse effect of furosemide. Ren Fail 2003;25:775-86. [14575286] [doi:10.1081/JDI-120024293]
  6. Thakar CV, Arrigain S, Worley S, Yared JP, Paganini EP. A clinical score to predict acute renal failure after cardiac surgery. J Am Soc Nephrol 2005;16:162-8. [15563569] [doi:10.1681/ASN.2004040331]
  7. O'Connor GT, Plume SK, Olmstead EM, Coffin LH, Morton JR, Maloney CT, Nowicki ER, Tryzelaar JF, Hernandez F, Adrian L, et al. A regional prospective study of in-hospital mortality associated with coronary artery bypass grafting. The Northern New England Cardiovascular Disease Study Group. JAMA 1991;266:803-9. [1907669]
  8. Mehta RH, Grab JD, O'Brien SM, Bridges CR, Gammie JS, Haan CK, Ferguson TB, Peterson ED; Society of Thoracic Surgeons National Cardiac Surgery Database Investigators. Bedside tool for predicting the risk of postoperative dialysis in patients undergoing cardiac surgery. Circulation 2006;114:2208-16. [17088458] [doi:10.1161/CIRCULATIONAHA.106.635573]
  9. Rosner MH, Okusa MD. Acute kidney injury associated with cardiac surgery. Clin J Am Soc Nephrol 2006;1:19-32. [17699187] [doi:10.2215/CJN.00240605]
  10. Kubal C, Srinivasan AK, Grayson AD, Fabri BM, Chalmers JA. Effect of risk-adjusted diabetes on mortality and morbidity after coronary artery bypass surgery. Ann Thorac Surg 2005;79:1570-6. [15854935] [doi:10.1016/j.athoracsur.2004.10.035]
  11. Doddakula K, Al-Sarraf N, Gately K, Hughes A, Tolan M, Young V, McGovern E. Predictors of acute renal failure requiring renal replacement therapy post cardiac surgery in patients with preoperatively normal renal function. Interact Cardiovasc Thorac Surg 2007;6:314-8. [17669854] [doi:10.1510/icvts.2006.148874]
  12. Grayson AD, Khater M, Jackson M, Fox MA. Valvular heart operation is an independent risk factor for acute renal failure. Ann Thorac Surg 2003;75:1829-35. [12822624] [doi:10.1016/S0003-4975(03)00166-8]