Does Aspartate Aminotransferase to Alanine Aminotransferase Ratio Predict Acute Kidney Injury After Cardiac Surgery?

BACKGROUND: Aspartate aminotransferase (AST) to alanine aminotransferase (ALT) ratio (AST/ALT) frequently is used in the diagnosis and prognosis of liver diseases, however it is also used in the diagnosis and prognosis of many other diseases, such as myocardial infarction, acute ischemic stroke, and peripheral artery disease. Acute kidney injury (AKI) is one of the most important complications after cardiac surgery and is one of the main causes of morbidity and mortality. The purpose of the study was to analyze the relationship between AST to ALT and AKI after isolated coronary artery bypass graft surgery (CABG). METHODS: We retrospectively reviewed the prospectively collected data of 253 adult patients, who underwent isolated CABG surgery with normal renal function (baseline serum creatinine value <1.4 mg/dL). Preoperative (T0) and postoperative day 1 and day 3 (T1 and T2) serum AST and ALT levels were analyzed, and AST/ALT was calculated. A preoperative AST/ALT of 1.22 was found to be the best cutoff point for predicting postoperative AKI. Kidney injury was interpreted, according to RIFLE classification. The effect of AST to ALT ratio on AKI after CABG was determined using logistic regression analysis, and the results were expressed as odds ratio (OR) with a 95% confidence interval (CI). A P value < .05 was considered statistically significant. RESULTS: Postoperative AKI occurred in 40 patients (15.8%). On logistic regression analysis, higher AST/ALT both preoperatively and postoperatively were associated with an increased incidence of postoperative AKI (T0: OR, 3.983; 95% CI, 1.940-8.180, P < .001, T1: OR, 2.760; 95% CI, 1.381-5.515, P = .004, T2: OR, 2.515; 95% CI, 1.195-5.294, P = .015). CONCLUSION: Preoperative and postoperative elevated AST to ALT ratio seems to be associated with an increased incidence of AKI after elective isolated CABG surgery.

Multidimensional Evaluation of Pulmonary Function and Exercise Capacity by BODE Index in Patients with On-Pump Coronary Artery Bypass Grafting.

Coronary artery bypass grafting (CABG) often causes physiological changes in patients. Although functional changes, such as lung function and exercise capacity changes, are observed in patients, there are no detailed studies examining this. The aim was to compare preoperative and postoperative pulmonary function and exercise capacity in patients undergoing on-pump CABG with a multidimensional index (BODE index). Demographic and surgical characteristics of patients were recorded. Pulmonary function test, six-minute walk test (6MWT), and modified Medical Research Council (mMRC) dyspnea score were assessed and BODE index were calculated in preoperative and at six months postoperatively. A total of 75 patients were included with a mean ± standard deviation age of 59.8±10.0 years. The male to female ratio was 57/18. There was a statistically significant decrease in the forced expiratory flow at 25-75% (FEF25-75%) value after CABG. Other pulmonary function test values were also lower in the postoperative period compared to the preoperative period, but these changes were not significant. The mean distance achieved in the 6MWT (p=0.02) and the mMRC dyspnea score (p=0.001) were significantly better postoperatively. The BODE index, which combines these parameters, had increased in the postoperative period. Age (OR 1.09; 95% CI: 1.008-1.181) and postoperative FEF25-75% (OR -0.96; 95% CI: 0.938-0.988) were the independent predictors of BODE score ≥3 in multivariate analysis. Despite the decrease in pulmonary function in patients undergoing CABG, there was an improvement in exercise capacity and dyspnea score.

Subclinical Hypothyroidism Increases the Requirement of Renal Replacement Therapy After Cardiac Surgery.

BACKGROUND: Subclinical or biochemically diagnosed hypothyroidism (SCH) is defined as an elevated serum thyroid-stimulating hormone (TSH) with normal free thyroxine (FT4) levels. Thyroid hormones play a major role in the normal function of the heart and vascular physiology. Atherosclerosis, increased systemic vascular resistance, and decreased arterial compliance are common pathophysiological changes that may occur in hypothyroidism. Acute kidney injury (AKI) is one of the devastating complications after cardiac surgery. Age, diabetes mellitus (DM), preexisting renal dysfunction, hypertension, impaired left ventricular function, and severe arteriosclerosis are the major risk factors for the development of AKI. The purpose of the current study was to analyze the influence of SCH on AKI and the requirement of renal replacement therapy (RRT) after isolated coronary artery bypass graft surgery (CABG). METHODS: We retrospectively reviewed the prospectively collected data of 336 adult patients who underwent isolated CABG surgery with normal renal function (baseline serum creatinine value <1.4 mg/dL) from January 2017 to January 2019. The patients were divided into two groups either having the diagnosis of SCH (Group I, N = 47) or not (Group II, N = 289). SCH was diagnosed based on preoperative serum TSH and FT4 levels. Kidney injury was interpreted, according to RIFLE classification. The effect of SCH on AKI and the need for RRT after CABG was determined using logistic regression analysis and the results were expressed as odds ratio (OR) with a 95% confidence interval (CI). A P value < .05 was considered statistically significant. RESULTS: Subclinical hypothyroidism was diagnosed in 14% of all patients. Postoperative AKI occurred in 15 patients (31.9%) in Group I, whereas there were 42 patients (14.5%) in Group II. On logistic regression analysis, the presence of SCH was shown to be associated with an increased incidence of postoperative AKI (OR, 0.363; 95% CI, 0.181-0.727; P = .004). RRT was used in 2.97% of patients (seven patients in Group I and three patients in Group II, P < .001). The 30-day mortality was 2.1%. CONCLUSION: The presence of SCH seems to be associated with an increased incidence of AKI and increased requirement for RRT after cardiac surgery.

Preoperative Vitamin D Level is Associated with Postoperative Delirium After Cardiac Surgery in Patients Over 65 Years of Age.

INTRODUCTION: Delirium after cardiac surgery is a devastating and important complication. Delirium is defined as "disturbance in attention (i.e., reduced ability to direct, focus, sustain, and shift attention) and awareness (reduced orientation to the environment)." In this study, we analyzed the association of preoperative vitamin D levels and postoperative delirium after cardiac surgery in patients over 65 years. MATERIALS AND METHODS: We retrospectively reviewed the data of 212 adult patients above 65 years of age who underwent isolated coronary artery bypass graft surgery from January 2016 to January 2018. The mean age for Group I was 69.7 ± 7.4 and Group II was 70.6 ± 4.8 years. There were 112 female patients in Group I and 46 female patients in Group II. The patient population was divided into 2 groups based on preoperative serum vitamin D (25-hydroxyvitamin D [25-OHD]) levels (normal range of 25-75nmol/L). Group I included patients with preoperative serum 25-OHD level<25nmol/L. Group II included patients with preoperative serum 25-OHD level ≥25nmol/L. RESULTS: The incidence of delirium in this study was 30.2%. In this study, 138 patients (65.1%) had preoperative serum 25-OHD levels <25 nmol/L, and 74 patients (34.9%) had preoperative serum 25-OHD levels ≥25 nmol/L. Preoperative serum 25-OHD levels were associated with postoperative delirium after coronary artery bypass graft surgery. Our retrospective study illustrated that a lower preoperative serum level of 25-OHD was associated with postoperative delirium. Our results showed that 65.1% of patients had preoperative serum 25-OHD levels <25 nmol/L, and this was associated with postoperative delirium. CONCLUSION: Vitamin D deficiency exacerbates delirium after coronary artery bypass surgery with cardiopulmonary bypass. Whether the effects of vitamin D deficiency during this event represent separate or interrelated activities with cardiopulmonary bypass is an important question to address and prospective randomized studies are necessary to confirm these results.

Effect of Iloprost, a Prostacyclin Analogue, on Myocardial Ischemia-Reperfusion Injury

Myocardial ischemia-reperfusion injury continues to be observed during open heart surgery. Various experimental models have been developed to overcome this injury and to increase postoperative prognosis. This study was conducted to assess the effect that iloprost, a prostacyclin analogue, can have on myocardial ischemia-reperfusion injury. We evaluated tissue damage by measuring the levels of malonyldialdehyde (MDA), glutathione, and nitric oxide (NO) in tissue and perfusates. In this study, 20 guinea pig hearts were prepared by using the modified Langendorff perfusion apparatus to form control (n = 10) and experimental study groups (n = 10). Following a preischemic period of perfusion and an ischemic period of 20 minutes, control hearts were perfused with Krebs­Henseleit solution. In the experimental group, iloprost (0.45 µg/kg per hour) was included in the perfusates for the last 10 minutes of the preischemic phase. Following cardiac stabilization, heart rate (pulse/min), contractility (mm), and aortic pressure (mmHg) values were recorded at the end of preischemia, postischemia, and reperfusion. Perfusate and tissue analyses for glutathione, MDA, and NO levels were made in each group at the end of experiments. Iloprost was found to have protective effects against myocardial ischemia by means of increased myocardial contractility, decreased tissue/perfusate glutathione levels and inhibited rise of tissue/perfusate MDA observed in the iloprost-treated experimental group. Future investigations on myocardial ischemia-reperfusion injury must evaluate iloprost-related mechanisms.

Preoperative Urinary pH is Associated with Acute Kidney Injury After Cardiac Surgery in Non-Diabetic Patients.

BACKGROUND: Acute kidney injury is a common complication of cardiac surgery that increases morbidity and mortality. The present study aims to analyze the association of preoperative urinary pH with acute kidney injury after isolated coronary artery bypass graft surgery (CABG). METHODS: We retrospectively reviewed the data of 270 adult non-diabetic patients who underwent isolated CABG surgery with normal renal function. The perioperative data of the patients included demographic data, laboratory findings, morbidity, and mortality. The patient population was divided into four groups: Group I, patients with preoperative urinary pH=5; Group II, patients with preoperative urinary pH=5.5; Group III, patients with preoperative urinary pH=6-6.5; and Group IV, patients with preoperative urinary pH ≥ 7.0. Kidney injury was interpreted according to the Kidney Disease: Improving Global Outcomes (KDIGO). RESULTS: There were 108 patients (40%) in Group I, 44 patients (16.3%) in Group II, 78 patients (28.9%) in Group III, and 40 patients (14.8%) in Group IV. Postoperative acute kidney injury (AKI) occurred in 39 patients (36.1%) in Group I, 4 patients (9.1%) in Group II, and 2 patients (2,5%) in Group III. None of the patients developed AKI in Group IV. Renal replacement therapy was required in 8 patients (2.3%) (6 patients from Group I; 2 patients from Group II; P = .016). Thirty-day mortality occurred in 5 patients (1.9%) (5 patients from Group I; none from other groups; P =  .017). All of the patients required renal replacement therapy. Logistic regression analysis revealing the presence of lower pH levels preoperatively was shown to be associated with increased incidence of postoperative AKI (OR: 0.193; 95% CI: 0.103-0.361; P < .001). CONCLUSION: Low preoperative urinary pH (≤5.5) results in severe acute kidney injury and increases the rate of morbidity and mortality after isolated CABG.

The Influence of Metabolic Syndrome on Acute Kidney Injury Occurrence after Coronary Artery Bypass Grafting.

BACKGROUND: Metabolic syndrome (MetS) is defined as a cluster of systemic abnormalities: hyperglycemia, dyslipidemia, abdominal obesity, and hypertension. Acute kidney injury (AKI) is one of the devastating complications after cardiac surgery. Age, DM, preexisting renal dysfunction, hypertension, impaired left ventricular function, and severe arteriosclerosis of the aorta are the major risk factors for the development of AKI. The purpose of the current study was to analyze the influence of MetS on AKI occurring after coronary artery bypass grafting (CABG). METHODS: We retrospectively reviewed the prospectively collected data of 500 adult patients who underwent isolated CABG surgery with normal renal function (baseline serum creatinine value <1.4 mg/dL) from January 2011 to January 2015. The patients were divided into two groups either having the diagnosis of MetS (Group I) or not (Group II). MetS was diagnosed based on International Diabetes Federation definition. Kidney injury was interpreted according to RIFLE classification. The effect of MetS on AKI after CABG was determined using logistic regression analysis and the results were expressed as odds ratio (OR) with a 95% confidence interval (CI). A P value <.05 was considered statistically significant. RESULTS: Metabolic syndrome was diagnosed in 16.4% of all patients. Postoperative AKI occurred in 26 patients (31.7%) in Group I whereas there were 53 patients (12.7%) in Group II. On logistic regression analysis, the presence of MetS was shown to be associated with increased incidence of postoperative AKI (OR, 3.197; 95% CI, 1.850-5.526; P = .000). CONCLUSION: The presence of MetS seems to be associated with increased incidence of AKI after cardiac surgery. MetS is a modifiable issue; if its components are well controlled its dreadful effects after cardiac surgery might be controlled as well.

Urine Output during Cardiopulmonary Bypass Predicts Acute Kidney Injury after Coronary Artery Bypass Grafting.

OBJECTIVE: This study evaluated the relationship between the amount of urinary output during cardiopulmonary bypass and acute kidney injury in the postoperative period of coronary artery bypass grafting. METHODS: Two hundred patients with normal preoperative serum creatinine levels, operated on with isolated CABG between 2012-2014 were investigated retrospectively. The RIFLE (Risk, injury, failure, loss of function, and end-stage renal disease) risk scores were calculated for each patient in the third postoperative day. Patients were distributed into two groups in relation to the presence of acute kidney injury or not and these two groups were compared. RESULTS: The urinary output (mL/kg/hour) during cardiopulmonary bypass in the acute kidney injury negative group was significantly higher than in the acute kidney injury positive group (P = .022). In case of a urinary output value 3.70 and lower to predict acute kidney injury positivity, sensitivity was detected as 71.43%. Results of the analysis for urinary output predict positivity of acute kidney injury. CONCLUSION: We suggest that urine output during cardiopulmonary bypass is a significant criteria that could predict acute kidney injury following coronary artery bypass grafting with cardiopulmonary bypass. Attempts to increase the urine output during cardiopulmonary bypass could help to maintain the renal functions during and after surgery.