Edmundas Širvinskas

Cardiopulmonary bypass management and acute renal failure: risk factors and prognosis:

The aim of the study was to investigate if acute renal failure (ARF) following cardiac surgery is influenced by CPB perfusion pressure and to determine risk factors of ARF. Our research consisted of two studies. In the first study, 179 adult patients with normal preoperative renal function who had been subjected to cardiac surgery on CPB were randomized into three groups. The mean perfusion pressure (PP) during CPB in Group 65 (68 patients) was 60–69.9 mmHg, in Group 55 (59 patients) – lower than 60 mmHg and in Group 75 (52 patients) – 70 mmHg and higher. We have analyzed postoperative variables: central venous pressure, the need for diuretics, urine output, fluid balance, acidosis, potassium level in blood serum, the need for hemotransfusions, nephrological, cardiovascular and respiratory complications, duration of artificial lung ventilation, duration of stay in ICU and in hospital, and mortality. In the second study, to identify the risk factors for the development of ARF following CPB, we retrospectively analysed data of all 179 patients, divided into two groups: patients who developed ARF after surgery (group with ARF, n = 19) and patients without ARF (group without ARF, n = 160). We found that urine output during surgery was statistically significantly lower in Group 55 than in Groups 65 and 75. The incidence of ARF in the early postoperative period did not differ among the groups: it developed in 6% of all patients in Group 65, 4% in Group 55 and 6% in Group 75. There were no differences in the rate of other complications (cardiovascular, respiratory, neurological disorders, bleeding, etc) among the groups. There were 19 cases of ARF (10.6%), but none of these patients needed dialysis. We found that age (70.0 ± 7.51 vs. 63.5 ± 10.54 [standard deviation, SD], P = 0.016), valve replacement and/or reconstruction surgery (57.9% vs. 27.2%, P = 0,011), combined valve and CABG surgery (15.8% vs. 1.4%, P = 0.004), duration of CPB (134.74 ± 62.02 vs. 100.59 ± 43.99 min., P = 0.003) and duration of aortic cross-clamp (75.11 ± 35.78 vs. 53.45 ± 24.19 min., P = 0.001) were the most important independent risk factors for ARF. Cardiopulmonary bypass perfusion pressure did not cause postoperative renal failure. The age of patient, valve surgery procedures, duration of cardiopulmonary bypass and duration of aorta cross-clamp are potential causative factors for acute renal failure after cardiac surgery.

Early post-cardiac surgery delirium risk factors:

The purpose of this study was to identify the post-cardiac surgery delirium risk factors and to evaluate clinical outcomes. Data on 90 patients with postoperative delirium after cardiac surgery on cardiopulmonary bypass (CPB) were analyzed retrospectively. The patients were divided into two groups by evaluating the severity of the delirium: light and moderate delirium group (n=74) and severe delirium group (n=16). We found that the rate of early post-cardiac surgery delirium was low (4.17%). We have determined that post-cardiac surgery delirium prolonged the length of stay in the Intensive Care Unit (ICU) by (8.4 (8.6)) and the hospital stay by (23.6 (13.0)) days. The patients had higher preoperative risk scores, their age was 71.5 (8.9) years, the body mass index was 28.8 (4.4) kg/m2, the majority were male (72.2%), and the left ventricular ejection fraction was 46.1(11.9) %. Statistical analysis by multivariable logistic regression has indicated that increasing the dose of fentanyl administered during surgery over 1.4 mg also increased the possibility of developing a severe delirium (OR=29.4, CI 4.1-210.3) and longer aortic clamping time could be independently associated with severe postoperative delirium (OR=8.0, CI 1.7-37.2). After surgery, new atrial fibrillation (AF) episodes amounted to 53.3% and, after distinguishing the delirium severity groups, AF developed in the patients belonging to the severe delirium groups statistically significantly more frequently, 81.8 vs 47.3, where p=0.01. Our data suggest that early post-cardiac surgery delirium is not a common complication, but it prolonged the length of stay at the ICU and in the hospital. The delirium risk factors, such as longer aortic clamping time, the dose of fentanyl and new atrial fibrillation episodes occurring after cardiac surgery, are associated statistically significantly with the development of severe post-cardiac surgery delirium.

Hypertonic hydroxyethyl starch solution for hypovolaemia correction following heart surgery

Background . The aim of the study was to evaluate the effect of hypertonic NaCl hydroxyethyl starch solution on haemodynamics and cardiovascular parameters in the early postoperative period in patients for correction of hypovolaemia after heart surgery. Methods. Eighty patients undergoing myocardial revascularisation at the Clinic of Cardiac Surgery of the Heart Centre (Kaunas University of Medicine) were randomly divided into two groups. The HyperHaes® group (n = 40) received 250 ml 7.2% NaCl/6% HES solution and the control Ringers acetate group (n = 40) received placebo (500ml Ringers acetate solution) for volume correction after the surgery. Results. After infusion of HyperHaes® solution, cardiac index increased from 2.69 (0.7) to 3.52 (0.8)l/min/m2, systemic vascular resistance index, pulmonary vascular resistance index and the gradient between central and peripheral temperature decreased, and oxygen transport parameters improved. Ringers group patients needed more intensive infusion therapy (4050.0 (1102.2) ml in the Ringers group, 3513.7(762.5) ml in the HyperHaes® group). During the first 24 hours postoperatively, diuresis was significantly higher in the HyperHaes® group (3640.0 (1122.9) ml and 2736.0 (900.7) ml), total fluid balance was lower in HyperHaes® group (1405.6 (1519.0) ml and 2718.3 (1508.0) ml, respectively). After the infusion of HyperHaes ® solution, no adverse events were noted. Conclusions. HyperHaes ® solution had a positive effect on haemodynamic parameters and microcirculation. Oxygen transport was more effective after HyperHaes® solution infusion. Higher diuresis, lower need for the infusion therapy for the first 24 hours and lower total fluid balance were determined in the HyperHaes® group. No adverse effects were observed after HyperHaes® solution infusion. Perfusion (2007) 22, 121—127.

The influence of mean arterial blood pressure during cardiopulmonary bypass on postoperative renal dysfunction in elderly patients

The aim of the study was to find out if there is an optimal mean arterial blood pressure (MABP) during cardiopulmonary bypass (CPB) for renal function in elderly patients during the early postoperative period. We analysed the data of 122 patients >70 years of age with normal preoperative renal function who had been subjected to coronary artery bypass grafting (CABG) procedures on CPB. Patients were divided into 3 groups, according to MABP during CPB: group MP (n=50) included patients whose MABP was maintained between 60–70 mmHg; group LP (n=36), the MABP was <60 mmHg; and group HP (n=36) where the MABP was >70 mmHg. The patients’ clinical data were evaluated during the first three postoperative days. The rate of renal impairment (urine output <50ml/h) in the early postoperative period after cardiac surgery did not differ among the groups. Oliguria developed in 3 patients (6%) of the MP group, in 2 patients (5.6%) in the LP group and in 6 patients (16.7%) in the HP group (χ2=3.6, df=2, p=0.161). Evaluation of MABP on renal excretion showed that there was no difference in urine output among the groups. Serum creatinine levels at the end of the first postoperative day in groups MP, LP and HP were 102.7±20.1, 116.4±58.6 and 113.2±39.8 µmol/L, respectively (F=0.5, df=2, p=0.640). There were no significant differences among the groups at the end of the second and the third day either. Volume balance at the end of surgery and during the early postoperative period was similar in all groups. The need for diuretics did not differ among the groups. The length of postoperative hospital stay was not significantly different among the groups. Our study did not reveal any relationship between a MABP of 48-80 and postoperative renal dysfunction in elderly patients after CABG surgery.

A case-control study of readmission to the intensive care unit after cardiac surgery

Background The aim of this study was to identify predictors of repeated admission to the intensive care unit (ICU) of patients who underwent cardiac surgery procedures. Material/Methods This retrospective study analyzed 169 patients who underwent isolated coronary artery bypass grafting (CABG) between January 2009 and December 2010. The case group contained 54 patients who were readmitted to the ICU during the same hospitalization and the control group comprised 115 randomly selected patients. Results Logistic regression analysis revealed that independent predictors for readmission to the ICU after CABG were: older age of patients (odds ratio [OR] 1.04; CI 1.004–1.08); body mass index (BMI) >30 kg/m2 (OR 2.55; CI 1.31–4.97); EuroSCORE II >3.9% (OR 3.56; CI 1.59–7.98); non-elective surgery (OR 2.85; CI 1.37–5.95); duration of operation >4 h (OR 3.44; CI 1.54–7.69); bypass time >103 min (OR 2.5; CI 1.37–4.57); mechanical ventilation >530 min (OR 3.98; CI 1.82–8.7); and postoperative central nervous system (CNS) disorders (OR 3.95; CI 1.44–10.85). The hospital mortality of patients who were readmitted to the ICU was significantly higher compared to the patients who did not require readmission (17% vs. 3.8%, p=0.025). Conclusions Identification of patients at risk of ICU readmission should focus on older patients, those who have higher BMI, who underwent non-elective surgery, whose operation time was more than 4 hours, and who have postoperative CNS disorders. Careful optimization of these high-risk patients and caution before discharging them from the ICU may help reduce the rate of ICU readmission, mortality, length of stay, and cost.

Influence of aspirin or heparin on platelet function and postoperative blood loss after coronary artery bypass surgery

The aim of the study was to assess the effect of aspirin or heparin pretreatment on platelet function and bleeding in the early postoperative period after coronary artery bypass grafting (CABG) surgery. Seventy-five male patients with coronary artery disease who underwent CABG with cardiopulmonary bypass (CPB) were studied. The patients were divided into three groups: Group 1 (n = 25) included patients receiving aspirin pretreatment, Group 2 (n = 22) received heparin pretreatment, and Group 3 (n = 28) included patients who received no antiplatelet or anticoagulant pretreatment. Twenty-four hours after surgery, all patients were administered aspirin therapy that was continued throughout their hospitalization period. We assessed the following preoperative blood coagulation indices: activated partial thromboplastin time (aPTT), international normalized ratio (INR), and fibrinogen. We compared platelet count and platelet aggregation induced by adenosinediphosphate (ADP) before surgery, 1 h after surgery, 20 h after surgery and on the seventh postoperative day. We assessed drained blood loss within 20 postoperative hours. Preoperative blood coagulation indices did not differ among the groups. Platelet count was also similar. One hour after surgery, platelet count significantly decreased in all groups (p <0.001), after 20 postoperative hours it did not undergo any marked changes, and on the seventh postoperative day, it significantly increased in all groups (p <0.001). Before surgery, the lowest index of ADP-induced platelet aggregation was found in Group 1 (p <0.05). One hour after surgery, platelet aggregation significantly decreased in all groups, most markedly in Group 3 (p <0.001), yet after 20 h, its restitution tendency and a significant increase in all groups was noted. On the seventh day, a further increase in the statistical mean platelet aggregation value was noted in Groups 2 and 3. Comparison of platelet aggregation after 20 postoperative hours and on the seventh day after surgery revealed a significantly higher than 10% increase of the index in 32% of patients in Group 1 (p <0.05), 27.3% of patients in Group 2 (p <0.05) and in 35.7% of patients in Group 3 (p <0.001). The lowest statistically significant value of postoperative blood loss was noted in Group 2 (p <0.01). Our study has shown that aspirin or heparin pretreatment had no impact on the dynamics of platelet function in the early postoperative period after CABG. The lowest postoperative blood loss was noted in patients pretreated with heparin.

Effects of sevoflurane vs. propofol on mitochondrial functional activity after ischemia-reperfusion injury and the influence on clinical parameters in patients undergoing CABG surgery with cardiopulmonary bypass.

The aim of the study was to evaluate the effects of sevoflurane and propofol on the activity of mitochondrial function related to ischemia-reperfusion injury, myocardial damage biomarkers release and clinical parameters in the postoperative period. Seventy-two patients scheduled for elective coronary artery bypass graft surgery with cardiopulmonary bypass were randomized into two groups: 36 patients received sevoflurane during anesthesia (Group S) and 36 patients received propofol (Group P). To investigate the functional activity of mitochondria, we used skinned fibers prepared from biopsies of right atrial tissue before cardioplegia and after the aorta cross-clamp removal (within 10-15 minutes after reperfusion). Patients’ clinical data (length of stay in ICU, hemodynamic parameters, duration of mechanical ventilation (MV) and the amount of lactate and troponin I in the blood serum) were evaluated postoperatively. The results showed that, before cardioplegia and after reperfusion, there was no significant difference in the mitochondrial routine and State 3 respiration rates between the groups. The effect of cytochrome c was higher in Group P. Troponin I concentration at the 12th hour after the surgery was 2.2 ± 0.8 ng/mL in Group S and 3.5 ± 1.1 ng/mL in Group P (p<0.001). There were no significant differences in the duration of mechanical ventilation, hemodynamic parameters and length of stay in the ICU between the groups. We conclude that sevoflurane slightly protects the mitochondrial outer membrane from ischemia-reperfusion injury and the loss of cytochrome c, yet has the similar effect on clinical parameters in the postoperative period when compared to propofol.

Influence of early re-infusion of autologous shed mediastinal blood on clinical outcome after cardiac surgery

Various strategies have been proposed to decrease allogeneic blood transfusion requirements after cardiac surgery. The aim of the study was to evaluate the efficacy of collected and re-infused autologous shed mediastinal blood on a patients postoperative course. Ninety patients who underwent heart surgery with cardiopulmonary bypass (CPB) were studied. The patients were divided into two groups: Group 1 (n = 41) received the centrifuged autologous shed mediastinal blood collected from the cardiotomy reservoir 4 hours after surgery; in Group 2 (n = 49) all shed mediastinal blood was discarded (control group). Haemoglobin (Hb), haematocrit (Hct), C-reactive protein values, and leucocyte count were compared before surgery, at 4 h and 20 h after surgery, and on the fifth postoperative day. We have measured serum procalcitonin (PCT) concentration at 4 h and 20 h after CPB. We assessed drained blood loss within 20 postoperative hours. Leucocyte count, Hb, Hct values, C-reactive protein, and procalcitonin concentration did not differ between the groups before and at 4 h after surgery. Hb, Hct level, and leucocyte count were similar at 20 hours and on the fifth day after surgery. At 20 hours after surgery, an increase of serum PCT concentration (>0.5—2 ng/mL) was more frequent in Group 2 (58.3% vs. 33.3%; p = 0.03). On the fifth postoperative day, C-reactive protein concentration was lower in Group 1 (71.74 ± 15.23; p < 0.01) compared to Group 2 (93.53 ± 20.3). Postoperative blood loss did not differ between the groups. Requirement for allogeneic blood transfusion was significantly lower in Group 1 (14.6% vs. 38.8%; p < 0.02). Patients in Group 1 developed less infective complications compared with Group 2 (2.4% and 16.3%, respectively; p < 0.05). The length of postoperative in-hospital stay was shorter in Group 1 compared with Group 2 (9.32 ± 2.55 and 16.45 ± 6.5, respectively; p < 0.05). We conclude that postoperative re-infusion of autologous red blood cells processed from shed mediastinal blood did not increase bleeding tendency and systemic inflammatory response and was effective in reducing the requirement for allogeneic transfusion, the rate of infective complications and the length of postoperative in-hospital stay. Perfusion (2007) 22, 345—352.

Effects of intraoperative external head cooling on short-term cognitive function in patients after coronary artery bypass graft surgery

The aim of study was to assess the effects of an intraoperative external head-cooling technique on cognitive dysfunction in the early postoperative period (at the 10th day) in patients after coronary artery bypass graft (CABG) surgery. Patients in Group H (n=25) were cooled with CPB and the intraoperative, external head-cooling technique, patients in Group C (n=25) were cooled only with cardiopulmonary bypass (CPB) to achieve mild hypothermia (33 – 34°C). Cognitive function was analyzed before the operation and after the surgery using the Mini Mental State Examination (MMSE), the Modified Visual Reproduction Test from the Wechsler Memory Scale, Trail Making (A/B), WAIS - Digit Span (WDS) and WAIS Digit Symbol Substitution Test (WDSST). The incidence of cognitive impairment at the 10th day after the surgery was 36% (n=9) in Group H and 64% (n=16) in Group C (p=0.048). The temperature during the aortic cross-clamp period was associated with a lower rate of cognitive dysfunction (p=0.05, r2=0.09). The intraoperative, external head-cooling technique during the aortic cross-clamp period has a neuroprotective effect and leads to less short-term cognitive function impairment after CABG surgery.

Effects of epidural anesthesia on intrathoracic blood volume and extravascular lung water during on-pump cardiac surgery

Background: The most important side effect of epidural anesthesia is hypotension with functional hypovolemia. Aggressive infusion therapy can reduce the hypotension effect. However, in conjunction with cardiopulmonary bypass, it can increase acute lung injury. We hypothesized that epidural anesthesia, by reducing cardiac sympathetic tonus, with subsequent better pulmonary flow, does not increase lung interstitial fluids. Methods: Sixty patients undergoing coronary artery bypass graft (CABG) surgery with cardiopulmonary bypass (CPB) were randomized to combined general anesthesia with epidural anesthesia / analgesia, (EA) group, and to general anesthesia with i/v opiate analgesia, (GA) group. Patients in the EA group received a high thoracic epidural, preoperatively. Intraoperatively, 0.25% bupivacaine 8 mL/h was infused and general anesthesia with sevoflurane was followed by bupivacaine infusion for 48 hours postoperatively. General anesthesia in the GA group was with sevoflurane and fentanyl 10 - 12 µg/kg and analgesia with pethidinum 0.1 - 0.4 mg/kg i.v. postoperatively. Global end-diastolic volume index (GEDI), intrathoracic blood volume index (ITBI) and extravascular lung water index (ELWI) were measured before anesthesia, before CPB and 15, 60, 180, 600 min. and 24 hr after CPB. Duration of mechanical lung ventilation was registered in both groups. Results: ITBI and GEDI were significantly higher in the EA group at all time points of measurement (ITBI 945.6±146.4 ml/m2 and 870.6±146.5 ml/m 2 vs. 1118±153.2 ml/m2 and 1020±174.9 ml/m 2; GEDI 720±96.19 ml/m2 and 775.0±159.5 ml/m 2 vs. 805.4±97.59 ml/m2 and 888±117.3 ml/m 2). GEDI was significantly lower in the GA group compared with baseline (801.9±132.4 ml/m2 vs. 695±169.2 mL/m2). ELWI was significantly higher in the GA group (7.233±1.35 ml/kg and 7.333±1.32 ml/kg vs. 8.533±1.45 ml/kg and 8.633±1.71 ml/kg), but without significant changes in the EA group. Duration of mechanical lung ventilation was shorter in the EA group (663.7±98.39 min. vs. 362.2±33.72 min.). Conclusions: Epidural anesthesia / analgesia does not increase interstitial lung fluids by increasing intrathoracic blood volume or the amount of infusion fluids in patients undergoing cardiac surgery under cardiopulmonary bypass. There is, also, a decreased duration of mechanical lung ventilation.