Comparative effects of hemodilutional anemia and transfusion during cardiopulmonary bypass on acute kidney injury: a prospective randomized study.

AIM: Acute kidney injury after cardiopulmonary bypass has been associated with dilutional anemia during surgery. We aimed both to explore if this relation is modulated by blood transfusion and to understand the postoperative contribution of protein oxidation. METHODS: In this randomized prospective study, after ethics committee approval and informed consent, 30 patients undergoing first-time elective coronary artery bypass grafting (CABG) with hematocrit between 21% and 25% at any time during extracorporeal circulation (ECC) were randomly and equally allocated into two groups. Group I consisted of patients who received red blood cells (RBC) during ECC, while in Group II, patients did not receive any RBCs. Besides routine hemodynamic and biochemical parameters, markers of renal injury such as neutrophil gelatinase-associated lipocalin (NGAL), creatinine clearance, and protein oxidation parameters (advanced oxidative protein products [AOPP], total thiol [T-SH]) were determined in both groups. RESULTS: (1) Both cardiovascular parameters (MAP, HR) and the hospitalization period of the transfused group were not significantly different compared to the non-transfused group (P > .05); (2) While urine NGAL level (P < .05) increased and GFR (P < .01) decreased in the transfused group compared to the preoperative period, there were no significant changes in respective parameters of the non-transfused group compared to preoperative period; (3) AOPP concentrations did not change compared to postoperative periods in both groups (P > .05). However, T-SH concentration showed a transient increased at postoperative hour 6 (P < .001 vs preoperative period) but normalized at postoperative hour 24 (P > .05 versus preoperative period). CONCLUSION: These findings suggest that a hematocrit value over 21% during ECC is safe for renal functions. RBC transfusion just to increase hematocrit may be deleterious.

Utility of cerebral oxymetry for assessing cerebral arteriolar carbon dioxide reactivity during cardiopulmonary bypass.

BACKGROUND: Our study evaluated changes in cerebral arterial oxygen saturation (rSO2) during cardiopulmonary bypass (CPB) that were caused by changes in arterial carbon dioxide tension (PaCO2). METHODS: A group of 126 patients undergoing routine, elective, first-time coronary artery bypass graft surgery (CABG) was entered into a prospective study using bilateral near-infrared spectroscopy (NIRS) before anesthetic induction (T1), after anesthetic induction (T2), and continuing at 5-minute intervals during moderate hypothermic (32°C) CPB. Pump flows were set at 2.5 L/min/m(2) and adjusted to maintain mean arterial pressure (MAP) within 10 mmHg of the MAP recorded at the initial fifth minute of CPB (T3). Thirty-two patients were excluded from data collection because MAP could not be stabilized within the target range of 60-90 mmHg. In the remaining 94 patients, after obtaining steady state flow, MAP, and oxygenation, a trial period of hypocarbia (mean PaCO2 of 30 mmHg) was induced by increasing oxygenator fresh gas flow rate (FGFR) to 2.5 L/min/m(2) (T4). A reciprocal period was then measured at reduced FGFR (0.75 L/min/m(2)) (T5). RESULTS: After 20 minutes of a higher (2.75 L/min/m(2)) (FGFR), mean PaCO2 decreased from a baseline of 38 ± 4 mmHg to 30 ± 2 mmHg. This was associated with a parallel decrease (-10 ± 9%) in mixed cerebral oxygen saturation without alteration of mean arterial oxygen tension (PaO2), lactate, MAP, CPB flow, or other parameters implying increased cerebral oxygen extraction. CONCLUSION: Parallel changes in PaCO2 and rSO2 occur during CPB when other variables remain constant, and are due to the effects of carbon dioxide on cerebral arterioles. Cerebral oxygen saturation measured by NIRS may be a useful indirect measure of PaCO2 when continuous blood gas analysis is not possible during open-heart surgery. Cerebral oximetry values may be useful measurements for setting an optimum gas flow rate through the oxygenator.

Is the Nexfin finger cuff method for cardiac output measurement reliableduring coronary artery bypass grafting? A prospective comparison with the echocardiography and FloTrac/Vigileo methods.

BACKGROUND/AIM: The aim of the current study was to assess the accuracy of cardiac output (CO) measurements obtained by the Nexfin finger cuff method as compared with the FloTrac/Vigileo and echocardiography methods in coronary artery bypass grafting (CABG) patients. MATERIALS AND METHODS: First-time elective CABG patients were prospectively enrolled in this study and divided into three groups according to CO measurement method. CO measurements were performed simultaneously by three different contributors and were collected by the fourth one 24 h postoperative in the intensive care unit (ICU). Data were statistically analyzed. RESULTS: Seventeen female and 13 male patients between 42 and 78 years of age (with a mean of 56 ± 4) were the subjects of this study. The mean CO measurements were 5.9 ± 1.4 L/min, 5.8 ± 1.1 L/min, and 6.0 ± 1.1 L/min for the Nexfin, FloTrac/Vigileo, and echocardiography methods, respectively (P > 0.05). The correlation values between Nexfin and FloTrac/Vigileo, Nexfin and echocardiography, and FloTrac/Vigileo and echocardiography were r = 0.445, r = 0.377, and r = 0.384, respectively (P < 0.05). CONCLUSION: Nexfin yielded results comparable to those obtained with FloTrac/Vigileo and echocardiography for the postoperative CO assessment of CABG patients. Nexfin may be used in uncomplicated, hemodynamically stable patients in ICU as a reliable and totally noninvasive method of CO measurement.

Cesarean under general or epidural anesthesia: does it differ in terms of regional cerebral oxygenation?

OBJECTIVE: It is aimed to evaluate whether there is a difference in regional cerebral saturation of newborns measured by near infrared spectroscopy born either by general anesthesia or combined spinal epidural anesthesia during elective cesarean deliveries. METHODS: After approval from the ethics committee of our hospital, and informed consents of the parturients were taken, 68 patients were included in the study. The regional cerebral oxygen saturations (RcSO2) of newborns were measured by near infrared spectroscopy (NIRS) measurements at 1st, 5th min after birth. In group I (n=32), general anesthesia was performed for the cesarean operation and in group II (n=36), combined spinal epidural anesthesia (CSEA) was the anesthetic management. The age of the mother, gestation, the problems related to the pregnancy, heart rate, blood pressure, oxygen saturation (SpO2) of the mother had been recorded. The measurements of the newborn were; SpO2 of right hand, RcSO2 measured by NIRS, the delivery time (from incision to the cessation of circulation in the placental cord), Apgar score. Data were analyzed using GraphPad Prism 5.0 (GraphPad Software, La Jolla, California) and presented as mean +/- SD. Results obtained in different groups were compared using upaired t-test. Differences were statistically significant at p < 0.05. RESULTS: There were no significant differences between the groups related to the mother's age, gestation week and baseline blood pressure. Both the systolic and diastolic blood pressures measured at 1st and 5th min after induction or start of the spinal block were significantly lower in the mothers who had undergone combined spinal epidural anesthesia. The heart rates of the mothers who had been under CSEA were significantly higher than the general anesthesia group. The Apgar at the 1st min were observed significantly higher in Group II. Oxygen saturation of the newborns were significantly higher in Group II. Regional cerebral oxygenation measured by NIRS were significantly higher in CSEA group. CONCLUSION: Combined spinal epidural anesthesia, besides other known advantages, had been shown to be superior to general anesthesia as a means of regional cerebral oxygenation of the newborns.