Perfusion
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Comparative Study
Comparison of the effect of venovenous versus venoarterial extracorporeal membrane oxygenation on renal blood flow in newborn lambs.
Venovenous extracorporeal membrane oxygenation (VV ECMO) using double lumen catheters is an alternative to venoarterial (VA) ECMO and allows for total blood flow using the patient's cardiac output in comparison to partial blood flow provided during VA ECMO. ⋯ VV and VA ECMO at partial bypass flows had comparable effect on blood pressure, renal blood flow and PRA level in this short-term study. However, unclamping of the ECMO bridges did differentially affect blood pressure and renal blood flow between VV and VA groups. We speculate that this repeated acute change in long-run VA ECMO support may play a role in the persistent hypertension seen in some patients.
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Hemodilution and increase in capillary permeability occurring with cardiopulmonary bypass (CPB) impose a risk for tissue edema and blood transfusion that may result in an increased complication rate after coronary artery bypass grafting (CABG). Of the 1280 consecutive patients undergoing isolated on-pump CABG, total fluid balance at the end of the operation was less than or equal to 500 mL in 1155 (Group 1) and more than 500 mL in 125 (Group 2). During CPB, blood was added to the reservoir only when the hematocrit fell to 17% or less and crystalloid solution only when the pump flow index fell below 2.0 L/min/m2. Anesthetic, surgical, and postoperative management and diagnoses were the same in all patients, and a single surgical and anesthesia team performed all operations. No patient was excluded from the study. ⋯ Hypertension, diabetes, chronic obstructive pulmonary disease, New York Heart Association (NYHA) Class III-IV, use of angiotensin converting enzyme (ACE) inhibitors, chronic renal failure, and female gender were the significant preoperative risk factors for increased volume replacement during CPB. The groups were similar in body mass index, preoperative hematocrit values, total fluid balance in the intensive care unit (ICU), and total chest tube output. However, red blood cells' transfusion rate, readmission rate to the ICU and length of hospital stay were significantly higher in Group 2 patients. Multiple logistic regression revealed that age > 70 years (p < 0.001, Odds Ratio (OR): 2, 95% CI: 1.4-2.8), and total fluid balance > 500 mL at the end of the operation (p < 0.01, OR: 2.2, 95% CI: 1.5-3.2) were the predictors of increased length of stay. For transfusion of red blood cells, age > 70 years (p < 0.0001, OR: 2.3, 95% CI: 1.6-3.3), and total fluid balance > 500 mL at the end of the operation (p < 0.001, OR: 2, 95% CI: 1.3-2.9) were the only significant risk factors. This study suggests that intraoperative volume overload increases blood transfusion and length of hospital stay in patients undergoing CABG.
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The aim of this study was to monitor the metabolism and blood flow in the interstitium of the skeletal muscle during cardiac surgery with cardiopulmonary bypass (CPB) and in the early postoperative period by means of microdialysis and to compare metabolic changes during CPB at normothermia (NT) and hypothermia (HT). Surgical revascularization using CPB was performed in 50 patients, 25 patients (group HT) were operated using hypothermic CPB, 25 (group NT) using normothermic CPB. Interstitial microdialysis was performed by two CMA 60 probes (CMA Microdialysis AB, Solna, Sweden) inserted into the patient's deltoid muscle. ⋯ The results showed dynamic changes in the interstitial concentrations of glucose, urea, glycerol and lactate, which depend on the phase of the surgery in the CPB and early postoperative phase in the both groups of patients. Higher tissue perfusion of the skeletal muscle was noted in those patients operated on in normothermia. The dynamics of the concentration changes of these substances in the interstitium of the skeletal muscle has been proven to be caused by both the metabolic activity of the tissue and by the blood flow through the interstitium of the muscle.
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To investigate the time course of fluid extravasation during cardiopulmonary bypass (CPB), we measured the peripheral tissue thickness (TT) by A-mode ultrasound in 34 patients undergoing elective cardiac surgery. TT of the forehead was determined by a handheld A-mode ultrasound device and 10 MHz Transducer at nine defined intervals, from the night before surgery until the first postoperative day. Mean calculated loss of 1700 +/- 40 mL (SEM) water during the fasting period resulted in a significant reduction of TT by 0.28 +/- 0.03 mm. ⋯ At discharge from ICU, negative fluid regimen resulted in a balance of -127 +/- 146 mL whereas TT declined significantly to +0.16 +/- 0.09 mm compared to baseline. Dehydration due to fasting and the marked interstitial fluid extravasation during CPB could be detected by the changes of the peripheral TT. We conclude that parts of the fluid load during CPB are shifted from the intravascular compartment to the interstitial space in a time-dependent manner.
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Clinical Trial Controlled Clinical Trial
Selection of optimal quantity of hydroxyethyl starch in the cardiopulmonary bypass prime.
Ringer's solution prime reduces colloid osmotic pressure and causes edema during cardiopulmonary bypass, while hydroxyethyl starch (HES) can be used to attenuate this effect. Fifty patients were classified into five equal groups: Group I (preoperative patients) is the control group and the other four groups (II, III, IV, V) received different volume ratios of Ringer's solution to HES (1:0, 2:1, 1:2, 0:1, respectively). ⋯ The results showed a reduction in interstitial fluid (ISF) expansion, changes in blood rheologic properties with the increase in HES quantity and shorter ventilation and recovery times in Groups IV and V. We concluded that the optimal HES quantity in the prime is two thirds, which insures an 85% reduction of ISF relative to Group II, shorter ventilation and recovery times and avoidance of the hazards of high levels of HES.