Denis Safran

High-volume, zero-balanced hemofiltration to reduce delayed inflammatory response to cardiopulmonary bypass in children

Background In previous studies, researchers suggested a beneficial role of hemofiltration performed during cardiopulmonary bypass in children. This study was performed to assess both clinical effects and inflammatory mediator removal by high-volume, zero-fluid balance ultrafiltration during rewarming (Z-BUF). Methods Twenty children undergoing cardiac surgery were assigned randomly to Z-BUF or a control group. Plasma C3a, interleukin (IL)-1, IL-6, IL-8, IL-10, tumor necrosis factor, myeloperoxidase, and leukocyte count were measured before (T1) and after (T2) hemofiltration and 24 h later (T3). The intensive care unit staff was blinded to the patients group. Postoperative alveolar-arterial oxygen gradient, time to extubation, body temperature, and postoperative blood loss were monitored. Results Ultrafiltration rate was 4,972 (3,183-6,218) mL/m2 (median [minimum-maximum]) in the Z-BUF group, where significant reductions were observed in postoperative blood loss, time to extubation (10.8 [9-18] vs. 28.2 [15-58] h) and postoperative alveolar-arterial oxygen gradient (320 [180-418] vs. 551 [485-611] mmHg at T3). In the Z-BUF group, significant removal of tumor necrosis factor, IL-10, myeloperoxidase, and C3a were observed at T2. Interleukin 1, IL-6, IL-8, and myeloperoxidase were decreased at T3, suggesting earlier removal of factor(s) that may trigger their release. Conclusions These results suggest that hemofiltration exerts some beneficial clinical effects that are not due to water removal. The role of the early removal of factors triggering the inflammatory response, rather than a direct removal of cytokines, deserves further investigation.

Hemofiltration during cardiopulmonary bypass in pediatric cardiac surgery. Effects on hemostasis, cytokines, and complement components.

BackgroundThis prospective study was intended to determine in a homogeneous population of children whether hemofiltration, performed during cardiopulmonary bypass rewarming, is able to Improve hemodynamics and biologic hemostasis variables, to reduce postoperative blood loss, time to extubation, and plasma cytokines, and complement fragments. MethodsThirty-two children undergoing surgical correction of tetralogy of Fallot were randomly assigned to a hemofiltration or control group. Hemofiltration was performed with a polysulphone hemofilter during rewarming of cardiopulmonary bypass. Plasma clotting factors, D-dimers, antithrom-bin-III, complement fragments C3a and C5a, interleukin-lβ, interleukln-6, interleukin-8, and tumor necrosis factor-a were measured before and after hemofiltration. Systemic mean arterial pressure, left atrial pressure, time to extubation, and postoperative blood loss were monitored. ResultsIn the hemofiltration group, significant reductions in 24-h blood loss (250 (176–356) vs. 319 (182–500) ml/m2, median (minimum-maximum)), time to extubation (15 (9–22) vs. 19 (11–24) h), plasma concentrations of C3a, C5a, interleukin-6, and tumor necrosis factor-α were observed compared to control. Arterial oxygen tension on admission to the intensive care unit was significantly greater in the hemofiltration group (136 ± 20 vs. 103 ± 25 mmHg, mean ± SD). Significant increases in mean arterial pressure, clotting factors, and antithrombin-III were noted for the hemofiltration group. No intergroup difference was observed in left atrial pressure, platelets count, D-dimers, lnterleukin-8, and duration of stay in the Intensive care unit. ConclusionsHemofiltration during cardiopulmonary bypass in children Improves hemodynamics and early postoperative oxygenatlon and reduces postoperative blood loss and duration of mechanical ventilation. Hemofiltration is able to remove some major mediators of the inflammatory response.

Inhaled nitric oxide as a therapy for pulmonary hypertension after operations for congenital heart defects

Seventeen infants were treated with inhaled nitric oxide for critical pulmonary artery hypertension after operations for congenital heart defects. In all 17 patients conventional medical therapy consisting of hyperventilation, deep sedation/analgesia, and correction of metabolic acidosis had failed. All children were monitored with a transthoracic pulmonary artery catheter inserted at operation. Pulmonary artery hypertension was defined as an acute rise in pulmonary pressure associated with a decrease in oxygen arterial or venous saturation. After failure of conventional medical therapy, 20 ppm of inhaled nitric oxide was administered to the patient. In all patients the pulmonary pressures decreased (mean pulmonary arterial pressure decreased by -34% +/- 21%) without significant change in systemic arterial pressure, whereas the oxygen arterial saturation and oxygen venous saturation increased by 9.7% +/- 12% and 37% +/- 28%, respectively. Fifteen children were discharged from the intensive care unit at 10 +/- 6 days (range 3 to 26 days) and two died. This study demonstrates that inhaled nitric oxide exerts a selective pulmonary vasodilation without decreasing systemic arterial pressure in children with congenital heart disease. The increased values of mixed venous oxygen saturation and urinary output suggest that this selective lowering of pulmonary vascular resistance improved the overall hemodynamics. The potential toxic effects of nitric oxide and nitrogen dioxide necessitate careful consideration of the risks and benefits of inhaled nitric oxide therapy.

Assessment of coagulation factor activation during cardiopulmonary bypass with a new monoclonal antibody

Antithrombin-III (AT) is a key inhibitor of blood coagulation that neutralizes activated serine esterases by forming covalent modified complexes (ATm). A new monoclonal antibody directed against short-lived AT-activated serine protease complexes provides a means of measuring subclinical coagulation activity during cardiopulmonary bypass (CPB). Twelve patients undergoing CPB for coronary artery bypass grafting were studied and AT, ATm, D-dimers (DD), and several other coagulation and fibrinolytic markers were measured during the surgical procedure. There were decreases in AT, factors V, II, X, IX, protein S (total and free), C4b-binding protein, thrombomodulin, and platelets counts, whereas heparin, ACT, thrombospondin, plasminogen activator inhibitor (PAI-1), and tissue plasminogen activator (tPA) increased. ATm and the percentage of ATm available (ATm/AT) showed a peak during CPB. These results demonstrate that during CPB, the use of heparin produces an equilibrium involving increased coagulation activation and consumption in association with increased fibrinolysis. The equilibrated consumption of both coagulation and fibrinolytic factors leads to low levels of all factors after cardiac surgery. The ATm assay allows assessment of the differential effects of CPB and surgical trauma on coagulation activation. It is speculated that ATm levels may be useful in monitoring the consumption of coagulation factors.

Incidence, risk factors and prediction of post-operative acute kidney injury following cardiac surgery for active infective endocarditis: an observational study

IntroductionCardiac surgery is frequently needed in patients with infective endocarditis (IE). Acute kidney injury (AKI) often complicates IE and is associated with poor outcomes. The purpose of the study was to determine the risk factors for post-operative AKI in patients operated on for IE.MethodsA retrospective, non-interventional study of prospectively collected data (2000–2010) included patients with IE and cardiac surgery with cardio-pulmonary bypass. The primary outcome was post-operative AKI, defined as the development of AKI or progression of AKI based on the acute kidney injury network (AKIN) definition. We used ensemble machine learning (“Super Learning”) to develop a predictor of AKI based on potential risk factors, and evaluated its performance using V-fold cross validation. We identified clinically important predictors among a set of risk factors using Targeted Maximum Likelihood Estimation.Results202 patients were included, of which 120 (59%) experienced a post-operative AKI. 65 (32.2%) patients presented an AKI before surgery while 91 (45%) presented a progression of AKI in the post-operative period. 20 patients (9.9%) required a renal replacement therapy during the post-operative ICU stay and 30 (14.8%) died during their hospital stay. The following variables were found to be significantly associated with renal function impairment, after adjustment for other risk factors: multiple surgery (OR: 4.16, 95% CI: 2.98-5.80, p<0.001), pre-operative anemia (OR: 1.89, 95% CI: 1.34-2.66, p<0.001), transfusion requirement during surgery (OR: 2.38, 95% CI: 1.55-3.63, p<0.001), and the use of vancomycin (OR: 2.63, 95% CI: 2.07-3.34, p<0.001), aminoglycosides (OR: 1.44, 95% CI: 1.13-1.83, p=0.004) or contrast iodine (OR: 1.70, 95% CI: 1.37-2.12, p<0.001). Post-operative but not pre-operative AKI was associated with hospital mortality.ConclusionsPost-operative AKI following cardiopulmonary bypass for IE results from additive hits to the kidney. We identified several potentially modifiable risk factors such as treatment with vancomycin or aminoglycosides or pre-operative anemia.

Continuous Intercostal Blockade With Lidocaine After Thoracic Surgery

The efficacy and the side effects of a continuous infusion of lidocaine in the fifth intercostal space for the management of postoperative pain after lateral thoracotomy were evaluated in 20 adults. An indwelling catheter was inserted in the appropriate intercostal space before thoracotomy closure. After recovery from general anesthesia, a loading dose of 3 mg/kg of 1.5% lidocaine with epinephrine 1:160,000 was injected through the catheter, followed by a continuous infusion of 1% lidocaine without epinephrine at a rate of 1 mg.kg−1 for 54 h. In seven patients pharmacokinetic data were obtained. Pain, assessed by visual continuous analog scale, decreased from a median score of 8 (range, 7--10) to a score of 5 (range, 2--7) 20 min after the loading dose of lidocaine and continued to decrease until the end of the study (P = 0.0001). Complete cutaneous analgesia, assessed by pinprick test, was seen in a median of three thoracic spinal segments (range, 0--6) with partial cutaneous analgesia in seven segments (range, 6--9) 40 min after the loading dose, and levels that remained unchanged for 54 h (P = 0.0001). Peak lidocaine serum concentrations, 1.9 ± 0.7 ±g/mL, were present 9 ± 3 min after injection of the loading dose. Serum concentrations of lidocaine under steady state conditions averaged 4.8 ± 0.9 μg/mL (range, 3.5--5.8 μg/mL). This level under steady state conditions, though below the toxic level, suggests that additional bolus injection of lidocaine during the course of infusion might result in potentially toxic serum levels of lidocaine. Our data show that the intercostal infusion of lidocaine in a single intercostal segment after thoracotomy provides prompt, prolonged, and effective analgesia, without side effects and with a pharmacokinetic profile indicating that serum levels remain below toxic threshold values.

Effects of Laparoscopic Pneumoperitoneum and Changes in Position on Arterial Pulse Pressure Wave-Form: Comparison Between Morbidly Obese and Normal-Weight Patients

Background: Laparoscopic adjustable gastric banding (LAGB) is commonly indicated in morbidly obese patients. There is controversy regarding the hemodynamic effects of pneumoperitoneum (PNP) in obese patients. PNP and changes in body posture have complex effects on venous return that may be detected by respiratory changes in the arterial pressure waveform. The aim of this study was to compare pneumoperitoneum-induced and reverse Trendelenburg (RT) changes in arterial pulse pressure in obese and normal-weight patients. Methods: 15 morbidly obese patients undergoing LAGB were compared to 15 normal-weight patients undergoing laparoscopic surgery. Arterial pressure was non-invasively recorded using an arterial tonometer. Respiratory changes in pulse pressure (ΔPp) were recorded in the supine position without and with PNP, and in RT position with pneumoperitoneum. Results: PNP increased ΔPp values in normal weight (P<0.001), but not in obese patients. RT position increased ΔPp values in obese patients, but did not cause additional changes in normal-weight patients. Conclusions: Unlike normal-weight patients, PNP in the supine position has minimal effect on the arterial pulse-pressure wave-form in obese patients. This observation may reflect physiological differences in total blood volume and loading conditions of the heart between morbidly obese and normal-weight patients, which affect venous return during PNP. Differences in abdominal vascular zone conditions between obese and normal weight-patients may explain these results.

Low social support is associated with an increased risk of postoperative delirium.

STUDY OBJECTIVE To examine the predictive value of social support in postoperative delirium. DESIGN Prospective observational study. SETTING Postoperative recovery room and orthopedic surgery department. PATIENTS 106 consecutive patients undergoing a planned orthopedic surgery with general anesthesia. MEASUREMENTS All patients completed questionnaires to assess depressive mood (the Beck Depression Inventory) and social support (Sarasons Social Support Questionnaire) during the preanesthesia visit. Postoperative delirium symptoms were assessed daily using the Memorial Delirium Assessment Scale. Demographic, clinical, and biological data, including anesthesia procedure, were recorded. MAIN RESULTS Controlling for various potential confounders through multivariate binary logistic regression, postoperative delirium was independently predicted by satisfaction with social support, but neither by depressive mood nor the number of supportive persons. Other significant predictors were the preoperative use of benzodiazepines, age, and type of surgery. CONCLUSION Patients who report low satisfaction with social support may present with a particular vulnerability to postoperative delirium, even after controlling for physical confounding variables and depressive mood.

Circuits anesthésiques accessoires: vérification avant utilisation

Accessory or ancillary anaesthesia breathing systems can be defined as all those connected to the fresh gas outlet of the anaesthetic apparatus and used instead of the circle system associated with the ventilator, which is the main circuit. They include: the Mapleson systems, the systems with a nonrebreathing valve and the disposable systems with a carbon dioxide absorber. They can be a cause of major accidents when not checked before and monitored during use. This technical note describes techniques of preanaesthetic checking and monitoring during anaesthesia.

Surveillance continue de la SV˙o2 au cours de l'anesthésie pour chirurgie pulmonaire

The multiplicity of potential causes of variations in mixed venous oxygen saturation (Sv2) during one lung ventilation (OLV), including a constant ventilation/perfusion mismatch, explains that it has been suggested as a routine monitoring procedure. To assess its usefulness, 12 adults undergoing OLV were monitored during surgery with an Oximetrix® pulmonary catheter, placed on the side opposite to the surgical field under fluoroscopic control. Seventy two complete sets of haemodynamic measurements were obtained at 6 different times during surgery. We studied the ability of changes in Sv2 to predict changes in arterial oxygen saturation (Sao2), cardiac output (CO), and venous admixture (VA) by calculating sensitivities (Se), specificities (Sp) and predictive values with regard to these variables. There were no complications due to the protocol. However left-sided catheter placement failed in four cases. Correlation between optical and measured Sv2 was very strong (r=0.94; p<0.001). Sv2, oxygen consumption (V˙o2) and the rate of oxygen extraction remained constant throughout the procedure, even when CO, mean arterial pressure, VA, Sao2 and Pao2 varied. Clamping the pulmonary artery returned VA, Sao2 and Pao2 values to those found before OLV, but produced a significant decrease in CO. Sv2 had low Se and Sp for changes in other variables (CO: 76±7, 48±9; Pao2: 79±6, 59±9; VA: 54±7, 48±7 respectively). In this type of surgery, alterations in variables related to oxygen are probably balanced by haemodynamic changes. In fact, according to Ficks formula, Sv2 is almost completely determined by Sao2 and CO, when V˙o2 and haemoglobin remain stable. However, a decrease in Sv2 should alert the clinician to a potential change in haemodynamic indices or to a problem in some component in the oxygen delivery system. Sv2 values do not add to or correlate well with other data, but facilitate their continuous monitoring.