[Evaluation of the renal function in cardiac surgery with CPB: role of the cystatin C and the calculated creatinine clearance]. / Evaluation de la fonction rénale périopératoire en chirurgie cardiaque: rôle de la cystatine C et de clairance de la créatinine calculée.

OBJECTIVES: The evaluation of the renal function in cardiac surgery is difficult. The gold standard remains the creatinine clearance in clinical practice. Cystatin C was recently proposed in order to evaluate the renal function. The aim of our study was to evaluate the cystatin C in cardiac surgery with CPB. PATIENTS AND METHODS: After informed consent and ethical committee agreement, 60 patients operated in cardiac surgery with CPB were prospectively included. Cystatin C,measured and calculated (Cockcroft and MDRD methods) creatinine were compared with the Student t-test and with the Bland and Altman method. p<0,05 was considered as a significant threshold. RESULTS: The reproducibility of the calculated creatinine clearance was better when the urinary collecting time was below 400 minutes. The estimation of the creatinine clearance by the Cockcroft and MDRD methods is better when the clearance is low. A significant correlation between the creatinine clearance and the cystatin C does exist, but the correlation coefficient was low. In case of acute renal dysfunction, the increase of the creatinine occurred earlier than the increase of the cystatin C. CONCLUSION: In cardiac surgery with CPB, the evaluation of the renal function was not improved by the cystatin C.

[Metabolic acidosis after cardiac surgery with cardiopulmonary bypass revisited with the use of the Stewart acid-base approach]. / Evaluation de la théorie de Stewart lors de l'acidose métabolique survenant après chirurgie cardiaque sous circulation extracorporelle.

INTRODUCTION: According to the Stewart approach of acid-base regulation, chloride from either volume replacement or cardiopulmonary bypass (CPB) priming solution may induce metabolic acidosis. The alternative hypothesis stands in volume dilution with solutions free of bicarbonate. OBJECTIVES: Evaluate the acid-base status of patients undergoing cardiac surgery with CPB priming containing chloride and bicarbonate. MATERIAL AND METHODS: Prospective study. METHODS: Twenty-eight patients were prospectively included. Priming of CPB contained 47.4 mmol/l of bicarbonate and 97.7 mmol/l of chloride. Arterial blood samples were taken at 3 timings: prior (T1) and after (T2) CPB, and on arrival in the ICU (T3). Following measurements were performed: Na(+), K(+), Cl(-), Mg(++), Ca(++), phosphates, albumin, lactate and arterial blood gases. RESULTS: After CPB respiratory acidosis was observed. There was a significant increase of chloride with a decrease in apparent strong ion difference (SIDa). At the same time bicarbonate and base excess (BE) remained constant. A significant but weak correlation between BE and SIDa existed (r(2) = 0.06, p=0.024). On the contrary, no correlation was found between variations of BE and SIDa. However, the correlation was stronger between values and variations of bicarbonate and BE (respectively r(2)=0.605, p<0.0001 and r(2)=0.495, p<0.0001). CONCLUSION: No metabolic acidosis occurred after cardiac surgery when CPB was primed with bicarbonate. Therefore, it appears that chloride administration is not the main mechanism being involved in the acid-base regulation. This reinforces the hypothesis that metabolic acidosis during CPB may mainly be due to dilution of bicarbonate.

Cardiac output measurements in off-pump coronary surgery: comparison between NICO and the Swan-Ganz catheter.

BACKGROUND: The aim of this prospective study was to compare continuous cardiac output measurements of the non-invasive cardiac output system (NICO) with the pulmonary artery catheter during off-pump coronary bypass surgery. METHODS: Twenty-two patients enrolled for off-pump coronary surgery received both a pulmonary artery catheter and a non-invasive cardiac output system for measurement of cardiac output. Data were compared by the Bland-Altman method to calculate the degree of agreement and to analyse if a significant difference existed between the two methods of cardiac output measurements. RESULTS: Perioperatively, the non-invasive cardiac output underestimated cardiac output, but postoperatively overestimated it. The limits of agreement were larger during surgery compared to the postoperative period (-3.1; +2.5 vs. -1.4; +2.2 L min(-1)). Perioperatively, cardiac output measured with the pulmonary artery catheter varied from 0.5 to 7.5 L min(-1) (mean 3.6 L min(-1)) and with the non-invasive cardiac output from 0.5 to 8.4 L min(-1) (mean 3.9 L min(-1)). Postoperatively, these were 2.5-7.7 L min(-1) (mean 4.5 L min(-1)) and 2.3-8.4 L min(-1) (mean 4.9 L min(-1)), respectively. CONCLUSION: During off-pump cardiac surgery, the non-invasive cardiac output reliably measures cardiac output and does it more rapidly than a pulmonary artery catheter and may be more useful in order to detect rapid haemodynamic changes.

Thermal efficiency and environmental performances of a biogas-diesel stationary engine.

Municipal and agricultural waste, and sludge from wastewater treatment represent a large source of pollution. Gaseous fuels can be produced from waste decomposition and then used to run internal combustion engines for power and heat generation. The present paper focuses on thermal efficiency and environmental performances of dual-fuel engines fuelled with biogas. Experiments have been carried out on a Lister-Petter single cylinder diesel engine, modified for dual-fuel operation. Natural gas was first used as the primary fuel. An empirical correlation was determined to predict the engine load for a given mass flow rate for the pilot fuel (diesel) and for the primary fuel (natural gas). That correlation has then been tested for three synthesized biogas compositions. Computations were performed and the error was estimated to be less than 10%. Additionally, NOx and CO2 contents were measured from exhaust gases. Based on exhausts gas temperature, the activation energy and the pre-exponential factor of an Arrhenius law were then proposed, resulting in a simpler mean to predict NOx.

[Coronary thrombosis on patient with the factor V Leiden mutation]. / Thrombose coronarienne sur facteur V Leiden.

We report a documented observation of coronary thrombosis occurring in a 25-year-old patient with no risk factor, presenting a hereditary thrombophilia (facteur V Leiden) diagnosed a few months earlier in a context of venous thrombosis. This patient had a spread out anterior myocardial infarction with cardiac arrest due to a ventricular fibrillation; although he was quickly rescued by the mobile intensive Care Unit, the patient died 48 hours later, after cerebral anoxia. The mutation called factor V Leiden is a widely spread hereditary family thrombophilia (5 to 6% of the population) and is characterized by a resistance to activated C protein provoking a hypercoagulable state. The unexpected arterial thrombosis, very rare in that case, can be extremely serious and raises the question of a preventive medication such as antiplatelet agent or low-molecular-weight heparin as soon as the genetic abnormally has been proved to be symptomatic.

[Coronary spasm during repeated anesthesia]. / Spasme coronarien lors d'anesthésies itératives.

Coronary arterial spasm observed during the course of two repeated anaesthesias in a patient having undergone aorto-femoral bypass grafting is reported by the authors. Such complications are accompanied by serious ventricular arrhythmias, though transient and healing without sequelae. Clinical and electrocardiographic characteristics of peroperative coronary arterial spasm are underlined. In patients prone to developing such spasm, peroperative alkalosis, hypothermia and parasympathetic stimuli should be avoided. Are emphasized the efficiency of preventive treatment with calcium antagonists and that of intravenous nitroglycerin in the treatment of peroperative coronary arterial spasm when it does occur.