Pierre-Guy Chassot

Preconditioning by Sevoflurane Decreases Biochemical Markers for Myocardial and Renal Dysfunction in Coronary Artery Bypass Graft Surgery: A Double-blinded, Placebo-controlled, Multicenter Study

Background Preconditioning by volatile anesthetics is a promising therapeutic strategy to render myocardial tissue resistant to perioperative ischemia. It was hypothesized that sevoflurane preconditioning would decrease postoperative release of brain natriuretic peptide, a biochemical marker for myocardial dysfunction. In addition, several variables associated with the protective effects of preconditioning were evaluated. Methods Seventy-two patients scheduled for coronary artery bypass graft surgery under cardioplegic arrest were randomly assigned to preconditioning during the first 10 min of complete cardiopulmonary bypass with either placebo (oxygen–air mixture only) or sevoflurane 4 vol% (2 minimum alveolar concentration). No other volatile anesthetics were administered at any time during the study. Treatment was strictly blinded to anesthesiologists, perfusionists, and surgeons. Biochemical markers of myocardial dysfunction and injury (brain natriuretic peptide, creatine kinase–MB activity, and cardiac troponin T), and renal dysfunction (cystatin C) were determined. Results of Holter electrocardiography were recorded perioperatively. Translocation of protein kinase C was assessed by immunohistochemical analysis of atrial samples. Results Sevoflurane preconditioning significantly decreased postoperative release of brain natriuretic peptide, a sensitive biochemical marker of myocardial contractile dysfunction. Pronounced protein kinase C &dgr; and &egr; translocation was observed in sevoflurane-preconditioned myocardium. In addition, postoperative plasma cystatin C concentrations increased significantly less in sevoflurane-preconditioned patients. No differences between groups were found for perioperative ST-segment changes, arrhythmias, or creatine kinase–MB and cardiac troponin T release. Conclusions Sevoflurane preconditioning preserves myocardial and renal function as assessed by biochemical markers in patients undergoing coronary artery bypass graft surgery under cardioplegic arrest. This study demonstrated for the first time translocation of protein kinase C isoforms &dgr; and &egr; in human myocardium in response to sevoflurane.

Adaptive support ventilation for fast tracheal extubation after cardiac surgery: a randomized controlled study.

Background Adaptive support ventilation (ASV) is a microprocessor-controlled mode of mechanical ventilation that maintains a predefined minute ventilation with an optimal breathing pattern (tidal volume and rate) by automatically adapting inspiratory pressure and ventilator rate to changes in the patient’s condition. The aim of the current study was to test the hypothesis that a protocol of respiratory weaning based on ASV could reduce the duration of tracheal intubation after uncomplicated cardiac surgery (“fast-track” surgery). Methods A group of patients being given ASV (group ASV) was compared with a control group (group control) in a randomized controlled study. After coronary artery bypass grafting during general anesthesia with midazolam and fentanyl, patients were randomly assigned to group ASV or group control. Both protocols were divided into three predefined phases, and weaning progressed according to arterial blood gas and clinical criteria. In phase 1, ASV mode was set at 100% of the theoretical value of volume/minute in group ASV, and synchronized intermittent mandatory ventilation mode was used in group control. When spontaneous breathing occurred, ASV setting was reduced by 50% of minute ventilation (phase 2) and again by 50% (phase 3), and the trachea was extubated. In group control, the ventilator was switched to 10 cm H2O inspiratory pressure support (phase 2), then to 5 cm H2O (phase 3) until extubation. Results Forty-nine patients were enrolled. Sixteen patients completed the ASV protocol, and 20 the standard protocol; 7 patients were excluded in group ASV and 6 in group control according to explicit, predefined criteria. There were no differences between groups in perioperative characteristics or in the doses of sedation. The primary outcome of the study, that is, the duration of tracheal intubation, was shorter in group ASV than in group control (median [quartiles]: 3.2 [2.5–4.6]vs. 4.1 [3.1–8.6] h;P < 0.02). Fewer arterial blood analyses were performed in group ASV (median number [quartiles]: 3 [3–4]vs. 4 [3–6]), suggesting that fewer changes in the settings of the ventilator were required in this group. Conclusions A respiratory weaning protocol based on ASV is practicable; it may accelerate tracheal extubation and simplify ventilatory management in fast-track patients after cardiac surgery. The evaluation of potential advantages of the use of such technology on patient outcome and resource utilization deserves further studies.

Urological surgery and antiplatelet drugs after cardiac and cerebrovascular accidents.

PURPOSE The perioperative treatment of patients on dual antiplatelet therapy after myocardial infarction, cerebrovascular event or coronary stent implantation represents an increasingly frequent issue for urologists and anesthesiologists. We assess the current scientific evidence and propose strategies concerning treatment of these patients. MATERIALS AND METHODS A MEDLINE and PubMed search was conducted for articles related to antiplatelet therapy after myocardial infarction, coronary stents and cerebrovascular events, as well as the use of aspirin and/or clopidogrel in the context of surgery. RESULTS Early discontinuation of antiplatelet therapy for secondary prevention is associated with a high risk of coronary thrombosis, which is further increased by the hypercoagulable state induced by surgery. Aspirin has recently been recommended as a lifelong therapy. Clopidogrel is mandatory for 6 weeks after myocardial infarction and bare metal stents, and for 12 months after drug-eluting stents. Surgery must be postponed beyond these waiting periods or performed with patients receiving dual antiplatelet therapy because withdrawal therapy increases 5 to 10 times the risk of postoperative myocardial infarction, stent thrombosis or death. The shorter the waiting period between revascularization and surgery the greater the risk of adverse cardiac events. The risk of surgical hemorrhage is increased approximately 20% by aspirin and 50% by clopidogrel. CONCLUSIONS The risk of coronary thrombosis when antiplatelet agents are withdrawn before surgery is generally higher than the risk of surgical hemorrhage when antiplatelet agents are maintained. However, this issue has not yet been sufficiently evaluated in urological patients and in many instances during urological surgery the risk of bleeding can be dangerous. A thorough dialogue among surgeon, cardiologist and anesthesiologist is essential to determine all risk factors and define the best possible strategy for each patient.

Intrathecal sufentanil-morphine shortens the duration of intubation and improves analgesia in fast-track cardiac surgery.

PurposeTo compare the effect of combined intrathecal morphine and sufentanil with low-doseiv sufentanil during propofol anesthesia for fast-track cardiac surgery.MethodsTwenty-four consecutive patients with normal cardiopulmonary function who were scheduled for elective cardiac surgery were randomized to receive either a continuousiv infusion of sufentanil 0.9 to 1.8μg· kg−1· min−1 (13 patients), or a single lumbar intrathecal dose of sufentanil 50 μg and morphine 500 μg (11 patients). We prospectively studied perioperative analgesia, time to extubation and early postoperative maximal inspiratory capacity in the two groups. In the intensive care unit, the medical and nursing staff were blinded to the analgesic technique.ResultsIntrathecal sufentanil morphine allowed a shorter duration of intubation (104 ± 56.5 minvs 213 ± 104 min;P = 0.01), reduced the need for postoperative analgesia with nicomorphine (equipotentto morphine) (0.7 ± 0.4 mg· hr−1vs 1.2 ± 0.4 mg· hr−1;P = 0.008) and improved postoperative maximal inspiratory capacity (53.4 ± 16.1vs 38.4 ± 12.5% of the norm;P = 0.05). Conclusion: In low-risk patients undergoing coronary artery bypass graft or valve surgery, combined intrathecal sufentanil and morphine with a target-controlled infusion of propofol satisfies the goals of fast-track cardiac surgery.RésuméButComparaison de l’effet de l’administration intrathécale combinée de morphine et de sufentanil avec l’administration iv de sufentanil lors d’une anesthésie à base de propofol pour la chirurgie cardiaque “fast-track”.MéthodeVingt-quatre patients consécutifs ayant une fonction cardiopulmonaire dans les limites de la normale ont été admis en vue d’une intervention cardiaque programmée et ont été randomisés en deux groupes distincts: l’un recevant une perfusion iv continue de 0,9 à 1,8 μg· kg−1· min−1 de sufentanil (13 patients) et l’autre une dose unique intrathécale de 50 μg de sufentanil et 500 μg de morphine (11 patients). Nous avons étudié prospectivement l’analgésie périopératoire, le délai d’extubation et la capacité inspiratoire maximale postopératoire dans ces deux groupes de patients. Aux soins intensifs, le personnel soignant médical et paramédical ignoraient la technique analgésique utilisée.RésultatsL’administration intrathécale de sufentanil et de morphine a permis une extubation plus rapide (104 ± 56,5 min vs 213 ± 104 min; P = 0,01), une réduction des besoins analgésiques en nicomorphine (puissance équivalente à la morphine) (0,7 ± 0,4 mg· h−1 vs 1,2 ± 0,4 mg· h−1; P = 0,008) et une amélioration de la capacité inspiratoire maximale postopératoire (53,4 ± 16,1 vs 38,4 ± 12,5 % de la norme; P = 0,05).ConclusionChez les patients à bas risque opératoire programmés pour des pontages aortocoronariens ou un remplacement valvulaire simple, l’administration intrathécale de morphine et sufentanil en dose unique satisfait les critères de chirurgie cardiaque “fast-track”.

Epidural and Intravenous Fentanyl Produce Equivalent Effects during Major Surgery

Background The benefit of epidural versus intravenous fentanyl administration for postoperative analgesia is controversial. In the current study, the intraoperative effects of epidural versus intravenous fentanyl administration were compared during major surgery. Methods Twenty elective patients scheduled for thoracoabdominal esophagectomy under general anesthesia with propofol infusion were randomly allocated to receive either intravenous or epidural boluses of 50–100 micro gram fentanyl in a double‐blind fashion to maintain hemodynamic stability. Plasma cortisol and fentanyl, as well as total urinary catecholamines, were obtained at the end of the operations. Results Hemodynamic variations were similar except that patients receiving epidural fentanyl had a lower incidence of heart rate reduction (> 20% reduction from baseline, P < 0.05). There were no differences in mean intraoperative fentanyl (1,115 + 430 and 1,010 + 377 micro gram, epidural and intravenous, respectively) or propofol (2,281 + 645 and 2,452 + 1,169 mg) doses, number of boluses of fentanyl (nine in both groups), plasma fentanyl concentration (1.13 plus/minus 0.4 and 1.02 plus/minus 0.46 ng/ml), or number of anesthesiologists correctly identifying the site of fentanyl administration. Similarly, there were no differences in plasma glucose (8.9 + 1.8 and 9.3 + 1.8 mM) and cortisol (696 + 446 and 846 + 257 mM), or urinary epinephrine (12 + 3.7 and 13.1 + 9.2, micro gram/sample) and norepinephrine (42.7 plus/minus 26.7 and 39.1 plus/minus 2.76, micro gram/sample). Conclusions There appears to be no clinical advantage to epidural administration of fentanyl over intravenous administration during anesthesia for major surgery.

Transfusion in the cardiac patient

Transfusion guidelines in patients with coexisting cardiac diseases are similar to the ones in patients without such comorbidity, in that allogeneic blood transfusions most often are indicated at hemoglobin levels of less than 6.0 g/dL and hardly ever at hemoglobin levels greater than 10 g/dL. In the hemoglobin range of 6 to 10 g/dL, signs of impaired oxygenation should serve as transfusion indications, and such signs may be reached at higher hemoglobin values than in healthy patients. An inadequate oxygenation may become manifest globally in the form of a general hemodynamic instability with a tendency to hypotension and tachycardia despite normovolemia or an oxygen extraction of greater than 50%. An inadequate oxygenation in the form of myocardial ischemia may be manifested by new ST-segment depressions of greater than 0.1 mV, new ST-segment elevations greater than 0.2 mV, or new wall motion abnormalities in transesophageal echocardiography. Institutional guidelines also should consider local logistic characteristics such as the level of knowledge of physician and nurse staff caring for patients and the level of surveillance possible justifying eventually higher hemoglobin transfusion triggers, particularly in the postoperative period.

Validity of an Arterial Pressure Waveform Analysis Device: Does the Puncture Site Play a Role in the Agreement With Intermittent Pulmonary Artery Catheter Thermodilution Measurements?

OBJECTIVE The measurement of cardiac output is a key element in the assessment of cardiac function. Recently, a pulse contour analysis-based device without need for calibration became available (FloTrac/Vigileo, Edwards Lifescience, Irvine, CA). This study was conducted to determine if there is an impact of the arterial catheter site and to investigate the accuracy of this system when compared with the pulmonary artery catheter using the bolus thermodilution technique (PAC). DESIGN Prospective study. SETTING The operating room of 1 university hospital. PARTICIPANTS Twenty patients undergoing cardiac surgery. INTERVENTIONS CO was determined in parallel by the use of the Flotrac/Vigileo systems in the radial and femoral position (CO_rad and CO_fem) and by PAC as the reference method. Data triplets were recorded at defined time points. The primary endpoint was the comparison of CO_rad and CO_fem, and the secondary endpoint was the comparison with the PAC. MEASUREMENTS AND MAIN RESULTS Seventy-eight simultaneous data recordings were obtained. The Bland-Altman analysis for CO_fem and CO_rad showed a bias of 0.46 L/min, precision was 0.85 L/min, and the percentage error was 34%. The Bland-Altman analysis for CO_rad and PAC showed a bias of -0.35 L/min, the precision was 1.88 L/min, and the percentage error was 76%. The Bland-Altman analysis for CO_fem and PAC showed a bias of 0.11 L/min, the precision was 1.8 L/min, and the percentage error was 69%. CONCLUSION The FloTrac/Vigileo system was shown to not produce exactly the same CO data when used in radial and femoral arteries, even though the percentage error was close to the clinically acceptable range. Thus, the impact of the introduction site of the arterial catheter is not negligible. The agreement with thermodilution was low.

Partial Inflow Occlusion Facilitates Accurate Deployment of Thoracic Aortic Endografts

Purpose: To present a maneuver consisting of temporary blockage of the venous return to the heart for accurate deployment of thoracic aortic endoprostheses. Technique: During endovascular repairs in the thoracic aorta, an occluding balloon was introduced through the femoral vein into the right atrium under transesophageal echocardiographic control. The venous return through the inferior vena cava was temporarily blocked to reduce aortic flow during device deployment. The technique was applied in 21 patients with various lesions of the thoracic aorta. Partial inflow occlusion resulted in a mean systolic pressure of 49±6 mmHg and lasted for 52±14 seconds. Cardiac function was comparable to the preocclusion state, and no arrhythmias or ischemic events were encountered. In 7 procedures, inotropic or vasoconstrictor support was necessary after deployment. No complications related to the venous system were observed. The endoprostheses were precisely deployed at the target site in all patients. Conclusions: The force of aortic flow often impairs precise deployment of thoracic endoprostheses, resulting in distal displacement. Partial inflow occlusion provides precise control over the extent and duration of the hypotensive period, allowing accurate deployment of thoracic endoprostheses.

Is our heart a well-designed pump? The heart along animal evolution

A carrier system for gases and nutrients became mandatory when primitive animals grew larger and developed different organs. The first circulatory systems are peristaltic tubes pushing slowly the haemolymph into an open vascular tree without capillaries (worms). Arthropods developed contractile bulges on the abdominal aorta assisted by accessory hearts for wings or legs and by abdominal respiratory motions. Two-chamber heart (atrium and ventricle) appeared among mollusks. Vertebrates have a multi-chamber heart and a closed circulation with capillaries. Their heart has two chambers in fishes, three chambers (two atria and one ventricle) in amphibians and reptiles, and four chambers in birds and mammals. The ventricle of reptiles is partially divided in two cavities by an interventricular septum, leaving only a communication of variable size leading to a variable shunt. Blood pressure increases progressively from 15 mmHg (worms) to 170/70 mmHg (birds) according to the increase in metabolic rate. When systemic pressure exceeds 50 mmHg, a lower pressure system appears for the circulation through gills or lungs in order to improve gas exchange. A four-chamber heart allows a complete separation of systemic and pulmonary circuits. This review describes the circulatory pumping systems used in the different classes of animals, their advantages and failures, and the way they have been modified with evolution.