[Diagnosis and management of acute mesenteric ischemia]. / Diagnostic et prise en charge des ischémies mésentériques aiguës.

The prevalence of significant splanchnic arterial stenoses is increasing, but remains mostly asymptomatic due to abundant collateral circulation. Acute insufficiency of mesenteric arterial blood flow accounts for 60 to 70% of cases of mesenteric ischemia and results mostly from a superior mesenteric embolus. Despite major advances have been achieved in understanding the pathogenic mechanisms of bowel ischemia, its prognosis remains dismal with mortality rates about 60%. The diagnosis of acute mesenteric ischemia depends upon a high clinical suspicion, especially in patients with known risk factors. Rapid diagnosis is essential to prevent intestinal infarction. However, early signs and symptoms of mesenteric ischemia are non specific, and definitive diagnosis often requires radiologic examinations. Early and liberal implementation of angiography has been the major advance over the past 30 years which allowed increasing diagnostic accuracy of acute mesenteric ischemia. CT and MR-based angiographic techniques have emerged as alternatives less invasive and more accurate to analyse splanchnic vessels and evaluate bowel infarction. The goal of treatment of patients with acute mesenteric ischemia is to restore intestinal oxygenation as quickly as possible after initial management that includes rapid hemodynamic monitoring and support. Surgery should not be delayed in patients suspected of having intestinal necrosis.

Pressure-controlled ventilation and intrabronchial pressure during one-lung ventilation.

BACKGROUND: Pressure-controlled ventilation (PCV) has been suggested to reduce peak airway pressure (P(peak)) and intrapulmonary shunt during one-lung ventilation (OLV) when compared with volume-controlled ventilation (VCV). At the same tidal volume (V(T)), the apparent difference in P(peak) is mainly related to the presence of a double-lumen tracheal tube. We tested the hypothesis that the decrease in P(peak) observed in the breathing circuit is not necessarily associated with a decrease in the bronchus of the dependent lung. METHODS: This observational study included 15 consecutive subjects who were ventilated with VCV followed by PCV at constant V(T). Airway pressure was measured simultaneously in the breathing circuit and main bronchus of the dependent lung after 20 min of ventilation. RESULTS: PCV induced a significant decrease in P(peak) [mean (sd)] measured in the breathing circuit [36 (4) to 26 (3) cm H(2)0, P<0.0001] and in the bronchus [23 (4) to 22 (3) cm H(2)O, P=0.01]. However, the interaction (ventilatory mode x site of measurement) revealed that the decrease in P(peak) was significantly higher in the circuit (P<0.0001). Although the mean percentage decrease in P(peak) was significant at both sites, the decrease was significantly lower in the bronchus [5 (6)% vs 29 (3)%, P<0.0001]. CONCLUSIONS: During PCV for OLV, the decrease in P(peak) is observed mainly in the respiratory circuit and is probably not clinically relevant in the bronchus of the dependent lung. This challenges the common clinical perception that PCV offers an advantage over VCV during OLV by reducing bronchial P(peak).

[Pupillary dilatation monitoring to evaluate acute remifentanil tolerance in cardiac surgery]. / Monitorage de la dilatation pupillaire dans l'évaluation d'une tolérance aiguë au rémifentanil en chirurgie cardiaque.

INTRODUCTION: Remifentanil is a powerful morphinic agonist often ordered for anaesthesia. The use of peroperative large doses of this opioid increases the risk to develop postoperative hyperalgesia and acute tolerance. But how early these effects can occur? Despite the fact that these effects could be masked during the preoperative time because of general anaesthesia, it seems they could occur precociously. In order to try to describe this time, this study evaluated the acute tolerance under general anaesthesia requiring large doses of remifentanil by using an effective peroperative monitoring of nociception: the continuous pupillary diameter monitoring. MATERIALS AND METHODS: In this prospective observational clinical study, a continuous infusion of remifentanil was started at a range of 0.3 microg/kg/min after induction of anaesthesia by using propofol (TIVA), remifentanil bolus and cisatracurium. The pupil monitoring started 10 min later (T+10 min) and lasted until the surgical incision (T+65 min). So, there was no surgical stimulus during this time. RESULTS: Thirty patients undergoing major cardiac or vascular surgery were included in this study. The continuous pupil diameter evaluation showed a significant increase of the pupil diameter from T+45 min. No significant variation of heart rate, blood pressure, bispectral index (BIS) values were observed. DISCUSSION: The development of acute remifentanil tolerance could possibly explain these results. If evaluations with continuous pupillary diameter monitoring are still limited, these results suggest that the use of powerful opioids such as remifentanil should be associated with a N-methyl-D-aspartate (NMDA) receptor antagonist agent, including short time administrations.

[Stomach rupture associated with noninvasive ventilation]. / Rupture gastrique au décours d'une séance de ventilation non invasive.

Noninvasive positive-pressure ventilation (NIPPV) is a safe method to treat acute respiratory failure and is known to decrease the need for intubation and the length of ICU-stay. Few severe complications have been reported even when the indications are respected. Some rare cases of gastric distension were recently described. We report the case of a gastric perforation associated with NIPPV. The treatment was closure with a primary interrupted two-layer suture. Recovery was complete and the patient was transferred to the ward on Day 11.

[Effectiveness of a recruitment manoeuvre and positive end-expiratory pressure on respiratory mechanics during laparoscopic bariatric surgery]. / Efficacité d'une manoeuvre de recrutement alvéolaire associée à une pression expiratoire positive sur la mécanique respiratoire en coeliochirurgie bariatrique.

OBJECTIVE: To evaluate recruitment manoeuvre (RM) efficiency associated with a 10 cmH(2)O positive end expiratory pressure (PEEP) on respiratory mechanic estimated by lung compliance (Ctp) and PEEP to ZEEP expiratory volume delta (Delta VTE) during laparoscopic bariatric surgery in patients with morbid obesity. STUDY DESIGN: Prospective randomized study. METHODS: Twenty-six obese patients (BMI>40 kg/m(2)) undergoing laparoscopic bariatric surgery. The recruitment group received an RM followed by a 10 cmH(2)O PEP versus only 10 cmH(2)O PEP in the control group. Ctp was measured during the intervention and functional residual capacity (FRC) was estimated measuring Delta VTE during a PEP to ZEP manoeuvre. Mann and Whitney tests as well as a t-test were used (significance p<0.05). RESULTS: In the RM group, a significant improvement of 52+/-14 ml/cmH(2)O was noted versus a 36+/-10 ml/cmH(2)O in the PEP group (p=0,004). This improvement was transitory and no statistically significant Delta VTE difference was noted between the groups at the end of the intervention (360 [90-770]ml [MRA] and 310 [190-450]ml [PEP]). CONCLUSION: In patients with morbid obesity undergoing laparoscopic bariatric surgery, an RM conducted prior the pneumoperitoneum temporarily improves lung mechanics but without any change of the end expiratory lung volume at the end of the surgery in comparison with PEP alone. The RM was well tolerated.

Safety of HES 130/0.4 (Voluven(R)) in patients with preoperative renal dysfunction undergoing abdominal aortic surgery: a prospective, randomized, controlled, parallel-group multicentre trial.

BACKGROUND AND OBJECTIVE: Patients with impaired renal function are at risk of developing renal dysfunction after abdominal aortic surgery. This study investigated the safety profile of a recent medium-molecular-weight hydroxyethyl starch (HES) preparation with a low molar substitution (HES 130/0.4) in this sensitive patient group. METHODS: Sixty-five patients were randomly allocated to receive either 6% hydroxyethyl starch (Voluven); n = 32) or 3% gelatin (Plasmion); n = 33) for perioperative volume substitution. At baseline, renal function was impaired in all study patients as indicated by a measured creatinine clearance < 80 mL min(-1). The main renal safety parameter was the peak increase in serum creatinine up to day 6 after surgery. RESULTS: Both treatment groups were compared for non-inferiority (pre-defined non-inferiority range hydroxyethyl starch < gelatin + 17.68 micromol L(-1) or 0.2 mg dL(-1). Other renal safety parameters included minimum postoperative creatinine clearance, incidence of oliguria and adverse events of the renal system. Baseline characteristics, surgical procedures and the mean total infusion volume were comparable. Non-inferiority of hydroxyethyl starch vs. gelatin could be shown by means of the appropriate non-parametric one-sided 95% CI for the difference hydroxyethyl starch-gelatin [-infinity, 11 micromol L(-1)]. Oliguria was encountered in three patients of the hydroxyethyl starch and four of the gelatin treatment group. One patient receiving gelatin required dialysis secondary to surgical complications. Two patients of each treatment group died. CONCLUSION: As we found no drug-related adverse effects of hydroxyethyl starch on renal function, we conclude that the choice of the colloid had no impact on renal safety parameters and outcome in patients with decreased renal function undergoing elective abdominal aortic surgery.

Acute kidney injury in the ICU: time has come for an early biomarker kit!

Early recognition of acute kidney injury (AKI) in the intensive care unit (ICU) remains a critical problem, with a rising incidence and a high mortality rate. As a consequence, the actual lack of an early and effective biomarker results in a significant delay in initiating appropriate therapy. The accurate diagnosis of AKI is especially problematic in critically-ill patients, in whom we know that renal function is in an unsteady state; therefore the validity of creatinine-based baseline assessment measures is reduced. Because the rationale for assessing AKI markers in critically-ill patients is strong at the present time, researchers are stimulated to establish a multidimensional AKI classification system. This system should in essence grade AKI severity. The most widely referenced classification is the RIFLE system. Thus, early recognition of AKI, well before changes in serum creatinine occur, has come under intensive research, because it is evidenced that even small increases in serum creatinine are associated with an increase in patient mortality. The development of a biomarker kit in which several early markers with different characteristics are combined, is essential. Multi-centre, randomized studies indicate a potential for early biomarkers able to diagnose AKI 48 hours before creatinine changes. In conclusion, time has come to leave serum creatinine behind as a marker of renal function in patients with AKI on the ICU. Only then will we be able to offer early goal-directed therapy for the kidney in the ICU setting.

[Perioperative anticoagulation management for prosthetic heart valves]. / Gestion en période périopératoire de l'anticoagulation des valves prothétiques cardiaques.

OBJECTIVES: The practices and the guidelines over the perioperative management of the anticoagulation of patients with cardiac valves prothesis are the object of no consensual attitude. The thrombotic risk over the time is well known. It depends of the type or the location on the valve, of their associations and the age of the patient. In the perioperative period, the antithrombotic treatment must be interrupted according to the surgical haemorrhagic risk. STUDY DESIGN: Short review. RESULTS: Only patients, without associated risk factor, carriers of bioprosthesis from more than 3 months, can be maintained only under antiplatelets agents. In others situations, the caution imposes a bridge of anticoagulants from 48 to 72 hours with unfractionated heparin (subcutaneous at home, intravenous at the hospital). Low molecular weight heparin has no commercial authorization in this indication. The resumption of the anticoagulation by unfractionated heparin in postoperative period must be the most premature possible after the decrease of the surgical bleeding. The relay by vitamin K antagonists has to be made over 48 to 72 hours. Within the framework of the urgency, the surgical haemorrhagic risk is weak for an INR <1.5. According to the urgency of the surgery, a treatment by vitamin K (if the delay is over 12 hours) or by prothrombinic complex allows to correct this INR. The identification of thrombotic complications requires a particular attention. In the postoperative period, as soon as there is suspicion of thrombosis, clinical manifestations must be consolidated by the practice of a transoesophageal echography, which only confirm the diagnosis.

Propofol sedation using Diprifusor target-controlled infusion in adult intensive care unit patients.

This multicentre, non-comparative study investigated the range of target blood propofol concentrations required to sedate 122 adult intensive care patients when propofol was administered using Diprifusor target-controlled infusion systems together with opioid analgesia. Depth of sedation was assessed with a modified Ramsay score and the target blood propofol setting was adjusted to achieve the sedation desired for each patient. A desired level of sedation was achieved for 84% of the sedation period. In postcardiac surgery patients the median time-weighted average propofol target setting was 1.34 microg.ml(-1) (10th - 90th percentiles: 0.79-1.93 microg.ml(-1)). Values in brain injured and general ICU patients were 0.98 (10th - 90th percentiles: 0.60-2.55) microg.ml(-1) and 0.42 (10th - 90th percentiles: 0.16-1.19) microg.ml(-1), respectively. Measured propofol concentrations were generally close to values predicted by the Diprifusor system. Target settings in the range of 0.2-2.0 microg.ml(-1) are proposed for propofol sedation in this setting with titration as required in individual patients.

Changes in type B natriuretic peptide (BNP) concentrations during cardiac valve replacement.

OBJECTIVE: The aim of our study was to investigate the ability of BNP levels to reveal the immediate post-surgery cardiac function improvement. We measured the perioperative variations in BNP concentrations in patients scheduled for cardiac surgery with cardiopulmonary bypass (CPB), chronic mitral regurgitation, valvular aortic stenosis, or myocardial ischaemia. METHODS: Three groups were included: patients with coronary artery bypass graft (CABG, group I, n = 14), aortic (AVR, group II, n = 14) or mitral (MVR, group III, n = 7) valve replacement. BNP assay was performed at the induction of anesthesia, immediately after the CPB, at the arrival in the intensive care unit, 4 h, 8 h and 12 h after the arrival in ICU. RESULTS AND CONCLUSION: The occurring variation in BNP levels after the operation is an increase whatever the corrective surgery, underlying the relative lack of specificity of BNP with regard to the cardiac pathology. Besides iatrogenic cardioplegia one can supposes that cardiac surgery involves other major stimuli such as anesthesia, sternotomia, hemodynamics, post-operative that could influence in a non specific way BNP levels.

["Optigo" hand-held echocardiography in post-surgery of coronary artery bypass graft]. / Intérêt de l'échocardiographe portatif Optigo en période postopérative de chirurgie coronarienne.

INTRODUCTION: After all the advances in electronic miniaturization, first hand-held echocardiographs have finally appeared in echocardiographic laboratories. However, questions still remain about their usefulness in our everyday practice and also about their good diagnosis accuracy. Since some of them do not offer modes such as pulsed or continuous wave Doppler, nor M-mode, they cannot compete with conventional devices. However, they do offer advantages such as their long autonomy, the good quality of their image as well as the one obtained with colour-Doppler mode, in addition obviously to the fact that they can be carried around very easily. OBJECTIVES: To better define their possible uses, we assessed capabilities of one of them, the Optigo (Philips Ultrasound) to analyse patients who had undergone coronary artery bypass surgery. METHOD: Fifty patients have been included in this study few days after the surgery. Each of the patients had two echocardiographic examinations, one with a conventional device and one with the Optigo. Two separated and blinded observers for a subsequent and side-by-side criteria comparison performed the two echocardiograms. RESULTS: Hand-held echocardiography had a good diagnosis accuracy varying from 85% to 95% depending on the analysed criteria. It was more specifically good in the analysis of global or regional left heart function and of the right cavities as well as detecting the existence of pericardial effusion. CONCLUSION: Hand-held echocardiographic device demonstrated high accuracy in assessing patients with recent coronary bypass surgery especially regarding cardiac function and pericardial effusion diagnosis.

[Is length of stay in the recovery room a risk factor for cross infections?]. / Le séjour en salle de surveillance postinterventionnelle peut-il être à l'origine de transmissions croisées?

OBJECTIVE: To assess cross contamination for patients at the time of their stay in the recovery room (RR). STUDY DESIGN: Prospective study. PATIENTS AND METHODS: A prospective survey over 3 weeks with 75 adult patients admitted to RR after thoracic or neck surgery. Samples for bacterial analysis were systematically taken from all patients before they left the operating theatre and just before discharge of RR (nose-throat and skin adjacent to the surgical wound). During this period, hand's health care workers (HCW) and environmental surfaces were sampled. RESULTS: There were 3 groups of patients: endoscopy (41%), thoracic surgery (39%). And thyroidectomy (20%), 392 samples were analysed. Potentially pathogenic floras were found on the admission for 25 patients and at discharge for 31 patients. A pathogenic flora was detected at discharge in 13 patients, whereas none was found at admission in RR. These patients were principally in the thyroidectomy group and their stay in RR was longer than 20 minutes. There is no significant difference concerning the nosocomial risk between 3 groups. Pathogenic flora was found in 19% of HCW (8 of 42). CONCLUSION: Cross contamination can exist in recovery room and educative measures are to be taken regarding handwhashing, isolation precautions and environmental cleaning.

Platelet function point-of-care tests in post-bypass cardiac surgery: are they relevant?

BACKGROUND: Platelet dysfunction is an important cause of excessive bleeding after cardiac surgery. We assessed two platelet function point-of-care tests: the platelet function analyser (PFA-100) and the Hemostatus(TM) in patients with and without excessive bleeding after cardiac surgery with cardiopulmonary bypass. METHODS: Mediastinal chest tube drainage (MCTD) was measured for the first 6 h in the intensive care unit (ICU). Haematology and coagulation tests were done on arrival in the ICU, and when excessive bleeding occurred (MCTD >1 ml kg(-1) h(-1)) or after 3 h. RESULTS: Eighteen patients bled excessively and 27 had normal MCTD. Hemostatus measurements were prolonged in those with excessive bleeding compared with the normal group. The times for PFA-100 adenosine diphosphate (ADP) and epinephrine were 91 vs 71 s (P=0.004) and 155 vs 114 s (P=0.02) in the bleeding and normal group s, respectively. None of the Hemostatus or PFA-100 values correlated with total MCTD. Depending on the agonist used, maximum aggregation was 33-81% and 52-86% in bleeding and normal groups, respectively. Only poor correlations were found between PFA-100 epinephrine and maximum aggregation in response to ADP (r=-0.52, P=0.03) or to collagen (r=-0.48, P=0.04). CONCLUSION: Patients bleeding excessively in the ICU had abnormal measurements in point-of-care tests without a dramatic decrease in aggregation. Except for patients with increased risk of postbypass bleeding, point-of-care tests are not useful for routine use after cardiac surgery.

[Reproducibility and interchangeability of the Thromboelastograph, Sonoclot and Hemochron activated coagulation time in cardiac surgery]. / Reproductibilité et interchangeabilité du Thromboélastographe, Sonoclot et du temps de coagulation activé (Hémochron), en chirurgie cardiaque

PURPOSE: Despite their common use in cardiac surgery, few studies have evaluated the reproducibility of the Thromboelastograph (TEG), of the Sonoclot (SCT), and of the activated coagulation time with celite (ACT-C) or kaolin (ACT-K) measured with the Hemochron, in clinical conditions of on-site monitoring of hemostasis. This study determined the reproducibility of those measurements, and evaluated the ability of various devices to substitute for the ACT-C. METHODS: Blood samples collected from 20 volunteers and 21 patients undergoing myocardial revascularization were analyzed in the two channels of the TEG, in two SCT and four Hemochron analyzers. The overall of TEG and SCT coagulation profiles were analyzed by a computerized TEG and an experienced observer respectively. The variation rate (V%) was calculated for each variable. The ability of ACT-K and SCT to substitute for ACT-C under different clinical conditions was evaluated. RESULTS: ACT-C and ACT-K V% ranged between 5.6% and 10.8% and between 6.7% and 12.4% respectively. TEG and SCT V% ranged between 3.1% and 9.5% and between 5.8% and 33.6% respectively, according to different conditions and parameters. In volunteers and non-heparinized patients, the ACT-C and ACT-K were interchangeable. No other test can substitute for the ACT-C when patients are heparinized during cardiopulmonary bypass (CPB). CONCLUSIONS: In the clinical conditions of use, on-site hemostasis monitoring devices providing the most reproducible measurements are, in decreasing order, the TEG, the Hemochron and the SCT. In heparinized patients and during CPB, results from different tests are not interchangeable, stressing the importance of establishing appropriate instrument-specific values for monitoring anticoagulation during cardiac surgery.

Inhibition of platelet aggregation by abciximab but not by aspirin can be detected by a new point-of-care test, the hemostatus.

We have investigated the type of platelet defect that can be detected with the Hemostatus test performed with the Hepcon/HMS instrument (Medtronic) designed to investigate platelet function during and after surgery. This assay is based on the comparison of the activated clotting time of whole blood measured in cartridges containing kaolin or kaolin and platelet-activating factor in different concentrations. Addition of platelet-activating factor shortened the blood activated clotting time when the platelet counts were normal. However, when platelet counts were below 70000/microL, the activated clotting time was prolonged in all channels including those without platelet-activating factor showing the influence of platelets in the formation of the clot under the conditions tested. Inhibition of platelet aggregation with c7E3 (abciximab, ReoPro) also induced a much-prolonged activated clotting time, and a similar finding was seen with blood from a patient with Glanzmann's thrombasthenia confirming the need for platelet aggregation and/or the glycoprotein (GP) IIb-IIIa complex. In contrast, the interaction of GP Ib with von Willebrand Factor was not of major importance, since inhibition of this interaction with the anti-GP Ib murine monoclonal antibody, ALMA-12, did not modify the activated clotting time. Furthermore, the activated clotting time measured for patients with an acquired defect in von Willebrand Factor activity were unchanged. Finally, inhibition of thromboxane A2 formation by aspirin did not influence the results of this test. Globally, the Hemostatus test was able to detect major abnormalities of GP IIb-IIIa function in the presence or absence of platelet-activating factor.

[Cellular energy metabolism: physiologic and pathologic aspects]. / Métabolisme énergétique cellulaire: aspects physiologiques et pathologiques.

Cellular homeostasis requires permanent energy production and consumption. Adenosine triphosphate (ATP) is the major energy component for the cell. Its synthesis occurs mainly in mitochondria where the oxidative phosphorylations realise the coupling between oxygen consumption and phosphorylation of adenosine diphosphate. The anaerobic production of ATP plays an important role in the intermediary metabolism. The enzymatic complexes of the mitochondrial respiratory chain are energy transducers acting as proton pumps. In cardiomyocytes, the phosphocreatine circuit allows a substrate channelling between mitochondria and myofibrils. This metabolic compartmentation explains the difficulties of studying energetic metabolism in the beating heart and the lack of correlation between cardiac function and the usual energy parameters. Mitochondria are a potential site of action of anaesthetic agents. Lipophilic local anaesthetics impair cellular energy metabolism and mitochondrial ATP production. Such effects could be associated with toxic effects of these molecules. NMR or near-infrared spectroscopy are non invasive techniques for monitoring energetic metabolism in vivo. Clinical applications are developed for analysing brain, muscle or cardiac function in physiological and pathological conditions.

[Preoperative evaluation of hemorrhagic risk]. / Evaluation préopératoire du risque hémorragique.

Evaluation of bleeding risk before surgery requires both precise knowledge of epidemiological data relating to haemostasis disorders and a true clinical approach to help guide the diagnosis. The patient's individual and familial history is recovered during both the interview with the anaesthesiologist and the clinical examination. Preoperative haemorrhage risk prevalence is 1/40,000 patients in patients with asymptomatic congenital haemostasis disorders with low bleeding and 1/2,000 patients for acquired asymptomatic haemostasis disorders. Deficits in haemostasis factors, i.e., congenital disorders with haemorrhage potential, have an overall prevalence of 1/6,500 patients. Whatever the clinical case, haemorrhage disorders will arise in patients with either congenital or acquired bleeding abnormalities without symptoms. To work in close collaboration with haemobiologists and to request appropriate biological screening tests, it is therefore important to take into account prevalence data according to the surgical environment from which the patient will benefit.

[Left ventricular diastolic function: physiology, physiopathology, evaluation, therapy, consequences of anesthesia]. / Fonction diastolique ventriculaire gauche: physiologie, physiopathologie, évaluation, moyens thérapeutiques, incidences en anesthésie.

With the exception of cardiac surgery, the acute disturbance of the left ventricular diastole occurs mainly in the elderly. Today it represents 30 to 40% of congestive cardiac failures, however with a lower mortality than for acute systolic disturbances. Generally indicated are relaxation anomalies, proto-mesodiastolic mechanism and problems with compliance, an indicator of the pressure/volume diastolic relationship. Invasive techniques remain the standard method. Doppler echocardiography is becoming increasingly important for the assessment of diastolic function. In most cardiopathies, relaxation anomalies occur early, whereas compliance disturbances are mainly associated with advanced cardiac diseases. During anaesthesia, adverse events (auricular fibrillation, hypovolaemia) may worsen a fragile situation. Anaesthetic agents, in particular volatile agents, act on the ventricular diastole. Long-term therapy of diastolic anomalies includes agents amending left ventricular hypertrophy. Emergency therapy has not yet been systematised.