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Biomedical subjects

V Piriou

Publications and source records attributed to V Piriou.

At least 19 recordsLinked to original sources
PubMed2006

[Coronary stents and anaesthesia: it is time to have national data].

We report 13 cases of coronary stent patients, undergoing a non cardiac surgery. Despite an heterogenous perioperative management of antiplatelet agents, none of these patients developed any significant complications. Recently, several case reports of postoperative drug eluting stent thrombosis have been reported. However, the actual incidence of this dramatic event is not known. This confirms the need to perform prospective studies or registries of patients with coronary stents undergoing non cardiac surgery, in order to propose evidence-based recommendations on perioperative antiplatelet management in such patients.

Aged↗
PubMed2006

[Transorbital fiberoptic intubation: a predictable difficult intubation in cephalic surgery].

Management of the difficult adult airway is a crucial problem in anaesthesia. It is the first cause of anaesthetic mortality and morbidity. We report here the case of a patient who could only be intubated through the orbital cavity. We discuss our technique of intubation compared to the other rare procedures described in the literature. We also focus on our anaesthetic protocol and the interest of preserving spontaneous ventilation for intubation. Use of short acting anaesthetic drugs can help to achieve such conditions.

Adenocarcinoma↗
PubMed2006

Effects of increased intra-abdominal pressure on central circulation.

BACKGROUND: In an experimental model we investigated the effects of a gradual increase in intra-abdominal pressure (IAP) on the central circulation. METHODS: Seven pigs were anaesthetized, mechanically ventilated and instrumented. IAP was gradually increased by 5 mm Hg up to 30 mm Hg by abdominal banding in normovolaemic animals, and then they were made hypovolaemic after blood withdrawal. Right atrial pressure (RAP) and left ventricular end-diastolic pressure (LVEDP) at each step and aortic, femoral and inferior vena cava blood flows were measured. Left ventricular end-diastolic area (LVEDA) was determined using epicardial echocardiography. RESULTS: Cardiac output maintained at mild IAP was reduced to 76 (24)% of the initial value at 30 mm Hg IAP [mean (sd)] in normovolaemic animals, and 72 (22)% (P<0.001) in hypovolaemic animals. In normovolaemic animals the LVEDA and LVEDP were significantly increased at an IAP of 10 and 15 mm Hg by 26 (24)% and 38 (23)%, respectively. At these IAP values, the difference between the RAP and IAP was positive. When this gradient became negative, that is beyond 15 mm Hg in normovolaemia and for all IAP values in hypovolaemic animals, the LVEDA declined, reaching 78 (16)% and 62 (22)% (P<0.05) of the initial values in normovolaemic and hypovolaemic groups at the highest IAP value. CONCLUSIONS: These results showed that a gradual increase in IAP led to a redistribution of abdominal blood volume towards the thoracic compartment, at IAP lower than 15 mm Hg in normovolaemia, and at its expense at higher values of IAP. In hypovolaemia there was no thoracic compartment gain. Whereas the absolute or transmural RAPs were not informative of the direction of this blood shift, an RAP greater than IAP was associated with an intrathoracic compartment gain.

Abdomen↗
PubMed2005

[Anaesthetic-induced myocardial preconditioning: fundamental basis and clinical implications].

OBJECTIVE: Volatile halogenated anaesthetics offer a myocardial protection when they are administrated before a myocardial ischaemia. Cellular mechanisms involved in anaesthetic preconditioning are now better understood. The objectives of this review are to understand the anaesthetic-induced preconditioning underlying mechanisms and to know the clinical implications. DATA SOURCES: References were obtained from PubMed data bank (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi) using the following keywords: volatile anaesthetic, isoflurane, halothane, sevoflurane, desflurane, preconditioning, protection, myocardium. DATA SYNTHESIS: Ischaemic preconditioning (PC) is a myocardial endogenous protection against ischaemia. It has been described as one or several short ischaemia before a sustained ischemia. These short ischaemia trigger a protective signal against this longer ischaemia. An ischemic organ is able to precondition a remote organ. It is possible to replace the short ischaemia by a preadministration of halogenated volatile anaesthetic with the same protective effect, this is called anaesthetic PC (APC). APC and ischaemic PC share similar underlying biochemical mechanisms including protein kinase C, tyrosine kinase activation and mitochondrial and sarcolemnal K(ATP) channels opening. All halogenated anaesthetics can produce an anaesthetic PC effect. Myocardial protection during reperfusion, after the long ischaemia, has been shown by successive short ischaemia or volatile anaesthetic administration, this is called postconditioning. Ischaemic PC has been described in humans in 1993. Clinical studies in human cardiac surgery have shown the possibility of anaesthetic PC with volatile anaesthetics. These studies have shown a decrease of postoperative troponin in patient receiving halogenated anaesthetics.

Anesthetics, Inhalation↗
PubMed2005

[Prevention of venous thromboembolism following cardiac, vascular or thoracic surgery].

In the absence of thromboprophylaxis, coronary artery bypass graft surgery (CABG), intrathoracic surgery (thoracotomy or video-assisted thoracoscopy), abdominal aortic surgery and infrainguinal vascular surgery are high-risk surgeries for the development of venous thromboembolic events (VTE). The incidence of VTE following surgery of the intrathoracic aorta, carotid endarterectomy or mediastinoscopy is unknown. Data from the litterature are lacking to draw evidence-based recommandations for venous thromboprophylaxis after these three types of surgeries, and the following guidelines are but experts'opinions (Grade D recommendations). Thromboprophylaxis is recommended after CABG (Grade D), with either subcutaneous (SC) low molecular weight heparin (LMWH) or SC or intravenous (i.v.) unfractioned heparin (UH) (PTT target = 1.1-1.5 time control value) (both grade D). This may be combined with the use of intermittent pneumatic compression device (Grade B). After valve surgery. The anticoagulation recommended to prevent valve thrombosis is sufficient in order to prevent VTE. We recommend thromboprophylaxis with either LMWH or low dose UH to prevent VTE after aortic or lower limbs infrainguinal vascular surgery (both grade B and D). Vitamine K antagonists (VKA) are not recommended in this indication (Grade D). We recommend thromprophylaxis following intrathoracic surgery via thoracotomy or videoassisted thoracoscopy (grade C). Either subcutaneous LMWH or subcutaneous or i.v. low dose UH may be used (Grade C). Efficacy of intermittent pneumatic compression device has been demonstrated in a study (grade C). VKA are not recommended (grade D). No further recommendation regarding the duration of thromboprophylaxis after these three types of surgeries can be made.

Anesthesia↗
PubMed2004

[Perioperative administration of betablockers: a practice survey].

OBJECTIVES: To evaluate the anaesthesiologists' attitude concerning the perioperative administration of betablockers (BB), especially prophylactic BB, in order to prevent postoperative cardiac complications. METHODS: A questionnaire including 20 items was sent to 700 anaesthesiologists of 4 French departments (Ain, Isere, Loire et Rhone). RESULTS: The response rate was 30%. Eighty-eight percent of respondents prescribed the BB with the premedication, on the day of the surgery in patients who were on regular BB. Before major surgery, 37% percent of respondents always or usually introduced prophylactic BB in patients with high cardiac risk. Atenolol was the drug of choice for 68% of perioperative BB users. Seventy-one percent of anaesthesiologists using prophylactic BB asked for a cardiologic opinion before starting BB therapy. CONCLUSION: In practice, anaesthesiologists continued BB during the perioperative period in patients who were on chronic treatment with BB. However, prophylactic perioperative administration of BB in patients with high cardiac risk is still inadequate and dependent on a cardiologic opinion.

Adrenergic beta-Antagonists↗
PubMed2004

[Ischaemia of the lower limbs: anaesthesia and intensive care].

OBJECTIVES: To appreciate the severity of a patient with acute limb ischaemia, to know how to manage these patients during the perioperative period. DATA SOURCES: References were obtained from PubMed data bank (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi) using the following keywords: acute limb, ischaemia, prognosis, complications, rhabdomyolysis, hyperkalaemia, compartment syndrome, fasciotomy. DATA SYNTHESIS: Ischaemia of the lower limbs is a medico-surgical emergency. The ischaemia implies a decrease of cellular energetic stocks and an increase in intracellular calcium. During reperfusion, the calcium paradox is exacerbated and ROS formation produces membrane damage. Tissue oedema and a local and general inflammatory syndrome occur. Clinical symptoms of acute ischaemia include pallor, pulselessness, decrease of temperature and pain. Occurrence of neurological symptoms is a sign of severity. Prognosis of patients relates directly to preexisting collateral circulation, aetiology of the occlusion (thrombosis vs embolus), duration of ischaemia, topography of the occlusion (severity of proximal occlusions as the acute aortic occlusion), and co-morbidity (renal failure, heart failure). The temperature of the ischaemic limb, quality of the downstream circulation, extension of the thrombus, arterial pressure and association to a venous thrombosis are other prognostic factors of lower limb ischaemia. The first treatment to be initiated is high doses of heparin. Once the diagnosis is made, the number of preoperative tests will be as small as possible because of the urgency of revascularization. Arteriography will be performed only when really needed and when its realization will not delay revascularization and will not alter the patient's prognosis. Where general anesthesia is required, the choice of anaesthetic agents will be based on their haemodynamic stability. During severe acute limb ischaemia, monitoring of invasive pressure is recommended, as well as regular dosages of potassium, arterial gases and CPK. Preoperatively in case of severe ischaemia, (proximal occlusion lasting more than 6 hours), preventive treatment, including controlled reperfusion with heparinized serum is indicated. Surveillance and prevention of a rhabdomyolysis and renal failure are imperative. Immediately after reperfusion, a dosage of potassium must be performed; moreover that hyperkalaemia is favoured by acidosis or renal failure. Postoperative haemodialysis is performed in case of hyperkalaemia or renal failure. Occurrence of compartment syndrome has to be checked and fasciotomy must be performed in case of a doubt on the microcirculation integrity.

Acute Disease↗
PubMed2002

Pharmacological preconditioning: comparison of desflurane, sevoflurane, isoflurane and halothane in rabbit myocardium.

BACKGROUND: Recent investigations showed that isoflurane can induce pharmacological preconditioning. The present study aimed to compare the potency of four different halogenated anaesthetics to induce preconditioning. METHODS: Anaesthetized open-chest rabbits underwent 30 min of coronary artery occlusion followed by 3 h of reperfusion. Before this, rabbits were randomized into one of five groups and underwent a treatment period consisting of either no intervention for 45 min (control; n = 10), or 30 min of 1 MAC halogenated anaesthetic inhalation followed by 15 min of washout. End-tidal concentrations of halogenated agents were 3.7% for sevoflurane (n = 11), 1.4% for halothane (n = 9), 2.0% for isoflurane (n = 11), and 8.9% for desflurane (n = 11). Area at risk and infarct size were assessed by blue dye injection and tetrazolium chloride staining. RESULTS: Mean (SD) infarct size was 54 (18)% of the risk area in untreated controls and 40 (18)% in the sevoflurane group (P > 0.05, ns). In contrast, mean infarct size was significantly smaller in the halothane, isoflurane, and desflurane groups: 26 (18)%, 32 (18)% and 16 (17)%, respectively (P < 0.05 vs control). CONCLUSIONS: Halothane, isoflurane and desflurane induced pharmacological preconditioning, whereas sevoflurane had no significant effect. In this preparation, desflurane was the most effective agent at preconditioning the myocardium against ischaemia.

Anesthetics, Inhalation↗
PubMed2001

Cardiac surgery with cardiopulmonary bypass in patients with type II heparin-induced thrombocytopenia.

BACKGROUND: The use of cardiopulmonary bypass (CPB) in patients with a history of type II heparin-induced thrombocytopenia (HIT) may be associated with complications related to their anticoagulation management. METHODS: Between January 1997 and December 1999, among 4,850 adults patients who underwent cardiac surgery in our institution, 10 patients presented with preoperative type II HIT. In 4 patients, anticoagulation during CPB was achieved with danaparoid sodium. In 6 other patients, heparin sodium was used after pretreatment with epoprostenol sodium. RESULTS: No significant change in platelet count occurred in any patient. No intraoperative thrombotic complication was encountered. Total postoperative chest drainage ranged from 250 to 1,100 ml in patients pretreated with epoprostenol and 1,700 to 2,470 ml in patients who received danaparoid sodium during CPB (p < 0.05, Mann-Whitney U test). CONCLUSIONS: During CPB, inhibition of platelet aggregation by prostacyclin may be a safe anticoagulation approach in patients with type II HIT.

Aged↗
PubMed2000

Opposite effects of halothane on guinea-pig ventricular action potential duration.

Halothane protects the heart against the reperfusion injury observed after an ischemia. In ischemic or anoxic conditions, a large ATP-sensitive K(+) (K(ATP)) conductance is supposed to provide an endogenous protection to the myocardium. In this study, we tested the possibility that halothane acted by modulating this conductance. Isolated guinea-pig cardiomyocytes were successively studied in current clamp and in voltage-clamp conditions. Action potentials regulation by halothane was tested in control conditions and in situations where the K(ATP) channels were activated. In control conditions, halothane decreased action potential duration of myocytes but did not significantly alter the inward rectifying K(+) current. Conversely, halothane lengthened action potential of cells in which the K(ATP) conductance was activated, by inhibiting the K(ATP) current. In ischemic conditions, simultaneous shortening of long action potentials and lengthening of shortened ones would be expected to homogenize the absolute refractory period at the border between normoxic and anoxic zones. This effect, together with a decrease in calcium load, could protect the myocardium against re-entrant arrhythmias.

Action Potentials↗
PubMed2000

[Perioperative beta-blockers. Part one: fundamentals].

PURPOSE: To review the pharmacologic and pathophysiologic information necessary to prescribe beta-blockers (BB) in perioperative medicine. DATA SOURCE: Manual retrieval and electronic research of the literature using MEDLINE (key-words: anesthesia and beta- blocker; surgery and beta-blocker). DATA SYNTHESIS: Cardioselective BB inhibit preferentially beta-1 receptors, inducing a decrease in heart rate and cardiac inotropism leading to reduction of oxygen myocardial consumption. Non-cardioselective BB inhibit also beta-2 receptors, increasing bronchial and peripheral vascular resistances and uterine contractions. However, some BB are also vasodilators (carvedilol, celiprolol, labetalol). Contraindications to BB result logically from their pharmacological effects. Treatment with BB increases membrane beta-receptor density; this explains sympathetic overactivity observed during weaning of treatment. Since the discovery of propranolol in 1964, the use of BB has been controversial in anesthesia. Formerly, the adverse effects of partial sympatholysis during anesthesia and surgery were feared. However, since 1973, experimental and clinical data have suggested a protective hemodynamic effect. CONCLUSION: Continued administration of BB up to the time of anesthesia has been encouraged except in patients with signs of intolerance such as hypotension or excessive bradycardia.

Adrenergic beta-Antagonists↗
PubMed2000

[Perioperative beta-blockers. Part two: therapeutic indications].

PURPOSE: To review the pharmacologic and pathophysiologic information necessary to prescribe beta-blockers (BB) in perioperative medicine. DATA SOURCE: Manual retrieval and electronic research of the literature using MEDLINE (key-words: anesthesia and beta- blocker; surgery and beta-blocker). DATA SYNTHESIS: In non cardiac surgery, the beneficial effects of BB have been demonstrated in hypertensive patients since 1979. In 1996, the beneficial effects of atenolol in patients with coronary artery disease (reduction of postoperative myocardial ischemia and overall reduction in two-year mortality) were demonstrated. In coronary surgery, the interest of preoperative BB treatment has been shown since 1983. Administration of BB has been shown to be beneficial in acute myocardial infarction or chronic cardiac failure (except in NYHA class IV patients). CONCLUSION: BB have been shown to exert a beneficial effect on postoperative outcomes in patients with cardiovascular disease or risk factors, and their more widespread use in perioperative medicine is encouraged.

Adrenergic beta-Antagonists↗
PubMed2000

Biphasic response after brain death induction: prominent part of catecholamines release in this phenomenon.

BACKGROUND: The physiopathology of hemodynamic instability that occurs after brain death remains unknown. The aim of this study was to examine the initial response to brain death induction. METHODS: After anesthesia and monitoring, 16 pigs were randomized into a control group (C, n = 8) and a brain death group (BD, n = 8). We inflated a subdural catheter balloon to induce brain death. We analyzed hemodynamic and plasmatic biochemical data for 180 minutes after brain death induction. Energetic compounds were measured. We expressed the results in comparison with the C group. RESULTS: The C group remained stable. One minute after brain death, the Cushing reflex appeared, with a hyperdynamic response to plasma catecholamines levels increasing (norepinephrine and epinephrine, 3.1-fold, p = 0. 02, and 3.8-fold, p = 0.07, respectively). After a return to baseline, we recorded a second hyperdynamic profile 120 minutes later. At this time, a second peak of catecholamines appeared (6. 3-fold, p = 0.04, and 9.1-fold, p = 0.02, concerning norepinephrine and epinephrine). At the same time, we observed brief myocardial lactate production (+175%, p < 0.01), with a rise of troponine I (+64%, p = 0.03). The energetic index was similar in both groups: 0. 85 (+/-0.02) in the C group vs 0.87 (+/-0.02) in the BD group. CONCLUSIONS: In this model, biphasic plasmatic catecholamine release appears to primarily explain the physiopathology of the hemodynamic response to brain death induction.

Animals↗
PubMed2000

Relative importance of flow versus pressure in splanchnic perfusion during cardiopulmonary bypass in rabbits.

BACKGROUND: Decreased gastrointestinal perfusion has been reported during cardiopulmonary bypass (CPB). Conflicting results have been published concerning thresholds of pressure and flow to avoid splanchnic ischemia during CPB. This study compared splanchnic perfusion during independent and randomized variations of CPB pump flow or arterial pressure. METHODS: Ten rabbits were studied during mild hypothermic (36 degrees C) nonpulsatile CPB using neonatal oxygenators. Simultaneous measurements of tissue blood flow in four different splanchnic areas (gastric, jejunum, ileum, and liver) were performed by laser Doppler flowmetry (LDF) before CPB (T0) and during a 4-step factorial experimental block design. Pressure and flow were alternatively high or low in random order. RESULTS: Laser Doppler flowmetry was significantly lower than pre-CPB value but was better preserved (analysis of covariance) in all organs, except liver, when CPB flow was high, whatever the pressure. Splanchnic LDF values in the low- versus high-flow groups expressed as perfusion unit were (mean +/- SD): stomach, 94+/-66 versus 137+/-75; jejunum, 118+/-78 versus 172+/-75; ileum, 95+/-72 versus 146+/-83; and liver, 79+/-72 versus 108+/-118. No significant difference of LDF was observed between the high- and low-pressure groups, whatever the flow, except for liver: stomach, 115+/-64 versus 117+/-83; jejunum, 141+/-80 versus 148+/-83; ileum, 127+/-87 versus 114+/-76; liver, 114+/-88 versus 73+/-70. CONCLUSION: Prevention of splanchnic ischemia during CPB should focus on preservation of high CPB blood flow rather than on high pressure.

Animals↗