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Biomedical subjects

J P Lançon

Publications and source records attributed to J P Lançon.

At least 19 recordsLinked to original sources
PubMed1995

Inhaled cigarette smoke selectively reverses human hypoxic vasoconstriction.

The acute effects of the inhaled gas phase of cigarette smoke on pulmonary (PAP) and systemic (SAP) arterial pressures and on plasma arterial cGMP content were compared with those of inhaling 10, 20 and 80 ppm nitric oxide (NO) in one healthy adult volunteer spontaneously breathing a hypoxic gas mixture. Hypoxia (FIO2 0.12) induced a sustained, stable pulmonary vasoconstriction. Inhaled NO induced a dose-dependent fall in PAP; plasma cGMP rose from 39.4 (hypoxia) to 164 pmol/ml (hypoxia plus 80 ppm NO). Exposure to cigarette smoke induced a rapid, consistent and reversible fall in PAP; plasma cGMP rose from 45.5 (hypoxia) to 138 pmol/ml (hypoxia plus cigarette smoke). Neither NO nor cigarette smoke inhalation induced any change in SAP. These data suggest that exposure to cigarette smoke is able selectively to reverse acute hypoxic vasoconstriction in humans without causing systemic vasodilation, an effect likely mediated through the NO-cGMP pathway.

Administration, Inhalation↗
PubMed1994

[Do halogenated anesthetics protect from ischemic and reperfusion myocardial injuries?].

Ischaemia and reperfusion of the myocardium are associated with cellular injuries leading to a decrease of contractile function and the occurrence of arrhythmias. As reperfusion of an ischaemic heart results in an intracellular overload of calcium, a calcium blocking agent pretreatment has been shown to exert a protective effect. By altering myocardial calcium fluxes, volatile anesthetics might also protect the myocardium from ischaemic damage and reperfusion injuries. A beneficial effect of volatile anesthetics on the ischaemic myocardium has been shown in numerous studies. These agents decrease the severity of ischaemia as well as the incidence of reperfusion arrhythmias and improve recovery of myocardial mechanics during reperfusion. They also preserve myocardial energetics and protect from oxygen-derived free radicals injury. However, some studies do not support these protective effects. The wide discrepancy between the various protocols might explain the discrepancy of the results. Enflurane and halothane seem to be more efficient than isoflurane. This cannot only be explained by different cardiovascular effects, but also by a specific effect on myocardial cells. Halothane and enflurane mainly decrease intracellular calcium availability by a direct effect on sarcoplasmic reticulum, while isoflurane only decreases the transsarcolemnal calcium entry. Enflurane and halothane have more beneficial effects than isoflurane on free radicals induced myocardial injuries. In conclusion, despite a wide diversity between the different studies, halothane and enflurane have better protective properties against ischaemia and reperfusion myocardial injuries than isoflurane.

Animals↗
PubMed1994

Effects of atrial pacing on right ventricular contractility after coronary artery surgery.

Increasing heart rate enhances the strength of contraction of cardiac fibers. This has been demonstrated in vitro and recently for the left ventricle. To study this phenomenon on the right ventricle, the effects of increasing heart rate by atrial pacing on right ventricular (RV) contractility were observed after coronary artery surgery in 20 patients. Right ventricular ejection fraction (EF) and stroke volume (SV) were measured by use of a rapid-response thermistor pulmonary artery catheter. Right ventricular volumes were calculated from EF and SV. Right ventricular contractility was assessed by the slope of the end-systolic pressure-volume relationship (ESPVR) before and after increasing RV preload by means of military antishock trousers (MAST) inflation. The dP/dtmax/end-diastolic volume index (EDVI) ratio, which is independent of ventricular preload, was also used as an inotropic index. Results are expressed as mean +/- SEM. Right ventricular preload, as reflected by RVEDVI, was increased by MAST inflation (99 +/- 6 mL/m2 v 106 +/- 7 mL/m2, P < 0.01), but returned to control values when inflation of MAST was combined with pacing (100 +/- 6 mL/m2). The slope of the RV ESPVR significantly increased when heart rate was increased (0.22 +/- 0.03 mmHg/mL/m2 before pacing v 0.77 +/- 0.07 mmHg/mL/m2 during pacing, P < 0.05). The dP/dtmax/EDVI ratio was also increased by pacing (2.32 +/- 0.4 mmHg/min/mL/m2 before pacing v 3.15 +/- 0.5 mmHg/min/mL/m2 during pacing, P < 0.01). Moreover, cardiac index was increased by pacing alone (2.45 +/- 0.2 L/min/m2 v 2.78 +/- 0.2 L/min/m2, P < 0.01), and significantly more when MAST were inflated (2.94 +/- 0.2 mL/m2, P < 0.05 v pacing alone). It is concluded that increasing heart rate by atrial pacing increases RV inotropic status after coronary artery surgery.

Adult↗
PubMed1992

[Value of biological tests in the early diagnosis of acute steatosis in pregnancy].

Four cases of acute fatty liver of pregnancy occurring over a ten year period are reported. All four patients had a caesarean section and one died postoperatively. The seven children (three twin pregnancies) were all alive. The early clinical signs were unspecific. Jaundice was the only one occurring in all patients. Routine biological tests before the jaundice develops may be of help for a diagnosis early enough to start the treatment in patients with unspecific gastrointestinal or hepatic manifestations, especially the liver function and blood coagulation tests. These latter allow to discord the diagnosis of viral hepatitis and the "Haemolysis-Elevated Liver enzyme concentrations-Low Platelets" (HELLP syndrome) respectively. Indeed, only a liver biopsy can ascertain the diagnosis.

Adult↗
PubMed1992

[Preoperative evaluation of respiratory function in thoracic surgery. Do reliable predictive criteria exist in that type of surgery?].

A cautions analysis of the respiratory preoperative study may decrease morbidity and mortality after pulmonary surgery. To search for predictive criteria of respiratory complications following this kind of surgery, 454 patients have been studied retrospectively. Morbidity was defined as the need for postoperative ventilation. Preoperative criteria were divided in clinical (age, obesity, history of pulmonary disease, dyspnea, score of Karnofsky), laboratory (blood gases, spirometry) and surgical (kind of procedure). Three criteria were significant for morbidity (15 ventilated patients) and mortality (27 deaths): age (> 65 years), obesity, hypocapnia (pCO2 < 4.1 kPa-31 mmHg). Analysed spirometric values were no significant.

Age Factors↗
PubMed1992

[Hemodynamic complications during the recovery period after anesthesia].

In the postoperative period the alterations of blood pressure are the main hemodynamic complications. Hypotension or hypertension may compromise the coronary circulation and increase the metabolic demand of the myocardium. Pulmonary oedema is the most frequent manifestation of heart failure. The aim of its treatment is to increase myocardial contractility and decrease the metabolic demand. Myocardial ischemia is mostly silent and is an important correlate of adverse cardiac outcomes. The treatment of these hemodynamic events starts during the peroperative period by prevention of their risk factors.

Anesthesia Recovery Period↗
PubMed1992

[Post-traumatic aortic valve insufficiencies].

Aortic regurgitation due to closed chest trauma is rare. It is related either to a valve lesion itself (ruptured cusp) or to trauma of the ascending aorta (subadventitial rupture with prolapse of the underlying aortic valve cusp). Four cases are described, 2 men and 2 women aged 30 to 66 years, after severe injuries in road traffic accidents: three patients had rupture of the aorta and the other had isolated rupture of the non-coronary aortic valve cusp. This pathology is unique due to the pathogenic mechanism associated with multiple thoracic injuries (right costal flap, sternal fracture, pulmonary contusion ...). The polytraumatic context explains the diagnostic difficulties and the secondary importance of the valve problem. Late surgery of these lesions was conservative in 3 cases: valve replacement was necessary in 1 case. If the haemodynamic tolerance of the aortic regurgitation is good, surgery should be deferred until the polytraumatic emergency has been dealt with. Good surgical results, often with conservative procedures, encourage earl operation after the acute polytraumatic period.

Adult↗
PubMed1991

Blood salvage in cardiac surgery.

The aim of this study was to evaluate blood salvage provided by an intraoperative blood recovery system (IBRS) and a mediastinal drainage blood recovery system (MBRS) during and after cardiac surgery. Sixty-six patients undergoing aortocoronary bypass surgery were randomly assigned to three groups of 22 patients each. In group I, patients received only homologous blood (HB). Group II and group III patients received the blood content of the oxygenator after concentration by an IBRS at the end of the operation. In group III, patients also received their own mediastinal drainage blood, shed for 6 hours after operation, after concentration and washing in a MBRS. The patients were transfused with homologous blood if needed, in order to obtain a hematocrit of 28% at the end of operation, 30% the following day, and a hemoglobin level over 10 g/dL while on the cardiac surgery ward (8 to 10 days). The three groups were comparable with respect to age, body surface, preoperative and postoperative hematocrits, number of grafts, bypass duration, and postoperative mediastinal blood loss. The amount of HB that was transfused during the operation was significantly lower in groups II and III than in group I (P less than 0.0001). After the operation it was significantly lower in group II than in group I (P less than 0.05), and in group III versus group I. Thus, 13.6% of patients in group II and 38% of patients in group III did not require HB transfusion. No infection, renal dysfunction, or coagulation disorders were observed. It is concluded that the use of an IBRS allows a significant saving of HB. However, because it does not avoid all HB requirements, it should be associated with other techniques to avoid blood transfusion such as the MBRS or predonation.

Aged↗
PubMed1991

[A radiologic image to be recognized in patients with thoracic injury: the retroligamentary pneumatocele].

A 17-year-old female patient had a road traffic accident. She suffered from a minor head injury, and a right pneumothorax which had to be drained. However, when admitted, an unusual picture was found on the chest film. It was a left para-mediastinal shadow with a fluid level, its greater axis being vertical. She underwent a computerised tomographic chest scan. This picture was seen to be in the left costo-vertebral gutter, and in contact with an area of pulmonary contusion in the left posterior basal segment. Another smaller similar picture was discovered on the right side. These were interpreted as being infrapleural pneumatoceles on the mediastinal surface of the lower pulmonary lobes. The patient recovered spontaneously. In fact, these effusions of air and blood can be seen in other areas in the chest (mediastinum, pleura, lung); these are discussed.

Adolescent↗
PubMed1991

[Amikacin concentrations in lung and serum after single intratracheal administration in men].

This study was designed to assess the diffusion into lung tissue and systemic circulation of amikacin administered endotracheally. Eleven consecutive patients, suffering from lung carcinoma and scheduled for elective pneumonectomy or lobectomy, were included in the study. After induction of anaesthesia and before tracheal intubation, a single 500 mg amikacin dose was administered endotracheally through a catheter whose tip was located 5 cm below the vocal cords. Blood was then collected every 15 min for serum assays, until pulmonary resection had been carried out. Pulmonary concentrations were assessed in a healthy area. Measurements were carried out in duplicate using fluorescence polarizing immunoassay and microbiological methods. Serum peak concentrations were found 105 min after administration (7.97 +/- 5.62 micrograms.ml-1). Six and 12 h after administration, serum concentrations were 3.19 +/- 1.87 and 1.20 +/- 0.67 micrograms.ml-1 respectively. Mean lung concentrations were 1.85 +/- 2.12 micrograms.g-1, with a corresponding serum level of 7.22 +/- 4.36 micrograms.ml-1. However, endotracheal instillation of amikacin provided serum concentrations which, were not high enough for treatment of gram negative pneumonia. Lung concentrations are lower than both serum levels and MIC90 for gram negative bacilli. Moreover, there was a major heterogeneity in serum and lung levels, which seemed to be unpredictable. This was probably due to heterogenous tracheal, bronchial and alveolar absorption. The results obtained in this study with a single dose administration should be reassessed in the light of data obtained with long-term amikacin administration.

Administration, Inhalation↗
PubMed1991

Cardiac beta-adrenergic receptor density measured in vivo using PET, CGP 12177, and a new graphical method.

The in vivo quantification of myocardial beta-adrenergic receptor has been obtained in five closed-chest dogs using positron emission tomography (PET). The ligand was racemic (+/-)[11C] CGP 12177, a very potent hydrophilic antagonist of the beta-adrenergic receptor. A kinetic method appeared unsuitable because of the presence of metabolites which made the input function difficult to measure and also inaccurate. Therefore, a graphical method, based on a particular protocol, was proposed. The animals were injected with a trace amount of (+/-)[11C]CGP 12177, which was followed 40 min later by a second injection of radioligand with a low-specific activity. An additional injection of an excess of unlabeled CGP 12177 was administered after 90 min and allowed for the estimation of the dissociation rate constant. The main advantage of this graphical approach is that the results are obtained without having to measure the input function and therefore without estimating the metabolites. The average value of Bmax was 31 +/- 4 pmole/ml of tissue and the dissociation constant was 0.014 +/- 0.002 min-1.

Adrenergic beta-Antagonists↗
PubMed1991

[Hemodynamic effects of milrinone in the treatment of cardiac insufficiency after heart surgery with extracorporeal circulation].

Milrinone is an inotropic agent of the phosphodiesterase inhibitor family. In common with all molecules of this class it has both positive inotropic and vasodilator effects. The haemodynamic effects of 3 dosages of milrinone were studied in 25 patients with low output states after open heart surgery. The low cardiac output was defined as a cardiac index of less than 2.5/min/m2 and pulmonary capillary pressures greater than 8 mmHg. Milrinone was administered as a bolus of 50 micrograms/kg/min over 10 minutes followed by a continuous infusion for at least 12 hours. Six patients were given 0.375 micrograms/kg/min, six patients 0.5 micrograms/kg/min, and 13 patients 0.75 g/kg/min. A significant increase in cardiac index was observed but without any difference between the 3 groups. The heart rate and stroke volumes were increased. There was a mild reduction in systemic blood pressure with a decrease in systemic arterial resistances which returned to almost normal values. Left and right filling pressures did not decrease significantly from the initial values until the end of the bolus injection. Indirect measurements of myocardial oxygen consumption showed an increase in this parameter. There were no changes in blood gas concentrations. The treatment was stopped in only one patient because of peripheral vasodilation. Two patients developed supraventricular tachycardia of no consequence. Milrinone may therefore be proposed as treatment of first intention of low cardiac output states after open heart surgery. It is associated with a mild vasodilatory effect. Improved myocardial function is observed providing attention is paid to vascular filling. None of the maintenance doses used after the bolus injection was shown to be more effective than the others.

Aged↗
PubMed1991

[Treatment of cardiogenic shock with exclusion of inotropic drugs].

Cardiogenic shock comprises peripheral hypoperfusion and pulmonary vascular overload. The goals of therapy are to reduce pulmonary congestion by lowering pulmonary capillary wedge pressure and to increase cardiac index. Volume loading is the first step of treatment. It helps to place the patient on the Franck-Starling relationship. This challenge studies the effects of an increased preload on stroke volume. It has to be done even in case of major heart failure. The main effect of venous vasodilators is to decrease myocardial oxygen consumption. Arteriolar vasodilators also decrease left ventricular end systolic volume. Fluid overload may be treated by diuretics or by extra renal devices: peritoneal dialysis or hemofiltration. Intractable cardiogenic shock may respond to cardiac assist devices (intra aortic balloon pump, pump assistance) as a bridge to surgery.

Counterpulsation↗
PubMed1991

[Anesthesia, intensive care for emergency surgery of the thoracic aorta. A retrospective study over 10 years].

Fifty eight patients underwent emergency thoracic aortic surgery over a nine year period (Nov 80 Nov 89). Two pathologies may be opposed with regard to etiology, circumstances and patients. Traumatic aortic ruptures (18): the most common location of the tear was at the isthmus of aorta (18). They occurred in a violent crash and often affected young patients. Early treatment gave a good prognosis, outcome depending on other lesions. Others (40) were descending aortic aneurismal fissure, ascending aortic dissection and compound type B dissection (ischemic form or breaking point). These affected an older population with an important cardio-vascular risk. This high risk population combined with an open chest surgery with or without extracorporeal circulation aggravated the prognosis.

Adolescent↗
PubMed1990

[Changes in myocardial metabolism induced by drugs used during intensive care].

More and more patients with coronary heart disease (CAD) are admitted to intensive care units. The drugs used to treat these patients have various effects on the myocardium which must be known in order to avoid worsening the CAD. This review examines the metabolic effects on the myocardium of the most commonly used drugs in intensive care. The physiology of myocardial oxygen supply is first recalled with regard to the coronary circulation, myocardial oxygen extraction and consumption. Digitalis glycosides do not affect the coronary circulation, but the decrease myocardial oxygen consumption in patients with heart failure, mainly by lowering heart rate. Dihydropyridine calcium blockers (nifedipine, nicardipine) increase coronary blood flow, despite a decrease in arterial blood pressure. Their effects on myocardial oxygen consumption are mediated by a sympathetic reflex. Verapamil decreases the heart rate and myocardial inotropism, and is responsible for coronary vasodilation. The result is a decrease in myocardial oxygen consumption. Diltiazem and bepridil have almost similar effects: they decrease myocardial oxygen consumption and increase blood supply to the heart. It has been recently shown that verapamil was the most depressant calcium channel blocking agent, and that it resulted in the most important decrease in myocardial metabolism. Beta-blocking agents decrease myocardial metabolism, except those with an important intrinsic sympathomimetic activity, such as pindolol. Amiodarone can be considered as an alpha and beta blocking drug: its main effect is to counteract the effects of endogenous catecholamines on myocardial metabolism. The sympathomimetic amines (noradrenaline, adrenaline, isoprenaline, dopamine, dobutamine) increase, to different extents, myocardial oxygen consumption. Vasodilators, such as the nitrates or sodium nitroprusside, decrease cardiac filling pressures, and increase myocardial blood flow, thus lowering myocardial oxygen consumption. Phosphodiesterase inhibitors (amrinone, enoximone) have both an inotropic and a vasodilating effect. They decrease cardiac afterload, and increase blood supply to the myocardium; this compensates for the increase in myocardial oxygen consumption due to the increase in myocardial contractility. Because all the drugs used in intensive care have different effects on myocardial metabolism, their reasoned use should avoid an inappropriate increase in oxygen demand.

Adrenergic beta-Antagonists↗
PubMed1990

[Comparison of enoximone versus tobutamine in the treatment of low cardiac output after cardiac surgery].

Enoximone, a new cardiotonic agent not related to glycosides or catecholamines, has been suggested for treatment of low cardiac output syndromes occurring after cardiopulmonary bypass (CPB). The aim of the present study was to compare enoximone with dobutamine in the management of such cases. Twenty consecutive patients who had undergone cardiac surgery with CPB and who had a cardiac index (CI) less than 2.5 l.min-1.m-2, pulmonary capillary wedge pressure greater than 12 mmHg, and no renal failure, were randomly assigned to receive either enoximone (group E, n = 10) or dobutamine (group D, n = 10). The following parameters were monitored at baseline, 15, 30, 60, 90 min, 2, 6, 10 and 14 h: arterial, central venous, pulmonary arterial and capillary wedge pressures (PCWP), cardiac index (CI), stroke volume index (SVI), stroke work index (SWI), systemic (SVR) and pulmonary vascular resistances, as well as heart rate-pressure product (HRPP). Patients in group E were given a bolus of 0.5-1 mg.kg-1 enoximone over a 20 min period, followed by a continuous infusion of 2-20 micrograms.kg-1.min-1, depending on clinical response. In group D, patients were given 2.5 to 15 micrograms.kg-1.min-1 dobutamine according to clinical response. No other inotropic drug was used during the study period. The aim was to obtain an increase in CI greater than or equal to 30% at the end of the first hour of treatment. Excessive systemic hypotension with low SVR was treated with volume loading.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗