Biomedical subjects
C Perret
Publications and source records attributed to C Perret.
[Acquired immunologic deficiency syndrome, opportunistic infections and homosexuality. Presentation of 3 cases studied in Switzerland].
Three cases of multiple opportunistic infections in previously healthy homosexual males were observed in 3 different University Hospitals in Switzerland. Two of the patients died. Infections were multiple, with P. carinii pneumonia (3 cases), chronic mucocutaneous ulcers probably due to Herpes simplex virus (2 cases), mucosal candidiasis (2 cases) and disseminated infections due to cytomegalovirus (1 case) and Mycobacterium avium (1 case). All patients had depressed cellular immunity with marked lymphopenia. These cases are similar to those recently observed in the United States, but two of the patients had never been to the USA although both had vacationed in Haïti where the syndrome has been described. These patients illustrate that this new syndrome should also be suspected outside the USA when a patient (especially a male homosexual) presents with persistent fever of unknown origin and develops opportunistic infections without obvious underlying disease.
[Massive poisoning with cyanide with favorable outcome. Hemodynamic study].
A 60-year-old chemist was admitted two hours after voluntary intake of 600 mg KCL. Upon admission he was in deep coma and bradypneic but non-cyanotic. Arterial blood gas analysis showed severe lactic acidosis; blood cyanide concentration was well above the lethal level. The patient was intubated and artificially ventilated with highly hyperoxic mixtures. Specific treatment included sodium nitrite and sodium thiosulfate. The patient recovered without sequelae despite excessive methemoglobinemia. The hemodynamic study upon admission showed a hyperdynamic status associated with low peripheral resistances and normal filling pressures, a profile similar to that described in response to acute anoxia in experimental animals.
[Prognosis of acute psychotropic drug poisoning. The Lausanne experience].
366 charts are reviewed of patients admitted to the ICU of the Lausanne University Department of Medicine during 5 consecutive years for psychotropic drug overdose and treated by supportive management. 25% were severely intoxicated and 46 patients required ventilatory support either for aspiration pneumonia or CNS depression. The mortality rate was 0.5% and mean stay in the ICU 2.8 days. Neither the two deaths nor the complications (already established upon admission or within 6 hours of presentation) could have been prevented by hemoperfusion. The efficiency of conservative management raises questions about the value of extrarenal clearance technics in the absence of concurrent renal failure.
In situ demonstration of T cells in alopecia areata.
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Variable hemodynamic response to sodium nitroprusside in hypertensive crisis.
Five patients, three males and two females, admitted with severe hypertensive crisis underwent hemodynamic investigations before and during vasodilator therapy with sodium nitroprusside. In three hypervolemic patients with congestive heart failure and/or renal insufficiency, the drug induced a rapid fall in systemic arterial pressure and a beneficial effect on cardiac performance, as shown by a shift of the ventricular function curves to the left. In two hypovolemic patients, the hemodynamic response was quite different; vasodilator therapy induced a confusing clinical picture characterized by significant fluctuations in blood pressure, a severe fall in cardiac output and clinical signs of shock in spite of normal blood pressure. Hemodynamic response to vasodilator therapy with sodium nitroprusside in hypertensive crisis appears to be directly related to the circulating blood volume. The syndrome of hypertension associated with hypovolemia needs to be recognized promptly in order to avoid inappropriate therapy; in such cases volume expansion under precise hemodynamic monitoring appears to be an effective means of stabilizing the cardiocirculatory conditions.
The PIOTRON: initial performance, preparation and experience with pion therapy.
The PIOTRON is a large solid angle superconducting channel built for the use of negative pi-mesons in radiotherapy. The pions are produced by protons of 590 MeV striking a target of molybdenum or beryllium. The pions are divided into 60 channels and deflected twice to enter the treatment volume radially. The momentum and the momentum band for all 60 channels can be chosen and the beam spot of Bragg peak pions at the isocenter of the applicator is a few centimeters in each direction. Dynamic scanning can thus achieve 3-dimensionally shaped treatment volumes. Two different methods are available: the ring scan, using changes of pion range; and the spot scan, involving translation of the patient through the fixed beam spot. Dose distributions of individual and multiple beams were plotted in a cylindrical water phantom. Radiobiological experiments with mammalian cells in gel and with mouse feet were performed. A special beam geometry using a sector of 15 beams was selected for the first treatments of patients with metastatic skin nodules. Six patients were treated. Acute skin reactions were scored and compared with those from orthovoltage therapy with comparable beam geometry. The RBE for 10 fractions is between 1.4 and 1.5. The next step involved treatment of patients inside water-bolus rings in preparation for dynamic therapy. Patients were then treated with the spot scan dynamic mode in the water bolus. The initial responses and reactions are favorable and confirm the feasibility and accuracy of dynamic pion therapy.
[Myocardial dysfunction in septic shock].
Septic shock is known to induce progressive myocardial dysfunction characterized hemodynamically by a decrease in cardiac output and a rise in ventricular filling pressures. Both ventricles are affected. Benefit from inotropic agents is inconsistent. Identification of the factors responsible for the progressive cardiac deterioration is rendered difficult by the complexity of clinical situations. Experimental models demonstrate a progressive inhibition of contractility. Several arguments suggest the possible role of interstitial myocardial edema in altering the microcirculation, decreasing substrate delivery and diminishing ventricular compliance. The role of a myocardial depressant factor has still to be demonstrated.
Entrainment of the spinal pattern generators for swimming by mechano-sensitive elements in the lamprey spinal cord in vitro.
Imposed sinusoidal bending of a mobile region of the curarized spinal cord/notochord preparation of the lamprey results in phase-locking (i.e. 'entrainment') of the 'fictive swimming' motor pattern (recording in ventral roots) to the bending movements. This entrainment phenomenon occurs both with intact ventral and dorsal roots and with all roots cut (i.e. a completely isolated spinal cord). It is proposed that mechano-sensitive elements within the spinal cord contribute in part to the entrainment.
[Physiopathology and treatment of cardiac insufficiency in the acute stage of infarct].
Pump failure in acute myocardial infarction is a frequent complication in which the prognosis is still uncertain. The effects of ischemia and necrosis on ventricular performance are discussed, more specifically with reference to the role of some adaptive processes in exacerbating cardiac failure or lesion extension. The different therapeutic approaches considered have a dual purpose: to improve ventricular performance but without aggravating myocardial O2 balance. The hemodynamic response to a decrease in afterload and/or preload obtained by vasodilators is compared to the effects of beta-adrenergic agents. A therapeutic scheme is proposed.
[Mechanical ventilation in the treatment of acute respiratory insufficiency in asthma].
The purpose of this study was to evaluate the results of mechanical ventilation in life-threatening status asthmaticus. 16 patients were treated for a total of 22 episodes of acute respiratory acidosis, with coma in 11 cases. Controlled mechanical ventilation was maintained from 10 to 196 hours and involved only minor complications without sequelae. All patients survived. These favourable results are attributed to a new strategy: the aim of mechanical ventilation is to relieve hypoxemia with hyperoxic mixtures without seeking rapid correction of hypercapnia, which is obtained later when bronchial desobstruction provides better conditions of VA/Q distribution. This allows low tidal volumes and low frequency, avoids high airway pressures and so decreases the danger of barotrauma and cardio-circulatory complications.
Efferent activity during fictitious scratch reflex in the cat.
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Oxygen delivery in acute exacerbation of chronic obstructive pulmonary disease. Effects of controlled oxygen therapy.
The hemodynamic response to controlled oxygen administration was investigated in 35 patients who presented with acute decompensation of chronic obstructive pulmonary disease. Gasometric and hemodynamic data were successively measured under inspiratory fractions in oxygen of 0.21 (room air) and 0.28. Response to oxygen therapy was characterized by a decrease in cardiac output and an increase in oxygen delivery because of a sharp increase in arterial oxygen content. The coefficient of oxygen delivery (oxygen delivery/oxygen consumption) increased in each patient. All these changes were highly significant (p les than 0.001). Somewhat unexpectedly, there was no change in pulmonary artery pressures, so that pulmonary arteriolar resistance even increased (p less than 0.05). Further analysis individualized 2 types of hemodynamic response to oxygen therapy. In 15 patients who presented with severe hypoxemia, oxygen therapy resulted in a significant increase in oxygen delivery without change in cardiac output. By contrast, in 20 patients with moderate hypoxemia, oxygen therapy induced a significant decrease in cardiac output (p less than 0.001) without change in oxygen delivery. Patients in whom cardiac output was unaffected by oxygen administration presented with a lower mixed venous oxygen tension (less than 35 mmHg) and a lower coefficient of oxygen delivery (less than 3.5). This study demonstrated that oxygen therapy does not always increase oxygen delivery in acute decompensation of chronic obstructive pulmonary disease.
[Treatment of decompression accidents and the current state of hyperbaric medicine].
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Respiratory response to acute metabolic acidosis.
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Activity of neurons of cerebellar nuclei during fictitious scratch reflex in the cat. II. Interpositus and lateral nuclei.
The activity of neurons of the interpositus and lateral cerebellar nuclei was recorded during fictitious scratch reflex in thalamic cats immobilized with Flaxedil. Interpositus neurons were identified by antidromic response to stimulation of the contralateral red nucleus. The interpositus neurons responding to passive movements of the ipsilateral hindlimb manifested rhythmical modulation of the discharge in relation with the scratch cycle. The neurons generated bursts of impulses separated by periods of silence. Different neurons were active in different parts of the scratch cycle, but most of them were active in the second half of the flexor phase. When the scratch reflex was evoked on the contralateral side, rhythmical modulation was observed in about half of the neurons, and it was less pronounced than in the case of ipsilateral scratching. Rhythmical modulation of cerebellar neurons during fictitious scratching is determined by signals coming from the central spinal mechanism, generating rhythmical oscillations, via the ventral spinocerebellar tract (VSCT) and the spinoreticulocerebellar pathway (SRCP). Results of separate transections of these pathways showed that the VSCT plays the crucial role in modulating interpositus neurons. Neurons of the lateral nucleus exhibited no modulation during fictitious scratching.
[Hemodynamic investigation, a logical approach to the treatment of acute myocardial infarction].
The prognostic and therapeutic significance of different haemodynamic variables and subsets in acute myocardial infarction are analyzed. Eighty-eight patients underwent bedside catheterization by the Swan-Ganz technique. They were subdivided into 4 groups according to initial mean pulmonary wedge pressure (PWP) and cardiac index (CI). In group I (PWP less than 18 mm Hg; CI greater than 2.21/min/m2) in-hospital mortality was 2%, in group II (PWP less than 18 mm Hg; CI less than 2.21/min/m2), 8%; in group III (PWP greater than 18mm Hg; CI greater than 2.21/min/m2), 25% and in group IV (PWP greater than 18 mm Hg; CI less than 2.21/min/m2), 67%. Group I corresponds to minimal or mild ventricular dysfunction and group IV to severe ventricular failure or shock. In group III, despite a higher CI, mortality was three times that observed in group II, which suggests that in the absence of clinical signs of hypoperfusion and shock a subnormal cardiac index is not detrimental provided it is not accompanied by tachycardia and increased left ventricular end-diastolic pressure. The hemodynamic patterns of acute myocardial infarction are very variable. Bedside monitoring to evaluate short-term prognosis and form a logical approach to medical therapy represents a major advance in coronary care. The mechanical consequences of acute necrosis may be promptly and often effectively treated, the final goal being the preservation of ischemic myocardium.
Main characteristics of the hindlimb locomotor cycle in the decorticate cat with special reference to bifunctional muscles.
In acute decorticate (thalamic) cats, efferent activities to various hindlimb muscles during the locomotor cycle were studied, using several complementary methods: muscle and motor nerve recordings, monosynaptic testing, intracellular recording from motoneurones, recording of fusimotor actions on single Ia afferents. The limb was fixed and peripheral influences could be either increased by exteroceptive stimulations or decreased by curarization and/or deafferentation. Our main results were the following: in all studied muscles, there is an alpha-gamma coactivation; there are pure flexor and pure extensor muscles with simple alternating activities; bifunctional pluriarticular muscles show complex activations which allow the division of the locomotor cycle into a flexion, an extension and two transition phases; alpha motoneurones of these muscles receive both flexor and extensor commands; the relative importance of the corresponding excitations depends on interactions between these central commands and peripheral inflow, especially through afferents acting according to the flexor reflex pattern. Based on these results, an attempt is made to explain how the complex and variable efferent activity can arise from an initially simple rhythmic command and produce the biomechanically adapted locomotor movement of the hindlimb.