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Biomedical subjects

A Lev

Publications and source records attributed to A Lev.

At least 55 records · Page 3Linked to original sources
PubMed1987

Heating rabbit joint by microwave applicator.

Heating the joint to high temperatures using a microwave device may inhibit metabolic activity of the synovial tissue and enable higher penetration of antiinflammatory drugs into the joint cavity. To measure the temperature distribution of local thermotherapy, the hind joints of eight rabbits were heated by a 915 MHz microwave power source, using a special applicator. Temperatures of 44.0 +/- 2.8C, 36.1 +/- 3.8C, 39.6 +/- 2.3C, and 35.2 +/- 1.5C were measured after heating in the joint cavity, cartilage, muscle, and skin, respectively. The only significant increase in the temperature was recorded in the heated joint cavity (p less than 0.01). This new microwave device can be a therapeutic tool in treating joint diseases because of its advantage of heating the target organ only, eg, synovium, while sparing the adjacent tissues.

Animals↗
PubMed1986

Histopathological observations in the canine prostate treated by local microwave hyperthermia.

A large series of repeated experiments were performed applying localized microwave hyperthermia to the prostate in dogs using a new water-cooled skirt-type antenna [1], operating at 915 MHz, as part of a new hyperthermia apparatus being developed for the treatment of the prostate in humans. The prostate gland of 20 male dogs was heated repeatedly under general anesthesia, at temperatures between 40 degrees C and 47 degrees C, and for different lengths of time up to 10 h. The prostate and other tissues were evaluated histopathologically following treatments. Invariably, all treatments by hyperthermia of the prostate caused a mononuclear inflammatory infiltration in the interstitium and polymorphonuclear infiltration in the glandular elements. Permanent tissue damage was found to be time-and temperature-dependent. Heating at 42.5 degrees C (+/- 0.5 degrees 5C) for up to 1.5 h was found to be harmless and could be safely repeated with our equipment. This study was part of a preclinical evaluation of a new antenna and apparatus.

Animals↗
PubMed1986

Hemofiltration in septic ARDS. The artificial kidney as an artificial endocrine lung.

Twenty-four patients with high microvascular permeability pulmonary edema were initially treated by means of conventional supportive therapy for 1-12 days. Continued deterioration was treated by predilutional hemofiltration and induced a dramatic improvement in 22/24 patients. Survival was 92%. Sieving coefficients for autacoids and middle molecular weight vasoactive peptides involved in the development of high microvascular permeability pulmonary edema were higher than 0.88 indicating that clearing from blood of these peptides during one pass through the hemofilter is similar to that obtained during one pass through the pulmonary normal microvasculature. Hemofiltration seems to be a significant breakthrough in the treatment of ARDS secondary to severe sepsis.

Acute Kidney Injury↗
PubMed1986

Further observations on the use of local hyperthermia for the treatment of diseases of the prostate in man.

Hyperthermia - the sustained controlled heating of tissues to 42-43 degrees C - is being studied and used as a means of treatment, particularly to selectively destroy malignant cells. This may be achieved by heat alone, or in conjunction with other forms of treatment, such as radiotherapy or chemotherapy, thanks to a synergistic effect obtained. A new microwave apparatus has been designed and developed which permits precise, controlled and safe hyperthermic treatment of the human prostate. Following extensive laboratory and experimental studies, a first series of treatments on humans has been carried out. Initial observations on our first 192 treatments, on 32 patients, are reported.

Chronic Disease↗
PubMed1985

[Non-cardiac pulmonary edema: an enigma today].

Pulmonary oedema is caused by an excessive accumulation of interstitial fluid in the lungs: in the case of left ventricular failure, oedema arises due to an increase in capillary hydrostatic pressure. Non-cardiac oedema, on the other hand, is brought about by a change in alveolar capillary membrane permeability. Although the causes are different, namely respiratory distress syndrome in adults, altitude-induced pulmonary oedema, oxygen toxicity, medication, metabolic changes, etc., the result is the same, i.e. damage to the alveolar capillary membrane. This damage appears to be brought about by two factors: complement activation and damage to the blood clotting mechanism. The difference between cardiac and non-cardiac pulmonary oedema is difficult to gauge. If pulmonary cone pressure is normal or low, and if the oedematous fluid/plasma protein ratio is greater than 0.7, the oedema is non-cardiac in origin. Treatment is carried out with the aim of repairing the alveolar capillary membrane and preventing extension of the damage. Respiratory insufficiency is treated by a mechanical respirator, applying positive pressure at the end of expiration. Fluid administration is adjusted according to pulmonary cone pressure levels. Opinions are still divided over whether to administer crystalline or colloidal solutions, steroids or protease inhibitors.

Adrenal Cortex Hormones↗
PubMed1985

[Non-cardiac pulmonary edema in a patient with recent cardiac pulmonary edema].

Pulmonary oedema may be cardiac or non-cardiac in origin: these two forms are clinically indistinguishable and their treatments are completely different. A case of pulmonary oedema is reported. This was believed to be of cardiac origin but did not respond to conventional treatment with diuretics and positive fibrotropic drugs. Insertion of a Swan-Ganz catheter revealed low capillary wedge on pressure. This, in turn, indicates that pulmonary oedema is non-cardiac in origin. The administration of liquids and cortisones led to a rapid improvement in the patient's condition. It is concluded that, whenever conventional treatment of pulmonary oedema fails, the possibility of non-cardiac oedema should be considered. In order to check this, capillary wedge pressure is measured.

Blood Gas Analysis↗
PubMed1985

Hemofiltration in severe septic adult respiratory distress syndrome associated with varicella.

One case of severe varicella pneumonia with high microvascular permeability pulmonary edema and signs of multiple system organ disfunction was successfully treated by means of hemofiltration. The patient was discharged from the Intensive Care Unit 6 days after admission. Peptides showing molecular weight ranging between 600 (prostaglandins) and 4000 (B-endorphin) daltons were cleared from blood at the same rate as urea. Hemofiltration appears to be a valuable tool for treating septic ARDS.

Adult↗
PubMed1985

Hemofiltration in severe high microvascular permeability pulmonary edema secondary to rickettsial spotted fever.

Two patients, affected by spotted fever, developed low pulmonary capillary wedge pressure (PCWP) pulmonary edema with severe hypoxemia. Conventional specific and supportive therapy, including mechanical ventilation, failed to induce significant respiratory and hemodynamic improvement which was dramatically reached by means of hemofiltration. Removal of circulating middle molecular weight peptides by the convective mass transfer, characteristic of hemofiltration, offers a new and effective therapeutic approach for the adult respiratory distress syndrome secondary to rickettsial diseases.

Adult↗
PubMed1984

Combined use of HFPPV with low-rate ventilation in traumatic respiratory insufficiency.

Two patients with chest injuries, flail chest and respiratory failure were mechanically ventilated by a system composed of 2 Bennett respirators and an independent source of gas. This system provides high-frequency positive pressure ventilation (HFPPV), low-frequency conventional mechanical ventilation (LFCMV) and high inspiratory flow of fresh gas (HIF), through the independent source. This system made use of the advantages of HFPPV and also solved the problem of possible CO2 retention. Using this system we could ventilate the patients while they were fully conscious and cooperative, thus eliminating the need for sedatives and muscle relaxants. Time of mechanical ventilation was shortened since the internal pneumatic fixation was very good and made it possible for the fractured ribs to unite rapidly. Restoration of spontaneous breathing was immediate after disconnection from the ventilator. We suggest this method as another mode of ventilation for patients with flail chest and respiratory failure.

Aged↗
PubMed1984

Sequential hemofiltration in nonoliguric high capillary permeability pulmonary edema of severe sepsis: preliminary report.

Five patients with nonoliguric adult respiratory distress syndrome (ARDS) secondary to severe sepsis showed improved blood oxygenation after up to 36 h of conventional therapy and mechanical ventilation with optimal positive end-expiratory pressure. However, metabolic acidosis was unchanged, and blood urea had increased. Some patients showed hemodynamic signs of incipient heart failure. After sequential hemofiltration, the altered physiologic shunt and blood pH returned to normal. Chest x-rays showed clearing of interstitial pulmonary edema. Patients recovered from ARDS in spite of fluid accumulation. Mechanical ventilation was stopped up to 8.5 h after the last hemofiltration. We postulate that convective ultrafiltration clears the blood of circulating low- and middle-weight vasoactive molecules implicated in the development of high microvascular permeability acute pulmonary edema secondary to sepsis.

Adult↗
PubMed1984

Freshwater near-drowning: our experience in life-supportive treatment.

Eight freshwater near-drowning victims were treated in the General Intensive Care Unit. The most prominent findings upon arrival were respiratory failure, hypoxemia and coma. Routine treatment, including mechanical ventilation and brain resuscitation, was initiated in all patients. Six patients were discharged fully recovered from the unit on the 3rd to 6th day; one patient who recovered fully but had amnesia was discharged after 8 months; and one patient remained decerebrated and died 5 months later. A more aggressive treatment of near-drowning victims is justified and recommended.

Adolescent↗
PubMed1983

Modification of the conformational equilibria in the sodium and potassium dependent adenosinetriphosphatase with glutaraldehyde.

Glutaraldehyde treatment of electroplax membrane preparations of Na,K-ATPase leads to irreversible changes in the enzymic behavior of the protein, which are not due to modification of the active site. When the glutaraldehyde treatment is carried out in a medium containing K+ and without Na+, the "K+-modified enzyme" so produced shows the following changes in enzymic properties: The steady-state phosphorylation by ATP and the rate of ATP-ADP exchange are decreased to approximately 40% of control, while Na,K-ATPase activity decreases to approximately 15% of control. Phosphatase activity is decreased very little, but the potassium activation parameters of the reaction are changed, from K0.5 approximately equal to 5 mM and nH = 1.9 in control to K0.5 approximately equal to 0.5 mM and nH = 1 in K+-modified enzyme. KI(app) for nucleotide inhibition of phosphatase activity is increased significantly. Changes in the cation dependence of the ATPase reaction are also observed. All of these effects can be explained by assuming that the cross-linking of surface groups in protein subunits when they are in conformation E2 shifts the intrinsic conformational equilibrium of the enzyme toward E2. We considered the simplest mathematical model for the coupling between K+ binding and the conformational equilibrium, with equivalent potassium sites that must be simultaneously in the same state. If one assumes that the potassium activation of phosphatase activity in the K+-modified enzyme reflects the affinity for K+ of E2, the behavior of the phosphatase activity in the native enzyme can be fit if there are only two potassium sites, whose affinity is 80-fold higher in E2 than in E1, and the equilibrium constant for E2 in equilibrium E1 is about 250. The same sites can explain the activation of dephosphorylation during ATP hydrolysis. Independent of the model chosen, potassium ions must be required for the catalytic action of form E2 and cannot be merely "allosteric activators". The enzyme modified with glutaraldehyde in a medium containing Na+ also has interesting properties, but their rationalization is less straightforward. The Na,K-ATPase activity is inhibited more than the "partial reactions", as in the K+-modified enzyme. We suggest that this is a generally expected result of modifications of the enzyme.

Aldehydes↗
PubMed1983

Synchronized intermittent mandatory insufflation of the endotracheal tube cuff.

Continuous inflation of endotracheal tube cuffs causes tracheal injury in up to 11% of intubated patients. To avoid this complication and its consequences of tracheal and laryngeal stenosis and tracheoesophageal fistula, we designed a simple device which enables intermittent inflation of the cuff during inspiratory periods of mechanical ventilation. This was achieved by connecting the inlet of the cuff of the pressure regulating tubing of the expiratory valve of a Bennett respirator. We have used the device in 25 patients with prolonged intubation. There was no air leak around the tube, no aspiration of gastric content, and no late complications as shown by direct laryngoscopy at 1 week, 1 month, and 3 months after extubation, and by X-ray of the upper airway.

Adolescent↗
PubMed1983

The use of conventional ventilators for high frequency positive pressure ventilation.

Ten randomly selected patients were ventilated for defined periods with 2 ventilatory modes: (a) high frequency positive pressure ventilation (HFPPV) (frequency 66-70 min; tidal volume 1-3 ml/kg body weight), (b) conventional IPPV (frequency 16/min; tidal volume (VT) 10-15 ml/kg). This was done successfully using conventional ventilators, and keeping other variables (FIO2, PEEP) constant. Various ventilatory and hemodynamic variables were measured and compared during both modes of ventilation. The most prominent finding was a considerable reduction of cardiac output (CO) and stroke volume (SV) during intermittent positive pressure ventilation (IPPV) compared with HFPPV. Peak tracheal pressure was significantly lower during HFPPV. An increase in mean systemic arterial pressure and in oxygen transport was observed during HFPPV, whereas transpulmonary shunt and pulmonary vascular resistance (PVR) decreased during HFPPV. These findings are in accordance with previously reported advantages of HFPPV, and might be of importance in the treatment of patients with bronchopleural fistula, adult respiratory distress syndrome (ARDS), left ventricular failure and other conditions in which conventional positive pressure ventilation (PPV) fails.

Adult↗