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Biomedical subjects

F J Belda

Publications and source records attributed to F J Belda.

At least 37 records · Page 2Linked to original sources
PubMed1997

[The use of high-frequency jet ventilation for ventilatory support in an extreme case].

We report the case of a 27-year old man given a left lateral thoracotomy for emergency repair of the aortic isthmus, which had partially ruptured as a consequence of chest trauma. The patient also suffered serious trauma to the right lung, such that selective ventilation of that lung had to be applied with the left lung collapsed to allow the surgeon access to the descending aorta. Rapid decrease in SpO2 occurred, with excessively high airway pressures, requiring reinstatement of conventional ventilation of both lungs and interruption of surgery. Conventional ventilation was then replaced by high frequency jet ventilation to both lungs. That technique, combined with intermittent inflation of the left lung (inclined), provided sufficient oxygen as well as a wide and sufficiently immobile surgical field.

Adult↗
PubMed1996

Evaluation of the disinfectant effect of Solprogel against human immunodeficiency virus type 1 (HIV-1).

The antiviral activities of sodium dichloroisocyanurate (NaDCC) and a commercial product (Solprogel 2%) against human immunodeficiency virus type 1 (HIV-1) were investigated using a quantitative suspension test method. Solprogel is a compound that contains NaDCC and a biodegradable polymer of acrylic acid. Viral suspensions were prepared containing 3.2 x 10(6) tissue culture infective dose 50 (TCID50) in culture media. Syncytium formation in the MT-2 line and HIV antigen p24 on the supernatant of the cultures were used to determine viral titre. Results indicate that satisfactory disinfection (1000-fold reduction in 5 min) can be achieved using NaDCC and Solprogel at concentrations of 100 and 120 ppm available chlorine, respectively.

Antiviral Agents↗
PubMed1996

Detection of Legionella pneumophila serogroup 1 antigen in nonconcentrated urine and urine concentrated by selective ultrafiltration.

We evaluated a commercially available radioimmunoassay technique for detecting the soluble antigen of Legionella pneumophila serogroup 1 using concentrated and nonconcentrated urine. Concentration was achieved by selective ultrafiltration. The sensitivity of the technique was 60.9% for nonconcentrated urine and 80.4% for concentrated samples, with 100% specificity in both cases.

Antigens, Bacterial↗
PubMed1991

[Evaluation of 2 culture systems for the isolation of opportunistic mycobacteria].

The increment of infections produced by opportunist environmental mycobacteria (OEM) raises the question about the appropriateness of the conventional culture methods since they were initially designed to isolate M. tuberculosis. In this study we have comparatively evaluated the yield of a conventional culture (Löwenstein-Jensen) with respect to that of Middlebrook 7H12 (Bactec) in 396 selected samples in which OEM were isolated. Samples with commensal flora were previously subjected to a chemical homogenization-decontamination process with alkaline N-acetyl-cysteine. All cultures were sown with standard inoculates obtained from centrifugate material. The 7H12 culture showed a more rapid detection (mean: 17-18 days) and a greater effectiveness in the isolation of eventually pathogenic mycobacteria than the conventional Löwenstein-Jensen culture. The 7H12/LJ ratio for the species with high clinical relevance was: 1.3 for M. kansasii, 1.0 for M. marinum, 1.8 for M. scrofulaceum, 1.3 for M. xenopi, 1.5 for M. avium-intracellulare, 0.5 for M. chelonae, and 2.0 for M. fortuitum.

Bacteriological Techniques↗
PubMed1984

Structural changes in mitochondrial F1-ATPase induced by the removal of loosely bound nucleotides.

Mitochondrial F1-ATPase from beef heart, forms aggregates when it is depleted of loosely bound nucleotides by repeated precipitation in ammonium sulfate. Polyacrylamide gradient gel electrophoresis, in non dissociating conditions shows that the aggregate formed is a dimer (708,000 daltons). The aggregation is attributed to a conformational change of the protein as a consequence of the elimination of the nucleotides from the low affinity binding sites. This structural alteration seems to be reversible because, after addition of ATP, the aggregation is not observed on polyacrylamide gels but the catalytic properties remain unchanged. This conformational change alters the accessibility of protein sulfhydryl groups to 5,5' - dithiobis(2-nitrobenzoic acid). All these observations emphasize the importance of protein nucleotide interactions to the conformation of the mitochondrial F1-ATPase.

Animals↗
PubMed1983

A kinetic study of the interaction between mitochondrial F1 adenosine triphosphatase and adenylyl imidodiphosphate and guanylyl imidodiphosphate.

1. The presence of 5'-adenylyl imidodiphosphate, a non-hydrolysable analogue of ATP, in the solution used to assay the soluble bovine heart mitochondrial F1-ATPase produced slow competitive inhibition. If the enzyme was preincubated with the inhibitor before the substrate, MgATP, was added, a partial re-activation was obtained. 2. The slow inhibitory process showed first-order rate kinetics, and therefore it seems likely that a conformational change of the enzyme occurs following a faster binding process. A reaction scheme is suggested. At pH 7.8 the rate constant for the inhibition reaction was calculated to be 6.7 X 10(-2)s-1 and that for the re-activation 3.8 X 10(-3)s-1, with Keq. 17.6, indicating that the inhibited enzyme-inhibitor complex will be favoured over the non-inhibited enzyme-inhibitor complex. 3. The presence of 5'-guanylyl imidodiphosphate in the solution used to assay F1-ATPase produced rapid competitive inhibition, which was then slowly reversed until a steady state was reached. This might be explained by a rapid but reversible shift of the inhibition pathway induced by this non-hydrolysable analogue of ATP. A complex rate constant for the displacement of the inhibitor by the substrate of 7.6 X 10(-3)s-1 was calculated. 4. The results are discussed in the light of other recent observations about binding of 5'-adenylyl imidodiphosphate to F1-ATPase and with reference to the binding-site-change mechanism of hydrolysis of ATP by F1-ATPase.

Adenosine Triphosphate↗
PubMedDate not supplied

[Comparison of patient-ventilator synchronization during pressure support ventilation versus amplified spontaneous pattern in postoperative patients].

INTRODUCTION: Patient-ventilator desynchronization can develop during weaning from proportional-assist ventilation. Poor adaptation between ventilator assistance and the patient's ventilatory demand is termed asynchrony. OBJECTIVES: Comparative analysis of types and incidence of asynchrony in patients receiving pressure support (PS) ventilation or amplified spontaneous pattern (ASP) ventilation, to determine whether the presence of asynchrony is related to a patient's level of dyspnea or anxiety. PATIENTS AND METHODS: Eighteen patients were studied prospectively after undergoing coronary revascularization. Baseline anxiety was assessed before surgery. A pleural catheter was inserted during surgery. After surgery patients were randomly assigned to ventilation with PS mode or ASP. Flow curves, flow volume, airway pressure and pleural pressure were recorded by a BioCore CP100 monitor once the patient's work of breathing held steady between 0.3 and 0.5 J/l. The curves were recorded for 10 m on a computer for later analysis. After each recording dyspnea and anxiety were assessed. Fifty consecutive cycles per patient were analyzed, signalling in each case the start of inspiration and expiration. RESULTS: Nine hundred ventilatory cycles were analyzed to identify five types of patient-ventilator asynchrony: 1) self-cycled (SC: inspiratory assistance from the ventilator without demand by patient); 2) no effort detected (NED: patient inspiratory effort but no flow response from the ventilator); 3) interrupted support (IS: interruption of ventilatory support during patient inspiration); 4) prolonged mechanical inspiration (PMI: maintenance of ventilatory support during patient expiration), and 5) double-breath, single cycle (DBSC: sequence of inspiration-expiration-inspiration of the patient within a single assisted inspiration). Asynchronic cycles were found in all PS-ventilated patients (84 of 450; 18.7%): 9.1% SC, 4% NED, 2.2% IS, 1.5% PMI and 1.8% DBSC. Asynchronic cycles were seen in only two ASP patients (16 of 450; 3.5%); both cases were NED asynchrony. Levels of anxiety and dyspnea were slightly higher with the PS mode than with ASP but the differences were not significant (p = 0.05). CONCLUSIONS: The incidence of asynchrony during assisted ventilation is very high with the PS mode and is substantially less with ASP. Asynchrony is difficult to detect clinically and is revealed only by advanced cycle-to-cycle monitoring.

Aged↗
PubMedDate not supplied

[Application of high frequency jet ventilation during microsurgery of the larynx under suspending laryngoscopy].

OBJECTIVES: This study describes the results obtained with high frequency jet ventilation (HFJV) in 19 patients who underwent laryngeal microsurgery under suspending laryngoscopy. MATERIAL AND METHODS: After premedication and anesthetic induction with propofol (Diprivan R, ICI-Farma), we performed an endotracheal intubation (28F tube) under succinyl-choline facilitation. Conventional ventilation was started at a rate of 14-16 cpm with a minute volume of 8-10 l, and a FiO2 of 0.4 (air-oxygen). The endotracheal tube was replaced by an insufflation catheter of 2 mm internal diameter and HFJV was initiated at a rate of 100 cpm, inspiratory time equal to the 33% of the total cycle, generator pressure of 2.5-3.6 kg/cm2, and similar FiO2. We used an Ergojet CVT (Temel SA) respirator that allowed continuous monitoring of the injector released volume during each cycle (Vjet) as well as the air way pressure. Anesthesia was maintained with continuous propofol perfusion. RESULTS: During HFJV there were no significant hemodynamic alterations and surgeons considered that the condition of the surgical field was excellent. Air way pressure was maintained at low levels in all cases, although brief hypertensive episodes occurred during laryngeal manipulation. Oxygenation was satisfactory in all except one patient with chronic obstructive pulmonary disease. Conventional ventilation and HFJV did not induce significant differences in alveolar ventilation nor in PaCO2. However, during HFJV oxygenation and ventilatory levels suffered a high degree of interindividual variability. This phenomenon could be due to the existence of variable degrees of gas reflux during insufflation. CONCLUSIONS: We conclude that HFJV is a very useful technique for anesthesia in laryngeal microsurgery. However, an appropriate monitoring of ventilatory dynamics and a detailed knowledge of the influences of patient's characteristics on HFJV are required.

Adult↗
PubMedDate not supplied

[Results of functional analysis on an obstructive model of the lung using an Ergojet CVT high-frequency jet respirator. Comparison with the normal pattern].

This paper expands a previous study on functional analysis of high frequency jet (HFJV) "Ergojet CVT" ventilation module inserted in Ergotronic 3 (Temel SA) respirator. The analysis was made on a pulmonary monoalveolar model with a compliance of 50 ml/cmH2 = and a resistance of 20 cmH2O/l/se simulating an obstructive pattern. Results were also compared with those obtained in a previous study on normal lung. HFJV was applied using a jet with or without additional gas input (VE) at respiratory rates of 90, 120, 150, 180, 210, 240, 270, and 300 per minute varying in each frequency the releasing pressure of the jet (PG 1, 2, and 3 kg/cm2) and the inspiratory time (Ti 30 to 50%) giving rise to a total of 96 different situations. In each of these conditions we measured the air way pressure (Paw) and the alveolar pressure (PA) and we calculated the tidal volume (VT) and the trapped volume (VAT). These measurements were correlated with those monitored by the respirator and those obtained in the normal lung. Results show that the VT is composed almost exclusively by the jet volume (VTjet), being only of consideration the VE with a Ti of about 33% and a PG of 2 to 3 kg/cm2. When the normal pattern was compared with the obstructive one, a small reduction in VT (average of 15%) and a marked increase in peak Paw (average of 75%) were observed. The use of a Ti of 50% has no clinical interest due to the large VAT that it produces.(ABSTRACT TRUNCATED AT 250 WORDS)

High-Frequency Jet Ventilation↗