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Biomedical subjects

T Similowski

Publications and source records attributed to T Similowski.

At least 73 records · Page 4Linked to original sources
PubMed1996

[Iatrogenic disorders in the active respiratory systems (respiratory center and its performance].

Amongst the undesirable effects of medical intervention which touch on the respiratory apparatus one can distinguish schematically those disorders which affect the "passive respiratory system" (lungs, pleura, bronchi and vessels) and those which concern the "active respiratory system (SRA)" (nerve centres, respiratory muscles) which are less often described. After a brief reminder of the principles and limits of the available methods of investigation, this chapter reviews the different iatrogenic disorders of SRA according to their level and their aetiology. Peripheral disorders are touched on such as alterations of phrenic conduction (with particular mention of satellite lesions from cardiac surgery), those of neuromuscular transmission (most often induced by medication) and of intrinsic muscular properties (mainly steroid induced myopathies). Central disorders are described principally as the respiratory effects of neurotropic and non-neurotropic medications and the harmful effects of different substances on the sleep/respiration interaction. The secondary effects of therapy on SRA are all the more marked if there are underlying respiratory or neuromuscular disturbances which allow a large place for preventive measures. The diagnosis is made difficult by the complexity of the structures and functions involved and it is clear that the development of pathophysiological studies, which are still too scarce, should enable better understanding of their clinical significance.

Diagnosis, Differential↗
PubMed1995

[Diagnosis and treatment of acute respiratory failure in chronic obstructive respiratory insufficiency].

Acute respiratory failure of chronic obstructive pulmonary disease is a common event. Vital prognosis is seldom directly engaged, and careful management generally allows patients to resume their prior respiratory status, and long term therapeutic procedures such as oxygen therapy or home ventilation to be discussed. Diagnosis is often simple, and evaluation of severity, therapeutic strategy, and etiology research are carried out simultaneously. The first step of treatment is controlled oxygen therapy. When conservative treatment fails to achieve safe level of PaO2 without inducing threatening hypercapnia, mechanical ventilation is required. Recent data strongly suggest that non invasive inspiratory pressure support brings major benefits in terms of morbidity and mortality.

Acute Disease↗
PubMed1995

Baclofen therapy for chronic hiccup.

Chronic hiccup is a rare but potentially severe condition, that can be symptomatic of a variety of diseases, or idiopathic. Many therapeutic interventions have been reported, most often as case reports. Among other drugs, baclofen has been suggested as a therapy for chronic hiccup. In a large series of patients, we have evaluated its therapeutic position. In patients with chronic hiccup, defined as hiccup spell or recurring hiccup attacks lasting more than 7 days, investigation of the upper gastro-oesophageal tract (fibroscopy, manometry, and pH monitoring) was systematically performed. Most patients had tried numerous drugs in the past, without success. Baclofen was used as a first treatment in patients without evidence of any gastro-oesophageal disease (n = 17), and was undertaken only after full treatment of such disease (n = 55) had failed to solve the hiccup problem (n = 20). Baclofen has, therefore, been administered to 37 patients with chronic hiccup (average duration 4.6 yrs). Baclofen produced a long-term complete resolution (18 cases) or a considerable decrease (10 cases) of hiccups in 28 of the 37 patients. There was no significant difference between patients with or without gastro-oesophageal disease. We conclude that so-called idiopathic chronic hiccup often results from gastro-oesophageal abnormalities. Also, if controlled studies confirm our encouraging results, baclofen can be a major element in the treatment of chronic hiccup that is idiopathic, or that cannot be helped by treatment of gastro-oesophageal diseases.

Anti-Ulcer Agents↗
PubMed1995

Physical examination of the adult patient with respiratory diseases: inspection and palpation.

Inspection of the thorax identifies the breathing position adopted by the patient, the shape of the thorax, the dynamics of respiration (breathing pattern, symmetry of expansion, mechanics and synchrony of rib cage and abdominal movements). Inspection of the neck adds useful information, particularly with respect to the dynamics of breathing. Palpation ascertains the signs suggested by inspection with respect to the mechanics of breathing. It also assesses the state of the pleura and pulmonary parenchyma by studying the tactile fremitus. It integrates extrarespiratory signs, such as enlarged lymph nodes or breast abnormalities. Extrathoracic respiratory signs should also be systematically looked for, including cyanosis, finger deformation, pulsus paradoxus, and pursed lips breathing. Interobserver agreement about respiratory signs has repeatedly been studied, and generally found to be low, as are clinical-functional correlations. However, some data on chronic obstructive pulmonary disease (COPD), asthma or pulmonary embolism are available. From the description of some signs and the current knowledge about their operative values, it appears that much clinical research remains necessary to better define the precise diagnostic value of a given sign. The impact of training on diagnostic performance also has to be defined. Both of these aspects should allow clinicians to optimize the way in which they use their hands and eyes to conduct respiratory diagnosis, as well as the way they teach respiratory symptomatology.

Adult↗
PubMed1995

[Bibliometry of biomedical periodicals].

Bibliometry or the science citation index is a quantitative evaluation of periodical literature, biomedical or others. It depends above all on an analysis of citations which allows for a calculation of different indices characterising and classifying journals (number of articles published, frequency of citation, impact, topicality...). The applications of bibliometry are varied from the administration of library collections to the appreciation of the significance of a review in its own speciality area. By extension the bibliometry index are sometimes used to evaluate the importance of a discipline in the literature, the place of a nation within a discipline, the significance of certain opinions or the quality of research. The intrinsic limits of bibliometry are such that this last application should be handled with caution. In effect, various biases can mechanically affect the value of different indices and particularly the fact that an article appearing in a prestigious review should not prejudge its quality such as the relevance of the question posed, the validity of the methodology employed or the accuracy of the results. For this, the study of citations is insufficient and some qualitative or semi-quantitative criteria bearing on the contents of the article should be used (critical reading, gate analysis, etc.) This general review has, as its aim, to expose both the definitions and limits of bibliometry illustrating them with some information calculated from the principal respiratory journals.

Bias↗
PubMed1994

Late CD8+ lymphocytic alveolitis after allogeneic bone marrow transplantation and chronic graft-versus-host disease.

Late-onset interstitial pneumonitis following allogeneic bone marrow transplantation (BMT) is a rare condition usually caused by a variety of infective agents, although in some cases these are idiopathic. We investigated noninfectious late interstitial pneumonitis with lymphocytic alveolitis in seven allogeneic BMT recipients using bronchoalveolar lavage (BAL), lymphocyte phenotyping analysis, CT lung scans, and pulmonary function tests. The results were compared with those of a control group composed of similar patients with no pulmonary symptoms. Of 65 long-term survivors, seven were included in the study. All had chronic graft-versus-host disease (GVHD) and developed interstitial pneumonitis a median of 210 d (range 120 to 445 d) after BMT. BAL revealed lymphocytosis, with an overall expansion of CD8+ subsets (38 to 90%). Lymphocytic alveolitis was not observed in the control group. Pulmonary function tests revealed a restrictive syndrome, and biopsy samples obtained from 2 patients showed interstitial lymphoid infiltration with fibrosis of the alveolar walls. Of the 7 patients, six were cured by starting immunosuppressive drugs or increasing the dosage with a drastic improvement in respiratory symptoms within 1 mo. These findings suggest that CD8+ alveolitis may be observed in late interstitial pneumonitis in allogeneic BMT recipients and may be a pulmonary manifestation of chronic GVHD.

Adult↗
PubMed1994

Inspiratory muscle testing in stable COPD patients.

Exploration of inspiratory muscles in stable chronic pulmonary disease patients can be important in the investigation of a respiratory handicap unsatisfactorily explained by alterations of the passive respiratory system, or in the follow-up of patients undergoing treatments that can interfere with muscle function. Compensatory mechanisms tend to counterbalance the deleterious effects of hyperinflation in these patients, and precise clinical data are needed in order to avoid mistakes due to underverified hypotheses. Investigation of inspiratory muscle function requires the study of output data under various states of activity of the system. As outputs, volume displacement lacks specificity, pressure measurements can be more specific but are at times invasive and should be associated with lung volume measurements, electromyography is methodologically complex, nonquantitative and of poor reproducibility. Voluntary manoeuvres depend upon subject co-operation, and do not allow partitioning of output between the action of different muscle groups. Transcutaneous electrical phrenic nerve stimulation is devoid of these inconveniences, but it explores only one muscle (the diaphragm) under conditions that are not "natural" (relaxed rib cage). Recently, perspectives for easier clinical assessment of inspiratory muscle function in chronic obstructive pulmonary disease patients have been opened by cervical magnetic stimulation, better understanding of the meaning of mouth pressure in relationship to phrenic stimulation, and development of noninvasive tests, such as nostril pressure during sniff or phonomyography. If validated, such tests should provide a reasonably limited panel of clinical tools to better appreciate muscle function in this setting.

Diaphragm↗
PubMed1994

Clinically relevant diaphragmatic dysfunction after cardiac operations.

Phrenic nerve injury and diaphragmatic dysfunction can be induced by cardiac operation. The clinical consequences are not well-established. We evaluated 13 consecutive patients over a 2-year period with unexplained and prolonged difficulties in weaning from mechanical ventilation. The mean time of measurement from the operation day was 31 +/- 19 days (range 8 to 78). With the same technique we also evaluated 12 control patients: four patients at day 1 after cardiac operation while they were still intubated; four normally convalescing patients at day 7 or 8 after cardiac operation; and four patients who required prolonged mechanical ventilation because of another identified cause after cardiac operation. Diaphragmatic function was evaluated at the bedside from esophageal and gastric pressure measurements. A low or negative ratio of gastric pressure swing to transdiaphragmatic pressure swing, indicative of diaphragm dysfunction, was found in all 13 patients (mean -0.39 +/- 0.64). The difference between the 13 patients and all control groups was found to be highly significant. Transdiaphragmatic pressure measured during a maximal voluntary inspiratory effort and transdiaphragmatic pressure measured during a short, sharp sniff were markedly diminished (28 +/- 18 cm H2O and 13 +/- 15 cm H2O, respectively) in the 13 patients, significantly different from values in the four control patients studied at day 7 or 8. Transdiaphragmatic pressure measured after magnetic stimulation in four patients was also markedly reduced (7 +/- 5 cm H2O) as compared with normal theoretic values. Aminophylline infusion had no effect on any of these parameters. In one of two patients evaluated a second time, about 5 weeks later, a marked improvement was observed. Estimating the prevalence of clinically relevant diaphragmatic dysfunction, we found it to be 0.5% when no topical cooling was used and 2.1% when iced slush with no insulation pad was added for myocardial protection (p < 0.005). The most striking finding was that the clinical course of the 13 patients was marked by severe intercurrent events, including cardiorespiratory arrest after early tracheal extubation in 5 patients, nosocomial pneumonia in 11, prolonged mechanical ventilation in all (58 +/- 41 days), and a fatal outcome in 3. We conclude that prolonged postoperative diaphragmatic dysfunction may cause severe life-threatening complications after cardiac operation and can be limited to some extent by avoiding the use of iced slush topical cooling of the heart.

Adult↗
PubMed1993

Assessment of diaphragm function using mouth pressure twitches in chronic obstructive pulmonary disease patients.

The relative invasiveness of the balloon catheter technique in measuring twitch transdiaphragmatic pressure (Pdit) limits its clinical use. By phrenic stimulation we obtained swings in mouth pressure (Pmt) in six COPD patients (age 50 to 72, FEV1 18 to 48% of predicted) at relaxed FRC (rFRC) and during graded inspiratory efforts (IE; twitch occlusion, TO). At rFRC, Pmt was damped and time lagged relative to the esophageal pressure twitch (Pes(t)), as if pressure had equilibrated through an RC system. Pmt was not correlated with Pdit. Conversely, Pmt and Pes(t) were always well matched during IE [Pmt = 0.971 (SEM +/- 0.028) Pes(t), r > 0.89], possibly in relation to a decrease in upper airway compliance or more uniform pleural pressure swings. Pmt decreased with the level of voluntary diaphragmatic contraction (Pdivol) in proportion to Pdit, reflecting a progressive increase in the level of diaphragm activation. During IE, Pmt was closely related to the voluntary mouth pressure in five subjects but not in the remaining subject, indicating intersubject variability in the level of diaphragmatic recruitment relative to other inspiratory muscles. We submit that measuring Pm during inspiratory efforts upon which bilateral phrenic stimulation is superimposed offers a relatively simple method for the assessment of diaphragm activation, potentially applicable in the clinical field.

Aged↗
PubMed1993

Force-frequency relationships of in vivo human and in vitro rat diaphragm using paired stimuli.

Supramaximal stimuli, with time intervals of 100 ms (10 Hz) to 10 ms (100 Hz), were delivered in pairs to the phrenic nerves, bilaterally, in five seated normal subjects, while transdiaphragmatic pressure swings (Pdi,s) were recorded at relaxed end-expiratory lung volume with airways closed. In fresh diaphragms, Pdi,s increased between 10-20 Hz and reached a plateau between 20-30 Hz. Diaphragmatic fatigue decreased Pdi,s at all frequencies. Pdi,s was assumed to be the sum of two successive responses (T1+T2), T1 being constant at any frequency and equal to a single twitch, T2 being obtained by subtraction. We found that T2 amplitude, which was significantly reduced after fatigue, was fully returned to normal after 15 min rest at high, not at low, stimulation frequencies. The ratio of T2 at 10 Hz over 100 Hz (T2(10/100)) thus decreased from 1.33 +/- 0.05 before fatigue to 0.97 +/- 0.12 after fatigue, and to 0.81 +/- 0.06 after 15 min rest. Similar results were obtained in isolated rat diaphragmatic strips stimulated and fatigued in vitro, from which we found a highly linear relationship (r = 0.94, p < 0.001) between the ratio of T2(10/100) and that of tetanic force at 10 Hz over 100 Hz (P10/100). We conclude that phrenic nerve paired twitches provide similar information when obtained from phrenic tetanic stimulation in terms of diaphragmatic contractility, and the decrease in T2(10/100) ratio indicates diaphragm low frequency fatigue.

Animals↗
PubMed1992

[Chronic hiccups].

We report 18 cases of chronic hiccup (defined as lasting for more than 48 hours) in adults. Among the numerous possible causes, reflux esophagitis proved to be by far the most frequent (50% of the cases). However, hiccup often initiated a self-perpetuating vicious circle. This is possibly because hiccup per se can give esophageal dyskinesia, which in turn leads to gastro-esophageal reflux. The treatment was difficult and whenever possible has been directed chiefly towards the cause. However hiccup remained intractable in many cases even after a possible cause had been adequately cured (e.g., successful Nissen procedure in reflux cases). Central nervous system depressants and myorelaxing drugs were not very helpful, except for baclofen (initial response rate = 60%).

Adult↗
PubMed1992

Effect of fatigue on diaphragmatic function at different lung volumes.

The transdiaphragmatic pressure twitches (PdiT) in response to single maximal shocks delivered bilaterally to the phrenic nerves were recorded as a function of lung volume when the diaphragm was fresh and when fatigued. All relationships were linear and negatively sloped (all r greater than 0.85). From these relationships PdiT was found to decrease with fatigue more rapidly and to recover more quickly at high than at low lung volumes. Complete recovery of PdiT at all lung volumes was greater than 1 h. Contraction and relaxation rate constants of PdiT did not change significantly with fatigue. We conclude that fatigue affects diaphragm contractility more at high than at low lung volumes and that changes in diaphragm contractility are best reflected in the measurement of PdiT as a function of lung volume.

Adult↗