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Biomedical subjects

M Decramer

Publications and source records attributed to M Decramer.

At least 91 records · Page 5Linked to original sources
PubMed1994

A persistent unilateral lung infiltrate.

We describe the case of an intrabronchial aspirated foreign body that caused a persistent right lower lobe infiltrate. A first fibreoptic bronchoscopy demonstrated a mass with tumour-like appearance in the right bronchus intermedias, but the bronchial biopsies and the cytological smears of the bronchial aspirate failed to reveal any malignancy. During a control fibreoptic bronchoscopy, we found a chicken bone in this friable granulation tissue. It was subsequently removed with a flexible bronchofibrescope and a four-pronged forceps under topical anaesthesia.

Aged↗
PubMed1993

Triamcinolone and prednisolone affect contractile properties and histopathology of rat diaphragm differently.

Diaphragm atrophy and weakness occur after administration of massive doses of corticosteroids for short periods. In the present study the effects of prolonged administration of moderate doses of fluorinated and nonfluorinated steroids were investigated on contractile properties and histopathology of rat diaphragm. 60 rats received saline, 1.0 mg/kg triamcinolone, or 1.25 or 5 mg/kg i.m. prednisolone daily for 4 wk. Respiratory and peripheral muscle mass increased similarly in control and both prednisolone groups, whereas triamcinolone caused severe muscle wasting. Maximal tetanic tension averaged 2.23 +/- 0.54 kg/cm2 (SD) in the control group. An increased number of diaphragmatic bundles in the 5-mg/kg prednisolone group generated maximal tetanic tensions < 2.0 kg/cm2 (P < 0.05). In addition, fatigability during the force-frequency protocol was most pronounced in this group (P < 0.05). In contrast, triamcinolone caused a prolonged half-relaxation time and a leftward shift of the force-frequency curve (P < 0.05). Histological examination of the diaphragm showed a normal pattern in the control and 1.25-mg/kg prednisolone group. Myogenic changes, however, were found in the 5-mg/kg prednisolone group and, more pronounced, in the triamcinolone group. Selective type IIb fiber atrophy was found in the latter group, but not in the prednisolone groups. In conclusion, triamcinolone induced type IIb fiber atrophy, resulting in reduced respiratory muscle strength and a leftward shift of the force-frequency curve. In contrast, 5 mg/kg prednisolone caused alterations in diaphragmatic contractile properties and histological changes without fiber atrophy.

Animals↗
PubMed1993

Platypnea-orthodeoxia syndrome: a report of two cases.

Two cases of orthostatic dyspnea and arterial desoxygenation, as a postpneumonectomy complication, are reported. In one patient, echocardiography and cardiac catheterization revealed the presence of an atrial septal aneurysm, which has never been described in association with the platypnea-orthodeoxia syndrome. The other case illustrates that, despite actual technical possibilities, clinical suspicion remains a prerequisite for proper diagnosis of the entity.

Aged↗
PubMed1993

Respiratory function of the rib cage muscles.

Elevation of the ribs and expansion of the rib cage result from the co-ordinated action of the rib cage muscles. We wished to review the action and interaction of the rib cage muscles during ventilation. The parasternal intercostal muscles appear to play a predominant role during quiet breathing, both in humans and in anaesthetized dogs. In humans, the parasternal intercostals act in concert with the scalene muscles to expand the upper rib cage, and/or to prevent it from being drawn inward by the action of the diaphragm. The external intercostal muscles are considered to be active mainly during inspiration, and the internal intercostal muscles during expiration. The respiratory activity of the external intercostals is minimal during quiet breathing both in man and in dogs, but increases with increasing ventilation. Inspiratory activity in the external intercostals can be enhanced in anaesthetized animals and humans by inspiratory mechanical loading and by CO2 stimulation, suggesting that the external intercostals may constitute a reserve system, that may be recruited when the desired expansion of the rib cage is increased. The triangularis sterni is an important expiratory muscle during quiet breathing in animals, but it is not active during quiet breathing in man. However, during expiration below functional residual capacity (FRC), and during speech, laughing and coughing, the triangularis sterni is recruited and plays an increasingly important role.

Biomechanical Phenomena↗
PubMed1992

High-frequency diaphragmatic flutter: symptoms and treatment by carbamazepine.

Classic diaphragmatic flutter, a rare disorder associated with dyspnoea, thoracic or abdominal wall pain, and epigastric pulsations, is caused by involuntary contractions of the diaphragm with a frequency of 0.5-8.0 Hz. We have seen three patients with diaphragmatic flutter of higher frequency not associated with respiratory disease. The patients presented with longstanding oesophageal belching, hiccups, and retching, respectively. The diagnosis was established by the presence on electromyography of the diaphragm and scalene and parasternal intercostal muscles of repetitive discharges of 9-15 Hz. Spirographic tracings, especially those of volume or flow vs time, showed similar high-frequency oscillations superimposed on tidal respiratory movements. Treatment with carbamazepine 200-400 mg three times daily led to disappearance or great improvement of flutter and clinical symptoms in all three patients. The phenomenon was not seen in other patients with chronic hiccups or oesophageal belching or in patients without these symptoms who had undergone electromyography or spirography for other reasons. Thus, high-frequency diaphragmatic flutter seems to be a new disease entity. The response to carbamazepine, which suggests that the flutter causes the symptoms, requires further study.

Adult↗
PubMed1992

Bronchodilator properties of an inhaled leukotriene D4 antagonist (verlukast--MK-0679) in asthmatic patients.

The safety, tolerability and bronchodilator properties of inhaled verlukast (MK-0679), a new potent and selective LTD4-receptor antagonist, were studied in 12 asthmatic subjects with more than 15% increase in FEV1 after salbutamol inhalation. On three separate study days the patients inhaled placebo, verlukast 2 mg and verlukast 8 mg from a metered dose inhaler according to a randomized, double-blind, cross-over allocation schedule. Pulmonary function and tolerability were assessed regularly and after 8 h a second dose of test drug was inhaled. Thirty minutes later a beta 2-agonist dose-response curve was performed by inhaling salbutamol in cumulative doses of 200, 400 and 800 micrograms. Verlukast (8 mg) caused significant improvement in mean FEV1 from 1.5 through 8 h after inhalation as compared to placebo (P less than 0.05). The maximum change in FEV1 occurred at 2 h after inhalation with mean percent increases above baseline of 3.5, 7.7, and 9.2% after placebo, verlukast 2 mg and 8 mg, respectively. The bronchodilator response to inhaled salbutamol was significantly larger after verlukast 8 mg than after placebo pretreatment (P less than 0.05), whereas verlukast 2 mg afforded no additive bronchodilator effect. We conclude that inhalation of the LTD4-antagonist verlukast induces modest but significant bronchodilatation and may be beneficial in the treatment of asthma.

Administration, Inhalation↗
PubMed1992

Effects of broxaterol and theophylline on fatigued canine diaphragm in vivo. A randomized, controlled study.

Since broxaterol, a new beta 2-agonist, has been shown to improve contractility of fatigued canine diaphragm in vitro, a controlled, randomized study was designed to assess its effects on fatigued canine diaphragm in vivo, and compare these to the expected inotropic effects of aminophylline. Diaphragm fatigue was induced in 21 dogs using electrophrenic stimulation at 20 Hz until transdiaphragmatic pressure (Pdi) at 20 Hz was reduced to about 50% of its original value. After stabilization of fatigue, animals were randomized in three groups. Aminophylline-treated animals received an intravenous bolus of 20 mg/kg, broxaterol-treated animals were given an initial bolus of 100 micrograms/kg, and control animals obtained an equal load of saline. After 3 h, aminophylline-treated animals and broxaterol-treated animals received a second dose of 20 mg/kg and 200 micrograms/kg, respectively, whereas control animals received a second dose of saline. Pdi was measured every 30 min for 6 h. At therapeutic serum levels, theophylline did not affect Pdi at any stimulation frequency compared with control conditions. In contrast, broxaterol administration resulted in a significant (p less than 0.05) and long-lasting increase in Pdi at low stimulation frequencies. Pdi at 20 Hz thus increased by 20 +/- 16% 90 min after the first bolus, and by 36 +/- 18% 90 min after the second dose. We conclude that (1) broxaterol promotes recovery of low-frequency fatigue in a dose-dependent way, and (2) theophylline does not improve the force output of fatigued canine diaphragm in vivo.

Adrenergic beta-Agonists↗
PubMed1992

Corticosteroid-induced myopathy involving respiratory muscles in patients with chronic obstructive pulmonary disease or asthma.

We made observations on two patients with asthma and one with COPD who developed steroid-induced myopathy during prolonged treatment with high doses of corticosteroids. On admission, quadriceps force was on the average reduced to 31% of predicted (range 16 to 46% of predicted, nondominant leg), and urinary excretion of creatine in 24 h averaged 687 mg (range 275 to 1,045 mg/24 hr). Respiratory muscle involvement was evidenced by reductions in PImax and PEmax, being 38% (range 36 to 39) and 48% of predicted (range 36 to 68), respectively. Tapering of treatment with corticosteroids resulted in important recovery of quadriceps force and respiratory muscle force. In all three patients, a correlation between muscle forces and steroid dose was present during reduction of the dose. After 6 months quadriceps force averaged 62% of predicted (range 31 to 85), and PImax and PEmax reached 74% (range 52 to 92) and 92% of predicted (range 80 to 106), respectively, after 3 months. Consequently, respiratory muscle force appeared to recover faster than quadriceps force. The implications of these observations for patients treated with the usual doses of corticosteroids for shorter periods require further investigation.

Asthma↗
PubMed1992

Steroid-induced myopathy and its significance to respiratory disease: a known disease rediscovered.

Skeletal muscle myopathy is a well-known side-effect of systemically administered corticosteroids. In recent years renewed attention is being paid to the involvement of the respiratory muscles and its consequent significance in pulmonary patients. Two different clinical patterns of steroid-induced muscular changes are known. In acute myopathy and atrophy after short term treatment with high doses of steroids, generalized muscle atrophy and rhabdomyolysis occur, including the respiratory muscles. Chronic steroid myopathy, occurring after prolonged treatment with moderate doses, is characterized by the gradual onset of proximal limb muscle weakness and may be accompanied by reduced respiratory muscle force. Animal studies demonstrated diaphragmatic myopathy and atrophy similar to the alterations in peripheral skeletal muscles. Fluorinated steroids induced selective type IIb (fast-twitch glycolytic) fibre atrophy, resulting in changes in contractile properties of the diaphragm. Non-fluorinated steroids may also induce histological, biochemical and functional alterations in the diaphragm. Observations in patients with collagen vascular disorders and with asthma and chronic obstructive pulmonary disease (COPD) underline the potential hazards of treatment with corticosteroids to respiratory muscle structure and function.

Acute Disease↗
PubMed1991

Effects of aminophylline on respiratory muscle interaction.

We studied the effects of aminophylline on respiratory muscle interaction during quiet breathing by measuring (1) changes in rib cage and abdominal cross-sectional area, (2) tidal volume, (3) abdominal and esophageal pressure, (4) diaphragm and parasternal intercostal electromyogram (EMG) and parasternal intercostal intramuscular pressure, and (5) triangularis sternl and transversus abdominis EMG, in 14 supine anesthetized dogs. Measurements were done before and 5 and 10 min after administration of progressively increasing doses of aminophylline, reaching a total dose of 5, 10, 20, 40, and 80 mg/kg. In 12 of 14 dogs after aminophylline administration, quiet inspiration became biphasic, or if inspiration was already biphasic under control conditions, the first phase was clearly enhanced after aminophylline administration. Biphasic inspiration was defined as an inspiratory pattern in which rib cage and abdominal expansion showed two distinct phases. First, the onset of inspiration was characterized by a sudden increase in rib cage cross-sectional area often associated with a decrease in abdominal dimensions. During this initial part the parasternals and the diaphragm were electrically silent, confirming that it was achieved by relaxation of expiratory muscles. Further inspiration occurred predominantly through expansion of the abdomen. In the first phase, a pressure drop in the parasternal intercostals was present, presumably due to passive shortening of these muscles caused by expiratory muscle relaxation. On the average, 42 +/- 28% of the rib cage expansion was due to expiratory muscle relaxation at a dose of 80 mg/kg versus 17 +/- 21% under control conditions (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Aminophylline↗
PubMed1991

Effects of theophylline on canine diaphragmatic contractility and fatigue.

To distinguish the effects of theophylline on respiratory muscle contractility from alterations in respiratory muscle interaction or blood flow, we examined in vitro contractile properties and fatigue of canine diaphragm in two series of experiments. In the first series, a 40-mg/kg aminophylline infusion was given to dogs, and diaphragm strips were removed for in vitro study when stable tissue fixation of the drug was reached. Compared with control bundles examined before aminophylline infusion, no alterations in twitch tension, tetanic tension, or force-frequency characteristics were observed. Moreover, theophylline-treated strips fatigued faster than control strips, whether subjected to repetitive submaximal or maximal contractions (p less than 0.01). In the second series, diaphragm bundles were equilibrated with high theophylline doses (400 mg/L) in vitro, and inotropic effects compared with the results in the first series. Supratherapeutic theophylline concentrations increased force development at low stimulation frequencies (p less than 0.05 at 10 Hz) and significantly elevated twitch-tetanus ratio (p less than 0.01) but did not protect against development of in vitro muscle fatigue. Poor penetration of theophylline in diaphragm bundles in vitro was excluded, since drug concentrations in the muscle bundle and the muscle bath were virtually equal. We conclude that diaphragmatic tissue concentrations correlate well with therapeutic serum and supratherapeutic bath levels and that only high theophylline concentrations increase canine diaphragmatic contractility in vitro. None of the theophylline concentrations studied could protect diaphragm bundles against the development of low- or high-frequency fatigue in vitro.

Animals↗
PubMed1990

Respiratory changes in diaphragmatic intramuscular pressure.

We attempted to measure diaphragmatic tension by measuring changes in diaphragmatic intramuscular pressure (Pim) in the costal and crural parts of the diaphragm in 10 supine anesthetized dogs with Gaeltec 12 CT minitransducers. During phrenic nerve stimulation or direct stimulation of the costal and crural parts of the diaphragm in an animal with the chest and abdomen open, Pim invariably increased and a linear relationship between Pim and the force exerted on the central tendon was found (r greater than or equal to 0.93). During quiet inspiration Pim in general decreased in the costal part (-3.9 +/- 3.3 cmH2O), whereas it either increased or slightly decreased in the crural part (+3.3 +/- 9.4 cmH2O, P less than 0.05). Similar differences were obtained during loaded and occluded inspiration. After bilateral phrenicotomy Pim invariably decreased during inspiration in both parts (costal -4.3 +/- 6.4 cmH2O, crural -3.1 +/- 0.6 cmH2O). Contrary to the expected changes in tension in the muscle, but in conformity with the pressure applied to the muscle, Pim invariably increased during passive inflation from functional residual capacity to total lung capacity (costal +30 +/- 23 cmH2O, crural +18 +/- 18 cmH2O). Similarly, during passive deflation from functional residual capacity to residual volume, Pim invariably decreased (costal -12 +/- 19 cmH2O, crural -12 +/- 14 cmH2O). In two experiments similar observations were made with saline-filled catheters. We conclude that although Pim increases during contraction as in other muscles, Pim during respiratory maneuvers is primarily determined by the pleural and abdominal pressures applied to the muscle rather than by the tension developed by it.

Animals↗
PubMed1990

Respiratory changes in parasternal intercostal intramuscular pressure.

In an attempt to obtain insight in the forces developed by the parasternal intercostal muscles during breathing, changes in parasternal intramuscular pressure (PIP) were measured in 14 supine anesthetized dogs using a microtransducer method. In six animals, during bilateral parasternal stimulation a linear relationship between contractile force exerted on the rib and PIP was demonstrated (r greater than 0.95). In eight animals, during quiet active inspiration, substantial (55 +/- 11.5 cmH2O) PIP was developed. During inspiratory resistive loading and airway occlusion the inspiratory rise in PIP increased in proportion to the inspiratory fall in pleural pressure (r = 0.82). Phrenicotomy and vagotomy resulted in an increase in the inspiratory rise in PIP of 21% and 99%, respectively. During passive deflation, when the parasternal intercostals were passively lengthened, large rises (320 +/- 221 cmH2O) in intramuscular pressure were observed. During passive inflation intramuscular pressure remained constant or even decreased slightly (-8 +/- 25 cmH2O) as expected on the basis of the passive shortening of the muscles. PIP thus invariably increased when tension increased either actively or passively. From PIP it is clear that the parasternals exert significant forces on the ribs during respiratory maneuvers.

Animals↗
PubMed1990

Theophylline minimally alters contractile properties of canine diaphragm in vitro.

We examined the effects of theophylline on contractile properties and high-frequency fatigue of canine diaphragm in vitro. Eighteen diaphragm muscle bundles were obtained from 10 anesthetized dogs and equilibrated in oxygenated Krebs solution to 100, 200, or 300 mg/l theophylline. These bundles were compared with 18 matched control bundles from the contralateral hemidiaphragm. No statistically significant differences in twitch tension, tetanic tension, twitch-to-tetanus ratio, time to peak tension, or half-relaxation time were observed. Concentrations of 300 mg/l theophylline, however, significantly (P less than 0.05) increased force production at 10 Hz by 32%. A similar tendency was present at lower concentrations and exhibited a clear dose-response behavior. High-frequency fatigue was similar in control and theophylline-treated bundles. We conclude that supratherapeutic in vitro concentrations of theophylline do not increase maximal tetanic tension and do not protect against muscle fatigue but potentiate relative force production at low stimulation frequencies. This relatively small effect cannot be explained by poor diffusion of the drug in the muscle bundle, because theophylline concentrations in the muscle bath and in the muscle bundle were virtually identical. Moreover, it remains unclear whether this potentially beneficial effect can be achieved at in vivo attainable serum concentrations.

Animals↗