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At least 739 records · Page 41Linked to original sources
PubMed2004

[Postnatal maturation of the diaphragm muscle: ultrastructural and functional aspects].

OBJECTIVE: In the diaphragm muscle, postnatal maturation is associated with major histological and biochemical modifications, as well as a progressive development of the sarcoplasmic reticulum (SR), which in turn are responsible for the progressive postnatal improvement in diaphragmatic contractility. However, the mechanisms by which postnatal maturation induces this improvement in diaphragmatic contractility remain poorly understood and controversial. The aim of this review is to analyze the data from the literature regarding the process involved in the postnatal improvement in diaphragmatic contractility. DATA SOURCES: References obtained from Pubmed((R)) databank using keywords (diaphragm muscle, postnatal maturation, contractility, muscular fatigue, cross-bridge). DATA SYNTHESIS: From a cytological point of view, the postnatal development of the diaphragm muscle is processed in two successive generations of fiber types, corresponding to the progressive adaptation of the diaphragm muscle to its physiological function. Indeed, the proportion in type I (slow, aerobic) and type IIB fibers (fast, anaerobic) progressively increases with postnatal maturation, while the proportion in type IIA fibers (fast, intermediate) progressively decreases. The histochemical classification of the type of fiber corresponds to the expression of the different isoforms of myosin heavy chains (MHC). Two types of MHC: MHC embryologic (MCH-emb) and MHC neonatal (MCH-neo), and one type of myosin light chains (MLC) are expressed in the foetal skeletal muscles, then are progressively eliminated during postnatal maturation. For many authors, this progressive transition from immature MHC (MCH-emb and neo) to adult MHC (by chronological order of appearance: MHC-2A, MHC-lente, MHC-2X, MHC-2B) could be responsible for the progressive improvement in postnatal diaphragmatic contractility. This transition could be modulated by external factors, mainly including neural and hormonal stimuli. For others, this transition in MHC expression do not play a major role, and other factors, including the postnatal maturation of the ryanodine receptor (RyR) or developmental changes in cross-bridges (CB) properties should play a central role. The most recent hypotheses proposed included the possibility of a postnatal transition in the expression of structural proteins, which are playing a major role in the maintenance of the stability of the sarcomer, and therefore in force generation.

Animals↗
PubMed1994

Inspiratory muscle training in patients with Duchenne muscular dystrophy.

PURPOSE: The aim of this study was to assess the usefulness of a specific inspiratory muscle training in Duchenne muscular dystrophy (DMD). PATIENTS AND METHODS: Fifteen patients with DMD started 6 months of training the inspiratory muscles and 15 patients served as a control group. Pulmonary and inspiratory muscle function parameters were assessed 3 months before and at the beginning of training, in the first and third month of training, at the end, and 6 months after its cessation. Maximal sniff assessed esophageal and transdiaphragmatic pressure values served as indices for global inspiratory muscle strength and diaphragmatic strength, respectively. Inspiratory muscle endurance was assessed by the length of time a certain inspiratory task could be maintained. RESULTS: In 10 of the 15 patients, respiratory muscle function parameters improved significantly after 1 month of training. Further improvements were to be seen after 3 and after 6 months. Even 6 months after the end of training, those effects remained to a large extent. In the other five patients, there was no such improvement after 1 month of training, which was therefore discontinued. All these five patients had vital capacity values of less than 25 percent predicted and/or PaCO2 values of more than 45 mm Hg. The 15 control patients had no significant change in their respiratory muscle function parameters. CONCLUSION: We conclude that a specific inspiratory muscle training is useful in the early stage of DMD.

Adolescent↗
PubMed2000

Surgical intervention for emphysematous pulmonary regions in a postoperative infant with congenital diaphragmatic hernia.

A postoperative infant with congenital diaphragmatic hernia (CDH) developed extrinsic obstruction of the trachea by the innominate artery that ensued from unequal expansion of the lungs followed by left mediastinal shift. Septation of the anterior mediastinum prevented unequal expansion of the lungs, and elongation of the innominate artery improved proximal airway obstruction. Prolonged artificial ventilation, however, resulted in the emphysematous bullae in the left lung. Lung volume reduction surgery (LVRS), at 3 years of age, ameliorated the respiratory distress and resulted in good weight gain. Surgical intervention, including LVRS, should be considered to improve respiratory disturbance caused by difference in compliance of the lungs in children.

Hernia, Diaphragmatic↗
PubMed2004

Unilateral nephrectomy as palliative therapy in an infant with autosomal recessive polycystic kidney disease.

Prenatal diagnosis of autosomal recessive polycystic kidney disease (ARPKD) implies a dire prognosis. Neonates affected by the more severe variants of ARPKD suffer respiratory failure caused by massive kidneys that restrict diaphragmatic expansion and result in pulmonary hypoplasia. Afflicted infants who survive the neonatal period and gain adequate respiratory function may subsequently suffer from an inability to tolerate enteral nutrition due to abdominal compression from the massive kidney and the systemic effects of renal compromise. Palliative unilateral or bilateral nephrectomy may be considered in rare instances to facilitate pulmonary expansion and gastrointestinal function. We report on an infant with severe ARPKD who was able to tolerate enteral nutrition only after left nephrectomy.

Humans↗
PubMed1993

Effect of ischemia-reperfusion on diaphragm strength and fatigability.

Although episodes of prolonged limb skeletal muscle ischemia followed by periods of reperfusion and reoxygenation are known to elicit free radical-mediated injury, the susceptibility of the diaphragm to this form of injury is not known. The purpose of the present study was to determine the effects of a period of severe partial ischemia, followed by reperfusion, on diaphragm contractile function. We also examined the effect of administration of a free radical scavenger, dimethyl sulfoxide (DMSO), on the diaphragmatic response to ischemia-reperfusion. Experiments were performed on three groups of anesthetized dogs in which a vascularly isolated strip of diaphragm was dissected in situ: 1) a control group in which the diaphragm was perfused at the ambient systemic pressure, 2) a group in which the diaphragm was made ischemic for 3 h and reperfused for 1 h, and 3) a group given DMSO before periods of ischemia and reperfusion. In all groups, we measured diaphragm strip strength and fatigability; we also assessed diaphragm blood flow at several levels of contractile activity. Periods of ischemia, followed by reperfusion, were found to produce a downward shift of the diaphragm force-frequency relationship and also to markedly increase diaphragm fatigability. Diaphragm blood flow at rest and at low levels of contractile activity was unaffected by ischemia-reperfusion, but the flow achieved during fatiguing contractions was appreciably lower than that in nonischemic control animals. DMSO administration protected the diaphragm from the effects of ischemia-reperfusion, preventing alterations in fatigability and strength. Diaphragm flow in DMSO-treated animals was similar to that in controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

[Pleural talc administration under thoracoscopy in the treatment of pneumothorax. Study of a series of 109 cases treated over a 3-year period].

There has recently been renewed interest in thoracoscopy. Among its indications we consider talc therapy for a pneumothorax particularly worthy of interest. We report the three year results obtained on a series of 109 pneumothoraces. The indication for thoracoscopy were considered either for a chronic pneumothorax (failure of drainage after 8 days) or for a recurrent pneumothorax. We perform this technique under local anaesthetic with talc therapy given direct vision on the macroscopic lesions encountered. Patients were in hospital for a mean of five days. The results were as follows: Lung appearance. Normal 19%-Dystrophic bullae and giant bullae 41%. blebs: 13%-a visible breach 14%-Diverse anomalies 13%. The immediate failures with talc numbered 6 (5%) each time from the chronic pneumothorax group. They were treated surgically. There were 7 recurrences after talc therapy, 5 were partial recurrences requiring no further treatment and two total relapses were surgically treated. The radiological sequelae appeared minimal. On 5 occasions pleural discomfort hindered the diaphragmatic movement, in the other cases the radiological sequelae consisted of discrete pleural thickening. 42 patients had respiratory function testing and no abnormalities were noted. The failures or recurrences in the talc treated patients were all in the recurrent pneumothorax and were only 13 cases (12%). Thus thoracoscopy is a treatment of choice in the treatment of recurrent pneumothorax, and often replaces surgery. In certain cases (pneumothorax in respiratory failure) it is only possible treatment.

Adolescent↗
PubMed1983

[Pulmonary and diaphragmatic mechanics and respiratory movements in patients with heart valve disease].

Pulmonary ventilation, and pulmonary and diaphragmatic mechanics were examined in 41 patients with valvular defects and circulatory insufficiency of varying severity. The hemodynamic function of the thoraco-abdominal pump mechanism was shown to be disrupted in valvular disease, resulting in reduced capacity of "sucking" blood towards the heart, and increased capacity of "pumping" it on a compensatory basis. It is concluded that insufficiency of the thoraco-abdominal pumping mechanism can contribute to the progress of hemodynamic disorders and the development of associated respiratory and circulatory disturbances.

Adolescent↗
PubMed1997

[Diaphragm kinetics coupled with spirometry. M-mode ultrasonographic and fluoroscopic study; preliminary results].

Most techniques used so far for the evaluation of diaphragm kinetics are either invasive (electromyography, fluoroscopy), or indirect (respiratory pressures, impedance plethysmography). The aim of this study was to determine whether assessment with ultrasound or fluoroscopy differed, and which technique appeared more suitable in the investigation of quantitative hemidiaphragmatic displacement. Six patients (3 female, 3 male, aged 29 to 40) without respiratory disease were studied during systematic X-Ray chest examination, spirometry, and abdominal sonography. The amplitude of the right diaphragm motion could be measured in all patients with M-mode sonography as well as with fluoroscopy. The vertical ascending motion of the diaphragm measured by M-mode sonography, reached 60% of its maximum amplitude at 50% of inspiratory capacity. There was a significant correlation between the maximum amplitude of diaphragm motion as measured by M-mode sonography (5.8 +/- 0.4 cm; r = 0.89; p = 0.019) or fluoroscopy (5.6 +/- 0.7 cm; r = 0.84; p = 0.036) and the inspiratory capacity (2.73 +/- 0.39 l). M-mode sonography has technical, quantitative and qualitative advantages over fluoroscopy and should be the method of choice in the investigation of suspected diaphragmatic movement disorder. When coupled with other techniques like spirometry, this technique could represent a useful adjunct to functional respiratory studies.

Adult↗
PubMed1988

Postinflammatory increase of lymphatic absorption from the peritoneal cavity: role of diaphragmatic stomata.

During the healing phase of a chemical peritonitis in rats, absorption of various inocula from the peritoneal cavity into the draining lymph nodes is increased. Heretofore, this phenomenon has been attributed to fibrosis and shrinkage of the greater omentum. The loss of the sequestering function of the omentum allows the inoculum more ready access to the lymphatic vessels in the diaphragm where it is absorbed. In the present work, it is demonstrated that the chemical peritonitis also widens the stomata in the roofs of the diaphragmatic lymphatic lacunes. Both increased access and larger openings contribute to enhanced lymphatic absorption in the postinflammatory state.

Absorption↗
PubMed1995

Severe hypercapnia after low-flow oxygen therapy in patients with neuromuscular disease and diaphragmatic dysfunction.

OBJECTIVE: To increase the general awareness of the possible exacerbation of hypercapnia by the administration of low-flow oxygen in patients with neuromuscular disorders. DESIGN: We retrospectively reviewed the medical records of 118 consecutive adult patients with a diagnosis of neuromuscular disease who underwent phrenic nerve conduction studies during a 5-year period, and we analyzed pulmonary function data for 8 patients who underwent arterial blood gas studies before and after the administration of low-flow oxygen. MATERIAL AND METHODS: In the eight patients with neuromuscular disease and diaphragmatic dysfunction (three with polymyositis, three with amyotrophic lateral sclerosis or nonspecific motor neuron disease, and one each with inflammatory motor neuropathy and chronic poliomyelitis), we analyzed the response of the arterial carbon dioxide tension (PaCO2) after low-flow supplemental oxygen therapy (0.5 to 2 L/min). Linear analysis was used to attempt to find correlations between respiratory variables and the PaCO2 response after oxygen therapy. RESULTS: For the overall study group, the mean PaCO2 increased 28.2 +/- 23.3 torr after low-flow oxygen treatment; in five patients, it increased by 27 torr or more. Four patients who were subsequently treated with nocturnal assisted ventilation were able to use supplemental oxygen during the day with less severe hypercapnia. Statistical analysis failed to reveal specific correlations between increased PaCO2 values after oxygen therapy and any respiratory variables. CONCLUSION: In patients with neuromuscular disease and diaphragmatic dysfunction, even low-flow supplemental oxygen should be administered with caution, and assisted ventilation should be strongly considered as an initial intervention.

Adult↗
PubMed1988

Functional characteristics of canine costal and crural diaphragm.

We estimated the in situ force-generating capacity of the costal and crural portions of the canine diaphragm by relating in vitro contractile properties and diaphragmatic dimensions to in situ lengths. Piezoelectric crystals were implanted on right costal and left crural diaphragms of anesthetized dogs, via midline laparatomy. With the abdomen reclosed, diaphragm lengths were recorded at five lung volumes. Contractile properties of excised muscle bundles were then measured. In vitro force-frequency and length-tension characteristics of the costal and crural diaphragms were virtually identical; their optimal force values were 2.15 and 2.22 kg/cm2, respectively. In situ, at residual volume, functional residual capacity (FRC), and total lung capacity the costal diaphragm lay at 102, 95, and 60% of optimal length (Lo), whereas the crural diaphragm lay at 88, 84, and 66% of Lo. Muscle cross-sectional area was 40% greater in costal than in crural diaphragms. Considering in situ lengths, cross-sectional areas, and in vitro length-tension characteristics at FRC, the costal diaphragm could exert 60% more force than the crural diaphragm.

Animals↗