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PubMed1999

Reversal of impaired calcium homeostasis in the rat diaphragm subjected to Monocrotaline-induced pulmonary hypertension.

Monocrotaline (MCT) pneumotoxicity is known to alter the structure of pulmonary vascular wall and impairs endothelial cell function resulting in pulmonary hypertension. Its effect on the diaphragm muscle has not yet been elucidated. This study examines the effect of MCT pneumotoxicity on calcium transport in the rat diaphragm. Pulmonary hypertension induced by MCT pneumotoxicity caused a significant increase (P < 0.001) in calcium accumulation in strips isolated from rat diaphragms. Treatment of rats having received MCT with Indapamide reduced calcium uptake by diaphragmatic strips to levels that are not significantly different from the control (P > 0.05). Treatment with Indapamide alone did not elicit any change in calcium accumulation in the diaphragmatic strips. Treatment of the animals with MCT, Indapamide or both did not produce any significant change (P > 0.05) in the cell volume of the diaphragmatic strips. Pulmonary hypertension increased calcium uptake by the muscle cells in the rat diaphragm which may alter diaphragmatic contractility; an effect that was prevented by Indapamide.

Animals↗
PubMed2004

Surfactant use for neonatal lung injury: beyond respiratory distress syndrome.

Surfactant has led to a significant reduction in neonatal mortality for premature infants with lung immaturity and respiratory distress. However, surfactant therapy has been shown to be effective in the treatment of a number of other neonatal respiratory disorders and the evidence for surfactant use in such circumstances is presented. Meconium aspiration is characterised by severe atelectasis, the influx of neutrophils, edema, and hyaline membranes, with decreased levels of SP-A and SP-B and the large aggregate fraction of lung surfactant, and altered surfactant surface morphology. Meconium contains cholesterol, free fatty acids and bilirubin all of which can interfere with surfactant function in a dose-dependent fashion. Providing larger amounts of surfactant can overcome some of this inhibition. Animal models of meconium aspiration treated with surfactant have improved histology, lung mechanics and gas exchange. Studies in human infants with meconium aspiration have found elevated concentrations of total protein, albumin, and membrane-derived phospholipid in lung lavage fluid, and haemorrhagic pulmonary edema. Clinical studies in such neonates have reported improved gas exchange and clinical outcomes following surfactant treatment. More recently surfactant lavage has been shown to be a potentially efficacious therapy for such infants. The inflammatory exudate containing plasma proteins and cytokines which accompanies neonatal pneumonia may inactivate surfactant. Surfactant treatment given to animals following the tracheal instillation of group B Streptococcal resulted in significantly less bacterial growth and improved lung function. Small clinical experiences have demonstrated the benefit of surfactant to infants with pneumonia/sepsis. Pulmonary haemorrhage, which some consider a complication of surfactant therapy, has also been effectively managed using surfactant instillation. The hemoglobin and red blood cell lipids may act to inhibit natural surfactant and treatment with surfactant has been shown to improve outcome for infants with pulmonary haemorrhage. Animal models of congenital diaphragmatic hernia (CDH) have hypoplastic lungs with evidence of decreased lamellar bodies in their type II pneumocytes and resultant surfactant deficiency, and respond to surfactant replacement with improved gas exchange and lung mechanics. The lungs of human infants with CDH contain less phospholipids and phosphatidylcholine per milligram of DNA than control infants. Case reports have reported a benefit of surfactant for infants with CDH. In the near-term infants with severe respiratory distress, surfactant is one of the therapies along with inhaled nitric oxide and high frequency ventilations, that have resulted in improved outcomes. Surfactant treatment may be of significant benefit in newborn infants with respiratory compromise secondary to a number of insults, and further prospective evidence of its efficacy in such disorders is needed.

Blood Proteins↗
PubMed1978

Congenital central hypoventilation syndrome: a pathologic study of the neuromuscular system.

An infant with congenital central hypoventilation was managed by bilateral phrenic nerve pacing for 3 months. He died at 8 months of age, following 19 days of continuous bilateral pacing necessitated by the eventual loss of voluntary as well as autonomic ventilatory control. The phrenic nerves showed axonal dystrophy at the site of electrode implantation and more severe distal degeneration. Focal neurogenic atrophy was seen in the diaphragmatic muscle. These changes were attributed to electrical injury resulting from the period of continuous pacing. The most significant neuropathologic finding was a mild generalized decrease in the density of neurons and myelinated nerve fibers in the respiratory centers of the medulla. These morphologic abnormalities were attributed to a sublethal intrauterine lesion that would be the first example of a morphologic correlation with the functional abnormality in congenital central hypoventilation.

Brain↗
PubMed2003

Respiratory muscle weakness and anorexia nervosa.

BACKGROUND: Nutritional recovery in anorexia nervosa (AN) is associated with improved exercise tolerance. METHOD: We describe the investigation of a male with AN. Despite nutritional recovery, he complained of impaired exercise tolerance. RESULTS: Respiratory muscle weakness was demonstrated as the cause of the impaired exercise tolerance. DISCUSSION: Weakness of the muscles of respiration results from prolonged malnutrition. The diaphragmatic muscle may be slower to recover than other muscles. This can cause impaired exercise tolerance due to shortness of breath on exertion, despite nutritional recovery.

Anorexia Nervosa↗
PubMed1994

Type III posterior urethral valves: presentation and management.

The clinical and radiographic presentation of infants with type III posterior urethral valves help to distinguish them from patients with the more common type I valves. The diaphragmatic valvular obstruction may make catheterization impossible. Percutaneous cystography can confirm the diagnosis and allow for short-term decompression. The presence of smooth-walled bladders with narrow posterior urethras is unique to type III valves but is not always present. Type III valves present within a spectrum of clinical severity; however, the majority involve significant renal impairment. The prognosis for survival and renal function appears poorer for patients with type III valves than for those with type I valves.

Child, Preschool↗
PubMed1987

Pathological changes in the vagus nerve in diabetes and chronic alcoholism.

The pathological changes in the vagus nerve removed at necropsy have been studied in patients with chronic alcoholism and diabetes. Morphometric studies on myelinated fibres were performed on the nerve at mid-cervical, lung hilum and diaphragmatic levels. In two insulin-dependent diabetics the density of myelinated fibres was below the lower limit of the control range at all levels. In all the diabetic and chronic alcoholic subjects there was significant reduction in the density of myelinated fibres at the most distal level in the nerve. The degenerative changes in the nerve are consistent with the findings of abnormal vagal function in diabetics and chronic alcoholics.

Adult↗
PubMed1997

Right phrenic nerve palsy as a complication of indwelling central venous catheters.

Five cases are reported of patients who developed a raised right hemidiaphragm while an indwelling central venous catheter was in situ. The patients were being treated with protracted venous infusions of chemotherapy for colorectal carcinoma. All five patients had a chest radiograph following insertion of the Hickman line which showed normal diaphragmatic positions. A mean of 93 days later (range 55-134 days) elevation of the right hemidiaphragm was noted in these patients on repeat chest radiographs. Two of the patients had a right phrenic nerve palsy demonstrated by magnetic stimulation of the nerve. The remaining three patients had paradoxical motion of the right hemidiaphragm on sonography, but were unable to undergo studies of phrenic nerve function before death from metastatic disease. It is suggested that right phrenic nerve palsy is a late complication of an indwelling central venous catheter.

Aged↗
PubMed1998

Regulation of nitric oxide production in response to skeletal muscle activation.

Nitric oxide (NO) is synthesized in normal muscle fibers by the neuronal (nNOS) and the endothelial (ecNOS) isoforms of nitric oxide synthase (NOS). NO contributes to the regulation of several processes such as excitation-contraction coupling and mitochondrial respiration. We assessed in this study whether NO production is regulated in response to an acute increase in muscle activation. Three groups of anesthetized, tracheostomized, spontaneously breathing rats were examined after an experimental period of 3 h. Group 1 served as a control (no loading), whereas groups 2 and 3 were exposed to moderate and severe inspiratory resistive loads, respectively, which elicited tracheal pressures of 30 and 70% of maximum, respectively. Ventilatory (diaphragm, intercostal, and transverse abdominis) and limb (gastrocnemius) muscles were excised at the end of the experimental period and examined for NOS activity and NOS protein expression. Neither submaximal nor maximum tracheal pressures were altered after 3 h of resistive loading. Diaphragmatic and intercostal muscle NOS activities declined significantly in response to moderate and severe loading, whereas those of transverse abdominis and gastrocnemius muscles remained unchanged. On the other hand, resistive loading had no significant effect on ventilatory and limb muscle NOS isoform expression. We propose that a contraction-induced decline in muscle NOS activity represents a compensatory mechanism through which muscle contractility and mitochondrial function are protected from the inhibitory influence of NO.

Animals↗
PubMed2005

Effects of 8-week, interval-based inspiratory muscle training and breathing retraining in patients with generalized myasthenia gravis.

STUDY OBJECTIVE: To assess the effect of interval-based inspiratory muscle training (IMT) combined with breathing retraining (BR) in patients with generalized myasthenia gravis (MG) in a partial home program. DESIGN: A randomized controlled trial with blinding of outcome assessment. SETTING: A secondary-care respiratory clinic. PATIENTS: Twenty-seven patients with generalized MG were randomized to a control group or a training group. INTERVENTIONS: The training group underwent interval-based IMT associated with BR (diaphragmatic breathing [DB] and pursed-lips breathing [PLB]) three times a week for 8 weeks. The sessions included 10 min each of DB, interval-based IMT, and PLB. Interval-based IMT consisted of training series interspersed with recovery time. The threshold load was increased from 20 to 60% of maximal inspiratory pressure (P(Imax)) over the 8 weeks. MEASUREMENTS AND RESULTS: Lung function, respiratory pattern, respiratory muscle strength, respiratory endurance, and thoracic mobility were measured before and after the 8 weeks. The training group improved significantly compared to control group in P(Imax) (p = 0.001), maximal expiratory pressure (P(Emax)) [p = 0.01], respiratory rate (RR)/tidal volume (V(T)) ratio (p = 0.05), and upper chest wall expansion (p = 0.02) and reduction (p = 0.04). Significant differences were seen in the training group compared to baseline P(Imax) (p = 0.001), P(Emax) (p = 0.01), maximal voluntary ventilation (p = 0.02), RR/V(T) ratio (p = 0.003), Vt (p = 0.02), RR (p = 0.01), total time of RR (p = 0.01), and upper chest wall expansion (p = 0.005) and reduction (p = 0.005). No significant improvement was seen in lower chest wall or lung function. CONCLUSIONS: The partial home program of interval-based IMT associated with BR is feasible and effective in patients with generalized MG. Improvements in respiratory muscle strength, chest wall mobility, respiratory pattern, and respiratory endurance were observed.

Adult↗
PubMed1992

Radiotherapy of malignant subdiaphragmatic implants in advanced ovarian carcinoma: a new technique.

We report the development of a new technique using remote afterloading intraoperative radiation therapy to deliver a tumoricidal dose to diaphragmatic tumor implants. A multi-positional lucite applicator was designed based on anatomic studies of the diaphragmatic surface to accommodate a high dose rate iridium source in a series of needles placed 1.5 cm apart. The applicator curvature can vary from planar to full accommodation of the diaphragmatic surface with a constant source to surface distance of 0.5 cm. The applicator has been piloted in three patients with ovarian carcinoma with residual subdiaphragmatic disease found at second look laparotomy, to deliver a dose of 1,500 to 2,000 cGy at 0.5 cm. Tolerance of the diaphragm and hepatic surface has been excellent. There were no postoperative complications and no deterioration in liver function studies. The additional postoperative external beam irradiation directed with the aid of surgically placed clips and gated to respiratory movements permits achievement of a tumoricidal dose while limiting the treated volume and related toxicities.

Brachytherapy↗
PubMed2006

Spontaneous recovery of diaphragmatic strength in unilateral diaphragmatic paralysis.

The aim of the present study was to evaluate diaphragmatic strength in patients with unilateral diaphragmatic paralysis and to determine whether patients with recent diaphragm paralysis develop lower inspiratory pressure than patients with longstanding diaphragmatic paralysis. Twenty patients (16 men and 4 women, 62+/-12 years) and six control subjects were included (4 men and 2 women, 53+/-15 years) in the study. Esophageal pressure during sharp sniff (Pes,sniff), bilateral cervical phrenic nerve magnetic stimulation (Pes,cms) and unilateral phrenic nerve stimulation (Pes,ums) (in nine patients) were measured. Sixteen patients presented right diaphragmatic paralysis and four, left diaphragmatic paralysis. Pes,sniff was higher in control subjects than in patients with diaphragmatic paralysis (respectively 110+/-22 cmH2O and 82+/-24 cmH2O, P<0.05). There was no difference in Pes,cms between patients with diaphragmatic paralysis and control subjects (14+/-7 cmH2O vs. 16+/-4 cmH2O; ns). Pes,ums after stimulation of the affected phrenic nerve was less than 4 cmH2O, was 8+/-2 cmH2O after stimulation of the intact phrenic nerve and was correlated to Pes,cms (R=0.87, P<0.01). There was a positive correlation between Pes,cms, Pes,ums of the intact hemidiaphragm, Pes,sniff and the time from the onset of symptoms and the diaphragmatic explorations (respectively R=0.86, P<0.0001; R=0.72, P<0.05; R=0.48, P<0.05). In conclusion, diaphragmatic strength after unilateral diaphragmatic paralysis seems to improve with time.

Adolescent↗
PubMed1995

A comprehensive electrophysiological evaluation of phrenic nerve injury related to open-heart surgery.

A prospective electrophysiological study of phrenic nerve was performed in 59 subjects undergoing open-heart surgery. The nerve was stimulated percutaneously at the neck and the diaphragmatic response was recorded with surface electrodes placed over the 8th intercostal space. The latency, amplitude, duration and area of the evoked response were measured before and after the operation. Post-operatively no response was elicited in 2 patients bilaterally, in 5 from the left and in 2 from the right. Comparison of the post-operative with the pre-operative group values in the remaining subjects showed that the amplitude and area of the left phrenic were lower in the post-operative study, indicating that some of the nerve fibres were not conducting. There were no statistically significant differences between pre and post-operative values of latency or duration on the left or any of the parameters on the right. Our findings suggest that the amplitude and area of the diaphragmatic response are more sensitive than latency in detecting phrenic nerve paresis associated with open-heart surgery.

Aged↗
PubMed1988

Respiratory muscle weakness associated with cerebellar atrophy.

Transdiaphragmatic pressures were measured in 3 patients with cerebellar atrophy. Recordings were made during 3 types of voluntary maneuver--maximal sniffs, full inspirations, and maximal static inspiratory efforts, and during bilateral supramaximal phrenic nerve stimulation at 1 Hz. Although diaphragmatic weakness was demonstrated during the voluntary maneuvers, transdiaphragmatic pressures recorded during phrenic nerve stimulation were normal. These findings indicate that diaphragmatic dysfunction, probably caused by ataxia during voluntary maneuvers, may occur in association with cerebellar atrophy. In the presence of diaphragmatic weakness, normal values of transdiaphragmatic pressure during phrenic nerve stimulation may suggest an upper motor neuron lesion affecting the diaphragm.

Adult↗
PubMed1995

Diaphragm levels as determinants of P axis in restrictive vs obstructive pulmonary disease.

BACKGROUND AND OBJECTIVE: Verticalized P axes in adults with obstructive lung disease have long been appreciated as characteristic of emphysema. After demonstrating P axes in restrictive lung disease to have a significantly different orientation (intermediate to horizontal), it was hypothesized that opposite effects on diaphragm level by obstructive disease (low diaphragm) and by restrictive disease (high diaphragm) could explain the axis differences, because the right atrium is attached via the inferior vena cava and adjacent pericardium to the right leaf of the diaphragm. METHODS: Electrocardiograms and chest radiographs were analyzed independently in a new series of 20 consecutive patients with purely obstructive and 19 consecutive patients with purely restrictive pulmonary disease. P axes were calculated to the nearest 5 degrees and grouped as vertical (+65 degrees to +90 degrees), intermediate (+40 degrees to +60 degrees), and horizontal (< +50 degrees). Chest radiographs established the right diaphragmatic level by posterior rib number or interspace with interspaces designated as "0.5" plus the number of the rib above. RESULTS: P axes for obstructive vs restrictive disease were different (p < 0.001) as in our previous investigation. In the present series, 19 of 20 electrocardiograms in patients with obstructive disease had vertical P axes between +70 degrees and +90 degrees; in 11 of 19 patients with restrictive disease, P axes were less than +40 degrees (horizontal); 6 were between +40 degrees and +60 degrees (intermediate); and only 2 were vertical. Diaphragm levels were between rib/interspace numbers 10.5 and 12.5 in all patients with obstructive disease. Diaphragm levels among patients with restrictive disease were higher and, like their P axes, more widely distributed: 10 of 19 between rib levels 8.0 and 9.5; only 4 at 10.5 or lower. Thus, vertical P axes corresponded to low (rib/interspace 10.5 to 12.5) and intermediate to horizontal P axes with higher (8.0 to 11.0 rib) diaphragm levels (p < 0.001). CONCLUSION: Because the separate P-axis distributions in restrictive and obstructive lung disease parallel the separate diaphragm levels and because the right atrium is necessarily carried by attachments to the right diaphragmatic leaf, it is likely that the consequent positional effects on the right atrium contribute to or cause the significantly different P-axis orientations in restrictive and obstructive pulmonary disease.

Atrial Function↗
PubMed1989

[2 cases of bilateral diaphragmatic paralysis].

Bilateral diaphragmatic paralysis is characterized by severe dyspnea in decubitus, with or without known respiratory or cardiac disorders. In both patients clinical diagnosis was confirmed by measuring the transdiaphragmatic pressure which was approximately zero. The first patient, previous to the clinical onset, had an episode of gastroenteritis and later developed a pneumonia; in the second patient, clinical manifestations started after neck surgery and both the clinical and functional disorders recovered within the following eight months.

Aged↗
PubMed1989

[A pathologic study of the vagus nerves in diabetes mellitus].

A systematic morphometric examination at different levels of the vagus nerves obtained at autopsy in 4 control subjects and 3 diabetics was carried out. Morphometric studies on myelinated fibres were performed on the nerve at mid-cervical, lung hilum and diaphragmatic levels. In 2 insulin-dependent diabetics the density of myelinated fibres was below the lower limit of the control range at all levels. In all the diabetic subjects there was significant reduction in the density of fibres at the most distal level in the nerves. The teased fibre studies showed predominantly changes of axonal degeneration. They are consistent with the findings of abnormal vagal function in diabetics.

Aged↗
PubMed1991

Ventilatory effects of medical antishock trousers in healthy volunteers.

The ventilatory effects of medical antishock trousers (MAST) were investigated using 10 healthy volunteers. Use of the MAST (60-80 mm Hg) decreased forced expiratory volume (-8% +/- 4%, p less than 0.01), vital capacity (-8% +/- 5%, p less than 0.01), and functional residual capacity (-12% +/- 6%, p less than 0.01) and induced a significant decrease in tidal volume (-30% +/- 17%, p less than 0.05), but minute ventilation was unmodified because of a concomitant increase in respiratory rate (+17% +/- 8%, p less than 0.001). The MAST modified the breathing pattern: the abdominal contribution to ventilation was markedly decreased (-57% +/- 22%, p less than 0.001), suggesting a decrease in the diaphragmatic contribution to ventilation. The MAST increased both the end-expiratory (+131% +/- 115%, p less than 0.01) and inspiratory variation (delta Pgas: +42% +/- 40%, p less than 0.05) of gastric pressure, whereas the end-expiratory and inspiratory variation of esophageal pressure remained unchanged. Because of a higher delta Pgas, the dynamic compliance of the abdominal compartment markedly fell (-77% +/- 10%, p less than 0.001). Transdiaphragmatic pressure (Pdi: +28% +/- 30%, p less than 0.05) significantly increased and the pressure-time index of the diaphragm significantly increased (+32% +/- 32%, p less than 0.05) after inflation of the MAST, suggesting an increase in the diaphragmatic cost of breathing. Inspiratory activity of the parasternal intercostal muscles significantly increased after the MAST was inflated. Computerized tomography showed that the MAST induced a cephalad shift of the diaphragm, which reduced pulmonary height.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗