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Results for “Diaphragmatic function”

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At least 127 records · Page 7Linked to original sources

PubMed1990

Abnormal pulmonary function associated with diaphragmatic pleural plaques due to exposure to asbestos.

Pulmonary function was measured in 79 men with diaphragmatic pleural plaques (DPP) as the only abnormality characteristic of asbestos disease on chest radiographs. They were selected from 4572 construction and shipyard workers exposed to asbestos. Abnormalities of pulmonary function in 21 non-smokers and 43 current smokers were compared with referent values adjusted for height, age, and duration of cigarette smoking. In the non-smokers, flows (FEV1) FEF75-85 and FEV1/FVC) were reduced and TGV and RV/TGV were raised. Current smokers had similar significant reductions. Thus by contrast with some current opinion that plaques are "an index only of past asbestos exposure," workers with plaques, even limited to the diaphragm, have functional impairment typical of pulmonary asbestosis. This suggests that they have pulmonary asbestosis, which is below the threshold of radiographic recognition.

Aged↗

PubMed1994

Critical appraisal of pressure-frequency relation for estimation of diaphragm function in conscious calves.

A method yielding functional diaphragmatic variables in conscious animals is crucially needed to determine whether concepts and conclusions drawn from deeply anesthetized, highly instrumented clinically normal animals can be extrapolated to patients. Transdiaphragmatic pressure (Pdi) was, therefore, measured in 20 conscious calves during supramaximal transvenous bilateral stimulations of the phrenic nerves (pulse duration, 0.2 milliseconds; pulse frequency, 1, 10, 20, 30, 40, 70, and 100 Hz). Constancy of phrenic activation and precontraction length and geometry was ensured by respectively monitoring the amplitudes of right and left mass action potentials and triggering each activation train at end-expiratory lung volume against an occluded airway. Repeated phrenic activation and pressure recording procedures were well tolerated, safe, specific, and able to achieve constant and symmetric diaphragmatic tetanic contractions for prolonged periods. The Pdi increased with frequency of stimulation, so that, at 10, 20, 40, and 70 Hz, the mean +/- SD generated Pdi was 33 +/- 5, 65 +/- 8, 82 +/- 6, and 94 +/- 6% of Pdi at 100 Hz, respectively. The general shape of the Pdi-frequency relation and the absolute values of the generated Pdi were reproducible at 10-hour intervals despite CO2- or resistor-induced substantial changes in breathing pattern. It is concluded that this experimental model provides a reliable assessment of diaphragm function in conscious animals and can be used to study diaphragmatic contractility.

Action Potentials↗

PubMed1992

Plication of the diaphragm for unilateral eventration or paralysis.

Unilateral diaphragmatic paralysis and eventration have the same appearance and provoke the same disturbances. Diaphragmatic plication is intended to decrease lung compression, to make the thoracic base and mediastinum more stable, and to strengthen the respiratory action of intercostal, perithoracic, and abdominal muscles: 13 infants and children were operated upon, 7 in acute respiratory failure and ventilator-dependent, 4 in chronic respiratory failure; 11 adults were operated upon, 8 with respiratory and 3 with digestive symptoms. Four infants who had been operated upon before the 10th day of life died: 3 from associated diseases and 1 from a lung infection. The 9 survivors have been followed up for a mean period of 6.6 years. All were asymptomatic and the position of the plicated diaphragm was maintained. The 11 adults have been followed up for a mean period of 8.5 years. Nine were asymptomatic; in 1, dyspnea had decreased; in 1, reflux persisted and was surgically cured. In 5 adults, the respiratory tests showed a mean amelioration of 20% of vital capacity and 15% of forced expiratory volume in 1 s. In infants, the prognosis depends on associated malformations and on the condition of the lung. Plication should be performed after 2 weeks on a ventilator. In older children and adults, plication is justified when the anomaly produces symptoms (malignancy excluded). Plication is simple, efficient, and durable, but there is no indication of subsequent diaphragmatic function: its effects on respiratory mechanics are probably indirect.

Adolescent↗

PubMed1993

Thoracic epidural anesthesia increases diaphragmatic shortening after thoracotomy in the awake lamb.

BACKGROUND: Prolonged inhibition of diaphragmatic function occurs after thoracic and upper abdominal surgery. It was hypothesized that thoracic epidural anesthesia on the day after a thoracotomy could block inhibitory neural pathways and increase the shortening of costal and crural diaphragmatic segments. METHODS: Pairs of sonomicrometer crystals were implanted into the costal and crural regions of the diaphragm through a right lateral thoracotomy in 14 30-kg, 4-5-month-old lambs. One day after surgery, a thoracic epidural catheter was placed at the T8-T9 level. Regional diaphragmatic shortening normalized to end-expiratory length (%LFRC), was measured by sonomicrometry in these awake lambs. Changes in gastric (delta Pgas), esophageal (delta Pes), and transdiaphragmatic (delta Pdi) pressures were measured with transnasal balloon catheters. End-tidal carbon dioxide (FETCO2), costal and crural electromyogram (Edi), and tidal volume (VT) were measured. Inductance plethysmography was used in four lambs to assess relative contributions of the rib cage and abdomen to VT. Control values were obtained during quiet breathing and while rebreathing at up to 10% FETCO2. To block thoracic dermatomes, 1% or 2% lidocaine was injected through the epidural catheter. Measurements were repeated after each lidocaine injection. RESULTS: There was no change of resting length with 1% lidocaine; costal resting length increased by 22% with 2% lidocaine. After 2% lidocaine, costal %LFRC increased from control both during quiet breathing (8.7 +/- 0.7 to 18.1 +/- 1, mean +/- SEM%) and at FETCO2 10% (22.1 +/- 2 to 33.7 +/- 3%). VT during quiet breathing was unchanged after 1% lidocaine but increased from 235 +/- 16 to 283 +/- 28 ml after 2% lidocaine. At 10% FETCO2, delta Pdi was unchanged after 1% lidocaine and decreased from 36.5 +/- 4.3 to 26.3 +/- 4.9 cmH2O after 2% lidocaine. Regional delta Edi was unchanged with both 1% and 2% lidocaine at rest and during carbon dioxide rebreathing. Plethysmography in three lambs showed a reduction in rib cage contribution to tidal volume with 2% lidocaine during quiet breathing. CONCLUSIONS: Improved postoperative tidal volume and diaphragmatic shortening after thoracic epidural blockade may be due to changes of chest wall conformation and resting length and a shift of the workload of breathing from the rib cage to the diaphragm caused by intercostal muscle paralysis.

Anesthesia, Epidural↗

PubMed1995

Application of a cervical stimulating apparatus for bilateral transcutaneous phrenic nerve stimulation.

Transcutaneous bilateral phrenic nerve stimulation (tPNS) is frequently used to assess diaphragmatic function in humans. Commonly, stimulation is performed with hand-held electrodes; however, these are unsuitable for studies requiring repeated PNS and where recruitment of rib cage and neck muscles may shift the probes in relation to the nerves. In this study we describe the design of a cervical neck brace and electrode probes that maintain stimulating electrodes in constant position relative to the phrenic nerves and facilitates studies requiring repeated maximal PNS. The effectiveness of the apparatus was examined by 1) reviewing the reproducibility of the transdiaphragmatic pressure response to 0.1 ms tPNS (PdiT) at relaxed functional residual capacity in four subjects studied on 25 +/- 8 (SD) occasions (> or = 24 h apart) over a 4-yr period, and 2) measuring peak-to-peak amplitude of the left and right diaphragmatic compound muscle action potentials (surface electrodes) during two prolonged studies (38 +/- 9 min) in each subject, when tPNS was performed during repeated submaximal and maximal inspiratory efforts. PdiT was reproducible in each subject when measured repeatedly within a single study [coefficient of variation (CV) of 3.8 +/- 0.8%] and over separate days (CV of 11.5 +/- 3.5%). The peak-to-peak amplitudes of the left and right compound muscle action potentials were also reproducible (CV of 8.4 +/- 4.3 and 8.4 +/- 2.9%, respectively) and independent of the degree of effort. The apparatus appears effective for the maintenance of maximal stimulation under varied conditions for long periods and provides reproducible measurements of PdiT both within and between studies.

Action Potentials↗

PubMed1983

Diaphragm dysfunction induced by upper abdominal surgery. Role of postoperative pain.

The effects of upper abdominal surgery on diaphragmatic function were studied in 5 patients. During quiet tidal breathing, the volume displacement of the abdomen within the tidal volume (Vab/Vt) and the ratio of abdominal and transdiaphragmatic pressure changes (delta Pab/delta Pdi), taken as an index of the diaphragmatic contribution to the breathing process, decreased significantly on the first postoperative day (p less than 0.001); in 2 patients, a cephalad paradoxical motion of the diaphragm during inspiration was observed. Diaphragmatic dysfunction also occurred during maximal inspiratory efforts as shown by the significant fall in maximal static transdiaphragmatic pressure (Pdimax) and cephalocaudal diaphragmatic displacement on the first (p less than 0.001) and third (p less than 0.001) postoperative days. On the first postoperative day, opiate epidural analgesia did not modify Vab/VT, delta Pab/delta Pdi, and Pdimax. These parameters spontaneously returned towards control values on the seventh postoperative day. We conclude that upper abdominal surgery induces a marked diaphragmatic dysfunction lasting about 1 wk and that it is not suppressed by postoperative pain relief. The mechanism of this dysfunction remains to be determined. It may be the main cause of the postoperative pulmonary restrictive pattern.

Abdomen↗

PubMed1992

Hemidiaphragmatic paresis during interscalene brachial plexus block: effects on pulmonary function and chest wall mechanics.

We studied the effects of unilateral hemidiaphragmatic paresis caused by interscalene brachial plexus block on routine pulmonary function in eight patients. In an additional four patients, we studied changes in chest wall motion during interscalene block anesthesia by chest wall magnetometry. Ipsilateral hemidiaphragmatic paresis, as diagnosed by ultrasonography, developed in all patients within 5 min of interscalene injection of 45 mL of 1.5% mepivacaine with added epinephrine and bicarbonate. Large decreases in all pulmonary function variables were measured in every patient. Forced vital capacity and forced expiratory volume at 1 s decreased 27% +/- 4.3% and 26.4% +/- 6.8%, respectively (P = 0.0001). Peak expiratory and maximum midexpiratory flow rates were also significantly reduced. Interscalene block caused changes in pulmonary function and chest wall mechanical motion that were similar to those published in previous studies on patients with hemidiaphragmatic paresis of pathological or surgical etiology. Interscalene block probably should not be performed in patients who are dependent on intact diaphragmatic function and in those patients unable to tolerate a 25% reduction in pulmonary function.

Adult↗

PubMed1993

Mammalian locomotor-respiratory integration: implications for diaphragmatic and pulmonary design.

Diaphragmatic function and intrapulmonary respiratory flow in running mammals were found to differ substantially from the corresponding conditions known in resting mammals. In trotting dogs, orbital oscillations of the diaphragm were driven by inertial displacements of the viscera induced by locomotion. In turn, oscillations of the visceral mass drove pulmonary ventilation independent of diaphragmatic contractions, which primarily served to modulate visceral kinetics. Visceral displacements and loading of the anterior chest wall by the forelimbs are among the factors that contribute to an asynchronous ventilation of the lungs and interlobar gas recycling. Basic features of mammalian respiratory design, including the structure of the diaphragm and lobation of the lungs, appear to reflect the mechanical requirements of locomotor-respiratory integration.

Animals↗

PubMed1999

In normal subjects bracing impairs the function of the inspiratory muscles.

Normal subjects can increase their capacity to sustain hyperpnoea by bracing their arms on fixed objects, a procedure which is also known to reduce dyspnoea in patients with chronic obstructive pulmonary disease (COPD). In the present study, it was tested whether bracing per se could improve the function of the diaphragm. The effect of bracing on diaphragm function was studied in six normal subjects by recording changes in oesophageal (delta Poes) and transdiaphragmatic (delta Pdi) pressure during inspiratory capacity (IC) manoeuvres in the seated and upright postures, and in the seated posture, also during bilateral phrenic nerve stimulation (BPNS) at functional residual capacity (FRC). The pattern of ribcage motion and deformation associated with bracing and with diaphragm contraction was also evaluated using inductance plethysmography and magnetometers. Bracing increased FRC by >300 mL and reduced IC by approximately 200 mL, in both postures. Delta Pdi during BPNS decreased on average by 15% indicating an impaired diaphragmatic function. The ribcage was deformed with bracing and was more distortable during BPNS. In conclusion, in normal subjects, bracing impairs the function of the inspiratory muscles and reduces ribcage stability. These negative effects cannot explain the improved capacity to sustain hyperpnoea when the arms are braced.

Adult↗

PubMed1976

Injuries to the phrenic nerve resulting in diaphragmatic paralysis with special reference to stretch trauma.

Traumatic interruption of the phrenic nerve causing diaphragmatic paralysis occurs much more commonly than realized. Patients present with symptoms referable to the respiratory, gastrointestinal, or cardiovascular systems as a result of anatomic displacement of the respective organ (eventration). Symptoms often occur shortly after the injury but may be delayed for many years; consequently, prolonged follow-up of these patients is essential. If patients are symptomatic after trauma, judicious observation is dictated, since many will experience gradual return of normal diaphragmatic function over the succeeding six to twelve months. In those who remain significantly symptomatic, thoracotomy and imbrication of the eventration is a simple and effective surgical procedure.

Adult↗

PubMedDate not supplied

Rod myopathy with extensive systemic and respiratory muscular involvement.

A patient with both muscle weakness and progressively degenerating respiratory function became increasingly less responsive to therapeutic intervention. The diagnosis of the muscle disease was made through biopsy samples and confirmed as rod myopathy. Through autopsy samples, the patient was found to have had extensive centriacinar emphysema and widespread involvement of rod disease in the skeletal muscles. The most involved of the muscles sampled (anterior tibial, brachioradialis, rectus femoris, psoas, diaphragm, biceps) was the diaphragm. While the influence on diaphragmatic function has been reported in the juvenile form of rod disease, this is the first known report of the extensiveness of involvement in adult-onset disease. The diseased state of the diaphragm was appreciated as a contributing factor to the respiratory insufficiency.

Adult↗

PubMed1980

The role of respiratory muscles in the hyperinflation of bronchial asthma.

To examine the mechanism of hyperinflation in bronchial asthma we studied lung and chest wall mechanics in 7 asymptomatic patients in whom progressive bronchoconstriction was induced by doubling the amount of inhaled aerosolized histamine. An increase in pulmonary resistance (RL) from 2.5 +/- 0.3 cmH2O . 1-1 . s (mean, +/- 1 SE) to 12.3 +/- 0.9 cmH2 was associated with a linear increase in functional residual capacity (FRC) up to 74.7 +/- 1.7% of control total lung capacity (TLCc). The mean regression coefficient was 2.3% TLCc . cmH2O-1 . 1 . s-1. At each level of hyperinflation the most positive expiratory pleural pressures measured during spontaneous breathing were generally less than the predicted chest wall relaxation pressures, indicating persistent inspiratory muscle contraction throughout expiration. This was predominantly due to inspiratory intercostal and accessory muscle activity, because measurements of transdiaphragmatic pressure indicated complete diaphragmatic relaxation early in expiration. Recruitment of abdominal muscles during expiration, inferred from measurements of gastric pressure (Pg) and abdominal antero-posterior (A-P) diameter, was progressively more apparent with increasing bronchoconstriction. We concluded that the increase in FRC in induced asthma is substantially influenced by persistent inspiratory intercostal and accessory muscle activity during expiration. Concomitant abdominal muscle recruitment results in a chest wall configuration that tends to optimize diaphragmatic function.

Abdomen↗

PubMed1993

Needle electromyography of the diaphragm: a new technique.

Electrodiagnostic evaluation of diaphragmatic function has consisted of phrenic nerve stimulation and surface or esophageal recordings of the electrical activity of the diaphragm. Needle electromyography of the diaphragm has rarely been reported because of the perceived danger of this procedure. We describe a new technique for needle electromyography of the diaphragm. An EMG electrode is placed in the costal insertion of the diaphragm under the 8th, 9th, or 10th rib cartilage, distant from the major vessels, pleura, lungs, and abdominal viscera. Diaphragmatic denervation was found in 42 of 81 patients using this method. There were no complications related to the procedure. Needle electromyography of the diaphragm provides important information in the diagnosis and management of respiratory dysfunction.

Adult↗

PubMed1981

Aminophylline improves diaphragmatic contractility.

In an attempt to explain the clinical efficacy of aminophylline, we studied its effect on diaphragmatic function in eight normal subjects. The relation between the electrical activity of the diaphragm and the pressure generated by the diaphragm was assessed during voluntary contractions before and after aminophylline infusion. Aminophylline shifted the electrical activity/pressure curve to the left; the pressure at a given electrical activity increased an average of 15 per cent (P less than 0.001). In four subjects, pressure was also measured during stimulation of the phrenic nerve at various frequencies before and after diaphragmatic fatigue was produced by resistive breathing, with and without aminophylline infusion. Pressure increased after fatigue at all stimulation frequencies with aminophylline, as compared with the pressure after identical fatigue runs at the same stimulation frequencies without aminophylline. The mean plasma aminophylline concentration associated with these responses was 13 +/- 0.9 mg per liter. We conclude that aminophylline improves the diaphragm's contractility and renders it less susceptible to fatigue.

Adult↗

PubMed1998

Assessment of respiratory muscle function and strength.

Measurement of respiratory muscle strength is useful in order to detect respiratory muscle weakness and to quantify its severity. In patients with severe respiratory muscle weakness, vital capacity is reduced but is a non-specific and relatively insensitive measure. Conventionally, inspiratory and expiratory muscle strength has been assessed by maximal inspiratory and expiratory mouth pressures sustained for 1 s (PImax and PEmax) during maximal static manoeuvre against a closed shutter. However, PImax and PEmax are volitional tests, and are poorly reproducible with an average coefficient of variation of 25%. The sniff manoeuvre is natural and probably easier to perform. Sniff pressure, and sniff transdiaphragmatic pressure are more reproducible and useful measure of diaphragmatic strength. Nevertheless, the sniff manoeuvre is also volition-dependent, and submaximal efforts are most likely to occur in patients who are ill or breathless. Non-volitional tests include measurements of twitch oesophageal, gastric and transdiaphragmatic pressure during bilateral electrical and magnetic phrenic nerve stimulation. Electrical phrenic nerve stimulation is technically difficult and is also uncomfortable and painful. Magnetic phrenic nerve stimulation is less painful and transdiaphragmatic pressure is reproducible in normal subjects. It is a relatively easy test that has the potential to become a widely adopted method for the assessment of diaphragm strength. The development of a technique to measure diaphragmatic sound (phonomyogram) during magnetic phrenic nerve stimulation opens the way for noninvasive assessment of diaphragmatic function.

Electric Stimulation↗

PubMed1990

Chest wall motion of infants during spinal anesthesia.

To test the extent to which diaphragmatic contraction moves the rib cage in awake supine infants during quiet breathing, we studied chest wall motion in seven prematurely born infants before and during spinal anesthesia for inguinal hernia repair. Infants were studied at or around term (postconceptional age 43 +/- 8 wk). Spinal anesthesia produced a sensory block at the T2-T4 level, with concomitant motor block at a slightly lower level. This resulted in the loss of most intercostal muscle activity, whereas diaphragmatic function was preserved. Rib cage and abdominal displacements were measured with respiratory inductance plethysmography before and during spinal anesthesia. During the anesthetic, outward inspiratory rib cage motion decreased in six infants (P less than 0.02, paired t test); four of these developed paradoxical inward movement of the rib cage during inspiration. One infant, the most immature in the group, had inward movement of the rib cage both before and during the anesthetic. Abdominal displacements increased during spinal anesthesia in six of seven infants (P less than 0.05), suggesting an increase in diaphragmatic motion. We conclude that, in the group of infants studied, outward rib cage movement during awake tidal breathing requires active, coordinated intercostal muscle activity that is suppressed by spinal anesthesia.

Anesthesia, Spinal↗

PubMed1989

[Diaphragmatic fatigue and its role in the development of respiratory insufficiency and cor pulmonale in COPD].

Diaphragmatic function test was performed at rest and during maximal incremental exercise in six male normal non-smokers (Group A), sixteen male patients with COPD (58 +/- 8 yrs), including 4 with only small airway disorder (B) 6 with mild (C) and 6 with moderate airway obstruction (D) and eight patients with cor pulmonale complicated severe airway obstruction and chronic respiratory failure (E). Maximal transdiaphragmatic pressure (Pdi max) at rest in Group A, B, C, D, E were 13.6 +/- 2.9 kPa, 10.8 +/- 3.1 kPa, 9.9 +/- 3.4 kPa, 6.8 +/- 3.3 kPa and 5.3 +/- 2.5 kPa respectively, the latter two (D and E) being significantly lower than that of the normal control (D, P less than 0.05, E, P less than 0.01). Breathing pattern of the diaphragm at rest was similar to the normal control in all groups except that half of the patients in Group E (4/8) showed diaphragmatic paradoxical motion during inspiration. Ergometer test with incremental workload was performed in all groups except for Group E. During exercise, patients with COPD revealed some extent of diaphragmatic fatigue. All in group D(6/6) and most in group C(4/6) eventually developed inspiratory paradoxical motion of diaphragm before the ventilatory reserve was exhausted.

Aged↗

PubMedDate not supplied

[Contusion ruptures of the ocular capsule along postoperative corneo-limbic scars].

Clinical picture, variants of surgical treatment, and anatomic and functional outcomes of contusion ruptures of the eyeball at the site of postoperative corneolimbic cicatrices are described. Such traumas can occur even 9-10 years after keratotomy. The majority of unfavorable outcomes in such patients are due to retinal and vitreous abnormalities, such as hemophthalmia or detachment of the retina. Ruptures of corneolimbic cicatrices in patients after cataract extraction with or without implantation of intraocular lenses are more frequent during the first months after surgery; an indirect contusion is sufficient to cause them. The incidence of fibrous capsule ruptures does not depend on the localization of the cicatrice and type of suture. Ruptures of cicatrices on artiphakic eyes almost always involve falling of intraocular lenses into the wound. An intact diaphragmatic function of the iris and transparent optic media are prognostically favorable factors in such patients.

Adult↗