SEARCH · PubMed Health

Results for “Diaphragmatic function”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 217 records · Page 12Linked to original sources

PubMed2002

Transient post-traumatic hemidiaphragmatic paralysis in two cats.

A diagnosis of post-traumatic hemidiaphragmatic paralysis was made in two cats. Both cats had a history of trauma and paradoxical inward movement of the abdominal wall at inspiration. Thoracic radiographs were taken at inspiration and expiration. Although the images were suggestive of hemidiaphragmatic paralysis, definitive diagnosis was reached by fluoroscopy in one cat and by ultrasonography in the second. Both cases resolved spontaneously and diaphragmatic function was normal at follow-up.

Animals↗

PubMed1981

Limitations of measurement of transdiaphragmatic pressure in detecting diaphragmatic weakness.

Intrathoracic (oesophageal), intra-abdominal (gastric), and transdiaphragmatic (Pdi) pressures were studied in 20 untrained, healthy subjects during a full inspiration and repeated maximal static inspiratory efforts. The pattern of pressure generation during these two types of respiratory manoeuvre was highly reproducible in each subject. By contrast, it varied over a wide range among individuals. In particular a substantial number of subjects naturally had a strong recruitment of their intercostal and accessory muscles and thus, low Pdi values, during both slowly performed and forceful inspiratory manoeuvres. These observations make it clear that Pdi values, as usually obtained, are commonly open to misinterpretation. For this approach to ensure a reliable assessment of diaphragmatic function and detect diaphragm weakness adequately, it appears essential either to monitor the abdominothoracic configuration or to standardise the pattern of respiratory muscle contraction.

Adult↗

PubMed1993

Effect of aminophylline on respiratory muscle strength after upper abdominal surgery: a double blind study.

BACKGROUND: The effect of aminophylline on maximum respiratory muscle strength in patients undergoing upper abdominal surgery was investigated. METHODS: An open pilot study was performed in which aminophylline was administered continuously for 48 hours after surgery (protocol I). In a second group of subjects aminophylline was given for 24 hours after cholecystectomy in a double blind placebo controlled trial (protocol II). Twelve patients participated in the pilot study (group A) and 25 in protocol II of which 14 received aminophylline (group B) and 11 placebo (control, group C). Respiratory muscle strength was assessed by measuring mouth pressures during maximum static inspiratory and expiratory efforts. Forced expiratory volume in one second (FEV1), forced vital capacity (FVC), vital capacity (VC), inspiratory maximum pressures (PImax), expiratory maximum pressures (PEmax) were measured 24 hours preoperatively, PImax and serum theophylline 24 hours postoperatively, and FEV1, FVC, VC, PImax, PEmax, and serum theophylline 48 hours after surgery. RESULTS: FEV1, FVC, and VC decreased in all groups of patients at +48 hours. PImax fell at +24 hours and +48 hours but this decrease was significantly smaller in the two groups who received aminophylline than in the control group. PEmax showed a decrease at +48 hours but this reduction was similar in all three groups studied, independent of the treatment given. These data suggest that either aminophylline had a protective effect only on the inspiratory muscles or, most probably, that the effect of aminophylline was central, reducing the phrenic nerve inhibition induced by cholecystectomy and thus improving diaphragmatic function. CONCLUSIONS: Upper abdominal surgery decreases inspiratory and expiratory muscle strength and aminophylline has a protective effect only on inspiratory muscle function. This may have important clinical applications in minimising pulmonary complications after cholecystectomy.

Abdomen↗

PubMed1976

Respiratory muscle action inferred from rib cage and abdominal V-P partitioning.

We measured separate volume-pressure (V-P) relationships or rib cage and diaphragm-abdomen in seven human subjects during voluntary relaxation of the respiratory muscles, breathing at rest, during exercise, and rebreathing expired air. Estimates of separate volume displacements of the two parallel chest wall pathways were based on analysis of rib cage and abdominal anteroposterior diameter changes. The pressure developed across each pathway (transthoracic pressure) was partitioned into two serial pressure drops: transdiaphragmatic pressure and transabdominal pressure. We develop the concept that the relationship of volume displacements of structures to pressures developed by the structures during breathing, as compared to the relaxed state, reflects action of respiratory muscles in the structure. We interpret the relationship of rib cage volume displacements to transabdominal pressure (during breathing vs. relaxation) as indicating action of intercostal and accessory muscles only, the separate action of diaphragm on rib cage being measured by transdiaphragmatic pressure. At rest, the diaphragm is the only importantly active respiratory muscle. During increased ventilation activity of other respiratory muscles appears coordinated to assist the optimize diaphragmatic function.

Abdomen↗

PubMed1988

Development of stability of the respiratory system in preterm infants.

Chest wall distortion leads to increased minute volume displacement of the diaphragm (MVDD) and diaphragmatic work (DW) in preterm infants. Lung mechanics, MVDD, and DW were measured at weekly intervals in six preterm infants between 29 and 36 wk postconceptional age. Over the period of study, MVDD and DW decreased significantly, whereas dynamic lung compliance consistently increased. There was no consistent change in the pulmonary ventilation, total pulmonary resistance, the work performed on the lungs, or the change in intraesophageal pressure with tidal breathing. The improvement in the stability of the chest wall, as indicated by the change in these dynamic measurements of diaphragmatic function, parallels the decrease in static chest wall compliance and the clinical course of the resolution of apnea of prematurity.

Airway Resistance↗

PubMed1990

Regional metabolic differences in the rat diaphragm.

This study characterized the biochemical properties of the rat diaphragm by measuring the activities of selected citric acid cycle and glycolytic enzymes. The diaphragm was removed from 10 female Sprague-Dawley rats (180 days old) and dissected into five discrete anatomic regions: crural (region 1), left posterior costal (region 2), left anterior costal (region 3), right anterior costal (region 4), and right posterior costal (region 5). Sections were assayed for total protein concentration and the activities of succinate dehydrogenase (SDH) and lactate dehydrogenase (LDH). The SDH activity in the crural region was approximately 18% lower (P less than 0.05) than that in any costal region. Furthermore, protein concentration was significantly lower (P less than 0.05) in the crural region compared with all costal regions. In contrast, costal regions 2-5 did not significantly differ from each other in protein concentration or SDH activity. LDH activity did not differ significantly (P greater than 0.05) between regions. Finally, the LDH-to-SDH activity ratio was significantly higher (P less than 0.05) in the crural diaphragm compared with all costal regions. We conclude that the crural region of the rat diaphragm is significantly lower in oxidative capacity than all the costal regions. Investigators who use a rodent model to study diaphragmatic function and plasticity should consider the oxidative heterogeneity of the diaphragm when designing experiments.

Animals↗

PubMed1991

Restriction of regional blood flow and diaphragmatic contractility.

We have tested the hypothesis that the diaphragmatic head-to-head arterial anastomosis system should maintain adequate diaphragmatic function even during occlusion of some of its arteries. In six anesthetized open-chest dogs, left phrenic vein blood flow (Qphv) was measured by pulsed Doppler flowmetry. Contractility was measured by sonomicrometry in the left costal and crural diaphragm. The diaphragm was paced for 15 min by continuous bilateral supramaximal phrenic nerve stimulation. In five separate runs the following arteries were occluded at minute 5: 1) left phrenic artery, 2) internal mammary artery (IMA), 3) left phrenic artery and IMA, 4) descending aorta, and 5) descending aorta and IMA. Occlusion was then released at minute 10 of the run. In runs 1-3 there were no changes in contractility in costal or crural diaphragm and no changes in Qphv. However, in runs 4 and 5, Qphv decreased to 55.2 +/- 7.4 and 24.0 +/- 6.5% of control values, respectively. In run 4, percent maximum shortening from functional residual capacity (%LFRC) of the crural diaphragm decreased by 39.1%, while %LFRC of the costal diaphragm increased by 41.4% and abdominal pressure decreased by 47.0%. In run 5, abdominal pressure decreased by 53.5% and %LFRC of the crural and costal diaphragm decreased by 45.5 and 5.8%, respectively. Also relative postocclusion hyperemia was greater in run 5 (64.8%) than in run 4 (40.2%).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Diethylmaleate produces diaphragmatic impairment after resistive breathing.

Formation of oxygen-derived free radicals and activation of the glutathione (GSH) redox cycle has been associated with impaired rat diaphragm performance. Diethylmaleate (DEM) given intraperitoneally irreversibly conjugates with GSH, resulting in marked decreases in tissue concentrations of GSH. We have investigated the effects of acute GSH depletion by DEM on diaphragmatic function during resistive breathing (RB) in the rat. The experimental groups were 1) control, 2) DEM alone, 3) RB, and 4) DEM with RB (DEM + RB). RB was obtained by inspiratory RB until the rats were unable to sustain 70% of maximum airway opening pressure. A portion of the diaphragm was frozen for biochemical assays, and the rest of the diaphragm was prepared for measurement of in vitro contractile properties, including maximum tetanic tension, twitch tension, force-frequency curves, and contraction times. DEM treatment produced a profound depletion of GSH in the DEM and DEM + RB groups. Neither DEM nor RB alone significantly altered diaphragm contractile properties. In DEM + RB rats, however, there was a significant decrease in maximum tetanic tension, twitch tension, and tetanic tension. These data reveal that DEM produced an acute depletion of GSH in the diaphragm without impairment of the muscle in nonstressed rats. In the presence of DEM-induced GSH depletion, RB did result in marked diaphragm impairment. The depletion of GSH and the subsequent impairment in diaphragm contractility after RB suggest that GSH may play an important role in protecting the diaphragm against oxidative stress associated with RB.

Animals↗

PubMedDate not supplied

Salvage of a fetus with congenital high airway obstruction syndrome by ex utero intrapartum treatment (EXIT) procedure.

A fetus with congenital high airway obstruction syndrome (CHAOS) due to complete tracheal atresia was referred at 31 weeks of gestation after 12 weeks of massive hydrops. The fetus was delivered by the ex utero intrapartum treatment procedure allowing sufficient time while on placental support for bronchoscopy to confirm tracheal atresia and tracheostomy to secure the airway. His postnatal course was complicated by severe capillary leak syndrome secondary to hydrops, diaphragmatic paralysis, tracheobronchial malacia, and the need for chronic ventilatory support. The infant's tracheobronchial malacia resolved by 5 months of age and normal diaphragmatic function was restored at 9 months allowing him to be weaned from mechanical ventilation. He underwent tracheal reconstruction at 17 months of age. At follow up at 32 months of age he has a patent airway and is the first long-term survivor with CHAOS.

Adult↗

PubMedDate not supplied

Circumferential cervical spine surgery in an 18-month-old female with traumatic disruption of the odontoid and C3 vertebrae. Case report and review of techniques. Case report and review of techniques.

STUDY DESIGN: A case study of an 18-month-old female with craniovertebral instability and spinal cord compression requiring circumferential stabilization. A review of surgical techniques in upper cervical spine and craniovertebral stabilization for young children is provided. OBJECTIVES: To describe an interesting surgical approach in a young pediatric patient requiring circumferential stability at the craniovertebral junction. BACKGROUND DATA: Craniovertebral instability is problematic in the young pediatric population due to the inability to secure hardware for stabilization. We present an interesting case of spinal cord compression with craniovertebral instability in an 18-month-old female requiring circumferential cervical spine and craniovertebral stabilization. METHODS: The patient presented with acute onset quadriparesis after a fall. Radiographs demonstrated C2-C3 disruption with canal compromise. Magnetic resonance imaging revealed signal changes of the spinal cord at C2-C3. Neurological examination revealed normal muscle volume with strength 1/5 in the upper extremities and 0/5 in the lower extremities. Respirations were normal with normal diaphragmatic function. Cranial nerves were intact. RESULTS: Halo-traction attempted at 0.453 kg induced occipital-atlantal dislocation. The patient underwent anterior corpectomy of C3 and the base of C2 with autologous rib grafts placed from C2 to C4 and macropore as an anterior plating system. Posteriorly the patient had occiput-C3 fusion with a titanium rod and autologous rib grafts bilaterally. Postoperatively the patient regained normal neurological function with circumferential fusion after 4 months in a halo vest. CONCLUSIONS: This case demonstrates the ability to achieve circumferential stabilization in the young pediatric patient. Injuries at the odontoid synchondrosis can be difficult to treat and are only complicated by having to achieve a posterior fusion at the craniovertebral junction. We present a successful case of circumferential fusion and offer a surgical technique to achieve spinal cord decompression and fusion of the upper cervical spine and craniovertebral junction in the young pediatric population.

Accidental Falls↗

PubMed1996

Comparison of cervical magnetic and transcutaneous phrenic nerve stimulation before and after threshold loading.

Brief supramaximal stimulation of the phrenic nerves (twitch) is considered a promising technique to detect diaphragmatic fatigue in humans. However, the most commonly employed methodology (transcutaneous stimulation) is technically difficult. Cervical magnetic stimulation is a recently described technique that is potentially simpler and may obviate some of the problems inherent with transcutaneous stimulation. The purpose of this study was to determine the ability of cervical magnetic stimulation to evaluate diaphragmatic function. Accordingly, we measured transdiaphragmatic pressure (Pdi) during transcutaneous and cervical magnetic stimulation of the phrenic nerves before and after a potentially fatiguing task; inspiratory threshold loading to task failure. During threshold loading, subjects generated approximately 60% of their maximal esophageal pressure with each breath until they could no longer reach the target pressure. At least 10 twitches were obtained during both transcutaneous and magnetic stimulation before and 10, 30, 60, and 120 min after threshold loading. Control twitch Pdi was significantly larger during magnetic stimulation compared with transcutaneous stimulation: 39.3 +/- 3.0 (mean +/- SE) versus 27.4 +/- 2.3 cm H2O, p < 0.0005. This increase in twitch Pdi was solely due to the esophageal component. Following threshold loading, a significant reduction in transcutaneous twitch Pdi was seen in only three of the 10 subjects. Mean transcutaneous twitch Pdi fell only slightly from 27.4 +/- 2.3 during control to 25.1 +/- 2.2 cm H2O at 10 min after loading (p < 0.004). In contrast, magnetic twitch Pdi was significantly reduced in nine of the 10 subjects following threshold loading. Mean magnetic twitch Pdi fell from 39.3 +/- 3.0 during control to 31.1 +/- 3.0 cm H2O at 10 min after loading (p < 0.0001). The average fall in twitch Pdi post-loading (expressed as a percentage of the control value) was significantly greater for magnetic stimulation compared with transcutaneous stimulation: 21.0 +/- 3.1 versus 7.8 +/- 2.9%, p < 0.0001. In summary: (1) in the fresh state, twitch Pdi is larger with magnetic stimulation compared with transcutaneous stimulation, and (2) transcutaneous and cervical magnetic twitch Pdi are affected differently by threshold loading to task failure.

Adult↗

PubMed1976

Diaphragmatic changes in emphysema.

The diaphragms and lungs of 95 men were quantitatively examined at autopsy, and the following observations were made. The area of the whole diaphragm had a significant inverse correlation (r= -0.412, P less than 0.001) with the percentage of the lung occupied by emphysematous lesions. Most of the reduction in the area of the whole diaphragm associated with advanced emphysema occured in the muscular portion; in contrast, the thickness of the diaphragm was not affected by percentage of the lung occupied by emphysematous lesions. Neither body height nor postmortem lung volume had as close a relation to area of the whole diaphragm as did percentage of the lung occupied by emphysematous lesions. The conclusion drawn from these observations is that the diaphragm area reduction associated with emphysema is related to altered thoracic shape, probably diaphragm flattening in particular, and is better described as contracture than as atrophy. It is speculated that these morphologic changes contribute to the altered diaphragmatic function characteristic of chronic obstructive pulmonary disease, and thereby to the ventilatory abnormalities seen in patients with this disorder.

Adult↗

PubMed1985

Effect of abdominal strapping on chest wall mechanics during exercise in patients with severe chronic air-flow obstruction.

We studied the effect of abdominal loading on exercise performance in 7 patients with severe chronic air-flow obstruction (CAO). The patients were exercised to exhaustion on a bicycle ergometer at a work rate equivalent to 80% of their maximal work rate. Three exercise studies were completed in the same afternoon. The first and third were control studies; in the second, the abdomen was strapped with a belt that was secured after the patient had expired below FRC. Neither TLC (p greater than 0.3) nor FRC (p greater than 0.05) were altered by strapping. Exercising with the abdomen strapped resulted in a 40% increase in transdiaphragmatic pressure (Pdi) (p less than 0.005), but neither the peak inspiratory pleural pressure relative to the relaxation curve nor the minute ventilation differed from those of the control study (p greater than 0.7). Nevertheless, strapped exercise endurance (119 +/- 27 s) was significantly lower than control endurance (154 +/- 35 s; p less than 0.01). Because of the increase in Pdi, the computed tension-time index of the diaphragm increased from a control value of 0.13 +/- 0.05 to 0.20 +/- 0.06 (p less than 0.05) when strapped. However, neither the pleural pressure nor the Pdi swings decreased during the last 30 s of the runs, indicating that inspiratory muscle fatigue was not the basis for the reduced endurance when the abdomen was strapped. Strapping the abdomen may improve the length-tension relationship of the diaphragm at a given lung volume, and the increased Pdi suggests improved diaphragmatic function.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdomen↗

PubMed1981

Progression of clinical signs in severe infant botulism. Therapeutic implications.

The clinical evaluation of nine patients with severe infant botulism revealed an identifiable progression of signs due to blockade of the cholinergic synapse similar to that described for competitive blocking agents. This predictable sequence reflects different "margins of safety" for muscles involved in repetitive activities, diaphragmatic function and movement of the extremities. It is important for the clinician to realize that return of peripheral motor activity does not signify a completely recovered cholinergic synapse. Instead of having a four- to five-fold margin of safety, the infant remains close to the point of neuromuscular blockade. Added insults or stress to neuromuscular transmission may precipitate respiratory failure. An understanding of the signs associated with progressive impairment of cholinergic synapses both during onset and during resolution of disease will allow safe care of the infant and will diminish the risk of iatrogenic complications. Evaluation of head control is the most sensitive physical finding indicative of return of adequate neuromuscular function and signifies that oral feedings can be reinstituted.

Autonomic Nervous System↗

PubMed1993

Effect of nasal pressure support ventilation and external PEEP on diaphragmatic activity in patients with severe stable COPD.

Nasal pressure support ventilation (NPSV) has been shown to be useful in the treatment of acute and chronic pulmonary failure. However, little is known about respiratory muscle activity during NPSV in stable patients with COPD. The aim of this study was to test the effect of two levels (10 and 20 cm H2O) of NPSV on diaphragmatic activity, in a group of seven stable, severe COPD patients (FEV1 20 percent +/- 7 of pred, FEV1/FVC 35 percent) with hypercapnic respiratory insufficiency. Since these patients had an intrinsic PEEP (PEEPi) of 2.6 +/- 1.3 cm H2O, we also investigated the effect of adding 5 cm H2O external PEEP (PEEPe) during NPSV. Blood gases, ventilatory pattern by inductive plethysmography, integrated electromyogram of the diaphragm (Edi), transdiaphragmatic pressure (Pdi), and the diaphragmatic pressure time product (PTPdi) were recorded during randomized 15-min runs of both levels of NPSV with and without the addition of PEEPe. Minute ventilation did not change with the application of NPSV, but a significant decrease in breathing frequency with a parallel increase in tidal volume was observed, so that blood gas determinations improved at the higher levels of support. A marked statistically significant reduction in diaphragmatic activity, as assessed by a decrease in Pdi swings, PTPdi, and Edi, was detected at the levels of 10 and 20 cm H2O; a further significant decrease in these values was observed when PEEPe was added. PEEPi decreased significantly only with the application of PEEPe, resulting in a small increase in end-expiratory lung volume. We conclude that NPSV improves diaphragmatic function in patients with severe stable COPD; this effect may be enhanced by the applications of external PEEP.

Aged↗

PubMed1995

Diaphragmatic flutter presenting as inspiratory stridor.

Diaphragmatic flutter is a rarely reported disorder in which the diaphragm involuntarily contracts at a rapid rate. We report a unique case in which diaphragmatic flutter was associated with inspiratory stridor and was severely disabling. A new approach to the treatment of this condition, phrenic nerve crush, provided an optimal outcome, with resolution of symptoms and the return of normal diaphragmatic function. Pathophysiology and treatment of this condition are discussed.

Adolescent↗

PubMed1980

Phrenic nerve injury associated with venipuncture of the internal jugular vein.

Coincident with repeated, unsuccessful efforts to place a transvenous pacemaker through the right internal jugular vein, and 81-year-old man developed paralysis of the right hemidiaphragm. The patient had sudden shortness of breath and hypoxemia that rapidly subsided, although the loss of diaphragmatic function appears to be permanent.

Aged↗

PubMed1985

Electrophysiologic evaluation of phrenic nerves in severe respiratory insufficiency requiring mechanical ventilation.

Diaphragmatic paralysis in patients with respiratory insufficiency compounds the problems in the management. In the presence of lower lobe atelectasis, pleural effusion, or a patient's poor respiratory effort, fluoroscopic examination is often not a reliable way to diagnose diaphragmatic paralysis. We observed that transcutaneous phrenic nerve stimulation in the neck and recording the diaphragmatic potentials from electrodes placed on the lower part of the chest is a simple, reliable, and noninvasive technique to diagnose diaphragmatic dysfunction at the bedside in critically ill patients. In 14 postoperative patients and one with cervical spinal cord injury with respiratory failure, we found ten patients who showed phrenic nerve dysfunction. Besides diagnostic utility, the electrophysiologic evaluation of phrenic-diaphragmatic function provides critical information needed for therapy.

Adult↗