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PubMed1990

[Lung function diagnosis using multi-frequency oscillometry with reference to lung volume].

The ranking of various oscillometry parameters was to be tested in patients with a broad spectrum of disturbances of pulmonary function, objectified by body plethysmographic and technical oesophageal pressure measurement of the respiratory resistance, lung volumes and lung elasticity. For this purpose the oscillatory resistance Rfo and the phase angle phi were measured at 8, 12 and 16Hz and phi was measured as it changed, depending on the lung volume V. It was found that enhanced respiratory resistance values are satisfactorily represented by Rfo for the purposes of preliminary and basic diagnostics. Besides, enhanced Rfo values are markedly dependent on the frequency, phi being shifted to negative values. Difference between Rfo values at 8 and 16 Hz (delta R8-16) less than 0.7 hPa/l/s phi greater than or equal to -10 degrees can be considered as being still normal with the employed measuring principle and are a valuable supplement for assessing the degree of obstruction. The difference between phi in the medium respiratory position and at 90 or 100% total capacity (delta phi) is less than 5 degrees during slow inspiration in 80% of the patients suffering from emphysema. In 80% of the persons with healthy lungs and those suffering from fibrosis there is an inspiratory negativation of phi (delta phi greater than 5 degrees) so that the phi-V relationship appear suitable for distinguishing patients with restricted vital capacity in respect of emphysema and fibrosis. Patients suffering fron fibrosis differ from healthy subjects by slightly more negative phi values. The borderline values for delta R8-16, phi and delta phi were confirmed in two further series of examinations on children and adolescents.

Adult↗
PubMed1993

Recruitment of some respiratory muscles during three maximal inspiratory manoeuvres.

BACKGROUND: A study was undertaken to determine the level of recruitment of the muscles used in the generation of respiratory muscle force, and to ascertain whether maximal diaphragmatic force and maximal inspiratory muscle force need to be measured by separate tests. The level of activity of three inspiratory muscles and one expiratory muscle during three maximal respiratory manoeuvres was studied: (1) maximal inspiration against a closed airway (Muller manoeuvre or maximal inspiratory pressure (MIP)); (2) maximal inspired manoeuvre followed by a maximal expiratory effort (combined manoeuvre); and (3) maximal inspiratory sniff through the nose (sniff manoeuvre). METHODS: All the manoeuvres were performed from functional residual capacity. The gastric (PGA) and oesophageal (POES) pressures and their difference, transdiaphragmatic pressure (PDI), and the integrated EMG activity of the diaphragm (EDI), the sternomastoid (ESTR), the intercostal parasternals (ERIC), and the rectus abdominis muscles (ERA) were recorded. RESULTS: Mean (SD) PDI values for the Muller, combined, and sniff manoeuvres were: 127.6 (19.4), 162.7 (22.2), and 136.6 (24.8) cm H2O, respectively. The pattern of rib cage muscle recruitment (POES/PDI) was similar for the Muller and sniff manoeuvres (88% and 80% respectively), and was 58% in the combined manoeuvre, confirming data previously reported in the literature. Peak EDI amplitude was greater during the sniff manoeuvre in all subjects (100%) than during the combined (88.1%) and Muller (61.1%) manoeuvres. ESTR and EIC were more active in the Muller and the sniff manoeuvres. The contribution of the expiratory muscle (ERA) to the three manoeuvres was 100% in the combined, 26.1% for the sniff, and 11.5% for the Muller manoeuvre. CONCLUSIONS: Each of these three manoeuvres results in different mechanisms of inspiratory and expiratory muscle activation and the intrathoracic and intra-abdominal pressures generated are a reflection of the interaction between the various muscle groups. The Muller and sniff manoeuvres reflect mainly the force of the inspiratory muscles and the combined manoeuvre that of the diaphragm.

Adult↗
PubMedDate not supplied

Interpretation of changes in spirographic and flow-volume variables after operative treatment in bilateral vocal cord paralysis.

In 13 patients, who underwent a superolateralization of a vocal cord after bilateral vocal cord paralysis, we studied pre- and postoperatively spirometric dynamic and static lung volumes and variables from maximal expiratory and maximal inspiratory flow-volume (MEFV and MIFV) curves. The effects of surgical treatment on these variables have been established by comparing the statistical significance of the changes post- versus preoperative. A significant increase was found in the vital capacity and a significant decrease in the indices associated with the dynamic variability of the obstruction. The most significant changes were found in peak inspiratory flow and peak expiratory flow, and in the inspiratory defined dynamic estimates, as forced inspiratory volume in 1 second and maximal voluntary ventilation at a frequency of 30 c X min-1. Significant correlations, however, were found to exist only for the changes within the group of flow-volume indices and for those within the group of spirographic variables. This led us to the conclusion that for the diagnosis of this type of upper airway obstruction these measurements are additive, reflecting different aspects of airway mechanics.

Adult↗
PubMed1995

Central and reflex neural control of genioglossus in subjects who underwent laryngectomy.

Inspiratory activation of the genioglossus (GG) may occur by central drive or as a reflex to negative airway pressure. To distinguish between these, we studied seven laryngectomy patients who breathe via tracheal stomas. Negative pressure stimuli (-15 and -25 cmH2O for 500 ms) were applied 1) at functional residual capacity and 2) during early inspiration via (i) the upper airway (UA) and (ii) the tracheal stoma. Intraoral surface GG electromyogram was quantified, as described previously (R. L. Horner, J. A. Innes, K. Murphy, and A. Guz, J. Physiol. Lond. 436: 15-29, 1991). Phasic GG activity was also measured from an integrated electromyogram during spontaneous and inspiratory loaded breathing. Reflex GG activation occurred with negative UA pressure both at functional residual capacity and during inspiration (P < 0.001), but pressure stimuli at the stoma caused no significant activation (P = 0.07). Phasic inspiratory activation occurred in four patients at rest and in all seven patients during inspiratory loading (P < 0.02). These patients demonstrate 1) reflex activation of the GG by negative UA pressure without airflow or respiratory effort and 2) central inspiratory GG activation that is not mediated by negative airway pressure.

Aged↗
PubMed2005

The influences of positive end expiratory pressure (PEEP) associated with physiotherapy intervention in phase I cardiac rehabilitation.

PURPOSE: To evaluate the effects of positive end expiratory pressure and physiotherapy intervention during Phase I of cardiac rehabilitation on the behavior of pulmonary function and inspiratory muscle strength in postoperative cardiac surgery. METHODS: A prospective randomized study, in which 24 patients were divided in 2 groups: a group that performed respiratory exercises with positive airway expiratory pressure associated with physiotherapy intervention (GEP, n = 8) and a group that received only the physiotherapy intervention (GPI, n = 16). Pulmonary function was evaluated by spirometry on the preoperative and on the fifth postoperative days; inspiratory muscle strength was measured by maximal inspiratory pressure on the same days. RESULTS: Spirometric variables were significantly reduced from the preoperative to the fifth postoperative day for the GPI, while the GEP had a significant reduction only for vital capacity (P < .05). When the treatments were compared, smaller values were observed in the GPI for peak flow on the fifth postoperative day. Significant reductions of maximal inspiratory pressure from preoperative to the first postoperative day were found in both groups. However, the reduction in maximal inspiratory pressure from the preoperative to the fifth postoperative day was significant only in the GPI (P < .05). CONCLUSIONS: These data suggest that cardiac surgery produces a reduction in inspiratory muscle strength, pulmonary volume, and flow. The association of positive expiratory pressure with physiotherapy intervention was more efficient in minimizing these changes, in comparison to the physiotherapy intervention alone. However, in both groups, the pulmonary volumes were not completely reestablished by the fifth postoperative day, and it was necessary to continue the treatment after hospital convalescence.

Cardiac Surgical Procedures↗
PubMed1993

The respiratory muscles in multicore myopathy.

Multicore myopathy is a rare congenital myopathy that can cause progressive weakness, but it has not been recognized previously to have respiratory consequences. This study describes two patients who developed respiratory failure because of respiratory muscle weakness. Both patients had low vital capacities without evidence of airway obstruction, and CO2 retention. Physical examination found that neck accessory muscles and abdominal muscles were very weak. In inspiration the abdomen expanded, but the rib cage contracted. Detailed studies were done in one patient with magnetometers, esophageal and gastric pressures, flow and volume, and electromyograms of abdominal and neck accessory muscles. Peak static inspiratory and expiratory pressures were 28 and 30 cm H2O, respectively, and maximal transdiaphragmatic pressure was 28 cm H2O. Vital capacity was reduced to 44% of predicted. Lung compliance was normal. In spontaneous breathing while supine, rib-cage diameters decreased while gastric pressure increased in inspiration, suggesting the weak diaphragm was the main muscle of respiration. EMG recordings showed no evidence of recruitment of the wasted neck accessory muscles (sternocleidomastoid and scalene), whereas electromyograph plus mechanics measurements gave evidence of abdominal muscle use in the sitting but not the supine posture. More limited studies in the second patient gave similar results. Multicore disease in these two patients thus caused marked weakness of all respiratory muscles, affected the intercostal-accessory group more than the diaphragm, and led to respiratory failure.

Adolescent↗
PubMedDate not supplied

Polysomnography in chronic neuromuscular disease.

BACKGROUND: Sleep is a risk factor for respiratory failure in patients with chronic neuromuscular diseases (NMD). OBJECTIVE: To explore the diagnostic value of monitoring sleep parameters in addition to nocturnal respiratory parameters. METHODS: Thirty-one patients with chronic NMD underwent whole-night polysomnograms including EMG from accessory respiratory muscles. RESULTS: Sleep macrostructure was normal on average. The number of respiratory arousals per hour of sleep was above the upper limit observed in a control group (>2.1) in 71% of the patients, but was moderate in most cases. Nadir oxygen saturation <85% was the most common finding indicating respiratory dysfunction and was present in 80% of the patients. Noninvasive blood gas monitoring identified all but 2 patients with respiratory-induced sleep abnormalities. The respiratory arousal rate was correlated with the oxygen desaturation index, but otherwise there were no significant correlations between sleep and nocturnal respiratory parameters. Vital capacity was significantly positively correlated with obstructive apnea index and daytime base excess to nadir oxygen saturation. Inspiratory activity in accessory respiratory muscles was present during REM sleep and/or slow wave sleep in 70% of the patients. CONCLUSION: The severity of nocturnal respiratory dysfunction is not reflected in the extent of sleep impairment in patients with chronic neuromuscular diseases.

Adult↗
PubMed1992

Effect of helium and oxygen on airflow in a narrowed airway.

A mixture of 80% helium and 20% oxygen has physical properties that increase airflow and decrease resistance in the airway when used as a portion of inspired gas. This study was designed to demonstrate and quantify the effects of a helium-oxygen mixture in a normal airway and when airway resistance is increased. Thirty healthy volunteers were studied breathing room air and the helium-oxygen mixture through a normal airway and an airway that included a resistor. Pulmonary function tests, directed by a registered respiratory therapist, were performed on all subjects using a computerized spirometer. The functional vital capacity, one-second forced expiratory volume, half-second forced expiratory volume, and peak inspiratory flow rate were analyzed. There was a statistically significant increase in 1-second forced expiratory volume using a helium-oxygen mixture in a normal airway. All pulmonary function test scores statistically improved when volunteers inspired helium and oxygen through the restricted airway, demonstrating that helium and oxygen can increase airflow in the presence of an increased airway resistance. This substantiates a role for helium and oxygen in treating conditions associated with decreased airway size and increased airway resistance.

Adult↗
PubMed2006

Role of small airways in asthma: investigation using high-resolution computed tomography.

BACKGROUND: Small airways may have an important role in asthma but are more difficult to assess pathologically than central airways. Computed tomographic indices of lung density are assumed to reflect air trapping and may be a useful noninvasive measure of small airways disease, but their pathophysiological relevance remains undetermined. OBJECTIVE: To evaluate lung density on high-resolution computed tomography and examine its correlations with clinical and physiologic variables in 29 patients with stable asthma. METHODS: Both lungs were scanned at full-inspiratory and full-expiratory phases to quantify percentage of lung field occupied by low attenuation area (LAA%; < -960 Hounsfield units) and mean lung density. Asthma severity, pulmonary function, methacholine airway sensitivity and reactivity, and sputum eosinophil counts were evaluated. RESULTS: The mean lung density increased and LAA% decreased in all patients at expiratory phase compared with inspiratory phase. The inspiratory density indices and expiratory mean lung density correlated only with FEV(1)/forced vital capacity (FVC). Expiratory LAA% correlated more strongly than other variables with FEV(1)/FVC and with indices of peripheral airflow obstruction. Expiratory/inspiratory ratios of LAA% and mean lung density correlated, the former more strongly, with disease severity, residual volume/total lung capacity, and airway sensitivity, as well as with indices of global (FEV(1) and FEV(1)/FVC) and peripheral airflow obstruction. CONCLUSION: Expiratory/inspiratory high-resolution computed tomography is useful for assessing small airways disease in asthma. Small airways involvement is associated with airflow obstruction, airway hypersensitivity, and more severe disease. CLINICAL IMPLICATIONS: Small airways are an important therapeutic target in asthma.

Adult↗
PubMed2006

Respiratory muscle training in persons with spinal cord injury: a systematic review.

The purpose of this paper was to review the effectiveness of respiratory muscle training (RMT) on respiratory muscle strength and endurance, pulmonary function, quality of life, respiratory complications and exercise performance in persons with spinal cord injury. A MEDLINE (National Library of Medicine, Bethesda, MD, USA) database was used for selection of the literature (from 1980 to November 2004), and relevant references from peer-reviewed articles were retrieved as well. Studies investigating the effects of RMT (i.e. resistive breathing weight lifting or normocapnic hyperpnea) in persons with spinal cord injury were selected. Two independent reviewers investigated controlled studies for methodological quality by using a modification of the framework for methodological quality. Methodological quality ranged between 15 and 29 (maximal feasible score=40). Twenty-three papers were retrieved and six controlled trials were kept for further analysis. A meta-analysis and calculation of effect-size of each individual study and weighted summary effect-size was intended. However, unreported data and heterogeneity in outcome variables did not allow performing a meta-analysis. From the systematic review it is concluded that RMT tended to improve expiratory muscle strength, vital capacity and residual volume. Insufficient data was available to make conclusions concerning the effects on inspiratory muscle strength, respiratory muscle endurance, quality of life, exercise performance and respiratory complications.

Exercise Therapy↗
PubMed2002

Respiratory muscle performance and the Perception of dyspnea in Parkinson's disease.

BACKGROUND: Pulmonary and respiratory muscle function impairment are common in patients with Parkinson's disease (PD). However, dyspnea is not a frequent complaint among these patients, although it is well documented that the intensity of dyspnea is related to the activity and the strength of the respiratory muscles. PATIENTS AND METHODS: We studied pulmonary function, respiratory muscle strength and endurance and the perception of dyspnea (POD) in 20 patients with PD (stage II and III Hoehn and Yahr scale) before and after their first daily L-dopa dose. Respiratory muscle strength was assessed by measuring the maximal inspiratory and expiratory mouth pressures (PImax and PEmax), at residual volume (RV) and total lung capacity (TLC) respectively. The POD was measured while the subject breathed against progressive load and dyspnea was rated using a visual analog scale. RESULTS: Respiratory muscle strength and endurance were decreased and the POD was increased during the off medication period compared to normal subjects. There was a nonsignificant trend to an increase in Plmax, PEmax and endurance after L-dopa intake. The POD of PD patients decreased (p<0.05) following medication, although, it remained increased (p<0.01) as compared to the normal subjects. Even if patients had spirometry data showing a mild restrictive pattern, before medication, both forced vital capacity (FVC) and forced expiratory volume (FEV)1 remained almost identical after L-dopa intake. CONCLUSIONS: Patients with PD have higher POD, compared to normal subjects and this increased perception is attenuated when the patients are on dopaminergic medication. The change in the POD is not related to changes in respiratory muscle performance or pulmonary functions. A central effect or a correction of uncoordinated respiratory movements by L-dopa may contribute to the decrease in POD following L-dopa treatment.

Aged↗
PubMedDate not supplied

Kyphoscoliosis ventilatory insufficiency: noninvasive management outcomes.

OBJECTIVE: To determine the effects on symptoms, pulmonary function, sleep, and other clinical variables of treating kyphoscoliosis-associated chronic alveolar hypoventilation with nocturnal nasal ventilation. DESIGN: Sixteen patients with kyphoscoliosis were treated with nocturnal nasal ventilation delivered by volume-cycled (seven patients) and pressure-cycled (nine patients) ventilators. Dyspnea, morning headaches, fatigue, hypersomnolence, and perceived sleep quality were assessed. RESULTS: All pretreatment symptoms improved significantly with nasal ventilation. Likewise, PaO2 (mm Hg), PaO2/FlO2, PaCO2 (mm Hg), pH, and forced vital capacity (in milliliters and as a percentage of predicted normal) significantly improved with treatment. Maximum inspiratory pressures and maximum expiratory pressures also significantly increased. Tidal volumes increased significantly and breathing frequency decreased (not significant). Although perceived sleep quality improved, as well as sleep oxyhemoglobin saturation, there was no significant change in sleep architecture. Hospitalization days for respiratory difficulties also decreased from 10.9 +/- 13.3 days in the 6 mo before intermittent positive-pressure ventilation to 0 days during the first 6 mo of treatment. CONCLUSIONS: Although not apparently affecting sleep architecture, nocturnal nasal ventilation can significantly improve nocturnal and daytime blood gases, pulmonary function, and symptoms of hypoventilation for patients with severe kyphoscoliosis.

Adult↗
PubMed1981

Pulmonary function in familial amyloidosis with polyneuropathy.

Pulmonary function tests were performed in 14 patients with familial amyloidosis with polyneuropathy. Low maximum expiratory and inspiratory pressures were found in all patients with advanced polyneuropathy, indicating that the neuropathy in this disease involves not only the extremities but also the respiratory muscles. The spirometric findings were consistent with a slight restrictive pattern in several patients, but in two of them the expiratory and inspiratory flows were also low. The intrapulmonary gas distribution was uniform in all. The diffusing capacity was reduced in patients who had had the disease for a long time, which suggests alveolo-capillary block caused by amyloid deposits. The arterial oxygen tension at rest was essentially normal in these patients.

Adult↗
PubMed1983

Target device for regulating ventilation during voluntary hyperpnea.

A ventilatory target device is described enabling subjects to maintain specified levels of ventilation during voluntary hyperpnea. Inspired air passes through a linear resistor. The associated pressure drop is measured and displayed by a mechanical manometer with a very slow response. This time-mean pressure is proportional to time-mean inspiratory flow and thus to inspired minute ventilation. Construction and calibration are described. Inspiratory resistances range between 0.6 and 1.9 cmH2O X 1(-1)S for devices with capacities up to 240 and 80 l/min, respectively. The device is simple, cheap, stable, portable, rugged, unpowered, and accurate. Inexperienced subjects quickly learn to use it and can maintain ventilations within about 5% of specified values.

Humans↗
PubMed1989

Inspiratory action of separate external and parasternal intercostal muscle contraction.

We have previously shown that electrical stimulation of the thoracic spinal cord produces near maximal activation of the inspiratory intercostal muscles. In the present investigation, we used this technique to evaluate the relative capacity of separate external (EI) and parasternal intercostal (PA) muscle contraction to produce changes in airway pressure and inspired volume. Studies were performed in 23 anesthetized phrenicotomized dogs. Electrical stimuli were applied to the spinal cord after hyperventilation-induced apnea, before and after sequentially severing either the PA or EI muscles from the first through sixth intercostal spaces. During spinal cord stimulation (SCS), measurements were made of inspired volume (delta V) with the airway open and negative airway pressure (delta P) during tracheal occlusion. Compared with control values, sectioning of the PA muscles resulted in a 40.9% reduction in delta P and 35.7% reduction in delta V during SCS. In other animals, initial sectioning of the EI muscles produced reductions in delta P and delta V of 67.4 and 63.0, respectively, during SCS. After subsequent section of the PA muscles, SCS produced only negligible inspired volumes and changes in airway pressure. We conclude that 1) the EI and PA muscles are each capable of generating substantial changes in airway pressure and large inspired volumes and 2) the ventilatory capacity of the EI muscles exceeds that of the PA muscles.

Animals↗
PubMed1983

Chest wall configurational changes before and during acute obstructive episodes in asthma.

We induced bronchial obstruction in 7 otherwise healthy asthmatic subjects and then measured the degree of airway obstruction and the dimensions of the chest wall including the anteroposterior (AP) diameters of the upper and lower rib cage and the abdomen and the transverse diameter of the lower rib cage. Airway obstruction was accompanied by a pronounced increase in the end-expiratory AP diameter of the upper rib cage in all 7 subjects and of the low lateral rib cage in 3 of the 4 subjects in whom this was measured. Other end-expiratory dimensions showed variable changes. In 6 of 7 subjects, obstruction caused the lower rib cage to become more elliptical in cross section during inspiration; transient inward motion of the lower anterior rib cage during early inspiration was noted. This latter motion coupled with the continuous outward motion of the upper anterior rib cage produced a pronounced rocking motion of the sternum during inspiration. These distortions of the chest cage were maximal when obstruction was most severe and gradually diminished as obstruction resolved. These inspiratory changes in chest cage cross-sectional configuration are similar to those seen in normal subjects who attempt to overcome external resistive loading by the increased use of inspiratory muscles; the end-expiratory configuration in asthma indicates an increase in functional residual capacity, which is actively maintained. Multiple degrees of freedom of motion of the chest cage exist during obstructive episodes. Estimates of volume change from measurements of rib cage cross-sectional area and abdominal diameter should be made with caution.

Abdomen↗
PubMed1994

Diaphragmatic and abdominal muscle activity after endoscopic cholecystectomy.

We studied diaphragmatic and abdominal muscle activity immediately and 16 h after laparoscopic cholecystectomy (LAPC). Tidal volumes (VT), partitioning of VT between the rib cage and the abdomen, and esophageal, gastric, and transdiaphragmatic pressures were recorded for 5 min every 15 min up to 90 min after the end of anesthesia in 10 young patients submitted to an elective LAPC. All had chest radiographs in full inspiration and expiration as well as lung function tests (LFTs) before and 16 h after surgery. In 5 of the 10 patients, thoracoabdominal patterns of breathing were also measured before both LFTs. After LAPC, VT did not change. There was no significant shift from abdominal to thoracic respiration. No paradoxical respiration developed. Functional residual capacity (FRC) and residual volume (RV) remained normal. However, all measures of LFTs requiring maximum inspiratory effort decreased up to 20%. Tonic and phasic activity of the abdominal muscle appeared early in the recovery period and disappeared after 75 min. The diaphragm adjusted to this additional load so that VT remained constant. These results indicate that diaphragm function is intact during quiet breathing after LAPC, but slightly reduced when maximum effort is needed. However, this represents a net gain over the changes previously described after classic "open" cholecystectomy (OC).

Abdominal Muscles↗
PubMed1993

A comparison of breath-actuated and conventional metered-dose inhaler inhalation techniques in elderly subjects.

BACKGROUND: Poor coordination of canister actuation and inspiration often prevents adequate metered-dose inhaler (MDI) usage by patients, perhaps especially so among the elderly. Breath-actuated inhalers (BAI) have been developed to prevent this problem. METHODS: We compared the adequacy of inhaler technique and patient preferences between MDI and BAI in a group of elderly subjects (mean age, 70.8 +/- 5.4 years). Half of the subjects were regular MDI users; half had never before used one. Two trained observers assessed the adequacy of MDI and BAI usage subjectively while performance was monitored objectively using a light source and infrared system to detect canister actuation and a spirometer to measure the inspiratory volume. If canister actuation was not followed by at least a 50 percent vital capacity, inhaler use was deemed unsuccessful. A brief teaching session preceded inhaler usage. RESULTS: By subjective assessment, BAI was used successfully more often than MDI (79 vs 60 percent, p < 0.05). By objective assessment, BAI was used successfully more often than MDI (64 vs 36 percent, p < 0.0005), although the percentage of inhalations scored adequate was lower than when assessment was subjective. Neither device was used correctly as often by those unfamiliar with MDIs as by those who were regular users. A significantly higher percentage of patients preferred BAI to MDI (71 vs 19 percent, p < 0.005), similar preferences being reported by MDI familiar and MDI unfamiliar groups. CONCLUSIONS: We conclude that (1) elderly subjects frequently handle inhalers poorly, (2) mishandling is better detected by objective than subjective monitoring, and (3) BAI is used correctly and preferred by patients more often than conventional MDIs.

Administration, Inhalation↗