Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Inspiratory Capacity”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 1,117 records · Page 62Linked to original sources
PubMed1975

Diagnosis of upper airway obstruction by pulmonary function testing.

We compared 11 patients with upper airway obstruction (obstruction at or proximal to the carina) to 22 patients with chronic obstructive pulmonary disease and to 15 normal subjects utilizing spirometry, lung volumes, airway resistance, maximal voluntary ventilation, single-breath diffusion capacity, and maximal inspiratory and expiratory flow-volume loops. Four values usually distinguished patients with upper airway obstruction: (1) forced inspiratory flow at 50 percent of the vital capacity (FIF50%) less than or equal to 100 L/min; (2) ratio of forced expiratory flow at 50 percent of the vital capacity of the FIR50% (FEF50%/FIF50%) larger than or equal to 1; (3) ratio of the forced expiratory volume in one second measured in milliliters to the peak expiratory flow rate in liters per minute (FEV1/PEFR) larger than or equal to 10 ml/L/min; and (4) ratio of the forced expired volume in one second to the forced expired volume in 0.5 second (FEV1/FEV0.5) larger than or equal to 1.5. The last ratio can be determined with a simple spirometer.

Adult↗
PubMed1994

[Initial heart rate transient at dynamic exercise performed in apnea. Influence of the variation rate of previous lung volume].

PURPOSE: To study the influence of inspiratory flow on the heart rate (HR) responses during the four-second exercise test (4sET) as a method to estimate cardiac vagal activity. METHODS: Fifteen healthy subjects performed the 4sET under two experimental situations: a) with maximal individual inspiratory flow (MIF) and b) with a slow inspiratory flow adjusted to reach total lung capacity in 4s (SIF). Vagal activity was estimated from B/C ratio obtained in ECG tracings, where B is the last R-R interval before the onset of exercise and C is the shortest R-R interval during exertion. RESULTS: Similar inspiratory capacities were reached, with significantly different inspiratory flows [mean (se)] [MIF = 2.23 (0.28) 1.s-1 and SIF = 0.59 (0.06) 1.s-1; t = 6.69; p < 0.0001]; as a result, it was observed a greater B/C ratio in MIF [1.36 (0.05)] as compared to SIF [1.13 (0.04); t = 4.42; p = 0.0006]. The inspiratory flow influenced HR responses in the 4sET. The biphasic transient induced by inspiration, with a HR acceleration followed by a relative bradycardia, has not been completed before exercise in the 4sET with SIF. CONCLUSION: Lower values of B/C in the 4sET with SIF seemed to be due to overlapping effects of apnea and exertion on HR during cycling. On the other hand, when the inspiration was performed at MIF, the oscillatory effect of respiration upon HR was completed before the onset of exercise. Therefore, the tachycardia observed during the 4sET performed after individual maximal inspiratory flow represents the isolated effect of dynamic exercise.

Adolescent↗
PubMed2001

Inspiratory muscle strength in acute asthma.

STUDY OBJECTIVES: The aim of this study was to measure inspiratory pressure-generating capacity in patients presenting with acute asthma, as it has been suggested that inspiratory muscle fatigue may contribute to breathlessness and acute respiratory failure. DESIGN: Descriptive study. SETTING: Emergency departments of two inner-city hospitals. PATIENTS: Fifty-one patients with acute asthma, and 45 patients without respiratory disease who served as control subjects. MEASUREMENTS AND RESULTS: Maximum inspiratory pressure-generating capacity was measured soon after presentation by the sniff nasal inspiratory pressure (SNIP) method. The mean (SD) SNIP was 110 cm H(2)O (23 cm H(2)O) in men with asthma (mean for control subjects, 126 cm H(2)O [25 cm H(2)O]; p < 0.05) and 80 cm H(2)O [24 cm H(2)O] in women with asthma (mean for control subjects, 105 cm H(2)O (26 cm H(2)O); p < 0.01). In a second study of simultaneous SNIP and intrathoracic pressure measurements in a group of patients with acute asthma (n = 10) and control subjects (n = 11), the effect of airways obstruction on SNIP was assessed. The measurement of sniff esophageal pressure was more negative than SNIP by approximately 16% in asthmatic patients and by 4% in control subjects. Taking account of the likely effect of airways obstruction on SNIP, the reduction in inspiratory pressure-generating capacity that was observed in these patients with moderately severe acute asthma was minor and was consistent with the modest hyperinflation observed. CONCLUSIONS: This study did not find evidence of inspiratory muscle weakness or fatigue in patients with moderately severe acute asthma presenting to the emergency department.

Adolescent↗
PubMed2006

Impact of impaired inspiratory muscle strength on dyspnea and walking capacity in sarcoidosis.

BACKGROUND: Dyspnea and fatigue are frequent but poorly understood symptoms in sarcoidosis patients. This study was aimed at assessing the clinical impact of inspiratory muscle impairment on dyspnea and exercise tolerance. This is the first study using nonvolitional tests that are independent of the patient's cooperation and motivation in addition to volitional tests of inspiratory muscle strength in patients with sarcoidosis. METHODS: Peak maximal inspiratory mouth pressure (Pimaxpeak), maximal inspiratory pressure sustained for 1.0 s (Pimax1.0), twitch mouth pressure (TwPmo), lung function test results, blood gas measurements, 6-min walking distance (6MWD), and Borg dyspnea scale (BDS) scores were assessed in 24 male sarcoidosis patients and 24 healthy male control subjects matched for age and body mass index. RESULTS: Mean (+/- SD) Pimaxpeak (95.2 +/- 25.3% vs 124.6 +/- 23.4% predicted, respectively; p < 0.001) and Pimax1.0 (85.6 +/- 31.4% vs 125.8 +/- 26.8% predicted, respectively; p < 0.001) were lower in sarcoidosis patients compared to control subjects. TwPmo tended to be lower in sarcoidosis patients, and there were three patients who had TwPmo values of < 1.0 kPa, which is a strong indicator of inspiratory muscle weakness. The mean 6MWD was 582 +/- 97 m in sarcoidosis patients and 638 +/- 65 in control subjects (p = 0.025). The mean BDS score was higher in sarcoidosis patients (3.3 +/- 1.7 vs 0.2 +/- 0.5, respectively; p < 0.001). Compared to maximal inspiratory pressure, lung function parameters, and blood gas levels, TwPmo was the strongest predictor for 6MWD (r = 0.663; p = 0.003) and BDS score (r = 0.575; p = 0.012) in sarcoidosis patients following multiple linear regression analysis. CONCLUSIONS: Impairment of inspiratory muscle strength occurs in sarcoidosis patients, and has been suggested to be an important factor causing dyspnea and reduced walking capacity, but this is only reliably detectable when using nonvolitional tests of inspiratory muscle strength.

Adult↗
PubMed1998

Relationship between subjective fatigue and physiological variables in patients with chronic obstructive pulmonary disease.

Patients with chronic illnesses, such as chronic obstructive pulmonary disease (COPD), report an increase in the perception of fatigue in the clinical setting. Subjective fatigue associated with physiological factors has not been reported. The purpose of this study was to determine the relationship between subjective fatigue and pulmonary function, respiratory and peripheral muscle force and exercise capacity in patients with COPD. Nineteen patients with COPD participated in the study [mean (SD) FEV1 38% (17%) predicted]. Fatigue was measured with the Multidimensional Fatigue Inventory 20 (MFI-20) that includes the following subscale dimensions: general fatigue, physical fatigue, reduced activity, reduced motivation, and mental fatigue. The following physical variables were measured: forced expiratory volume in 1 s (FEV1), vital capacity (VC), maximal inspiratory peak pressure (PImax), symptom-limited bicycle exercise capacity (maximum workload) and maximal voluntary isometric muscle force of both left and right quadriceps (Qu), hamstrings (Ha), biceps (Bi) and triceps (Tr). The MFI-20 fatigue dimensions, reduced activity and reduced Motivation, are significantly correlated with FEV1 (% predicted) (r = -0.62, r = -0.55 respectively). No significant correlation was found between the dimensions of fatigue and maximum workload. In contrast the fatigue dimension, physical fatigue, shows significant correlations with seven of eight muscle forces measured (Qu left r = -0.49, right r = -0.54; Ha left r = -0.49, right r-0.38; Tr left r = -0.61, right r = -0.45; Bi left r = -0.46, right r = -0.48). Data from this study show that activity and physical dimensions of subjective fatigue are related to pulmonary function and skeletal muscle force in COPD patients. Interventions to improve skeletal muscle force might improve subjective fatigue in patients with COPD.

Exercise Tolerance↗
PubMed1991

Inspiratory muscle relaxation rate after voluntary maximal isocapnic ventilation in humans.

We have investigated whether the capacity of the inspiratory muscles to generate pressure and flow during a ventilatory load is related to changes in inspiratory muscle relaxation rate. Five highly motivated normal subjects performed voluntary maximal isocapnic ventilation (MIV) for 2 min. Minute ventilation and esophageal, gastric, and transdiaphragmatic pressures were measured breath by breath. We observed that ventilation, peak inspiratory and expiratory pressures, and inspiratory flow rate declined from the start of the run to reach a plateau at 60 s that was sustained for the remainder of the exercise. In a subsequent series of studies, MIV was performed for variable durations between 15 and 120 s. The normalized maximum relaxation rate of unoccluded inspiratory sniffs (sniff MRR, %pressure loss/10 ms) was determined immediately on stopping MIV. Sniff MRR slowed as the duration of MIV increased and paralleled the decline in inspiratory pressure and ventilation observed during the 2-min exercise. No further slowing in MRR occurred when ventilation became sustainable. We conclude that, during MIV, the progressive loss of ventilation and capacity to generate pressure is associated with the early onset and progression of a peripheral fatiguing process within the inspiratory muscles.

Adult↗
PubMed2005

Recovery of phrenic activity and ventilation after cervical spinal hemisection in rats.

We tested two hypotheses: 1) that the spontaneous enhancement of phrenic motor output below a C2 spinal hemisection (C2HS) is associated with plasticity in ventrolateral spinal inputs to phrenic motoneurons; and 2) that phrenic motor recovery in anesthetized rats after C2HS correlates with increased capacity to generate inspiratory volume during hypercapnia in unanesthetized rats. At 2 and 4 wk post-C2HS, ipsilateral phrenic nerve activity was recorded in anesthetized, paralyzed, vagotomized, and ventilated rats. Electrical stimulation of the ventrolateral funiculus contralateral to C2HS was used to activate crossed spinal synaptic pathway phrenic motoneurons. Inspiratory phrenic burst amplitudes ipsilateral to C2HS were larger in the 4- vs. 2-wk groups (P<0.05); however, no differences in spinally evoked compound phrenic action potentials could be detected. In unanesthetized rats, inspiratory volume and frequency were quantified using barometric plethysmography at inspired CO2 fractions between 0.0 and 0.07 (inspired O2 fraction 0.21, balance N2) before and 2, 3, and 5 wk post-C2HS. Inspiratory volume was diminished, and frequency enhanced, at 0.0 inspired CO2 fraction (P<0.05) 2-wk post-C2HS; further changes were not observed in the 3- and 5-wk groups. Inspiratory frequency during hypercapnia was unaffected by C2HS. Hypercapnic inspiratory volumes were similarly attenuated at all time points post-C2HS (P<0.05), thereby decreasing hypercapnic minute ventilation (P<0.05). Thus increases in ipsilateral phrenic activity during 4 wk post-C2HS have little impact on the capacity to generate inspiratory volume in unanesthetized rats. Enhanced crossed phrenic activity post-C2HS may reflect plasticity associated with spinal axons not activated by our ventrolateral spinal stimulation.

Action Potentials↗
PubMed2006

Evidence of ventilatory constraints in healthy exercising prepubescent children.

We assessed expiratory airflow limitation (exp FL) in 18 healthy prepubescent children (6 girls and 12 boys, 10.1 +/- 0.3 years old), and examined how it might modulate regulation of tidal volume (V(T)) during exercise. The children performed a maximal incremental exercise on a cycle ergometer, preceded and followed by pulmonary function tests. Throughout exercise, breathing flow-volume loops were plotted into the maximal flow-volume loop (MFVL) measured at rest. End-expiratory and end-inspiratory lung volumes were estimated by measuring expiratory reserve volume relative to forced vital capacity (ERV/FVC), and inspiratory reserve volume relative to forced vital capacity (IRV/FVC), respectively. The exp FL, expressed as a percentage of V(T), was defined as the part of the tidal breath meeting the boundary of the MFVL. Ten children (FL) presented an exp FL at peak exercise (range, 16-78% of V(T)), and the remaining 8 constituted a non-flow-limited group (NFL). At peak exercise, FL presented a higher IRV/FVC and lower ERV/FVC (P < 0.01) than NFL children, demonstrating two different exercise breathing patterns. These results suggest that the NFL regulated V(T) at high lung volume, avoiding exp FL, while the FL breathed at low lung volume, leading to exp FL. At peak exercise, FL presented lower values of minute ventilation (P<0.05) and oxygen uptake (P<0.05) than NFL. Nevertheless, oxygen arterial saturation and dyspnea were similar in the two groups. In conclusion, ventilatory constraints may occur in healthy prepubescent children and result in relative dynamic hyperinflation or expiratory flow limitation.

Child↗
PubMed2006

[The relationship between lung function and health-related quality of life in patients with generalized myasthenia gravis].

OBJECTIVE: To study lung function abnormalities and health-related quality of life (HRQL) in a group of patients diagnosed with generalized myasthenia gravis, and to analyze the relationship between these 2 sets of variables. PATIENTS AND METHODS: In a prospective study of 20 patients diagnosed with generalized myasthenia gravis, the following parameters were measured: spirometry, static lung volumes, breathing pattern, maximal respiratory pressures, and maximum voluntary ventilation. HRQL was assessed using the 36-item short form general health questionnaire (SF-36). RESULTS: The mean (SD) age of the patients was 64 (11) years. Patients were classified into 2 groups depending on whether they had IIa (12 patients) or IIb (8 patients) type disease. A small decrease in total lung capacity (86%) and slight reductions in maximal inspiratory pressure (88%) and maximum voluntary ventilation (63% in group IIb) were observed. The HRQL domains most affected were those related to physical activity and self-perceived health status in all groups, although women were more affected. The scores relating to vitality and physical activity were found to be significantly associated with forced vital capacity and lung volumes. Tidal volume was associated with maximal inspiratory and expiratory pressures, inspiratory capacity, and maximum voluntary ventilation. The respiratory rate to tidal volume ratio was inversely associated with the first three of these variables. CONCLUSIONS: A very slight restrictive pattern and a reduction in inspiratory muscle strength were observed. The HRQL domains most affected were those related to physical activity and the patients' self-perceived health status. The weakness of the respiratory muscles contributes to the abnormalities observed in lung function and to the deterioration of health-related quality of life.

Aged↗
PubMed1994

Relation of lung function, maximal inspiratory pressure, dyspnoea, and quality of life with exercise capacity in patients with chronic obstructive pulmonary disease.

BACKGROUND: Several studies have shown that both objective and subjective measurements are related to exercise capacity in patients with chronic obstructive pulmonary disease (COPD). In this study the relative contribution of lung function, maximal inspiratory pressure, dyspnoea, and quality of life to the performance in a walking distance test and a bicycle ergometer test was investigated. METHODS: Static lung volumes, forced expiratory volume in one second (FEV1), inspiratory slow vital capacity (IVC), transfer factor for carbon monoxide (TLCO) divided by the alveolar volume (TLCO/VA), static compliance (Cst), and maximal inspiratory peak pressure (PImaxPOES) were measured in 40 patients with COPD with severe airways obstruction (mean FEV1 44% predicted, mean FEV1/IVC 37% predicted). Quality of life was assessed by the Chronic Respiratory Questionnaire (CRQ) and dyspnoea by the Borg category scale. Exercise capacity was measured by both a six minute walking distance (test) and a maximal work load of the bicycle ergometer test (Wmax). RESULTS: Spirometric values and maximal inspiratory pressure were modestly correlated with both the six minute walking test and Wmax, r values ranging from 0.50 to 0.58. The TLCO was strongly correlated with the six minute walking test (r = 0.62) and with Wmax (r = 0.78). Quality of life showed no correlation with exercise capacity, while there was a correlation between dyspnoea and the six minute walking test (r = -0.41). Backward linear regression analysis selected TLCO and PImaxPOES as the most significant determinants for exercise performance. They explained 54% and 69% of the variance in the six minute walking test and Wmax, respectively. CONCLUSIONS: The results show that exercise capacity in patients with COPD with severe airways obstruction is more strongly related to inspiratory muscle strength and lung function than to dyspnoea and quality of life. The significant correlation between dyspnoea and the six minute walking test suggests that subjective variables are more strongly related to walking tests than to bicycle ergometer tests.

Aged↗
PubMed1983

Effect of high negative inspiratory pressure on single breath CO diffusing capacity.

We measured the single breath diffusing capacity for carbon monoxide (DLcoSB) using a three-equation method to describe CO uptake in 10 normal seated subjects who either voluntarily inhaled slowly (0.5 L/sec) to total lung capacity (TLC), or inhaled slowly to TLC with maximal effort through a high inspiratory resistance which created high negative inspiratory pressure. Subjects then immediately exhaled slowly at a voluntarily controlled exhaled flow. Single breath maneuvers were performed in duplicate both with and without high negative inspiratory pressure while subjects were seated upright at rest and during steady-state bicycle exercise. We found that high negative inspiratory pressure increased DLcoSB by 10.5 +/- 4.9% (mean +/- 1 SD) at rest (P less than 0.001). In 7 subjects low level exercise alone increased DLcoSB by a similar amount (12.1 +/- 7.3%; P = 0.005). In six of the subjects there was a significant correlation between the increase in DLcoSB during high negative inspiratory pressure at rest and the increase in DLcoSB during steady-state exercise (r = 0.89; P less than 0.01). During steady-state exercise, high negative inspiratory pressure further increased DLcoSB 6.4 +/- 6.3% compared to exercise alone (P = 0.05). We conclude that the increase in DLcoSB with high negative inspiratory pressure at rest is a simple reproducible method of assessing recruitment of the pulmonary capillary bed in man.

Adult↗
PubMed1984

Spirometric indices in the assessment of laryngeal obstruction.

To determine if spirometric indices allow detection and quantification of a laryngeal obstruction, we obtained oro-laryngeal airway resistance (Ro1) and several spirometric indices in 43 patients with various laryngeal diseases. Assuming Ro1 greater than or equal to 0.2 kPa/(1/s) to imply a laryngeal obstruction, the highest sensitivity was found for FIV1 = 2.0 1 (forced inspiratory volume in one second) being about 84% at a specificity of about 88%. The highest correlation coefficients (r = 0.72-0.83) were obtained between Ro1 and MIF50/MEF50 (the ratio between maximum expiratory and inspiratory flow at 50% of vital capacity) and between I/Ro1, and PIF (peak inspiratory flow), MIF50 and FIV1. In conclusion spirometric indices allow detection of a laryngeal obstruction in the majority of cases, but do not appear adequate for a quantitative assessment in an individual patient.

Adolescent↗
PubMed2004

Inspiratory muscle training improves lung function and exercise capacity in adults with cystic fibrosis.

STUDY OBJECTIVES: To investigate the effects of high-intensity inspiratory muscle training (IMT) on inspiratory muscle function (IMF), diaphragm thickness, lung function, physical work capacity (PWC), and psychosocial status in patients with cystic fibrosis (CF). DESIGN: Twenty-nine adult patients with CF were randomly assigned to three groups. Two groups were required to complete an 8-week program of IMT in which the training intensity was set at either 80% of maximal effort (group 1; 9 patients) or 20% of maximal effort (group 2; 10 patients). A third group of patients did not participate in any form of training and acted as a control group (group 3; 10 patients). INTERVENTIONS: In all patients, baseline and postintervention measures of IMF were determined by maximal inspiratory pressure (Pimax), and sustained Pimax (SPimax); pulmonary function, body composition, and physical activity status were also determined. In addition, diaphragm thickness was measured at functional residual capacity (FRC) and total lung capacity (TLC) [TDIcont], and the diaphragm thickening ratio (TR) was calculated (TR = thickness during Pimax at FRC/mean thickness at FRC). Subjects also completed an incremental cycle ergometer test to exhaustion and two symptom-related questionnaires, prior to and following training. RESULTS: Following training, significant increases in Pimax and SPimax (p < 0.05), TDIcont (p < 0.05), TR (p < 0.05), vital capacity (p < 0.05), TLC (p < 0.05), and PWC (p < 0.05) were identified, and decreases in anxiety scores (p < 0.05) and depression scores (p < 0.01) were noted in group 1 patients compared to group 3 patients. Group 2 patients significantly improved Pimax and SPimax (both p < 0.05) only with respect to group 3 patients. No significant differences were observed in group 3 patients. CONCLUSION: An 8-week program of high-intensity IMT resulted in significant benefits for CF patients, which included increased IMF and thickness of the diaphragm (during contraction), improved lung volumes, increased PWC, and improved psychosocial status.

Adult↗
PubMed1988

Assessment of diaphragm weakness.

Thirty patients with breathlessness and diaphragm weakness were studied by measuring transdiaphragmatic pressures during maximal inspirations to total lung capacity, maximal static inspiratory efforts from residual volume, and maximal sniffs from functional residual capacity. Maximal static respiratory mouth pressures were also recorded, and rib cage and abdominal movements were monitored with pairs of magnetometers. Sniff transdiaphragmatic pressure was abnormally low in all patients and was correlated with transdiaphragmatic pressure during other maneuvers, and with maximal static inspiratory mouth pressures. There was no relationship between the severity of dyspnea and transdiaphragmatic pressure in the group as a whole. The weakest patients had orthopnea and paradoxical inward inspiratory motion of the anterior abdominal wall; measurements suggested that at least 30 cm H2O transdiaphragmatic pressure was required to overcome the hydrostatic pressure of the abdominal contents. By contrast, patients with mild diaphragm weakness had neither orthopnea nor abdominal paradox. Thus, patients with breathlessness and diaphragm dysfunction may have varying degrees of diaphragm weakness that may be difficult to detect clinically; the diagnosis and quantification of diaphragm weakness requires the measurement of transdiaphragmatic pressure.

Adolescent↗
PubMed2005

Beta-blockers and inspiratory pulmonary function in chronic heart failure.

BACKGROUND: Chronic heart failure (CHF) patients complain of breathlessness and fatigue. Respiratory muscle function is impaired in CHF patients and may contribute to their symptoms. Beta-blockers cause fatigue but have become part of the standard management of CHF. We explored the relation between respiratory muscle power in CHF and the effects of long-term beta-blockade. METHODS AND RESULTS: A total of 52 CHF patients and 25 control subjects underwent echocardiography, peak exercise testing with metabolic gas exchange analysis, and measurement of forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), peak inspiratory flow (PIF), and forced inspiratory volume in 1 second (FIV1). Of the patients, 35 started beta-blocker therapy and were tested again at 1 year. Patients had lower peak oxygen consumption (pV(O2) (19.3 [4.5] versus 37.3 [8.4] mL/kg/min, P < .0001), exercise time (414 [134] versus 817 [193] seconds, P < .0001), and anaerobic threshold (13.8 [3.8] versus 27.2 [8.2] mL/kg/min, P < .0001). Patients also had a steeper relationship between ventilation (V(E)) and carbon dioxide (CO2 ) (V(E)/V(CO2)) (40.0 [6.8] versus 26.4 [2.0], P < .0001); lower FEV1, FVC, and FIV1 (89 [15] versus 111 [24]% expected, P < .0001, 80 [20] versus 94 [21]% expected, P < .001 and 2.5 [1.6] versus 3.0 (0.9) L, P < .02); and there was a correlation between pV(O2) and FIV1 (r = 0.24, P < .05) for the patients. The slope relating symptoms of breathlessness (Borg score) to ventilation (Borg/V(E) slope) also correlated with FIV1 (r = 0.36, P < .02). Beta-blocker therapy improved echocardiographic variables, but not pV(O2). There was no change in PIF or FIV1. There was a significant reduction in FEV 1 after beta-blocker treatment (P < .01). CONCLUSION: Inspiratory flows are impaired in patients with chronic heart failure and correlate with the degree of functional impairment. This may be due to a combination of respiratory muscle weakness and reduced lung compliance. The reduction in inspiratory capacity is not influenced by long-term beta-blockade.

Adrenergic beta-Antagonists↗
PubMed1995

Impairment of lung volumes and respiratory muscle strength in adult patients with growth hormone deficiency.

Little is known of the respiratory function in patients with growth hormone (GH) deficiency. The aim of the present study was to evaluate lung volumes and respiratory muscle strength in patients diagnosed as GH deficient in childhood. Ten patients diagnosed as GH deficient in childhood and ten healthy subjects entered the study. For each subject the evaluation of respiratory function followed the same standard approach, consisting of respiratory muscle strength assessment, recording of flow-volume curves, measurement of static lung volumes and lung diffusing capacity. Both maximal inspiratory and expiratory mouth pressures were decreased in GH deficiency. Vital capacity, N2 functional residual capacity and total lung capacity were significantly reduced when compared to healthy subjects. Conversely, the residual volume and diffusing lung capacity to CO did not show any significant change. No significant change of percentage forced expiratory volume in 1 s/forced vital capacity ratio was observed. The decrease of respiratory mouth pressures was not correlated to the decrease of lung volumes. In conclusion, the results of this study show that adult patients affected with childhood onset GH deficiency suffer from impairment of ventilatory function and a decrease of respiratory muscle pressures, probably due to reduction of respiratory muscle strength.

Adult↗
PubMed1985

Temporal pulmonary function changes in cervical cord injury.

Temporal changes in pulmonary function (PF) in subjects with complete cervical cord transection occur in two stages. The first, extending from the acute to post-acute periods, is characterized by relatively rapid increases in the following: vital, inspiratory, and total lung capacities (VC, IC, and TLC, respectively), and inspiratory and expiratory airflows coupled with decreases in functional residual capacity (FRC). Second stage changes--from the post-acute period on--are more gradual, with both VC increase and FRC decrease continuing while TLC and ventilatory indices remain unchanged. The initial stage appears to be caused in part by functional respiratory muscle return coincident with resolution of inflammation and edema above the injury level. Altered respiratory mechanics also contribute to these early changes and the continuing later changes. Mechanical changes in the lung are probably both decreased compliance (which decreases FRC) and increased airway resistance (which diminishes airflow). Chest wall changes, resulting from returning spinal cord reflexes, affect PF via: (1) increased rib cage stability, leading to a more effective transduction of diaphragmatic displacement into lung volume, and (2) abdominal and expiratory intercostal spasticity, which could limit maximum inspiration. The net effect of these changes, however, may eventually lead to chronic hypoventilation.

Adolescent↗