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At least 19 recordsLinked to original sources
PubMed1993

Prediction equations for maximal voluntary ventilation in non-smoking normal subjects in Madras.

Maximal voluntary ventilation (MVV) was measured in 256 healthy non-smoking adults (132 males, 124 females) aged 15-63 years living in Madras. The mean MVV (+/- SD) in males was 126.7 +/- 31.9 and in females 77.7 +/- 16.4. Regression equations were derived for men and women for predicting maximal voluntary ventilation for adults in South India. MVV in South Indians were similar to those reported for other Indian subjects, but lower than those reported for caucasians.

Adolescent↗
PubMed1983

Influence of exercise on maximal voluntary ventilation and forced expiratory flow at depth.

Four to six subjects performed maximal voluntary ventilation (MVV) and forced expirations during rest, exercise (50, 125, and 200 W), and inhalation of air and CO2 and air at rest while submerged at pressures of 1.45, 2.82, 4.64, and 6.76 atm. Maximal expiratory flow (at 40% of vital capacity) and MVV at rest decreased as exponential functions of gas density, but the decrease was less than in some earlier studies. Independent of pressure, MVV increased by about 10%-17% at the heavier work loads and expiratory flow increased by 27%-48%; the increase in expiratory flow disappeared within 2 min after exercise. Exercise increased end-tidal CO2 tension by up to 9 mmHg. Carbon dioxide inhalation increasing the end-tidal level by up to about 25 mmHg during rest had no effect on MVV and a slight to moderate effect on flow, increasing it by a maximum of 21% at 4.64 atm. The enhancing effect of exercise on MVV and expiratory flow at depth apparently was mainly due to modified autonomic nervous activity reducing pulmonary flow resistance, CO2 accumulation playing an uncertain role, and passive distension of airways playing no role.

Adult↗
PubMed1982

The influence of airway obstruction and respiratory muscle strength on maximal voluntary ventilation in lung disease.

To assess the effects of airway conductance (Gaw) and respiratory muscle strength (RMS) on maximal voluntary ventilation (MVV), we studied 8 normal subjects (N), 8 patients with interstitial lung disease (ILD), and 16 with chronic airflow limitation (CAL). In the patients with ILD, RMS explains 83% of the variance in MVV (p less than 0.005), but Gaw explains none. In the patients with CAL, Gaw and RMS explain, respectively, 65 and 34% of the variance in MVV (p less than 0.02). Considering Gaw and RMS together increases the explained variance to 77% (p less than 0.005). In groups CAL and N combined, Gaw and RMS explain 86% of the variance in MVV, with 71% explained by Gaw and 34% by RMS, which the other variable alone failed to explain (p less than 0.005). When the data are normalized for age, sex, height, and lung volume, the influence of %RMS on %MVV is halved, but remains significant (p less than 0.05). We conclude that RMS is a primary determinant of MVV in patients with ILD, and an important determinant in patients with CAL.

Adult↗
PubMed1982

Respiratory muscle strength and maximal voluntary ventilation in undernourished patients.

To assess the effect of chronic debilitation on respiratory muscle function, we studied 16 poorly nourished (PN) patients without pulmonary disease, and 16 well-nourished (WN) subjects matched for age and sex. Body weight, vital capacity (VC), maximal voluntary ventilation (MVV), and maximal static inspiratory and expiratory pressures (PImax and PEmax) were measured and expressed as percent predicted. Respiratory muscle strength (RMS) was calculated as (% PImax + % PEmax)2. Body weight was 71% predicted in the PN group and 104% in the WN group. The RMS, MVV, and VC were 37%, 41%, and 63%, respectively, of the values in the WN group (p less than 0.001). The 60% reduction in RMS was shared almost equally among inspiratory and expiratory muscles, and PEmax was linearly related to body weight. Because malnutrition reduces both respiratory muscle strength and MVV, it may well impair respiratory muscle capacity to handle increased ventilatory loads in thoracopulmonary disease.

Adolescent↗
PubMed1988

Supine position and sleep loss each reduce prolonged maximal voluntary ventilation.

Because of the prevalence of supine posture and sleep deprivation in both health and disease, we wondered how each of them influences prolonged maximal voluntary ventilation (MVV). Accordingly, we compared 12-second, 1-min, and 10-min isocapnic MVV supine with that measured in the upright posture in 8 healthy subjects. MVV decreased 6-10% supine, independent of test duration (p less than 0.01). Although end-expiratory lung volume was 0.47 liter lower during supine resting breathing (p less than 0.001), end-expiratory lung volumes during short-term MVV maneuvers were identical. To investigate any additional effect on MVV due to sleep loss, 12 healthy subjects performed 12-second, 1-min, and 30-min isocapnic MVV maneuvers in the supine position, either after normal sleep or after a 24-hour sleepless period. Sleep deprivation reduced MVV by 7-14%, again independent of test duration (p less than 0.05). Sleep loss also reduced the ventilation chosen to represent a submaximal (75%) breathing effect (p = 0.05), and it increased subjective ratings of fatigue and confusion (p less than 0.01). We conclude that supination and sleep deprivation together decrease both short- and long-term MVV by nearly 20%, with impairment of supination not caused by lung volume changes, and with the sleep loss effect occurring in tandem with a rise in the subjective assessment of breathing effort.

Adult↗
PubMedDate not supplied

The effects of a 9-week program of aerobic and upper body exercise on the maximal voluntary ventilation of chronic obstructive pulmonary disease patients.

PURPOSE: The purpose of this study was to evaluate the effects of a 9-week exercise program that emphasized aerobic and upper body strength on the maximal voluntary ventilation (MVV) of patients with chronic obstructive pulmonary disease (COPD). An experimental and control group totaling 40 patients with a diagnosis of COPD was studied. METHODS: Experimental group subjects were given a pre- and post-MVV breathing test, a Patient's Attitude Toward Health (PATH) questionnaire, a knowledge of disease questionnaire and a 6-minute walk test. Pre- and post-MVV breathing tests were performed on the control group. Dependent t-test and analysis of covariance were utilized to evaluate the results. RESULTS: Significant differences were found between the pre-test and post-test within the experimental group on MVV results, program attitudes toward health (PATH scores), knowledge level about their disease state after the rehabilitation program, and 6-minute walk distance. There were no significant differences found in the MVV results between the pre-test and post-test for the control group. There was a significant difference when comparing the control group MVV results to the MVV results of the exercise group. CONCLUSIONS: These findings indicate that pulmonary rehabilitation programs can help patients realize improved lung function, improved emotional states, increased knowledge about their disease states, and an increased cardiovascular fitness level. The results of this study suggest a regimen that can improve the quality of life for patients with chronic lung disease.

Aged↗
PubMed1988

Discontinuation of mechanical ventilation.

The vast majority of patients who undergo mechanical ventilation are able to discontinue ventilatory assistance within a few days. Typically, patients who require only short-term mechanical ventilation do not have severe underlying lung disease, and the problem for which they require ventilatory support is most commonly rapidly reversible. In these patients on short-term ventilatory support, parameters of spontaneous ventilatory requirements and respiratory muscle strength, including minute ventilation, maximal voluntary ventilation, vital capacity, and maximal inspiratory pressure, are useful in predicting the success of discontinuation of mechanical ventilation. Ventilatory support can generally be discontinued by a variety of techniques in these patients without the need for weaning from the ventilator per se. The smaller group of patients in whom it is not possible to discontinue mechanical ventilation within less than 7 days comprises individuals who frequently have severe acute or chronic lung disease, multisystem extrapulmonary disease, or neuromuscular disease. After a period of prolonged mechanical ventilatory support, these complicated patients require a process of progressive weaning in which they gradually become able to support spontaneous ventilation. Spontaneous ventilatory parameters do not correlate well with weaning ability in patients on long-term ventilatory support. A systematic and comprehensive approach in which attention is focused on optimizing pulmonary and nonpulmonary factors that affect the weaning process provides the best chance for successful withdrawal of ventilatory support after long-term mechanical ventilation. Inadequate ventilatory drive, respiratory muscle weakness and fatigue, increased work of breathing, excessive CO2 production, and cardiac failure are potential mechanisms that may play a role in inhibiting successful weaning. Adverse factors relevant to each of these mechanisms must be addressed and corrected to whatever extent possible. Studies have not demonstrated the superiority of either classic T-piece weaning or IMV weaning methods in difficult-to-wean patients on long-term ventilatory support. Both techniques may be used successfully as long as all patient variables that may adversely affect weaning ability are corrected or optimized and close care and attention to the details of the weaning process itself are provided.(ABSTRACT TRUNCATED AT 400 WORDS)

Heart Failure↗
PubMed1993

Exertional breathlessness in patients with chronic airflow limitation. The role of lung hyperinflation.

There is considerable intersubject variability in the perceived intensity of breathlessness for a given level of activity among patients with chronic airflow limitation (CAL). To examine possible factors contributing to this variability we compared breathing pattern parameters, dynamic operational lung volumes, and Borg dyspnea ratings in 23 patients with severe CAL and in 10 healthy age-matched normal subjects during cycle ergometry to symptom-limitation. Patients with CAL had significantly (p < 0.01) higher levels of ventilation (% maximal voluntary ventilation) for a given work rate (slope of VE(%MVV)/WR(% pred max) = 1.51 +/- 0.18 versus 0.63 +/- 0.10; mean +/- SEM) and greater dynamic lung hyperinflation (DH) (change [delta] in end-expiratory lung volume [EELVdyn] = +0.31 +/- 0.11 L versus -0.16 +/- 0.22 L). Compared with normal subjects at a standardized VE (30 L/min), the CAL group was more breathless Borg = 4 +/- 1 versus 2 +/- 1, p < 0.01) and hyperinflated (EELVdyn = 75 +/- 3 versus 46 +/- 6% TLC, p < 0.001; end-inspiratory lung volume [EILVdyn] = 85 +/- 3 versus 67 +/- 5% TLC, p < 0.01). Within the CAL group, change in Borg ratings correlated with delta VE(%MVV) (r = 0.77, p < 0.001) and with slope of VE(%MVV)/WR(% pred max) (r = 0.48, p < 0.01). Regression analysis selected delta EILVdyn (or delta inspiratory reserve volume [delta IRVdyn]) from various dynamic ventilatory parameters as the strongest predictor of delta Borg (r = 0.63, p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1984

Maximal ventilation at rest and exercise in patients with chronic pulmonary disease.

74 subjects of different ages: normal children, 19 boys (A) and 7 girls (C) aged between 11 and 15 years; asthmatic boys (n = 7, group B) and girls (n = 7, group D), with similar ages; normal male adult subjects (n = 10, group E) and pulmonary patients with restrictive (n = 8, group G) or obstructive (n = 16, group F) ventilatory impairment, were submitted to measurements of vital capacity (VC), forced expiratory volume in 1 s, (FEV1), maximal voluntary ventilation (MVV), maximal peak expiratory (PEF) and inspiratory (PIF) flows at rest, and two maximal exercise stress tests in which the ventilation at maximal exercise (MEV) were retained. Indirect MVV was obtained by multiplying the FEV1 by 35 and 37.5. The correlation coefficients between MVV and VC, FEV1, PEF and PIF were always as high as r greater than 0.76. (p less than 0.001), with a discrepancy between the calculated and measured MVV. The average ratio MVV/FEV1 always exceeds 39 and is much higher in groups B, C and G. The mean percent values of the ratio MEV/MVV were 0.63 in normal men and 0.74 in normal boys. In patients, this ratio is higher than in adult normals: F = 0.81 and G = 0.88, and is not due to methodological errors, but seems to correspond to several physiological features playing only a role during exercise (MEV). This work shows the difficulty in predicting correctly the MVV at rest and in assessing the ventilatory reserve during maximal exercise in chronic pulmonary patients.

Adolescent↗
PubMed1985

Effect of endurance exercise training on ventilatory function in older individuals.

To evaluate the effect of endurance training on ventilatory function in older individuals, 1) 14 master athletes (MA) [age 63 +/- 2 yr (mean +/- SD); maximum O2 uptake (VO2max) 52.1 +/- 7.9 ml . kg-1 . min-1] were compared with 14 healthy male sedentary controls (CON) (age 63 +/- 3 yr; VO2max of 27.6 +/- 3.4 ml . kg-1 . min-1), and 2) 11 sedentary healthy men and women, age 63 +/- 2 yr, were reevaluated after 12 mo of endurance training that increased their VO2max 25%. MA had a significantly lower ventilatory response to submaximal exercise at the same O2 uptake (VE/VO2) and greater maximal voluntary ventilation (MVV), maximal exercise ventilation (VEmax), and ratio of VEmax to MVV than CON. Except for MVV, all of these parameters improved significantly in the previously sedentary subjects in response to training. Hypercapnic ventilatory response (HCVR) at rest and the ventilatory equivalent for CO2 (VE/VCO2) during submaximal exercise were similar for MA and CON and unaffected by training. We conclude that the increase in VE/VO2 during submaximal exercise observed with aging can be reversed by endurance training, and that after training, previously sedentary older individuals breathe at the same percentage of MVV during maximal exercise as highly trained athletes of similar age.

Aged↗
PubMed1987

Effects of intermittent negative pressure ventilation on respiratory muscle function in patients with severe chronic obstructive pulmonary disease.

The reduced respiratory muscle strength and increased work of breathing in patients with severe chronic obstructive pulmonary disease (COPD) may predispose these patients to the development of respiratory muscle fatigue and consequent respiratory failure. To test the hypothesis that these patients may be experiencing chronic respiratory muscle fatigue, we studied the effects of resting the respiratory muscles in a group of patients with severe COPD. Fifteen stable patients with severe COPD were randomized into study and control groups. In 8 study group patients (Group B), breathing was assisted with a negative pressure ventilator 3 to 6 h daily for 3 consecutive days. The remaining 7 patients served as controls (Group A) and did not receive any intervention. Baseline lung function was evaluated by spirometry and arterial blood gas determinations. Respiratory muscle strength and endurance were evaluated by maximal inspiratory and expiratory pressures (MIP and MEP, respectively) and the maximal duration that isocapnic hyperventilation equal to 50 and 70% of the 12-s maximal voluntary ventilation could be sustained (DSV). Baseline DSV was determined as the best effort of several practice trials. All measurements were repeated on the final day of assisted ventilation approximately 2 to 3 h after its discontinuation. After assisted ventilation, the DSV at 50 and 70% of the maximal voluntary ventilation improved significantly (p less than 0.05). Maximal inspiratory pressure and MEP increased to 114% (p less than 0.05) and 112% (p = 0.05) of baseline values, respectively. Mean arterial PCO2 in the hypercapnic subgroup of Group B patients decreased from 60 mm Hg before to 52 mm Hg after assisted ventilation (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Carbon Dioxide↗
PubMed1988

Impaired exercise tolerance after inferior vena caval interruption.

Four patients were evaluated for persistent dyspnea eight months to four years after inferior vena caval interruption for treatment of pulmonary emboli. Maximal exercise testing with gas-exchange analysis was performed. All patients attained less than 64 percent of predicted maximal oxygen uptake. Peak exercise heart rates were 85 percent or greater of predicted values. Arterial hypoxemia was not observed. The ratio of dead space to tidal volume (VD/VT) decreased with exercise, and the ratios of maximal exercise ventilation to maximal voluntary ventilation (VE/MVV) were less than 67 percent. These results suggest a cardiac rather than a ventilatory limitation to exercise. Inadequate venous blood return to the heart is the likely mechanism for the impaired exercise performances.

Adult↗
PubMed1995

Benefit of selective respiratory muscle training on exercise capacity in patients with chronic congestive heart failure.

BACKGROUND: Diminished respiratory muscle strength and endurance have been demonstrated in patients with heart failure. This may contribute to exertional dyspnea and reduced exercise capacity in these patients. The purpose of this study was to investigate whether selective respiratory muscle training could alleviate dyspnea and improve exercise performance in patients with chronic congestive heart failure. METHODS AND RESULTS: Fourteen patients with chronic heart failure (left ventricular ejection fraction, 22 +/- 9%) were enrolled in a supervised respiratory muscle training program. This consisted of three weekly sessions of isocapnic hyperpnea at maximal sustainable ventilatory capacity, resistive breathing, and strength training. Maximum sustainable ventilatory capacity, maximum voluntary ventilation, maximal inspiratory and expiratory pressures, peak VO2, and the 6-minute walk test were measured before (pre) and after (post) 3 months of training. Eight patients completed the training program. Respiratory muscle endurance was improved with training, as evidenced by increases in maximal sustainable ventilatory capacity (pre, 48.6 +/- 10.7 versus post, 76.9 +/- 14.5 L/min; P < .05) and in maximal voluntary ventilation (pre, 100 +/- 36 versus post, 115 +/- 39 L/min; P < .05). Respiratory muscle strength was also increased with training as maximal inspiratory (pre, 64 +/- 31 versus post, 78 +/- 33 cm, H2O; P < .01) and expiratory (pre, 94 +/- 30 versus post, 133 +/- 53 cm H2O; P < .001) pressures rose. Submaximal and maximal exercise capacity were significantly improved with selective respiratory muscle training as the 6-minute walk (pre, 1101 +/- 351 versus post, 1421 +/- 328 ft; P < .001) and peak exercise VO2 (pre, 11.4 +/- 3.3 versus post, 13.3 +/- 2.7 mL.kg-1.min-1; P < .05) both significantly increased. Dyspnea during activities of daily living was subjectively improved in the majority of trained patients. Dyspnea quantified by the Borg scale was significantly reduced during progressive isocapnic hypernea but not during bicycle exercise. No statistically significant improvement in maximal sustainable ventilatory capacity, maximum voluntary ventilation, maximal inspiratory or expiratory mouth pressures, 6-minute walk, or peak VO2 was observed in the 6 patients who did not complete the training program. CONCLUSIONS: Selective respiratory muscle training improves respiratory muscle endurance and strength, with an enhancement of submaximal and maximal exercise capacity in patients with heart failure. Dyspnea during activities of daily living was subjectively improved in the majority of trained patients.

Adult↗
PubMed1986

Within- and between-day reproducibility of isocapnic cold air challenges in subjects with asthma.

Eight adult subjects with asthma had isocapnic cold air challenges on 4 different days. Three consecutive tests were performed on each visit with functional recovery between tests. Subjects were asked to breathe dry cold air (-20 degrees C) for progressively increasing levels of minute ventilation (7.5, 15, 30, and 60 L/min and maximal voluntary ventilation) until a 20% fall in FEV1 had been reached or when maximal voluntary ventilation was done. FEV1 was assessed between each level. The doses of respiratory heat exchange and minute ventilation causing 10%, 15%, and 20% changes in FEV1 were interpolated from dose-response curves. The within- and between-day 95% confidence intervals based on a single determination on the loge scale varied from +/- 0.32 to 0.59 for the indices derived from respiratory heat exchange. Reproducibility of the between-day results was more satisfactory than for the corresponding within-day assessments. No significant within-day tachyphylaxis was demonstrated for these indices.

Adolescent↗
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↗
PubMed1995

Effects of almitrine on the ventilatory control, breathing pattern and maximal exercise tolerance in hypoxemic patients with chronic obstructive pulmonary disease.

Almitrine bismesylate improves arterial blood gases in patients with chronic obstructive pulmonary disease (COPD), but side effects such as increase of ventilatory drive and dyspnea have been reported in some studies. We studied 18 COPD patients (mean age = 59.1 years; mean FEV1 = 0.92 1; mean PaO2 = 58.6 mmHg) in a double-blind randomized study using placebo or almitrine 50 mg twice a day by mouth, for 60 days. In contrast to the placebo group, 40% of the patients in the almitrine group presented a significant increase in PaO2 and a decrease in P(A-a)O2 > or = 5 mmHg during submaximal exercise after 60 days of treatment. Ventilatory drive and the breathing pattern were measured at rest and during submaximal exercise. Both groups showed high levels of ventilatory drive and a tachypneic breathing pattern before drug treatment and no modification was found 30 and 60 days after treatment. Metabolic, cardiovascular and ventilatory variables were studied during an incremental to maximum exercise symptom-limited test (cycloergometry). Maximal VO2 ranged from 46 to 52% and heart rate from 76 to 78% in relation to the predicted values. The percent ratio of ventilation at maximal exercise to maximal voluntary ventilation at rest ranged from 86 to 94%. These results show that the reduction of ventilatory capacity was the main factor decreasing the aerobic performance of our COPD patients. Maximal exercise tolerance (VO2 max) did not change after almitrine treatment. Negative factors like an increase in neuromuscular drive did not occur, and positive factors like an increase in PaO2 and oxygen transport had no critical influence on exercise performance in our ventilatory-limited COPD patients.

Adult↗