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Results for “Maximal Voluntary Ventilation”

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PubMed1987

Shape of the dose-response curve to cold air inhalation in normal and asthmatic subjects.

Inhalation of cold air at increasing levels of minute ventilation with assessment of bronchomotor tone between each inhalation (dose-response curve) has been used as a method to assess bronchial hyperresponsiveness. However, no information is available on the shape of the obtained dose-response curve, and it is not known if a plateau of response is reached. We investigated this problem in 13 adult asthmatic subjects (PC20 methacholine results varying from 0.04 to 15.2 mg/ml), 5 normal and 2 former asthmatic individuals (PC20 greater than 8 mg/ml). Inhalation dose-response curves were drawn by asking the subjects to inhale dry cold air (-20 degrees C) for 3 min at progressively increasing degrees of ventilation (5, 10, 15, 20, etc., L/min) until maximal voluntary ventilation (MVV) or sufficient bronchoconstriction was reached. FEV1 was assessed after each degree until no further decline was seen. No functional recovery was observed before asking the subject to inhale the next dose of cold air. Maximal falls in FEV1 ranged from 20.7 to 56.5% in the current asthmatic subjects, whereas no significant (less than 10%) changes in FEV1 were obtained in the normal and former asthmatic individuals. Seven to 13 points on the individual dose-response curves were obtained for each current asthmatic subject. Curves were analyzed using the common pharmacologic logistic model. The coefficients of correlation were, in general, highly statistically significant. Curves obtained for the current asthmatic subjects represented a truncated sigmoidal pattern without a plateau. Curves were flat in the normal and former asthmatic individuals.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

Evolution of pulmonary function during an acute exacerbation in hospitalized patients with cystic fibrosis.

Few objective criteria have been validated for serial clinical monitoring in patients with cystic fibrosis (CF) during pulmonary exacerbations. While pulmonary function tests (PFT) are often used to monitor clinical improvement, it is not known which test correlates most closely with clinical improvement. To answer this, we measured routine PFT in 58 patients with CF before, during, and at discharge after 2-3 week hospital admission in 71 episodes of pulmonary exacerbation. Patients with CF were discharged based on clinical, radiological, and laboratory criteria. In general, all PFTs improved at midadmission and improved further by discharge, at which time forced expiratory volume in 1 second (FEV1), forced expiratory flow between 25% and 75% of forced vital capacity (FEF25-75), vital capacity (VC), maximal voluntary ventilation (MVV), and oxygen saturation by pulse oximetry (SPO2) increased. The residual volume to total capacity ratio (RV/TLC) and the slope of phase 3 in the single breath N2 washout curve (SP3 N2) decreased. The change in SP3 N2 was significantly greater than in any other PFT (P < 0.01 vs. VC and FEV1; P < 0.02 vs. RV and P < 0.001 vs. SPO2). A calculated optimal cut-off value for SP3 N2 improvement was significantly more sensitive in identifying patient improvement at discharge than any other pulmonary function test (P = 0.005). We speculate that clinical improvement in patients with CF is closely linked to improved distribution of ventilation.

Acute Disease↗

PubMed2004

An evaluation of standardizing target ventilation for eucapnic voluntary hyperventilation using FEV1.

Athletes are required to provide objective documentation of exercise-induced bronchoconstriction (EIB) to use beta2-agonists during Olympic competition. A positive response to bronchial provocation by eucapnic voluntary hyperventilation (EVH) is considered acceptable confirmation of EIB. Thirty times forced expiratory volume in the first second (FEV1) is recommended as EVH target ventilation (TV), an intensity intended to estimate 85% of maximal voluntary ventilation (MVV). There is a paucity of data examining the accuracy of predicting MVV from FEV1 in elite athletes. The purpose of this study was to evaluate the efficacy of 30 x FEV1 as standardized EVH TV. Maximal minute ventilation during exercise (VEmax) and pulmonary function of 78 elite winter athletes (25 males, 53 females; 25 EIB positive, 53 normal) were analyzed retrospectively. Adequacy and variability of the equation was ascertained by examining the ratio of EVH TV (30 x FEV1) to VEmax. VEmax was 99+/-11% of predicted MVV (35 x FEV1) and was positively related (r=0.85, p < or = 0.05). TV was 88+/-9% of VEmax (range: 64-109). For elite athletes, the high variability in 30 x FEV1 to standardize TV for EVH may result in under-diagnosis for low-end outliers. Since VEmax of elite endurance athletes is typically known (via maximal aerobic testing) we recommend 85% VEmax as a more accurate and reliable method to establish EVH TV for this group; if VEmax is not available, then 85% of measured MVV may be used.

Adult↗

PubMed1994

Effect of theophylline on exercise performance in patients with severe chronic obstructive pulmonary disease.

BACKGROUND: Theophylline is a well known bronchodilator which has been used for more than 50 years in the treatment of obstructive pulmonary diseases. In patients with severe chronic obstructive pulmonary disease whose cardiopulmonary performance is limited by their ventilatory capacity the administration of theophylline may improve exercise performance. METHODS: A randomised, placebo controlled, double blind, crossover trial was conducted in 22 patients with severe but stable disease. The patients (mean age 68 years) were studied before and after one month of placebo and one month of treatment with a sustained release preparation of theophylline administered orally. The theophylline dose was adjusted until a blood level above 55.5 mumol/l was achieved. The two treatments were administered in random order and separated by a two week washout period. After theophylline was administered for one month a mean level of 68.2 mumol/l was achieved. Pulmonary function tests, arterial blood gas measurements, maximal voluntary ventilation (MVV), and an incremental exercise test were performed before (baseline) and at the end of the first and second month of treatment. RESULTS: Pulmonary function tests showed no improvement in the flow parameters but showed an improvement in MVV after treatment with theophylline. Pulmonary gas exchange was improved after theophylline (resting arterial PO2 8.91 v 8.59 kPa, PCO2 5.38 v 5.56 kPa). The incremental exercise study showed improvement in maximal work rate (86.5 v 75.0 watts) and maximal ventilation (VEmax) (46.7 v 43.01/min). The dyspnoea index on maximal effort (VEmax/MVV), anaerobic threshold, and oxygen pulse remained unchanged. Resting and exercise heart rate were higher after theophylline. CONCLUSIONS: Theophylline improved cardiorespiratory performance in these patients with severe chronic obstructive pulmonary disease mainly by increasing the ventilatory capacity.

Aged↗

PubMed1982

Ventilatory endurance in athletes: a family study.

Endurance athletes possess superior ability to sustain high ventilation. However, it remains unknown if this high ventilatory endurance is an effect of training. As one approach to this question, we compared the breathing endurance of eight distance runners with that of eight of their siblings who were untrained. In two separate tests involving seated isocapnic hyperpnea, the athletes had greater ability to sustain high VE than did their brothers and sisters. In the first test, VE was voluntarily incremented by 30 l/min each 4 min. Before exhaustion, the athletes reached a VE that was a significantly greater fraction of their 12-s maximal voluntary ventilation than did the untrained siblings (75 vs. 62%; P less than 0.01). In the second test, 80% of the 12-s MVV was sustained until exhaustion. Endurance times for the athletes doubled those of the untrained siblings (7 vs. 3 min; P less than 0.05). The failure of elevated ventilatory endurance to occur in family clusters suggests that it may primarily result from training.

Adolescent↗

PubMed1988

Changes in respiratory muscle function after neostigmine injection in patients with myasthenia gravis.

In sixteen patients with myasthenia gravis, the weakness of respiratory muscles, especially of expiratory, caused some disturbances in lung function. Thirty minutes after injection of neostigmine, general improvement of muscle function was accompanied by an increase of strength and endurance of respiratory muscles. The mean value of maximal inspiratory mouth pressure (PImax) increased by 33%, maximal expiratory mouth pressure (PEmax) by 23.5% and maximal voluntary ventilation (MVV) by 21%. As a consequence of these changes amelioration of lung function indices was found, vital capacity increasing on average by 13% and residual volume decreasing by 12.5%. We concluded that patients with generalized myasthenia gravis have disturbances in lung function which may be partially improved by neostigmine injection or other anticholinesterase agents.

Adult↗

PubMed1982

Variation among normal persons in short-term ventilatory capacity.

Among individuals of comparable size with normal lungs, short-term breathing capacity varies widely for unknown reasons. If the velocity of ventilatory muscle contraction limits airflow, then persons with a high proportion of fast twitch fibers in the ventilatory muscles should have large ventilatory capacities. As one test of this hypothesis, we correlated ventilatory capacity with vertical jump, an index of leg and thus of diaphragmatic muscle fiber composition. We found significant positive correlations between vertical jump and the 12-second maximal voluntary ventilation in both women (n = 19, r = 0.6; p less than 0.01) and men (n = 25; r = + 0.4; p = 0.06). Both correlations were independent of body weight or vital capacity. These results are consistent with the hypothesis that short-term ventilatory capacity is influenced by the contractile characteristics of the ventilatory muscles.

Adult↗

PubMed1983

Blood lactate and respiratory muscle fatigue in patients with chronic airways obstruction.

Blood lactate concentrations were measured in five patients with chronic airways obstruction after 10 minutes' sustained maximal voluntary ventilation (SMVV) with end-tidal carbon dioxide tension kept constant and after a 12-minute walk. No patient showed a significant rise in blood lactate after SMVV but all showed evidence of low-frequency fatigue of the sternomastoid muscle. After a 12-minute walk three patients showed a significant rise in blood lactate and two of them also had evidence of low-frequency fatigue of the sternomastoid muscle. The absence of a rise in blood lactate after SMVV may be due to the fact that in patients with chronic airways obstruction ventilation is limited by airflow obstruction to a level where only a small muscle mass is used, or where the aerobic capacity of the respiratory muscles is not exceeded.

Aged↗

PubMed1992

Respiratory function in multiple sclerosis. Utility of clinical assessment of respiratory muscle function.

PURPOSE: The aim of this study was to assess the utility of clinical assessment of respiratory muscle weakness in MS. PATIENTS AND METHODS: We studied 40 MS patients who performed pulmonary function tests using standard procedures and measures of respiratory muscle strength. Descriptive clinical indices included a history of detailed neurologic findings, including upper and lower extremity weakness, cerebellar signs, and evidence of cerebral lesions and other clinical signs including dependence in activities of daily living, shortness of breath, weak voice, dysarthria and dysphagia. We devised an index comprised of four clinical signs: the patient's report of difficulty in clearing pulmonary secretions and his report of a weakened cough, the examiner's observation of the patient's cough, and ability to count on a single exhalation. RESULTS: Mean values of TLC (95 percent +/- 14) VC (91 percent +/- 19), and RV (106 percent +/- 34) were normal. By contrast, MVV (68 percent +/- 20), PImax (74 percent +/- 27) and PEmax (51 percent +/- 22) were decreased. Stepwise multiple regression indicated that the best single predictor of expiratory muscle weakness was the index score; the combination of index score, upper extremity weakness, and maximal voluntary ventilation accounted for 60 percent of the variance in PEmax. CONCLUSION: We conclude that clinical assessment is a better predictor of respiratory muscle weakness than spirometry and that a systematic clinical assessment supplemented by respiratory muscle assessment and MVV can uncover subtle respiratory muscle weakness in patients with MS.

Adult↗

PubMed1988

Ventilatory muscle training in the elderly.

To test the hypothesis that declining ventilatory function in the elderly impairs exercise capacity, we tested maximal exercise capacity and ventilatory function before and after a program of ventilatory muscle training in 25 elderly subjects (ages 65-75 yr). Ventilatory muscle training was performed by means of isocapnic hyperpnea for 30 min/day, 4 days/wk for 8 wk. Before and after the training, we measured maximal exercise capacity by means of an incremental exercise test (IET) and ventilatory muscle endurance by means of the maximum sustained ventilatory capacity (MSVC). Ratings of perceived exercise (RPE) for breathlessness and leg effort were evaluated each minute by means of a modified Borg scale during both the IET and a 12-min single-stage exercise test (SST) performed at approximately 70% of the maximal exercise capacity. The trained group showed a significant increase in the MSVC, from 71.9 +/- 26.4 to 86.9 +/- 20.9 l/min (P less than 0.01), whereas the control group showed no change (66.3 +/- 22.5 to 65.1 +/- 22.1 l/min). In addition, the maximal voluntary ventilation increased in the trained group, from 115 +/- 41 to 135 +/- 36 l/min (P less than 0.01). Neither the trained nor the control group showed an increase in maximum O2 uptake, maximum CO2 consumption, or maximum minute ventilation during the IET. Evaluation of the RPE during both the IET and SST showed that although there was a small decrease in RPE for breathing and leg discomfort, changes between the control and treated groups were similar.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1978

Cardiac arrhythmias during routine tests of pulmonary function in patients with chronic obstruction of airways.

We studied the frequency of cardiac arrhythmias during routine tests of pulmonary function by using continuous electrocardiographic recording and a computerized method to quantitate arrhythmias. A total of 150 patients with chronic obstruction of airways were studied before, during, and after routine tests of pulmonary function performed before and after intermittent positive-pressure breathing (IPPB) with a bronchodilator aerosol. The only significant (P less than 0.01) change was an increased frequency of atrial premature beats during tests of pulmonary function. Spirometric studies, maximal voluntary ventilation, and IPPB with a bronchodilator aerosol were equally likely to induce atrial premature beats. Routine tests of pulmonary function represent an additional causal factor in producing arrhythmias in patients with obstruction of airways, although no clinical consequences were evident in the course of the study.

Adolescent↗

PubMedDate not supplied

Ventilatory capacity among highland Bods: a possible adaptive mechanism at high altitude.

Ventilatory capacity (forced vital capacity, forced expiratory volume and maximal voluntary ventilation) among Highland Bods (3514 m altitude) was higher than in an ethnically similar population residing at a lower altitude in Kulu Valley (1500--2200 m). Increased ventilatory capacity appears to have developed among native highlanders as a consequence of a biological response to high altitude. Numerous factors such as low oxygen pressure, increased work-load and minimal air pollution may explain these findings.

Adolescent↗

PubMed1993

[Changes in the physical characteristics of the lung can account for the improvement observed after ultrafiltration in patients with moderate heart failure].

Ultrafiltration improves the clinical condition of patients with moderate congestive heart failure. Ultrafiltration (1895 +/- 120 ml of plasma water, rate 600 ml/h, veno-venous bypass) was performed in 30 patients with moderate congestive heart failure in stable clinical conditions. The effects of ultrafiltration were assessed through pulmonary function and cardiopulmonary exercise tests performed before and 30 days after the procedure. Vital capacity, forced expiratory volume (1 s) and maximal voluntary ventilation improved as improved exercise performance (increase in oxygen consumption at peak exercise and at anaerobic threshold). Tidal volume at anaerobic threshold and at peak exercise increased by 10% with no changes in respiratory rate. This suggests that ultrafiltration induces changes at the physical characteristics of the lungs probably related to changes in lung water content.

Aged↗

PubMed2007

Ventilatory and metabolic demands during aggressive physical restraint in healthy adults.

We investigated ventilatory and metabolic demands in healthy adults when placed in the prone maximal restraint position (PMRP), i.e., hogtie restraint. Maximal voluntary ventilation (MVV) was measured in seated subjects (n=30), in the PMRP, and when prone with up to 90.1 or 102.3 kg of weight on the back. MVV with the heaviest weight was 70% of the seated MVV (122+/-28 and 156+/-38 L/min, respectively; p<0.001). Also, subjects (n=27) were placed in the PMRP and struggled vigorously for 60 sec. During the restrained struggle, ventilatory function (V(E)/ MVV) was 44% of MVV in the resting PMRP. While prone with up to 90.1 or 102.3 kg on the back, the decrease in MVV was of no clinical importance in these subjects. Also, while maximally struggling in the PMRP, V(E) was still adequate to supply the ventilatory needs.

Adult↗

PubMed1976

Effect of the Milwaukee brace on vital and ventilatory capacity of scoliotic patients.

The vital capacity (VC) and the maximal voluntary ventilation (MVV) were studied in 29 patients with scoliosis (predominantly idiopathic). The results obtained confirmed earlier observations that scoliotic patients have decreased VC and MVV. The immediate effect of the application of the Milwaukee brace was a slight though statistically significant decrease in MV, whereas there was no significant effect on VC. Treatment with the Milwaukee brace for a mean period of 15 months did not appreciably influence the VC or MVV, as a percentage of the predicted normal values of the patients, when measured without the brace applied.

Adolescent↗

PubMed2001

Chest mechanics in morbidly obese non-hypoventilated patients.

Seventy-seven patients with morbid obesity, body mass index (BMI) 40-69.9 kg m(-2), who were candidates for gastroplasty, were studied in our laboratory as part of a pre-operative survey. They had no complaints other than obesity and were not cyanotic. A group of 28 lean subjects (BMI 20-29.8 kg m(-2)) who were candidates for abdominal surgery, without any respiratory complaint, were included as controls. For each patient a pulmonary function test was performed, measuring slow vital capacity with expiratory residual volume (ERV), forced vital capacity (flow/volume) and maximal voluntary ventilation (MVV). In obese patients the MVV is reduced as BMI increases. This results in the reduction of expiratory flows and volumes. Forced expiratory volume in 1 sec (FEV1) is reduced in proportion to the FVC reduction and is related to MVV. It is suggested that the main consequence of the burden of the chest wall by increased adipose mass is a reduction in its compliance, making inspiration increasingly difficult, and resulting in lower static volumes and flows.

Adult↗

PubMed1982

Respiratory muscle fatigue after marathon running.

Respiratory muscle fatigue has been demonstrated in the laboratory as well as in pathological states, but whether it occurs in healthy individuals under physiological conditions is unknown. To determine whether fatigue of the respiratory muscles may develop with endurance exercise, we measured spirometry and respiratory muscle strength and endurance in four runners before and after completion of a marathon race (42.2 km). Strength was assessed by measuring maximal inspiratory (PImax) and expiratory (PEmax) pressures and transdiaphragmatic pressure during inspiratory capacity (PdiIC); endurance was determined by measuring maximal voluntary ventilation (MVV). After marathon running (mean time, 3 h 24 min) there was no change in forced vital capacity, inspiratory capacity, or flow rates from prerace values. Decreases were observed between pre- and postrace PImax (165.8 +/- 11.0 vs. 138.5 +/- 7.6 cmH2O; P less than 0.01) PEmax (240.0 +/- 20.4 vs. 173.0 +/- 22.6 cmH2O; P less than 0.05), PdiIC (78.8 +/- 11.6 vs. 63.3 +/- 7.0 cmH2O; P less than 0.10), and MVV (178 +/- 24.2 vs. 161.2 +/- 23.2 l/min; P less than 0.005). The decrements in respiratory muscle strength and endurance suggest the development of respiratory muscle fatigue after marathon running.

Adult↗

PubMed1997

Exercise performance of Tibetan and Han adolescents at altitudes of 3,417 and 4,300 m.

The difference was studied between O2 transport in lifelong Tibetan adolescents and in newcomer Han adolescents acclimatized to high altitude. We measured minute ventilation, maximal O2 uptake, maximal cardiac output, and arterial O2 saturation during maximal exercise, using the incremental exercise technique, at altitudes of 3,417 and 4,300 m. The groups were well matched for age, height, and nutritional status. The Tibetans had been living at the altitudes for a longer period than the Hans (14.5 +/- 0.2 vs. 7.8 +/- 0.8 yr at 3,417 m, P < 0.01; and 14.7 +/- 0.3 vs. 5.3 +/- 0.7 yr at 4,300 m, P < 0.01, respectively). At rest, Tibetans had significantly greater vital capacity and maximal voluntary ventilation than the Hans at both altitudes. At maximal exercise, Tibetans compared with Hans had higher maximal O2 uptake (42.2 +/- 1.7 vs. 36.7 +/- 1.2 ml . min-1 . kg-1 at 3,417 m, P < 0.01; and 36.8 +/- 1.9 vs. 30.0 +/- 1. 4 ml . min-1 . kg-1 at 4,300 m, P < 0.01, respectively) and greater maximal cardiac output (12.8 +/- 0.3 vs. 11.4 +/- 0.2 l/min at 3,417 m, P < 0.01; 11.5 +/- 0.5 vs. 10.0 +/- 0.5 l/min at 4,300 m, P < 0. 05, respectively). Although the differences in arterial O2 saturation between Tibetans and Hans were not significant at rest and during mild exercise, the differences became greater with increases in exercise workload at both altitudes. We concluded that exposure to high altitude from birth to adolescence resulted in an efficient O2 transport and a greater aerobic exercise performance that may reflect a successful adaptation to life at high altitude.

Acclimatization↗