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Inspiratory muscle training in a patient with left ventricular assist device.

The use of mechanical assist devices as a 'bridge' to cardiac transplantation, as a "bridge" to recovery, or as a destination therapy in end-stage heart failure, is increasing. Studies of different modes of rehabilitation in this population are lacking. We report the benefits of inspiratory muscle training on the exercise capacity and quality of life in the recipient of a left ventricular assist device.

Blood Pressure↗
PubMed1990

[Influence of fetal position on respiratory function and its modification by epidural anesthesia in supine pregnant women].

We investigated the influence of fetal position on respiratory function and its modification by epidural anesthesia in supine pregnant women. We found that supine pregnant women in whom the fetus was in the right occipital anterior position (ROA) had lower inspiratory reserve volume (IRV) and vital capacity (VC) than controls in whom the fetus was in the left occipital anterior position (LOA). When the analgesic level was up to Th7 or lower, epidural anesthesia increased the VC of women with a ROA fetus and also increased IRV. With higher analgesic levels up to Th4-Th6, tidal volume (TV) and VC increased independently of fetal position. We speculate that the pressure caused by the ROA fetus on thorax of the mother is stronger and that after epidural anesthesia this pressure decreases even though the analgesic level is low, and with the analgesic level up to Th4-Th6, the level used for Cesarean section, the displacement of the uterus makes respiration during rest easier regardless of fetal position.

Anesthesia, Epidural↗
PubMed1989

[Characteristics of inspiratory flow-volume curves in children with bronchial asthma and patients with cystic fibrosis].

The characteristics of the inspiratory and expiratory flow-volume curves were measured in 77 children with bronchial asthma and 30 patients with cystic fibrosis (CF) in comparison with 19 healthy children. The aim was to explore how for children with lung diseases fulfil the physiological conditions to generate sufficient flow for optimal use of "breath actuated inhalation devices" such as the Spinhaler, Rotahaler, Turbuhaler and Diskhaler. No correlation was found between the values of inspiratory flow-volume curves and conventional lung function parameters either in healthy children or in those with lung diseases. The majority of the patients (78.6%) showed a maximal inspiratory flow, at 50% of vital capacity, (MIF50) of more than 1 l/sec, irrespective of the type of functional disorder (pulmonary hyperinflation, bronchial obstruction or both). The remaining patients (21.4%), comprising mainly patients with CF, did not reach this limit. The flows needed for correct use of the different inhalation devices vary greatly (0.4-1.6 l/sec) and the criterion of a flow lower than 1 l/sec is only fulfilled by the Turbuhaler (0.4 l/sec), the Rotahaler (0.65 l/sec) and the Diskhaler (0.8 l/sec). In contrast, the Spinhaler needs a flow of at least 1.6 l/sec. For practical purposes it seems that an MIF50 of more than 1 l/sec could be used as criterion in the indication for such inhalation devices.

Adolescent↗
PubMed1987

[Functional and diagnostic significance of a study of respiratory regulation in patients with chronic nonspecific lung diseases].

Respiratory regulation at rest and under the influence of increasing hypercapnia was investigated in patients with chronic nonspecific pulmonary diseases (CNPD) with restrictive and obstructive types of lung ventilation capacity disorder. An increase in the inspiratory activity of the central mechanisms of respiratory regulation was revealed even at the early stages of disease. The determination of this type of activity in comparison with respiratory pattern parameters could be of diagnostic value. CNPD patients with congenital immunopathies (Kartagener-Sievert syndrome, CNPD with alpha 1 antitrypsin deficiency) demonstrated concomitant respiratory regulation disorders in the form of low inspiratory activity in response to hypercapnia suggesting a complicated course of disease in these patients.

Adolescent↗
PubMed1995

Weaning chronically critically ill adults from mechanical ventilatory support: a descriptive study.

BACKGROUND: Ventilator-dependent patients average 11,419 daily in US acute care hospitals. OBJECTIVE: To describe the process of ventilatory weaning among chronically critically ill adults. METHODS A retrospective survey was used to study ventilator-dependent adults enrolled in a larger randomized study. Patients records were used to obtain duration of mechanical ventilatory support, success of weaning, serum albumin level, left ventricular function, number of drugs used to treat heart failure, and 24-hour fluid balance. Data were collected on admission to the intensive care unit; 24 hours after initiation of mechanical ventilation; and 7 days before, and on the day of, weaning status determination. RESULTS: Of 174 subjects, 120 were weaned from mechanical ventilation. There were no differences in maximum inspiratory pressure, minute ventilation, or ventilatory capacity between successful and unsuccessful candidates. There were differences in serum albumin level, rapid shallow breathing index, fraction of inspired oxygen, and 24-hour fluid balance. Among subjects who were weaned, the duration of mechanical ventilation was significantly longer in those with left ventricular dysfunction (n = 53; 29.1 +/- 25.2 days) than in those with normal left ventricular function (n = 67; 21.1 +/- 18.1 days). Subjects who were weaned received a greater number of drugs to treat heart failure (1.46 +/- 1.24) than did those who were not (0.77 +/- 1.04). CONCLUSIONS Many weaning parameters do not differentiate patients able to be weaned from those who are unable. The presence of left ventricular dysfunction, number of drugs used to treat heart failure, serum albumin level, and 24-hour fluid balance were associated with weaning success and/or duration of mechanical ventilation in adults requiring prolonged mechanical ventilation.

Adolescent↗
PubMed1999

Inspiratory flow-volume curve in snoring patients with and without obstructive sleep apnea.

We analyzed the flow-volume curves of 50 patients with complaints of snoring and daytime sleepiness in treatment at the Pneumology Unit of the University Hospital of Brasília. The total group was divided into snorers without obstructive sleep apnea (OSA) (N = 19) and snorers with OSA (N = 31); the patients with OSA were subdivided into two groups according to the apnea/hypopnea index (AHI): AHI < 20/h (N = 14) and AHI > 20/h (N = 17). The control group (N = 10) consisted of nonsmoking subjects without complaints of snoring, daytime sleepiness or pulmonary diseases. The population studied (control and patients) consisted of males of similar age, height and body mass index (BMI); spirometric data were also similar in the four groups. There was no significative difference in the ratio of forced expiratory and inspiratory flows (FEF50%/FIF50%) in any group: control. 0.89; snorers, 1.11; snorers with OSA (AHI < 20/h), 1.42, and snorers with OSA (AHI > 20/h), 1.64. The FIF at 50% of vital capacity (FIF50%) of snoring patients with or without OSA was lower than the FIF50% of the control group (P < 0.05): snorers 4.30 l/s; snorers with OSA (AHI < 20/h) 3.69 l/s; snorers with OSA (AHI > 20/h) 3.17 l/s and control group 5.48 l/s. The FIF50% of patients with severe OSA (AHI > 20/h) was lower than the FIF50% of snorers without OSA (P < 0.05): 3.17 l/s and 4.30 l/s, respectively. We conclude that 1) the FEF50%/FIF50% ratio is not useful for predicting OSA, and 2) FIF50% is decreased in snoring patients with and without OSA, suggesting that these patients have increased upper airway resistance (UAR).

Humans↗
PubMed1991

Pulmonary function of preeclamptic women receiving intravenous magnesium sulfate seizure prophylaxis.

Pulmonary function was studied in ten preeclamptic women in labor (mean gestational age 38.1 +/- 0.9 weeks measured from the last menstrual period) receiving continuous intravenous (IV) infusions of magnesium sulfate. Baseline maximal inspiratory pressure, maximal expiratory pressure, functional vital capacity, and forced expiratory volume at 1 second were measured immediately before a 6-g IV loading dose of magnesium sulfate and 2 hours after the initiation of a continuous 2-g/hour infusion of magnesium sulfate. Serum magnesium levels were measured at the same time pulmonary function tests were performed. All values are reported as the mean +/- standard deviation. The maximal inspiratory pressure, an indicator of generalized respiratory muscle weakness, decreased from a baseline value of 26.2 +/- 7.7 to 19.4 +/- 6.3 cm H2O (P less than .05). The maximal expiratory pressure, an indicator of expiratory muscle strength, decreased from a baseline value of 30.6 +/- 9.2 to 25.2 +/- 7.1 cm H2O (P less than .005). The functional vital capacity decreased from a baseline value of 3.37 +/- 0.49 to 3.19 +/- 0.73 L, and the forced expiratory volume at 1 second decreased from a baseline value of 2.61 +/- 0.58 to 2.36 +/- 0.68 L at 2 hours (P less than .05). The mean serum magnesium level was 1.7 +/- 0.2 mg/dL before the administration of the IV loading dose and 4.51 +/- 0.67 mg/dL 2 hours after initiation of the continuous infusion. Our results demonstrate a significant decrease in pulmonary function tests in term preeclamptic patients receiving magnesium sulfate for seizure prophylaxis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1998

The tension-time index and the frequency/tidal volume ratio are the major pathophysiologic determinants of weaning failure and success.

We have previously shown (Am. J. Respir. Crit. Care Med. 1995;152:1248-1255) that in patients needing mechanical ventilation, the load imposed on the inspiratory muscles is excessive relative to their neuromuscular capacity. We have therefore hypothesized that weaning failure may occur because at the time of the trial of spontaneous breathing there is insufficient reduction of the inspiratory load. We therefore prospectively studied patients who initially had failed to wean from mechanical ventilation (F) but had successful weaning (S) on a later occasion. Compared with S, during F patients had greater intrinsic positive end-expiratory pressure (6. 10 +/- 2.45 versus 3.83 +/- 2.69 cm H2O), dynamic hyperinflation (327 +/- 180 versus 213 +/- 175 ml), total resistance (Rmax, 14.14 +/- 4.95 versus 11.19 +/- 4.01 cm H2O/L/s), ratio of mean to maximum inspiratory pressure (0.46 +/- 0.1 versus 0.31 +/- 0.08), tension time index (TTI, 0.162 +/- 0.032 versus 0.102 +/- 0.023) and power (315 +/- 153 versus 215 +/- 75 cm H2O x L/min), less maximum inspiratory pressure (42.3 +/- 12.7 versus 53.8 +/- 15.1 cm H2O), and a breathing pattern that was more rapid and shallow (ratio of frequency to tidal volume, f/VT 98 +/- 38 versus 62 +/- 21 breaths/min/L). To clarify on pathophysiologic grounds what determines inability to wean from mechanical ventilation, we performed multiple logistic regression analysis with the weaning outcome as the dependent variable. The TTI and the f/VT ratio were the only significant variables in the model. We conclude that the TTI and the f/VT are the major pathophysiologic determinants underlying the transition from weaning failure to weaning success.

Adult↗
PubMed2004

Inspiratory muscle training using an incremental endurance test alleviates dyspnea and improves functional status in patients with chronic heart failure.

BACKGROUND: The benefits of inspiratory muscle training (IMT) in patients with chronic heart failure (CHF) have been inadequately studied. DESIGN AND METHODS: Using a prospective, age and sex-matched controlled study, we investigated 35 patients with moderate to severe CHF (NYHA class II-III and left ventricular ejection fraction 24.4+/-1.3% [mean+/-SEM]). An incremental respiratory endurance test using a fixed respiratory workload was provided by software with an electronic mouth pressure manometer interfaced with a computer. The training group (n=20) exercised at 60% of individual sustained maximal inspiratory pressure (SMIP) and the control group (n=15) at 15% of SMIP. All patients exercised three times weekly for 10 weeks. Pulmonary function, exercise capacity, dyspnea and quality of life were assessed, pre- and post-training. RESULTS: The training group significantly increased both maximum inspiratory pressure (Pimax), (111+/-6.8 versus 83+/-5.7 cmH2O, P<0.001), and SMIP (527822+/-51358 versus 367360+/-41111 cmH2O/sec x 10(-1), P<0.001). Peak VO2 increased after training (17.8+/-1.2 versus 15.4+/-0.9 ml/kg/min, P<0.005), as did the six-minute walking distance (433+/-16 versus 367+/-22 meters, P<0.001). Perceived dyspnea assessed using the Borg scale was reduced for both the treadmill (12.7+/-0.57 versus 14.2+/-0.48, P<0.005) and the walking (9+/-0.48 versus 10.5+/-0.67, P<0.005) exercise tests and the quality of life score was also improved (21.1+/-3.5 versus 25.2+/-4, P<0.01). Resting heart rate was significantly reduced with training (77+/-3.3 versus 80+/-3 beats/min, P<0.05). The control group significantly increased Pimax (86.6+/-6.3 versus 78.4+/-6.9 cmH2O, P<0.05), but decreased SMIP (274972+/-32399 versus 204661+/-37184 cmH2O/sec x 10(1), P<0.005). No other significant effect on exercise capacity, heart rate, dyspnea, or quality of life was observed in this group. CONCLUSION: Inspiratory muscle training using an incremental endurance test, successfully increases both inspiratory strength and endurance, alleviates dyspnea and improves functional status in CHF.

Breathing Exercises↗
PubMed1998

Use of mouth pressure twitches induced by cervical magnetic stimulation to assess voluntary activation of the diaphragm.

There is a need for a simple method to assess the adequacy of diaphragm activation during voluntary inspiratory efforts in patients with suspected respiratory muscle weakness. We have compared mouth (Pmo,t), oesophageal (Poes,t) and transdiaphragmatic (Pdi,t) twitch pressure elicited by cervical magnetic stimulation (CMS) in five normal men (mean (SD) age 32.2 (1.8) yrs) on two separate study days. Single magnetic stimuli were delivered at functional residual capacity during relaxation and during graded voluntary inspiratory efforts against a closed airway. As voluntary-effort transdiaphragmatic and oesophageal pressure increased, Pdi,t and Poes,t decreased linearly (r range, respectively, 0.82-0.98 and 0.87-0.95). During relaxation, Pmo,t was unreliable due to the poor transmission of intrathoracic pressure, but during inspiratory efforts, the relation between voluntary mouth pressure and Pmo,t was also linear (r range 0.84-0.95). On average, our subjects voluntarily generated 99, 100 and 102% of the maximum transdiaphragmatic, oesophageal and mouth pressures predicted by the respective linear regression equations. Pmo,t was correlated to both Poes,t and Pdi,t during inspiratory efforts, but not during relaxation. These studies confirm that twitch pressures induced by CMS during inspiratory efforts can be assessed at the mouth in normal subjects, providing a simple and non-invasive technique for assessing diaphragm activation during voluntary inspiratory efforts. Potentially, this technique could be made more sensitive and accurate and applied to detect submaximal efforts in patients.

Adult↗
PubMed2003

Low-birth-weight neonates exhibit a physiological set-point to regulate CO2: an untapped potential to minimize volutrauma-associated lung injury.

The objective of this article is to determine whether low-birth-weight (LBW) infants have the capacity to modulate minute ventilation to achieve a CO (2) set-point within ranges acceptable to clinicians during a procedure designed to identify the best dynamic compliance loops. By using dynamic flow-loop mechanics, we performed a prospective stepwise reduction of tidal volume (by reduction of peak inspiratory pressure, keeping end-expiratory pressure constant), in a group of LBW infants to identify the steepest slope of the dynamic flow-loop. We used flow-synchronized, assist-control mechanical ventilation with termination sensitivity set at 5%. Vital signs and blood gases were assessed every 15 minutes at each stepped-pressure change during the first hour after enrollment and after 12 hours, to evaluate oxygenation and ventilation. Peak inspiratory pressure (PIP) was selected at the lowest level that achieved target range blood gases. The acute reduction of PIP and the resulting lower tidal volume was initially associated with an increase in the spontaneous respiratory rate in the first hour that also was associated with a significant decrease in patient-selected inspiration time. After 12 hours, the spontaneous respiratory rate returned to baseline; the peak PaCO(2) was 43.8 +/- 2.03 (mean +/- SEM). LBW infants have the capacity to alter respiratory rate to change minute ventilation in response to a reduction of tidal volume created by lowering the PIP. Using this model of endogenous CO(2) challenge in ventilated infants, we conclude that LBW neonates have the capacity to select a CO(2) set-point. This approach suggests an important avenue through which a clinician can minimize volutrauma through a reduction of PIP and use of expiratory trigger to limit excessive PIP and an overall lower mean airway pressure.

Adaptation, Physiological↗
PubMed1999

Effects of resistive breathing on exercise capacity and diaphragm function in patients with ischaemic heart disease.

BACKGROUND: Muscle weakness has been suggested to result from the deconditioning that accompanies decreased activity levels in chronic cardiopulmonary diseases. The benefits of standard exercise programmes on exercise capacity and muscular strength in disease and health are well documented and exercise capacity is a significant predictor of survival in patients with chronic heart failure (CHF). Selective respiratory muscle training has been shown to improve exercise tolerance in CHF and such observations have been cited to support the suggestion that respiratory muscle weakness contributes to a reduced exercise capacity (despite biopsies showing the metabolic profile of a well trained muscle). AIMS: This study aimed to determine the effects of selective inspiratory muscle training on patients with chronic coronary artery disease to establish if an improved exercise capacity can be obtained in patients that are not limited in their daily activities. METHODS: Nine male patients performed three exercise tests (with respiratory and diaphragm function assessed before the third test) then undertook a 4-week programme of inspiratory muscle training. Exercise tolerance, respiratory and diaphragmatic function were re-assessed after training. RESULTS: Exercise capacity improved from 812+/-42 to 864+/-49 s, P<0.05, and velocity of diaphragm shortening increased (during quiet breathing from 12.8+/-1.6 to 19.4+/-1.1 mm s(-1), P<0.005, and sniffing from 71.9+/-9.4 to 110.0+/-12.3 mm s(-1), P<0.005). In addition, five from nine patients were stopped by breathlessness before training; whereas only one patient was stopped by breathlessness after training. CONCLUSION: The major findings in this study were that a non-intensive 4-week training programme of resistive breathing in patients with chronic coronary artery disease led to an increase in exercise capacity and a decrease in dyspnoea when assessed by symptom limited exercise testing. These changes were associated with significant increases in the velocity of diaphragmatic excursions during quiet breathing and sniffing. Patients that exhibited small diaphragmatic excursions during quiet breathing were most likely to improve their exercise capacity after the training programme. However, the inspiratory muscle-training programme was not associated with any significant changes in respiratory mechanics when peak flow rate, forced expiratory volume and forced vital capacity were measured. The resistive breathing programme used here resulted in a significant increase in the velocity of diaphragm movement during quiet breathing and sniffing. In other skeletal muscles, speed of contraction can be determined by the relative proportion of fibre types and muscle length (Jones, Round, Skeletal Muscle in Health and Disease. Manchester: University Press, 1990). The intensity of the training programme used here, however, is unlikely to significantly alter muscle morphology or biochemistry. Short-term training studies have shown that there can be increases in strength and velocity of shortening that do not relate to changes in muscle biochemistry or morphology. These changes are attributed to the neural adaptations that occur early in training (Northridge et al., Br. Heart J. 1990; 64: 313-316). Independent of the mechanisms involved, this small, uncontrolled study suggests that inspiratory muscle training may improve exercise capacity, diaphragm function and symptoms of breathlessness in patients with chronic coronary artery disease even in the absence of heart failure.

Aged↗
PubMed1976

Effect of aerosolized isoproterenol on resting myogenic tone in normals.

The effects of aerosolized isoproterenol on expiratory (exp) and inspiratory (insp) conductance (Gaw), maximal exp and insp flow (VEmax and VImax), and static elastic recoil pressure (Pst) were measured in 12 normals. Both exp and insp Gaw increased throughout the vital capacity (37% at 50% VC; P less than 0.01). VEmax increased only at 50% VC (9%; P less than 0.01). VImax and Pst did not change. Accordingly, a dichotomy existed between the Gaw and Vmax changes during both exp and insp. We do not attribute this dichotomy to loss of driving pressure or to volume-time-dependent behavior of airway tone. We interpret the increased exp and insp Gaw to indicate isoproterenol deposition within and bronchodilatation of larger central airways (trachea, main stem, lobar, segmental). Since insp Gaw increased and VImax did not, we conclude that the caliber of these central airways is not the exclusive deteminant of VImax, that the caliber of some more distal airways (subsegmental and beyond) did not change, and that these airways are important determinants of VImax. We conclude that non-uniform distribution of isoproterenol could account for the Gaw-Vmax dichotomy during inspiration, and that such non-uniform distribution coupled with resultant increased compliance and compressibility of the downstream segment could account for the Faw-Vmax dichotomy during expiration.

Adult↗
PubMed1995

[Measurement of the reserve function of inspiratory muscle and its clinical significance].

The principles of measuring inspiratory muscle tension-time index (TTim) and the ratio of the works of inspiration over the maximal works of inspiration (Wi/Wi(max)) were investigated and their formulae were deduced, i.e. TTim = (Pi x Ti)/(MIP x Ttot) and Wi/Wi(max) = (Pi x VT)/(MIP x IC). The importance of the inspiratory pressure and the maximal inspiratory pressure (MIP) measured at function residual capacity (FRC) level was emphasized. Both TTim and Wi/Wi(max) were measured in 35 normal subjects and 89 patients with chronic obstructive pulmonary disease (COPD). The results showed that normal value of TTim was 0.0253 +/- 0.0055 which corresponds to the normal value of the diaphragm tension-time index (TTdi = 0.02-0.03) reported by Bellemare. Patients with COPD had a mean TTim much higher than that of normals (P < 0.01). The works of inspiration (Wi) in patients with COPD increased, while the maximal works of inspiration (Wi(max)) declined, so Wi/Wi(max) became significantly greater than that of normals (P < 0.01). The results also showed that there was a linear relationship between Pi/Pimax and TTim or Wi/Wimax (r = 0.7891, 0.9738, 0.6459, 0.9327, P < 0.01). Therefore, we suggest that both TTim and Wi/Wimax can be used as clinical indices to reflect the reserve function of inspiratory muscles.

Adult↗
PubMed1984

Response to acute hypercapnia in the parents of victims of sudden infant death syndrome.

The ventilatory response to acute hypercapnia was studied in 68 parents of victims of sudden infant death syndrome and 56 control subjects. Tidal volume, inspiratory time, and total respiratory cycle time were measured before and immediately after a vital capacity breath of 13% CO2 in oxygen. Instantaneous minute ventilation, mean inspiratory flow (tidal volume/inspiratory time), and respiratory timing (inspiratory time/total respiratory cycle time) were calculated. Both groups of subjects showed a marked increase in tidal volume (48.4% +/- 26.5%), instantaneous minute ventilation (56% +/- 35%), and tidal volume/inspiratory time (56.8% +/- 33.5%) after inhalation of the test gas, with little change in inspiratory time/total respiratory cycle time. There were no significant differences between the two groups for ventilation before or after inhalation of the test gas. The ventilatory response to acute hypercapnia is mediated by the peripheral chemoreceptors. These results suggest that an inherited abnormality of peripheral chemoreceptor function is unlikely to be a factor leading to sudden infant death syndrome.

Acute Disease↗
PubMed1996

Transfer of carbon monoxide during an inspiratory pause procedure in mechanically ventilated pigs.

We studied the effect of forced inflation at different alveolar volumes (VA) on carbon monoxide diffusing capacity (DLCO) in anaesthetized, paralysed and mechanically ventilated healthy pigs. An inspiratory pause procedure (equivalent of the single-breath technique) consisting of a pause between an inflation and expiration, both at a constant flow rate, was used. The procedure was computer-controlled and could easily be standardized. In five pigs, VA was varied at constant inflation volume by increasing positive end-expiratory pressure (PEEP) from 2 to 10 cmH2O. Inspiratory pause time was varied from 1 to 8 s to verify whether the decay of CO was exponential. In nine pigs, DLCO was estimated at four different VA values by inflating with 15-30 ml kg-1 at 2 cmH2O PEEP. An exponential decay of CO was always obtained. With increasing VA by either an increase in PEEP or inflation volume, DLCO remained constant. Since the diffusing capacity of the pulmonary membrane is expected to increase with increasing VA, the constant DLCO may be attributed to a decrease in capillary blood volume.

Animals↗
PubMed2006

Effects of inspiratory muscle training on exercise responses in normoxia and hypoxia.

The purpose of this study was to determine the effects of inspiratory muscle training (IMT) on exercise in hypoxia (H) and normoxia (N). A 4-week IMT program was implemented with 12 healthy subjects using an inspiratory muscle trainer set at either 15% (C; n=5) or 50% (IMT; n=7) maximal inspiratory mouth pressure (PImax). Two treadmill tests (85% VO2max) to exhaustion and measures of diaphragm thickness (Tdi) and function were completed before and after training in H and N. Significant increases of 8-12% and 24.5+/-3.1% in Tdi and PImax, respectively, were seen in the IMT group. Time to exhaustion remained unchanged in all conditions. Inspiratory muscle fatigue (downward arrowPImax) following exercise was reduced approximately 10% (P<0.05) in IMT after both N and H. During H, IMT reduced (P<0.05) VO2 by 8-12%, cardiac output by 14+/-2%, ventilation by 25+/-3%; and increased arterial oxygen saturation by 4+/-1% and lung diffusing capacity by 22+/-3%. Ratings of perceived exertion and dyspnea were also significantly reduced. These data suggest that IMT significantly improves structural and functional physiologic measures in hypoxic exercise.

Adaptation, Physiological↗
PubMed1988

Targeted resistive ventilatory muscle training in chronic obstructive pulmonary disease.

To overcome the problem of altered breathing strategy during resistive ventilatory muscle training (VMT), we used a single-orifice inspiratory resistance together with a target feedback device (TFD) in patients with chronic obstructive pulmonary disease (COPD). In a preliminary study (study A), we showed that the resistance plus TFD was effective in controlling breathing strategy. We subsequently used the resistor plus TFD in a 5-wk study (study B) of VMT in 17 COPD patients who were randomized into high-intensity (HI) and low-intensity (LI) training groups. Compared with the LI group, the HI group showed significant increases in static maximal inspiratory pressure (21.3 vs. 5.0 cmH2O), maximal sustained ventilatory capacity (MSVC, 3.2 vs -0.1 l/min, sustained maximal mouth pressure (12.1 vs. 0.6 cmH2O), mean mouth pressure (6.9 vs. 3.9 cmH2O), peak inspiratory flow rate (12.3 vs. 4.0 l/min), and maximal sustained work rate (12.2 vs. 4.2 cmH2O.l-1.min-1). We conclude that targeted VMT with control of breathing strategy improves both ventilatory muscle strength and endurance.

Biofeedback, Psychology↗