Effects of externally imposed mechanical resistance on breathing dense gas at exercise: mechanics of breathing.
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Adult↗
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A computer-based data acquisition system for breathing and exercise entrainment studies.
An interactive, real-time, computer-based data acquisition system was designed to obtain data for breathing and exercise entrainment studies. By timing the steps of subjects walking on a treadmill relative to different points in the respiratory cycle (e.g. the beginning and end of inspiration), the relation between gait and ventilation can be followed on a breath-by-breath basis. Accurate establishment of the beginning and end of respiratory events from a pneumotachygraph signal was assured by using tidal volume thresholds for (1) noise, (2) minimum valid volume and (3) minimum duration.
Computers↗
Pulmonary artery pressure in thoracic scoliosis during and after exercise while breathing air and pure oxygen.
Pulmonary artery catheterisation was carried out in 25 scoliotics aged 13 to 67 years (mean 30.7). Each then performed a progressive exercise test breathing air, and 11 performed a similar test breathing pure oxygen. The mean pulmonary artery pressure (PAP) increased linearly with oxygen uptake (VO2) and with the work rate. The pressure responses have been described in terms of ther intercept and rate of rise of pressure (sPAP/VO2 and sPAP/work rate). sPAP/VO2 was unrelated to the anatomical features of the scoliosis, or to PaO2. It was inversely related to vital capacity, functional residual capacity, and total lung capacity. Inspiration of pure oxygen lowered the resting pressure by a mean of 3.2 mmHg but only decreased sPAP/work rate by 9%. The maximum pressure reached during exercise was diminished by a mean of 5.2 mmHg when pure oxygen was breathed. The mean pressures were shown to fall exponentially after exercise. The time constants were proportional to sPAP/VO2 and to the final pressure reached during exercise. Inspiration of pure oxygen did not effect the time constants but decreased the post-exercise pressure load by lowering the final pressure during exercise.
Adolescent↗
Effects of an external nasal dilator on the work of breathing during exercise.
PURPOSE: The effect of an external nasal dilator on the work of breathing (WOB) was measured during exercise in 14 untrained college students (age, 23 +/- 2.7 yr). METHODS: Two maximal, incremental ergometer tests were performed to exhaustion. Subjects wore a placebo or an active nasal dilator strip, in random order, during each test. An esophageal balloon was placed through each of the subject's mouth into the esophagus for measurement of inspiratory elastic work (INEW), inspiratory resistive work (INRW), and expiratory resistive work (EXRW). Subjects breathed through a Hans Rudolph(R) face mask that covered both the mouth and nose during both tests. Measured variables included oxygen uptake (VO2), ventilation (VE), tidal volume (VT), frequency of breathing (f), INEW, INRW, and EXRW (work expressed in joules). An alpha level was set at P < 0.05. RESULTS: No significant differences were found in INEW, INRW, and EXRW between conditions at 70% of VO2max (mean +/- SD; Placebo: INEW, 25.6 +/- 17.8 J.min-1; INRW, 22.4 +/- 15.8 J.min-1; EXRW, 16.7 +/- 12.3 J.min-1; Active: INEW, 24.7 +/- 12.9 J.min-1; INRW, 19.7 +/- 11.9 J.min-1; EXRW, 15.2 +/- 8.6 J.min-1; P > 0.05). No difference was found in INEW, INRW, and EXRW at maximal exercise between conditions (mean +/- SD; Placebo: INEW, 50.2 +/- 29.9 J.min-1; INRW, 67.3 +/- 42.3 J.min-1; EXRW, 102.3 +/- 78.4 J.min-1; Active: INEW, 45.7 +/- 19.6 J.min-1; INRW, 62.6 +/- 36.7 J.min-1; EXRW, 86.3 +/- 50.9 J.min-1; P > 0.05). There were no differences in VO2, VE, VT, or f between conditions. CONCLUSION: Wearing an external nasal dilator does not significantly reduce the work of breathing during exercise.
Adult↗
Delayed appearance of blood lactate with reduced frequency breathing during exercise.
The purpose of the present study was to investigate the blood lactate (LA-) responses to hypoventilation induced by reduced frequency breathing (RFB) during recovery from exercise. Five male subject performed 16 4 min cycling bouts alternating with 16 min rest periods. Exercise intensities were chosen at power outputs corresponding to 30% VO2max at 2 mMLA-, VO2 at 4 mMLA-, and 90% VO2max in each subject. Breathing frequency was voluntarily controlled starting 10 s before each 3rd min of exercise and maintained throughout the rest of the exercise period. Four different breathing patterns at each exercise intensity were used: normal breathing (NB), breathing every 4 s, breathing every 8 s, and maximal RFB. Except for the NB trials, subjects held their breath at functional residual capacity during each breathing interval. The concentration difference of LA- between the 3rd min sample and the 4th min sample was defined as the lactate change during exercise (delta LA-ex), and that between the 4th min sample and the sample at the 3rd min after the end of the exercise as the lactate change during recovery (delta LA-rec). An ANOVA showed significant (p less than 0.05) differences in breathing procedures only in delta LA-rec. delta LA-rec seemed to increase as compared to NB only at VO2 at 4 mMLA- and 90% VO2max, while delta LA-ex remained unchanged as compared to NB in spite of reduced VA. These results might indicate that RFB inhibited lactate removal from working muscles during exercise.
Adult↗
Exercise limitations in patients with pulmonary diseases.
An adequate analysis of the pathophysiology of the disease and of its ensuing type and degree of limitations is essential for evaluating the abilities for physical performance in patients with pulmonary diseases. Maximal exercise testing is an indispensable diagnostic tool in this respect. In light of moderate obstructive disease (FEV1 > approximately 60% pred), the exercise limitation comes from the cardio-circulatory system and/or peripheral muscle function. A rehabilitation program for these patients can be based on endurance training at high heart rate levels. Patients with a ventilatory limitation (FEV1 < 40%-60% pred.) show a failure of the respiratory pump, resulting in hypercapnia during exercise. Rehabilitation treatment will contain ergonomics, exercises for mobility and agility, breathing exercises with low-frequency breathing, relaxation exercises, and inspiratory muscle training. An oxygen-uptake limitation can be found in patients with a diffusion problem, severe ventilation-perfusion mismatch, or a reduced contact time between blood and alveolar gas. Such problems can often be seen in emphysema, and express themselves as isolated hypoxaemia during exercise. These patients benefit from a program consisting of ergonomics, exercises for mobilising the thoracic wall, low-frequency breathing, and exercising with additional oxygen. Many patients with chronic obstructive pulmonary disease (COPD) are limited for psychosocial reasons. The dyspnea is a negatively rewarding side effect of exercise in these patients. They tend to avoid all exertion, and thus get into a vicious circle of inactivity, low fitness, and unpleasant sensations during exercise. The inactivity often is also induced by the patient's family, since a 'patient-role' requires a quiet lifestyle.
Exercise Therapy↗
[The effects of deep breathing methods on pulmonary ventilatory function of pneumothorax patients undergoing a thoracotomy].
PURPOSE: This study was to examine the effects of deep breathing exercises with Incentive Spirometer on the pulmonary ventilatory function of pneumothorax patients undergoing a thoracotomy. METHOD: This experiment used anonequivalent control group non-synchronized design which compared pre-experimental measures with post-experimental ones. The subjects of this study were 34 inpatients who were scheduled for a thoracotomy and classified into the experimental group (17 patients) or control group (17 patients) by using an Incentive Spirometer or not. The collected data was analyzed by a SPSS Win/PC (percentage, mean, standard deviation, chi-square test, t-test, repeated measured two-way ANOVA). RESULT: The Pulmonary Ventilatory Function of the experimental and control group were significantly increased on the first day, third day, and fifth day after the thoracotomy, but the group interaction period was not significant. CONCLUSION: This study showed that the deep breathing exercises with an Incentive Spirometer and deep breathing exercise without an Incentive Spirometer were both effective for recovering the pulmonary ventilatory function after a thoracotomy.
Adult↗
Regulation of breathing during exercise in normal subjects and in chronic lung disease.
1. The breathing pattern in normal subjects during exercise was compared with that in patients with obstructive and restrictive lung defects. 2. In most normal women and patients with obstructive or restrictive lung disease, as the frequency of breathing increased both inspiratory and expiratory duration fell. However, in most normal men (74 per cent) inspiratory duration did not fall as ventilation increased. 3. Women breathed faster than men, and both obstructed and restricted patients breathed faster than normal subjects. 4. The airflow patterns in normal men and women were similar, but most patients with restrictive or obstructive lung disease showed an approximately exponential fall in flow during expiration.
Adult↗
Breathing He-O2 increases ventilation but does not decrease the work of breathing during exercise.
We previously observed an increase in minute ventilation (V E) with resistive unloading (He-O2 breathing) in healthy elderly subjects with normal pulmonary function. To investigate the effects of resistive unloading in elderly subjects with mild chronic airflow limitation (FEV(1)/FVC: 61 +/- 4%), we studied 10 elderly men and women 70 +/- 3 yr of age. These subjects performed graded cycle ergometry to exhaustion, once breathing room air and once breathing a He-O2 gas mixture (79% He, 21% O2). V E, pulmonary mechanics, and PET(CO2) were measured during each 1-min increment in work rate. Data were analyzed by paired t test at rest, at ventilatory threshold (VTh), and during maximal exercise. V E was significantly (p < 0.05) increased at VTh (3.4 +/- 4.0 L/min or 12 +/- 15% increase) and maximal exercise (15.2 +/- 9.7 L/min or 22 +/- 13% increase) while breathing He-O2. Concomitant to the increase in V E, PET(CO2) was decreased at all levels (p < 0.01), whereas total work of breathing against the lung was not different. We concluded that V E is increased during He-O2 breathing because of resistive unloading of the airways and the maintenance of the relationship between the work of breathing and exercise work rate.
Age Factors↗
Longitudinal study (32 years) of exercise tolerance, breathing response, blood pressure, and blood lipids in young men.
Changes in exercise tolerance, blood lipids, and blood pressure from youth to middle age was studied in 106 subjects followed 32 years. In addition, the responses to cold pressor and CO2 stress were studied as correlates of future lipids and blood pressure. Treadmill exercise test, cold pressor test, response to breathing a mixture of 6% CO2, and 21% O2, for 5 minutes, blood pressure, and lipid measurements were performed in 1947 when subjects were 20 +/- 2 years old. Exercise, blood pressure and lipid tests were repeated in 1979. Tracking of blood pressure and pulse response to exercise over the period was demonstrated. Baseline exercise response correlated with future blood pressure, cholesterol, triglycerides, and high density lipoproteins. Change in exercise pulse rate over the period correlated with change in cholesterol. Cold pressor systolic blood pressure response correlated with future systolic blood pressure and triglycerides. Pulse and blood pressure response to CO2 breathing correlated with cholesterol, triglyceride and high density lipoprotein 32 years later. These correlations were independent of baseline values of the variables and body mass index. Individuals who were judged "fit" (exercise pulse rise less than median) at both baseline and follow-up had the best cardiovascular risk profile (blood pressure and lipids). Blood pressure and pulse response to exercise tracked between ages 20 and 50. Exercise, cold pressor, and CO2 responses in youth correlated with blood lipid levels in middle age.
Adolescent↗
Effectiveness of a breath during exercise in a hyperbaric environment.
During vigorous foot-pedal exercise at 6.75 ATA, three subjects had lower total ventilation, larger functional residual capacity (FRC), and higher PCO2 in end-expired and mixed-expired gas than during the same exercise at 1.5 ATA. Compartmental analysis of multiple breath washin suggested that ventilation was more evenly distributed during the high pressure exercise. Mass-balance analysis of inert indicator gases in single breaths showed that at a given pressure, low-diffusivity gases did not mix in the lung as well as high-diffusivity gases. It did not follow, however, that a particular gas was better mixed at low pressure than when its diffusivity was decreased by high pressure; the data showed just the opposite during exercise. The apparent paradox seems to be explained by the change of other conditions for mixing at high pressure, especially the enlargement of the FRC.
Atmospheric Pressure↗
The effect of positive expiratory pressure versus forced expiration technique on tracheobronchial clearance in chronic bronchitics.
In a randomized cross-over trial, including a control measurement the effect of positive expiratory pressure (PEP) and forced expiration technique (FET) on tracheobronchial clearance was evaluated in eight chronic bronchitics with abundant sputum production (mean, 32 g/day). PEP consisted of PEP-mask breathing interspersed with breathing exercises, huffing, and coughing. FET consisted of postural drainage, breathing exercises, huffing, and coughing. Clearance was measured with a radio-aerosol technique. At 40 min after the start of therapy the mean clearance, expressed as percentage of the amount of radioactivity present at the start of therapy, was 32% after PEP, 53% after FET, and 15% in the control run. The difference between PEP, FET, and control was statistically significant (p less than 0.02). Sputum production during PEP and FET was larger than during the equivalent period of time in the control run. It is concluded that FET is more effective than PEP in enhancing tracheobronchial clearance.
Breathing Exercises↗
Nasal contribution to breathing with exercise: effect of race and gender.
Because the nose acts as a filter to prevent penetration of toxic particles and gases to the lower respiratory tract, the route of breathing, oral vs. nasal, may be an important determinant of toxicant dose to the lungs. Using respiratory inductance plethysmography and a nasal mask fitted with flowmeter, we measured the nasal contribution to breathing at rest and during exercise (to 60% maximum workload) in healthy young adults (men/women = 11/11 and Caucasian/African-American = 11/11). We found that the nasal contribution to breathing is less during submaximal exercise in the Caucasians vs. African-Americans (e.g., at 60% maximum workload, mean nasal-to-total ventilation ratio = 0.40 +/- 0.21 and 0.65 +/- 0.24, respectively, P < 0.05). This difference is likely due to the African-Americans' ability to achieve higher maximal inspiratory flows through their nose than the Caucasians. Men also had a lesser nasal contribution to breathing during exercise compared with women. This is likely due to greater minute ventilations at any given percentage of maximum workload in men vs. women.
Adult↗
Exercise-entrained breathing and non-invasive determination of anaerobic threshold.
Incremental cycle exercise was performed by 17 subjects under two breathing conditions: spontaneous breathing (Non-ENT run) and deliberate entrainment of breathing frequency (f) to cycling rate at preferred coupling ratios up to possibly high work rates (ENT run). The purpose was to investigate the influence of entrainment on two non-invasive determinations of anaerobic threshold (AT): the break points of VE/VO2 (VAT) and VCO2 (V-slope AT) changes against VO2. Compared to the Non-ENT run, VAT in the ENT run was greater in 12 subjects entrained at higher f accompanied by relative hyperventilation at low work rates, while it was similar in five subjects entrained at lower f accompanied by relative hypoventilation. Relative hyperventilation and hypoventilation during the ENT run tended to elicit greater and lower VCO2, respectively, relative to VO2, as compared to the Non-ENT run. These different VCO2, responses between the two runs exerted little influence on the V-slope AT determination. It is concluded that breathing patterns and ventilatory response during incremental work tests can affect the VAT method but not the V-slope method.
Adult↗
Short duration exercise increases breath hydrogen excretion after lactulose ingestion: description of a new phenomenon.
OBJECTIVE: There is limited information on the effect of exercise on colonic function. Beneficial effects have been described, including prevention of colon cancer. In the present study, we demonstrate that short duration exercise results in enhancement of breath hydrogen excretion after consumption of lactulose. METHODS: Twelve normal volunteers who performed regular exercise were recruited. Each study subject underwent four study sessions (two resting and two exercise) after consumption of 10 g of crystalline lactulose. Colonic hydrogen production was measured in mid-expiratory breath samples obtained at baseline and frequent intervals to 420 min. Exercise sessions consisted of 5 min on a treadmill at a 20% incline at 10 km/h. This was performed 180 min after lactulose ingestion in the two exercise sessions. RESULTS: A characteristic pattern in the hydrogen concentration versus time curves was seen after exercises, consisting of an initial decrease then an increase in concentration above baseline for up to 3 h. Mean area under the curve from 0 to 420 min for resting studies was 5,156 +/- 2,621 ppm/min and was 7,051 +/- 2,447 ppm/min for exercise studies, p < 0.05 (37% increase). Mean area under the curve from 180 to 420 min was 2,808 +/- 1,592 ppm/min for resting studies and 4,543 +/- 1,729 for exercise studies, p < 0.005 (62% increase). CONCLUSION: This study demonstrates that exercise potentially enhances the metabolism of lactulose by colonic bacteria. The authors postulate that this effect is due to stirring of the colonic contents. The described phenomenon may explain, in part, the beneficial effects of exercise on colonic mucosa.
Adult↗
Prevention of respiratory complications after abdominal surgery: a randomised clinical trial.
OBJECTIVE: To evaluate the prevention of respiratory complications after abdominal surgery by a comparison of a global policy of incentive spirometry with a regimen consisting of deep breathing exercises for low risk patients and incentive spirometry plus physiotherapy for high risk patients. DESIGN: Stratified randomised trial. SETTING: General surgical service of an urban teaching hospital. PATIENTS: 456 patients undergoing abdominal surgery. Patients less than 60 years of age with an American Society of Anesthesia classification of 1 were considered to be at low risk. OUTCOME MEASURES: Respiratory complications were defined as clinical features consistent with collapse or consolidation, a temperature above 38 degrees C, plus either confirmatory chest radiology or positive results on sputum microbiology. We also recorded the time that staff devoted to prophylactic respiratory therapy. RESULTS: There was good baseline equivalence between the groups. The incidence of respiratory complications was 15% (35/231) for patients in the incentive spirometry group and 12% (28/225) for patients in the mixed therapy group (P = 0.40; 95% confidence interval -3.6% to 9.0%). It required similar amounts of staff time to provide incentive spirometry and deep breathing exercises for low risk patients. The inclusion of physiotherapy for high risk patients, however, resulted in the utilisation of an extra 30 minutes of staff time per patient. CONCLUSIONS: When the use of resources is taken into account, the most efficient regimen of prophylaxis against respiratory complications after abdominal surgery is deep breathing exercises for low risk patients and incentive spirometry for high risk patients.
Abdomen↗
Influence of global inspiratory muscle fatigue on breathing during exercise.
We evaluated the effect of global inspiratory muscle fatigue (GF) on respiratory muscle control during exercise at 30, 60, and 90% of maximal power output in normal subjects. Fatigue was induced by breathing against a high inspiratory resistance until exhaustion. Esophageal and gastric pressures, anteroposterior displacement of the rib cage and abdomen, breathing pattern, and perceived breathlessness were measured. Induction of GF had no effect on the ventilatory parameters during mild and moderate exercise. It altered, however, ventilatory response to heavy exercise by increasing breathing frequency and minute ventilation, with minor changes in tidal volume. This was accompanied by an increase in perceived breathlessness. GF significantly increased both the tonic and phasic activities of abdominal muscles that allowed 1) the diaphragm to maintain its function while developing less pressure, 2) the same tidal volume with lesser shortening of the rib cage inspiratory muscles, and 3) relaxation of the abdominal muscles to contribute to lung inflation. The increased work performed by the abdominal muscles may, however, lead to a reduction in their strength. GF may impair exercise performance in some healthy subjects that is probably not related to excessive breathlessness or other ventilatory factors. We conclude that the respiratory system is remarkably adaptable in maintaining ventilation during exercise even with impaired inspiratory muscle contractility.
Adult↗
Quantitative analysis of trace gases of breath during exercise using the new SIFT-MS technique.
We show how the concentration of the breath gases ammonia, acetone, and isoprene vary with time during exercise using the new selected ion flow tube mass spectrometry (SIFT-MS) technique. The expired breath concentrations of ammonia, acetone and isoprene were observed within the range of 50-500, 100-1400 and 5-400 ppb, respectively. Increasing acetone levels were observed for most subjects during the exercise period. However, isoprene levels decreased with time during exercise. Older subjects showed higher levels of isoprene compared with younger subjects. The ammonia time profile with exercise showed both decreasing and increasing patterns for different subjects.
Acetone↗