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PubMed1995

Cutaneous vasoconstrictor response induced by inspiratory gasp in relation to sex and age.

1. Vasoconstrictor responses to inspiratory gasp were determined in fingertip skin by laser Doppler flowmetry in relation to age and gender of healthy adults. Variations of the responses were examined together with variations in body mass index and vital capacity. 2. In the absence of any significant difference in the baseline blood flow, the index of vasoconstrictor response (per cent change) induced by inspiratory gasp was higher in young males than in young females (71.4% versus 59.4%; P < 0.05), and in the same direction as the change in vital capacity determined in the same laboratory setting. Similar parallel differences in the indexes of vasoconstrictor response and vital capacity existed between young and middle-aged males, suggesting that the differences observed were not due to gender or age per se. 3. Strong positive correlations between the index of the vasoconstrictor response and vital capacity in the same subject were found when young males and females were pooled together and when young and middle-aged males were pooled together. Furthermore, after graded inspiratory gasp, graded vasoconstrictor response was observed in the same subject, indicating a close relationship between the depth of inspiration (magnitude of stimulus) and the index of the vasoconstrictor response (reactivity). 4. We concluded that the index of the vasoconstrictor response induced by inspiratory gasp depends significantly on the magnitude of the vital capacity. These results provide a new approach for quantifying dynamic changes in skin blood flow and raise caveats about comparing differences in neurovascular functions using single measurements of vasoconstrictor response induced by inspiratory gasp as an index.

Adult↗
PubMed2001

Supine fall in lung volumes in the assessment of diaphragmatic weakness in neuromuscular disorders.

OBJECTIVE: To determine whether diaphragmatic function can be determined by noninvasive respiratory indices in neuromuscular disease. DESIGN: Vital capacity (VC) and mouth pressure generated during a maximal static inspiratory effort (Pi max) were measured with patients in both sitting and supine positions. SETTING: Rehabilitation hospital. PATIENTS: Twenty-four patients with generalized neuromuscular disease. MAIN OUTCOME MEASURES: Changes in indices from sitting to supine position were compared with invasive diaphragmatic function indices consisting of transdiaphragmatic pressures during maximal sniff (Pdi sniff) and the ratio of gastric pressure (Pga) increases over transdiaphragmatic pressure (DeltaPga/DeltaPdi) during quiet breathing. RESULTS: The fall in VC in the supine position was greater in the 15 patients who had spontaneous paradoxical diaphragmatic motion (DeltaPga/DeltaPdi < 0) than in the 9 patients who did not. Specificity and sensitivity of a greater than 25% supine fall in VC for the diagnosis of diaphragmatic weakness (DeltaPga/DeltaPdi < 0 and/or Pdi sniff < 30cmH2O) were 90% and 79%, respectively. Stepwise multiple regression analysis of Pdi sniff showed that both the supine fall in VC and Pi max were associated with diaphragmatic weakness (R(2) =.66; p <.0001). These factors contributed 52% and 14% of the Pdi sniff variance, respectively. CONCLUSIONS: Simple VC measurement in the sitting and supine positions may be helpful in detecting severe or predominant diaphragmatic weakness.

Adult↗
PubMed1983

Role of labour in the establishment of functional residual capacity at birth.

Intrathoracic pressure and volume changes were measured during the spontaneous first breath in 11 healthy term neonates delivered by emergency caesarean section (CS). Although inspiratory and expiratory rates were higher than those found among babies delivered by elective CS, inspiratory volume was very similar and these babies, unlike those delivered by elective CS, had all formed a functional residual capacity at the end of the first breath. We obtained cord arterial and venous samples for catecholamine analysis concurrently, and found that most of the babies had concentrations of plasma noradrenaline similar to babies delivered by elective CS--high values were found only among infants who had suffered fetal distress. Both catecholamine excretion and method of delivery may be important in the formation of the functional residual capacity at birth.

Cesarean Section↗
PubMed2001

Tracheal intubation without muscle relaxant--a technique using sevoflurane vital capacity induction and alfentanil.

This randomized controlled study examined intubating conditions and haemodynamic changes following sevoflurane nitrous oxide induction in four groups: three different doses of alfentanil compared with low-dose alfentanil and suxamethonium. All patients received atropine 0.3 mg i.v. before induction of anaesthesia with vital capacity breaths of sevoflurane 8% (more than 7% in the inspiratory gas) in 60% nitrous oxide and oxygen. Patients were allocated randomly to four groups of intravenous supplements: group SA20, alfentanil 20 microg x kg(-1); group SA25, alfentanil 25 microg x kg(-1); group SA30, alfentanil 30 microg x kg(-1); group SSA, alfentanil 10 microg x kg(-1) and suxamethonium 1 mg x kg(-1). Orotracheal intubation and assessment of intubating conditions was performed by one of the investigators who was blinded to the subject's group. Intubating conditions were satisfactory or excellent in 83%, 80%, 92% and 96% of patients in groups SA20, SA25, SA30 and SSA respectively. These differences were not statistically significant. The increase in heart rate associated with laryngoscopy and tracheal intubation was effectively attenuated in all groups. Mean arterial pressure decreased significantly and similarly after induction in all groups. Two minutes after intubation the mean arterial pressure was increased significantly (P<0.05) compared to the post-induction value in group SSA. The intubating conditions obtained with sevoflurane plus alfentanil 30 microg x kg(-1) were comparable to those provided by the sevoflurane, suxamethonium and alfentanil 10 microg x kg(-1) combination.

Adolescent↗
PubMed1996

Effect of lung volume on the respiratory action of the canine sternomastoid.

We tested the hypothesis that because the resting length of the canine sternomastoid (SM) muscles is relatively insensitive to lung volume change, the SM may maintain its inspiratory force generation regardless of lung volume. The relationships between SM pre- and postcontraction in situ fiber lengths and SM-produced inspiratory pressure generation [i.e., esophageal (Pes)] and rib cage displacements were examined in adult supine anesthetized dogs at residual volume (RV), functional residual capacity, and total lung capacity. SM muscle contraction was produced by isolated bilateral supramaximal electrical stimulation during hyperventilation-induced apnea. In all animals, SM contraction produced negative change in Pes (i.e., an inspiratory action). Passively increasing lung volume from RV to total lung capacity decreased (P < or = 0.01) the SM-produced Pes by -66 +/- 4% but had a relatively small effect on SM in situ pre- and postcontraction fiber length (< 3%). Whereas SM contraction at RV produced a cranial displacement of the sternum and increased the upper rib cage cross-sectional area, passively elevating lung volume diminished the SM-produced expansion of the upper rib cage. Hyperinflation did not increase the impedance of the sternum to cranial displacement during SM contraction, suggesting that hyperinflation caused a dissociation between the mechanical action of the sternum and the upper rib cage. These results suggest that mechanical dissociation of the ribs and sternum may diminish the contribution of the SM to inspiratory volume generation when breathing is done from elevated end-expiratory lung volumes.

Animals↗
PubMed2006

Pulmonary function in renal transplant recipients and end-stage renal disease patients undergoing maintenance dialysis.

The aim of this study was to reveal the pulmonary function status of renal transplant recipients and chronic renal failure patients on hemodialysis or continuous ambulatory peritoneal dialysis. The study involved 73 subjects, including 49 patients who were either on peritoneal dialysis (n = 22) or hemodialysis (n = 27), and 24 renal transplant recipients. The spirometry results revealed significantly higher residual volume and total lung capacity in the hemodialysis and peritoneal dialysis groups than in the transplantation group. Forced expiratory flow between 25% and 75% of vital capacity was slightly below normal in the dialysis patients. Preservation of diffusion capacity of the lung for carbon monoxide was noted in the hemodialysis group (112.4%). Inspiratory and expiratory muscle strength was reduced in all groups. Only type of dialysis was correlated with this reduction. Inspiratory muscle strength in the peritoneal dialysis group (49.9%) was significantly lower than in the transplantation and hemodialysis groups (54.7% and 66.5%, respectively). The spirometry findings suggest that small-airway disease causes increased residual volume and total lung capacity (hyperinflation) in hemodialysis and peritoneal dialysis patients and that this airway obstruction subsides after renal transplantation. Preserved diffusion capacity in the hemodialysis group was attributed to the use of biocompatible dialyzer membranes. Renal failure complications may be the main explanation for global respiratory muscle weakness in dialysis patients, whereas corticosteroid therapy might be the primary cause in kidney graft recipients. Significantly lower inspiratory muscle strength in the peritoneal dialysis group suggests that presence of intra-abdominal dialysate might interfere with diaphragmatic contraction.

Adrenal Cortex Hormones↗
PubMed2001

Pulmonary dysfunction in adults with nephropathic cystinosis.

OBJECTIVE: To characterize the pulmonary dysfunction in patients with nephropathic cystinosis after renal transplantation. DESIGN: Cross-sectional analysis of consecutive adult patients. PATIENTS: Twelve adult, nephropathic cystinosis patients and 3 adult, ocular, nonnephropathic cystinosis patients admitted to the National Institutes of Health Clinical Center. RESULTS: The 12 nephropathic cystinosis patients (age range, 21 to 40 years) showed an extraparenchymal pattern of restrictive lung disease, with inspiratory and expiratory dysfunction. Specifically, the mean FVC was 58% of predicted, the mean FEV(1) was 57% of predicted, and the mean total lung capacity was 66% of predicted, while the mean residual volume was normal. Furthermore, the mean maximal inspiratory pressure for the eight patients tested was 40% of predicted, and the mean maximal expiratory pressure was 26% of predicted. Two patients died of respiratory insufficiency. All the patients had lived at least 17 years, while lacking compliant cystine-depleting therapy with oral cysteamine. Seven patients had a conical chest, restricting excursion, and 10 of the 12 patients had evidence of the myopathy that typifies late cystinosis. In fact, the severity of pulmonary disease correlated directly with the severity of myopathy in our group of 12 patients. In contrast, the lung parenchyma was essentially normal, as gauged by chest radiographs and CT scans of the lung. The three patients with nonnephropathic cystinosis displayed entirely normal pulmonary function. CONCLUSION: The distal myopathy characteristic of nephropathic cystinosis results in an extraparenchymal pattern of restrictive lung disease in adults who have not received long-term cystine depletion. Whether or not oral cysteamine therapy can prevent this complication remains to be determined.

Adult↗
PubMed1986

Pulmonary ventilation, CO2 response and inspiratory drive in spontaneously breathing young infants during halothane anaesthesia.

Pulmonary ventilation, CO2 response and inspiratory drive were studied during halothane anaesthesia prior to surgery in 13 spontaneously breathing infants less than 6 months of age. Pneumotachography and capnography were used. Airway and oesophageal pressures were measured and occlusion tests were performed at functional residual capacity. Measurements were made before and during 8 min of 4% CO2 stimulation. Inspiratory drive increased significantly (P less than 0.001) at CO2 stimulation. This resulted in increased minute ventilation (P less than 0.001) and tidal volume (P less than 0.001) while respiratory rate was unchanged. As VBohrD/VT ratios were the same, the net effect was increased alveolar ventilation (P less than 0.001). CO2 elimination was unpredictable in these young infants and decreased during CO2 stimulation (P less than 0.05), while mean end-tidal CO2 concentration only increased from 5.2 to 6.3% (P less than 0.001). The ventilatory response to 4% CO2 could therefore be deemed to be adequate during the short period (8 min) of CO2 breathing. However, this was achieved at the cost of increased work as witnessed by the increased ratio between minute ventilation and CO2 elimination (P less than 0.01). Stabilisation of end-tidal CO2 concentrations during CO2 inhalation took only 10 s while the maximal increase in ventilation volumes was not achieved until after 150 s. It is concluded that young spontaneously breathing infants anaesthetized with halothane (MAC 1.3) have an increased respiratory drive with greater tidal volumes during CO2 stimulations. Respiratory timing, dynamic compliance and total pulmonary resistance were, however, uninfluenced by 4% CO2 stimulation. Increased monitoring of CO2 output in anaesthetized infants is suggested.

Anesthesia, General↗
PubMed1997

Sniff nasal inspiratory pressure in patients with chronic obstructive pulmonary disease.

In subjects with normal lung mechanics, inspiratory muscle strength can be reliably and easily assessed by the sniff nasal inspiratory pressure (SNIP), which is the pressure measured in an occluded nostril during a maximal sniff performed through the contralateral nostril. The aim of this study was to assess the validity of the SNIP in patients with chronic obstructive pulmonary disease (COPD), where pressure transmission from alveoli to upper airways is likely to be dampened. Twenty eight patients with COPD were studied (mean forced expiratory volume in one second (FEV1) = 36% of predicted). The SNIP and the sniff oesophageal pressure (sniff Poes) were measured simultaneously during maximal sniffs, and were compared to the maximal inspiratory pressure obtained against an occlusion (MIP). All measurements were performed from functional residual capacity in the sitting position. The ratio SNIP/sniff Poes was 0.80, and did not correlate with the degree of airflow limitation. The ratio MIP/sniff Poes was 0.87, and the ratio SNIP/MIP was 0.97. Inspiratory muscle weakness, as defined by a low sniff Poes, was present in 17 of the 28 patients. A false diagnosis of weakness was made in eight patients when MIP was considered alone, in four when SNIP was considered alone, and in only three patients when MIP and SNIP were combined. We conclude that both the sniff nasal inspiratory pressure and the maximal inspiratory pressure moderately underestimate sniff oesophageal pressure in chronic obstructive pulmonary disease. Although suboptimal in this condition, the sniff nasal inspiratory pressure appears useful to complement the maximal inspiratory pressure for assessing inspiratory muscle strength in patients with chronic obstructive pulmonary disease.

Adult↗
PubMed1997

Ventilatory capacities at sea level and high altitude.

Because air is less dense at high altitude (HA), airway resistance is reduced and maximum inspiratory and expiratory flows are greater than at sea level (SL). Despite the reduction in airway resistance, ventilatory muscle endurance may be decreased by hypobaric hypoxia and, thus, may be a factor in limiting exercise at HA. To explore the effects of HA on ventilatory capacities and their relation to ventilatory demands of exercise, we measured 15-s maximum voluntary ventilation (MVV), 15-min maximum sustainable ventilation (MSV), and maximum airway pressures (Plmax and PEmax) in 18 healthy young men at SL and HA (Pikes Peak, 4300 m, or hypobaric chamber, PB approximately 460 mmHg). In eight of these subjects ventilatory capacities were compared with exercise ventilations. We also measured the effects of 36% O2 on the MSV in 12 of the subjects exposed to simulated altitude. Similar results were obtained at either simulated or actual HA. We found that MVV increased (p < 0.001) by 20% and the MSV (p < 0.001) by 15% at HA. Administration of 36% O2 at HA increased MSV further by 5% with no effect on MVV. No effect of HA on maximum inspiratory and expiratory pressures was found. We confirmed previous findings of modest increases in forced 1-s expired volume (FEV1) and slight decreases in forced vital capacity (FVC) at HA. At both SL and HA, the MSV exceeded the ventilatory demands of submaximal cycle exercise that could be sustained for about 30 min. During progressive cycle exercise to exhaustion, however, peak VE was not different from MVV, either at SL or HA. We conclude that the small, but significant, increase in MSV with 36% O2 administration at HA suggests that hypoxia decreases ventilatory endurance for flow loads as determined by the MSV. Thus, the possibility that ventilatory limits have a role in cessation of exercise at high altitude cannot be ruled out.

Adult↗
PubMed1989

Contribution of central and reflex nervous activity to the rapid increase in pulmonary ventilation at the start of muscular exercise in man.

To investigate the relative contributions of the central and peripheral neural drive to hyperventilation at the onset of muscular exercise, five volunteers were tested during the first ten breaths while performing both voluntary (VM) and passive (PM) ankle rotations with a frequency of 1 Hz and through an angle of 10 degrees. Resulting breathing patterns for the two movements were compared. Hypocapnic hyperventilation, found in both PM and VM, indicated its neural origin. Respiratory changes were higher in VM than in PM. In both experimental conditions, increases in ventilation (VE) depended more on respiratory frequency (f) than on tidal volume (VT). Moreover, increases in VT adapted, breath-by-breath, to values lower than the initial ones, while increases in f rose progressively. Expiratory time was reduced more than inspiratory time (TI); increases in inspiratory flow (VT/TI) depended to the same extent on changes in both TI and VT. Increases in expiratory tidal volume were initially higher than in inspiratory tidal volume, thereby producing a reduction in functional residual capacity. Because PM respiratory changes could be considered to be of nervous reflex origin only, the identical breathing patterns in PM and VM indicated that the hyperventilation found also in VM was mainly of reflex origin. The increase in VE was considered to be dependent on a greater stimulus from muscle proprioreceptors.

Adult↗
PubMed1987

Monitoring of neuromuscular function.

Monitoring neuromuscular transmission provides valuable information to the anesthesiologist. The acquisition of relevant data contributes to a more predictable and rational approach to the use of muscle relaxants and assures improved patient care during and in the immediate postoperative period. Clinical noninvasive criteria such as the presence or absence of diplopia and or ptosis, the ability to open the eyes widely, protrude the tongue or swallow, measurement of hand grip strength or head lift or assessment of the vital capacity are limited to awake and cooperative patients. Measurement of inspiratory force and tidal volume can be evaluated in anesthetized patients breathing spontaneously. Central depressant drugs tend to depress these respiratory parameters. Accordingly, the assumption that relaxants are responsible for respiratory depression at the end of an anesthetic can only be documented when impairment of neuromuscular transmission can be demonstrated. The most reliable method of measuring neuromuscular function is to stimulate an accessible peripheral motor nerve and measurement of the evoked response of the skeletal muscle or muscles innervated by the stimulated motor nerve. The evoked muscle response depends on the pattern of motor nerve stimulation: Single twitch stimuli at a defined frequency, tetanic stimulation, posttetanic single twitch stimulation or train-of-four stimulation. The response to these different modes of stimulation can be assessed either mechanically (evoked tension response) or electrically (evoked electromyography: EMG or integrated EMG). These response criteria can be employed either individually or combined to evaluate the response to muscle relaxants and to assess the adequacy of recovery from neuromuscular blockade.

Electric Stimulation↗
PubMed1991

Respiratory muscle recruitment in awake ponies during exercise and CO2 inhalation.

We measured respiratory muscle electromyograms (EMG), inspiratory (I) and expiratory (E) airflow patterns and functional residual capacity (FRC) in six ponies at rest, during treadmill walking at 1.8 mph-5, 10, and 15% grades, and during 2, 4, and 6% CO2 inhalation. There were several similarities in the responses to exercise and CO2 inhalation. The shapes of the I and E flow patterns were not changed appreciably from the respective control patterns during either condition. Mean diaphragm EMG increased from control (P less than 0.05) at 1.8 mph-10 and 15% grades, and during 4 and 6% inhalation. However, mean transversus abdominis EMG did not change significantly from control (P greater than 0.10) during either condition. Exercise did not have an effect (P greater than 0.05) on FRC, and there was only a slight (P less than 0.05) increase in FRC (100 ml or 2%) during 6% CO2 inhalation. Based on the fact that we did not find major differences between exercise and CO2 inhalation in mean diaphragm and transversus abdominis EMG, I and E flow patterns, and FRC we conclude that factor(s) other than the ventilatory stimulus and the non-ventilatory functions of the respiratory muscles are important determinants of the pony's respiratory muscle recruitment pattern under these conditions.

Animals↗
PubMed1992

The external respiration and gas exchange in space missions.

Literature data and results of our own studies into an effect of micro- and macro-gravity on an external respiration function of man are presented. It is found that in cosmonauts following the 7-366 day space missions there is an enhanced tendency associated with an increased flight duration toward a decrease in the lung volume and breathing mechanics parameters: forced vital capacity of the lungs FVC) by 5-25 percent, peak inspiratory and expiratory (air) flows (PIF, PEF) by 5-40 percent. A decrease in FVC appears to be explained by a new balance of elastic forces of the lungs, chest and abdomen occurring in microgravity as well as by an increased blood filling and pulmonary hydration. A decline of PIF and PEF is probably resulted from antigravitational deconditioning of the respiratory muscles with which a postflight decreased physical performance can in part be associated. The ventilation/perfusion ratios during orthostasis and +Gz and +Gx accelerations are estimated. The biophysical nature of developing the absorption atelectases on a combined exposure to accelerations and 100% oxygen breathing is confirmed. A hypothesis that hypervolemia and pulmonary congestion can increase the tendency toward the development of atelectases in space in particular during pure oxygen breathing is suggested. Respiratory physiology problem area which is of interest for space medicine is defined.

Aerospace Medicine↗
PubMed2005

Dyspnea during daily activities in chronic spinal cord injury.

OBJECTIVE: To assess factors associated with breathlessness in chronic spinal cord injury (SCI) during daily activities. DESIGN: Cross-sectional survey. SETTINGS: Veterans Affairs SCI service and the community. PARTICIPANTS: Four hundred forty-one participants 1 or more years post-SCI, and without acute illness, were recruited between 1994 and 2003 and were categorized according to their ability to walk unassisted, walk with an aid, or to move about by either hand-propelled wheelchair or motorized wheelchair (MWC). INTERVENTIONS: Assessment of injury extent, respiratory symptoms, cigarette smoking, comorbid medical conditions, and spirometry. MAIN OUTCOME MEASURES: Breathlessness during talking, eating, or dressing. RESULTS: Breathlessness was more common in MWC users (20/85 users, 24%) than in nonusers (20/356, 6%). The main activity associated with breathlessness in 15 MWC users was talking (18%). In MWC users, the risk of breathlessness was related to lifetime cigarette smoking (odds ratio [OR]=1.02; 95% confidence interval [CI], 1.00-1.03 per pack year), and reports of chronic cough (OR=7.8; 95% CI, 2.0-32.7), and wheeze (OR=3.5; 95% CI, 1.04-13.6). SCI level, percentage of predicted forced vital capacity and forced expiratory volume in 1 second, and maximal inspiratory pressures were not related to breathlessness. CONCLUSIONS: Breathlessness during selected daily activities (most commonly talking) was greatest in SCI participants who were most impaired with regard to mobility and was associated with reports of coughing, wheezing, and cigarette smoking.

Activities of Daily Living↗
PubMed2002

[Respiratory changes during ascension to 8,000 meters mountain].

BACKGROUND: Our goal was to determine whether spirometric alterations occur during expeditions to 8,000-metre peaks, and whether these are modified by acclimatization or are related to acute mountain sickness, to arterial oxygen saturation (SaO2) or to muscular deterioration due to chronic hypoxic exposure. SUBJECTS AND METHOD: Forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), inspiratory (MIP) and expiratory (MEP) maximal static pressures, grip strength in both hands, and SaO2 at rest and exercise were measured in eight subjects during an expedition to Gasherbrum II (8,035 m). RESULTS: Upon arrival at the base camp (5,200 m), both FVC and FEV1 decreased, with no changes in the FEV1/FVC ratio. FVC did not improve after a brief pressurisation in a portable hyperbaric chamber. A month later, FVC in the base camp returned to normal values. FVC fall correlated with both the severity of acute mountain sickness and weight loss. Resting SaO2 improved with acclimatisation and correlated with the previous hypoxic ventilatory response, both before and after acclimatisation. Acclimatisation led to a decrease in the exercise-induced SaO2 fall. Stay at a high altitude lowered body weight and grip strength, although MIP and MEP remained unchanged. CONCLUSIONS: We observed a restrictive alteration was corrected by with acclimatisation. This phenomenon seems to be related to a subclinical high-altitude pulmonary oedema rather than to an increase in the pulmonary vascular volume. Despite the high-altitude muscular deterioration, respiratory muscle weakness was not

Adult↗
PubMed1983

Depression of respiratory function by pneumatic antishock trousers in traumatic quadriplegia.

A case of mild hypoventilation associated with an incompletely inflated pneumatic antishock suit in traumatic quadriplegia is presented. Pulmonary function studies were performed on the same patient 23 days later. Base line studies were performed and then repeated with the antishock suit inflated to 40 and then 100 mm Hg. Measurements were made of tidal volume (Vt), inspiratory reserve volume (IRV), expiratory reserve volume (ERV), forced vital capacity (FVC), forced vital capacity in one second (FEV1), and maximum voluntary ventilation (MVV). With increasing suit pressures, all parameters decreased with the exception of the ERV, which was initially zero. Traumatic quadriplegia must be added to the list of disorders in which caution must be used when considering the use of the abdominal compartment of the pneumatic antishock suit.

Accidents, Traffic↗
PubMed1999

Alterations in pulmonary function following exercise are not caused by the work of breathing alone.

Both pulmonary function and respiratory muscle strength decrease following exercise in healthy humans. The alterations in respiratory muscle are not the same following exercise and voluntary isocapnic hyperpnea that simulates that exercise. Therefore, in this study we measured pulmonary and respiratory muscle function following maximal exercise or hyperpnea that simulated the ventilation seen during exercise. Forced vital capacity (FVC), forced expiratory volume in 1 sec (FEV1.0), maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP) and handgrip strength were measured before and following voluntary hyperpnea in which minute ventilation and breathing frequency were controlled to levels identical to those obtained during the exercise test, and before and following a period of rest of equal duration to the exercise and hyperpnea tests. FVC decreased by 400 ml (7%, p<0.05) immediately post-exercise. MIP decreased by 12 mmHg (15%, p < 0.005) following exercise and remained depressed for 15 minutes. Neither MEP nor FEV1.0 decreased following exercise, and none of the variables were altered following the control or hyperpnea bouts. These data indicate that pulmonary function and respiratory muscle strength are altered following exercise but not by similar bouts of hyperpnea without accompanying exercise. Therefore, exercise affects pulmonary function independent of the respiratory muscle work done.

Adult↗