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Results for “Maximal Voluntary Ventilation”

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PubMed2000

Pulmonary function changes following surgical correction for pectus excavatum.

OBJECTIVE: To assess whether and to what extent pulmonary function returns to normal after surgical correction for pectus excavatum. METHODS: Twenty-seven patients who could be examined in person at the outpatient department of our hospital were included in this study. Of these patients, 24 were boys and 3 were girls, with age ranging from 3 to 16 years (mean: 8.67 years). The mean age at surgery was 4 years and mean years at follow-up was 6.8. Pulmonary function measurements included inspiratory vital capacity (IVC), total lung capacity (TLC), residual volume (RV), functional residual capacity (FRC), RV/TLC ratio, maximal voluntary ventilation (MVV), forced ventilatory capacity (FVC), forced expiratory volume in one second (FEV1), maximal mid-expiratory flow (MMEF), maximal expiratory flow at 75% vital capacity (V75), maximal expiratory flow at 50% vital capacity (V50), maximal expiratory flow at 25% vital capacity (V25) and breathing reserve ratio (BR). RESULTS: TLC, FRC, MVV, MMEF, V75 and V50 were not different from normal values. IVC, FVC, FEV1 and V25 were significantly decreased compared with normal values. RV and RV/TLC were high in 87.5% cases. CONCLUSIONS: Preoperative symptoms improved substantially after operation. Little airway obstruction was observed postoperatively, suggesting that patients with pectus excavatum should have surgery as early in life as possible, preferably by age 3.

Adolescent↗

PubMed2001

[Measurement of central respiratory drive and inspiratory muscles strength in patients with uremia].

OBJECTIVE: To investigate the changes of central respiratory drive and inspiratory muscles function in patients with uremia. METHODS: We performed the measurement of forced vital capacity (FVC), maximal voluntary ventilation (MBC), forced expiratory volume in one second (FEV1), peak expiratory flow (PEF), maximal midexpiratory flow (MMEF), expiratory flow of 25 per cent of FVC (V25), lung carbon monoxide diffusing capacity (DLco), maximal inspiratory mouth pressure (MIP) and airway occlusion pressure (P0.1) in 25 patients with uremia and 20 normal subjects. RESULTS: In patients with uremia, the FVC, MBC, FEV1, PEF, MMEF and V25 which reflect the lung ventilatory function and the DLco which reflects the lung diffusing function were significantly lower than those in normal subjects. The patients' MIP which reflects inspiratory muscles strength was significantly lower and their P0.1 which reflects the central respiratory drive was significantly higher, compared with the normal subjects'. CONCLUSION: Our findings suggest that on the basis of the disorder of ventilation and diffusing function of the lungs, the inspiratory muscles function of the patients with uremia is significantly decreased and the central respiratory drive of the patients is increased.

Aged↗

PubMed1985

Effect of eucapnic hypoxia on bronchomotor tone and on the bronchomotor response to dry air in asthmatic subjects.

Because hypoxia has been shown to cause bronchoconstriction and to potentiate bronchomotor responsiveness in animals, we investigated whether hypoxia has similar effects in subjects with asthma. We measured specific airway resistance (SRaw; the mean of 5 sequential readings taken 30 s apart) before and immediately after each of 15 asthmatic subjects breathed a mixture of 8% O2 in N2 until hemoglobin saturation (SaO2; by ear oximetry) fell to 80% or less for at least 2 min. We maintained end-tidal CO2 at resting levels, the temperature of the inspirate at 22.0 +/- 1.1 degrees C, and the dew point at 18.5 +/- 1.6 degrees C (mean +/- SD). The SaO2 fell to 70 +/- 8%; minute ventilation rose to 28.4 +/- 8.5 L/min, and heart rate rose by 27 +/- 6 beats/min. The SRaw did not increase significantly in the group (baseline SRaw, 6.61 +/- 2.36; posthypoxia SRaw, 6.69 +/- 2.21 L X cm H2O/L/s) or in any subject. To determine if hypoxia increases bronchomotor responsiveness, we also compared the responses to eucapnic hyperpnea with dry air and with dry gas mixtures of 7 to 10% O2 in N2 in a randomized, double-blind sequence in 9 of the subjects. We measured SRaw in each subject before and after stepwise increases in minute ventilation, for 3 min at each level, until SRaw doubled or until the subject's maximal voluntary ventilation was achieved. The SaO2 fell to 82% or less at each level of ventilation with the hypoxic gas mixture. The 2 stimulus-response curves thus obtained did not differ in any subject.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed2000

Effectiveness of the fold plication method in lung volume reduction surgery.

OBJECT: The fold plication method is a new operative procedure for lung volume reduction surgery whereby the target area is obliterated by plicating the folded tissue using a knifeless stapler, without the use of bovine pericardium. The effectiveness of this new method was evaluated in patients with advanced pulmonary emphysema. PATIENTS AND METHODS: Two weeks before and 6 months after surgery, pulmonary function, static lung compliance, maximal esophageal pressure, maximal inspiratory and expiratory mouth pressures, 6-min walking distance and the Borg scale were determined in twenty consecutive patients who underwent video-assisted thoracoscopic unilateral surgery. RESULTS: There was an increase in forced expiratory volume in one second (31%), forced vital capacity, peak expiratory flow rate and maximal voluntary ventilation, and a decrease in functional residual capacity (-16%) measured by plethysmograph. Static lung compliance decreased, and maximal esophageal pressure, and maximal inspiratory and expiratory mouth pressures increased. The 6-min walking distance increased (20%) and the Borg scale decreased (5.9 to 3.5). CONCLUSION: The results compare favorably with those obtained with other methods. Thus, the fold plication method could be considered an alternative procedure for lung volume reduction surgery.

Aged↗

PubMed1990

Evaluation of conventional weaning criteria in patients with acute respiratory failure.

We evaluated the reliability of conventional weaning criteria from a ventilator during 33 weaning trials on 25 patients with acute respiratory failure (ARF). Of 13 criteria, a ratio of maximal voluntary ventilation to minute ventilation (MV) >2, a vital capacity >12 ml.kg(-1), a spontaneous respiratory rate <25 breaths.min(-1), and a MV <10 l.min(-1) appeared to be useful for predicting successful weaning outcome. However, even using those criteria, there were many falsely-negative cases. The alveolar-arterial P(O)(2) gradient <350 mmHg at an F i(O)(2) 1.0 was not useful as a predictor of weaning outcome. The present study demonstrates that conventional criteria are frequently inaccurate for predicting weaning outcomes and suggests that the use of some of these criteria may unnecessarily prolong the length of ventilator support. Since ventilation of most patients with poor oxygenation can be successfully discontinued by placing them on a continuous positive airway pressure system, these results suggest that the improvement of oxygenation is not an indispensable prerequisite for weaning from mechanical ventilators.

Journal Article↗

PubMed1987

The effect of sleep loss on breathing in chronic obstructive pulmonary disease.

We have previously shown that one night of sleep deprivation results in significant deterioration of spirometric performance and ventilatory responsiveness to inhaled carbon dioxide in normal people. Since even a small decrease in pulmonary function may be clinically important in patients with chronic limitation of airflow, we undertook the present study to assess the effects of sleep loss on breathing in patients with chronic obstructive pulmonary disease (COPD). Criteria for inclusion in this study were a ratio of the forced expiratory volume in one second over the forced vital capacity (FEV1/FVC) of less than 60 percent, no hospital admission for pulmonary disease within two weeks of testing, stable (less than 30 percent variation) in tests of pulmonary function on two occasions within three months of testing, and no history of asthma. We studied 15 men (mean age, 57 +/- 3 years) on two consecutive mornings. Patients were studied with and without sleep deprivation in a randomized fashion. Patients were hospitalized for the study so that sleep deprivation, medications, smoking, and diet could be monitored and enforced. We found small but statistically significant falls in FEV1 (1.06 +/- 0.11 to 1.00 +/- 0.09 L; p less than 0.05) and in FVC (2.56 +/- 0.20 to 2.43 +/- 0.17 L; p less than 0.05) following sleep deprivation. Changes of similar magnitude which were not statistically significant occurred in maximal voluntary ventilation (MVV) and response to carbon dioxide. The arterial oxygen (PaO2) and carbon dioxide (PaCO2) tensions were not affected. Maximal expiratory pressure at the mouth increased slightly, but there was a fall in maximal inspiratory pressure (MIP) at the mouth. We conclude that sleep loss is associated with small but significant falls in FEV1 and FVC, as well as changes of similar magnitude in MVV, minute ventilation, and MIP in patients with severe COPD. Although the sleep loss which frequently accompanies exacerbations of COPD may be a slight additional stress of pulmonary reserve, a single night's loss of sleep in the patient with stable chronic airflow obstruction does not have major clinical consequences.

Aged↗

PubMed1992

Ventilatory capacity and exercise-induced arterial desaturation of highly trained endurance athletes.

Recent evidence suggested that exercise-induced arterial O2 desaturation may occur in highly trained endurance athletes. So, Dempsey brought the hypothesis that the pulmonary capacity for oxygen transport cannot meet superior demands imposed by cardiovascular system in highly trained endurance athletes, and endurance training primarily causes adaptation in the skeletal muscles and in the systemic cardiovascular system, with little change in the pulmonary system. In the present study, we determined the propriety of the hypothesis due to measure the ventilatory capacity of endurance athletes. Sixteen highly trained endurance athletes (ET) and thirteen untrained subjects (UT) volunteered to participate in these experiments. All subjects performed the four experiments, 1) the highest oxygen uptake (peak VO2) during incremental cycle exercise and ventilation (VE), ventilatory equivalent for O2 (VE/VO2) and arterial O2 saturation (SaO2) at which peak VO2 was observed, 2) the maximal voluntary ventilation for 30 sec at rest (MVV), 3) the pulmonary diffusing capacity for CO (DLCO) and expressed per unit of alveolar lung volume (KCO) at rest by the single breath method, and 4) the ventilatory response to hypercapnia (S) at rest by rebreathing method, were measured. The peak VO2 of ET (66.7 ml.min-1.kg-1) was significantly (30.8%) higher than UT (52.4 ml.min-1.kg-1), and VE/VO2 and SaO2 of ET (29.3 and 93.7%, respectively) were significantly lower than UT (34.6 and 95.8%). There were no differences in VE, MVV, DLCO, and S between two groups.

Adult↗

PubMed1999

Body composition analysis by dual energy X-ray absorptiometry and exercise performance in underweight patients with COPD.

STUDY OBJECTIVES: The aim of this study was to examine the effect of body composition on maximal exercise performance in patients with COPD. METHODS: The study was carried out on 27 patients with COPD and was confirmed by pulmonary function testing. Body composition was measured by dual energy x-ray absorptiometry (DXA). Exercise performance was conducted on a cycle ergometer and was measured as maximal work rate (WRmax) and maximal oxygen uptake (VO2max). Bone mineral content (BMC), lean mass (LEAN), and fat mass (FAT) were assessed by DXA and were expressed as a percentage of ideal body weight, BMC, LEAN, and FAT. RESULTS: LEAN% correlated significantly with VO2max (r = 0.66, p = 0.0002) and WRmax (r = 0.70, p < 0.0001). No significant correlation was found between FAT% and exercise performance. By stepwise regression analysis, variables significantly contributing to WRmax and VO2max were LEAN% and the maximal voluntary ventilation. Total variance explained in these models was 81% for WRmax aid 82% for VO2max. CONCLUSION: Lean mass was an important determinant of maximal exercise performance in patients with COPD.

Absorptiometry, Photon↗

PubMed1984

A summary of preoperative and postoperative cardiorespiratory performance in patients undergoing pectus excavatum and carinatum repair.

Preoperative and postoperative pulmonary function tests and progressive work exercise performances were compared for fourteen pectus excavatum and five pectus carinatum patients who underwent operative repair. No changes could be documented in the pectus carinatum patients. The excavatum patients demonstrated a small improvement in total lung capacity (P less than .02) and a significant improvement in maximal voluntary ventilation (P less than .001). In addition, the exercise performances were improved for the excavatum patients postoperatively as quantitated both by the total exercise time and the maximal oxygen consumption (P less than .01). In addition, at any given work rate, the excavatum patient demonstrated a lower heart rate and higher minute ventilation after operation. These findings support the hypothesis that both the restricted cardiac stroke volume and the increased work of breathing that have been described in pectus excavatum patients can be ameliorated by operative intervention.

Adolescent↗

PubMed1996

[Acute effect of lorazepam on respiratory muscles in stable patients with chronic obstructive pulmonary disease].

Benzodiazepines are known to cause muscle hypotonia, but their effects on respiratory muscle function, particularly on diaphragm, have not yet been studied. Our aim was to look for any effect of lorazepam on respiratory muscle function in patients with chronic obstructive pulmonary disease (COPD). Nine stable COPD patients (mean +/- SD forced expiratory volume in one second (FEV1) 0.91 +/- 0.31 l) were included in the study. The following measurements were performed before and 1 hour after lorazepam administration (doses: 1.5 to 2 mg) by sublingual route: forced vital capacity (FVC), FEV1, maximal voluntary ventilation (MVV), arterial oxygen tension (PaO2), arterial carbon dioxide tension (PaCO2), minute ventilation (Ve), tidal volume (Vt), respiratory rate (f), inspiratory time/inspiratory plus expiratory time (Ti/Ttot)-, mean inspiratory flow (Vi), maximal inspiratory (MIP) and expiratory (MEP) pressures, maximal pleural pressure (Pplmax), transdiaphragmatic pressures (Pdi) and skeletal muscle strength and endurance. As expected, no change was noted in FVC, FEV1, FEV1/FVC (Table-1). Besides stability of expiratory flows, this denotes no change in collaboration in spite of the sedative effects of lorazepam. There was a 20% decrease in Ve, due to a Vt reduction and a small increase in PaCO2. These could be explained by the central effects of benzodiazepines. Skeletal muscle strength and endurance decreased significantly (22 and 50% respectively-Table 2), in accordance with the previously reported muscular actions of this pharmacological group. Respiratory muscle function parameters, MIP, MEP, MVV and Ppl showed significant reductions (10 to 20 per cent), as was the case with diaphragmatic function measured by Pdi (Muller maneuver with abdominal protrussion and maximal open-glottis expulsive maneuver) (Table 3). This study demonstrates that a single lorazepam dose reduces strength and endurance of respiratory muscle in chronic stable COPD patients.

Female↗

PubMed2003

Influence of isocapnic hyperpnoea on maximal arm cranking performance.

Isocapnic hyperpnoea has been shown to reliably produce fatigue of the diaphragm. The aim of the present study was to investigate whether incremental isocapnic hyperpnoea (IH(incr)) impairs the arm exercise performance and alters the breathing pattern during subsequent maximal incremental arm cranking. Nine healthy volunteers performed an arm cranking test with prior IH(incr) (AC(IH)) and without prior IH(incr) (AC(control)). Minute ventilation ( V(E)), tidal volume ( V(T)), breathing frequency ( f(b)), O(2) uptake ( VO(2)), CO(2) elimination ( VCO(2)), respiratory exchange ratio (RER) and end-tidal partial pressure of CO(2) ( P(ET)CO(2)) were measured at three different time intervals ( t(1): the average of the 3.30th min to the 6.30th min, t(2): 1 min before the end, t(3): peak value) and expressed as mean (SD). V(T) at t(1) and at t(3) was significantly ( P<0.05) lower during AC(IH) [AC(control): t(1): 1.3 (0.5) l, t(p): 1.9 (0.3) l; AC(IH): t(1): 1.1 (0.3) l, t(p): 1.6 (0.3) l]. f(b) at t(1) and t(2) was significantly ( P<0.05) higher during AC(IH) [AC(control): t(1): 23 (4) breaths min(-1), t(2): 42 (14) breaths min(-1); AC(IH): t(1): 27 (5) breaths min(-1), t(2): 48 (14) breaths min(-1)]. The maximal voluntary ventilation (MVV), measured before and immediately after the IH(incr), demonstrated a small but significant decrease from 157 (15) l min(-1) to 150 (14) l min(-1) ( P<0.05) after the IH(incr). In conclusion, rapid shallow breathing occurred during maximal arm cranking exercise after IH(incr). The alteration was irrespective of the workload and had already occurred at the start of exercise.

Adult↗

PubMed2005

Alveolar-capillary membrane conductance is the best pulmonary function correlate of exercise ventilation efficiency in heart failure patients.

BACKGROUND: In heart failure (HF), changes in lung mechanics and gas diffusion are limiting factors to exercise. Their contribution to an increased exercise ventilation to CO2 production (VE/VCO2) slope is undefined. METHODS: A total of 67 stable HF patients underwent cardiopulmonary exercise and pulmonary function tests, including forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), maximal voluntary ventilation (MVV), total lung capacity (TLC) and alveolar diffusing capacity with its subcomponents (alveolar-capillary membrane conductance (D(m)) and capillary blood volume (V(c))). RESULTS: Patients showed a mild restrictive pattern (FEV1=85+/-15% and FVC=75+/-13% of normal predicted) and a moderate D(m) reduction (32+/-12 ml min(-1) mm Hg(-1)). Average peak VO(2) was 15.6+/-4.0 ml min(-1) kg(-1) and the VE/VCO2 slope was 39.6+/-11.0. At simple Spearman correlation analysis, all variables, but V(c), correlated with peak VO2; only D(m) correlated with VE/VCO2 slope. At partial Spearman correlation, all variables lost the peak VO2 correlation, and D(m) still inversely correlated with VE/VCO2 slope (r=-0.35; p=0.005). In patients with a high VE/VCO2 slope (cutoff value 34), despite comparable lung volumes, D(m) was significantly more depressed (30+/-13 vs. 35+/-10 ml min(-1) mm Hg(-1); p<0.01). CONCLUSIONS: Pulmonary function tests and alveolar gas diffusing capacity poorly correlate with peak VO2. D(m) impairment rather than lung volumes correlates with exercise ventilation efficiency. This finding further adds to the pathophysiological relevance of an abnormal gas exchange in HF patients.

Aged↗

PubMed1996

Effects of chemical defense clothing and individual equipment on ventilatory function and subjective reactions.

BACKGROUND: We hypothesized that the multiple layers of protective clothing (PC) of a Chemical Defense Uniform (CDU) with body armor (BA), and load bearing equipment (LBE) impose an external impedance on breathing mechanics in addition to that caused by the chemical-biological protective mask (CB mask). METHODS: We measured the effects of wearing the CDU with BA + LBE on the mechanics and pattern of breathing and subjective reactions in 15 male soldiers during rest and sustained exercise (600 W). Heat strain on each soldier was made minimal and equivalent between the battle dress uniform (BDU) and CDU configurations. RESULTS: Results from wearing the CDU were contrasted with data from wearing a physical training uniform (PTU), or BDU. At rest, the CDU decreased maximal voluntary ventilation (MVV) by 25% (p < 0.05) compared with the PTU. The CB mask alone reduced MVV 20% (p < 0.05), and the PC + BA + LBE components of the CDU contributed an additional 5% decrement (p = 0.059). The CB mask decreased maximal respiratory flows (p < 0.05), whereas the PC + BA + LBE components decreased lung volumes (p < 0.05), and potentiated the decrement of respiratory flows. Total respiratory system elastance (Ers) was increased by 16% (p < 0.05) in the CDU. During exercise, VE was comparable for both the CDU and BDU, but VT was smaller (p < 0.01) and fR greater (p < 0.05) in the CDU; a breathing pattern consistent with the increased Ers. Perceptions of anxiety, not getting enough air, not breathing the way one usually does, and not being relaxed were greater (p < 0.05) during exercise in the CDU than in the BDU. CONCLUSIONS: This study shows that some of the respiratory impairment associated with the wearing of CDU is created by the PC, BA and LBE which present a unique external constraint on the chest wall. These impairments to ventilation may provoke more aversive effects than the larger resistive loads imposed by the CB mask.

Adult↗

PubMed1996

Role of neutral endopeptidase in exercise-induced bronchoconstriction in asthmatic subjects.

The membrane-bound metalloproteinase, neutral endopeptidase (NEP), is a degrading enzyme of both bronchoconstrictor and bronchodilator peptides within the airways. To examine the role of NEP in exercise-induced bronchoconstriction (EIB) in asthmatic subjects, we used inhaled thiorphan, a NEP inhibitor, as pretreatment to a 6-min standardized exercise challenge. Thirteen clinically stable asthmatic subjects participated in this double-blind, placebo-controlled, crossover study that was performed on 2 days separated by 48 h. Thiorphan was administered by two inhalations of 0.5 ml containing 1.25 mg/ml. Subsequently, exercise was performed on a bicycle ergometer at 40-50% of predicted maximal voluntary ventilation while inhaling dry air (20 degrees C, relative humidity 6%). The airway response to exercise was measured by forced expiratory volume in 1 s (FEV1) every 3 min, up to 30 min postexercise challenge, and was expressed both as the maximal percent fall in FEV1 from baseline and as the area under the time-response curve (AUC) (0-30 min). The acute effects of both pretreatments on baseline FEV1 were not different (P > 0.2), neither was there any difference in maximal percent fall in FEV1 between thiorphan and placebo (P > 0.7). However, compared with placebo, thiorphan reduced the AUC by, on average, 26% [AUC (0-30 min, +/-SE): 213.6 +/- 47.7 (thiorphan) and 288.6 +/- 46.0%fall.h (placebo); P = 0.047]. These data indicate that NEP inhibition by thiorphan reduces EIB during the recovery period. This suggests that bronchodilator NEP substrates, such as vasoactive intestinal polypeptide or atrial natriuretic peptide, modulate EIB in patients with asthma.

Administration, Inhalation↗

PubMedDate not supplied

The dose-response relationship in older men exposed to ozone.

Nine male subjects (56-71 years) were exposed to filtered air (FA) or 0.45 ppm O3 with inhaled dose altered by varying ventilation volume (VE = 25, 40, or 55 L/min (BTPS)) to evaluate pulmonary function dose-responses in older men. The subjects walked on a motor-driven treadmill and rested in alternating 20-min periods during the 2-h exposures. Functional residual capacity and maximal voluntary ventilation (MVV) were measured pre- and postexposure. Forced expiratory volume in 1 s (FEV1.0) and forced expiratory flow rate between 25% and 75% of vital capacity (FEF25-75%) were calculated from FVC. Residual volume (RV) was calculated from FRC. VE was measured during the last 4 min of each exercise period, and the electrocardiogram was monitored throughout each exposure. There were no significant changes in any measured parameter with FA exposure. All three O3 exposures induced small, statistically significant decrements in FVC and FEV1.0, but no significant changes in FEF25-75%. There were no significant differences among responses to the three O3 exposures. The decrements in measured pulmonary functions were smaller than typically observed in young males exposed to similar inhaled doses of O3. The data suggest possible saturation of the pulmonary response mechanism at a low degree of functional impairment in older men. Reflex-mediated impairment of inspiration, with concomitant reduction in all dependent pulmonary functions has been suggested as the mechanism of pulmonary dysfunction with O3 exposure in young adults. The results suggest that this reflex may be less active in older adults.

Administration, Inhalation↗

PubMed1993

Effects of flow and resistive training on respiratory muscle endurance and strength.

This study was conducted to ascertain whether resistive or flow type training would better improve both strength and endurance in the respiratory muscles of healthy subjects. Subjects performed a battery of respiratory strength and endurance tests before and after training, which consisted of either control, cycling exercise (E), inspiratory loading (IL), expiratory loading (EL), or hyperventilation (H) training for 4 weeks. Maximal sustained ventilation increased after training in the E and H groups. Both IL and H improved inspiratory fatigue resistance. IL improved maximal inspiratory pressure. No significant changes were found in maximal expiratory pressure although E, EL, and H tended to improve. There was no statistical difference in maximal voluntary ventilation between groups after training, but the H group alone did increase. This study suggests that respiratory muscle strength and endurance can be improved with flow or resistive training. Flow type training improves both flow and resistive tests while resistive training appears to affect only strength and resistive type measurements.

Adult↗

PubMed1999

Sniff nasal pressure: a sensitive respiratory test to assess progression of amyotrophic lateral sclerosis.

Impairment of pulmonary function is a major prognostic indicator in amyotrophic lateral sclerosis (ALS). Forced vital capacity (FVC) and maximal voluntary ventilation (MVV) decline linearly and are commonly used to assess disease progression. The aim of this study was to evaluate the usefulness of testing respiratory muscle strength in ALS with a novel test, sniff nasal pressure (Pn(sn)), in parallel with more classic tests such as maximal inspiratory pressure (PI(max)) and maximal expiratory pressure (PE(max)). Sixteen patients with ALS were examined monthly over a period of 18 +/- 10 months. At the time of inclusion in the study, values were normal for FVC (107% of predicted value) and MVV (87% of predicted value) but abnormally low for Pn(sn) (67% of predicted value), PI(max) (69% of predicted value), and PE(max) (54% of predicted value). Late in the course of ALS, all patients could perform Pn(sn) whereas 6 could not perform PI(max) and 7 could not perform PE(max). The rate of deterioration was most often linear and similar for FVC (-4.1% of predicted value per month), MVV (-4.3% of predicted value per month), and Pn(sn) (-4.2% of predicted value per month). We conclude that Pn(sn) was the single respiratory test combining linear decline, sensitivity in mild disease, and feasibility in advanced disease. Being easy to perform and inexpensive, Pn(sn) appears well suited to assess the decline of respiratory muscle strength in ALS.

Adult↗

PubMed1989

Late sequelae of lung contusion.

Twenty-four patients with severe lung contusion and multiple rib fractures were studied at a mean 4.9 years (range 2-9 years) after injury. All patients had been in good health before the accident. After the accident 15 (63 per cent) patients had respiratory symptoms such as dyspnoea at rest or moderate exercise (4), pain (8), cough or increased expectoration (11) and frequent bronchopulmonary infections (5). Three patients had changed their job because of respiratory disturbance. The average vital capacity, forced expiratory volume in 1 s, maximal voluntary ventilation and CO transfer factor were reduced respectively to 87, 88, 82 and 83 per cent of predicted values (P less than 0.01), while total lung capacity, residual volume and helium mixing time showed no definite changes (P greater than 0.05). Arterial blood gases at rest and at maximum exercise showed slight changes only. Maximal working capacity and ECG, as well as the ventilatory cost of moderate exercise were normal, where as the CO2 recovery time after moderate exercise was slightly increased (P less than 0.05). Overall there was a tendency towards poorer function in patients treated with artificial ventilation. Chest radiographs were normal in 10 patients (42 per cent), and moderate changes were seen in 14 patients. Diaphragmatic movements were essentially normal in all patients. Severe injury to the chest causes frequent respiratory symptoms. However, objective tests were only moderately reduced when compared with normal values. There was no unequivocal association between the subjective symptoms and the pulmonary function.

Adult↗