scholarly journals NOTA SUI LIMITI FISIOLOGICI DELLE IMMERSIONI PROFONDE IN APNEA

Author(s):  
Guido Ferretti

This article discusses the limits of deep breath-hold diving in humans. After a short historical introduction and a discussion of the evolution of depth records, the classical theories of breath-hold diving limits are presented and discussed, namely that of the ratio between total lung capacity and residual volume and that of blood shift, implying an increase in central blood volume. Then the current vision is introduced, based on the principles of the energetics of muscular exercise. The new vision has turned the classical vision upside down, moving the discussion to a different level. A direct consequence of the new theory is the importance of having large lung volumes at the start of a dive, in order to increase body oxygen stores. I finally discuss the role of anaerobic lactic metabolism as a possible mechanism of oxygen preservation, thus prolonging breath-hold duration.

1973 ◽  
Vol 82 (1) ◽  
pp. 89-95 ◽  
Author(s):  
Wilbur J. Gould ◽  
Hiroshi Okamura

It has long been assumed that the superior vocal ability of the trained professional singer arose from a higher than average breathing capacity and consequent above-normal ventilatory efficiency. However, until now, it has not been clear whether this presumed superior pulmonary capacity and breathing efficiency arose from training, from heredity, or from other factors. To clarify the role of training (and by inference that of other factors also) upon the capacity for singing, various indices reflecting static lung volumes, as distinguished from dynamic parameters measured during the act of singing, in trained professional singers, students of voice and subjects with no vocal training, were compared. Results indicated that contrary to reports by others, there were no significant differences in the total lung capacity (TLC) of the trained professional singer and that of the other two groups when allowances were made for age and sex; but when the ability to mobilize or utilize TLC was compared, it was found that the trained singer was much better able to do this than either of the other two groups. Specifically, it was found that the ratio of the residual lung volume (RV) (the amount of air remaining in the lungs at the end of a total voluntary expiration) to TLC was lower in the trained singer than in the students of voice, and that these students, in turn, had a lower RV/TLC ratio than the untrained subjects. These findings, therefore, suggest that the increased singing ability of the trained professional singer arises in large part from the ability to increase breathing efficiency by reducing the residual lung volume and, further, that this ability tends to improve with length of vocal training.


PEDIATRICS ◽  
1959 ◽  
Vol 24 (2) ◽  
pp. 181-193
Author(s):  
C. D. Cook ◽  
P. J. Helliesen ◽  
L. Kulczycki ◽  
H. Barrie ◽  
L. Friedlander ◽  
...  

Tidal volume, respiratory rate and lung volumes have been measured in 64 patients with cystic fibrosis of the pancreas while lung compliance and resistance were measured in 42 of these. Serial studies of lung volumes were done in 43. Tidal volume was reduced and the respiratory rate increased only in the most severely ill patients. Excluding the three patients with lobectomies, residual volume and functional residual capacity were found to be significantly increased in 46 and 21%, respectively. These changes correlated well with the roentgenographic evaluation of emphysema. Vital capacity was significantly reduced in 34% while total lung capacity was, on the average, relatively unchanged. Seventy per cent of the 61 patients had a signficantly elevated RV/TLC ratio. Lung compliance was significantly reduced in only the most severely ill patients but resistance was significantly increased in 35% of the patients studied. The serial studies of lung volumes showed no consistent trends among the groups of patients in the period between studies. However, 10% of the surviving patients showed evidence of significant improvement while 15% deteriorated. [See Fig. 8. in Source Pdf.] Although there were individual discrepancies, there was a definite correlation between the clinical evaluation and tests of respiratory function, especially the changes in residual volume, the vital capacity, RV/ TLC ratio and the lung compliance and resistance.


1978 ◽  
Vol 45 (6) ◽  
pp. 957-961 ◽  
Author(s):  
J. M. Drazen ◽  
S. H. Loring ◽  
C. Venugopalan

The effects of intravenous antigen infusion on lung volumes and quasi-static deflationary pulmonary compliance in guinea pigs previously sensitized to ovalbumin were studied in vivo. Ovalbumin infusion significantly increased minimal gas volume to a similar extent in animals with intact or cut vagi. Total lung capacity fell only in animals with intact vagi. Quasi-static compliance fell in both groups of animals, but the fall was significantly greater in animals with intact vagi. These data demonstrate that immediate hypersensitivity reactions alter lung volumes and the elastic properties of the lung by both vagal dependent and vagal independent mechanisms.


1983 ◽  
Vol 55 (2) ◽  
pp. 294-299
Author(s):  
H. W. Greville ◽  
L. J. Slykerman ◽  
P. A. Easton ◽  
N. R. Anthonisen

We studied the effect of volume history on airway closure in six healthy males ranging from 32 to 67 yr of age. The method used was to compare the regional distribution of 133Xe boluses distributed according to N2O uptake during open-glottis breath-hold maneuvers with the regional distribution of boluses of intravenously injected 133Xe. Measurements were made at two lung volumes, one close to residual volume (RV) and the other just below closing volume. The required volume was reached either by expiring from total lung capacity or by inspiring from RV. Although there was considerable airway closure in the basal regions of the lungs at both lung volumes studied, the degree of airway closure was not dependent on the previous volume history. We conclude that the airways concerned with closure have a volume-pressure hysteresis similar to that of the lung parenchyma. Furthermore in normal humans the volume-pressure hysteresis of the lung is not secondary to airway closure.


1961 ◽  
Vol 16 (2) ◽  
pp. 331-338 ◽  
Author(s):  
C. Emirgil ◽  
H. O. Heinemann

Fifteen patients, free from cardiac and pulmonary disease, but receiving radiotherapy for carcinoma of the breast or carcinoma of the lung, were studied to determine the effect of irradiation on pulmonary function. Lung volumes, the distribution of inspired air, the levels of gases in the arterial blood, the diffusing capacity of the lung, and the mechanics of breathing were measured before and at varying intervals after the completion of radiotherapy. The results showed: early and progressive reduction of inspiratory capacity (IC) and residual volume (RV), decreasing the total lung capacity (TLC) without changing the RV/TLC ratio; unchanged distribution of inspired air; mild hypoxemia at rest; reduced diffusing capacity of the lung for carbon monoxide; and an early and progressive decrease in pulmonary compliance. These observations indicate that irradiation of the chest is complicated by a decrease in lung volumes, an impairment of the diffusing capacity, and an increase in the work of breathing. Submitted on September 6, 1960


2006 ◽  
Vol 101 (3) ◽  
pp. 799-801 ◽  
Author(s):  
Leigh M. Seccombe ◽  
Peter G. Rogers ◽  
Nghi Mai ◽  
Chris K. Wong ◽  
Leonard Kritharides ◽  
...  

One technique employed by competitive breath-hold divers to increase diving depth is to hyperinflate the lungs with glossopharyngeal breathing (GPB). Our aim was to assess the relationship between measured volume and pressure changes due to GPB. Seven healthy male breath-hold divers, age 33 ( 8 ) [mean (SD)] years were recruited. Subjects performed baseline body plethysmography (TLCPRE). Plethysmography and mouth relaxation pressure were recorded immediately following a maximal GPB maneuver at total lung capacity (TLC) (TLCGPB) and within 5 min after the final GPB maneuver (TLCPOST). Mean TLC increased from TLCPRE to TLCGPB by 1.95 (0.66) liters and vital capacity (VC) by 1.92 (0.56) liters ( P < 0.0001), with no change in residual volume. There was an increase in TLCPOST compared with TLCPRE of 0.16 liters (0.14) ( P < 0.02). Mean mouth relaxation pressure at TLCGPB was 65 (19) cmH2O and was highly correlated with the percent increase in TLC ( R = 0.96). Breath-hold divers achieve substantial increases in measured lung volumes using GPB primarily from increasing VC. Approximately one-third of the additional air was accommodated by air compression.


1993 ◽  
Vol 36 (3) ◽  
pp. 516-520 ◽  
Author(s):  
Jeannette D. Hoit ◽  
Nancy Pearl Solomon ◽  
Thomas J. Hixon

This investigation was designed to test the hypothesis that voice onset time (VOT) varies as a function of lung volume. Recordings were made of five men as they repeated a phrase containing stressed /pi/ syllables, beginning at total lung capacity and ending at residual volume. VOT was found to be longer at high lung volumes and shorter at low lung volumes in most cases. This finding points out the need to take lung volume into account when using VOT as an index of laryngeal behavior in both healthy individuals and those with speech disorders.


1994 ◽  
Vol 77 (2) ◽  
pp. 963-973 ◽  
Author(s):  
D. D. Marciniuk ◽  
G. Sridhar ◽  
R. E. Clemens ◽  
T. A. Zintel ◽  
C. G. Gallagher

Lung volumes were measured at rest and during exercise by an open-circuit N2-washout technique in patients with interstitial lung disease (ILD). Exercise tidal flow-volume (F-V) curves were also compared with maximal F-V curves to investigate whether these patients demonstrated flow limitation. Seven patients underwent 4 min of constant work rate bicycle ergometer exercise at 40, 70, and 90% of their previously determined maximal work rates. End-expiratory lung volume and total lung capacity were measured at rest and near the end of each period of exercise. There was no significant change in end-expiratory lung volume or total lung capacity when resting measurements were compared with measurements at 40, 70, and 90% work rates. During exercise, expiratory flow limitation was evident in four patients who reported stopping exercise because of dyspnea. In the remaining patients who discontinued exercise because of leg fatigue, no flow limitation was evident. In all patients, the mean ratio of maximal minute ventilation to maximal ventilatory capacity (calculated from maximal F-V curves) was 67%. We conclude that lung volumes during exercise do not significantly differ from those at rest in this population and that patients with ILD may demonstrate expiratory flow limitation during exercise. Furthermore, because most patients with ILD are not breathing near their maximal ventilatory capacity at the end of exercise, we suggest that respiratory mechanics are not the primary cause of their exercise limitation.


1962 ◽  
Vol 17 (5) ◽  
pp. 783-786 ◽  
Author(s):  
John S. Hanson ◽  
Burton S. Tabakin ◽  
Edgar J. Caldwell

Variations in size of the various lung volumes due to changes in body position and as a consequence of treadmill exercise were studied in five normal males. Assumption of the upright posture was associated with highly significant increases in total lung capacity, vital capacity, expiratory reserve volume, and residual volume as compared to resting supine values. Level walking was associated with a decrease of expiratory reserve volume, but a further expansion of residual volume. Vital capacity decreased slightly, but total lung capacity increased by virtue of the proportionately large residual volume increases. Elevation of the treadmill to 4° resulted in slight decreases in all lung volumes, total lung capacity evidencing a barely significant decline. Positional changes in ventilation are described, and on the basis of the “lung clearance index” an increased efficiency of ventilation is seen in the upright posture. Factors possibly operative in these alterations are discussed. Submitted on February 21, 1962


1980 ◽  
Vol 49 (4) ◽  
pp. 558-565 ◽  
Author(s):  
N. Berend ◽  
C. Skoog ◽  
W. M. Thurlbeck

Static deflationary pressure-volume curves were obtained in 28 emphysema-free (18 male and 10 female) and 39 emphysematous excised human lungs inflated to a maximum transpulmonary pressure (Pl) of 30 cmH2O. In emphysema-free lungs, the lung volumes at Pl 30 cmH2O (V30) were significantly related to body length in males and were significantly larger than predicated total lung capacity in vivo. However, corrected for stature (V30/body length), there was no significant age correlation. In both males and females, highly significant correlations between the PL at 50--90% V30 and age were obtained. There were no significant differences in these regressions between males and females. The emphysematous lungs were divided into three groups with increasing emphysema grades. Progressive decreases in the PL at 50--90% V30 and increases in the V30 were seen in the groups with increasing degrees of emphysema. Significant changes occurred in these measurements even in group 2 with mild emphysema, suggesting that the lesions of emphysema are not directly responsible for these changes.


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