Pattern Of Breathing In Man Research Articles

The influence on the breathing pattern in man of moderate levels of continuous positive and negative airway pressure and of positive end‐expiratory pressure during air and CO2 inhalation

The purpose of this study was to determine in man the effect on the breathing pattern of continuous positive (CPAP), continuous negative (CNAP) and positive end-expiratory (PEEP) airway pressure during air breathing and CO2 inhalation. Six subjects were exposed to CPAP, CNAP and PEEP 0.5 kPa, while five subjects were exposed to CPAP and CNAP 0.8 kPa. End-expiratory lung volume increased during CPAP 0.8 kPa and decreased during CNAP 0.8 kPa. CPAP induced more extensive changes in the ventilatory pattern, and the changes in each parameter were larger than observed during CNAP and PEEP at the same pressure level. In contrast to previous reports we found the effect of CO2 inhalation combined with the effect of pressure breathing to be not stronger than additive. Even moderate CPAP induced alveolar hyperventilation with marked reduction in arterial PCO2 (PaCO2) when breathing air. With increasing fraction of CO2 in the inspiratory gas, the difference in PaCO2 between CPAP and no CPAP disappeared. PEEP also affected the breathing pattern in that it induced an increase in mean inspiratory flow and mean expiratory flow and a reduction in inspiratory duration. Occurrence of ventilatory pauses depended on whether mouthpiece or facemask was used. CPAP and CNAP did not influence the occurrence of pauses, while PEEP prolonged post-expiratory pauses. We conclude that CPAP, CNAP and PEEP induce active ventilatory responses in man and that strong mechanisms are involved during CPAP since PaCO2 is markedly reduced.

Effects of continuous positive- and negative-pressure breathing on the pattern of breathing in man during exercise.

Breathing pattern and static lung volumes were studied in 10 subjects at rest and during incremental-load cycle ergometry under three different conditions, viz. with normal pressure in the airways (control) and during continuous positive- and negative-pressure breathing (CPPB, CNPB) of +15 and -15 cmH2O. End-expiratory, end-inspiratory and mid-expiratory volumes were increased by CPPB and decreased by CNPB; these effects were especially pronounced at rest and during mild exercise. Both at rest and during exercise mean inspiratory flow (VT/TI) was exaggerated by CPPB and attenuated by CNPB. At rest these changes were due mainly to concomitant changes in tidal volume (VT) which was increased by CPPB and decreased by CNPB, while inspiratory time duration (TI) was relatively unaffected by pressure breathing. The transition from rest to loadless pedalling induced an increase in VT but no change in TI in the control condition, whereas in the CPPB and CNPB conditions TI decreased and VT remained unaltered. This CPPB- and CNPB-induced change in the volume-time threshold relationship at the onset of pedalling is attributed to increased stretch receptor activity in the extrathoracic portion of the trachea as a result of the increments in transmural pressure. During the course of exercise there was an inverse relationship between the slope of the VT-TI curve and the mid-expiratory volume in that the slope was greater in the control than in the CPPB condition and greatest during CNPB, suggesting that in exercise hyperpnoea the VT-TI relationship is also determined by pulmonary and/or thoracic wall stretch receptors capable of sensing the absolute lung volume.

Effects of exercise and CO2 inhalation on the breathing pattern in man

Conflicting opinions exist concerning the breathing pattern in man during resting and stimulated ventilation. Some but not all investigators have reported the existence of an abrupt change, a 'breakpoint', in the relation between mean tidal volume and mean inspiratory time. Different opinions exist as to whether the slope and the intercept for the relation between mean minute ventilation and mean tidal volume are identical regardless of the mode of stimulating the ventilation. We have studied 10 subjects, at rest and during graded stimulation of ventilation by CO2 inhalation and exercise. No breakpoint was observed in the relations between (1) mean tidal volume and mean inspiratory time and (2) mean tidal volume and mean expiratory time, even if a wide range of tidal volumes was achieved in our subjects. Carbon dioxide inhalation (normoxic or hyperoxic) and exercise gave different regression lines for the relation between mean minute ventilation and mean tidal volume in 8 out of 10 subjects with a larger slope during exercise. At exercise inspiratory time decreased with any increase in tidal volume, while during CO2 breathing no consistent change in inspiratory time was seen. Mean inspiratory flow was linearly related to exercise load and apparently also to arterial carbon dioxide pressure. We conclude that CO2 breathing gives a breathing pattern which is different from that obtained with exercise in the majority of normal subjects. Furthermore, we could not confirm the existence of breakpoints in relations describing the breathing pattern of normal man.

The pattern of breathing in man in response to sine waves of alveolar carbon dioxide and hypoxia.

Sine waves of alveolar CO2 at constant high alveolar O2, and sine waves of alveolar hypoxia (1/(PA, O2 -C) where C congruent to 32 torr) at constant alveolar CO2 have been administered to three subjects in each case. Six different periods of the sine waves were studied, ranging between 900 and 30 s for the CO2 sine waves and 300 and 20 s for the hypoxic sine waves. The sinusoidal variations in inspiratory and expiratory volumes (VT, I, VT, E), durations (TI, TE) and mean flows (vI, vE) produced by these manoeuvres were calculated, and the results analysed from the phase shifts of the responses. For the CO2 sine-wave results, the peak in the TI oscillation generally appeared after the minima for VT, I and vI, but before their maxima. The peak in the TE oscillation was variable. For the hypoxic sine-wave results, the peak in the TI oscillation showed no over-all tendency to lead or lag the peaks of VT, I and vI. The peak in the TE oscillation generally appeared after the maxima for VT, E and vE but before their minima. For the CO2 sine-wave results, expiratory mean flow led inspiratory mean flow, with the volumes showing no significant difference. For the hypoxic sine-wave results expiratory volumes and mean flows led inspiratory volumes and mean flows. The results are discussed in relation to the transient responses of the components of breathing pattern obtained from other perturbations of chemical drive.

The effects of sustained lung inflation on the pattern of breathing in man.

1. Continuous positive-pressure breathing (CPPB) at airway pressures of 0.65-1.00 kPa above ambient pressure has been used to produce a sustained inflation of the lungs of approximately 1 litre in six normal male subjects. 2. Lung inflation produced a reduction in the ventilatory response to carbon dioxide inhalation by slow rebreathing in oxygen over approximately 45 min, with a reduction in the slope of the VE/Pet,CO2 and VT/Pet,CO2 relations (Pet,CO2, = end-tidal PCO2). 3. The pattern of breathing is altered, so that for any given expired minute ventilation (VE), tidal volume (VT) is reduced with a fall in breath duration (Tt) resulting from a decrease in inspiratory time (Ti) with no change in expiratory time (Te). 4. The break point on the VT/Ti relation is lowered.

The effects of hypercapnia, hypoxia, exercise and anxiety on the pattern of breathing in man.

1. The pattern of breathing, defined as the relations between tidal volume and inspiratory and expiratory times, was measured during the stimulation of breathing by carbon dioxide (hyperoxic rebreathing at rest) in twenty-seven healthy, young volunteers. 2. Most of the patterns (twenty) were divisible into two parts, for low (range 1) and high (range 2) tidal volumes. The relations were curved, inverse proportionalities for both inspiration and expiration in range 2, and for expiration in range 1. The relations for inspiration in range 1 were evenly divided between those with constant inspiratory times (type 1) and those with curved, inverse proportionalities (type 2). 3. In four volunteers, direct proportionalities predominated and the patterns were scattered (type 3). 4. Eight of the volunteers (four type 1, two type 2 and two type 3 patterns) repeated the measurements and one changed from a type 1 to a type 2 pattern. 5. Nine of the volunteers also rebreathed during resting hypoxia. Two altered their patterns, and the others had patterns which were superimposed upon those measured during hyperoxic rebreathing at rest. 6. Eighteen of the volunteers also rebreathed (hyperoxic) during light exercise (25 W). Five entrained their breathing frequency to the exercise rhythm and showed exercise patterns with constant inspiratory and expiratory times. The others had patterns which were extensions of those measured during hyperoxic rebreathing at rest. 7. The pattern of breathing in range 1 was measured by steady-state methods in a further ten volunteers at rest with their eyes closed and open, and during mental arithmetic. The pooled average pattern showed that the stress of mental arithmetic shortened both inspiratory and expiratory times, and changed a type 2 pattern into a type 1 pattern.

Effects of body temperature on ventilatory response to hypoxia and breathing pattern in man.

The ventilatory response to hypoxia (PAO2 55 and 45 Torr) at each of four levels of PACO2 was studied in five healthy subjects before and after a rise in rectal temperature of 1.4 degrees C had been induced by means of a heated flying suit. At a given level of chemical drive both ventilation and mean inspiratory flow increased after heating, frequency relatively more than tidal volume. In isoventilation comparisons mean inspiratory flow was identical in normo- and hyperthermia, whereas the durations of inspiration (TI) and expiration (TE) were proportionately shortened. It is suggested that a rise in temperature shortens TI by affecting a central "clock" and that TE changes are secondary to changes in end-inspiratory volume. The euoxic CO2 response in hyperthermia was suggestive of multiplication between CO2 and temperature. Hypoxic sensitivity was significantly increased, indicating a temperature effect on the arterial chemoreceptors. The breathing pattern was in either temperature condition identical in euoxia and in hypoxia.

Mean and breath-by-breath pattern of breathing in man during steady-state exercise.

1. The breathing pattern, that is the relation between tidal volume (VT) and the inspiratory (TI) and expiratory (TE) durations, has been studied for individual breaths (forty in each steady state). 2. Five healthy subjects were studied in steady-state exercise on a bicycle ergometer breathing air; three of them were also studied in hypercapnia, at rest and during exercise, and two of them also during exercise on a treadmill. 3. Tidal volume and respiratory frequency both increased with work load. The increase in frequency was largely due to a progressive decrease in TE; TI also decreased. 4. At any constant level of respiratory drive (constant work load or chemical load) VT was positively correlated with both TI and TE in more than 95% of cases. 5. A simple model of the respiratory cycle which fits both the observed mean and breath-by-breath patterns and which involves no new assumptions is presented.

Immediate effects of positive-pressure breathing on the ventilatary response to CO2.

ArticleImmediate effects of positive-pressure breathing on the ventilatary response to CO2.D C Flenley, L D Pengelly, and J Milic-EmiliD C Flenley, L D Pengelly, and J Milic-EmiliPublished Online:01 Jan 1971https://doi.org/10.1152/jappl.1971.30.1.7MoreSectionsPDF (1 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByObstructive sleep apnea syndrome and asthma: the role of continuous positive airway pressure treatmentAnnals of Allergy, Asthma & Immunology, Vol. 101, No. 4Differential Inspiratory Muscle Pressure Contributions to Breathing during Dynamic HyperinflationAmerican Journal of Respiratory and Critical Care Medicine, Vol. 156, No. 2Measurements of PEEP-Induced Changes in Lung VolumeChest, Vol. 112, No. 1The influence on the breathing pattern in man of moderate levels of continuous positive and negative airway pressure and of positive end-expiratory pressure during air and CO 2 inhalationActa Physiologica Scandinavica, Vol. 138, No. 3Breathing Responses to Imposed Mechanical Loads1 January 2011Load compensation during positive pressure breathing in anesthetized manRespiration Physiology, Vol. 65, No. 3Effect of endotracheal continuous positive airway pressure on sensitivity to carbon dioxide and on respiratory timing in preterm infantsPediatric Pulmonology, Vol. 2, No. 2Therapy of Hyaline Membrane DiseaseRESPIRATORY MUSCLES RESPONSE TO LOADINGMuscle activity during chest wall restriction and positive pressure breathing in manRespiration Physiology, Vol. 35, No. 3Current Therapy in Hyaline Membrane DiseaseClinics in Perinatology, Vol. 5, No. 2EFFECT OF CONTINUOUS POSITIVE AIRWAY PRESSURE BREATHING ON CARDIORESPIRATORY FUNCTION IN INFANTS WITH RESPIRATORY DISTRESS SYNDROMEActa Paediatrica, Vol. 66, No. 1Some Steady-State Effects of Respiratory LoadsChest, Vol. 70, No. 1Occlusion pressure as a measure of respiratory center output cm conscious manRespiration Physiology, Vol. 23, No. 2Immediate ventilatory response to elastic loads and positive pressure in manRespiration Physiology, Vol. 18, No. 3A New Stimulant for Ventilatory Failure?The Lancet, Vol. 301, No. 7806The Role of the Intrinsic Properties of the Respiratory Muscles in the Regulation of VentilationChest, Vol. 61, No. 2The role of the vagus nerves in the respiratory response to CO2 under hyperoxic conditionsPfl�gers Archiv European Journal of Physiology, Vol. 336, No. 2 More from this issue > Volume 30Issue 1January 1971Pages 7-11 https://doi.org/10.1152/jappl.1971.30.1.7PubMed4249901History Published online 1 January 1971 Published in print 1 January 1971 Metrics

Role of ventilation in maintaining cardiac output under positive-pressure breathing.

ArticleRole of ventilation in maintaining cardiac output under positive-pressure breathing.J C Cruz, P Cerretelli, and L E FarhiJ C Cruz, P Cerretelli, and L E FarhiPublished Online:01 May 1967https://doi.org/10.1152/jappl.1967.22.5.900MoreSectionsPDF (851 KB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInEmailWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformationCited ByCardiac Output During Exercise: Contributions of the Cardiac, Circulatory, and Respiratory Systems1 January 2011The Pathophysiology of Hyperventilation DisordersChest, Vol. 109, No. 2The influence on the breathing pattern in man of moderate levels of continuous positive and negative airway pressure and of positive end-expiratory pressure during air and CO 2 inhalationActa Physiologica Scandinavica, Vol. 138, No. 3Influence of breathing frequency and the tidal volume on cardiac outputRespiration Physiology, Vol. 66, No. 2Regulation of human respiration under excessive intrapulmonary pressureBulletin of Experimental Biology and Medicine, Vol. 102, No. 2Pv̄O2, by nitrogen rebreathing — A critical, theoretical analysisRespiration Physiology, Vol. 16, No. 3Respiratory Variations of Blood Pressure in the Ox ( Bos Taurus ) During PantingBritish Veterinary Journal, Vol. 126, No. 12A critical evaluation of a nitrogen rebreathing method for the estimation of Pv̄O2Respiration Physiology, Vol. 10, No. 3 More from this issue > Volume 22Issue 5May 1967Pages 900-4 https://doi.org/10.1152/jappl.1967.22.5.900PubMed6025745History Published online 1 May 1967 Published in print 1 May 1967 Metrics

Airway resistance measurement during any breathing pattern in man.

A broadly applicable method for the quantitative and continuous measurement of airway resistance in man is described. It permits the simultaneous measurement of air flow (breath velocity) and alveolar pressure during any breathing pattern. Alveolar pressure is calculated from body plethysmograph pressure (plethysmogram) changes coincident with the compression and expansion of lung air during expiration and inspiration, respectively. The plethysmograph interior is maintained at body temperature and complete H2O saturation. This avoids the errors in measurement due to plethysmograph pressure changes produced by temperature and humidity changes in the inspired and expired breath and also obviates the necessity of using only a panting type breathing pattern. Data on three normal subjects at near resting and near maximum breathing efforts are presented and discussed. This improved method, permitting airway resistance measurements during any breathing pattern, should find application in diagnosis and assessment of treatment of pulmonary diseases as well as in the investigation of several basic pulmonary function problems. Submitted on June 17, 1958