Higher Breathing Rate Research Articles

Analysis and compensation for errors in electrical impedance tomography images and ventilation-related measures due to serial data collection

Electrical impedance tomography (EIT) is increasingly being used as a bedside tool for monitoring regional lung ventilation. However, most clinical systems use serial data collection which, if uncorrected, results in image distortion, particularly at high breathing rates. The objective of this study was to determine the extent to which this affects derived parameters. Raw EIT data were acquired with the GOE-MF II EIT device (CareFusion, Höchberg, Germany) at a scan rate of 13 images/s during both spontaneous breathing and mechanical ventilation. Boundary data for periods of undisturbed tidal breathing were corrected for serial data collection errors using a Fourier based algorithm. Images were reconstructed for both the corrected and original data using the GREIT algorithm, and parameters describing the filling characteristics of the right and left lung derived on a breath by breath basis. Values from the original and corrected data were compared using paired t-tests. Of the 33 data sets, 23 showed significant differences in filling index for at least one region, 11 had significant differences in calculated tidal impedance change and 12 had significantly different filling fractions (p = 0.05). We conclude that serial collection errors should be corrected before image reconstruction to avoid clinically misleading results.

Estimation of Respiratory Rates Using the Built-in Microphone of a Smartphone or Headset.

This paper proposes accurate respiratory rate estimation using nasal breath sound recordings from a smartphone. Specifically, the proposed method detects nasal airflow using a built-in smartphone microphone or a headset microphone placed underneath the nose. In addition, we also examined if tracheal breath sounds recorded by the built-in microphone of a smartphone placed on the paralaryngeal space can also be used to estimate different respiratory rates ranging from as low as 6 breaths/min to as high as 90 breaths/min. The true breathing rates were measured using inductance plethysmography bands placed around the chest and the abdomen of the subject. Inspiration and expiration were detected by averaging the power of nasal breath sounds. We investigated the suitability of using the smartphone-acquired breath sounds for respiratory rate estimation using two different spectral analyses of the sound envelope signals: The Welch periodogram and the autoregressive spectrum. To evaluate the performance of the proposed methods, data were collected from ten healthy subjects. For the breathing range studied (6-90 breaths/min), experimental results showed that our approach achieves an excellent performance accuracy for the nasal sound as the median errors were less than 1% for all breathing ranges. The tracheal sound, however, resulted in poor estimates of the respiratory rates using either spectral method. For both nasal and tracheal sounds, significant estimation outliers resulted for high breathing rates when subjects had nasal congestion, which often resulted in the doubling of the respiratory rates. Finally, we show that respiratory rates from the nasal sound can be accurately estimated even if a smartphone's microphone is as far as 30cm away from the nose.

Effect of anxiety on the function of the cardiorespiratory system

The effects of anxiety on the external respiration system and respiratory sinus arrhythmia (RSA) were studied in healthy subjects in real-life conditions. Changes in external respiration parameters and heart rate variability (HRV) in students going to take their end-of-term exams were assessed relative to a midterm period, and the cardiorespiratory system was monitored in a longitudinal study for 50 days. The function of the cardiorespiratory system was characterized by measuring external respiration parameters and calculating HRV parameters. State anxiety (SA) was assessed using Spielberger’s scale. An increase in SA before an exam was accompanied by a higher breathing rate, a higher tidal volume, and lower HRV indices, especially those related to respiratory sinus arrhythmia (HF and HF norm). The changes in the parameters depended on the increase in SA. A negative correlation was observed between midterm HF and pre-exam SA. The longitudinal study revealed a distinct negative correlation between respiratory sinus arrhythmia parameters and peak expiratory flow (PEF) and a positive correlation between SA and PEF in the majority of subjects. Changes in cardiorespiratory parameters depended on the changes in SA in the longitudinal study. An increase in SA was accompanied by substantial changes in respiratory sinus arrhythmia (RAS) and external respiration parameters, and their correlation was assumed to indicate that modification of parasympathetic activity plays a leading role in increasing PEF.

Tracking lung tumour motion using a dynamically weighted optical flow algorithm and electronic portal imaging device

This paper investigates the feasibility and accuracy of using a computer vision algorithm and electronic portal images to track the motion of a tumour-like target from a breathing phantom. A multi-resolution optical flow algorithm that incorporates weighting based on the differences between frames was used to obtain a set of vectors corresponding to the motion between two frames. A global value representing the average motion was obtained by computing the average weighted mean from the set of vectors. The tracking accuracy of the optical flow algorithm as a function of the breathing rate and target visibility was investigated. Synthetic images with different contrast-to-noise ratios (CNR) were created, and motions were tracked. The accuracy of the proposed algorithm was compared against potentiometer measurements giving average position errors of 0.6 ± 0.2 mm, 0.2 ± 0.2 mm and 0.1 ± 0.1 mm with average velocity errors of 0.2 ± 0.2 mm s−1, 0.4 ± 0.3 mm s−1 and 0.6 ± 0.5 mm s−1 for 6, 12 and 16 breaths min–1 motions, respectively. The cumulative average position error reduces more rapidly with the greater number of breathing cycles present in higher breathing rates. As the CNR increases from 4.27 to 5.6, the average relative error approaches zero and the errors are less dependent on the velocity. When tracking a tumour on a patient's digitally reconstructed radiograph images, a high correlation was obtained between the dynamically weighted optical flow algorithm, a manual delineation process and a centroid tracking algorithm. While the accuracy of our approach is similar to that of other methods, the benefits are that it does not require manual delineation of the target and can therefore provide accurate real-time motion estimation during treatment.

Abstract 19585: Tidal Volume and Minute Ventilation Measurement at High, Low, and Erratic Respiratory Rates by a Non-Invasive Respiratory Monitoring System

Introduction: Changes in minute ventilation (MV) & tidal volume (TV) signal the beginning of respiratory compromise which often precedes cardiopulmonary arrest. Currently, respiratory monitoring in non-intubated patients lacks objective & quantitative methodology for determining the adequacy of ventilation. A non-invasive, Respiratory Volume Measurement (RVM) system has been developed to measure MV, TV and respiratory rate (RR) continuously. Previous work has demonstrated clinically acceptable accuracy and precision of RVM monitoring across normal respiratory patterns and rates. Hypothesis: RVM monitoring accurately yields tidal volume & minute ventilation across abnormal breathing rates, and erratic patterns. Methods: We studied 51 adult subjects (93 visits, 2252 tests) at low (4 - 6 bpm), normal (8 - 20 bpm), and high (30 - 40 bpm) respiratory rates and during erratic breathing. TV, RR and MV were measured simultaneously with an impedance-based RVM system (ExSpiron, Respiratory Motion, Inc., Waltham, MA) and a dry rolling seal spirometer (Morgan Scientific Inc., Haverhill, MA). Advanced data processing algorithms displayed a real time respiratory curve and calculated RVM measurements. Results: Throughout the range of 4 bpm to 40 bpm and during erratic breathing, RVM measurements are highly-correlated with spirometer measurements, with an average MV and TV correlation coefficient of 0.96, 95% CI 0.93 to 0.99 (Fig 1). Across all subjects, median correlation coefficients ranged from 0.91 to 0.99. Conclusions: High correlation (r = 0.96) between spirometric measurements and RVM signals concludes that the RVM system is capable of monitoring respiratory status during normal and erratic breathing, and at high and low breathing rates. As a passive, continuous, non-invasive system, RVM monitoring of non-intubated patients could provide earlier indications of respiratory decline potentially permitting interventions to prevent cardiopulmonary arrest.

Ventilatory equivalents for carbon dioxide and oxygen are measures of ventilatory efficiency and not of pulmonary gas exchange efficiency

Sin et al. (2010) have compared ventilatory equivalents for carbon dioxide and oxygen ( and , respectively) at two different breathing rates in healthy control subjects and patients with permanent cardiac pacemakers. In the healthy control group, reduction of breathing frequency from 15 to 6 breaths min−1 resulted not only in a 2.5-fold increase in respiratory sinus arrhythmia (RSA), but also in a significant reduction of and . In subjects with permanent cardiac pacemakers and therefore fixed-rate pacing, while there was no RSA, the reduction in and with reduction in breathing rate was similar to that in the healthy control subjects. The conclusion, therefore, is that there is improvement in gas exchange efficiency at the lower breathing rate, and this improvement is not contingent upon an enhancement of RSA. Our opinion is that and reflect ventilatory performance and not gas exchange efficiency. It is evident that these ratios will decrease with slow breathing (compared with a higher breathing rate) in any individual, irrespective of RSA, if the individual is asked to maintain end-tidal CO2 at a given value at both breathing rates (normocapnic range of 5–6% in this study), owing to an improved ratio of alveolar-to-dead space ventilation, resulting in lower minute ventilation. The effect of ventilation to perfusion ratio ( ratio) mismatch on gas exchange in a subject without RSA can be appreciated only by measuring the alveolar–arterial difference (A–a difference) and not by the parameters mentioned in the study. The authors themselves have stated that they chose not to study the three standard parameters for measuring gas exchange efficiency, including A–a difference, because these involve invasive procedures such as arterial or mixed venous blood sampling. It is clear, therefore, that the mechanism they refer to as pulmonary gas exchange is indeed the one assessed by A–a difference. However, cannot serve as a measure of gas exchange efficiency, in the sense conveyed in the paper, because carbon dioxide elimination will not be affected by temporal changes in ratios, as long as total ventilation and perfusion remain unchanged. Ventilation ( ) is a function of the arterial , and arterial is equal to end-tidal CO2. If the subjects are allowed to breathe voluntarily so as to maintain end-tidal CO2, as has been done in this study, reduction in breathing rate will not change , but will lead to lowering of because of less dead space ventilation at the lower breathing rate (Ganong, 2005), irrespective of the presence or absence of RSA. When decreases, the ventilatory equivalents estimated in this study will decrease. A decrease in A–a difference may occur in control subjects as a result of improved RSA when breathing rate is reduced, which may not be seen in the paced subjects. A reduction in A–a difference will lead to an increase in arterial and probably an increase in arterial and venous oxygen saturation in the control subjects. The lack of such an increase in oxygen saturation with slow breathing in paced subjects without RSA will not translate into any reduction in because oxygen consumption is a function of metabolic rate, and tissues can extract the required oxygen even from less saturated arterial blood.

Evaluation of a mask for breath‐by‐breath respirometry during exercise in horses

The ability to obtain breath-by-breath measures of ventilatory mechanics for the entirety of an exercise test, regardless of speed(s) or duration enables evaluations of equine ventilation during exercise that are necessary for assessments of performance. Evaluation of a new ergospirometer (Quadflow; QF) system's accuracy and repeatability for measuring pulmonary variables in contrast to the established pneumotachometer-based system (control) and assessment of its effects, if any, on exercise capacity at high speeds. Five Thoroughbred horses each performed 10 incremental exercise tests to fatigue, 5 with the QF system and 5 with an open-circuit flow system. Measures of pulmonary variables were evaluated to determine repeatability. Heart rate, pulmonary variables, arterial blood gases, distance run and time to fatigue measured with each system were compared to assess similarity of results and effect on performance. Results from both systems had high repeatability with low coefficients of variation. The QF was associated with greater resistance to airflow, higher breathing rate at submaximal speeds, lower minute ventilation and peak inspiratory and expiratory airflows, greater acidaemia, hypoxaemia and hypercapnoea, and decreased total run time and total distance run when compared to control system results. The greater resistance of the QF was responsible for altered blood gases, respiratory parameters and performance when compared to the control mask. The QF system reliably measured equine pulmonary airflows and volumes and is suitable for research and clinical use provided optimal gas exchange and best possible physical performance are not required.

Richtwerte für Benzylalkohol in der Innenraumluft

The German Working Group on Indoor Air Guidelines of the Federal Environment Agency and the States' Health Authorities is issuing indoor air guide values to protect public health. For health evaluation of benzyl alcohol in indoor air valid inhalation studies are missing. Following subchronic oral exposure to 800 mg benzyl alcohol/kg body weight and day neurotoxicity was observed in rats. Accounting for data gaps by a factor of 2 and extrapolating to continuous exposure by applying a factor of 2 the lowest adverse effect level for chronic exposure (LAELchron) is assessed as 200 mg benzyl alcohol/kg b. w. and day. By applying an interspecies factor of 10, an intraspecies factor of 10, a path-to-path-extrapolation and a modifying factor of 2 referring to the special physiology of children (higher breathing rate compared to adults) a health hazard guide value (RW II) of 4 mg benzyl alcohol/m3 indoor air and a health precaution guide value (RW I) of 0.4 mg benzyl alcohol/m3 are derived.

Optimal cycling and walking speed for minimum absorption of traffic emissions in the lungs

This study investigated whether, over a number of fixed distances and under a number of different exposure concentrations, the cyclist will adsorb less benzene by cycling/walking slowly with a relatively low breathing rate or by cycling/walking as fast as reasonably possible with a relatively high breathing rate. Breathing rates were measured in the laboratory for various cycling/walking speeds over set distances. These breathing rates could then be entered into a numerical model of the human respiratory tract together with the journey times and pollutant concentrations to assess the total absorption of pollutants in the lungs. Results show that cycling and walking at a relatively fast speed and therefore breathing at a higher rate over a shorter duration of exposure results in lower total absorption of benzene than cycling/walking the same distance at a slower speed. The magnitude of this reduction (was more notable at lower concentrations than at high concentrations in the alveolar region of the lungs and was more notable for the pedestrian than cyclist. The cycling at a faster pace resulted in a 17% reduction in total absorption, while walking at a faster pace resulted in a 26% reduction compared to travelling at a slower pace in both cases.

Experimental investigation of oscillatory air flow in a bronchial tube model with HFOV mode

Mechanical ventilations for artificial respiration have been developed to improve the medical treatment of the patients showing respiratory disorder. In various types of ventilation, High Frequency Oscillatory Ventilation (HFOV) is one of the most effective techniques of medical care for pulmonary disease patients, especially, infants or premature infants. HFOV is a ventilation technique with high breathing rate in comparison with the normal breathing rate. Some successful studies have focused on the effect of treatment using HFOV. However, the mechanism of gas exchange in bronchial tube under the medical treatment by HFOV has not been clarified. In this study, the oscillatory flow in a micro-channel model of bronchial with single bifurcation in HFOV mode has been investigated experimentally with micro Particle Image Velocimetry (micro PIV) technique. The phase averaged velocity profiles changing with the driving frequency of HFOV have been investigated.

Battle of the sexes: forcibly inseminating male garter snakes target courtship to more vulnerable females

In communal dens of garter snakes, Thamnophis sirtalis, in Manitoba, males obtain copulations forcibly, by inducing hypoxic stress in females. Females emerging from their 8-month winter inactivity are weak and slow, but recover strength and speed within a day or two of emergence. Thus, males may benefit by targeting newly emerged females that are too weak to resist, and by courting females under conditions that maximize the male’s physical advantage. Fieldwork at a Manitoba den supported these predictions. Both in the field and in outdoor enclosures, males focused courtship on to newly emerged (weak) rather than dispersing (postrecovery) females. Experimental trials showed that males based this choice on female skin lipids (pheromones) that predict time since emergence, rather than correlates of recent emergence that reflect female physiological state per se (low body temperature, low resistance to hypoxia, high breathing rates during courtship). Male superiority in locomotor speed was maximal at high temperatures, and males targeted courtship to hotter females. The postemergence recovery of females in this system substantially shifts the balance of power in physical encounters between males and females, and provides a fitness benefit to male ability to recognize and exploit more vulnerable females. Male ability to discern and exploit differentially vulnerable females is likely to be widespread, but less overt, in many other populations.

Breathing frequency and use of expiratory muscles do influence the dynamic positive end-expiratory pressure

End-expiratory air trapping due to obstructive airway disease can be estimated through the measurement of intrinsic positive end-expiratory pressure PEEP i. The influence of breathing-frequency and use of expiratory muscles on PEEP i were measured in 10 normal and 10 chronic bronchitic patients (COPD). Insignificant control values of PEEP i increased to measurable values at high breathing rate in normal subjects. Control values were higher in COPD patients and increased at fast breathing rate. When corrected for the use of expiratory muscles according to simultaneous gastric pressure drop, PEEP i decreased in COPD, but still increased at high rate. We conclude that modifying the respiratory rate can increase PEEP i values independently of the severity of airway obstruction and the use of expiratory muscles. Before estimating the pathological value of a PEEP i measurement or evaluating the effects of a treatment, we always need to know the simultaneous breathing frequency.

Occupational exposures in California wildland fire fighting.

Industrial hygiene measurement of exposures to wildland fire fighters was conducted in northern California during three consecutive fire seasons (1986-1989) in conjunction with three separate health effects studies. Chemicals that were monitored included carbon monoxide, total and respirable particulates, polyaromatic hydrocarbons (PAHs), crystalline silica, aldehydes, and benzene. Measurements were taken at both wildland fires and prescribed (planned) burns. A variety of collection methods were employed--colorimetric detector tubes and a CO monitor were used for direct-reading area measurements; colorimetric diffusion tubes, filter cassettes, sorbent tubes, and passive vapor monitors were used for determining personal time-weighted average exposures. A new screening method (National Institute for Occupational Safety and Health Method 2539) was used to identify the presence of specific aldehydes. Results show that wildland fire fighters may at times be exposed to concentrations of carbon monoxide, total or respirable particulates, or silica at levels near or higher than recommended occupational exposure limits, although group means were generally well below the limits. Time-weighted average formaldehyde levels, measured in a few instances above 0.37 mg/m3 (0.3 ppm), indicate a potential for formaldehyde-induced eye or respiratory irritation under these conditions. Certain characteristics of the work such as high altitude, temperature, and breathing rate; extended work shifts; and additional off-shift exposures suggest that adjustment of 8-hr exposure limits may be necessary to provide adequate protection. In part, because of the rigors of performing industrial hygiene measurements under fire fighting conditions, data are limited and could not be considered representative of the full range of exposures fire fighters may encounter.(ABSTRACT TRUNCATED AT 250 WORDS)

Heart rate variability analysis in full-term infants: spectral indices for study of neonatal cardiorespiratory control.

The heart rate and respirations of twenty healthy full-term infants between 30 and 60 h postnatal age were studied during quiet sleep with the objective of defining spectral indices which represent normal neonatal heart rate variability (HRV) characteristics. Total HRV power and the distribution of power across different frequency bands varied considerably among infants. Cluster analysis on the measured variables indicated that the population divided into two groups that represented significantly different patterns of HRV behavior. In one group (11 subjects), infants had lower breathing rates and HRV power in a band about the respiration frequency [respiratory sinus arrhythmia (RSA) band] was more than 20% of the total power (TP). Additionally, the ratio of low frequency band power to RSA band power was less than 4. The other group of neonates (nine subjects) had relatively higher breathing rates, RSA power less than 20% of total power, and low frequency to RSA power ratio greater than 4. Regression analysis of low frequency versus TP and RSA versus TP graphs gave strong support to the hypothesis that there were indeed two distinct patterns of HRV behavior. Separation of apparently normal neonates into two groups may be attributed partially to differences in respiratory rates and breathing patterns. However, it is possible that differences in the balance between sympathetic and parasympathetic nervous system control, perhaps related to autonomic maturation, also contribute to group separation. The indices developed from HRV spectral analysis in this investigation may be of value in the study of cardiorespiratory control in neonates.

Time course of adaptation to hypoxia in newborn rats

In newborn rats after a few minutes of hypoxia, ventilation is similar to the normoxic value. Nevertheless, after a few days in hypoxia, newborn rats have a sustained hyperventilation. In this study we examined the time course of the newborn rat's adaptation to hypoxia. Measurements of body size, hematocrit, lung and heart mass, and breathing pattern have been performed on newborn rats exposed to hypoxia (10% O2) for different time intervals from 4 to 60 h (hypoxic, H), and on same-age rats growing in air (controls, C). Ventilation measured by flow plethysmography was increased in H rats above the C value from about 8 h; this was due to a higher breathing rate and, from 24 h, also to a larger tidal volume. During the early hours of hypoxia, oxygen consumption measured manometrically was about 50% of C, while after 3 days in hypoxia it was almost like the C value. These observations indicate that the lack of sustained hyperventilation, characteristic of the newborn's acute exposure to hypoxia, is an immediate but transient phenomenon that is resolved after a few hours, and suggest a tight link between metabolic and ventilatory hypoxic responses. Body weight of H rats was less than in C, owing to an immediate decrease below the prehypoxic value. Dry heart and lung weight changed in proportion with the rest of the body during the first 36-48 h of hypoxia, then they increased disproportionately more. Hence, these temporal changes suggest that the large heart and lung weight-body weight ratios of the chronic hypoxic animals result from their smaller body mass and the stimulated growth of cardiac and pulmonary tissues.

Adaptation of airway stretch receptors in newborn and adult dogs

We studied the adaptive properties of tracheal and bronchial slowly adapting mechanoreceptors as an index of their dynamic responsiveness in newborn and adult dogs. The receptors studied exhibited a marked rate dependency in their adaptive characteristics: faster inflations leading to a higher adaptation, a behavior typically found in other mechanoreceptors. During inflatiions of comparable rate airway slowly adapting mechanoreceptors of newborn dogs reach initial firing rates (F i) that are lower than those of adult dogs. These increments in activity appear to be reduced in proportion to their lower static discharge (F s). Therefore when adaptation is represented as adaptation index (A.I. = (F i − F s)/F i × 100), i.e., in relative terms, it does not differ between age groups. Tracheal and bronchial slowly adapting mechanoreceptors do not differ in their adaptation for either of the age groups. In conclusion, since the dynamic sensitivity is lower in newborns, it cannot be a factor contributing to their higher breathing rate. Nevertheless, since newborns breathe faster than adults, the activation of their stretch receptors should be greater than it would have otherwise been, perhaps contributing to their faster rate of breathing.

Identifying critical human subpopulations by age groups: radioactivity and the lung

This work studies the effect of age on lung dose commitments arising from the inhalation of an atmosphere containing radionuclides of varying half-lives and physical sizes. This dependence is significant in many cases, approaching a ratio of 2 in several instances when the maximum dose at a given age is compared with that for an adult. In most instances, the maximum dose occurs between 4 and 8 years of age, due to a combination of small channel radii (allowing greater diffusional deposition), low lung mass, and high breathing rate. Age-dependence is largest for particles in the range 0.01 to 0.1 mu m, a range coincident with that normally encountered in atmospheric aerosols. Resting activity appears to provide the largest age-dependence, particularly for short-lived radionuclides. The study focused on radionuclides whose half-lives were less than 2 years. Total lung doses for longer lived radionuclides are dominated by pulmonary deposition and may be computed from the data in the figures, for a given knowledge of the transit times for the tracheo-bronchial region. From the present results, it appears likely that current maximum permissible levels of exposure to airborne radionuclides may require re-evaluation to ensure that children do not receive unacceptably large dose commitments. Further revision may be required upon the incorporation of age dependent risk factors.

Hypocapnia and measurement of airflow resistance and dynamic compliance as functions of respiratory frequency.

Measurements of lung mechanical behaviour as a function of respiratory frequency may be associated with significantly increased ventilation at high breathing rates. It follows that these measurements may be influenced by hypocapnia which has been shown to increase airflow resistance and to decrease dynamic compliance. To examine this possibility we continuously monitored the end-tidal CO2 tension during the determination of pulmonary resistance and dynamic compliance as functions of frequency and we compared measurements obtained by the standard method and by a technique designed to prevent the development of hypocapnia at high breathing rates. We studied 11 patients with chronic obstructive pulmonary disease and also two smokers with normal spirometry and resistance. Although conventional measurements at frequencies higher than 40-45 breaths/min were associated with a significant decrease in end-tidal CO2, no systematic differences were found between the values of pulmonary resistance and dynamic compliance obtained by the two techniques. Our data indicate that the development of hypocapnia at high breathing rates does not significantly affect measurements of resistance and compliance as functions of frequency, at least when the duration of each period of hyperventilation is limited to the minimum necessary for a single determination, which was less than 30 seconds in the present study. A comparison of our results with previously published data suggests that the time factor may be critical with respect to the possible effects of hypocapnia on these measurements.

Augmented diffusion in the airways can support pulmonary gas exchange.

Bohn et al. (J Appl. Physiol.: Respirat. Environ. Exercise Physiol, 48: 710-716, 1980) reported that paralyzed beagle dogs maintained normal gas exchange for 6 h or more when small tidal volumes at high breathing rates were maintained at the airway opening (15 ml tidal volume at 15 breaths/s). These tidal volumes were 25% of dead space and thereby were too small to permit convective gas exchange with pulmonary air spaces. I have used a semiempirical analysis to show that augmented diffusion in the central airways, akin to Taylor's turbulent dispersion (Proc. R. Soc. Ser. A 223: 446-468, 1954) combined with molecular diffusion in the periphery of the lung, can account for most if not all of the observed gas transport during small tidal volume, high-frequency ventilation. Ventilation efficiency (alveolar ventilation/minute ventilation) is approximately 2-5% and is insensitive to the combination of frequency and tidal volume giving rise to the minute ventilation.

Emotion, breathing and speech

The literature on the variations of respiration in different emotional states is extensive. Yet few studies have examined respiration during actual speaking because methods of measurement interfere with the production of speech or preclude it altogether. Observations on nonspeaking respiration in different emotional states include work by Finesinger [1], Deutsch [2] and others. Stevenson [3] found increases in the frequency and amplitude and a more irregular pattern in states of anxiety and, at times, anger. Clausen [4], working with a pneumograph, discriminated between groups of normal subjects and neurotics, finding in the latter a higher breathing rate. Christiansen [5] has recently reported similar findings in certain types of ‘excited’ psychiatric patients as compared with controls.