Resting Breathing Rate Research Articles

Effect of Aerobic and Indigenous Training on Selected Physiological Variables

The present study aimed to examine the effect of specially designed aerobic activities andindigenous activities training program on selected variable of physiology. Total 45 female collegestudents were selected as the subject of the study. Resting heart rate, vital capacity and resting breathingrate were selected as the physiological variables. The selected subjected were divided into twoexperimental groups and one control group. Both experimental groups were given training for eightweeks. ANCOVA was used as statistical tool for the study. Result of the study showed that the aerobicactivities and indigenous activities training significantly improved heart rate and vital capacity. Whereasthere was no significant change observed in resting breathing rate.

Neural and Psychological Mechanisms in the Relationship Between Resting Breathing Rate and Pain

Neural and Psychological Mechanisms in the Relationship Between Resting Breathing Rate and Pain

The Resting Breathing Rate of the Dinosaur Plateosaurus trossingensis via Conservation of Energy

Conservation of energy is one of the foundations of science, and in this paper, we use this principle to estimate the resting breathing rate of the dinosaur Plateosaurus trossingensis (see Fig. 1). Animals produce the energy necessary for life via chemical reactions in which biomolecules (such as glucose) react with oxygen to release CO2, H2O, and energy. The metabolism is determined from the animal’s reported mass growth curve (the mass of the animal as a function of age during its juvenile growth) using a model based on conservation of energy. The metabolism reveals the rate at which oxygen is used by the animal. The efficiency of oxygen extraction is assumed to be the same as observed in modern birds (which have a very efficient “one-way” breathing modality and are direct descendants of dinosaurs). Using the estimated concentration of oxygen in Earth’s atmosphere during the Late Triassic period yields the amount of air that P. trossingensis breathed each minute. Finally, the tidal volume (the volume of air inhaled in each breath) was used to calculate its resting breathing rate. This exercise has been used in introductory and intermediate courses on thermal physics, and the students find it empowering (and fun) to be able to gain this insight into the physiology of a dinosaur.

Respiratory sinus arrhythmia magnitude quantification as a potential marker of stress and pain in cows and sheep.

Respiratory sinus arrhythmia (RSA) provides a quantitative evaluation of 'vagal tone' and may be used for pain and stress assessment in livestock. The aim was to quantify the magnitude of RSA in cows and sheep. In 7 cows and 4 sheep standing at rest we measured the 3-lead electrocardiogram (ECG) together with the pneumogram, to identify inspiration and expiration. For each breath, RSA was the difference in instantaneous heart rate (HR) between the inspiratory peak and the expiratory trough, in percent of mean HR. The resting breathing rates (28 ± 2 and 32 ± 5 breaths/min in cows and sheep, respectively) were about twice those expected for similar size non-ruminants, in conformity with previous reports. Both species had long-period (>15s) HR fluctuations. The average values of RSA, 1.4 ± 0.2% in cows and 7.8 ± 3.1 in sheep, were lower than those previously computed by an identical approach in humans (12%), dogs (40%) and horses (9%).In conclusion, by breath-by-breath analysis of instantaneous HR we measured RSA in both cows and sheep. Results from the present study represent a preliminary step in assessing whether or not RSA could be used as a biomarker for stress or pain in ruminants.

(253) Neural Moderators Supporting the Positive Relationship between Resting Breathing Rate and Pain Responses

Inter-individual differences in pain are shaped by a myriad of interactions between physiological, cognitive-affective and psychosocial factors. Interestingly, recent findings demonstrate that slow breathing-based manipulations reduce pain. Yet, it is unknown if non-manipulated, resting breathing rate predicts variability in behavioral and neural pain responses. The proposed study, part of a previously published dataset, examined if non-manipulated, slow breathing during noxious (heat = 49°C) and innocuous (neutral = 35°C) heat predicted lower pain. We postulated that subcortical respiration centers (brainstem) would moderate this hypothesized relationship. Seventy-four healthy, pain-free individuals were fitted with a respiratory transducer and administered two neutral and two heat series to the right calf during pseudo-continuous arterial spin labeling fMRI. After each fMRI series, participants provided pain intensity and unpleasantness ratings using a visual analog scale (0 = no pain – 10 = worst pain imaginable). Lower respiration rate was associated with lower pain intensity (r = .29, p = .01) and unpleasantness (r = .25, p = .03) ratings. Compared to innocuous stimulation, noxious heat produced significant activation in the bilateral thalamus, posterior/anterior insula, secondary somatosensory cortices (SII), primary somatosensory cortex (SI) corresponding to the stimulation site, and deactivation of the medial prefrontal (mPFC) and posterior cingulate cortex. Greater superior frontal gyrus and mPFC activation was associated with lower pain unpleasantness ratings. Two separate moderation analyses were conducted on respiration rate and pain intensity and unpleasantness, respectively. There were no significant neural moderators between pain intensity and respiration. High activation of the bilateral SI, contralateral SII, and ipsilateral superior parietal lobe moderated the positive relationship between respiration and pain unpleasantness. This study provides novel evidence that inter-individual differences in breathing predict pain responses and are moderated by brain mechanisms supporting the allocation of attention to intrinsic and extrinsic features of the pain experience.

Quantitative dynamic MRI (QdMRI) Volumetric Analysis of Pediatric Patients with Thoracic Insufficiency Syndrome.

The lack of standardizable objective diagnostic measurement techniques is a major hurdle in the assessment and treatment of pediatric patients with thoracic insufficiency syndrome (TIS). The aim of this paper is to explore quantitative dynamic MRI (QdMRI) volumetric parameters derived from thoracic dMRI in pediatric patients with TIS and the relationships between dMRI parameters and clinical measurements. 25 TIS patients treated with vertical expandable prosthetic titanium rib (VEPTR) surgery are included in this retrospective study. Left and right lungs at end-inspiration and end-expiration are segmented from constructed 4D dMRI images. Lung volumes and excursion (or tidal) volumes of the left/right chest wall and hemi-diaphragms are computed. Commonly used clinical parameters include thoracic and lumbar Cobb angles and respiratory measurements from pulmonary function testing (PFT). 200 3D lungs in total (left & right, pre-operative & post-operative, end-inspiration & end-expiration) are segmented for analysis. Our analysis indicates that change of resting breathing rate (RR) following surgery is negatively correlated with that of QdMRI parameters. Chest wall tidal volumes and hemi-diaphragm tidal volumes increase significantly following surgery. Clinical parameter RR reduced after surgical treatment with P values around 0.06 but no significant differences were found on other clinical parameters. The significant increase in post-operative tidal volumes suggests a treatment-related improvement in lung capacity. The reduction of RR following surgery shows that breathing function is improved. The QdMRI parameters may offer an objective marker set for studying TIS, which is currently lacking.

Astrocytes modulate brainstem respiratory rhythm-generating circuits and determine exercise capacity

Astrocytes are implicated in modulation of neuronal excitability and synaptic function, but it remains unknown if these glial cells can directly control activities of motor circuits to influence complex behaviors in vivo. This study focused on the vital respiratory rhythm-generating circuits of the preBötzinger complex (preBötC) and determined how compromised function of local astrocytes affects breathing in conscious experimental animals (rats). Vesicular release mechanisms in astrocytes were disrupted by virally driven expression of either the dominant-negative SNARE protein or light chain of tetanus toxin. We show that blockade of vesicular release in preBötC astrocytes reduces the resting breathing rate and frequency of periodic sighs, decreases rhythm variability, impairs respiratory responses to hypoxia and hypercapnia, and dramatically reduces the exercise capacity. These findings indicate that astrocytes modulate the activity of CNS circuits generating the respiratory rhythm, critically contribute to adaptive respiratory responses in conditions of increased metabolic demand and determine the exercise capacity.

Disorder of Renin‐Angiotensin System Promoting the Acute Pulmonary Inflammation by Particulate Matter 2.5 (PM2.5) Exposure

Acute or chronic particulate matter 2.5 (PM2.5) exposure can induce oxidative stress, inflammation and pulmonary impairment by traversing the blood‐air barrier of alveolar and then depositing at lung. In the present study, we tested whether the pulmonary inflammation and impairment induced by PM2.5 exposure are related to the disorder of pulmonary renin‐angiotensin system (RAS).In this study, we collected PM2.5 from waste gas which was produced from vehicle engine, and determined the component elements and structures of the PM2.5. The C57BL/6J (wild type, WT) mice and angiotensin converting enzyme II (ACE2) gene knockout (ACE2KO) mice were treated with the PM2.5 by intratracheal instillation once a day for a total of 3 days, and then sacrificed at the 4th day. Lung tissue of the mice was collected for the assays of molecular, biochemical and pathological changes to evaluate the acute pulmonary inflammation and lung injury induced by PM2.5 exposure.The results indicated that the most of collected particulates in this study were aggregated and parts of them formed structure of chains below 2.5 μm diameter. The major compositions of the PM2.5 are carbon and oxide, and contain little silicon, sulfate and copper. The body weight of both WT and ACE2 KO mice treated with PM2.5 was decreased and resting breathing rate was significantly increased. PM2.5 treatment induced pathological leukocyte infiltration in the lung, increased pulmonary immunocytokines concentration, including interleukin‐6 (IL‐6), tumor necrosis factor alpha (TNF‐α) and tumor growth factor beta 1 (TGF‐β1), and also promoted signaling protein ERK1/2 and STAT3 phosphorylation. The quantitative data showed that the levels of physiopathology and inflammation induced by PM2.5 were serious in the ACE2 KO mice compared with those in the WT mice. PM2.5 treatment significantly increased pulmonary ACE expression and activity in both WT and ACE2 KO mice. Interestingly, pulmonary ACE2 activity in the WT mice was also induced. We hypothesized that increased ACE2 activity in the WT mice is a physiological response for increased ACE activity due to PM2.5 exposure. However, the response is lack in the ACE2 KO mice because the mice being ACE2 deficiency. It is one of the reasons that serious physiopathology and inflammation induced by PM2.5 in the ACE2 KO mice compared with those in the WT mice.Our data reveals that acute inflammation and lung injury could be induced by PM2.5 treatment. The disorder of pulmonary RAS may aggravate the disease progressive of pulmonary system due to PM2.5 exposure. Therefore, we propose that it may be helpful for the cardiopulmonary patients by RAS regulation when the patients are exposed to severe particulate pollutants.

Simulation of the phase change and deposition of inhaled semi-volatile liquid droplets in the nasal passages of rats and humans

Inhaled airborne droplets may undergo phase change as they travel through the respiratory tract. Droplet evaporation and condensation depends on the physicochemical and thermodynamic properties of the aerosol and will impact deposition in the respiratory airways. The deposition behavior of four fragrance aerosols (d-limonene, linalool, benzaldehyde, and benzyl acetate) with different vapor pressures was simulated in anatomically accurate computational fluid dynamics (CFD) models of the rat and human nasal passages. Steady-state inspiratory airflow was simulated in each species at resting breathing rates. Droplet transport and deposition was simulated using Lagrangian particle tracking. Droplet size evolution due to phase change was governed by molecular diffusion to or from the droplet surface and was driven by the difference in partial pressures between the droplet surface and the surrounding environment. CFD predictions revealed significant evaporation of these fragrance materials in the nasal passages with evaporation rates dependent on the saturation vapor pressures of the substances. In the human nose, complete evaporation was observed for d-limonene droplets with initial diameters ≤6µm, benzaldehyde droplets ≤4µm, and benzyl acetate and linalool droplets <2µm. The minimum droplet size for complete evaporation was smaller in the rat nose due to higher deposition in the anterior nose. Larger droplets did not completely evaporate but decreased in size, thereby reducing deposition by inertial impaction in the nasal passages of each species. Quantification of droplet deposition in the nose has significant implications for lung dosimetry since vapor concentrations and droplet characteristics are altered during transport through the upper respiratory tract.

Numerical simulation of airflow and micro-particle deposition in human nasal airway pre- and post-virtual sphenoidotomy surgery.

In the present study, the effects of endoscopic sphenoidotomy surgery on the flow patterns and deposition of micro-particles in the human nasal airway and sphenoid sinus were investigated. A realistic model of a human nasal passage including nasal cavity and paranasal sinuses was constructed using a series of CT scan images of a healthy subject. Then, a virtual sphenoidotomy by endoscopic sinus surgery was performed in the left nasal passage and sphenoid sinus. Transient airflow patterns pre- and post-surgery during a full breathing cycle (inhalation and exhalation) were simulated numerically under cyclic flow condition. The Lagrangian approach was used for evaluating the transport and deposition of inhaled micro-particles. An unsteady particle tracking was performed for the inhalation phase of the breathing cycle for the case that particles were continuously entering into the nasal airway. The total deposition pattern and sphenoid deposition fraction of micro-particles were evaluated and compared for pre- and post-surgery cases. The presented results show that sphenoidotomy increased the airflow into the sphenoid sinus, which led to increased deposition of micro-particles in this region. Particles up to 25 μm were able to penetrate into the sphenoid in the post-operation case, and the highest deposition in the sphenoid for the resting breathing rate occurred for 10 μm particles at about 1.5%.

Regular slow-breathing exercise effects on blood pressure and breathing patterns at rest

Previous studies reported that a device-guided slow-breathing (DGB) exercise decreases resting blood pressure (BP) in hypertensive patients. This study investigated the effects of daily practice of DGB on (a) 24-h BP and breathing patterns in the natural environment, as well as (b) BP and breathing pattern during clinic rest. Altogether, 40 participants with pre-hypertension or stage 1 hypertension were trained to decrease breathing rate through DGB or to passively attend to breathing (control, CTL) during daily 15-min sessions. The participants practiced their breathing exercise at home for 4 weeks. The DGB (but not the CTL) intervention decreased clinic resting BP, mid-day ambulatory systolic BP (in women only) and resting breathing rate, and increased resting tidal volume. However, 24-h BP level was not changed by DGB or CTL interventions, nor was overnight breathing pattern. These findings are consistent with the conclusion that a short-term, autonomic mechanism mediated the observed changes in resting BP, but provided no evidence that regular DGB affected factors involved in long-term BP regulation. Additional research will be needed to determine whether 24-h BP can be lowered by a more prolonged intervention.

The effect of feeding on the respiratory activity of the sloth.

The aim of the present study was to confirm whether feeding influences the resting breathing rate and to observe possible alterations in blood gas and pH levels produced by feeding in unanesthetized sloths (Bradypus variegatus). Five adult male sloths (4.1 +/- 0.6 kg) were placed daily in an experimental chair for a period of at least 4 h for sitting adaptation. Five measurements were made for each sloth. However, the sloths one, two and five were studied once and the sloths three and four were studied twice. Breathing rate was determined with an impedance meter and the output signal was digitized. Arterial blood samples were collected for blood gas analysis with a BGE electrolytes analyzer and adjusted for the animal's body temperature and hemoglobin content. The data are reported as mean +/- SD and were collected during the resting period (8:00-10:00 h) and during the feeding period (16:00-18:00 h). The mean breathing rate increased during mastication of ymbahuba leaves (rest: 5.0 +/- 1, feeding: 10 +/- 1 bpm). No significant alterations were observed in arterial pH (rest: 7.42 +/- 0.05, feeding: 7.45 +/- 0.03), PCO2 (rest: 35.2 +/- 5.3, feeding: 33.3 +/- 4.4 mmHg) or PO2 (rest: 77.5 +/- 8.2, feeding: 78.4 +/- 5.2 mmHg) levels. These results indicate that in unanesthetized sloths 1) feeding evokes an increase in breathing rate without a significant change in arterial pH, PCO2 or PO2 levels, and 2) the increase in breathing rate produced by feeding probably is due to the act of mastication.

Numerical simulation of airflow in the human nasal cavity.

An anatomically correct finite element mesh of the right human nasal cavity was constructed from CAT scans of a healthy adult nose. The steady-state Navier-Stokes and continuity equations were solved numerically to determine the laminar airflow patterns in the nasal cavity at quiet breathing flow rates. In the main nasal passages, the highest inspiratory air speed occurred along the nasal floor (below the inferior turbinate), and a second lower peak occurred in the middle of the airway (between the inferior and middle turbinates and the septum). Nearly 30 percent of the inspired volumetric flow passed below the inferior turbinate and about 10 percent passed through the olfactory airway. Secondary flows were induced by curvature and rapid changes in cross-sectional area of the airways, but the secondary velocities were small in comparison with the axial velocity through most of the main nasal passages. The flow patterns changed very little as total half-nasal flow rate varied between resting breathing rates of 125 m/s and 200 ml/s. During expiration, the peaks in velocity were smaller than inspiration, and the flow was more uniform in the turbinate region. Inspiratory streamline patterns in the model were determined by introducing neutrally buoyant point particles at various locations on the external naris plane, and tracking their path based on the computed flow field. Only the stream from the ventral tip of the naris reached the olfactory airway. The numerically computed velocity field was compared with the experimentally measured velocity field in a large scale (20x) physical model, which was built by scaling up from the same CAT scans. The numerical results showed good agreement with the experimental measurements at different locations in the airways, and confirmed that at resting breathing flow rates, airflow through the nasal cavity is laminar.

Cold dry air-induced rhinitis: effect of inhalation and exhalation through the nose

Ten subjects with a history of cold air-induced nasal symptoms participated in a randomized two-period crossover study to evaluate the occurrence and magnitude of the reaction induced by inhalation and exhalation of cold dry air through the nose. The protocol involved breathing of either warm moist or cold dry air for 45 min at resting breathing rates. The nasal response was quantified by determining the amount of produced secretions as well as by measuring histamine and N-alpha-p-tosyl-L-arginine methyl (TAME) esterase activities in recovered nasal lavage fluids. Symptom scores were obtained. Warm moist air did not increase symptoms nor did it result in any significant changes in secretions or mediator levels. Compared with baseline, cold dry air induced significant rhinorrhea and increased both secretion weights (9.6 +/- 1.3 vs. 28.1 +/- 6.5 mg; P = 0.01) and the levels of histamine (3.9 +/- 1.2 vs. 10.6 +/- 2.7 ng/ml; P = 0.02) and TAME esterase activity (3.1 +/- 0.8 vs. 7.0 +/- 2.0 counts.min-1.10(-3); P = 0.01). We conclude that bidirectional nasal breathing of cold dry air results in a reaction that is qualitatively similar to that induced when air is only inhaled through the nose and exhaled through the mouth.

Inhalability of Large Particles into the Human Nasal Passage: In Vivo Studies in Still Air

The aspiration of large particles (18–30.5 μm) in the human nose was studied to determine the inhalation efficiency as a function of particle size, and to evaluate the upper size cutoff for inhalable particles in still air. Under these conditions, the ability of a particle to be inhaled is dependent on the inhalation velocity entering the nose and the particle terminal settling velocity. Nasal inhalation of radiolabeled pollen and wood dust aerosols was measured in four subjects at normal resting breathing rates. The efficiency of nasal aspiration was found to decrease as the square of the particle size. The upper size cutoff for inhalability was estimated to be approximately 39 μm in still air.

Repair but Not Potentiation Observed in Mouse Lung Irradiated with Neon Ions

The lungs of mice were irradiated with 1, 4, or 7 fractions of X rays or neon ions in a 4-cm spread Bragg peak. Lung function as a function of total radiation dose was tested at 7 and 12 months after irradiation by measuring the resting breathing rate in a whole-body plethysmograph. The isoeffect doses increased sequentially with X rays for 1 through 4 to 7 fractions, demonstrating repair of sublethal radiation injury as previously reported. There was also a significant increase of isoeffect dose with neon ions between 1 and 4 fractions but no further increase at 7 fractions. Thus repair instead of potentiation of radiation injury in lung clearly occurred after neon ion irradiation. The effectiveness of neon ions appeared to be closer to that of neutrons with a mean energy of 8 meV than those with a mean energy of 2.3 meV.

Apneic diffusion oxygenation and continuous flow apneic ventilation. A review.

Evolution of life coincides with the most rapid rate of rise in atmospheric oxygen concentration during Devonian time. Oxygen is essential for life, but at the same time is a cellular poison if present in tensions considerably higher than those the particular cellular milieu has become adapted to. Animals exposed to low oxygen tensions breathe continuously, e.g. most species of fish obtain their oxygen from a continuous flow of water at low oxygen tensions. Evolution from water to land breathing generally is associated with intermittent breathing, mass movement of gas in one direction, i.e. inhalation and exhalation. Intermittent breathing is part of this evolutionary process and reduces the inspired oxygen tension from 150 mmHg (19.95 kPa) to approximately 100 mmHg (13.3 kPa) at the alveolar blood interface. Perhaps evolution from continuous ventilation to intermittent breathing may be protecting the body against the high atmospheric oxygen tension. Therefore, it is not surprising that mammals can have adequate oxygen uptake with apneic diffusion oxygenation (ADO) and continuous flow apneic ventilation (CFAV). Mechanical ventilation classic techniques, i.e. intermittent positive-pressure ventilation and continuous positive-pressure ventilation, employ ventilatory frequencies close to the resting breathing rate of the adult. Utilizing low-compression patient circuits has made mechanical ventilation with higher frequencies possible. 60 to 400 breaths per min is used for high-frequency positive-pressure ventilation and high-frequency jet ventilation, and up to 40 Hz is used for high-frequency oscillation (HFO). The two extremes of artificial ventilation - ADO, i.e. supply of O2 by continuous flow, and HFO, i.e. supply of O2 by oscillatory changes - both primarily involve diffusion, even though convection (also secondary to cardiac oscillations) obviously is important in the process of gas exchange. Some recent experimental findings favor continued development and evaluation of CFAV as an additional alternative to artificial ventilation.

Diminished hypercapnic drive in endogenous or severe depression

Resting breathing rate, resting end-tidal PCO 2 and ventilatory response to CO 2 were studied in patients with primary depression. Patients tended to breathe faster and showed decreased PECO 2 levels when compared with control subjects. Carbon dioxide response was determined using a modification of the rebreathing technique of Read. Endogenous depressives, unlike reactive depressives, tended to give low CO 2 responses and low CO 2 thresholds. Carbon dioxide responses of patients on admission correlated highly with severity of depression. The modification of the standard rebreathing technique, and the relationship between CO 2 response and physical and psychological variables are discussed.