Differences In Breathing Pattern Research Articles

The activity of suprahyoid muscles during sevoflurane-induced gasping in mice

Sevoflurane-induced gasping in mice involves an enormous increase in inspiratory effort, mandibular movement, and a marked decrease in respiratory frequency (fR). We examined differences in breathing patterns and electromyogram activity (EMGSH) of the suprahyoid muscles (SHMs) during eupnea under 3.2 % (1 MAC: minimum alveolar concentration) sevoflurane inhalation and sevoflurane-induced gasping under 6.5 % (2 MAC) sevoflurane inhalation in eight spontaneously breathing, tracheally intubated, adult mice. We found that the phasic EMGSH is obtained only during inspiration in eupnea and gasping and that integrated EMGSH increases more, as a percent of baseline (% baseline) than tidal volume (VT) during gasping (median [interquartile range]; integrated EMGSH: 720 [425–1965] vs. VT: 300 [238–373], P < 0.05). We also found that the onset of EMGSH precedes the start of airflow while maintaining a bell-shaped EMGSH contour, which characterizes the EMG of upper airway dilator (UAD) muscles during eupnea and gasping. Vigorous respiratory-related mandibular movements were never observed during eupnea but were observed in seven of 8 mice during sevoflurane-induced gasping. Our observations indicate that SHMs act as a preferentially activating UAD muscle, contributing to the development of mandibular respiratory movements.

Breathing Pattern Response after 6 Weeks of Inspiratory Muscle Training during Exercise.

(1) Background: The breathing pattern is defined as the relationship between the tidal volume (VT) and breathing frequency (BF) for a given VE. The aim of this study was to evaluate whether inspiratory muscle training influenced the response of the breathing pattern during an incremental effort in amateur cyclists. (2) Methods: Eighteen amateur cyclists completed an incremental test to exhaustion, and a gas analysis on a cycle ergometer and spirometry were conducted. Cyclists were randomly assigned to two groups (IMTG = 9; CON = 9). The IMTG completed 6 weeks of inspiratory muscle training (IMT) using a PowerBreathe K3® device at 50% of the maximum inspiratory pressure (Pimax). The workload was adjusted weekly. The CON did not carry out any inspiratory training during the experimental period. After the 6-week intervention, the cyclists repeated the incremental exercise test, and the gas analysis and spirometry were conducted. The response of the breathing pattern was evaluated during the incremental exercise test. (3) Results: The Pimax increased in the IMTG (p < 0.05; d = 3.1; +19.62%). Variables related to the breathing pattern response showed no differences between groups after the intervention (EXPvsCON; p > 0.05). Likewise, no differences in breathing pattern were found in the IMTG after training (PREvsPOST; p > 0.05). (4) Conclusions: IMT improved the strength of inspiratory muscles and sport performance in amateur cyclists. These changes were not attributed to alterations in the response of the breathing pattern.

Physiological responses to treadmill exercise in size- and fitness-matched male and female firefighter applicants

Physiological responses during a standardised treadmill test for structural firefighting employment were compared in 41 pairs of size-matched, male and female applicants. Applicants wore personal exercise clothing, running shoes, and fire protective ensemble with self-contained breathing apparatus (added mass 21.2 ± 1.0 kg). Applicants walked at 1.56 m·s−1, completing a 5-min warm-up, 8-min at 10% grade, and then, progressive 1-min stages to exhaustion. The cut-score required completion of 13-min of exercise. Up to the cut-score, no differences in heart rate, oxygen uptake or minute ventilation were detected between sexes. At time 12:30–13:00 min, V̇O2 was 45.7 ± 0.6 vs. 44.2 ± 0.5 mL·kg−1·min−1 (body mass) for males and females, respectively. Despite similar physiological responses at minute 13, females worked at higher fractions of peak than males (p < 0.05). A second analysis compared a subset of 27 fitness-matched (V̇O2peak) male-female pairs. Fitness-matching further reduced or eliminated most observed differences in physiological responses, except small differences in breathing pattern. Practitioner Summary: Physiological responses during a standardised treadmill test for firefighter applicants were investigated in male and female applicants matched on size and fitness. Absolute responses to exercise were the same for both sexes when size-matched, but relative intensity was higher for females. Fitness-matching reduced or eliminated most previously observed differences. Abbreviations: NFPA: National Fire Protection Association; V̇O2: rate of oxygen consumption; V̇O2 peak: rate of oxygen consumption at peak exercise; PAR-Q+: Physical Activity Readiness Questionnaire Plus; SCBA: self-contained breathing apparatus; ANOVA: analysis of variance; V̇E: minute ventilation; V̇ Epeak: minute ventilation at peak exercise; V̇ E/V̇O2: ventilatory equivalent for oxygen.

The Effect Of Sex On The Mechanical Cost And Work Of Breathing During Exercise

Sex differences in pulmonary system structure and function lead to differences in respiratory mechanics during exercise. Specifically, women incur a greater power of breathing (Pb) during exercise than men. However, women typically display a more rapid breathing pattern at a given minute ventilation during exercise and, as such, it remains unclear whether previously reported sex differences in Pb are due to higher respiratory frequencies (i.e., more breaths per minute), or if the work of breathing (Wb) is indeed greater per breath in women compared with men. Moreover, it remains unclear whether differences exist between sexes when the Wb during exercise is converted to a mechanical cost of breathing (i.e., J·L-1). PURPOSE: To examine differences in the Wb (J·breath-1) and the mechanical cost of breathing (J·L-1) between men and women during incremental cycling. METHODS: Forty-two healthy participants (29 ± 15 yrs) completed a graded exercise test on a cycle ergometer. During the test, participants were instrumented with an esophageal balloon catheter to measure esophageal pressure as a surrogate of pleural pressure. Chest wall compliance was measured at rest before exercise via the two-point method. The Wb was determined via the modified Campbell diagram. The mechanical cost was computed as Wb divided by tidal volume. To compare the Wb (and components) and the mechanical cost between sexes we used a generalized additive mixed model (GAMM) approach. Values are reported as the mean and 95% confidence interval. RESULTS: The total Wb was greater in men than women at ventilations >140 L·min-1 (men = 12.9 J·breath-1 [11.8, 14.1]; women = 11.4 J·breath-1 [10.2, 12.5]; p < 0.05). The mechanical cost of breathing was greater in women at ventilations >95 L·min-1 (men = 2.7 J·L-1 [2.3, 3.2]; women = 3.4 J·L-1 [2.9, 3.8]; p < 0.05). CONCLUSIONS: Wb (J·breath-1) is effectively no different between sexes across all ventilations attained by the women in our study (up to 120 L·min-1). Even when tidal volume is taken into consideration, the mechanical cost of breathing is not greater in women until high ventilations suggesting that differences in the Pb are due to sex differences in breathing pattern rather than differences in the mechanical cost of breathing.

Effects of non-invasive respiratory supports on inspiratory effort in moderate-severe COVID-19 patients. A randomized physiological study

Rationale and objectiveVarious forms of Non-invasive respiratory support (NRS) have been used during COVID-19, to treat Hypoxemic Acute Respiratory Failure (HARF), but it has been suggested that the occurrence of strenuous inspiratory efforts may cause Self Induced Lung Injury(P-SILI). The aim of this investigation was to record esophageal pressure, when starting NRS application, so as to better understand the potential risk of the patients in terms of P-SILI and ventilator induced lung injury (VILI). Methods and measurements21 patients with early de-novo respiratory failure due to COVID-19, underwent three 30 min trials applied in random order: high-flow nasal cannula (HFNC), continuous positive airway pressure (CPAP), and non-invasive ventilation (NIV). After each trial, standard oxygen therapy was reinstituted using a Venturi mask (VM). 15 patients accepted a nasogastric tube placement. Esophageal Pressure (ΔPes) and dynamic transpulmonary driving pressure (ΔPLDyn), together with the breathing pattern using a bioelectrical impedance monitor were recorded. Arterial blood gases were collected in all patients. Main resultsNo statistically significant differences in breathing pattern and PaCO2 were found. PaO2/FiO2 ratio improved significantly during NIV and CPAP vs VM. NIV was the only NRS to reduce significantly ΔPes vs. VM (-10,2 ±5 cmH20 vs -3,9 ±3,4). No differences were found in ΔPLDyn between NRS (10,2±5; 9,9±3,8; 7,6±4,3; 8,8±3,6 during VM, HFNC, CPAP and NIV respectively). Minute ventilation (Ve) was directly dependent on the patient's inspiratory effort, irrespective of the NRS applied. 14% of patients were intubated, none of them showing a reduction in ΔPes during NRS. ConclusionsIn the early phase of HARF due to COVID-19, the inspiratory effort may not be markedly elevated and the application of NIV and CPAP ameliorates oxygenation vs VM. NIV was superior in reducing ΔPes, maintaining ΔPLDyn within a range of potential safety.

Obesity, tidal volume, and pulmonary deposition of fine particulate matter in children with asthma.

Obese children with asthma are more vulnerable to air pollution, especially fine particulate matter (PM2.5), but reasons are poorly understood. We hypothesised that differences in breathing patterns (tidal volume, respiratory rate and minute ventilation) due to elevated body mass index (BMI) may contribute to this finding. To investigate the association of BMI with breathing patterns and deposition of inhaled PM2.5. Baseline data from a prospective study of children with asthma were analysed (n=174). Tidal breathing was measured by a pitot-tube flowmeter, from which tidal volume, respiratory rate and minute ventilation were obtained. The association of BMI z-score with breathing patterns was estimated in a multivariable model adjusted for age, height, race, sex and asthma severity. A particle dosimetry model simulated PM2.5 lung deposition based on BMI-associated changes in breathing patterns. Higher BMI was associated with higher tidal volume (adjusted mean difference (aMD) between obese and normal-range BMI of 25 mL, 95% CI 5-45 mL) and minute ventilation (aMD 453 mL·min-1, 95% CI 123-784 mL·min-1). Higher tidal volumes caused higher fractional deposition of PM2.5 in the lung, driven by greater alveolar deposition. This translated into obese participants having greater per-breath retention of inhaled PM2.5 (aMD in alveolar deposition fraction of 3.4%, 95% CI 1.3-5.5%), leading to worse PM2.5 deposition rates. Obese children with asthma breathe at higher tidal volumes that may increase the efficiency of PM2.5 deposition in the lung. This finding may partially explain why obese children with asthma exhibit greater sensitivity to air pollution.

Unilateral diaphragmatic paralysis: inspiratory muscles, breathlessness and exercise capacity.

BackgroundPatients with unilateral diaphragmatic paralysis (UDP) may present with dyspnoea without specific cause and limited ability to exercise. We aimed to investigate the diaphragm contraction mechanisms and nondiaphragmatic inspiratory muscle activation during exercise in patients with UDP, compared with healthy individuals.MethodsPulmonary function, as well as volitional and nonvolitional inspiratory muscle strength were evaluated in 35 patients and in 20 healthy subjects. Respiratory pressures and electromyography of scalene and sternocleidomastoid muscles were continuously recorded during incremental maximal cardiopulmonary exercise testing until symptom limitation. Dyspnoea was assessed at rest, every 2 min during exercise and at the end of exercise with a modified Borg scale.Main resultsInspiratory muscle strength measurements were significantly lower for patients in comparison to controls (all p<0.05). Patients achieved lower peak of exercise (lower oxygen consumption) compared to controls, with both gastric (−9.8±4.6 cmH2O versus 8.9±6.0 cmH2O) and transdiaphragmatic (6.5±5.5 cmH2O versus 26.9±10.9 cmH2O) pressures significantly lower, along with larger activation of both scalene (40±22% EMGmax versus 18±14% EMGmax) and sternocleidomastoid (34±22% EMGmax versus 14±8% EMGmax). In addition, the paralysis group presented significant differences in breathing pattern during exercise (lower tidal volume and higher respiratory rate) with more dyspnoea symptoms compared to the control group.ConclusionThe paralysis group presented with exercise limitation accompanied by impairment in transdiaphragmatic pressure generation and larger accessory inspiratory muscles activation compared to controls, thereby contributing to a neuromechanical dissociation and increased dyspnoea perception.

Differences in the point of optimal ventilatory efficiency and the anaerobic threshold in untrained adults aged 50 to 60 years

BackgroundThe point of optimal ventilatory efficiency (POE) and the anaerobic threshold (AT) are traditionally considered the same ventilatory indices, but recently differences between them have been reported. Therefore, the aim of this study was to identify different response patterns regarding POE and AT, and to analyse differences in breathing patterns as a possible explanation. Methods118 females and 199 males aged 50 to 60 years performed an exercise test with gas analysis. POE and AT were determined, and the breathing patterns concerning ventilation, breathing frequency and tidal volume were assessed. Results and ConclusionOur study identified two different response patterns concerning the ventilatory indices POE and AT. Participants with a work rate difference between POE and AT (82% of all participants) were not different regarding breathing patterns of breathing frequency and tidal volume. However, the difference in work rate was explained by an early increase in ventilation and a higher aerobic capacity.

The effect of inert gas choice on multiple breath washout in healthy infants: differences in lung function outcomes and breathing pattern.

The detrimental effects on breathing pattern during multiple breath inert gas washout (MBW) have been described with different inhaled gases [100% oxygen (O2) and sulfur hexafluoride (SF6)] but detailed comparisons are lacking. N2- and SF6-based tests were performed during spontaneous quiet sleep in 10 healthy infants aged 0.7-1.3 yr using identical hardware. Differences in breathing pattern pre and post 100% O2 and 4% SF6 exposure were investigated, and the results obtained were compared [functional residual capacity (FRC) and lung clearance index (LCI)]. During 100% O2 exposure. mean inspiratory flow ("respiratory drive") decreased transiently by mean (SD) 28 (9)% ( P < 0.001), and end-tidal CO2 (carbon dioxide) increased by mean (SD) 0.3 (0.4)% units ( P < 0.05) vs. air breathing prephase. During subsequent N2 washin (i.e., recovery phase), the pattern of change reversed. No significant effect on breathing pattern was observed during SF6 testing. In vitro testing confirmed that technical artifacts did not explain these changes. Mean (SD) FRC and LCI in vivo were significantly higher with N2 vs. SF6 washout: 216 (33) vs. 186 (22) ml ( P < 0.001) and 8.25 (0.85) vs. 7.55 (0.57) turnovers ( P = 0.021). Based on these results, SF6 based MBW is the preferred methodology for tests in this age range. NEW & NOTEWORTHY Inert gas choice for multiple breath inert gas washout (MBW) in infants has important consequences on both breathing pattern during test performance and the functional residual capacity and lung clearance index values obtained. Data suggest the detrimental effect of breathing pattern of 100% O2 and movement of O2 across the alveolar capillary membrane, with direct effects on MBW outcomes. SF6 MBW during infancy avoids this and can be further optimized by addressing the sources of technical artifact identified in this work.

Uphill Cycling: Seated versus Standing Economy and Heart Rate

Introduction Elite cyclists differentiate between seated and standing pedaling techniques while climbing. There has been debate as to which technique is the most economical for cyclists riding a sustained climb, and what the benefits and drawbacks of the two techniques are. The purpose of this study was to compare economy (VO 2 ) and heart rate (HR) for seated and standing cycling positions when riding uphill at constant speed and grade.  Methods Three male collegiate team cyclists (21.3 ± 1.7 yrs; 68.0 ± 4.6 kg) participated in a pilot study of a single continuous bout of uphill riding which used both seated and standing positions. Cycling was at subthreshold intensity with fixed speed (8 mph; 3.58 m/s) and grade (8%) on a large treadmill (length 3 m). After a 10-minute warmup, a 20-minute trial began which randomly alternated 5-minute stages of either seated or standing cycling. Specific gears generating cadences of approximately 66 and 60 rpm (seated and standing respectively) were required during each 5-minute stage. VO2 and HR data were collected continuously throughout the test but the last two minutes of each stage were compared using single-subject analyses. VO2 data were averaged every 15 seconds using a Parvo Medics metabolic cart; HR was recorded at 1 s intervals using a Garmin Edge 800 and chest strap and Rating of Perceived Exertion (RPE) was determined at the end of each 5 minute stage. Results Each rider required greater oxygen uptake and had higher heart rates when standing compared to seated (p < .05). Mean VO2 values were 3.06 ± 0.37 L/min and 3.17± 0.43 L/min whereas mean HR values were 166 ± 5 bpm and 175 ± 4 bpm for seated and standing trials, respectively (Figure 1 & 2). RPE was less consistent; two riders increased RPE while standing, while one increased RPE when seated.  Discussion Clear differences in VO 2 and heart rate were observed between the two cycling techniques. Two of the subjects began the trial in a standing position while one subject began seated. When VO 2 was compared across all three subjects, a higher metabolic cost for a standing vs. seated position was found. This could be due to factors such as slight differences in breathing patterns between the two positions, muscle recruitment shifts, as well as angular changes to the rider’s body while moving back and forth in the standing position. The differences in heart rate, which were about 5% higher for standing vs. seated cycling, followed the increase in physiological demands while standing. Cardiovascular drift was observed during the 20 minutes of climbing with increases of both HR and VO 2 from first to second stage of the standing or seated periods. This complicated direct comparison of a 5 minute stage mean VO 2 or HR with the stage immediately afterward as these would be about 3 to 5% higher simply due to cardiac drift. Second bout comparisons (minutes 10-15 and 15-20) provided the clearest results with distinct decrease of VO 2 and HR from standing to seated in the last 10 minutes despite the upward cardiovascular drift.  Conclusions In a real world scenario, muscle fatigue, pedaling technique and air drag forces may also impact a cyclist’s decision to ride seated or standing. However, our research showed that elite cyclists required greater oxygen uptake and have higher heart rates when climbing in a standing position compared to seated.

Sex differences in the intensity and qualitative dimensions of exertional dyspnea in physically active young adults.

Understanding sex differences in the qualitative dimensions of exertional dyspnea may provide insight into why women are more affected by this symptom than men. This study explored the evolution of the qualitative dimensions of dyspnea in 70 healthy, young, physically active adults (35 M and 35 F). Participants rated the intensity of their breathing discomfort (Borg 0-10 scale) and selected phrases that best described their breathing from a standardized list (work/effort, unsatisfied inspiration, and unsatisfied expiration) throughout each stage of a symptom-limited incremental-cycle exercise test. Following exercise, participants selected phrases that described their breathing at maximal exercise from a list of 15 standardized phrases. Intensity of breathing discomfort was significantly higher in women for a given ventilation, but differences disappeared when ventilation was expressed as a percentage of maximum voluntary ventilation. The dominant qualitative descriptor in both sexes throughout exercise was increased work/effort of breathing. At peak exercise, women were significantly more likely to select the following phrases: "my breathing feels shallow," "I cannot get enough air in," "I cannot take a deep breath in," and "my breath does not go in all the way." Women adopted a more rapid and shallow breathing pattern and had significantly higher end-inspiratory lung volumes relative to total lung capacity throughout exercise relative to men. These findings suggest that men and women do not differ in their perceived quality of dyspnea during submaximal exercise, but subjective differences appear at maximal exercise and may be related, at least in part, to underlying sex differences in breathing patterns and operating lung volumes during exercise.

Very Preterm Infants Failing CPAP Show Signs of Fatigue Immediately after Birth.

ObjectiveTo investigate the differences in breathing pattern and effort in infants at birth who failed or succeeded on continuous positive airway pressure (CPAP) during the first 48 hours after birth.MethodsRespiratory function recordings of 32 preterm infants were reviewed of which 15 infants with a gestational age of 28.6 (0.7) weeks failed CPAP and 17 infants with a GA of 30.1 (0.4) weeks did not fail CPAP. Frequency, duration and tidal volumes (VT) of expiratory holds (EHs), peak inspiratory flows, CPAP-level and FiO2-levels were analysed.ResultsEH incidence increased <6 minutes after birth and remained stable thereafter. EH peak inspiratory flows and VT were similar between CPAP-fail and CPAP-success infants. At 9-12 minutes, CPAP-fail infants more frequently used smaller VTs, 0-9 ml/kg and required higher peak inspiratory flows. However, CPAP-success infants often used large VTs (>9 ml/kg) with higher peak inspiratory flows than CPAP-fail infants (71.8 ± 15.8 vs. 15.5 ± 5.2 ml/kg.s, p <0.05). CPAP-fail infants required higher FiO2 (0.31 ± 0.03 vs. 0.21 ± 0.01), higher CPAP pressures (6.62 ± 0.3 vs. 5.67 ± 0.26 cmH2O) and more positive pressure-delivered breaths (45 ± 12 vs. 19 ± 9%) (p <0.05)ConclusionAt 9-12 minutes after birth, CPAP-fail infants more commonly used lower VTs and required higher peak inspiratory flow rates while receiving greater respiratory support. VT was less variable and larger VT was infrequently used reflecting early signs of fatigue.

An iterative approach to respiratory self-navigated whole-heart coronary MRA significantly improves image quality in a preliminary patient study.

In respiratory self-navigated coronary MRA, the selection of a reference position may have a direct effect on image quality. While end-expiration is commonly used as reference, it may be ill defined in cases of irregular breathing. Here, an iterative self-navigation approach that operates without a reference position was implemented and tested in healthy volunteers and patients. Data were acquired in 15 healthy volunteers and in 23 patients. Images obtained with end-expiratory self-navigation were compared with those obtained with the iterative approach that incorporates cross-correlation to iteratively minimize a global measure of respiratory displacement. Vessel sharpness, length, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were evaluated while differences in breathing patterns between the two sub-groups were assessed, too. Vessel sharpness and length were similar for both methods in healthy volunteers. In patients, a significant improvement in vessel sharpness and length was obtained using the iterative approach. SNR and CNR remained constant. While end-expiration was the most frequent respiratory phase in healthy volunteers (57.6 ± 16.2%), intermediate respiratory phases (43.4 ± 30.1%) were predominantly found in patients. An iterative approach to respiratory motion correction in self-navigation may lead to significant improvements in coronary MRA image quality in patients with a less consistent end-expiratory respiratory phase.

Ventilatory response to exercise in adolescents with cystic fibrosis and mild-to-moderate airway obstruction.

Data regarding the ventilatory response to exercise in adolescents with mild-to-moderate cystic fibrosis (CF) are equivocal. This study aimed to describe the ventilatory response during a progressive cardiopulmonary exercise test (CPET) up to maximal exertion, as well as to assess the adequacy of the ventilatory response for carbon dioxide (CO2) exhalation. Twenty-two adolescents with CF (12 boys and 10 girls; mean ± SD age: 14.3 ± 1.3 years; FEV1: 78.6 ± 17.3% of predicted) performed a maximal CPET. For each patient, data of a sex- and age matched healthy control was included (12 boys and 10 girls; mean ± SD age: 14.3 ± 1.4 years). At different relative exercise intensities of 25%, 50%, 75%, and 100% of peak oxygen uptake (VO2peak), breathing pattern, estimated ventilatory dead space ventilation (VD/VT ratio), minute ventilation (VE) to CO2 production relationship (VE/VCO2-slope), partial end-tidal CO2 tension (PETCO2), and the VE to the work rate (VE/WR) ratio were examined. VO2peak was significantly reduced in CF patients (P = 0.01). We found no differences in breathing pattern between both groups, except for a significantly higher VE at rest and a trend towards a lower VE at peak exercise in patients with CF. Significantly higher values were found for the estimated VD/VT ratio throughout the CPET in CF patients (P < 0.01). VE/VCO2-slope and PETCO2 values differed not between the two groups throughout the CPET. VE/WR ratio values were significantly higher in CF during the entire range of the CPET (P < 0.01). This study found an exaggerated ventilatory response (high VE/WR ratio values), which was adequate for CO2 exhalation (normal VE/VCO2-slope and PETCO2 values) during progressive exercise up to maximal exhaustion in CF patients with mild-to-moderate airway obstruction.

Comparison of respiratory function during TIVA and isoflurane anaesthesia in ponies Part II: breathing patterns and transdiaphragmatic pressure

ObjectiveTo compare breathing patterns and transdiaphragmatic pressure during total intravenous (TIVA) and isoflurane anaesthesia in ponies. Study designExperimental, cross–over study. AnimalsSix healthy ponies weighing 286 (233–388) ± 61 kg, age 13 (9–16) ± 3 years. MethodsFollowing premedication with romifidine [80 μg kg−1 intravenously (IV)], general anaesthesia was induced with midazolam (0.06 mg kg−1 IV) and ketamine (2.5 mg kg−1 IV) and maintained with either isoflurane (Fe’Iso = 1.1%) (T-ISO) or an IV combination of romifidine (120 μg kg−1 per hour), midazolam (0.09 mg kg−1 hour−1) and ketamine (3.3 mg kg−1 hour−1) (T-TIVA), while breathing 60% oxygen (FIO2). The circumference changes of the rib cage (RC) and abdominal compartment (ABD) were recorded using respiratory ultrasonic plethysmography (RUP). Balloon tipped catheters were placed in the distal oesophagus and the stomach and maximal transdiaphragmatic pressure (Pdi max) was calculated during Mueller's manoeuvre. ResultsThe breathing pattern T-ISO was more regular and respiratory rate significantly lower compared with T-TIVA. Ponies in T-TIVA showed regularly appearing sighs, which were never observed in T-ISO. Different contribution of the RC and ABD compartments to the breathing pattern was observed with a smaller participation of the RC to the total volume change during T-ISO. Transdiaphragmatic pressures (mean 13.7 ± SD 8.61 versus 23.4 ± 7.27 cmH2O, p < 0.0001) were higher in T-TIVA compared to T-ISO. The sum of the RC and ABD circumferential changes was lower during T-TIVA compared to T-ISO (6.32 ± 4.42 versus 11.72 ± 4.38 units, p < 0.0001). Conclusion and clinical relevanceMarked differences in breathing pattern and transdiaphragmatic pressure exist during inhalation- and TIVA and these should be taken into account for clinical estimation of anaesthetic depth.

Effects of feedback on the perception of inspiratory resistance in children with persistent asthma: a signal detection approach.

Accurate perception of asthma episodes increases the likelihood that they will be managed effectively. The purpose of the study was to examine the effect of feedback in a signal detection task on perception of increased airflow obstruction in children with persistent asthma. The effect of feedback training on the perception of resistive loads was evaluated in 155 children with persistent asthma between 8 and 15 years of age. Each child participated in four experimental sessions that occurred approximately once every 2 weeks, an initial session followed by three training sessions. During the initial session, the threshold resistance to breathing was determined for each child. Subsequently, each child was randomly assigned to one of two resistive load training conditions in a signal detection paradigm: training with immediate performance feedback or training with no performance feedback. The threshold resistance to breathing, determined in the initial session, was equivalent between groups. Children in the feedback condition discriminated more accurately between both the presence and the absence of increases in the resistance to breathing (206 [48] versus 180 [39] correct responses, p < .001), and differences over time between groups increased reliably as a function of training (165 [40] versus 145 [32] correct responses, p < .001). Response times and confidence ratings were equivalent between groups, and no differences in breathing patterns were observed between conditions. Feedback training results in improved perception of respiratory sensations in children with asthma, a finding with implications for strategies of asthma self-management.

Inter-individual differences in breathing pattern at high levels of incremental cycling exercise in healthy subjects

Interindividual differences in the rate of changes in tidal volume (VT) and respiratory frequency (fR) were examined during a maximal incremental cycling exercise. The gain of the inspiratory off-switch reflex was inferred from the VT vs. inspiratory duration (Ti) relationship. Some subjects also executed a static handgrip exercise, used as a “non-dynamic” exercise trial to study patterning of breathing.Above the ventilatory threshold (VTh), two patterns of response were identified: in group 1, the rate of change in VT significantly increased, while in group 2 the breakpoint of ventilation solely resulted from fR increase. After the respiratory compensation point, a tachypnoeic response always occurred. A leftward shift of the VT vs. Ti relationship, i.e., an inspiratory off-switch reflex, was measured during the handgrip in group 2 subjects as well as marked fR variations.Our study identifies two different patterns of breathing after the VTh. The subjects who present a tachypnoeic response to exercise above the VTh have a higher sensitivity to pulmonary inflation and their tachypnoeic response was ubiquitous during a maximal handgrip test.

Telemetric analysis of breathing pattern variability in recurrent airway obstruction (heaves)-affeeted horses

To use noninvasive respiratory inductance plethysmography (RIP) to investigate differences in breathing patterns between horses with and without recurrent airway obstruction (RAO) during the onset of airway obstruction induced through confinement to stables. 12 horses with no history or clinical signs of respiratory disease (control horses) and 7 RAO-affected horses. The study involved 2 phases. In phase 1, the optimal position of RIP bands for recording pulmonary function was investigated in 12 control horses. In phase 2, 7 RAO-affected and 7 control horses were confined to stables. Respiratory inductance plethysmography bands were applied to horses for 24 h/d to record respiratory rate and total displacement in 4-hour periods for 7 days or until RAO-affected horses developed signs of severe RAO that persisted for 2 consecutive days. Lung function was measured once daily. In phase 1, thoracic and abdominal cavity displacements were best represented by RIP bands positioned at intercostal spaces 6 and 17, respectively. In phase 2, pulmonary function indicated airway obstruction in the RAO-affected group on the final 2 days of stable confinement. Respiratory rate and total degree of respiratory displacement measured by RIP did not differ between the RAO-affected and control groups, but the SDs of these decreased significantly within 8 hours after stable confinement began in RAO-affected horses. Respiratory inductance plethysmography and pulmonary function findings became highly correlated as severity of disease progressed. The decrease in the SDs of RIP measurements indicated a lower degree of variability in breathing patterns of RAO-affected horses. This loss of variability may provide an early indicator of airway inflammation.

Two steps forward in bedside monitoring of lung mechanics: transpulmonary pressure and lung volume

For many decades, pressure-based respiratory mechanics have served to aid the judgment of clinicians when monitoring mechanical ventilation and making important decisions in respiratory care. However, measurements based on airway pressure (PAW) alone have limited ability to generate individualized insights for a diverse patient population with varied pathologic conditions. While the passive lungs are the primary target of attention, PAW-based interpretations may be influenced by differences in breathing pattern, alterations in chest wall activity (including diaphragmatic function), changes in lung volume, asymmetry of lung disease, abdominal distension, etc. All of these factors may complicate the interpretation of respiratory mechanics and make fixed criteria for safe ventilation difficult to apply.

Estudo do padrão respiratório e movimento toracoabdominal em valvopatia mitral

patients with mitral valve disease can progress to having pulmonary congestion, which increases the work the respiratory muscles. This overload can change the breathing pattern with a predominance of rib cage displacement or presence of paradoxical movements. a) to study the breathing pattern and thoracoabdominal movement of patients with mitral valve disease; b) to study the effect of body position on breathing parameters; and c) to correlate pulmonary hypertension with lack of coordination of thoracoabdominal movement. the breathing pattern and thoracoabdominal movement of patients with mitral valve disease were assessed using respiratory inductive plethysmography during quiet breathing in the dorsal decubitus and sitting positions for two minutes. The variables assessed were tidal volume, breathing time and thoracoabdominal movement. of the 65 patients selected, 10 were excluded, 29 were in the mitral stenosis group and 26 in the mitral regurgitation group. Tidal volume, pulmonary ventilation and mean inspiratory flow significantly increased in the sitting position, with no difference between the groups. The thoracoabdominal movement remained coordinated in all groups and positions; except for five patients in the dorsal decubitus position, who lacked coordination (three in the mitral stenosis group; two in the mitral regurgitation group). A significant correlation with pulmonary artery pressure values was observed (r = 0.992; p = 0.007). No difference in breathing pattern or thoracoabdominal movement was found between patients with mitral stenosis and regurgitation. The sitting position increased tidal volume without altering breathing times. The lack of coordination of the thoracoabdominal movement in the dorsal decubitus position was associated with pulmonary hypertension.