Breathing Variability Research Articles

A microintensive research study: The impact of yoga on posture, breathing, and psychosocial variables in young adults with cerebral palsy

Abstract The objective of the study was to demonstrate physical and psychosocial impact of yoga on adults with cerebral palsy (CP). This study was a pre–post intervention study involving 12 adults with CP selected with purposive sampling method. The participants received individualized interventions planned by a special yoga specialist for 10 months. Along with the Yoga intervention they underwent traditional physiotherapy sessions on a once-a-week basis. The participants were evaluated on the following parameters: breathing capacity, posture and physical measurements, and psychological impact. Breathing capacity was assessed using the calibrated spirometer where the maximum volume of air inspired was measured. Chest expansion measurements at rest and full inspiration were recorded at apex of axilla and at xiphoid process. The length of time of Om chanting was recorded in seconds. Physical assessments were done by measuring height, weight, body mass index (BMI), and girth of arm and thighs and a postural assessment against a postural grid. The psychosocial impact was measured using the Depression Anxiety and Stress Scale 21 items (DASS-21). There was no significant effect on BMI (P = 0.404; paired t test). There was significant improvement in the vital capacity (P = 0.04; paired t test) three ball spirometer (P = 0.003; paired t test), Om chanting (P = 0.0001; paired t test), and chest expansion at axilla and xiphoid process (P = 0.0004 and 0.002, respectively; paired t test). DASS-21 scores also showed significant differences (anxiety, P = 0.02; stress, P = 0.07; and depression, P = 0.06). It can, therefore, be concluded that yoga intervention does not impact the physical parameters of young adults with CP. It shows a positive impact on the vital capacity parameters and it also has a positive psychological impact.

Characterisation of the acute hypoxic response using breathing variability parameters: A pilot study in humans

PurposeWe aimed to investigate respiratory rate variability (RRV) and tidal volume (Vt) variability during exposure to normobaric hypoxia (i.e., reduction in the fraction of inspired oxygen - FiO2), and the association of the changes in RRV and Vt variability with the changes in pulse oxygen saturation (SpO2). MethodsThirty healthy human participants (15 females) were exposed to: (1) 15-min normoxia, (2) 10-min hypoxia simulating 2200 m, (3) 10-min hypoxia simulating 4000 m, (4) 10-min hypoxia simulating 5000 m, (5) 15-min recovery in normoxia. Linear regression modelling was applied with SpO2 (dependent variable) and the changes in RRV and Vt variability (independent variables), controlling for FiO2, age, sex, changes in heart rate (HR), changes in HR variability (HRV), and changes in minute ventilation (VE). ResultsWhen modelling breathing parameter variability as root-mean-square standard deviation (RMSSD), a significant independent association of the changes in RRV with the changes in SpO2 was found (B = −4.3e-04, 95% CI = −8.3e-04/−2.1e-05, p = 0.04). The changes in Vt variability showed no significant association with the changes in SpO2 (B = −1.6, 95% CI = −5.5/2.4, p = 0.42). When modelling parameters variability as SD, a significant independent association of the changes in RRV with the changes in SpO2 was found (B = −8.2e-04, 95% CI = −1.5e-03/−9.4e-05, p = 0.03). The changes in Vt variability showed no significant association with the changes in SpO2 (B=1.4, 95% CI = −5.8/8.6, p = 0.69). ConclusionHigher RRV is independently associated with lower SpO2 during acute hypoxic exposure, while Vt variability parameters are not. Therefore, RRV may be a potentially interesting parameter to characterize individual responses to acute hypoxia.

A motion model-guided 4D dose reconstruction for pencil beam scanned proton therapy

Objective. 4D dose reconstruction in proton therapy with pencil beam scanning (PBS) typically relies on a single pre-treatment 4DCT (p4DCT). However, breathing motion during the fractionated treatment can vary considerably in both amplitude and frequency. We present a novel 4D dose reconstruction method combining delivery log files with patient-specific motion models, to account for the dosimetric effect of intra- and inter-fractional breathing variability. Approach. Correlation between an external breathing surrogate and anatomical deformations of the p4DCT is established using principal component analysis. Using motion trajectories of a surface marker acquired during the dose delivery by an optical tracking system, deformable motion fields are retrospectively reconstructed and used to generate time-resolved synthetic 4DCTs (‘5DCTs’) by warping a reference CT. For three abdominal/thoracic patients, treated with respiratory gating and rescanning, example fraction doses were reconstructed using the resulting 5DCTs and delivery log files. The motion model was validated beforehand using leave-one-out cross-validation (LOOCV) with subsequent 4D dose evaluations. Moreover, besides fractional motion, fractional anatomical changes were incorporated as proof of concept. Main results. For motion model validation, the comparison of 4D dose distributions for the original 4DCT and predicted LOOCV resulted in 3%/3 mm gamma pass rates above 96.2%. Prospective gating simulations on the p4DCT can overestimate the target dose coverage V95% by up to 2.1% compared to 4D dose reconstruction based on observed surrogate trajectories. Nevertheless, for the studied clinical cases treated with respiratory-gating and rescanning, an acceptable target coverage was maintained with V95% remaining above 98.8% for all studied fractions. For these gated treatments, larger dosimetric differences occurred due to CT changes than due to breathing variations. Significance. To gain a better estimate of the delivered dose, a retrospective 4D dose reconstruction workflow based on motion data acquired during PBS proton treatments was implemented and validated, thus considering both intra- and inter-fractional motion and anatomy changes.

0458 Cardiovascular and sociocultural factors are associated with sleep breathing differences in a diverse Hispanic/Latino cohort

Abstract Introduction Obesity and or obstructive sleep apnea (OSA) can impact awake breathing patterns, such as increments in the breathing rate. However, little is known about their associations with breathing dysregulations during sleep beyond the apnea-hypopnea events. Understanding this could help elucidate treatment mechanisms or different pathways for disease. Furthermore, there is a strong connection between breathing patterns and cardiovascular disease, thus it is also critical to understand the links between cardiovascular risk factors and disease (CVD) and sleep breathing patterns. Methods The Hispanic Community Health Study/Study of Latinos (HCHS/SOL) is a prospective multicenter study of diverse Latinos. A total of N=16,415 participants from four major metropolitan areas and six different Hispanic/Latino backgrounds were sampled for appropriate generalization to the target population. Participants were given an ARES unirecorder device (Carlsbad, San Diego) for a single night of unsupervised at home recording (N=12,022). Raw data from cannula channel (sampled at 10Hz) was processed using the python Bycycle package. Bycycle is a cycle-by-cycle approach to analyzing time series data. Bycycle finds all peaks and throughs in cycles and allows users to extract time dependent information of cycles. We extracted breathing rate (breaths per minute), breathing variability (interquartile range of breathing rate) and time spent in inhalation phase (percent time). Results In multivariable models (N=10,175), age was linked to decreased breathing rate, breathing variability, and time spent in inhalation phase. Compared to females, males had higher breathing variability and spent more time in the inhalation phase. Compared to Mexicans and? Central Americans, Cubans, Dominicans, and Puerto Ricans had less time spent in inhalation phase. Dominicans and Puerto Ricans also had increased breathing rate compared to Mexicans. Smoking, body mass index, and moderate to severe OSA were associated with increased breathing rate and variability. Systolic, but not diastolic blood pressure, was associated with increased breathing rate. We found no significant associations with cardiovascular disease. Conclusion Factors commonly linked to OSA were associated with increased breathing rate, a compensatory mechanism for optimal oxygenation, and breathing variability. Given cessation or reduced breathing during an apnea-hypopnea event, breathing variability may add more precision to account for varying oxygen demands. Support (if any)

0308 Impact of Customized Lighting on Sleep in Hospitalized Patients

Abstract Introduction Inpatient sleep may be disrupted for myriad reasons, including lighting exposure that is typically fixed at constant intensity and spectra. In this study we employed customized lighting that promotes circadian entrainment by exposing patients to blue-augmented lighting during the morning and blue-suppressed lighting evening to improve sleep timing and duration. Methods Two Mount Sinai hospital rooms (with 2 beds each) were outfitted with Eight Mattress sensors that use a combination of movement, breathing, heart rate, and temperature variables to estimate wake and sleep vigilance states in 30-second epochs. One room contained customized lighting between 7 am and 11 pm, while the other room contained standard hospital lighting. The current analysis includes 60 participants (30 in the control room and 30 in the custom lighting room), who were matched for time-of-year hospital admission date. We first analyzed the probability of sleep during any given 30-second epoch across each subject’s admission and compared the distributions of sleep probability across the 24-hour cycle for all subjects in the lighting vs control conditions. We additionally evaluated total nocturnal sleep duration(11 PM – 7 AM) by 1) summating all sleep epochs on nights containing at least 50% valid data and 2) normalizing all measured sleep epochs to all valid sleep/wake outputs (excluding indeterminate epochs). Results The distribution of sleep probability was significantly different in the lighting vs control condition (p < 0.001) with most apparent diversion of the distributions between 9 pm and 9 am. The average raw nocturnal sleep duration was significantly higher in lighting condition (270.0 ± 23 minutes vs 201 ± 23 min in control, p = 0.037), as was the average minutes of sleep per hour of valid recording (36.9 ± 15 minutes vs 28.4 ± 13 in control, p = 0.022). There were no significant differences in the number of nocturnal wake or indeterminate epochs between conditions. Conclusion Custom lighting appears to promote sleep in hospitalized patients, but the interpretation is tempered by absence of full validation of the mattress sensor against polysomnography. Future work will evaluate differences in sleep timing and continuity between conditions. Support (if any) McClung Foundation, R01 AG066870

Breathing stability during sleep and during hypercapnia is dependent on the retrotrapezoid nucleus in adult mice

Background: Eupneic breathing during sleep is determined by the chemical drive arising from central and peripheral chemoreceptors. The retrotrapezoid nucleus (RTN) contains chemoreceptor neurons that are proposed to be critical for ventilatory responses to CO 2 . RTN chemoreceptor neurons can be identified by expression of transcripts for Neuromedin B ( Nmb + ). We hypothesized that the ablation of RTN Nmb + neurons cause alveolar hypoventilation at rest and breathing instability during sleep. Normally, in intact subjects, increasing respiratory drive with hypercapnia produces a robust and more stable breathing pattern compared to resting condition. We furhter hypothesized that in the absence of RTN, hypercapnia will not increase breathing stability and the ventilatory response to CO 2 will be impaired. Methods: Bilateral microinjections of a designer cell-ablation virus, AAV5-Flex-Casp3-TEVP, were placed in the RTN in heterozygous Cre-positive (RTN lesion) and Cre-negative (controls) Nmb-Cre mice and EEG/neck EMG electrodes were implanted. One month later, mice were tested in an unrestrained plethysmography chamber for breathing and sleep/wake recordings in normoxic conditions. Mice were exposed to hyperoxic hypercapnia (F I CO 2 up to 0.09) to assess the central respiratory CO 2 chemoreflex after RTN lesion. Arterial blood gases were also collected in unrestrained unanesthetized conditions. Values are presented as mean ±SD. Results: Ablation of the RTN was complete (<1% of total RTN Nmb + neurons remaining in RTN lesion group) and selective based on counts of neighboring catecholaminergic and serotonergic neurons. Arterial PCO 2 was increased in RTN-lesion mice (n=6) compared to controls (n=7) (49 ± 5 vs. 39 ± 3 mmHg, p<0.001) and arterial PO 2 was reduced (75 ± 11 vs. 89 ± 7 mmHg, p=0.019). Minute-ventilation was reduced in RTN-lesion mice (n=13) compared to control (n=13) (1.7 ± 0.4 vs. 2.4 ± 0.3 mL/min/g, p<0.0001) due to a reduction in tidal volume that was most evident during NREM sleep. Breathing variability was increased in RTN-lesion mice (n=9) compared to controls (n=10) during NREM (22 ± 5 vs. 10 ± 1% of inter-breath variability, p<0.001) and REM sleep (37 ± 8 vs. 25 ±7 % of inter-breath variability, p<0.01) but not during wakefulness (28 ± 9 vs. 21 ±10 % of inter-breath variability, p=0.32). The ventilatory response to CO 2 was attenuated in RTN lesion mice compared to controls (3.2 ±1 vs. 10.4 ±2 mL/min/g at FICO2 0.09, p<0.0001).Finally, during hypercapnia, breathing was more variable in RTN-lesion mice (23 ±10 vs. 3.1 ±0.4 % of inter-breath variability, p<0.0001) compared to control. Summary and conclusion: In sum, RTN neurons contribute to resting alveolar ventilation and eupneic breathing, especially during sleep. The hypercapnic ventilatory response is severely blunted and hypercapnia does not increase breathing stability in the absence of RTN. We conclude that breathing stability during sleep and during hypercapnia is dependent on the RTN. This work is funded by National Institutes of Health, R01HL148004 to Stephen BG Abbott and R01HL108609 to Douglas A Bayliss. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Capnography derived breath variability analysis feasibility and its importance for pulmonary embolism prediction

Capnography is a method that monitors the concentration of Carbon Dioxide (CO2) in patients’ respiratory gases. Its outcome, i.e., the capnographic curve shows CO2 levels plotted against time. The measurement of the carbon dioxide that is released at the end of an exhaled breath is called end-tidal carbon dioxide (etCO2). Such monitoring provides information about CO2 production and clearance. This paper hypothesizes that the capnographic curve could be useful in everyday clinical practice for differential diagnosis. Specifically, a computational analysis method was developed and a pilot study was conducted to determine if capnography can be used as a predictive indicator for Pulmonary Embolism (PE). To verify whether the respiratory pattern may have clinical significance, an assessment was carried out in patients in whom PE was diagnosed and those in whom PE was suspected but ultimately excluded. The age, gender, end-tidal-CO2 (etCO2), respiratory rate, and symptoms at the admission of patients who had a chest CT angiography were noted. Classification and regression tree analysis were designed and used to identify variables predictive for PE. A total of 120 patients (60 female, 60 males) aged 64.3 +/- 18.0 admitted to the Emergency Department had the computed tomography pulmonary angiography imaging study: 60 with positive PE and 60 with negative PE results. In patients with etCO2>=32 mmHg was a negative predictor for PE. In those with the etCO2 < 32 mmHg was predictive for PE. The developed model indicates that it could assist in predicting PE based on the etCO2 values.

Decreased breathing variability is associated with poorer outcome in mechanically ventilated patients.

Breathing is a cyclic activity that is variable by nature. Breathing variability is modified in mechanically ventilated patients. We aimed to evaluate whether decreased variability on the day of transition from assist-control ventilation to a partial mode of assistance was associated with a poorer outcome. This was an ancillary study of a multicentre, randomised, controlled trial comparing neurally adjusted ventilatory assist to pressure support ventilation. Flow and the electrical activity of the diaphragm (EAdi) were recorded within 48 h of switching from controlled ventilation to a partial mode of ventilatory assistance. Variability of flow and EAdi-related variables were quantified by the coefficient of variation, the amplitude ratio of the spectrum's first harmonic to its zero-frequency component (H1/DC) and two surrogates of complexity. 98 patients ventilated for a median duration of 5 days were included. H1/DC of inspiratory flow and EAdi were lower in survivors than in nonsurvivors, suggesting a higher breathing variability in this population (for flow, 37% versus 45%, p=0.041; for EAdi, 42% versus 52%, p=0.002). By multivariate analysis, H1/DC of inspiratory EAdi was independently associated with day-28 mortality (OR 1.10, p=0.002). H1/DC of inspiratory EAdi was lower in patients with a duration of mechanical ventilation <8 days (41% versus 45%, p=0.022). Noise limit and the largest Lyapunov exponent suggested a lower complexity in patients with a duration of mechanical ventilation <8 days. Higher breathing variability and lower complexity are associated with higher survival and lower duration of mechanical ventilation.

Individualized breathing trace quality assurance for lung radiotherapy patients undergoing 4DCT simulation.

4DCT simulation is a popular solution for radiotherapy simulation of lung cancer patients as it allows the clinician to gain an appreciation for target motion during the patient breathing cycle. Resultant binning of images and production of the 4DCT dataset relies heavily on the recorded breathing trace; but quality assurance is not routinely performed on these and there lacks any substantial recommendations thereof. An application was created for Windows in C# that was able to analyze the VXP breathing trace files from Varian RPM/RGSC and quantify various metrics associated with the patient breathing cycle. This data was then used to consider errors in voluming of targets for several example cases in order to justify recommendations on quality assurance. For 281 real patient breathing traces from 4DCT simulation of lung targets, notable differences were found between RGSC and application calculations of phase data. For any new patient without individualized QA, the average marked phase calculation (which is used for 4DCT reconstruction) is only accurate to within 19% of the actual phases. The error in BPM within the scan due to breathing rate variation is 37%. The uncertainty in amplitude due to breathing variation is 34% in the mean. Phase uncertainty leads to misbinning which we have shown can lead to missing 66% of the target for gated treatment. Variation in inhalation/exhalation level leads to voluming errors which, without individualized QA, can be assumed to be 11% (PTV is smaller than actual). Without individualized quality assurance of patient breathing traces, large uncertainties have to be assumed for metrics of both phase and amplitude, leading to clinically significant uncertainties in treatment. It is recommended to perform individualized quality assurance as this provides the clinician with an accurate quantification of uncertainty for their patient.

Selective Serotonin Reuptake Inhibitors and 5-HT2 Receptor Agonists Have Distinct, Sleep-state Dependent Effects on Postictal Breathing in Amygdala Kindled Mice

Seizures can cause profound breathing disruptions. Seizures arising from sleep cause greater breathing impairment than those emerging from wakefulness and more often result in sudden unexpected death in epilepsy (SUDEP). The neurotransmitter serotonin (5-HT) plays a major role in respiration and sleep-wake regulation. 5-HT modulates seizure susceptibility and severity and is dysregulated by seizures. Thus, the impact of seizures on breathing dysregulation may be due to impaired 5-HT neurotransmission. We examined whether pharmacologically increasing 5-HT neurotransmission prior to seizures improves postictal breathing and how sleep-state during seizure induction contributes to these effects. We assessed breathing with whole-body plethysmography in 84 amygdala-kindled mice pre-treated with selective serotonin reuptake inhibitors (SSRI) or 5-HT2 receptor agonists. SSRIs and 5-HT2 agonists increased postictal breathing frequency (fR), tidal volume (VT), and minute ventilation (VE) at different timepoints following seizures induced during wakefulness. These effects were not observed following seizures induced during NREM sleep. SSRIs suppressed ictal and postictal apnea regardless of sleep state. The SSRI citalopram and the 5-HT2 agonists TCB-2 and MK-212 decreased breathing variability following wake-occurring seizures at different postictal timepoints. Only MK-212 decreased breathing variability when seizures were induced during NREM sleep. The 5-HT2A antagonist MDL-11939 reduced the effect of citalopram on fR, VT, and VE, and enhanced its effect on breathing variability in the initial period following a seizure. These results suggest that 5-HT mechanisms that are dependent on or independent from the 5-HT2 family of receptors impact breathing on different timescales during the recovery of eupnea, and that certain serotonergic treatments may be less effective at facilitating postictal breathing following seizures emerging from sleep.

The effects of breast milk odor on the physiological and behavioral responses caused by venipuncture pain in term infants: A clinical trial study.

Pain management is very important for infants who are unable to express it verbally. Pain control is one of the nursing actions and part of their duties. This study attempted to determine the effects of breast milk odor on the physiological and behavioral responses caused by venipuncture pain in full-term infants at an educational hospital. This randomized clinical trial study was carried out on 3-5 days' term and healthy babies with a gestational age of 34 weeks and later in the 9-Day Hospital of Torbet Heydariyeh, Iran, 2021. The sample size, taking into account the possibility of a 10% dropout of samples included 20 babies for each group and a total of 40 babies were selected by convenience sampling. To collect data, a checklist of demographic characteristics, a registration form for physiological responses, and the modified behavioral pain scale were used. The results of this study showed that breast milk odor has a positive effect on behavioral responses (P < 0.001) and also a significant relationship was observed between the effects of breast milk odor and physiological responses percentage of oxygen uptake and pulse (P < 0.001). However, no significant relationship was observed between breast milk odor and breathing variables (P > 0.05). According to the results, olfactory stimulation with breast milk during venous blood sampling showed positive effects on physiological responses and pain reduction in infants. Therefore, it is recommended to use soothing stimuli such as the smell of breast milk during painful procedures in babies.

Comprehensive breathing variability indices enhance the prediction of extubation failure in patients on mechanical ventilation

Background and objectiveDespite the numerous studies on extubation readiness assessment for patients who are invasively ventilated in the intensive care unit, a 10–15% extubation failure rate persists. Although breathing variability has been proposed as a potential predictor of extubation failure, it is mainly assessed using simple statistical metrics applied to basic respiratory parameters. Therefore, the complex pattern of breathing variability conveyed by continuous ventilation waveforms may be underexplored. MethodsHere, we aimed to develop novel breathing variability indices to predict extubation failure among invasively ventilated patients. First, breath-to-breath basic and comprehensive respiratory parameters were computed from continuous ventilation waveforms 1 h before extubation. Subsequently, the basic and advanced variability methods were applied to the respiratory parameter sequences to derive comprehensive breathing variability indices, and their role in predicting extubation failure was assessed. Finally, after reducing the feature dimensionality using the forward search method, the combined effect of the indices was evaluated by inputting them into the machine learning models, including logistic regression, random forest, support vector machine, and eXtreme Gradient Boosting (XGBoost). ResultsThe coefficient of variation of the dynamic mechanical power per breath (CV-MPd[J/breath]) exhibited the highest area under the receiver operating characteristic curve (AUC) of 0.777 among the individual indices. Furthermore, the XGBoost model obtained the best AUC (0.902) by combining multiple selected variability indices. ConclusionsThese results suggest that the proposed novel breathing variability indices can improve extubation failure prediction in invasively ventilated patients.

Breathing Pattern Estimation Using Wearable Bioimpedance for Assessing COPD Severity.

Breathing pattern has been shown to be different in chronic obstructive pulmonary disease (COPD) patients compared to healthy controls during rest and walking. In this study we evaluated respiratory parameters and the breathing variability of COPD patients as a function of their severity. Thoracic bioimpedance was acquired on 66 COPD patients during the performance of the six-minute walk test (6MWT), as well as 5 minutes before and after the test while the patients were seated, i.e. resting and recovery phases. The patients were classified by their level of airflow limitation into moderate and severe groups. We characterized the breathing patterns by evaluating common respiratory parameters using only wearable bioimpedance. Specifically, we computed the median and the coefficient of variation of the parameters during the three phases of the protocol, and evaluated the statistical differences between the two COPD severity groups. We observed significant differences between the COPD severity groups only during the sitting phases, whereas the behavior during the 6MWT was similar. Particularly, we observed an inverse relationship between breathing pattern variability and COPD severity, which may indicate that the most severely diseased patients had a more restricted breathing compared to the moderate patients.

Comparing heart rate variability biofeedback and simple paced breathing to inform the design of guided breathing technologies

IntroductionA goal of inbodied interaction is to explore how tools can be designed to provide external interactions that support our internal processes. One process that often suffers from our external interactions with modern computing technology is our breathing. Because of the ergonomics and low-grade-but-frequent stress associated with computer work, many people adopt a short, shallow breathing pattern that is known to have a negative effect on other parts of our physiology. Breathing guides are tools that help people match their breathing patterns to an external (most often visual) cue to practice healthy breathing exercises.However, there are two leading protocols for how breathing cues are offered by breathing guides used in non-clinical settings: simple paced breathing (SPB) and Heart Rate Variability Biofeedback (HRV-b). Although these protocols have separately been demonstrated to be effective, they differ substantially in their complexity and design. Paced breathing is a simpler protocol where a user is asked to match their breathing pattern with a cue paced at a predetermined rate and is simple enough to be completed as a secondary task during other activities. HRV-b, on the other hand, provides adaptive, real-time guidance derived from heart rate variability, a physiological signal that can be sensed through a wearable device. Although the benefits of these two protocols have been well established in clinical contexts, designers of guided breathing technology have little information about whether one is better than the other for non-clinical use.MethodsTo address this important gap in knowledge, we conducted the first comparative study of these two leading protocols in the context of end-user applications. In our N=28 between-subject design, participants were trained in either SPB or HRV-b and then completed a 10-minute session following their training protocol. Breathing rates and heart rate variability scores were recorded and compared between groups.Results and discussionOur findings indicate that the exercises did not significantly differ in their immediate outcomes – both resulted in significantly slower breathing rates than their baseline and both provided similar relative increases in HRV. Therefore, there were no observed differences in the acute physiological effects when using either SPB or HRV-b. Our paper contributes new findings suggesting that simple paced breathing – a straightforward, intuitive, and easy-to-design breathing exercise – provides the same immediate benefits as HRV-b, but without its added design complexities.

Short-term cognitive loading deteriorates breathing pattern and gas exchange in adult patients with congenital central hypoventilation syndrome.

Human PHOX2B mutations result in life-threatening sleep-related hypoventilation (congenital central hypoventilation syndrome, CCHS). Most patients retain ventilatory activity when awake through a respiratory-related cortical network. We hypothesised that this need to mobilise cortical resources to breathe would lead to breathing-cognition interferences during cognitive loading. Seven adult CCHS patients (five women; median age 21) performed standard neuropsychological tests (paced auditory serial addition test - calculation capacity, working memory, sustained and divided attention; trail making test - visuospatial exploration capacity, cognitive processing speed, attentional flexibility; Corsi block-tapping test - visuospatial memory, short-term memory, working memory) during unassisted breathing and under ventilatory support. Ventilatory variables and transcutaneous haemoglobin oxygen saturation were recorded. Cortical connectivity changes between unassisted breathing and ventilatory support were assessed using electroencephalographic recordings (EEG). Baseline performances were lower than expected in individuals of this age. During unassisted breathing, cognitive loading coincided with increased breathing variability, and decreases in oxygen saturation inversely correlated with an increasing number of apnoeic cycles per minute (rho -0.46, 95% CI -0.76 to -0.06, p=0.01). During ventilatory support, cognitive tasks did not disrupt breathing pattern and were not associated with decreased oxygen saturation. Ventilatory support was associated with changes in EEG cortical connectivity but not with improved test performances. Acute cognitive loads induce oxygen desaturation in adult CCHS patients during unassisted breathing, but not under ventilatory support. This justifies considering the use of ventilatory support during mental tasks in CCHS patients to avoid repeated episodes of hypoxia.

A Descriptive Study of Speech Breathing in Children With Cerebral Palsy During Two Types of Connected Speech Tasks.

This study examined speech breathing during two connected speech tasks in children with cerebral palsy (CP) and typically developing (TD) peers. Understanding how the respiratory system supports speech production during various speech tasks can help researchers construct appropriate models of speech production and clinicians remediate speech disorders effectively. Four children with CP and four age- and sex-matched TD peers completed two speech tasks, reading and extemporaneous speech. Respiratory kinematic and acoustic data were collected. Dependent variables included utterance length, speech rate, sound pressure level, and lung volume variables. Based on descriptive results, children with CP and speech motor involvement demonstrated reduced utterance length and speech rate, equivalent intensity levels, and changes in lung volume variables indicative of respiratory physiological impairment as compared to their TD peers. However, children with CP and no speech motor involvement exhibited speech production and speech breathing variables in the more typical range. In relation to task effects, the majority of children (CP and TD) produced shorter utterances, slower speech rates, equivalent intensity levels, higher lung volume initiation, termination, excursion, higher percent vital capacity per syllable, and longer inspiratory duration during extemporaneous speech as compared to reading. Two major themes emerged from the data: (a) Children with CP, particularly those with concomitant speech motor involvement, demonstrate different speech production and speech breathing patterns than their TD peers. (b) Speech task impacts speech production and speech breathing variables in both children with CP and their TD peers, but the extemporaneous speech task did not seem to exaggerate group differences.

Abstract 9881: Effects of CPAP on Very Short-Term Blood Pressure Variability Associated With Sleep-Disordered Breathing Determined by Pulse-Transit-Time-Based Blood Pressure Measurements

Background: Sleep-disordered breathing (SDB) and blood pressure (BP) variability are closely associated with cardiovascular diseases. We have recently reported that pulse-transit-time (PTT) has enabled to monitor the beat-to-beat BP, identifying a strong relationship between the severity of SDB and the extent to very short-term BP variability. Here, we investigated the effects of continuous positive airway pressure (CPAP) on very short-term BP variability. Methods: We studied 57 patients (mean age 61 years old, male 42) with SDB who underwent the full polysomnography on two consecutive days for diagnosis (baseline) and CPAP. PTT was continuously monitored together, and PTT-based BP values were measured on a beat-to-beat basis. PTT index was defined as the average number of acute transient rises in BP (≥12 mmHg) within 30 seconds per hour. Results: Apnea-hypopnea index (AHI) was decreased from 46.5±22.4 to 13.7±15.0 (P&lt;0.01) by CPAP. CPAP significantly lowered the average value of systolic PTT-based BP from 121±21 to 118±20 mmHg (P=0.04). Importantly, CPAP significantly reduced the PTT index from 31.4±20.1 to 20.8±15.6 (P&lt;0.01) as well as the standard deviation (SD) of systolic PTT-BP from 5.3±1.9 to 4.9±1.4 mmHg (P=0.01), suggesting that very short-term BP variability was improved by CPAP ( Figure ). The changes in PTT index after CPAP were significantly correlated with the improvement in AHI (R=0.55), oxygen desaturation index (R=0.36), minimal SpO 2 (R=0.48), mean SpO 2 (R=0.46), and arousal index (R=0.58). In multivariate linear regression analysis, the change in AHI was the independent factor to determine the reduction of the PTT index after CPAP. Conclusion: PTT-based BP discovered the improvement in very short-term BP variability associated with SDB events by CPAP therapy.

Diet-induced obesity leads to sleep fragmentation independently of the severity of sleep-disordered breathing.

Obesity is associated with sleep-disordered breathing (SDB) and unrefreshing sleep. Residual daytime sleepiness and sleep impairments often persist after SDB treatment in patients with obesity, which suggests an independent effect of obesity on breathing and sleep. However, examining the relationship between sleep architecture and SDB in patients with obesity is complex and can be confounded by multiple factors. The main goal of this study was to examine the relationship between obesity-related changes in sleep architecture and SDB. Sleep recordings were performed in 15 lean C57BL/6J and 17 diet-induced obesity (DIO) mice of the same genetic background. Arousals from sleep and apneas were manually scored. Respiratory arousals were classified as events associated with ≥30% drops in minute ventilation (VE) from baseline. We applied Poincaré analysis of VE during sleep to estimate breathing variability. Obesity augmented the frequency of arousals by 45% and this increase was independent of apneas. Respiratory arousals comprised only 15% of the arousals in both groups of mice. Breathing variability during non-rapid-eye-movment (NREM) sleep was significantly higher in DIO mice, but it was not associated with arousal frequency. Our results suggest that obesity induces sleep fragmentation independently of SDB severity.NEW & NOTEWORTHY Our diet-induced obesity (DIO) model reproduces sleep features of human obesity, including sleep fragmentation, increased apnea frequency, and larger breathing variability. DIO induces sleep fragmentation independently of apnea severity. Sleep fragmentation in DIO mice is mainly attributed to non-respiratory arousals. Increased breathing variability during sleep did not account for the higher arousal frequency in DIO. Our results provide a rationale to examine sleep in patients with obesity even when they are adequately treated for sleep-disordered breathing.

Investigating the Dose-Response Relationship between Deep Breathing and Heart Rate Variability in Healthy Participants and Across-Days Reliability in Patients with Rheumatoid Arthritis and Systemic Lupus Erythematosus.

Rheumatoid Arthritis (RA) and Systemic Lupus Erythematosus (SLE) are associated with autonomic dysfunction, potentially through reduced vagus nerve tone. Vagus nerve stimulation has been proposed as an anti-inflammatory treatment, and it can be performed through deep breathing (DB) exercises. In this study, the dose-response relationship between DB exercises and heart rate variability (HRV) was investigated in healthy participants and reliability across days in patients with RA and SLE. On three separate days, 41 healthy participants performed DB for: 5, 15, or 30 min. On two separate days, 52 RA or SLE patients performed DB with the dose associated with the highest HRV increase in healthy participants. The HRV was estimated from ECG-recordings recorded prior and post the DB exercises. Increases in dose led to larger HRV-responses. Thirty minutes led to the largest HRV-response. In the RA and SLE patients, this dose increased the HRV-parameters consistently across the two days, indicating reliability. DB increases HRV in healthy participants and RA or SLE patients, which indicates stimulation of the vagus nerve. Of the tested durations, 30 min of DB was the optimal period of stimulation. A potential anti-inflammatory effect of DB exercises should be investigated in future studies.

Cardiorespiratory alterations following intermittent photostimulation of RVLM C1 neurons: Implications for long-term blood pressure, breathing and sleep regulation in freely moving rats.

Sympathoexcitation and sleep-disordered breathing are common contributors for disease progression. Catecholaminergic neurons from the rostral ventrolateral medulla (RVLM-C1) modulate sympathetic outflow and have anatomical projections to respiratory neurons; however, the contribution of highly selective activation of RVLM-C1 neurons on long-term autonomic and breathing (dys)regulation remains to be understood. To explore this relationship, a lentiviral vector carrying the light-sensitive cation channel channelrhodopsin-2 (LVV-PRSX8-ChR2-YFP) was unilaterally injected into the RVLM of healthy rats. On the contralateral side, LVV-PRSX8-ChR2-YFP was co-injected with a specific immunotoxin (DβH-SAP) targeted to eliminate C1 neurons. Intermittent photostimulation of RVLM-C1 in vivo, in unrestrained freely moving rats, elicited long-term facilitation of the sympathetic drive, a rise in blood pressure and sympatho-respiratory coupling. In addition, photoactivation of RVLM-C1 induced long-lasting ventilatory instability, characterized by oscillations in tidal volume and increased breathing variability, but only during non-rapid eye movement sleep. These effects were not observed when photostimulation of the RVLM was performed in the presence of DβH-SAP toxin. The finding that intermittent activation of RVLM-C1 neurons induces autonomic and breathing dysfunction suggest that episodic stimulation of RVLM-C1 may serve as a pathological substrate for the long-term development of cardiorespiratory disorders.