Breathing Pattern In Patients Research Articles

Respiratory pattern complexity in newly-diagnosed asthmatic patients

BackgroundThe intensity of respiratory symptoms and expiratory airflow limitations in asthma fluctuate over time. Some studies have reported variable complexity of the respiratory patterns in asthmatic patients. Thus, we conducted a novel study to assess the correlation between asthma severity and breathing pattern dynamics in newly-diagnosed asthmatic patients. MethodsA total of 20 newly-diagnosed asthmatic patients (7 male, 13 female) and 20 healthy cases (11 male, 9 female) were included. The respiratory patterns of all participants and the asthma severity for asthmatic patients were measured using a spirometer (before and after a bronchodilator exposure) and airflow recorder, respectively. The peak-to-peak intervals and the amplitude of peaks were considered as the inter-breath interval (IBI) and lung volume (LV) series. The Detrended Fluctuation Analysis (DFA), Sample Entropy (SampEn), Multi-scale Entropy (MSE), short-term (SD1) and long-term (SD2) variability, and IBI and LV Cross-Sample Entropy of the respiratory pattern dynamics were calculated using MATLAB (Mathwork, USA). ResultsAsthma patients showed notable increase in the average of sample entropy in both IBI and LV parameters (p = 0.025 and p = 0.018, respectively) and also decreased synchronization between IBI and LV (p = 0.042). The multi-scale sample entropy of both IBI and LV was significantly higher in asthmatic patients (p < 0.05). Furthermore, SD1 and SD2 were higher in the patients with asthma (p < 0.05). Significant correlations were detected between spirometric (forced expiratory flow (FEF) change, pre FEF, pre forced expiratory volume in one second (FEV1) / forced vital capacity (FVC), FVC change) and respiratory pattern (mean-IBI, mean-LV, mean-respiratory rate (RR), coefficient of variation (CV)-IBI, CV-LV, cross-sample entropy) parameters (p < 0.05). Furthermore, we identified a negative correlation between CV of IBI and asthma severity (r = −0.52, p = 0.021). ConclusionHere, we took a novel approach and observed increased irregularity (more complexity) in the breathing pattern of patients newly-diagnosed with asthma. Remarkable correlations were detected between breathing complexity markers and spirometric indices along with disease severity in asthmatic patients. Thus, our data suggests respiratory pattern indices could be utilized as an indicator of asthma and its severity. However, more clinical data are required to support this conclusion.

Classification and occurrence of an abnormal breathing pattern during cardiopulmonary exercise testing in subjects with persistent symptoms following COVID-19 disease.

Reduced exercise capacity and several limiting symptoms during exercise have been reported following severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2) infection. From clinical observations, we hypothesized that an abnormal breathing pattern (BrP) during exercise may be common in these patients and related to reduced exercise capacity. We aimed to (a) evaluate a method to classify the BrP as normal/abnormal or borderline in terms of inter‐rater agreement; (b) determine the occurrence of an abnormal BrP in patients with post‐COVID; and (c) compare characteristics of post‐COVID patients with normal and abnormal BrP. In a retrospective, cross‐sectional study of patients referred for CPET due to post‐COVID April 2020–April 2021, we selected subjects without a history of intensive care and with available medical records. Three raters independently categorized patients’ BrP as normal, abnormal, or borderline, using four traditional CPET plots (respiratory exchange ratio, tidal volume over ventilation, ventilatory equivalent for oxygen, and ventilation over time). Out of 20 patients (11 male), 10 were categorized as having a normal, 7 an abnormal, and three a borderline BrP. Inter‐rater agreement was good (Fleiss’ kappa: 0.66 [0.66–0.67]). Subjects with an abnormal BrP had lower peak ventilation, lower exercise capacity, similar ventilatory efficiency and a similar level of dyspnea at peak exercise, as did subjects with a normal BrP. Patients’ BrP was possible to classify with good agreement between observers. A third of patients had an abnormal BrP, associated with lower exercise capacity, which could possibly explain exercise related symptoms in some patients with post‐COVID syndrome.

Optimizing high-flow nasal cannula flow settings in adult hypoxemic patients based on peak inspiratory flow during tidal breathing

BackgroundOptimal flow settings during high-flow nasal cannula (HFNC) therapy are unknown. We investigated the optimal flow settings during HFNC therapy based on breathing pattern and tidal inspiratory flows in patients with acute hypoxemic respiratory failure (AHRF).MethodsWe conducted a prospective clinical study in adult hypoxemic patients treated by HFNC with a fraction of inspired oxygen (FIO2) ≥ 0.4. Patient’s peak tidal inspiratory flow (PTIF) was measured and HFNC flows were set to match individual PTIF and then increased by 10 L/min every 5–10 min up to 60 L/min. FIO2 was titrated to maintain pulse oximetry (SpO2) of 90–97%. SpO2/FIO2, respiratory rate (RR), ROX index [(SpO2/FIO2)/RR], and patient comfort were recorded after 5–10 min on each setting. We also conducted an in vitro study to explore the relationship between the HFNC flows and the tracheal FIO2, peak inspiratory and expiratory pressures.ResultsForty-nine patients aged 58.0 (SD 14.1) years were enrolled. At enrollment, HFNC flow was set at 45 (38, 50) L/min, with an FIO2 at 0.62 (0.16) to obtain an SpO2/FIO2 of 160 (40). Mean PTIF was 34 (9) L/min. An increase in HFNC flows up to two times of the individual patient’s PTIF, incrementally improved oxygenation but the ROX index plateaued with HFNC flows of 1.34–1.67 times the individual PTIF. In the in vitro study, when the HFNC flow was set higher than PTIF, tracheal peak inspiratory and expiratory pressures increased as HFNC flow increased but the FIO2 did not change.ConclusionMean PTIF values in most patients with AHRF were between 30 and 40 L/min. We observed improvement in oxygenation with HFNC flows set above patient PTIF. Thus, a pragmatic approach to set optimal flows in patients with AHRF would be to initiate HFNC flow at 40 L/min and titrate the flow based on improvement in ROX index and patient tolerance.Trial registration: ClinicalTrials.gov (NCT03738345). Registered on November 13th, 2018. https://clinicaltrials.gov/ct2/show/NCT03738345?term=NCT03738345&draw=2&rank=1

Acute effects of expiratory positive airway pressure on exercise tolerance in patients with COPD

ABSTRACT Objective: To evaluate the acute effects of expiratory positive airway pressure (EPAP) on exercise tolerance, dyspnea, leg discomfort, and breathing pattern in patients with COPD. Methods: Fifteen patients with COPD were assessed with the following three different protocols: EPAP of 7.5 cmH2O used during a constant cycle ergometer exercise test (Protocol-1); EPAP of 7.5 cmH2O used for 15 minutes before the test (Protocol-2); and a sham system without pressure used for 15 minutes before the test (Protocol-3). Dyspnea and leg discomfort were assessed using Borg scale, whereas breathing pattern by optoelectronic plethysmography. Statistical analyses were performed using generalized estimating equations and Bonferroni tests (α = 5%), considering the protocols (1, 2, and 3) and moment (resting and the end of exercise). Results: Exercise tolerance was lower in protocol 1: 108 ± 45 seconds compared to protocols 2: 187 ± 99 seconds (p= .011) and 3: 183 ± 101 seconds (p= .021). No difference was observed between protocols 2 and 3 (p> .999). Dyspnea in protocol 1: 7.0 ± 2.08 was higher than protocols 2: 4.10 ± 2.45 (p= .001) and 3: 3.90 ± 2.21 (p< .001), but no differences were observed between protocols 2 and 3 (p> .999). No significant difference was observed for leg discomfort among the protocols (p= .137). There were no statistically significant differences for most variables of breathing pattern among the protocols. Conclusion: A reduction on exercise tolerance and an increase in dyspnea were found with EPAP of 7.5 cm H2O during a constant cycle ergometer exercise test in patients with COPD.

Fugitive aerosols in the intensive care unit: a narrative review.

The risk of unintended inhalation of fugitive aerosols is becoming a topic of increasing interest in the healthcare arena. These fugitive aerosols may be bioaerosols, generated by the patient themselves through cough or sneeze, or they may be therapeutic medical aerosols, generated by therapeutic medical aerosol generators with the intent of delivery to a specific patient's respiratory tract. This review focus' on therapeutic aerosols in the intensive care unit (ICU) only, those typically generated by nebulisers. In the intensive care environment, patients are generally in receipt of ventilatory support, and the literature suggests that these different support interventions influence fugitive therapeutic medical aerosol emissions in a variety of ways. Predominant ventilatory support interventions include, but are not limited to, invasive mechanical ventilation (MV), non-invasive mechanical ventilation (NIV), high flow nasal therapy (HFNT), and supplemental oxygen delivery in spontaneously breathing patients. Further, factors such as nebuliser type, patient interface, patient breathing pattern, nebuliser position in the patient breathing circuit and medication formulation characteristics also have been shown to exert influence on aerosol concentrations and distance from the source. Here we present the state of the art knowledge in this, as yet, poorly described field of research, and identify the key risks, and subsequently, opportunities to mitigate the risks of unintended exposure of both patients and bystanders during and for periods following the administration of therapeutic aerosols.

Last Word on Viewpoint: Nondyspnogenic acute hypoxemic respiratory failure in COVID-19 pneumonia-Breathing pattern in patients with SARS-CoV-2.

Last Word on Viewpoint: Nondyspnogenic acute hypoxemic respiratory failure in COVID-19 pneumonia-Breathing pattern in patients with SARS-CoV-2.

In vitro evaluation of disposable transport ventilators with combination aerosol therapy

BackgroundThe COVID-19 pandemic has highlighted the need for alternative short-term, reliable means to aid in the treatment of patients requiring ventilatory support. Concurrent aerosol drug delivery is often prescribed to...

Effect of continuous positive airway pressure associated to exercise on the breathing pattern and heart rate variability of patients undergoing coronary artery bypass grafting surgery: a randomized controlled trial.

Continuous positive airway pressure (CPAP) has been used to improve gas exchange and diaphragmatic function, among others benefits. Moreover, it can be used to increase exercise tolerance and positively influence ventilatory function and breathing pattern (BP) during exercise. However, there is no information about the long-term effects of CPAP, as an adjunct to an inpatient cardiac rehabilitation (CR) program, on BP and heart rate variability (HRV) of patients after coronary artery bypass grafting surgery (CABG). Twenty patients were allocated to receive, after randomization, standard inpatient CR without CPAP (control group - CG) or CR with CPAP between 10 to 12 cmH2O (CPAP group - CPG) associated with the exercises. Participants were assessed preoperatively and on the discharge day, in the sitting rest position. Outcome measurements included BP variables, collected by respiratory inductive plethysmography, and HRV, collected by polar precision performance. The CPG presented lower values of percent rib cage inspiratory and expiratory contributions to tidal volume (%RCi and %RCe) at discharge time, compared to CG. No statistical differences between groups were observed for HRV variables and both groups presented lower values of these indices, compared to preoperative ones. In this context, the patients who received CPAP throughout the whole rehabilitation program were discharged with a better BP, which could indicate more synchronized breathing. CPAP did not influence cardiac autonomic modulation in the long term.

Effects of inspiratory muscle training on resting breathing pattern in patients with advanced lung disease

AimThe aim of this study was to evaluate the effects of interval high intensity inspiratory muscle training (IMT) on resting breathing pattern in patients with advanced lung disease. MethodsIMT was performed daily and training load set at 50 % of the maximal inspiratory pressure. Participants were evaluated at pre-IMT, post 8 weeks of IMT and follow-up (3 months after the end of IMT). Breathing pattern (volume and time variables as well as percentages of contribution to tidal volume) was evaluated by Optoelectronic Plethysmography at rest. Friedman test was used to verify the differences between the three time-points (p < 0.05). ResultsNineteen patients (54 ± 16 years old; 5 males) were evaluated at pre-IMT and post-IMT and fourteen were assessed at follow-up. There was no significant difference (p > 0.05) in any comparison for all evaluated breathing pattern variables at the three time-points. ConclusionResting breathing pattern was not significantly changed after 8 weeks of IMT in patients with advanced lung disease.

Transvenous Phrenic Nerve Stimulation is Safe and Effective in Patients with Heart Failure and Cheyne-stokes Respiration

Introduction The most common type of central sleep apnea (CSA) breathing pattern in patients with heart failure (HF) is Cheyne-Stokes respiration (CSR). CSR manifests as a cyclical pattern of apnea and hyperventilation, with absence of airflow and respiratory effort followed by hyperventilation in a crescendo-decrescendo pattern. CSR may be a predictor of negative clinical outcomes in HF patients. Purpose Examine the response to transvenous phrenic nerve stimulation (TPNS) in patients with HF and different amounts of CSR. Methods Patients with CSA and HF who participated in the remedē System Pivotal Trial were divided into clinically relevant subgroups based on percentage of sleep in CSR (%CSR: 50%) during their baseline polysomnogram. The subgroups were analyzed for efficacy and safety by randomized group (TPNS vs control [no TPNS]). Epworth sleepiness scale (ESS) was also collected. Results At baseline, higher percentage CSR subgroups had lower left ventricular ejection fraction (median 45% for CSR 50%). Baseline apnea-hypopnea index (AHI) indicated severe CSA in all subgroups. All CSR subgroups receiving TPNS therapy had more than 50% of patients achieve ≥50% reduction in AHI at 6 months (see Table); control response rates were ≤11% in each CSR subgroup. The AHI decreased by ≥21 events/hour in each CSR subgroup on therapy while Control subgroups had little or no improvement. The central apnea index decreased to median ≤3 events/hour in each TPNS CSR subgroup; each control subgroup had median 22-24 events/hour remaining at 6 months. Baseline daytime sleepiness was worse in lower %CSR subgroups, however improved in all subgroups. No apparent relationship existed between %CSR and cardiovascular death in patients using TPNS therapy through 6 months, with the only death being in the 20-50% CSR subgroup; the death was determined not related to device, therapy or procedure by the clinical events committee. Further, 2/22 control subjects with CSR>50% experienced a cardiovascular death compared to 0/12 in the TPNS treated subgroup. Conclusions Transvenous phrenic nerve stimulation can treat CSA in HF patients regardless of the percentage of sleep in CSR and no signal of increased mortality was observed.

A New Nasal Restriction Device Called FeelBreathe® Improves Breathing Patterns in Chronic Obstructive Pulmonary Disease Patients during Exercise.

A device called FeelBreathe (FB)® was designed, developed, and patented for inspiratory muscle training. The main aim was to determine the acute responses on lung ventilation, gas exchange, and heart rate during exercise in patients with chronic obstructive pulmonary disease (COPD) with and without the use of FB. In this study, a randomized cross-over trial was performed with 18 men diagnosed with COPD (FEV1 between 30% and 70% of its predicted value). Each participant randomly conducted two trials with 30 min of rest between them with the same protocol on a treadmill for 10 min at a constant rate of 50% of VO2peak. Each test was performed randomly and in a crossover randomized design in two different conditions: (1) oronasal breathing; and (2) nasal breathing with FB (nasal ventilatory flow restriction device). It was observed that FB had positive effects on dynamic hyperinflation, breathing pattern, and breathing efficiency, with higher expiratory and inspiratory time. Despite these differences, blood oxygen saturation percentage, oxygen uptake, and heart rate showed a similar response for both conditions during exercise. The results suggest that exercise performed with FB improved ventilatory responses compared to the oronasal mode in COPD patients. This new tool could be used during most daily tasks and exercise programs.

Prevalence of Diaphragm Dysfunction in Relation to Breathing Pattern in Non Specific Low Back Pain

Background: Low Back pain is commonly seen clinical condition which is encountered in day to day practice of Physiotherapy. There is lack of studies correlating the relationship between the diaphragm and low back pain. Purpose: The aim of the study was to observe the diaphragm dysfunction with relation to the breathing pattern in individuals with low back pain. Material and Method: The materials used in this study is Pen, pencil and the data collection sheet. An observational study was carried out using a cross sectional study design. The study was carried in Karad city, Maharashtra, India. 80 Participants with low back pain [37:M;43:F] has been participated in the study. The diaphragm weakness and breathing pattern were evaluated at rest as well as after motor task with the help of Manual Assessment of Respiratory Motion and pulmonary Function Test. Result: Observational findings of this study demonstrates partial weakness and altered breathing pattern in patients with low back pain. Conclusion: Partial diaphragm weakness and an altered breathing pattern was found in individuals with low back pain.

A multidisciplinary approach to prevent and treat pressure sores in proned COVID-19 patients at a quaternary university hospital

An estimated 10-15% of patients with respiratory disease resulting from coronavirus disease 2019 (COVID-19) develop acute respiratory failure and require intensive care (). In order to improve breathing patterns in patients with severe acute respiratory syndrome (SARS), prone positioning can make ventilation more efficient. Proning minimizes ventral alveolar distension and reduces dorsal alveolar collapse by decreasing the difference between dorsal and ventral transpulmonary pressure. It also prevents compression of the lungs, consequently improving blood perfusion and gas exchange (). When [...]

New physiological bench test reproducing nocturnal breathing pattern of patients with sleep disordered breathing.

Previous studies have shown that Automatic Positive Airway Pressure devices display different behaviors when connected to a bench using theoretical respiratory cycle scripts. However, these scripts are limited and do not simulate physiological behavior during the night. Our aim was to develop a physiological bench that is able to simulate patient breathing airflow by integrating polygraph data. We developed an algorithm analyzing polygraph data and transformed this information into digital inputs required by the bench hardware to reproduce a patient breathing profile on bench. The inputs are respectively the simulated respiratory muscular effort pressure input for an artificial lung and the sealed chamber pressure to regulate the Starling resistor. We did simulations on our bench for a total of 8 hours and 59 minutes for a breathing profile from the demonstration recording of a Nox T3 Sleep Monitor. The simulation performance results showed that in terms of relative peak-valley amplitude of each breathing cycle, simulated bench airflow was biased by only 1.48% ± 6.80% compared to estimated polygraph nasal airflow for a total of 6,479 breathing cycles. For total respiratory cycle time, the average bias ± one standard deviation was 0.000 ± 0.288 seconds. For patient apnea events, our bench simulation had a sensitivity of 84.7% and a positive predictive value equal to 90.3%, considering 149 apneas detected both in polygraph nasal simulated bench airflows. Our new physiological bench would allow personalizing APAP device selection to each patient by taking into account individual characteristics of a sleep breathing profile.

Optimization of motion management parameters in a synchrotron-based spot scanning system.

PurposeTo quantify the effects of combining layer‐based repainting and respiratory gating as a strategy to mitigate the dosimetric degradation caused by the interplay effect between a moving target and dynamic spot‐scanning proton delivery.MethodsAn analytic routine modeled three‐dimensional dose distributions of pencil‐beam proton plans delivered to a moving target. Spot positions and weights were established for a single field to deliver 100 cGy to a static, 15‐cm deep, 3‐cm radius spherical clinical target volume with a 1‐cm isotropic internal target volume expansion. The interplay effect was studied by modeling proton delivery from a clinical synchrotron‐based spot scanning system and respiratory target motion, patterned from surrogate patient breathing traces. Motion both parallel and orthogonal to the beam scanning direction was investigated. Repainting was modeled using a layer‐based technique. For each of 13 patient breathing traces, the dose from 20 distinct delivery schemes (combinations of four gate window amplitudes and five repainting techniques) was computed. Delivery strategies were inter‐compared based on target coverage, dose homogeneity, high dose spillage, and delivery time.ResultsNotable degradation and variability in plan quality were observed for ungated delivery. Decreasing the gate window reduced this variability and improved plan quality at the expense of longer delivery times. Dose deviations were substantially greater for motion orthogonal to the scan direction when compared with parallel motion. Repainting coupled with gating was effective at partially restoring dosimetric coverage at only a fraction of the delivery time increase associated with very small gate windows alone. Trends for orthogonal motion were similar, but more complicated, due to the increased severity of the interplay.ConclusionsLayer‐based repainting helps suppress the interplay effect from intra‐gate motion, with only a modest penalty in delivery time. The magnitude of the improvement in target coverage is strongly influenced by individual patient breathing patterns and the tumor motion trajectory.

Comparisons for the Abnormality of Breathing Pattern, Kinesiophobia and Flexion Relaxation Phenomenon in Patients with Chronic Low Back Pain and Healthy Person during Flexion and Extension of the Trunk

Background: Most of the previous researches on the abnormality of breathing pattern have focused on the silence of functional movements owing to such abnormality, however, have not been clearly identified the relationship between the abnormal breathing pattern on one hand and kinesiophobia and flexion relaxation phenomenon (FRP) on the other hand. Objective: To compare patients with chronic low back pain (CLBP) and healthy person in the abnormality of breathing pattern, kinesiophobia, and FRP during flexion and extension of the trunk. Design: Case-control study. Methods: The research subjects consisted of a group of 15 healthy adults and another group of 15 patients with CLBP. Capnography was used to measure the endtidal CO2 (EtCO2) and respiratory quotient (RQ). The muscle activity of multifidus and erector spinae of the subjects was measured during flexion and extension of the trunk to identify their FRP. The Nijmegen Questionnaire (NQ) and Tampa Scale of Kinesiophobia (TSK) were utilized to measure their breathing patterns and kinesiophobia, respectively. The Kolmogorov-Smirnov (K-S) test was conducted in order to analyze the normal distribution of the measured data. Their general characteristics were identified by the descriptive statistics and the independent t-test was performed to identify the differences between the two groups in terms of abnormality of breathing pattern, kinesiophobia, and FRP. The level of significance was set at α=.05. Results: The patients with CLBP had significantly less EtCO2 and shorter breathing hold time (BHT) than normal healthy person (p<.05). The patient with CLBP also had significantly greater kinesiophobia than healthy person (p<.05), and had less FRP than the healthy person (p<.01). Conclusions: These results suggest that the CLBP had greater abnormality of breathing pattern and kinesiophobia with less FRP than healthy person.

Effect of continuous positive airway pressure on respiratory drive in patients with obstructive sleep apnea

ObjectivePatients with obstructive sleep apnea (OSA) have an altered control of breathing during wakefulness. Thus far, whether and how treatment with continuous positive airway pressure (CPAP) may restore these abnormalities has been poorly understood. The aim of this study was to investigate the long-term effects of CPAP on the breathing pattern, ventilatory drive (VDr), and chemoreceptor sensitivity in OSA patients. Patients and methodsThis was a prospective, observational study, carried out in an academic sleep outpatient clinic. A total of 62 patients with OSA (mean age [SD], 51 [11] years) underwent polysomnography (PSG), breathing pattern assessment, mouth occlusion pressure, ventilatory response to hypoxemia (Ve/SaO2), and hypercapnia (Ve/PETCO2) before and after CPAP titration and during 12-month follow-up. A total of 48 age-matched healthy subjects served as controls. Patients with good (≥6 h/night) and poor (<6 h/night) compliance with CPAP were also compared. ResultsAt baseline, VDr as well as thoracic and inspiratory impedances were greater in patients with OSA compared with controls and were reduced by CPAP treatment, starting from the night of titration (P < 0.01), especially in patients with good compliance with CPAP. Baseline Ve/SaO2 was higher in OSA patients (P < 0.05) and was progressively normalized during CPAP treatment (P < 0.001). The pathophysiological changes were mainly due to a reduction in tidal volume. The remaining breathing pattern parameters were unaltered by CPAP treatment and were similar between groups. ConclusionIn OSA patients, the mechanics of breathing are inefficient because of an imbalance of the VDr. Regular CPAP treatment improves the efficiency of the respiratory system and normalizes the hypoxemic stimulus.

Observations of Late-Onset Exercise Oscillatory Ventilation

Exercise oscillatory ventilation (EOV) is characterized by regular waxing and waning of ventilation without apnea during exercise. In patients with heart failure (HF) development of EOV is a robust predictor of mortality. EOV is typically reported during the early stages of exercise and dissipates during the later stages of exercise. We have recently identified a cohort of diagnostically diverse patients that present EOV during the late stages of exercise. This late-onset pattern is contradictory to the common pattern of EOV, thus we termed it late-onset EOV. PURPOSE: To retrospectively analyze clinical characteristics, demographics and breathing patterns of patients who presented with late-onset EOV. METHODS: The medical records of eleven patients (6M/5F, 53±19 yrs, BMI: 29±12 kg/m2) demonstrating late-onset EOV during clinically indicated cardiopulmonary exercise testing were retrospectively analyzed. The amplitude of cycles were calculated as peak VE minus nadir VE during each cycle. The period of each cycle was calculated measuring the time from nadir to nadir. VE/VCO2 slope was calculated as (VEpeak – VErest)/(VCO2peak – VCO2rest). Late-onset EOV was defined as ≥3 amplitudes of ≥ 25% of the average VE for 3 consecutive cycles with the EOV originating ≥50% VO2 peak. RESULTS: Diagnoses included heart failure (n=6), diabetes (n=4), exercise induced arrhythmia (n=7), hypertension (n=4) and hyperlipidemia (n=4) and medications included beta-blockers (n=7), aspirin (n=6), diuretics (n=5) and statins (n=5); however, no diagnosis or medication were common across all patients. The VO2 peak was 20±7 mL/kg/min (72±28% predicted VO2peak). None of the patients demonstrated oscillatory ventilation at rest, while all of the patients exhibited EOV at >50% VO2 peak (amplitude of mean VE=44.7%, period=40.4s). VE/VCO2 slope had a positive correlation with EOV amplitude (r=0.74, p=0.01). The % predicted VO2 peak had a negative relationship with EOV period (r= -0.64, p=0.04). CONCLUSION: Our data demonstrate, in a diverse patient population, that the onset of EOV can occur during late stages of exercise and is related to metrics of exercise intolerance. No clear diagnosis or medication was common among these patients. Additional research is required to elucidate the mechanisms contributing to late-onset EOV.

Target volume and motion position evaluation of four-dimensional cone-beam CT: comparison with 4D-CT using dynamic thorax phantom

Purpose: This study evaluated the target volume (TV) definition and motion position accuracies of 4D cone-beam computed tomography (CBCT) through comparison with 4D-CT, using a dynamic thorax phantom. Methods: A dynamic thorax phantom was used to acquire 4D images with respiration motion. Targets with 20-mm diameters, motion periods of 3, 4, and 6 s, and 1D and 3D motion patterns corresponding to sin and cos6 curves were used. The TV definition was contoured on all 10 phase images via threshold segmentation on all 4D datasets. The TV union was defined as the internal target volume (ITV). The TV and ITV were compared to the theoretical TVR and ITVR. For motion position evaluation, the TV centroid positions were measured and the root mean square errors (RMSEs) of these measured positions calculated relative to the phantom setup positions. In addition, the breathing patterns of patients with lung tumor were evaluated. Results: The maximum differences in TV and ITV for 4D-CT were 0.66 cm3 and −14.03% for a cos6 motion pattern with a 3-s period, respectively. In contrast, the maximum average differences in TV and ITV for 4D-CBCT were 0.43 cm3 and −6.48%, respectively, for all motion patterns and periods. The 4D-CT and 4D-CBCT RMSEs were within 2.5 mm for most motion patterns. For patient breathing patterns, the average differences in TV, ITV, and positions between 4D-CT and 4D-CBCT were 0.18 cm3, 0.23 cm3, and 1.1 mm, respectively. Conclusions: Although 4D-CT and 4D-CBCT have differences in image acquisition and voxel size, the TV and motion position accuracies for 4D-CBCT are consistent with those of 4D-CT.

Factors Associated with Dysfunctional Breathing in Patients with Difficult to Treat Asthma

Understanding of dysfunctional breathing in patients with difficult asthma who remain symptomatic despite maximal inhaler therapy is limited. We characterized the pattern of dysfunctional breathing in patients with difficult asthma and identified possible contributory factors. Dysfunctional breathing was identified in patients with difficult asthma using the Nijmegen Questionnaire (score >23). Demographic characteristics, asthma variables, and comorbidities were assessed. Multivariate logistic regression was performed for dysfunctional breathing, adjusted for age, sex, body mass index, and airflow obstruction. Of 157 patients with difficult asthma, 73 (47%) had dysfunctional breathing. Compared with patients without dysfunctional breathing, those with dysfunctional breathing experienced poorer asthma status (symptom control, quality of life, and exacerbation rates) and greater unemployment. In addition, more frequently they had elevated sino-nasal outcome test scores, anxiety, depression, sleep apnea, and gastroesophageal reflux. On multivariate analysis, anxiety (odds ratio [OR], 3.26; 95% CI, 1.18-9.01; P= .02), depression (OR, 2.8; 95% CI, 1.14-6.9; P= .03), and 22-item sino-nasal outcome test score (OR, 1.03; 95% CI, 1.003-1.05; P= .03) were independent risk factors for dysfunctional breathing. Dysfunctional breathing is common in difficult asthma and associated with worse asthma status and unemployment. The independent association with psychological disorders and nasal obstruction highlight an important interaction between comorbid treatable traits in difficult asthma.