Inspiration Breath Research Articles

Mechanical Ventilation Redistributes Blood to Poorly Ventilated Areas in Experimental Lung Injury.

Determine the intra-tidal regional gas and blood volume distributions at different levels of atelectasis in experimental lung injury. Test the hypotheses that pulmonary aeration and blood volume matching is reduced during inspiration in the setting of minimal tidal recruitment/derecruitment and that this mismatching is an important determinant of hypoxemia. Preclinical study. Research laboratory. Seven anesthetized pigs 28.7 kg (SD, 2.1 kg). All animals received a saline-lavage surfactant depletion lung injury model. Positive end-expiratory pressure was varied between 0 and 20 cm H2O to induce different levels of atelectasis. Dynamic dual-energy CT images of a juxtadiaphragmatic slice were obtained, gas and blood volume fractions within three gravitational regions calculated and normalized to lung tissue mass (normalized gas volume and normalized blood volume, respectively). Ventilatory conditions were grouped based upon the fractional atelectatic mass in expiration (< 20%, 20-40%, and ≥ 40%). Tidal recruitment/derecruitment with fractional atelectatic mass in expiration greater than or equal to 40% was less than 7% of lung mass. In this group, inspiration-related increase in normalized gas volume was greater in the nondependent (818 µL/g [95% CI, 729-908 µL/g]) than the dependent region (149 µL/g [120-178 µL/g]). Normalized blood volume decreased in inspiration in the nondependent region (29 µL/g [12-46 µL/g]) and increased in the dependent region (39 µL/g [30-48 µL/g]). Inspiration-related changes in normalized gas volume and normalized blood volume were negatively correlated in fractional atelectatic mass in expiration greater than or equal to 40% and 20-40% groups (r = 0.56 and 0.40), but not in fractional atelectatic mass in expiration less than 20% group (r = 0.01). Both the increase in normalized blood volume in the dependent region and fractional atelectatic mass in expiration negatively correlated with PaO2/FIO2 ratio (ρ = -0.77 and -0.93, respectively). In experimental atelectasis with minimal tidal recruitment/derecruitment, mechanical inspiratory breaths redistributed blood volume away from well-ventilated areas, worsening PaO2/FIO2.

A Prospective Trial to Compare Deep Inspiratory Breath Hold With Prone Breast Irradiation

PurposeTo compare heart and lung doses for adjuvant whole breast irradiation (WBI) between radiation plans generated supine with deep inspiratory breath hold (S-DIBH) and prone with free-breathing (P-FB) and examine the effect of breast volume (BV) on dosimetric parameters. Methods and MaterialsPatients with left breast ductal carcinoma in situ or invasive cancer receiving adjuvant WBI were enrolled on a single-institutional prospective protocol. Patients were simulated S-DIBH and P-FB; plans were generated using both scans. Wilcoxon signed-rank and rank-sum tests were used to compare intrapatient differences between plans for the entire cohort and within BV groups defined by tertiles. ResultsForty patients were enrolled. Thirty-four patients are included in the analysis owing to patient withdrawal or inability to hold breath. With WBI dose of 4005 to 4256 cGy, mean heart dose (MHD) was 80 cGy in S-DIBH and 77 cGy in P-FB (P = .08). Mean ipsilateral lung dose (MLD) was 453 cGy in S-DIBH and 45 cGy in P-FB (P < .0001). Mean and max left anterior descending artery doses were 251 cGy and 551 cGy in S-DIBH, respectively (P = .1), and 324 cGy and 993 cGy in P-FB, respectively (P = .3). Hot spot and separation were 109% and 22 cm in S-DIBH, respectively, and 107% and 16 cm in P-FB, respectively (P < .0001). For patients with smallest BV, S-DIBH improved MHD and left anterior descending artery doses; for those with largest BV, P-FB improved cardiac dosimetry. With increasing BV, there was an increasing advantage of P-FB for MHD (P = .05), and max (P = .03) and mean (P = .02) left anterior descending artery doses, and the reduction in MLD, hot spot, and separation with P-FB increased (P < .05). ConclusionsMHD did not differ between P-FB and S-DIBH, whereas MLD was significantly lower with P-FB. Analysis according to breast volume revealed improved cardiac dosimetry with S-DIBH for women with smallest BV and improved cardiac dosimetry with P-FB for women with larger BV, thereby providing a dosimetric rationale for using breast size to help determine the optimal positioning for WBI.

The Impact of Tracheostomy Timing on the Duration and Complications of Mechanical Ventilation

Background: Mechanical ventilation is a life support for ICU patients and is indicated in case of acute or chronic respiratory failure. 75% of patients admitted to ICU require this support and most of them stay on prolonged MV. Tracheostomy plays a fundamental role in airway management, facilitating ventilator weaning and reducing the duration of MV. Early tracheostomy is defined when the procedure is conducted up to 10 days after the beginning of MV and late tracheostomy when the procedure is performed after this period. Controversy still exists over the ideal timing and classification of early and late tracheostomy. Objective: Evaluate the impact of timing of tracheostomy on ventilator weaning. Method: Single-center retrospective study. Patients were divided into three groups: very early tracheostomy (VETrach), intermediate (ITrach) and late (LTrach): &gt;10 days. Results: One hundred two patients were included: VETrach (n=21), ITrach (n=15), and LTrach (n=66). ITrach group had lower APACHE II (p=0.004) and SOFA (p≤0.001). Total ICU length of stay, and incidence of post-tracheostomy ventilator-associated pneumonia were significantly lower in the VETrach and ITrach groups. The GCS and RASS scores improved in all groups, while the maximal inspiratory pressure and rapid shallow breathing index showed a tendency towards improvement on discharge from the ICU. Conclusion: Very early tracheostomy did not reduce the duration of MV or length of ICU stay after the procedure when compared to late tracheostomy, but was associated with low rates of ventilatorassociated pneumonia. Neurological patients benefitted more from tracheostomy, particularly very early and intermediate tracheostomy.

Evaluating the Burstlet Theory of Inspiratory Rhythm and Pattern Generation.

The preBötzinger complex (preBötC) generates the rhythm and rudimentary motor pattern for inspiratory breathing movements. Here, we test “burstlet” theory (Kam et al., 2013a), which posits that low amplitude burstlets, subthreshold from the standpoint of inspiratory bursts, reflect the fundamental oscillator of the preBötC. In turn, a discrete suprathreshold process transforms burstlets into full amplitude inspiratory bursts that drive motor output, measurable via hypoglossal nerve (XII) discharge in vitro. We recap observations by Kam and Feldman in neonatal mouse slice preparations: field recordings from preBötC demonstrate bursts and concurrent XII motor output intermingled with lower amplitude burstlets that do not produce XII motor output. Manipulations of excitability affect the relative prevalence of bursts and burstlets and modulate their frequency. Whole-cell and photonic recordings of preBötC neurons suggest that burstlets involve inconstant subsets of rhythmogenic interneurons. We conclude that discrete rhythm- and pattern-generating mechanisms coexist in the preBötC and that burstlets reflect its fundamental rhythmogenic nature.

Does it make difference to measure diaphragm function with M mode (MM) or B mode (BM)?

Diaphragm dysfunction occurs in mechanically ventilated subjects. Recent literature suggests that diaphragm thickening fraction (DTF) measured by ultrasound can be useful to predict weaning outcome. However, there is no standardized approach in the measurement of diaphragm thickness (DT) and limited data exists comparing different measurement techniques of diaphragm thickness (M mode-MM or B mode-BM). The goal of this study was to compare MM with BM in the measurements of DT and excursion in the ICU subjects. DT measurements were obtained from the right diaphragm during tidal and maximal inspiratory breathing. Three measurements of the DT were taken both in MM and BM and their mean values were calculated. DT was measured during inspiration and expiration and DTF was calculated. Excursion of diaphragm was also measured with MM and BM during tidal and maximal inspiratory breathing. Bias and agreement between the two measurement methods were evaluated with Bland and Altman test. Sixty-two subjects were enrolled in the study. While 25 (40%) subjects were receiving invasive mechanical ventilation, 14 (23%) subjects ventilated noninvasively. There were no significant difference between the measurement results of MM and BM. BM and MM tidal diaphragm measurements during the inspiratory (0.3 ± 0.08 and 0.31 ± 0.08cm; P = 0.022), expiratory (0.24 ± 0.07 and 0.24 ± 0.07cm; P = 0.315) phases and tidal DTF were (27 ± 16 and 31 ± 14%, P = 0.089) respectively. Results of our study suggests that except tidal inspiratory diaphragm thickness, all thickness and excursion measurements with MM and BM are very compatible with each other. Further studies are necessarry to confirm our results and to standardize the measurements of diaphragm.

Mechanisms of improved exercise capacity following respiratory muscle training in athletes with cervical spinal cord injury.

Mechanisms of improved exercise capacity following respiratory muscle training in athletes with cervical spinal cord injury.

Methodology and reliability of respiratory muscle assessment

The optimal method for respiratory muscle endurance (RME) assessment remains unclear. This study assessed the test-retest reliability of two RME-test methodologies. Fifteen healthy adults attended the laboratory on four occasions, separated by 5 ± 2 days, and completed each test in a random, “one on two” order. They performed spirometry testing, maximal respiratory pressure assessment and two different RME tests: an inspiratory resistive breathing (IRB) and an isocapnic hyperpnea endurance (IHE) test. Typical error, expressed as coefficient of variation, for IRB maximal inspiratory pressure (MIP) and IHE maximal ventilation were 12.21 (8.85–19.67) % and 10.73 (7.78–17.29) %, respectively. Intraclass correlation coefficients for the same parameters were 0.83 (0.46-0.94) and 0.80 (0.41-0.93), respectively. No correlations were found between RME parameters derived from the IHE and IRB tests (all p > 0.05). Significant positive correlations were found between both IRB and IHE outcomes and spirometry parameters, MIP and maximal expiratory pressure (p < 0.05).Given these results, IRB and IHE appear to be suitable for RME testing in healthy people, although they may reflect different physiological mechanisms (respiratory mechanics and respiratory muscle capacity for IHE test vs. inspiratory muscle capacity for IRB test). Future studies are therefore warranted that compare IRB and IHE tests in clinical settings.

Improvement in Cardiac Dosimetry by Optimizing Heart-Sparing Breast Radiotherapy

Darby et al. demonstrated that cardiac events after breast radiation therapy (RT) are associated with mean heart dose (MHD). MHD is dependent on treatment fields and can be reduced by various techniques, such as deep inspiratory breath hold (DIBH), prone positioning, and cardiac blocks. The purpose of this study was to assess changes in MHD with advancements in modern RT by technique and treatment fields. This retrospective study included breast cancer patients treated from 2010 to 2018 at a single institution in an IRB approved registry. MHD was analyzed with respect to clinical variables, including laterality, cardiac sparing technique, and treatment fields, including regional nodal irradiation (RNI) with or without internal mammary nodal irradiation (IMNI). 765 patients (431 left, 315 right, 19 bilateral) were included. The average MHD was 1.87 Gy (SD 1.36 Gy, median 1.43 Gy) for left sided cases vs. 0.71 Gy (SD 0.80 Gy, median 0.51 Gy) for right sided cases (p<0.0001). Of the 43 patients that had a MHD > 4 Gy, bilateral cases were at a highest risk (21.1%), vs. left sided (7.7%) and right sided cases (1.9%) (p<0.0001). For left sided cases, average MHD without RNI, RNI without IMNI, and RNI with IMNI were 1.40 Gy (SD 0.98 Gy, median 1.16 Gy), 2.01 Gy (SD 1.15 Gy, median 1.63 Gy), and 3.48 Gy (SD 2.17 Gy, median 3.21 Gy), respectively. Following the 2013 publication of Darby et al, the average MHD significantly decreased for left sided RT cases (2.02 vs 1.82 Gy, p= 0.039) due to institutional adoption of cardiac-sparing techniques. For left sided cases w/o RNI, use of cardiac sparing techniques reduced average MHD from 1.61 Gy (SD 1.09 Gy, median 1.36 Gy) to 1.22 Gy (SD 0.99 Gy, median 0.99 Gy) with DIBH and 1.02 Gy (SD 0.56 Gy, median 0.78 Gy) with prone positioning respectively (p<0.0001), with no difference between techniques (p = 0.42). For left sided cases with RNI, DIBH reduced average MHD from 2.4 Gy (SD 0.13 Gy, median 2.02 Gy) down to 2.1 Gy (SD 1.57 Gy, median 1.6 Gy), p= 0.046. For left sided cases of RNI with IMNI, average MHD was 3.09 Gy (SD 2.38 Gy, median 2.57 Gy) with partially wide tangents compared to 3.99 Gy (SD 1.82 Gy, median 3.79 Gy) with matched electron fields (p= 0.053). For left sided cases with IMNI, the MHD was 3.48 Gy (SD 2.31 Gy, median 3.21 Gy) with DIBH compared to 3.64 Gy ( SD 2.16 Gy, median 3.37 Gy) without DIBH (p=0.27). The MHD for left sided RT with reconstruction was 1.94 Gy (SD 1.21 Gy, median 1.53 Gy) and without reconstruction was 1.85 Gy (SD 1.42 Gy, median 1.39 Gy). Cardiac doses were lower following the publication of Darby et al. Overall the average MHD was <1 Gy and <2 Gy for right and left breast cancers, respectively, by increased utilization of cardiac sparing techniques such as DIBH and prone positioning.

Evaluating improvements in cardiac dosimetry in breast radiotherapy and comparison of cardiac sparing techniques

Data from Darby et al. demonstrated that cardiac dose in patients undergoing breast radiation therapy is associated with cardiac events. Cardiac dose is primarily dependent on treatment laterality and treatment fields. More recently, techniques such deep inspiratory breath hold (DIBH) and prone positioning have been used as cardiac sparing techniques. The purpose of this study is to assess changes in cardiac dosimetry with cardiac sparing techniques. This retrospective study included breast cancer patients treated from 2010 to 2018 at a single institution. Mean heart dose (MHD) was analyzed with respect to treatment era, laterality, cardiac sparing technique, and treatment fields, including regional nodal irradiation (RNI) and internal mammary nodal irradiation (IMNI). Seven hundred sixty-five patients were included in this study. Average MHD was 1.87 Gy for left-sided cases and 0.71 Gy for right-sided cases (p < 0.0001). For left-sided cases, the average MHD without RNI, RNI without IMNI, and RNI with IMNI was 1.40 Gy, 2.01 Gy, and 3.48 Gy respectively. For left-sided cases without RNI, the average MHD decreased from 1.61 to 1.22 Gy using DIBH (p < 0.0001), and to 1.02 Gy with prone positioning (p < 0.0001). There was no difference in MHD between DIBH and prone techniques (p = 0.44). For left-sided cases with RNI, DIBH reduced the average MHD from 2.4 to 2.1 Gy (p = 0.04). Following the 2013 publication of Darby et al., the average MHD significantly decreased for left-sided RT cases (2.02 vs. 1.83 Gy, p = 0.03) due to increased institutional adoption of cardiac-sparing techniques. Cardiac doses were lower following the 2013 publication of Darby et al. due to greater use of cardiac sparing techniques. Overall, the average MHD was < 1 Gy and < 2 Gy for right and left breast cancers, respectively, with lower doses achieved using DIBH and prone positioning as cardiac sparing techniques.

Long-Distance Axon Regeneration Promotes Recovery of Diaphragmatic Respiratory Function after Spinal Cord Injury.

Compromise in inspiratory breathing following cervical spinal cord injury (SCI) is caused by damage to descending bulbospinal axons originating in the rostral ventral respiratory group (rVRG) and consequent denervation and silencing of phrenic motor neurons (PhMNs) that directly control diaphragm activation. In a rat model of high-cervical hemisection SCI, we performed systemic administration of an antagonist peptide directed against phosphatase and tensin homolog (PTEN), a central inhibitor of neuron-intrinsic axon growth potential. PTEN antagonist peptide (PAP4) robustly restored diaphragm function, as determined with electromyography (EMG) recordings in living SCI animals. PAP4 promoted substantial, long-distance regeneration of injured rVRG axons through the lesion and back toward PhMNs located throughout the C3–C5 spinal cord. These regrowing rVRG axons also formed putative excitatory synaptic connections with PhMNs, demonstrating reconnection of rVRG-PhMN-diaphragm circuitry. Lastly, re-lesion through the hemisection site completely ablated functional recovery induced by PAP4. Collectively, our findings demonstrate that axon regeneration in response to systemic PAP4 administration promoted recovery of diaphragmatic respiratory function after cervical SCI.

Self-control is linked to interoceptive inference: Craving regulation and the prediction of aversive interoceptive states induced with inspiratory breathing load

The interoceptive inference framework suggests that our brain continuously anticipates future states of our body and aims to avoid events that might counteract homeostasis by minimizing prediction errors through active inference; e.g. appropriate actions. If predicted interoceptive models are inaccurate, behavior inconsistent with our long-term homeostatic goals may result; e.g. in failures in self-control. Using a within-subject design including an inspiratory breathing-load task to examine the prediction of aversive interoceptive perturbation and a craving-regulation for palatable foods task, we examined the relationship between self-control and aversive interoceptive predictive models. Those individuals (n = 51 healthy individuals from the general population) who were more accurate in predicting their interoceptive state with respect to anticipated versus experienced dyspnea were significantly more effective in the down-regulation of craving using negative future-thinking strategies. These individuals also scored higher on a measure of trait self-control, i.e. self-regulation to achieve long-term goals. Thus, individuals with more accurate predictive interoceptive models are better able to modulate cravings and thus exert better self-control.

Deep Inspiratory Breath Hold Technique to Reduce Cardiotoxicity when Delivering Left Breast/Internal Mammary Chain Radical Radiotherapy: Obstacles to Compliance

Deep Inspiratory Breath Hold Technique to Reduce Cardiotoxicity when Delivering Left Breast/Internal Mammary Chain Radical Radiotherapy: Obstacles to Compliance

Design of a Metered-Dose Inhaler Actuated by Shape Memory Alloy

The global prevalence of asthma and chronic obstructive pulmonary disease (COPD) is on the order of hundreds of millions of individuals. The most common treatment approach is to take a self-administered inhaled medication. This study focuses on pressurized metered-dose inhalers (MDIs) where, unfortunately, rates of mishandling and misuse are extremely high and lead to improper treatment. One significant challenge results from the timing miscoordination of the medicine dispersion and inhalation breath. To address this, this study demonstrates the feasibility of automating the timing of the medicine dispersion by integrating a shape memory alloy (SMA) actuator and a differential pressure sensor into the casing of a traditional MDI. The approach is to measure the vacuum pressure created by an inspiratory breath, evaluate criteria indicating an acceptable breath, and if those criteria are met, heat the SMA actuator to depress the cartridge and disperse medicine. To meet actuation requirements and reliably depress the inhaler cartridge, two concepts for configuring an SMA wire were designed and compared with respect to complexity, actuation timing, and energy consumption. The proposed concept was able to disperse medicine in 263 ms, averaged over 100 actuations on a single battery charge, facilitating the early dispersion of medicine during an inhalation breath. By describing the design process of an SMA-actuated MDI that does not result in a significant increase of its weight or size, this study provides a practical technological approach for reducing the improper treatment of asthma and COPD due to timing miscoordination.

Effect of an Incentive Spirometer Patient Reminder After Coronary Artery Bypass Grafting

Incentive spirometers (ISs) were developed to reduce atelectasis and are in widespread clinical use. However, without IS use adherence data, the effectiveness of IS cannot be determined. To evaluate the effect of a use-tracking IS reminder on patient adherence and clinical outcomes following coronary artery bypass grafting (CABG) surgery. This randomized clinical trial was conducted from June 5, 2017, to December 29, 2017, at a tertiary referral teaching hospital and included 212 patients who underwent CABG, of whom 160 participants were randomized (intent to treat), with 145 completing the study per protocol. Participants were stratified by surgical urgency (elective vs nonelective) and sex (men vs women). A use-tracking, IS add-on device (SpiroTimer) with an integrated use reminder bell recorded and timestamped participants' inspiratory breaths. Patients were randomized by hourly reminder "bell on" (experimental group) or "bell off" (control group). Incentive spirometer use was recorded for the entire postoperative stay and compared between groups. Radiographic atelectasis severity (score, 0-10) was the primary clinical outcome. Secondary respiratory and nonrespiratory outcomes were also evaluated. A total of 145 per-protocol participants (112 men [77%]; mean age, 69 years [95% CI, 67-70]; 90 [62%] undergoing a nonelective procedure) were evaluated, with 74 (51.0%) in the bell off group and 71 (49.0%) in the bell on group. The baseline medical and motivation-to-recover characteristics of the 2 groups were similar. The mean number of daily inspiratory breaths was greater in bell on (35; 95% CI, 29-43 vs 17; 95% CI, 13-23; P < .001). The percentage of recorded hours with an inspiratory breath event was greater in bell on (58%; 95% CI, 51-65 vs 28%; 95% CI, 23-32; P < .001). Despite no differences in the first postoperative chest radiograph mean atelectasis severity scores (2.3; 95% CI, 2.0-2.6 vs 2.4; 95% CI, 2.2-2.7; P = .48), the mean atelectasis severity scores for the final chest radiographs conducted before discharge were significantly lower for bell on than bell off group (1.5; 95% CI, 1.3-1.8 vs 1.8; 95% CI, 1.6-2.1; P = .04). Of those with early postoperative fevers, fever duration was shorter for bell on (3.2 hours; 95% CI, 2.3-4.6 vs 5.2 hours; 95% CI, 3.9-7.0; P = .04). Having the bell turned on reduced noninvasive positive pressure ventilation use rates (37.2%; 95% CI, 24.1%-52.5% vs 19.2%; 95% CI, 10.2%-33.0%; P = .03) for participants undergoing nonelective procedures. Bell on reduced the median postoperative length of stay (7 days; 95% CI, 6-9 vs 6 days; 95% CI, 6-7; P = .048) and the intensive care unit length of stay for patients undergoing nonelective procedures (4 days; 95% CI, 3-5 vs 3 days; 95% CI, 3-4; P = .02). At 6 months, the bell off mortality rate was higher than bell on (9% vs 0%, P = .048) for participants undergoing nonelective procedures. The incentive spirometer reminder improved patient adherence, atelectasis severity, early postoperative fever duration, noninvasive positive pressure ventilation use, ICU and length of stay, and 6-month mortality in certain patients. With the reminder, IS appears to be clinically effective when used appropriately. ClinicalTrials.gov identifier: NCT02952027.

ANALYTICAL MANUAL TRAINING TECHNIQUES FOR M. SERRATUS ANTERIOR

In manual healing massage techniques and kinesitherapy analytical exercises, there is no complete information on the targeted effects on separate parts of the m.serratus anterior. It is a protractor, a blade abductor, a helping muscle in the inspiratory breathing movements and participates in the training of the pectoral muscles. Its complex function defines it as muscle, which should be emphasized in shoulder girdle disease, postural abnormalities, pulmonary diseases, peripheral nerve damage, etc. Based on a study of the various techniques available for stretching, healing massage and analytical training, we offer a complex impact on m.serratus anterior. To perform the techniques, we use a tool to work on the muscles around the blade. М..serratus anterior has three parts: m.serattus anterior superior, m.serratus anterior intermedius et inferior. The fibers of the lower part are directed medial-caudal position, the fibers of the middle part are located more horizontally and the upper part moves in the medial direction towards the collarbone. The location of the individual parts and fibers helps to target the muscle. The healing massage methodology includes the following techniques: crunching is available for the serratus anterior muscle. For its crushing, the patient is in a lateral lying position, his arm is lifted and placed behind the head that opens the axillary well. The masseur is behind the patient's back. The well-defined muscles are treated with a pinching technique. In poorly expressed hypotrophic muscles, it is crushed by pressure on the ribs with the cushions of the spread fingers in the intercostal area. The innervation of the muscles starts with roots С5,6,7 , n.thoracicus longus which ends in the axilla under the medial third of v.axillaris and goes down along the serratum anterior muscle of the chest. To perform a therapeutic effect on the individual parts of the muscle, we instruct the patient to perform analytical exercises at the same time and then perform an autostretching at the time the therapist uses the muscle-processing tool. We urge the patient to perform inspiration to activate muscle function. Inspiratory muscle training is used to better strengthen the muscle.

Altered anticipation and processing of aversive interoceptive experience among women remitted from bulimia nervosa.

Bulimia nervosa (BN) is characterized by dysregulated intake of food, which may indicate homeostatic imbalance. Critically important for homeostatic regulation is interoception, or the sensing and processing of body-relevant information. A well-documented link between avoidance of unpleasant body sensations and BN symptoms suggests that aversive interoceptive experiences may be particularly relevant to BN pathophysiology. This study examined whether individuals with a history of BN showaberrant neural processing of aversive interoceptive stimuli. Using a cued inspiratory breathing load paradigm, we compared women remitted from BN (RBN; n = 24; to reduce the confounding effects of active bulimic symptoms) and control women (CW; n = 25). During breathing load anticipation, the RBN group, relative to CW, showed increased activation in mid-insula, superior frontal gyrus, putamen, dorsal anterior cingulate, posterior cingulate, and amygdala. However, over the course of the aversive experience, neural activation in RBN relative to CW showed an aberrant decline in most of these regions. Exploratory analyses indicated that greater activation during breathing load anticipation was associated with past bulimic symptom severity and the duration of symptom remission. An exaggerated anticipatory response and an abnormally decreasing response during aversive homeostatic perturbations may promote hallmark bulimic behaviors-binge eating, dietary restriction, and purging. Our findings support a role for homeostatic instability in BN, and these altered patterns of brainactivation may serve as novel targets for pharmacological, neuromodulatory, and behavioral interventions.

Within-breath changes in respiratory system impedance in children with cystic fibrosis.

The aim of this study was to assess within-breath respiratory system impedance by the forced oscillation technique (FOT) in children with cystic fibrosis (CF) and relate it to the underlying lung disease. Thirty-three children with CF (median [range] age 12.0 [6-17] years) underwent FOT at 8 Hz during tidal breathing, multiple breath nitrogen washout (LCI), spirometry (FEV1), body plethysmography (RV/TLC), and magnetic resonance imaging (MRI). FOT outcomes included: mean inspiratory, expiratory, and whole breath resistance (R8INSP , R8EXP , R8TOT ) and reactance (X8INSP , X8EXP , X8TOT ), and the differences between X8INSP and X8EXP (ΔX8). Morphological changes were evaluated by MRI using CF-specific morphological scores. Spearman correlation was performed to examine the correlation between FOT indices and other parameters. FEV1 was negatively correlated with R8EXP (r = -0.52, P = 0.002) and ΔX8 (r = -0.55, P = 0.001), and positively correlated with and X8EXP (r = 0.56, P < 0.001). RV/TLC was positively correlated with R8EXP (r = 0.43, P = 0.013), and ΔX8 (r = 0.54, P = 0.001) and negatively correlated with X8EXP (r = -0.54, P = 0.001). We found poor correlation between FOT parameters and LCI and no correlation between FOT parameters and MRI scores. In children with CF, changes in within-breath FOT parameters are consistent with peripheral obstruction and dynamic airway compression, while they are not associated with ventilation heterogeneities and morphological alterations.

Trpm4 ion channels in pre-Bötzinger complex interneurons are essential for breathing motor pattern but not rhythm.

Inspiratory breathing movements depend on pre-Bötzinger complex (preBötC) interneurons that express calcium (Ca2+)-activated nonselective cationic current (ICAN) to generate robust neural bursts. Hypothesized to be rhythmogenic, reducing ICAN is predicted to slow down or stop breathing; its contributions to motor pattern would be reflected in the magnitude of movements (output). We tested the role(s) of ICAN using reverse genetic techniques to diminish its putative ion channels Trpm4 or Trpc3 in preBötC neurons in vivo. Adult mice transduced with Trpm4-targeted short hairpin RNA (shRNA) progressively decreased the tidal volume of breaths yet surprisingly increased breathing frequency, often followed by gasping and fatal respiratory failure. Mice transduced with Trpc3-targeted shRNA survived with no changes in breathing. Patch-clamp and field recordings from the preBötC in mouse slices also showed an increase in the frequency and a decrease in the magnitude of preBötC neural bursts in the presence of Trpm4 antagonist 9-phenanthrol, whereas the Trpc3 antagonist pyrazole-3 (pyr-3) showed inconsistent effects on magnitude and no effect on frequency. These data suggest that Trpm4 mediates ICAN, whose influence on frequency contradicts a direct role in rhythm generation. We conclude that Trpm4-mediated ICAN is indispensable for motor output but not the rhythmogenic core mechanism of the breathing central pattern generator.

Inspiratory muscle training improves performance of a repeated sprints ability test in professional soccer players

BackgroundInspiratory muscle training (IMT) is an important method of attenuating both respiratory and peripheral effort perceptions, consequently improving neuromuscular performance and resulting in greater improvements in exercise capacity than exercise training alone. ObjectiveThe aim of this study was to investigate the effects of IMT on exercise tolerance, repeated sprint ability (RSA) performance, maximal inspiratory pressure (MIP), and peak inspiratory flow (PIF) in a cohort of professional male soccer players. MethodsTwenty-two healthy male professional soccer players (18.3 ± 1.4 years; 174.5 ± 6.1 cm; 70.5 kg ± 4.6 kg; body fat 10.1 ± 4.2%) from a club in the Brazilian first division soccer league participated in this study. IMT consisted of 15 and 30 self-paced inspiratory breaths (each to 50% maximal static inspiratory pressure [P0]) in the 1-and 2-week intervention period, respectively. IMT was performed prior to soccer training (1 sets.d−1; 6 d.wk−1) with repeated sprint ability (RSA) assessed pre- and post- the 2-week period of IMT. ResultsStatistical analyses identified a significant (p < 0.001) decrease in sprint time post-IMT. Additionally, RSAbest, RSAmean, total sprint time and percentage of RSA performance decrement (RSA % dec) also showed significant decreases (p < 0.0001) post-IMT. Additional measures including MIP and PIF were also significantly elevated (p < 0.0002) following the 2-week period of IMT. ConclusionIn conclusion, our results raise two important issues. Firstly, IMT demonstrated enhanced inspiratory muscle strength in professional soccer players. Secondly, this increase in inspiratory muscle efficiency led to a decrease in sprint time and improved exercise tolerance. We recommend that a standard training protocol be developed and tested in an experimental and control group with a large representative sample.

Effect of Inspiratory Muscle Training and Diaphragmatic Breathing Exercises on Dyspnea, Pulmonary Functions, Fatigue and Functional Capacity in Pregnancy during Third Trimester

Effect of Inspiratory Muscle Training and Diaphragmatic Breathing Exercises on Dyspnea, Pulmonary Functions, Fatigue and Functional Capacity in Pregnancy during Third Trimester