Central and peripheral mechanisms underlying respiratory deficits in a mouse model of accelerated senescence.

Aging invariably decreases sensory and motor stimuli and affects several neuronal systems and their connectivity to key brain regions, including those involved in breathing. Nevertheless, further investigation is needed to fully comprehend the link between senescence and respiratory function. Here, we investigate whether a mouse model of accelerated senescence could develop central and peripheral respiratory abnormalities. Adult male Senescence Accelerated Mouse Prone 8 (SAMP8) and the control SAMR1 mice (10 months old) were used. Ventilatory parameters were assessed by whole-body plethysmography, and measurements of respiratory input impedance were performed. SAMP8 mice exhibited a reduction in the density of neurokinin-1 receptor immunoreactivity in the entire ventral respiratory column. Physiological experiments showed that SAMP8 mice exhibited a decreased tachypneic response to hypoxia (FiO2 = 0.08; 10 min) or hypercapnia (FiCO2 = 0.07; 10 min). Additionally, the ventilatory response to hypercapnia increased further due to higher tidal volume. Measurements of respiratory mechanics in SAMP8 mice showed decreased static compliance (Cstat), inspiratory capacity (IC), resistance (Rn), and elastance (H) at different ages (3, 6, and 10 months old). SAMP8 mice also have a decrease in contractile response to methacholine compared to SAMR1. In conclusion, our findings indicate that SAMP8 mice display a loss of the NK1-expressing neurons in the respiratory brainstem centers, along with impairments in both central and peripheral respiratory mechanisms. These observations suggest a potential impact on breathing in a senescence animal model.

Nucleus of the solitary tract neuronal degeneration and impaired hypoxia response in a model of Parkinson's disease.

Parkinson's disease (PD) involves the degeneration of dopaminergic neurons in the substantia nigra (SNpc) and manifests with both classic and non-classic motor symptoms, including respiratory failure. Our study aims to investigate the involvement of the commissural and intermediate nucleus of the solitary tract (cNTS and iNTS) in the attenuated respiratory response to hypoxia in PD. Using a PD rat model induced by bilateral injection of 6-hydroxydopamine (6-OHDA) into the striatum of male Wistar rats, we explored potential alterations in the population of Phox2b neurons or hypoxia-activated neurons in the NTS projecting to the retrotrapezoid nucleus (RTN). Additionally, we explored neuronal connectivity between SNpc and cNTS. Projections pathways were assessed using unilateral injection of the retrograde tracer Fluorogold (FG) in the cNTS and RTN. Neuronal activation was evaluated by analyzing fos expression in rats exposed to hypoxia. In the PD model, the ventilatory response, measured through whole-body plethysmography, was impaired at both baseline and in response to hypoxia. A reduction in Phox2b-expressing neurons or hypoxia-activated neurons projecting to the RTN was observed. Additionally, we identified an indirect pathway linking the SNpc and cNTS, which passes through the periaqueductal gray (PAG). In conclusion, our findings suggest impairment in the SNpc-PAG-cNTS pathway in the PD model, explaining the loss of Phox2b-expressing neurons or hypoxia-activated neurons in the cNTS and subsequent respiratory impairment during hypoxic stimulation. We propose that the reduced population of Phox2b-expressing neurons in the NTS may include the same neurons activated by hypoxia and projecting to the RTN.

The pontine Kölliker-Fuse nucleus is important for reduced postinspiratory airflow elicited by stimulation of the ventral respiratory parafacial region.

Considering that the retrotrapezoid nucleus/respiratory parafacial region (RTN/pFRG) would be an important center in the central nervous system involved in the maintenance and modulation of respiratory activity, we hypothesized that neurons in this nucleus would also be involved in the postinspiratory (post-I) phase of the respiratory cycle through a connection with the pontine Kölliker-Fuse (KF) region. Here, we performed pharmacogenetic manipulation (AAV-hM3D(Gq)-mCherry or AAV-hM4D(Gi)-mCherry) in VGlut2-cre, Ai6 conscious mice to evaluate breathing parameters through whole body plethysmography under baseline conditions (normoxia: [Formula: see text] = 0.21) or under hypercapnia or hypoxia challenges ([Formula: see text] = 0.07 or [Formula: see text] = 0.08). Under normoxia, selective stimulation of RTN/pFRG resulted in a smaller increase in V̇e (1,272 ± 102.5, vs. RTN/pFRG stimulation: 1,878 ± 122.1 mL/kg/min), due to a smaller increase in VT (5.4 ± 0.35, vs. RTN/pFRG stimulation: 7.77 ± 0.21 mL/kg) without changing fR in a condition of KF inhibition. However, inhibition of the VGlut2 neurons in the KF did affect the TE1 produced by selective activation of RTN/pFRG (119.9 ± 2.53, vs. RTN/pFRG stimulation: 104 ± 2.46 ms). Both the hypercapnia and hypoxia ventilatory response were reduced after inhibition of VGlut2-expressing KF neurons. Therefore, consistent with anatomical projections RTN/pFRG neurons regulate lung ventilation by controlling all aspects of breathing, i.e., breathing frequency, inspiration, postinspiration, and active expiration. All the modulation seems to be dependent on the integrity of the glutamatergic neurons in the KF region.NEW & NOTEWORTHY Our research reveals specific roles and interactions between the retrotrapezoid nucleus/respiratory parafacial region (RTN/pFRG) and the pontine Kölliker-Fuse (KF) region in controlling respiratory phases. RTN/pFRG neurons are key in regulating all aspects of breathing, including frequency, inspiration, postinspiration, and active expiration. This regulation depends on the functional integrity of glutamatergic neurons in the KF region, aligning with anatomical projections.

Sleep-related bruxism, microarousals and oxyhaemoglobin desaturations in sleep stages: A cross-sectional study in a large apnoeic population.

BACKGROUND: Sleep-related bruxism (SB) is the habit of grinding or clenching the teeth during sleep, mediated by the non-peripheral central nervous system. PURPOSE: The objectives of this cross-sectional study were to evaluate associations between SB, microarousals and oxyhaemoglobin desaturations and to compare the frequency of SB and microarousals in sleep stages, in an apnoeic population. METHODS: Two hundred and forty individuals composed the sample, who underwent a single full-night polysomnography. Self-reports and clinical inspections were not considered for assessing SB. The polysomnographic assessment of SB was performed using electrodes placed on masseter muscles and chin. SB was defined as more than two events of rhythmic masticatory muscle activity per hour of sleep. Microarousals were considered when there were abrupt changes in electroencephalogram frequencies, without complete awakening, lasting from 3 to 15 s. Oxyhaemoglobin desaturations were defined as significant drops (≥3%) in basal oxygen saturations. With these data, SB, microarousals and oxyhaemoglobin desaturations were evaluated and submitted to statistical analysis. RESULTS: Statistically significant differences were observed between bruxers and non-bruxers when comparing the rates of microarousals (p < .001) and oxyhaemoglobin desaturations (p = .038). There was a higher number of SB and microarousals in NREM (non-rapid eye movement) two sleep stage (p < 0.001). Bruxers had a greater risk of higher numbers of microarousals (OR = 1.023; p = .003), which did not occur for oxyhaemoglobin desaturations (OR = 0.998; p = .741). CONCLUSIONS: A higher number of microarousals presents relationship with SB; associations between SB and oxyhaemoglobin desaturations remained inconclusive; higher frequency of SB and microarousals was observed in NREM 2 sleep stage.

Baroreflex and chemoreflex interaction in high-altitude exposure: possible role on exercise performance.

The hypoxic chemoreflex and the arterial baroreflex are implicated in the ventilatory response to exercise. It is well known that long-term exercise training increases parasympathetic and decreases sympathetic tone, both processes influenced by the arterial baroreflex and hypoxic chemoreflex function. Hypobaric hypoxia (i.e., high altitude [HA]) markedly reduces exercise capacity associated with autonomic reflexes. Indeed, a reduced exercise capacity has been found, paralleled by a baroreflex-related parasympathetic withdrawal and a pronounced chemoreflex potentiation. Additionally, it is well known that the baroreflex and chemoreflex interact, and during activation by hypoxia, the chemoreflex is predominant over the baroreflex. Thus, the baroreflex function impairment may likely facilitate the exercise deterioration through the reduction of parasympathetic tone following acute HA exposure, secondary to the chemoreflex activation. Therefore, the main goal of this review is to describe the main physiological mechanisms controlling baro- and chemoreflex function and their role in exercise capacity during HA exposure.

Locus coeruleus noradrenaline depletion and its differential impact on CO2-induced panic and hyperventilation in male and female mice.

CO2 exposure has been used to investigate the panicogenic response in patients with panic disorder. These patients are more sensitive to CO2, and more likely to experience the "false suffocation alarm" which triggers panic attacks. Imbalances in locus coeruleus noradrenergic (LC-NA) neurotransmission are responsible for psychiatric disorders, including panic disorder. These neurons are sensitive to changes in CO2/pH. Therefore, we investigated if LC-NA neurons are differentially activated after severe hypercapnia in mice. Further, we evaluated the participation of LC-NA neurons in ventilatory and panic-like escape responses induced by 20% CO2 in male and female wild type mice and two mouse models of altered LC-NA synthesis. Hypercapnia activates the LC-NA neurons, with males presenting a heightened level of activation. Mutant males lacking or with reduced LC-NA synthesis showed hypoventilation, while animals lacking LC noradrenaline present an increased metabolic rate compared to wild type in normocapnia. When exposed to CO2, males lacking LC noradrenaline showed a lower respiratory frequency compared to control animals. On the other hand, females lacking LC noradrenaline presented a higher tidal volume. Nevertheless, no change in ventilation was observed in either sex. CO2 evoked an active escape response. Mice lacking LC noradrenaline had a blunted jumping response and an increased freezing duration compared to the other groups. They also presented fewer racing episodes compared to wild type animals, but not different from mice with reduced LC noradrenaline. These findings suggest that LC-NA has an important role in ventilatory and panic-like escape responses elicited by CO2 exposure in mice.

Presentation of the ATLETAS DA VOZ™ Conditioning Program

Objectives: To present a simple form of vocal and breathing conditioning for voice professionals based on concepts from vocal science. The vocal conditioning program called Voice Athletes Conditioning uses the principles of exercise physiology to gradually improve vocal and respiratory overload to achieve endurance, power, and flexibility. Methods: Due to our personal experience with high voice users, we synthesized a vocal conditioning program (AVCP) that combines voice science, exercise physiology, sports science and physical therapy principles. This is an 8-week program of daily vocal and breathing exercises with overload enhancement each week using different types of breathing devices and semi-occluded vocal tract exercises, designed and developed according to the specific requirements and performance of the voice professional. Reflections: Professional voice users often experience episodes of vocal fatigue that can directly affect their performance and vocal health. As with physical training for athletes, voice exercises can also contribute to improving vocal conditioning, preventing voice disorders, as well as helping to obtain better performance, greater tolerance to fatigue and shorter recovery time. Conclusions: AVCP is an approach that considers the principles of muscle training aimed objectively at the respiratory and vocal muscles, carried out with a variety of breathing devices and specific vocal exercises in search of greater performance time, less physiological stress, and shorter recovery time in the professional use of the voice.

Objetivos: Presentar una forma sencilla de acondicionamiento vocal y respiratorio para profesionales de la voz, basada en conceptos de la ciencia vocal. El programa de acondicionamiento vocal denominado Voice Athletes Conditioning utiliza los principios de la fisiología del ejercicio para mejorar gradualmente la sobrecarga vocal y respiratoria, con el fin de lograr resistencia, potencia y flexibilidad. Métodos: Debido a nuestra experiencia personal con usuarios de voz aguda, sintetizamos un programa de acondicionamiento vocal (AVCP) que combina principios de la ciencia de la voz, la fisiología del ejercicio, las ciencias del deporte y la fisioterapia. Se trata de un programa de 8 semanas de ejercicios vocales y respiratorios diarios con realce de sobrecarga cada semana utilizando diferentes tipos de dispositivos respiratorios y ejercicios semioclusivos del tracto vocal, diseñado y desarrollado de acuerdo con los requerimientos específicos y el rendimiento del profesional de la voz. Reflexiones: Los usuarios profesionales de la voz experimentan a menudo episodios de fatiga vocal que pueden afectar directamente su rendimiento y salud vocal. Al igual que ocurre con el entrenamiento físico de los deportistas, los ejercicios vocales también pueden contribuir a mejorar el acondicionamiento vocal, prevenir trastornos de la voz, además de ayudar a obtener un mejor rendimiento, una mayor tolerancia a la fatiga y un menor tiempo de recuperación. Conclusiones: El AVCP es un enfoque que considera los principios del entrenamiento muscular dirigido objetivamente a la musculatura respiratoria y vocal, realizado con diversos aparatos respiratorios y ejercicios vocales específicos en busca de un mayor tiempo de actuación, menor estrés fisiológico y menor tiempo de recuperación en el uso profesional de la voz.

Association of clinical indicators in TMJ, craniofacial, occlusal, and upper airway changes with symptoms of pediatric obstructive sleep apnea and mouth-breathing.

OBJECTIVE: To assess the association between self-reported symptoms of pediatric OSA and clinical signs in MB children. METHODS: Seventy-three MB children aged 7-14 years answered an interview questionnaire on OSA symptoms in childhood, focusing on chewing, nasal, and sleep disturbances. MB children were checked for changes on the craniofacial, occlusion, TMJ, upper airway, and body posture by a multi-disciplinary team, consisting of medical residents, dental, and psychology postgraduate students. Multiple logistic regression analysis verified the association between clinical signs and self-reported symptoms. RESULTS: Reported symptoms of chewing disturbance as TMD noise, muscle pain, and morning headache were significantly associated with the presence of lip incompetence and Class II malocclusion. Sleep disturbances as snoring, waking up at night, daytime sleepiness, and sleeping with the mouth open were significantly associated with the presence of hypertrophic tonsils and obstructive Mallampati score. CONCLUSION: Symptoms of pediatric OSA were found in mouth-breathing children, which should be carefully investigated in order to prevent OSA in the future.

Reducing Airway Occlusion Time Without Losing Accuracy to Predict Successful Mechanical Ventilator Liberation During the Measurement of the Timed Inspiratory Effort Index.

BACKGROUND: In 2013, a new predictor of successful mechanical ventilation liberation named timed inspiratory effort (TIE) index was devised with the normalization of the maximum inspiratory pressure (obtained within 60 s of unidirectional airway occlusion) with the time at which the value was reached. The aim of this study was to verify whether the presence of a sequence of a certain number of inspiratory effort values between 30-60 s > 1.0 cm H2O/s could predict weaning success in a performance comparable to the TIE index. METHODS: This was a retrospective observational study using 4 databases of previous studies on the TIE index. All patients receiving mechanical ventilation for ≤ 24 h were eligible. Liberation from mechanical ventilation-extubation decisions was made based on performance with spontaneous breathing trials. P < .05 was considered significant. The performance of the TIE index was evaluated by calculating the area under the receiver operating characteristics (AUROC) curve. RESULTS: From 349 eligible patients, 165 subjects were selected for analysis. The AUROC for the TIE index in the studied sample was 0.92 (95% CI 0.87-0.97, P < .001). A sequence of ≤ 4 inspiratory efforts > 1.0 cm H2O/s was found in 51.5% of the subjects, with successful ventilatory liberation occurring in 95.3%. The highest specificity values belonged to the sequence of ≤ 4 and ≤ 5 inspiratory efforts > 1.0 cm H2O/s; the highest positive predictive value and positive likelihood ratio belonged to the sequence of ≤ 4 inspiratory efforts > 1.0 cm H2O/s. The mean time that could have been spared if the procedure were interrupted after the first sequence of 4 inspiratory efforts > 1.0 cm H2O/s was 23 ± 3 s. CONCLUSIONS: The presence of a sequence of ≤ 4 inspiratory efforts > 1.0 cm H2O/s during the TIE index measurement was a reliable predictor of weaning success, which could allow timely interruption of the procedure and entail a substantial reduction in airway occlusion time.

Fluid Responsiveness Is Associated with Successful Weaning after Liver Transplant Surgery.

A positive fluid balance may evolve to fluid overload and associate with organ dysfunctions, weaning difficulties, and increased mortality in ICU patients. We explored whether individualized fluid management, assessing fluid responsiveness via a passive leg-raising maneuver (PLR) before a spontaneous breathing trial (SBT), is associated with less extubation failure in ventilated patients with a high fluid balance admitted to the ICU after liver transplantation (LT). We recruited 15 LT patients in 2023. Their postoperative fluid balance was +4476 {3697, 5722} mL. PLR maneuvers were conducted upon ICU admission (T1) and pre SBT (T2). Cardiac index (CI) changes were recorded before and after each SBT (T3). Seven patients were fluid-responsive at T1, and twelve were responsive at T2. No significant differences occurred in hemodynamic, respiratory, and perfusion parameters between the fluid-responsive and fluid-unresponsive patients at any time. Fluid-responsive patients at T1 and T2 increased their CI during SBT from 3.1 {2.8, 3.7} to 3.7 {3.4, 4.1} mL/min/m2 (p = 0.045). All fluid-responsive patients at T2 were extubated after the SBTs and consolidated extubation. Two out of three of the fluid-unresponsive patients experienced weaning difficulties. We concluded that fluid-responsive patients post LT may start weaning earlier and achieve successful extubation despite a high postoperative fluid balance. This highlights the profound impact of personalized assessments of cardiovascular state on critical surgical patients.

Exercise-induced potentiation of the acute hypoxic ventilatory response: Neural mechanisms and implications for cerebral blood flow.

A given dose of hypoxia causes a greater increase in pulmonary ventilation during physical exercise than during rest, representing an exercise-induced potentiation of the acute hypoxic ventilatory response (HVR). This phenomenon occurs independently from hypoxic blood entering the contracting skeletal muscle circulation or metabolic byproducts leaving skeletal muscles, supporting the contention that neural mechanisms per se can mediate the HVR when humoral mechanisms are not at play. However, multiple neural mechanisms might be interacting intricately. First, we discuss the neural mechanisms involved in the ventilatory response to hypoxic exercise and their potential interactions. Current evidence does not support an interaction between the carotid chemoreflex and central command. In contrast, findings from some studies support synergistic interactions between the carotid chemoreflex and the muscle mechano- and metaboreflexes. Second, we propose hypotheses about potential mechanisms underlying neural interactions, including spatial and temporal summation of afferent signals into the medulla, short-term potentiation and sympathetically induced activation of the carotid chemoreceptors. Lastly, we ponder how exercise-induced potentiation of the HVR results in hyperventilation-induced hypocapnia, which influences cerebral blood flow regulation, with multifaceted potential consequences, including deleterious (increased central fatigue and impaired cognitive performance), inert (unchanged exercise) and beneficial effects (protection against excessive cerebral perfusion).

Prevalences of sleep-related breathing disorders and severity factors in chronic spinal cord injury and abled-bodied individuals undergoing rehabilitation: a comparative study.

STUDY OBJECTIVES: The objective of this study was to discern distinguishing characteristics of sleep-related breathing disorders in individuals with chronic spinal cord injury (CSCI) compared with participants without CSCI. Additionally, the study investigated factors associated with sleep-related breathing disorder severity. METHODS: This is a cross-sectional analysis of 123 individuals without CSCI, 40 tetraplegics, and 48 paraplegics who underwent attended or partially supervised full polysomnography for suspected sleep-related breathing disorders in a rehabilitation center. Polysomnographic, transcutaneous capnography, and clinical data were collected and compared between the groups. RESULTS: Among tetraplegics, apnea-hypopnea index ≥ 30 events/h (67.5%, P = .003), central apnea (17.5%, P = .007), and higher oxygen desaturation index (80.0%, P = .01) prevailed. Sleep-related hypoventilation was present in 15.4% of tetraplegics and 15.8% of paraplegics, compared with 3.2% in participants without CSCI (P = .05). In the group without CSCI and the paraplegic group, snoring and neck circumference were positively correlated with obstructive sleep apnea (OSA) severity. A positive correlation between waist circumference and OSA severity was identified in all groups, and multivariate logistic regression analysis showed that loud snoring and waist circumference had the greatest impact on OSA severity. CONCLUSIONS: Severe OSA and central sleep apnea prevailed in tetraplegic participants. Sleep-related hypoventilation was more common in tetraplegics and paraplegics than in participants without CSCI. Loud snoring and waist circumference had an impact on OSA severity in all groups. We recommend the routine implementation of transcutaneous capnography in individuals with CSCI. We underscore the significance of conducting a comprehensive sleep assessment in the rehabilitation process for individuals with CSCI. CITATION: Souza Bastos P, Amaral TLD, Yehia HC, Tavares A. Prevalences of sleep-related breathing disorders and severity factors in chronic spinal cord injury and abled-bodied individuals undergoing rehabilitation: a comparative study. J Clin Sleep Med. 2024;20(7):1119-1129.

Respiratory activity during seizures induced by pentylenetetrazole.

This study investigated the respiratory activity in adult Wistar rats across different behavioral seizure severity induced by pentylenetetrazole (PTZ). Animals underwent surgery for electrodes implantation, allowing simultaneous EEG and diaphragm EMG (DIAEMG) recordings and the respiratory frequency and DIAEMG amplitude were measured. Seizures were acutely induced through PTZ injection and classified based on a pre-established score, with absence-like seizures (spike wave discharge (SWD) events on EEG) representing the lowest score. The respiratory activity was grouped into the different seizure severities. During absence-like and myoclonic jerk seizures, the breathing frequency decreased significantly (∼50% decrease) compared to pre- and post-ictal periods. Pronounced changes occurred with more severe seizures (clonic and tonic) with periods of apnea, especially during tonic seizures. Apnea duration was significantly higher in tonic compared to clonic seizures. Notably, during PTZ-induced tonic seizures the apnea events were marked by tonic DIAEMG contraction (tonic-phase apnea). In the majority of animals (5 out of 7) this was a fatal event in which the seizure-induced respiratory arrest preceded the asystole. In conclusion, we provide an assessment of the respiratory activity in the PTZ-induced acute seizures and showed that breathing dysfunction is more pronounced in seizures with higher severity.

Evaluation of a short in-person and online antenatal educational intervention for high-risk pregnant women linked to antenatal consultation.

INTRODUCTION: The aim of this study was to evaluate a short educational intervention that focused on labor pain (through visual analogue scale, VAS), postpartum anxiety, and birthing experience before and during the SARS-CoV-2 (COVID-19) pandemic. METHODS: This was a quasi-experimental study conducted between November 2019 and May 2021 in Brazil in 100 women with a high-risk pregnancy in the third trimester of pregnancy with an intervention group with in-person or virtual sessions (during the COVID-19 pandemic) and a non-intervention group. The antenatal intervention included breathing and relaxation techniques, upright positions, and information about labor. For evaluation, an antenatal questionnaire, State-Trait Anxiety Inventory (STAI) and a postpartum questionnaire were used. For data analysis, Student's t-test, chi-squared and Fisher's exact tests, ANOVA, bivariate, and multivariate regression analysis, were used. RESULTS: When comparing the women in the intervention group to the non-intervention group, it was observed that the latter group reported higher fear of pain at labor during antenatal consultations (p<0.013); more women needed analgesia at 0-4 cm dilation (17/40) (p<0.018); the duration of labor was ≥12 hours (37/50) (p<0.037); while the intervention reported having a regular, good or excellent labor period (36/50) (p=0.014). The multiple regression analysis for labor pain showed a significant relationship between mode of delivery (cesarean delivery: RR; SE -21.43; 5.32, p<0.001) and labor pain, and good satisfaction with labor (RR; SE -13.86; 6.40, p=0.033). CONCLUSIONS: Women from the intervention group had more satisfaction and less pain during labor than women from the non-intervention group.

Altered locomotor muscle metaboreflex control of ventilation in patients with COPD.

We investigated the locomotor muscle metaboreflex control of ventilation, circulation, and dyspnea in patients with chronic obstructive pulmonary disease (COPD). Ten patients [forced expiratory volume in 1 second (FEV1; means ± SD) = 43 ± 17% predicted] and nine age- and sex-matched controls underwent 1) cycling exercise followed by postexercise circulatory occlusion (PECO) to activate the metaboreflex or free circulatory flow to inactivate it, 2) cold pressor test to interpret whether any altered reflex response was specific to the metaboreflex arc, and 3) muscle biopsy to explore the metaboreflex arc afferent side. We measured airflow, dyspnea, heart rate, arterial pressure, muscle blood flow, and vascular conductance during reflexes activation. In addition, we measured fiber types, glutathione redox balance, and metaboreceptor-related mRNAs in the vastus lateralis. Metaboreflex activation increased ventilation versus free flow in patients (∼15%, P < 0.020) but not in controls (P > 0.450). In contrast, metaboreflex activation did not change dyspnea in patients (P = 1.000) but increased it in controls (∼100%, P < 0.001). Other metaboreflex-induced responses were similar between groups. Cold receptor activation increased ventilation similarly in both groups (P = 0.46). Patients had greater type II skeletal myocyte percentage (14%, P = 0.010), lower glutathione ratio (-34%, P = 0.015), and lower nerve growth factor (NGF) mRNA expression (-60%, P = 0.031) than controls. Therefore, COPD altered the locomotor muscle metaboreflex control of ventilation. It increased type II myocyte percentage and elicited redox imbalance, potentially producing more muscle metaboreceptor stimuli. Moreover, it decreased NGF expression, suggesting a downregulation of metabolically sensitive muscle afferents.NEW & NOTEWORTHY This study's integrative physiology approach provides evidence for a specific alteration in locomotor muscle metaboreflex control of ventilation in patients with COPD. Furthermore, molecular analyses of a skeletal muscle biopsy suggest that the amount of muscle metaboreceptor stimuli derived from type II skeletal myocytes and redox imbalance overcame a downregulation of metabolically sensitive muscle afferents.

Preoperative respiratory muscle training reduces the risk of pulmonary complications and the length of hospital stay after cardiac surgery: a systematic review.

QUESTIONS: What is the effect of preoperative respiratory muscle training (RMT) on the incidence of postoperative pulmonary complications (PPCs) after open cardiac surgery? What is the effect of RMT on the duration of mechanical ventilation, postoperative length of stay and respiratory muscle strength? DESIGN: Systematic review of randomised trials with meta-analysis. PARTICIPANTS: Adults undergoing elective open cardiac surgery. INTERVENTION: The experimental groups received preoperative RMT and the comparison groups received no intervention. OUTCOME MEASURES: The primary outcomes were PPCs, length of hospital stay, respiratory muscle strength, oxygenation and duration of mechanical ventilation. The methodological quality of studies was assessed using the PEDro scale and the overall certainty of the evidence was assessed using the GRADE approach. RESULTS: Eight trials involving 696 participants were included. Compared with the control group, the respiratory training group had fewer PPCs (RR 0.51, 95% CI 0.38 to 0.70), less pneumonia (RR 0.44, 95% CI 0.25 to 0.78), shorter hospital stay (MD -1.7 days, 95% CI -2.4 to -1.1) and higher maximal inspiratory pressure values at the end of the training protocol (MD 12 cmH2O, 95% CI 8 to 16). The mechanical ventilation time was similar in both groups. The quality of evidence was high for pneumonia, length of hospital stay and maximal inspiratory pressure. CONCLUSION: Preoperative RMT reduced the risk of PPCs and pneumonia after cardiac surgery. The training also improved the maximal inspiratory pressure and reduced hospital stay. The effects on PPCs were large enough to warrant use of RMT in this population. REGISTRATION: CRD42021227779.

TNFR1-mediated neuroinflammation is necessary for respiratory deficits observed in 6-hydroxydopamine mouse model of Parkinsons Disease.

Parkinson's Disease (PD) is characterized by classic motor symptoms related to movement, but PD patients can experience symptoms associated with impaired autonomic function, such as respiratory disturbances. Functional respiratory deficits are known to be associated with brainstem neurodegeneration in the mice model of PD induced by 6-hydroxydopamine (6-OHDA). Understanding the causes of neuronal death is essential for identifying specific targets to prevent degeneration. Many mechanisms can explain why neurons die in PD, and neuroinflammation is one of them. To test the influence of inflammation, mediated by microglia and astrocytes cells, in the respiratory disturbances associated with brainstem neurons death, we submitted wild-type (WT) and TNF receptor 1 (TNFR1) knockout male mice to the 6-OHDA model of PD. Also, male C57BL/6 animals were induced using the same PD model and treated with minocycline (45 mg/kg), a tetracycline antibiotic with anti-inflammatory properties. We show that degeneration of brainstem areas such as the retrotrapezoid nucleus (RTN) and the pre-Botzinger Complex (preBotC) were prevented in both protocols. Notably, respiratory disturbances were no longer observed in the animals where inflammation was suppressed. Thus, the data demonstrate that inflammation is responsible for the breathing impairment in the 6-OHDA-induced PD mouse model.

A expansão rápida da maxila e sua relação com a qualidade de vida em pacientes respiradores bucais / Rapid maxillary expansion and its relation with quality of life in mouth breathing patients

Este estudo avaliou, em curto prazo, mudanças após a expansão rápida da maxila em pacientes respiradores bucais e correlacionou esses achados com a qualidade de vida dos pacientes. Este estudo teve como objetivo avaliar se a expansão rápida da maxila (ERM) está associada à melhora na qualidade de vida pós-tratamento. Foram avaliadas 35 crianças (média de idade 10,3 anos) com respiração bucal com hipoplasia maxilar. Os sintomas subjetivos foram avaliados por questionário padronizado de qualidade de vida, respondido pelos pacientes e seus pais ou responsáveis legais pré e pós-ERM. As condições respiratórias subjetivas do pré-tratamento apresentaram melhora significativa seis meses após a ERM. Concluiu-se que a ERM promoveu melhora na qualidade de vida dos pacientes com respiração bucal e hipoplasia maxilar (AU)

This study evaluated short-term changes after rapid maxillary expansion in mouth breathing patients and correlated these findings with their quality of life. This study aimed to evaluate whether rapid maxillary expansion (RME) is associated with improved post-treatment quality of life. Thirty-five mouth breathing children (mean age 10.3 years old) with maxillary hypoplasia were evaluated. Subjective symptoms were assessed by a standardized quality of life questionnaire, answered by patients and their parents or legal guardians before and after RME. Pre-treatment subjective respiratory conditions showed significant improvement six months after RME. It was concluded that RME improves the quality of life for patients with mouth breathing and maxillary hypoplasia (AU)

Efeitos imediatos do inspirômetro de incentivo em mulheres vocalmente saudáveis / Immediate effects of the incentive spirometer in women with healthy voice

RESUMO Objetivo Avaliar o efeito imediato do inspirômetro de incentivo nas medidas acústicas, medidas aerodinâmicas e na avaliação perceptivo-auditiva da qualidade vocal de mulheres com vozes saudáveis. Método Trata-se de um estudo experimental de comparação intrassujeito que contou com a participação de 22 mulheres sem queixas vocais. Foram obtidas as medidas acústicas, medidas aerodinâmicas e a avaliação perceptivo-auditiva da qualidade vocal antes e imediatamente após o uso do inspirômetro de incentivo pelas participantes. O dispositivo foi utilizado na posição ortostática, e as participantes realizaram três séries de dez repetições com intervalo de um minuto entre as séries. Resultados Após uso do inspirômetro de incentivo, observou-se redução significativa nas medidas de jitter, shimmer e PPQ (period perturbation quociente) e aumento do volume expiratório máximo. As demais medidas acústicas e aerodinâmicas não foram impactadas significativamente. Além disso, houve melhora na avaliação perceptivo-auditiva da qualidade vocal em oito (36,4%) participantes, e 11 (50,0%) não apresentaram mudanças após uso do inspirômetro de incentivo. Conclusão O uso do inspirômetro de incentivo é seguro e, em seu efeito imediato, promove redução nas medidas acústicas de aperiodicidade a curto prazo, tanto relacionadas à frequência quanto à intensidade, e aumenta o volume expiratório máximo em mulheres com vozes saudáveis.

ABSTRACT Purpose To evaluate the immediate effect of the incentive spirometer on acoustic measures, aerodynamic measures and on the auditory-perceptual assessment of vocal quality in vocally healthy women. Methods This is an experimental intra-subject comparison study with the participation of 22 women without vocal complaints. Acoustic measures, aerodynamic measures and auditory-perceptual assessment of vocal quality were obtained before and immediately after using the incentive spirometer by the participants. The device was used in the orthostatic position and the participants performed three sets of ten repetitions with a one-minute interval between sets. Results After using the incentive spirometer, there was a significant reduction in jitter, shimmer and PPQ (period perturbation quotient) measurements and an increase in maximum expiratory volume, while the other acoustic and aerodynamic measurements were not significantly impacted. In addition, there was improvement in vocal quality in eight (36.4%) participants and 11 (50.0%) participants showed no changes in the auditory perceptual assessment of voice quality after using the incentive spirometer. Conclusion The use of the incentive spirometer is safe and, in its immediate effect, positively impacts the acoustic measures of short-term aperiodicity of frequency and intensity and increases the maximum expiratory volume in women with healthy voices.