The status and influencing factors of lung ventilation function in employees exposed to dust in enterprises of the XPCC, China.

Background: Occupational health is closely related to harmful factors in the workplace. Dust is the primary contributing factor causing impaired lung ventilation function among employees with dust exposure, and their lung ventilation function may also be influenced by other factors. We aimed at assessing the status and influencing factors of lung ventilation function among employees exposed to dust in the enterprises of the Eighth Division located in the Xinjiang Production and Construction Corps (XPCC), China. Methods: Employees exposed to dust in enterprises of the Eighth Division located in the XPCC in 2023 were selected as the subjects of this cross-sectional study. Their lung ventilation function indicators were extracted from health examination records, and an on-site electronic questionnaire survey was conducted among them. Binary logistic regression analyses were conducted to evaluate the factors influencing lung ventilation function. Results: According to the fixed value criteria, the abnormal rates of forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), and FEV1/FVC were 31.6, 1.4, and 0.4%, respectively. The lower limit of normal (LLN) criteria could overestimate the rate of abnormal lung ventilation function. Several factors were related to impaired lung ventilation function, including gender, age, education level, marital status, body mass index (BMI), smoking status, physical activity, the type of dust, industry, enterprise scale, occupation, length of service, working shift, monthly income, and respiratory protection. Conclusions: A relatively low abnormal rate of lung ventilation function was observed among employees exposed to dust in enterprises of the Eighth Division, XPCC, and their lung ventilation function was associated with various factors. Effective measures should be taken urgently to reduce the effects of adverse factors on lung ventilation function, thereby further protecting the health of the occupational population.

Comparable Ventilatory Inefficiency at Maximal and Submaximal Performance in COPD vs. CHF subjects: An Innovative Approach. / Ineficiência Ventilatória Comparável no Desempenho Máximo e Submáximo em Indivíduos com DPOC e ICC: Uma Abordagem Inovadora.

BACKGROUND: Currently, excess ventilation has been grounded under the relationship between minute-ventilation/carbon dioxide output ( V ˙ E - V ˙ CO 2 ). Alternatively, a new approach for ventilatory efficiency ( η E V ˙ ) has been published. OBJECTIVE: Our main hypothesis is that comparatively low levels of η E V ˙ between chronic heart failure (CHF) and chronic obstructive pulmonary disease (COPD) are attainable for a similar level of maximum and submaximal aerobic performance, conversely to long-established methods ( V ˙ E - V ˙ CO 2 slope and intercept). METHODS: Both groups performed lung function tests, echocardiography, and cardiopulmonary exercise testing. The significance level adopted in the statistical analysis was 5%. Thus, nineteen COPD and nineteen CHF-eligible subjects completed the study. With the aim of contrasting full values of V ˙ E - V ˙ CO 2 and η V ˙ E for the exercise period (100%), correlations were made with smaller fractions, such as 90% and 75% of the maximum values. RESULTS: The two groups attained matched characteristics for age (62±6 vs. 59±9 yrs, p>.05), sex (10/9 vs. 14/5, p>0.05), BMI (26±4 vs. 27±3 Kg m2, p>0.05), and peak V ˙ O 2 (72±19 vs. 74±20 %pred, p>0.05), respectively. The V ˙ E - V ˙ CO 2 slope and intercept were significantly different for COPD and CHF (27.2±1.4 vs. 33.1±5.7 and 5.3±1.9 vs. 1.7±3.6, p<0.05 for both), but η V ˙ E average values were similar between-groups (10.2±3.4 vs. 10.9±2.3%, p=0.462). The correlations between 100% of the exercise period with 90% and 75% of it were stronger for η V ˙ E (r>0.850 for both). CONCLUSION: The η V ˙ E is a valuable method for comparison between cardiopulmonary diseases, with so far distinct physiopathological mechanisms, including ventilatory constraints in COPD.

FUNDAMENTO: Atualmente, o excesso de ventilação tem sido fundamentado na relação entre ventilação-minuto/produção de dióxido de carbono ( V ˙ E − V ˙ CO 2 ). Alternativamente, uma nova abordagem para eficiência ventilatória ( η E V ˙ ) tem sido publicada. OBJETIVO: Nossa hipótese principal é que níveis comparativamente baixos de η E V ˙ entre insuficiência cardíaca crônica (ICC) e doença pulmonar obstrutiva crônica (DPOC) são atingíveis para um nível semelhante de desempenho aeróbico máximo e submáximo, inversamente aos métodos estabelecidos há muito tempo (inclinação V ˙ E − V ˙ CO 2 e intercepto). MÉTODOS: Ambos os grupos realizaram testes de função pulmonar, ecocardiografia e teste de exercício cardiopulmonar. O nível de significância adotada na análise estatística foi 5%. Assim, dezenove indivíduos elegíveis para DPOC e dezenove indivíduos elegíveis para ICC completaram o estudo. Com o objetivo de contrastar valores completos de V ˙ E − V ˙ CO 2 e η E V ˙ para o período de exercício (100%), correlações foram feitas com frações menores, como 90% e 75% dos valores máximos. RESULTADOS: Os dois grupos tiveram características correspondentes para a idade (62±6 vs 59±9 anos, p>.05), sexo (10/9 vs 14/5, p>0,05), IMC (26±4 vs 27±3 Kg m2, p>0,05), e pico V ˙ O 2 (72±19 vs 74±20 % pred, p>0,05), respectivamente. A inclinação V ˙ E − V ˙ CO 2 e intercepto foram significativamente diferentes para DPOC e ICC (207,2±1,4 vs 33,1±5,7 e 5,3±1,9 vs 1,7±3,6, p<0,05 para ambas), mas os valores médios da η E V ˙ foram semelhantes entre os grupos (10,2±3,4 vs 10,9±2,3%, p=0,462). As correlações entre 100% do período do exercício com 90% e 75% dele foram mais fortes para η E V ˙ (r>0,850 para ambos). CONCLUSÃO: A η E V ˙ é um método valioso para comparação entre doenças cardiopulmonares, com mecanismos fisiopatológicos até agora distintos, incluindo restrições ventilatórias na DPOC.

Comparative analysis of pulmonary ventilation distribution between low-cost and branded incentive spirometers using electrical impedance tomography in healthy adults: Study protocol.

BACKGROUND: The Incentive Spirometer (IS) increases lung volume and improves gas exchange by visually stimulating patients to take slow, deep breaths. It prevents respiratory complications and treats postoperative atelectasis in patients undergoing abdominal, thoracic, and neurosurgical procedures. Its effectiveness has been validated in studies that support improved lung capacities and volumes in individuals with respiratory complications, postoperative thoracic surgery, upper abdominal surgery, and bariatric surgery. The modified Pachón incentive spirometer (MPIS) is a cost-effective alternative to branded IS. It is crucial to validate whether the MPIS distributes ventilation as effectively as commercial devices do. Ventilation distribution will be measured using electrical impedance tomography. OBJECTIVE: The aim is to compare the distribution of pulmonary ventilation between the MPIS and another commercial IS in healthy adults using electrical impedance tomography. METHODS: A crossover clinical trial is proposed to evaluate the measurement of pulmonary ventilation distribution using EIT in a sample of healthy adults. All participants will use a commercial flow IS and the MPIS, with the order of assignment randomized. This research will use electrical impedance tomography to validate the operation of the MPIS. CONCLUSIONS: This study protocol will compare two incentive spirometers' impact on pulmonary ventilation, potentially endorsing the adoption of a cost-effective device to enhance accessibility for targeted populations. TRIAL REGISTRATION: The study was registered in ClinicalTrials.gov (NTC05532748).

Mechanisms and consequences of excess exercise ventilation in fibrosing interstitial lung disease.

The causes and consequences of excess exercise ventilation (EEV) in patients with fibrosing interstitial lung disease (f-ILD) were explored. Twenty-eight adults with f-ILD and 13 controls performed an incremental cardiopulmonary exercise test. EEV was defined as ventilation-carbon dioxide output (⩒E-⩒CO2) slope ≥36 L/L. Patients showed lower pulmonary function and exercise capacity compared to controls. Lower DLCO was related to higher ⩒E-⩒CO2 slope in patients (P<0.05). 13/28 patients (46.4%) showed EEV, reporting higher dyspnea scores (P=0.033). Patients with EEV showed a higher dead space (VD)/tidal volume (VT) ratio while O2 saturation dropped to a greater extent during exercise compared to those without EEV. Higher breathing frequency and VT/inspiratory capacity ratio were observed during exercise in the former group (P<0.05). An exaggerated ventilatory response to exercise in patients with f-ILD is associated with a blunted decrease in the wasted ventilation in the physiological dead space and greater hypoxemia, prompting higher inspiratory constraints and breathlessness.

Dysregulation of ventilation at day and night time in heart failure.

Heart failure (HF) is characterized by an increase in ventilatory response to exercise of multifactorial aetiology and by a dysregulation in the ventilatory control during sleep with the occurrence of both central and obstructive apnoeas. In this setting, the study of the ventilatory behaviour during exercise, by cardiopulmonary exercise testing, or during sleep, by complete polysomnography or simplified nocturnal cardiorespiratory monitoring, is of paramount importance because of its prognostic value and of the possible effects of sleep-disordered breathing on the progression of the disease. Moreover, several therapeutic interventions can significantly influence ventilatory control in HF. Also, rest daytime monitoring of cardiac, metabolic, and respiratory activities through specific wearable devices could provide useful information for HF management. The aim of the review is to summarize the main studies conducted at Centro Cardiologico Monzino on these topics.

Exercise oscillatory ventilation: the past, present, and future.

Exercise oscillatory ventilation (EOV) is a fascinating event that can be appreciated in the cardiopulmonary exercise test and is characterized by a cyclic fluctuation of minute ventilation, tidal volume, oxygen uptake, carbon dioxide production, and end-tidal pressure for oxygen and carbon dioxide. Its mechanisms stem from a dysregulation of the normal control feedback of ventilation involving one or more of its components, namely, chemoreflex delay, chemoreflex gain, plant delay, and plant gain. In this review, we intend to breakdown therapeutic targets according to pathophysiology and revise the prognostic value of exercise oscillatory ventilation in the setting of heart failure and other diagnoses.

Impacto de un Programa de Recuperación Funcional en Músculos Ventilatorios y Apendiculares en Pacientes Post-ventilación Mecánica por COVID-19 / Impact of a Functional Recovery Program on Ventilatory and Appendicular Muscles in Patients Post-mechanical Ventilation for COVID-19

Los pacientes con COVID-19 subsidiarios de ventilación mecánica (VM), evolucionan con consecuencias funcionales en la musculatura ventilatoria y apendicular que no necesariamente se abordan de manera diferenciada. El objetivo de esta investigación fue evaluar el impacto de un programa de recuperación funcional en estos pacientes y determinar si las intervenciones afectan de manera diferenciada a las funciones ventilatorias y musculatura apendicular, utilizando pruebas de bajo costo. Se evaluaron 47 pacientes con COVID-19 que estuvieron en VM. Posterior a una espirometría basal se les realizó; presión inspiratoria máxima (PIMáx), fuerza de prensión palmar (FPP), prueba de pararse y sentarse (PPS) y Prueba de caminata en 6 minutos (PC6m), antes y después del plan de intervención. Este programa incluyó ejercicios aeróbicos y de fuerza supervisados por dos sesiones semanales de 60 minutos durante 3 meses. Después del programa, se observaron mejoras significativas en la capacidad vital forzada (CVF), el volumen espiratorio en el primer segundo (VEF1) y la PIMáx. Se encontraron relaciones significativas entre estas mediciones y la distancia recorrida de la PC6m, la FPP y la PPS. En conclusión, el programa de recuperación funcional en pacientes con COVID-19 que requirieron VM, beneficia tanto la función ventilatoria como la fuerza muscular apendicular. Las pruebas de fuerza muscular apendicular pueden ser útiles para evaluar la recuperación ya que pueden entregar información diferenciada de sus rendimientos. Por último, se necesita más investigación para comprender mejor la respuesta de estos pacientes a la rehabilitación.

SUMMARY: Patients with COVID-19 requiring mechanical ventilation (MV) evolve with functional consequences in the ventilatory and appendicular muscles that are not necessarily addressed in a differentiated manner. The objective of this research was to evaluate the impact of a functional recovery program in these patients and determine if the interventions differentially affect ventilatory functions and appendicular muscles, using low- cost tests. 47 patients with COVID-19 who were on MV were evaluated. After a baseline spirometry, they were performed; maximum inspiratory pressure (MIP), handgrip strength (HGS), sit to stand test (STST) and 6-minute walk test (6MWT), before and after the intervention plan. This program included supervised aerobic and strength exercises for two weekly 60-minute sessions for 3 months. After the program, significant improvements were observed in forced vital capacity (FVC), expiratory volume in the first second (FEV1) and MIP. Significant relationships were found between these measurements and the distance traveled of the 6MWT, the HGS and the STST. In conclusion, the functional recovery program in patients with COVID-19 who required MV benefits both ventilatory function and appendicular muscle strength. Appendicular muscle strength tests can be useful to evaluate recovery since they can provide differentiated information about your performances. Finally, more research is needed to better understand the response of these patients to rehabilitation.

The hypoxic ventilatory response and hypoxic burden are predictors of the magnitude of ventilatory long-term facilitation in humans.

Mild intermittent hypoxia initiates progressive augmentation (PA) and ventilatory long-term facilitation (vLTF) in humans. The magnitude of these forms of plasticity might be influenced by anthropometric and physiological variables, as well as protocol elements. However, the impact of many of these variables on the magnitude of respiratory plasticity has not been established in humans. A meta-analysis was completed using anthropometric and physiological variables obtained from 124 participants that completed one of three intermittent hypoxia protocols. Simple correlations between the aggregate variables and the magnitude of PA and vLTF standardized to baseline was completed. Thereafter, the variables correlated to PA or vLTF were input into a multilinear regression equation. Baseline measures of the hypoxic ventilatory response was the sole predictor of PA (R = 0.370, P = 0.012). Similarly, this variable along with the hypoxic burden predicted the magnitude of vLTF (R = 0.546, P < 0.006 for both variables). In addition, the magnitude of PA was strongly correlated to vLTF (R = 0.617, P < 0.001). Anthropometric measures do not predict the magnitude of PA and vLTF in humans. Alternatively, the hypoxic ventilatory response was the sole predictor of PA, and in combination with the hypoxic burden, predicted the magnitude of vLTF. These influences should be considered in the design of mild intermittent hypoxia protocol studies in humans. Moreover, the strong correlation between PA and vLTF suggests that a common mechanistic pathway may have a role in the initiation of these forms of plasticity. KEY POINTS: Mild intermittent hypoxia initiates progressive augmentation (PA) and ventilatory long-term facilitation (vLTF) in humans. Many of the anthropometric and physiological variables that could impact the magnitude of these forms of plasticity are unknown. Anthropometric and physiological variables were measured from a total of 124 participants that completed one of three distinct intermittent hypoxia protocols. The variables correlated to PA or vLTF were input into a multilinear regression analysis. The hypoxic ventilatory response was the sole predictor of PA, while this variable in addition to the average hypoxic burden predicted the magnitude of vLTF. A strong correlation between PA and vLTF was also revealed. These influences should be considered in the design of mild intermittent hypoxia protocol studies in humans. Moreover, the strong correlation between PA and vLTF suggests that a common mechanistic pathway may have a role in the initiation of these forms of plasticity.

Influence of chronic hypoxia on the hypoxic ventilatory response of juvenile and adult rats.

Chronic hypoxia (CH) from birth attenuates the acute hypoxic ventilatory response (HVR) in rats and other mammals, but CH is often reported to augment the HVR in adult mammals. To test the hypothesis that this transition - from blunting to augmenting the HVR - occurs in the third or fourth postnatal week in rats, juvenile and adult rats were exposed to normobaric CH (12% O2) for 7 days and the HVR was assessed by whole-body plethysmography. No transition was observed, however, and the acute HVR was reduced by 61 - 85% across all ages studied. The failure to observe an augmented HVR in adult rats could not be explained by the substrain of Sprague Dawley rats used, the duration of the CH exposure, the order in which test gases were presented, the level of hypoxia used for CH and to assess the HVR, or the effects of CH on the metabolic response to hypoxia and the hypercapnic ventilatory response. A literature survey revealed several distinct patterns of ventilatory acclimatization to hypoxia (VAH) in adult rats, with most studies (77%) revealing a decrease or no change in the acute HVR after CH. In conclusion, the effects of CH on respiratory control are qualitatively similar across age groups, at least within the populations of Sprague Dawley rats used in the present study, and there does not appear to be one "typical" pattern for VAH in adult rats.

Fractal dimension of pulmonary gas and blood distribution assessed by synchrotron K-edge subtraction imaging: effect of bronchoconstriction.

We analyzed the fractal dimension (Df) of lung gas and blood distribution imaged with synchrotron radiation K-edge subtraction (KES), in six anesthetized adult New Zealand White rabbits. KES imaging was performed in upright position during stable Xe gas (64% in O2) inhalation and iodine infusion (Iomeron, 350 mg/mL), respectively, at baseline and after induced bronchoconstriction by aerosolized methacholine (125 mg/mL, 90 s) and bronchodilator (salbutamol, 10 mg/mL, 90 s) inhalation, at two axial image levels. Lung Xe and iodine images were segmented, and maps of regional lung gas and blood fractions were computed. The Df of lung gas (DfXe) and blood (DfIodine) distribution was computed based on a log-log plot of variation coefficient as a function of region volume. DfXe decreased significantly during bronchoconstriction (P < 0.0001), and remained low after salbutamol. DfIodine depended on the axial image level (P < 0.0001), but did not change with bronchoconstriction. DfXe was significantly associated with arterial [Formula: see text] (R = 0.67, P = 0.002), and negatively associated with [Formula: see text] (R = -0.62, P = 0.006), respiratory resistance (R = -0.58, P = 0.011), and elastance (R = -0.55, P = 0.023). These data demonstrate the reduced Df of gas distribution during acute bronchoconstriction, and the association of this parameter with physiologically meaningful variables. This finding suggests a decreased complexity and space-filling properties of lung ventilation during bronchoconstriction, and could serve as a functional imaging biomarker in obstructive airway diseases.NEW & NOTEWORTHY Here, we used an energy-subtractive imaging technique to assess the fractal dimension (Df) of lung gas and blood distribution and the effect of acute bronchoconstriction. We found that Df of gas significantly decreases in bronchoconstriction. Conversely, Df of blood exhibits gravity-dependent changes only, and is not affected by acute bronchoconstriction. Our data show that the fractal dimension of lung gas detects the emergence of clustered rather than scattered loss of ventilatory units during bronchoconstriction.

Six Months of Exercise Training Improves Ventilatory Responses during Exercise in Adults with Well-Healed Burn Injuries.

INTRODUCTION: Pulmonary function is lower after a severe burn injury, which could influence ventilatory responses during exercise. It is unclear whether exercise training improves pulmonary function or ventilatory responses during exercise in adults with well-healed burn injuries. Therefore, we tested the hypothesis that exercise training improves pulmonary function and ventilatory responses during exercise in adults with well-healed burn injuries. METHODS: Thirty-nine adults (28 with well-healed burn injuries and 11 non-burn-injured controls) completed 6 months of unsupervised, progressive exercise training including endurance, resistance, and high-intensity interval components. Before and after exercise training, we performed comprehensive pulmonary function testing and measured ventilatory responses during cycling exercise. We compared variables using two-way ANOVA (group-time; i.e., preexercise/postexercise training (repeated factor)). RESULTS: Exercise training did not increase percent predicted spirometry, lung diffusing capacity, or airway resistance measures (time: P ≥ 0.14 for all variables). However, exercise training reduced minute ventilation ( V̇E ; time: P ≤ 0.05 for 50 and 75 W) and the ventilatory equivalent for oxygen ( V̇E /V̇O 2 ; time: P < 0.001 for 75 W) during fixed-load exercise for both groups. The ventilatory equivalent for carbon dioxide ( V̇E /V̇CO 2 ) during exercise at 75 W was reduced after exercise training (time: P = 0.04). The percentage of age-predicted maximum heart rate at the ventilatory threshold was lower in adults with well-healed burn injuries before ( P = 0.002), but not after ( P = 0.22), exercise training. Lastly, exercise training increased V̇E and reduced V̇E /V̇O 2 during maximal exercise (time: P = 0.005 for both variables). CONCLUSIONS: These novel findings demonstrate that exercise training can improve ventilatory responses during exercise in adults with well-healed burn injuries.

Software development to standardize the clinical diagnosis of exercise oscillatory ventilation in heart failure.

BACKGROUND: Exercise oscillatory ventilation (EOV) is characterized by periodic oscillations of minute ventilation during cardiopulmonary exercise testing (CPET). Despite its prognostic value in chronic heart failure (HF), its diagnosis is complex due to technical limitations. An easier and more accurate way of EOV identification can contribute to a better approach and clinical diagnosis. This study aims to describe a software development to standardize the EOV diagnosis from CPET's raw data in heart failure patients and test its reliability (intra- and inter-rater). METHODS: The software was developed in the "drag-and-drop" G-language using LabVIEW®. Five EOV definitions (Ben-Dov, Corrà, Kremser, Leite, and Sun definitions), two alternative approaches, one smoothing technique, and some basic statistics were incorporated into the interface to visualize four charts of the ventilatory response. EOV identification was based on a set of criteria verified from the interaction between amplitude, cycle length, and oscillation time. Two raters analyzed the datasets. In addition, repeated measurements were verified after six months using about 25% of the initial data. Cohen's kappa coefficient (κ) was used to investigate the reliability. RESULTS: Overall, 391 tests were analyzed in duplicate (inter-rater reliability) and 100 tests were randomized for new analysis (intra-rater reliability). High inter-rater (κ > 0.80) and intra-rater (κ > 0.80) reliability of the five EOV diagnoses were observed. CONCLUSION: The present study proposes novel semi-automated software to detect EOV in HF, with high inter and intra-rater agreements. The software project and its tutorial are freely available for download.

The effect of orexin on the hypoxic ventilatory response of female rats is greatest in the active phase during diestrus.

We recently showed that in male rats, orexin contributes to the hypoxic ventilatory response (HVR), with a stronger effect in the active phase. The effect of orexin on the HVR in females has not been investigated. As estrogen can inhibit orexin neurons, here we hypothesized that orexin neurons are activated by hypoxia and facilitate the HVR only in diestrus, when estrogen is low. We exposed female rats (n = 10) to near-isocapnic hypoxia ([Formula: see text] from 0.21 to 0.09) over ∼5 min, after vehicle and again after suvorexant (a dual OxR antagonist; 20 mg/kg ip), with ventilation measured using whole body plethysmography. Each rat was tested in proestrus or estrus (p/estrus), and again in diestrus, during both inactive and active phases. We also performed immunohistochemistry (IHC) to determine the proportion of orexin neurons activated by acute hypoxia during diestrus (n = 6) or proestrus/estrus (n = 6) in the active phase. In the inactive phase, the HVR was unaffected by OxR blockade, irrespective of estrus stage. In the active phase, the effect of OxR blockade depended on stage: the slope of the HVR was significantly reduced by OxR blockade only during diestrus. IHC revealed that hypoxia activated more orexin neurons during diestrus compared with p/estrus. We conclude that in females, orexin neurons are activated by hypoxia and contribute to the HVR only in diestrus when estrogen levels are low. Stage of the estrus cycle should be considered when examining the physiological function of orexin neurons in females.NEW & NOTEWORTHY We previously showed that orexin facilitates the hypoxic ventilatory response (HVR) of adult male rats during the active phase. Others have shown that estrogen inhibits orexin neurons. Here we show that orexin neurons are activated by hypoxia and facilitate the HVR of adult female rats during the active phase, but only in diestrus. These data suggest that orexin neurons facilitate the HVR in females when they are free from the inhibitory effects of estrogen.

Recovery of the biphasic hypoxic ventilatory response in neonatal rats after chronic hyperoxia.

Newborn mammals exhibit biphasic hypoxic ventilatory responses (HVR) characterized by an initial increase in ventilation and a secondary ventilatory depression. The magnitude of the hypoxic ventilatory decline (HVD) in the late phase of the HVR normally decreases with age, but this occurs sooner in rats reared in 60% O2. We investigated whether a lower level of hyperoxia (30% O2) or a short period of recovery (1 or 3 d in 21% O2) would affect the expression of this plasticity. Similar to 60% O2, rat pups reared in 30% O2 until 3-4 days of age exhibited a less biphasic HVR to 12% O2. When pups reared in 60% O2 were returned to normoxia, the magnitude of HVD increased such that pups expressed a biphasic HVR appropriate for their chronological age. Blocking synaptic input from the carotid bodies revealed that CNS hypoxia depressed ventilation less in hyperoxia-reared rats immediately following hyperoxia and after 1 d in normoxia despite recovery of the biphasic HVR. This suggests that recovery of the biphasic HVR occurs in pathways regulating HVD that depend on carotid body activity. The early, carotid body-mediated phase of the HVR was also blunted immediately and 1 d after the hyperoxia exposure, but not after 3 d of recovery. These data confirm that short exposures to mild-to-moderate hyperoxia elicit developmental plasticity in the HVR. However, reemergence of the biphasic HVR after return to normoxia argues against a heterokairic process for the premature transition from biphasic HVR to sustained HVR in hyperoxia-reared rat pups.

Airflow Analysis in the Context of Sleep Apnea.

The airflow (AF) is a physiological signal involved in the overnight polysomnography (PSG) that reflects the respiratory activity. This signal is able to show the particularities of sleep apnea and is therefore used to define apneic events. In this regard, a growing number of studies have shown the usefulness of employing the overnight airflow as the only or combined information source for diagnosing sleep apnea in both children and adults. Due to its easy acquisition and interpretation, this biosignal has been widely analyzed by means of different signal processing techniques. In this chapter, we review the main methodological approaches applied to characterize and extract relevant information from this signal. In view of the results, we can conclude that the overnight airflow successfully reflects the particularities caused by the occurrence of apneic and hypopneic events and provides useful information for obtaining relevant biomarkers that characterize this disease.

A deep look into the rib cage compression technique in mechanically ventilated patients: a narrative review. / Desvendando a técnica de compressão torácica em pacientes em ventilação mecânica: uma revisão narrativa.

Defective management of secretions is one of the most frequent complications in invasive mechanically ventilated patients. Clearance of secretions through chest physiotherapy is a critical aspect of the treatment of these patients. Manual rib cage compression is one of the most practiced chest physiotherapy techniques in ventilated patients; however, its impact on clinical outcomes remains controversial due to methodological issues and poor understanding of its action. In this review, we present a detailed analysis of the physical principles involved in rib cage compression technique performance, as well as the physiological effects observed in experimental and clinical studies, which show that the use of brief and vigorous rib cage compression, based on increased expiratory flows (expiratory-inspiratory airflow difference of > 33L/minute), can improve mucus movement toward the glottis. On the other hand, the use of soft and gradual rib cage compression throughout the whole expiratory phase does not impact the expiratory flows, resulting in ineffective or undesired effects in some cases. More physiological studies are needed to understand the principles of the rib cage compression technique in ventilated humans. However, according to the evidence, rib cage compression has more potential benefits than risks, so its implementation should be promoted.

O manejo deficiente das secreções é uma das complicações mais frequentes em pacientes em ventilação mecânica invasiva. A depuração das secreções por meio da fisioterapia respiratória é um aspecto crítico do tratamento desses pacientes. A compressão torácica manual é uma das técnicas de fisioterapia respiratória mais praticadas em pacientes ventilados, mas seu impacto nos desfechos clínicos permanece controverso devido a questões metodológicas e ao pouco conhecimento sobre sua ação. Nesta revisão, apresenta-se uma análise detalhada dos princípios físicos envolvidos na execução da técnica de compressão torácica. Também investigam-se os efeitos fisiológicos observados em estudos experimentais e clínicos, que mostram que o uso de compressão torácica curta e vigorosa, baseada no aumento de fluxos expiratórios (diferença de fluxo aéreo inspiratório-expiratório > 33L/minuto), pode melhorar o movimento do muco em direção à glote. Por outro lado, o uso de compressão torácica suave e gradual ao longo de toda a fase expiratória não afeta os fluxos expiratórios, resultando em efeitos ineficazes ou indesejados em alguns casos. Mais estudos fisiológicos são necessários para entender os princípios da técnica de compressão torácica em pacientes ventilados. No entanto, de acordo com as evidências, a compressão torácica tem mais benefícios potenciais do que riscos, o que incentiva sua implementação.

Regional ventilation distribution in patients with scoliosis assessed by electrical impedance tomography: Is individual thorax shape required?

BACKGROUND: Electrical impedance tomography (EIT) is a non-invasive non-radiological regional lung function measurement. The aim of the study was to examine the feasibility of assessing ventilation distribution with EIT in scoliosis patients using generic and individual thorax shape. METHODS: Eight subjects were measured with EIT before scoliosis surgery. Reconstructions with two different forward models were compared: the generic shape and the individual thorax shapes. Three EIT-based parameters measuring ventilation distribution were calculated: left lung to overall ratio, center of ventilation (CoV), global inhomogeneity index. RESULTS: EIT measurements were successfully conducted in all subjects. No statistical differences were found in the EIT-based parameters using the different reconstruction models. CoV based on the generic shape was significantly correlated to the main Cobb angle (r=-0.84, p < 0.01). CONCLUSION: It was feasible to monitor regional ventilation distribution in scoliosis patients with EIT. Individual thorax shapes might not be required for reliable patient assessment in a clinical setting.