Ventilatory Pattern Research Articles

COVID-19 After Effects: Concerns for Singers

COVID-19 After Effects: Concerns for Singers

Associations of long-term exposure to ambient fine particulate matter and nitrogen dioxide with lung function: A cross-sectional study in China

BackgroundFew studies have evaluated the effects of ambient air pollution exposure on lung function, especially in areas with high air pollution levels. ObjectivesTo investigate the associations of annual concentrations of particulate matter with diameters < 2.5 μm (PM2.5) and nitrogen dioxide (NO2) with adult lung function in Shanghai, China. MethodsWe included 5276 permanent residents aged ≥ 20 years. Annual residential exposure to PM2.5 and NO2 was estimated by validated satellite-based and land use regression models, respectively. The effects of PM2.5 and NO2 on lung function were estimated separately using multivariable linear regression, adjusting for potential confounders. ResultsHigher exposure to PM2.5 and NO2 was significantly associated with lower forced vital capacity (FVC), inspiration capacity (IC), and vital capacity (VC). An increase of 10 μg/m3 in the annual average PM2.5 exposure was associated with a 45.83 ml (95% CI: −82.59, −9.07) lower FVC, 1.36 (95% CI: −2.42, −0.29) lower FVC of % predicted (FVC%pred), 121.98 ml (95% CI: −164.38, −79.57) lower IC, and 89.12 ml (95% CI −124.94, −53.3) lower VC. For NO2, an increase of 10 μg/m3 in the annual average concentration was associated with 26.65 ml (95% CI: −46.29, −7.00) lower FVC, 0.70 (95% CI: −1.27, 0.13) lower FVC%pred, 65.26 ml (95% CI: −87.76, −42.76) lower IC, and 45.88 ml (95% CI: −65.03, −26.73) lower VC. The estimated effects on FEV1 were −10.25 ml (95% CI: −40.92, 20.42) and −0.29% (95% CI: −1.40, 0.82) per 10 μg/m3 increase in PM2.5 and −0.74 ml (95% CI: −17.13, 15.65) and 0.01% (95% CI: −0.58, 0.61) per 10 μg/m3 increase in NO2, which were not statistically significant. Stratified analysis showed that the estimated effects of PM2.5 were greater in the healthy subgroup than the COPD patients. Obese individuals were more susceptible to adverse effects of PM2.5 and NO2 on lung function. Education level showed no or only weak evidence of modification of the associations between air pollution and lung function. ConclusionIn this study, long-term exposure to ambient air pollutants was significantly associated with impaired lung function, presenting as restrictive ventilatory patterns.

Skin-to-skin care alters regional ventilation in stable neonates

ObjectiveSkin-to-skin care (SSC) has proven psychological benefits; however, the physiological effects are less clearly defined. Regional ventilation patterns during SSC have not previously been reported. This study aimed to compare...

In COPD, Nocturnal Noninvasive Ventilation Reduces the FIO2 Delivered Compared With Long-Term Oxygen Therapy at the Same Flow.

Nocturnal noninvasive ventilation is recommended for patients with hypercapnic COPD. Long-term oxygen therapy improves survival in patients with hypoxemic disease. However, leaks during noninvasive ventilation are likely to reduce the fraction of inspired oxygen. To compare nocturnal inspired O2 fractions during noninvasive ventilation with daytime pharyngeal inspired O2 fractions during nasal cannula oxygen therapy (with the same O2 flow) in patients with COPD at home (ie, real-life conditions). This single-center prospective observational study included 14 subjects with COPD who received long-term O2 therapy. We analyzed pharyngeal inspired O2 fractions in the evening, with a nasopharyngeal probe (sidestream gas analyzer). The O2 flow was measured with a precision flow meter, at the usual flow. Then, the same O2 flow was implemented for noninvasive ventilation with a study's home ventilator. The all-night noninvasive ventilation parameters were delivered in pressure mode with a single-limb leaking circuit. Daytime and nighttime inspired O2 fractions were compared. The mean ± SD daytime pharyngeal inspired O2 fraction, measured with normobaric basal O2 flow, 0.308 ± 0.026%, was significantly higher than the mean ± SD nighttime inspired O2 fraction, measured during noninvasive ventilation (0.251 ± 0.011; P < .001). The nighttime inspired O2 fraction decreased with a modern noninvasive ventilation pattern, pressure target, and intentional leaks. This partial lack of O2 therapy is likely to be harmful. It might explain the poor results in all but 2 randomized controlled trials on long-term noninvasive ventilation in COPD. (ClinicalTrials.gov registration NCT02599246.).

Inspiratory Muscle Training Potentiates the Beneficial Effects of Proportional Assisted Ventilation on Exertional Dyspnea and Exercise Tolerance in COPD: A Proof-of-Concept Randomized and Controlled Trial

During pulmonary rehabilitation, a subset of subjects with COPD requires adjunct therapy to achieve high-intensity training. Both noninvasive ventilation (NIV) and inspiratory muscle training (IMT) are available to assist these subjects. We aimed to prime the respiratory muscles before NIV with IMT, anticipating additive effects for maximal exercise tolerance (T lim) and dyspnea/leg fatigue relief throughout the exercise as primary outcomes. Changes in the respiratory pattern were secondary outcomes. COPD subjects performed a total of four identical constant work rate tests on a cycle ergometer at 75% of maximum work rate, under control ventilation (SHAM, 4 cm H2O) or proportional assisted ventilation (PAV, individually adjusted), before and after 10 sessions of high-intensity IMT (three times/week) during 30 days. Two-way RM ANOVA with appropriate corrections were performed. Final analysis in nine subjects showed improved T lim (Δ = 111 s) and lower minute-ventilation (Δ = 4 L.min−1) at exhaustion, when comparing the IMT effects within the PAV modality (p = 0.001 and p = 0.036, respectively) and improved T lim for PAV vs. SHAM (PAV main-effect, p = 0.001; IMT main-effect, p = 0.006; PAV vs. IMT interaction, p = 0.034). In addition, IMT + PAV association, compared to PAV alone, resulted in lower respiratory frequency (IMT main-effect, p = 0.009; time main-effect, p < 0.0001; IMT vs. time interaction, p = 0.242) and lower inspiratory time related to duty cycle (IMT main-effect, p = 0.018; time main-effect, p = 0.0001; IMT vs. time interaction, p = 0.004) throughout exercise. The addition of IMT prior to a PAV-supported aerobic bout potentiates exercise tolerance and dyspnea relief and induces favourable changes in ventilatory pattern in severe COPD during high-intensity training (Brazilian Registry of Clinical Trials, number RBR-6n3dzz).

Ventilación mecánica en cirugía cardíaca: actualidades

Introducción: La ventilación mecánica en la cirugía cardíaca constituye un reto anestesiológico, los nuevos protocolos de recuperación posquirúrgica mejorada (ERAS, en inglés) incluye, entre otros, ventilación mecánica protectiva determinada por bajos volúmenes corrientes, presión positiva al final de la espiración (PEEP) moderada, fracción inspiratoria de oxígeno (FiO2) que mantengan normoxemia, factores que influyen el posquirúrgico y en las complicaciones pulmonares. Es importante determinar que existen varios momentos en la cirugía cardíaca que modificara el patrón ventilatorio dependiendo del bypass cardiopulmonar, circulación con bomba extracorpórea, ventilación unipulmonar.&#x0D; Objetivo: Proporcionar la mejor evidencia científica en el manejo intraoperatorio de la ventilación mecánica en pacientes sometidos a cirugía cardíaca.&#x0D; Material y métodos: Se realizó una revisión sistemática de la literatura científica publicada en el periodo 2015-2020. Se realizó una búsqueda en los sitios a continuación utilizando los siguientes términos: “mechanical ventilation”, “ventilation”, “cardiac surgery”, “airway management”, “airway extubation”, “cardiopulmonary bypass”, “coronary artery bypass”, “coronary artery bypass, off-Pump”, “anesthesia, general”, “anesthesia recovery period”, “emergence delirium” en bases de datos: Medline, Best Practice &amp; Research Clinical Anaesthesiology, Current Opinion in Anaesthesiology, Journal of Cardiothoracic and Vascular Anesthesia y Annals of Cardiac Anaesthesia.&#x0D; Resultados: La mejor evidencia científica sugiere que la ventilación mecánica en cirugía cardíaca debe proporcionarse bajo el modelo protectivo para mejores resultados posquirúrgicos inmediatos y mortalidad a largo plazo.&#x0D; Conclusiones: La ventilación mecánica protectiva ofrece menores complicaciones pulmonares posoperatorias, debe respetarse los volúmenes corrientes bajos en base al peso predicho del paciente, mantener PEEP moderada, FiO2 entre 40 – 60% para mantener normoxemia. Los protocolos de recuperación posquirúrgica mejorada (ERAS) se han establecido en el manejo de pacientes sometidos a cirugía cardíaca con mejores resultados globales en morbimortalidad.

Relationship between ventilatory pattern and peak VO2 and area M regulates the respiratory system during exercise

BackgroundExertional dyspnea is a major symptom of heart failure. We investigated the tidal volume (TV)-the respiratory rate (RR) regulation according to the peak O2 uptake (VO2) during cardiopulmonary exercise testing (CPET) for clarifying exercise ventilatory pattern. MethodsWe enrolled 1111 patients (66±13 years old, 68% men) who had undergone CPET at our hospital. We investigated the relationship between TV and RR and drew the TV/height-RR figure according to the %peak VO2. ResultsDuring exercise, TV was greater, illustrated as higher %peak VO2. However, RR was weakly correlated with %peak VO2. Adjusted with age, height, sex, each point of RR, and %peak VO2, TV during exercise highly correlated with age, height, each point of RR, and % peak VO2 (R=0.726 to 0.821, p<0.01). In the figure, regardless of the %peak VO2, TV/height and RR values were linearly related at rest, as well as at the point of anaerobic threshold, respiratory compensation, and peak exercise point, with each of these lines converging onto a single area (area M). The TV-RR slope values at early phase were also lower at lower %peak VO2. ConclusionsWe identified three ventilatory regularities during exercise. First, TV increases as greater %peak VO2. Second, the line relating TV/height and RR at each reference point during the incremental exercise test converged onto area M. Finally, the TV-RR slope at the early exercise phase was lower in patients with a lower %peak VO2. These ventilatory regularities may assist in elucidating the excise ventilatory pattern and help the diagnosis of exertional dyspnea.

Deterioration of Nighttime Respiratory Mechanics in COPD: Impact of Bronchodilator Therapy

COPD is associated with nighttime respiratory symptoms, poor sleep quality, and increased risk of nocturnal death. Overnight deterioration of inspiratory capacity (IC) and FEV1 have been documented previously. However, the precise nature of this deterioration and mechanisms by which evening bronchodilation may mitigate this occurrence have not been studied. What is the effect of evening dosing of dual, long-acting bronchodilation on detailed nocturnal respiratory mechanics and inspiratory neural drive (IND)? A double-blind, randomized, placebo-controlled crossover study assessed the effects of evening long-acting bronchodilation (aclidinium bromide/formoterol fumarate dihydrate: 400/12 μg) or placebo on morning trough IC (12h after the dose; primary outcome) and serial overnight measurements of spirometry, dynamic respiratory mechanics, and IND (secondary outcomes). Twenty participants with COPD (moderate/severe airway obstruction and lung hyperinflation) underwent serial measurements of IC, spirometry, breathing pattern, esophageal and transdiaphragmatic pressures, and diaphragm electromyography (diaphragmatic electromyography as a percentage of maximum; IND) at 6 time points from 0 to 12h after the dose and compared with sleeping IND. Compared with placebo, evening bronchodilation was not associated with increased morning trough IC 12h after the dose (P= .48); however, nadir IC (lowest IC, independent of time), peak IC, area under the curve for 12h after the dose, and IC for 10h after the dose were improved (P< .05). During placebo, total airways resistance, lung hyperinflation, IND, and tidal esophageal and transdiaphragmatic pressure swings all increased significantly overnight compared with baseline evening values; however, each of these parameters improved with bronchodilator treatment (P< .05) with no change in ventilation or breathing pattern. Respiratory mechanics significantly deteriorated at night during placebo. Although the morning trough IC was unchanged, evening bronchodilator treatment was associated consistently with sustained overnight improvements in dynamic respiratory mechanics and inspiratory neural drive compared with placebo CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT02429765.

Comparison of different methods for lung immobilization in an animal model

Background and purposeRespiratory-induced motion introduces uncertainties in the delivery of dose in radiotherapy treatments. Various methods are used clinically, e.g. breath-holding, while there is limited experience with other methods such as apneic oxygenation and high frequency jet ventilation (HFJV). This study aims to compare the latter approaches for lung immobilization and their clinical impact on gas exchange in an animal model. Materials and methodsTwo radiopaque tumor surrogate markers (TSM) were placed in the central (cTSM) and peripheral (dTSM) regions of the lungs in 9 anesthetized and muscle relaxed pigs undergoing 3 ventilatory interventions (1) HFJV at rates of 200 (JV200), 300 (JV300) and 400 (JV400) min−1; (2) apnea at continuous positive airway pressure (CPAP) levels of 0, 8 and 16 cmH2O; (3) conventional mechanical ventilation (CMV) as reference mode. cTSM and dTSM were visualized using fluoroscopy and their coordinates were computed. The ventilatory pattern was registered, and oxygen and carbon dioxide (pCO2) partial pressures were measured. ResultsThe highest range of TSM motion, and ventilation was found during CMV, the lowest during apnea. During HFJV the amount of motion varied inversely with increasing frequency. The reduction of TSM motion at JV300, JV400 and all CPAP levels came at the cost of increased pCO2, however the relatively low frequency of 200 min−1 for HFJV was the only ventilatory setting that enabled adequate CO2 removal. ConclusionIn this model, HFJV at 200 min−1 was the best compromise between immobilization and gas exchange for sessions of 10-min duration.

Edematous myositis: a clinical presentation first suggesting dermatomyositis diagnosis.

Edema of the limbs is uncommon in idiopathic inflammatory myopathies (IIM). The few reported cases have been associated with severe and refractory dermatomyositis (DM), sometimes in association with cancers. We aimed to determine if edematous myositis is a homogeneous subtype based on clinical, serological and pathological features. This is a retrospective observational study performed between 2008 and 2015 in the French national referral center for myositis. All adult patients with an inflammatory muscle biopsy and upper limbs edema were included as well as IIM cases without limb edema as controls. Clinical, biological and pathological features were collected. Seventeen edematous myositis were included and compared to 174 IIM without edema, including 50 DM controls. Edema was the first manifestation in 23% of patients. Muscle weakness was severe and symmetric, 71% of patients presented dysphagia and a restrictive ventilatory pattern was found in 40%. Fifty-two percent of patients had a typical DM skin rash and 23% had cancer within 3years of diagnosing myositis. Fifty-three percent of patients presented a myositis specific antibody and only DM-specific antibodies were detected. Classic pathological DM features (perifascicular atrophy, perifascicular/perimysial perivascular inflammation) were uncommon but capillary C5b-9 deposition and MxA expression were seen in 79% and 73% of cases, respectively. A perimysial edema was found in 82% of cases. Seventeen percent of patients died (median follow up of 18months). Edematous myositis demonstrated more marked capillary C5b-9 deposition compared to IIM controls. There was no clinical, biological or pathological difference with DM controls except for limb edema. Our study underlines that limb edema could be a symptom of IIM and that edematous myositis are mostly DM. The vasculopathy seems to play a key role in its pathophysiology. Limb edema associated with muscle impairment should suggest the diagnosis of DM in clinical settings.

Mixed Ventilatory Defects in Pulmonary Sarcoidosis: Prevalence and Clinical Features

In cohort studies of pulmonary sarcoidosis, abnormal ventilatory patterns have generally been subdivided into restrictive and obstructive defects. Mixed ventilatory defects have largely been overlooked in pulmonary sarcoidosis, as total lung capacity has seldom been taken into account in historical series. This study evaluated the prevalence of mixed disease in pulmonary sarcoidosis and its clinical associations. In patients with pulmonary sarcoidosis (N= 1,110), mixed defects were defined according to American Thoracic Society/European Respiratory Society criteria. Clinical data, pulmonary function variables, and vital status were abstracted from clinical records. Chest radiographs were evaluated independently by two experienced radiologists. The prevalence of a mixed ventilatory defect was 10.4%in the whole cohort, rising to 25.9%in patients with airflow obstruction. Compared with isolated airflow obstruction, mixed defects were associated with lower diffusing lung capacity for carbon monoxide levels (50.7 ± 16.3 vs70.8 ± 18.1; P< .0001), a higher prevalence of chest radiographic stage IV disease (63.5%vs38.3%; P< .0001), and higher mortality (hazard ratio, 2.36; 95%CI, 1.34-4.15; P= .003). These findings were reproduced in all patient subgroup analyses, including patients with a histologic diagnosis, a clinical diagnosis, incident disease, and prevalent disease. Mixed disease is present in approximately 25%of patients with pulmonary sarcoidosis and airflow obstruction and is associated with lower diffusing lung capacity for carbon monoxide levels, a higher prevalence of stage IV disease, and higher mortality than seen in a pure obstructive defect. These observations identify a distinct phenotype associated with a mixed ventilatory defect, justifying future studies of its clinical and pathogenetic significance.

Lung function and functional exercise capacity in underground semi-precious stone mineworkers.

Semi-precious stone mining may cause occupational lung disease. The impact of inhaling silica on workers' exercise capacity has only been partially studied. To study lung function, exercise capacity, and identify factors associated with functional impairment. In a cross-sectional study of 193 current miners from Ametista do Sul, Rio Grande do Sul, Brazil, medical and occupational data were collected. The diagnosis of silicosis was established by the history of dust exposure and chest radiographic findings. All workers performed a spirometry and a 6-minute walk test (6MWT). Of the sample 51 (26.4%) had silicosis. Time working in mine was 14.7±8.7 years. Spirometry showed a normal, restrictive or obstructive ventilatory pattern in 75.1 %, 13 % and 9.3 % of the workers, respectively. The diagnosis of silicosis and length of time working in mining negatively affected lung function, although exercise capacity was preserved. In the multivariate analysis, time working in mining, diagnosis of silicosis and education remained significant for forced expiratory volume in one second (FEV1; r = 0.60; r2 = 0.36; p < 0.001) and age and height for distance in 6MWT (r = 0.66; r2 = 0.43; p < 0.001). Our results show impaired lung function and preserved exercise capacity in current mineworkers exposed to silica. Length of time working in mining, presence of silicosis and lower education were factors associated with reduced lung function.

Persistent East Equatorial Pacific Carbon Storage at the Middle Pleistocene Transition

AbstractThe Middle Pleistocene Transition (MPT, ~641–920 ka) represents a period of the Quaternary climate when, in the absence of substantial changes in orbital forcing, the climate progressively shifted to the 100 ka asymmetrical glacial–interglacial cyclicity characterizing the current climate. The causes of this change remain still uncertain but several lines of evidence suggested the carbon storage of the deep ocean played a relevant role. Here we evaluate the contribution of the eastern deep tropical Pacific to the global ocean carbon sequestration and storage between 760 and 1,040 ka. We present multi‐proxy records for export production and the redox environment at the seabed from Ocean Drilling Program Site 1242 located in the deep East Equatorial Pacific. Our data indicate the development of suboxic bottom waters during early marine isotopic stage (MIS) 23 and glacial MIS 22, suggesting the capture and storage of respired carbon. Redox‐sensitive elements suggest the progressive oxygenation of the deep ocean initiated at the end of the glacial MIS 22, continued across deglaciation and ended with the accomplishment of full interglacial MIS 21. We describe this pattern as a “less complete deglacial ventilation” in that it differs from the mid‐late Pleistocene Pacific deep ocean ventilation pattern which occurs during deglaciations. The ventilation of the deep Pacific Ocean extending beyond deglaciation might have contributed to a persistent deep ocean carbon sequestration, which might have resulted in lowered atmospheric CO2 values that could have influenced the internal response of the climate system contributing to the development of the 100 ka climate variability.

Brainstem inflammation modulates the ventilatory pattern and its variability after acute lung injury in rodents.

Compared with sham rats, rats a week after acute lung injury (ALI) express more pro-inflammatory cytokines in their brainstem respiratory control nuclei, exhibit a higher respiratory frequency (fR) and breathe with a more predictable pattern. These characteristics of the respiratory pattern persist in insitu preparations even after minimizing pulmonary and chemo-afferent inputs. Interleukin (IL)-1β microinjected in the nucleus tractus solitarii increases fR and the predictability of the ventilatory pattern similar to rats with ALI. Intracerebroventricular infusion of indomethacin, an anti-inflammatory drug, mitigates the effect of ALI on fR and ventilatory pattern variability. We conclude that changes in the ventilatory pattern after ALI result not only from sensory input due to pulmonary damage and dysfunction but also from neuro-inflammation. Acute lung injury (ALI) increases respiratory rate (fR) and ventilatory pattern variability (VPV), but also evokes peripheral and central inflammation. We hypothesized that central inflammation has a role in determining the ventilatory pattern after ALI. In rat pups, we intratracheally injected either bleomycin to induce ALI or saline as a sham control. One week later, we recorded the ventilatory pattern of the rat pups using flow-through plethysmography, then formed insitu preparations from these pups and recorded their 'fictive' patterns from respiratory motor nerves. Compared with the ventilatory pattern of the sham rat pups, injured rat pups had increased fR and predictability. Surprisingly, the fictive patterns of the insitu preparations from ALI pups retained these characteristics despite removing their lungs to eliminate pulmonary sensory inputs and perfusing them with hyperoxic artificial cerebral spinal fluid to minimize peripheral chemoreceptor input. Histological processing revealed increased immunoreactivity of the pro-inflammatory cytokine Interleukin-1β (IL-1β) in the nucleus tractus solitarii (nTS) from ALI but not sham rats. In subsequent experiments, we microinjected IL-1β in the nTS bilaterally in anaesthetized naïve adult rats, which increased fR and predictability of ventilatory pattern variability (VPV) after 2h. Finally, we infused indomethacin intracerebroventricularly during the week of survival after ALI. This did not affect sham rats, but mitigated changes in fR and VPV in ALI rats. We conclude that neuro-inflammation has an essential role in determining the ventilatory pattern of ALI rats.

Coupling air temperature records and gravimetric data to interpret ventilation patterns in a Mediterranean karstic system (Nerja-Pintada caves, southern Spain)

Microclimate and geophysical studies are commonly applied to the characterization of karst systems although they are usually used separately. The main purpose of this manuscript is to show how the analysis of the data from both these research methods is a useful tool in the characterization of karst systems and we present the analysis of a specific case study: the Nerja- Pintada caves system. The joint analysis of the Nerja Cave and external air data (mainly temperatures) and the pre-existing gravimetric data of its surroundings (residual gravity anomaly map) have allowed us: 1) to postulate the existence of an unknown great cavity located near to the Nerja Cave and with direct influence in its ventilation and 2) to propose a new model of the Nerja-Pintada caves ventilation based on the changing connection between a “main cavity” system (Nerja Cave), with basically a transmissive function of airflows and an “annex cavities” sub-system, with different functioning as far as the airflow is concerned: transmissive in the case of Pintada Cave and capacitive in the case of the geophysically-located cave.

Bi-Level ventilation decreases pulmonary shunt and modulates neuroinflammation in a cardiopulmonary resuscitation model.

BackgroundOptimal ventilation strategies during cardiopulmonary resuscitation are still heavily debated and poorly understood. So far, no convincing evidence could be presented in favour of outcome relevance and necessity of specific ventilation patterns. In recent years, alternative models to the guideline-based intermittent positive pressure ventilation (IPPV) have been proposed. In this randomized controlled trial, we evaluated a bi-level ventilation approach in a porcine model to assess possible physiological advantages for the pulmonary system as well as resulting changes in neuroinflammation compared to standard measures.MethodsSixteen male German landrace pigs were anesthetized and instrumented with arterial and venous catheters. Ventricular fibrillation was induced and the animals were left untreated and without ventilation for 4 minutes. After randomization, the animals were assigned to either the guideline-based group (IPPV, tidal volume 8–10 ml/kg, respiratory rate 10/min, FiO21.0) or the bi-level group (inspiratory pressure levels 15–17 cmH2O/5cmH2O, respiratory rate 10/min, FiO21.0). Mechanical chest compressions and interventional ventilation were initiated and after 5 minutes, blood samples, including ventilation/perfusion measurements via multiple inert gas elimination technique, were taken. After 8 minutes, advanced life support including adrenaline administration and defibrillations were started for up to 4 cycles. Animals achieving ROSC were monitored for 6 hours and lungs and brain tissue were harvested for further analyses.ResultsFive of the IPPV and four of the bi-level animals achieved ROSC. While there were no significant differences in gas exchange or hemodynamic values, bi-level treated animals showed less pulmonary shunt directly after ROSC and a tendency to lower inspiratory pressures during CPR. Additionally, cytokine expression of tumour necrosis factor alpha was significantly reduced in hippocampal tissue compared to IPPV animals.ConclusionBi-level ventilation with a constant positive end expiratory pressure and pressure-controlled ventilation is not inferior in terms of oxygenation and decarboxylation when compared to guideline-based IPPV ventilation. Additionally, bi-level ventilation showed signs for a potentially ameliorated neurological outcome as well as less pulmonary shunt following experimental resuscitation. Given the restrictions of the animal model, these advantages should be further examined.

Angiotensin II-Type I Receptor Antagonism Does Not Influence the Chemoreceptor Reflex or Hypoxia-Induced Central Sleep Apnea in Men.

Components of the renin-angiotensin system (RAS) situated within the carotid body or central nervous system may promote hypoxia-induced chemoreceptor reflex sensitization or central sleep apnea (CSA). We determined if losartan, an angiotensin-II type-I receptor (AT1R) antagonist, would attenuate chemoreceptor reflex sensitivity before or after 8 h of nocturnal hypoxia, and consequently CSA severity. In a double-blind, randomized, placebo-controlled, crossover protocol, 14 men (age: 25 ± 2 years; BMI: 24.6 ± 1.1 kg/m2; means ± SEM) ingested 3 doses of either losartan (50 mg) or placebo every 8 h. Chemoreceptor reflex sensitivity was assessed during hypoxic and hyperoxic hypercapnic ventilatory response (HCVR) tests and during six-20s hypoxic apneas before and after 8 h of sleep in normobaric hypoxia (FIO2 = 0.135). Loop gain was assessed from a ventilatory control model fitted to the ventilatory pattern of CSA recorded during polysomnography. Prior to nocturnal hypoxia, losartan had no effect on either the hyperoxic (losartan: 3.6 ± 1.1, placebo: 4.0 ± 0.6 l/min/mmHg; P = 0.9) or hypoxic HCVR (losartan: 5.3 ± 1.4, placebo: 5.7 ± 0.68 l/min/mmHg; P = 1.0). Likewise, losartan did not influence either the hyperoxic (losartan: 4.2 ± 1.3, placebo: 3.8 ± 1.1 l/min/mmHg; P = 0.5) or hypoxic HCVR (losartan: 6.6 ± 1.8, placebo: 6.3 ± 1.5 l/min/mmHg; P = 0.9) after nocturnal hypoxia. Cardiorespiratory responses to apnea and participants’ apnea hypopnea indexes during placebo and losartan were similar (73 ± 15 vs. 75 ± 14 events/h; P = 0.9). Loop gain, which correlated with CSA severity (r = 0.94, P < 0.001), was similar between treatments. In summary, in young healthy men, hypoxia-induced CSA severity is strongly associated with loop gain, but the AT1R does not modulate chemoreceptor reflex sensitivity before or after 8 h of nocturnal hypoxia.

Effect of Subcutaneous Insulin on Spirometric Maneuvers in Patients with Type 1 Diabetes: A Case-Control Study.

In order to compare spirometric maneuvers in adults according to the presence of type 1 diabetes, a case-control study including 75 patients with type 1 diabetes and 75 controls matched by sex, age, and body mass index were designed. In addition, 75 patients with type 1 diabetes were added to examine the potential the impact of subcutaneous insulin therapy on pulmonary function. Lung function measurements were assessed according to the global initiative for chronic obstructive lung disease guidelines. Basal insulin included long-acting insulin analogues and the delivered background insulin in patients with pump therapy. Bolus insulin included rapid-acting insulin analogues and the delivered insulin to cover postprandial hyperglycemias. Patients with type 1 diabetes showed lower spirometric values in comparison to the control group, together with a higher prevalence of forced expiratory volume in the first second (FEV1) <80% (10.7% vs. 2.7%, p = 0.044) and restrictive ventilatory pattern (10.7% vs. 0%, p = 0.006) The dose of basal insulin (U/kg/day) showed a negative correlation with forced vital capacity (FVC) (r = −0.205, p = 0.012) and FEV1 (r = −0.182, p = 0.026). The optimal cut-off value for identifying patients with a restrictive spirometric pattern was 0.5 U/kg/day of basal insulin. Additionally, basal insulin (U/kg/day) independently predicted the presence of both a restrictive spirometric pattern (OR = 77.1 (3.2 to 1816.6), p = 0.007) and an abnormal FEV1 (OR = 29.9 (1.5 to 562.8), p = 0.023). In patients with type 1 diabetes, higher basal insulin dosage seems to be related with an impairment of pulmonary function.

AVATREE: An open-source computational modelling framework modelling Anatomically Valid Airway TREE conformations.

This paper presents AVATREE, a computational modelling framework that generates Anatomically Valid Airway tree conformations and provides capabilities for simulation of broncho-constriction apparent in obstructive pulmonary conditions. Such conformations are obtained from the personalized 3D geometry generated from computed tomography (CT) data through image segmentation. The patient-specific representation of the bronchial tree structure is extended beyond the visible airway generation depth using a knowledge-based technique built from morphometric studies. Additional functionalities of AVATREE include visualization of spatial probability maps for the airway generations projected on the CT imaging data, and visualization of the airway tree based on local structure properties. Furthermore, the proposed toolbox supports the simulation of broncho-constriction apparent in pulmonary diseases, such as chronic obstructive pulmonary disease (COPD) and asthma. AVATREE is provided as an open-source toolbox in C++ and is supported by a graphical user interface integrating the modelling functionalities. It can be exploited in studies of gas flow, gas mixing, ventilation patterns and particle deposition in the pulmonary system, with the aim to improve clinical decision making.

Role of ventilatory control instability in children with sleep-disordered breathing.

The contribution of non-anatomical factors, such as ventilatory control instability (i.e. LG), to the pathogenesis of obstructive SDB in children is unclear. Therefore, we aimed to identify the relationship between LG and severity of SDB, demographic, anthropometric and anatomical characteristics in a clinically representative cohort of children. Children (aged 3-18 years) with various severities of SDB (n = 110) and non-snoring controls (n = 36) were studied. Children were grouped according to their OAHI. Anthropometric and upper airway anatomical characteristics were measured. Spontaneous sighs were identified on polysomnography and LG, a measure of the sensitivity of the negative feedback loop that controls ventilation, was estimated by fitting a mathematical model of ventilatory control to the post-sigh ventilatory pattern. There was no difference in LG between controls and any of the SDB severity groups. However, LG was significantly lower in children with larger tonsils (tonsil grade 4) compared with children with smaller tonsils (tonsil grade 1) (median LG (range): 0.25 (0.20-0.42) vs 0.32 (0.25-0.44); P = 0.009) and in children with a modified Mallampati score of class III/IV compared with class I (0.28 (0.24-0.33) vs 0.37 (0.27-0.44); P = 0.009). A direct relationship was not found between the severity of paediatric SDB and LG. However, an altered ventilatory control sensitivity may contribute to SDB in a subgroup of children depending on their degree of anatomical compromise of the airway.