Impaired Pulmonary Gas Exchange Research Articles

An underrecognized phenotype of pulmonary emphysema with marked pulmonary gas exchange but with mild or moderate airway obstruction

In patients with pulmonary emphysema and mild to moderate airflow limitation, one does not expect the features marked exertional dyspnea and hypoxemia as well as a profound decrease in diffusing capacity of the lung for carbon monoxide (DLCO). Here we describe this phenotype and its prognosis. From our database, we retrospectively selected cases associating emphysema, exertional breathlessness, O2 requirement at least upon exercise, forced expiratory volume in 1 sec (FEV1) ≥ 50% predicted, and DLCO ≤ 50% predicted, without associated combined pulmonary fibrosis and emphysema, right-to-left shunt, or severe pulmonary hypertension. Over a 12-year period, we identified 16 patients with emphysema and the above presentation. At the initial evaluation, the median age was 62 years (interquartile range 53.8–68.9). The median FEV1 and DLCO% predicted and mean pulmonary artery pressure were 86 (65–95)%, 38 (31–41)%, and 20 (17–25) mm Hg, respectively. On room air, the median arterial partial pressure of oxygen and partial pressure of carbon dioxide in arterial blood were 63.5 (55.8–69) mm Hg and 34.5 (31–36) mm Hg with increased median alveolar-arterial oxygen difference (46 [39–51] mm Hg). After the initial evaluation, the respiratory condition worsened in 13 of 14 (92.8%) patients with one or more re-evaluations (median follow-up 2.6 [0.9–5.8] years). In 12, lung transplantation was considered. Four patients died after 5.8, 5.7, 7.1, and 0.8 years of follow-up, respectively. We describe an underrecognized phenotype of pulmonary emphysema featuring a particular profile characterized by marked exertional dyspnea, impaired pulmonary gas exchange with low DLCO and marked oxygen desaturation at least on exercise but with mild or moderate airway obstruction.

Deciphering Alveolo-Capillary Gas Transfer Disturbances in Patients Recovering from COVID-19 Lung Disease.

Impaired lung gas exchange is commonly seen in patients with pulmonary involvement related to SARS-CoV-2 acute infection or post-acute COVID-19 syndrome (PACS). The primary aim of our study was to assess lung gas transfer, measuring the pulmonary diffusion capacity for nitric oxide (DLNO) and carbon monoxide (DLCO) in all COVID-19 patients. Our secondary aim was to decipher the respective roles of perturbed lung membrane conductance (DM) and reduced pulmonary capillary volume (VC) in patients with impaired lung gas exchange. From May to October 2020, we measured DLNO-DLCO in 118 patients during their post-COVID-19 period (4.6 months after infection) to decipher alveolo-capillary gas transfer disturbances. DLNO-DLCO measurement was also performed in 28 healthy non-smokers as controls. Patients were classified into three groups according to the severity (mild, moderate, and severe) of acute COVID-19 infection. Patients with mild COVID-19 had normal lung volumes and airways expiratory flows but impaired pulmonary gas exchange, as shown by the significant decreases in DLNO, DLCO, DM, and VC as compared with controls. VC was significantly impaired and the DLNO/DLCO ratio was increased in patients with moderate (n = 4, 11%) and severe COVID-19 (n = 23, 49%). Abnormal membrane conductance was also seen in all three groups of post-COVID-19 patients. These findings suggest a persistent alveolo-capillary gas transfer defect, implying not only reduced membrane conductance but also abnormal pulmonary vascular capacitance in all PACS patients, even those with a milder form of COVID-19 infection.

Impact of Bronchoscopic Lung Volume Reduction with Valves on the Pulmonary Gas Exchange.

Introduction: Bronchoscopic lung volume reduction (BLVR) with endobronchial valves has been shown to be a safe and effective treatment for patients with severe lung emphysema. Previous studies have reported a benefit in pulmonary function, exercise capacity, and quality of life after BLVR-treatment. The effect of BLVR with valves on the pulmonary gas exchange and its association with clinical outcomes has not been analyzed to date. The primary goal of this study was to investigate the impact of BLVR on the pulmonary gas exchange and the impact of the target lobe selection in patients with discordant target lobes in high-resolution computed tomography (HRCT) scan and perfusion scan on the pulmonary gas exchange and clinical outcomes. Methods: In this single-center study, we retrospectively analyzed pulmonary function tests, 6-min-walk-tests, HRCT scans, perfusion scans, and blood gas analyses in 77 patients over the course of 6 months following BLVR treatment. Results: We observed that complete lobar occlusion with bronchoscopic valves leads to a transient impairment of pulmonary gas exchange. Despite this, an overall positive clinical outcome could be shown in patients treated with endobronchial valves. If the target lobe selection based on HRCT and perfusion scans is discrepant, a selection based on the HRCT scan tends to be associated with a better outcome than a selection based on the perfusion scan. Conclusions: Complete lobar occlusion with bronchoscopic valves leads to a transient impairment of pulmonary gas exchange but nevertheless results in an overall positive clinical outcome.

Pulmonary function testing in preoperative high-risk patients

BackgroundPostoperative respiratory failure is the most frequent complication in postsurgical patients. The purpose of this study is to assess whether pulmonary function testing in high-risk patients during preoperative assessment detects previously unknown respiratory impairments which may influence patient outcomes.MethodsA targeted patient screening by spirometry and the measurement of the diffusing capacity of the lung for carbon monoxide (DLCO) was implemented in the anesthesia department of a tertiary university hospital. Patients of all surgical disciplines who were at least 75 years old or exhibited reduced exercise tolerance with the metabolic equivalent of task less than four (MET < 4) were examined. Clinical characteristics, history of lung diseases, and smoking status were also recorded. The statistical analysis entailed t-tests, one-way ANOVA, and multiple linear regression with backward elimination for group comparisons.ResultsAmong 256 included patients, 230 fulfilled the test quality criteria. Eighty-one (35.2%) patients presented obstructive ventilatory disorders, out of which 65 were previously unknown. 38 of the newly diagnosed obstructive disorders were mild, 18 moderate, and 9 severe. One hundred forty-five DLCO measurements revealed 40 (27.6%) previously unknown gas exchange impairments; 21 were mild, 17 moderate, and 2 severe. The pulmonary function parameters of forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), and DLCO were significantly lower than the international reference values of a healthy population. Patients with a lower ASA class and no history of smoking exhibited higher FVC, FEV1, and DLCO values. Reduced exercise tolerance with MET < 4 was strongly associated with lower spirometry values.ConclusionsOur screening program detected a relevant number of patients with previously unknown obstructive ventilatory disorders and impaired pulmonary gas exchange. This newly discovered sickness is associated with low metabolic equivalents and may influence perioperative outcomes. Whether optimized management of patients with previously unknown impaired lung function leads to a better outcome should be evaluated in multicenter studies.Trial registrationGerman Registry of Clinical Studies (DRKS00029337), registered on: June 22nd, 2022.

Influence of the chest wall on respiratory function at birth in near-term lambs.

Airway liquid is cleared into lung tissue after birth, which becomes edematous and forces the chest wall to expand to accommodate both the cleared liquid and incoming air. This study investigated how changing chest wall mechanics affects respiratory function after birth in near-term lambs with different airway liquid volumes. Surgically instrumented near-term lambs (139 ± 2 days) were randomized into Control (n = 7) or Elevated Liquid (EL; n = 6) groups. Control lambs had lung liquid drained to simulate expected volumes following vaginal delivery. EL lambs had airway liquid drained and 30 mL/kg liquid returned to simulate expected airway liquid volumes after elective cesarean section. Lambs were delivered, transferred to a Perspex box, and ventilated (30 min). Pressure in the box was adjusted to apply positive (7-8 cmH2O above atmospheric pressure) or negative (7-8 cmH2O below atmospheric pressure) pressures for 30 min before pressures were reversed. External negative pressures expanded the chest wall, reduced chest wall compliance (CCW) and increased lung compliance (CL) in Control and EL lambs. External positive pressures compressed the chest wall, increased CCW and reduced CL in Control and EL lambs. External negative pressure improved pulmonary oxygen exchange, reducing the alveolar-arterial difference in oxygen (AaDO2) by 69 mmHg (95% CI [13, 125]; P = 0.016) in Control lambs and by 300 mmHg (95% CI [233, 367]; P < 0.001) in EL lambs. In contrast, external positive pressures impaired pulmonary gas exchange, increasing the AaDO2 by 179 mmHg (95% CI [73, 285]; P = 0.002) in Control and by 215 mmHg (95% CI [89, 343]; P < 0.001) in EL lambs. The application of external thoracic pressures influences respiratory function after birth.NEW & NOTEWORTHY This study investigated how changes in chest wall mechanics influence respiratory function after birth. Our data indicate that the application of continuous external subatmospheric pressure greatly improves respiratory function in near-term lambs with respiratory distress, whereas external positive pressures impair respiratory function. Our findings indicate that, during neonatal resuscitation at birth, the forces applied to the chest wall should not be ignored as they can have a major impact on neonatal respiratory function.

Evaluation of intrapulmonary arteriovenous anastomoses before and after oxygen supplementation, using transthoracic agitated saline contrast echocardiography in rescued Korean raccoon dogs.

Intrapulmonary arteriovenous anastomoses (IPAVAs) are defined as relatively large, dynamic shunt vessels that connect the pulmonary arterial and venous systems, thereby bypassing the pulmonary capillary system. IPAVAs lower elevated pulmonary arterial pressure; however, the presence of the shunt can result in impaired pulmonary gas exchange and paradoxical embolism. Furthermore, the prevalence and effects of IPAVAs in raccoon dogs remain unknown. This study aimed to determine the prevalence of IPAVA among rescued Korean raccoon dogs and evaluate the changes in IPAVA following oxygen supplementation. Nineteen raccoon dogs rescued by the Jeonbuk Wildlife Centre between August 2022 and December 2023 were subjected to echocardiography. Sixteen healthy and three abnormal raccoon dogs were subjected to transthoracic agitated saline contrast echocardiography (bubble study) based on the echocardiography results. IPAVA was considered to be present if the left heart contrast was visualised after four cardiac cycles following the visualisation of the first right heart contrast. Bubble scores (BS0-5) were assigned based on the maximum number of microbubbles observed in the left ventricular lumen per frame of the ultrasound image. BS was assigned before and after supplementation with 100% oxygen for 5 min. IPAVA was detected in 12 of the 16 healthy raccoon dogs at rest (75%). The BS of the 15 IPAVA-positive raccoon dogs ranged from 1 to 4 points (BS1, 1; BS2, 4; BS3, 8; and BS4, 2). Blood flow through the IPAVA (QIPAVA) was reduced or absent in the 15 IPAVA-positive raccoon dogs after supplementation with 100% oxygen (BS0, 11; BS2, 4). Moreover, BS of the IPAVA showed a significant correlation with the cardiac output per body weight (BW). The prevalence of IPAVA in healthy raccoon dogs at rest was 75%. Adequate oxygen supplementation was found to be effective in reducing QIPAVA, which may help prevent potential negative factors such as pulmonary gas exchange impairments and paradoxical embolism that can occur with IPAVA.

The Plastic Interplay between Lung Regeneration Phenomena and Fibrotic Evolution: Current Challenges and Novel Therapeutic Perspectives.

Interstitial lung diseases (ILDs) are a heterogeneous group of pulmonary disorders characterized by variable degrees of inflammation, interstitial thickening, and fibrosis leading to distortion of the pulmonary architecture and gas exchange impairment. Among them, idiopathic pulmonary fibrosis (IPF) displays the worst prognosis. The only therapeutic options consist of the two antifibrotic drugs, pirfenidone and nintedanib, which limit fibrosis progression but do not reverse the lung damage. The shift of the pathogenetic paradigm from inflammatory disease to epithelium-derived disease has definitively established the primary role of type II alveolar cells, which lose their epithelial phenotype and acquire a mesenchymal phenotype with production of collagen and extracellular matrix (EMC) deposition. Some predisposing environmental and genetic factors (e.g., smoke, pollution, gastroesophageal reflux, variants of telomere and surfactant genes) leading to accelerated senescence set a pro-fibrogentic microenvironment and contribute to the loss of regenerative properties of type II epithelial cells in response to pathogenic noxae. This review provides a complete overview of the different pathogenetic mechanisms leading to the development of IPF. Then, we summarize the currently approved therapies and the main clinical trials ongoing. Finally, we explore the potentialities offered by agents not only interfering with the processes of fibrosis but also restoring the physiological properties of alveolar regeneration, with a particular focus on potentialities and concerns about cell therapies based on mesenchymal stem cells (MSCs), whose anti-inflammatory and immunomodulant properties have been exploited in other fibrotic diseases, such as graft versus host disease (GVHD) and COVID-19-related ARDS.

Diagnosing disorders of respiratory mechanics in refractory workers

Introduction. The current decrease in occupational exposures complicates expert examination of the link between job and disease, thus requiring the use of more sensitive and high-tech diagnostic techniques. In addition, a low incidence rate of occupational diseases against the background of poor working conditions indicates a possible increase in the incidence of “hidden” occupational diseases mimicking common non-communicable diseases.&#x0D; The purpose of our study was to assess the respiratory function in refractory workers using body plethysmography and measurements of the diffusing capacity of the lungs.&#x0D; Materials and methods: One hundred six male workers aged of 45.62±0.8 years, all engaged in refractory manufacturing for the average of 15.5±0.88 years and at risk of dust-related respiratory diseases, were examined in our Occupational Health Center within the regular health check-up.&#x0D; Results. The results of body plethysmography (a pulmonary function test) showed a decrease in the FEV1/FVC ratio, i.e. the ratio of the forced expiratory volume over the first one second to the forced vital capacity of the lungs, to the group average of 77.87±0.76% of the normal value. We also observed increased bronchial resistance during exhalation and total bronchial resistance in 65% and 50.9% of the workers, respectively. We registered a decreased transfer factor in the examined subjects with the group average of 73.9±1.37%. Neither chest X-ray nor CT scan showed significant changes in most of workers. Signs of emphysema were registered in 5.7% of those examined cases. No significant differences in the prevalence of obstructive disorders were found between smoking and non-smoking workers. Bronchial obstructive syndrome in combination with impaired pulmonary gas exchange and respiratory muscle fatigue was registered &#x0D; in 16 workers (15%), thus necessitating specific therapy to interfere with disease progression.&#x0D; Limitations. Our findings cannot be extrapolated to the workforce as a whole, since only men included in the study cohort.&#x0D; Conclusions. Indicators of the diffusing capacity of the lungs, which simultaneously reflect both pulmonary ventilation and perfusion, in combination with findings of body plethysmography and chest CT scan, can provide important information about functional changes in the respiratory system. Early diagnosis of bronchial obstructive syndrome allows timely beginning therapy and prevention of disease progression.

Estimating cardiopulmonary fitness with a new sampling technology in patients with rheumatoid arthritis-associated interstitial lung disease.

Although peak oxygen uptake (VO2peak ) is one of the most important measures in clinical practice, the high cost and time consumption have led to the search for simpler devices and the development of the estimating cardiopulmonary fitness (eCPF) equation. Since the lungs are one of the sites most affected by rheumatoid arthritis (RA), this study aimed to create a predictive equation for VO2peak obtained by simple sampling technology in women with RA-associated interstitial lung disease (RA-ILD). This cross-sectional study evaluated 47 women with RA-ILD. The participants underwent the following evaluations: computed tomography (CT); evaluation of disease activity through the Clinical Disease Activity Index (CDAI); measurement of physical function using the Health Assessment Questionnaire disability index (HAQ-DI); pulmonary function testing, including spirometry, diffusing capacity for carbon monoxide (DlCO ), nitrogen single-breath washout (N2 SBW) test, and impulse oscillometry; and cardiopulmonary exercise testing (CPET) using FitMate™. VO2peak was correlated with age (r=-0.550, p<0.0001), rheumatoid factor (r=-0.443, p=0.002), anti-cyclic citrullinated peptide antibodies (r= -0.410, p=0.004), CDAI (r=-0.462, p=0.001), HAD-DI (r=-0.486, p=0.0005), forced vital capacity (r=0.491, p=0.0004), DlCO (r=0.621, p<0.0001), phase III slope of N2 SBW (r=-0.647, p<0.0001), resonance frequency (Fres , r=-0.717, p<0.0001), integrated low-frequency reactance (r=-0.535, p=0.0001), and the inhomogeneity of respiratory system resistance between 4 and 20Hz (r=-0.631, p<0.0001). In the CT examination, patients with extensive ILD had significantly lower VO2peak than patients with limited ILD (p<0.0001). In the stepwise forward regression analysis, Fres , DlCO and age explained 61% of the VO2peak variability. As assessed by CPET, women with RA-ILD show reduced cardiopulmonary fitness, which can be explained at least in part by the presence of small airway disease, deterioration of pulmonary gas exchange, and advanced age. These associations of pulmonary variables with eCPF may be clinically important and support the use of the eCPF equation to improve patient outcomes.

Ventilatory response and stability of oxygen saturation during a hypoxic challenge in very preterm infants.

Preterm infants have immature control of breathing and impaired pulmonary gas exchange. We hypothesized that infants with bronchopulmonary dysplasia (BPD) have a blunted ventilatory response and peripheral oxygen saturation (SpO2 ) instability during a hypoxic challenge. We evaluated the response to hypoxia in 57 very preterm infants (38 no BPD, 10 mild BPD, 9 moderate-to-severe BPD) at 36 weeks' postmenstrual age. The fraction of inspired oxygen (FI O2 ) was reduced stepwise at 5-min intervals to achieve peripheral SpO2 between 86% and 95%. The lowest permissible FI O2 and SpO2 were 0.14% and 86%. We recorded SpO2 , FI O2 , and the respiratory signal (respiratory inductive plethysmography). We calculated respiratory rate (RR), tidal volume (VT ), minute ventilation (VE ), and respiratory drive (ratio between VT and inspiratory time, VT /TI ). SpO2 variability was expressed as the interquartile range (IQR). FI O2 was reduced from a median (Q1, Q3) of 0.21 (0.21, 0.21) to 0.17 (0.17, 0.18). We observed a marked individual variability in the ventilatory response to the hypoxic challenge, regardless of BPD severity. At the lowest permissible FI O2 , 37(65%) infants reduced their VE , and 20 (35%) increased minute ventilation; 20infants (35%) developed periodic breathing associated with increased SpO2 IQR and lower SpO2 minima, and 16 (28%) exhibited an oscillatory pattern in VE and SpO2 without end-expiratory pauses, regardless of BPD severity. In very preterm infants, a mild hypoxic challenge reduced ventilation, increased SpO2 variability and periodic breathing regardless of BPD severity.

Intrapulmonary shunt and alveolar dead space in a cohort of patients with acute COVID-19 pneumonitis and early recovery.

Pathological evidence suggests that coronavirus disease 2019 (COVID-19) pulmonary infection involves both alveolar damage (causing shunt) and diffuse microvascular thrombus formation (causing alveolar dead space). We propose that measuring respiratory gas exchange enables detection and quantification of these abnormalities. We aimed to measure shunt and alveolar dead space in moderate COVID-19 during acute illness and recovery. We studied 30 patients (22 males; mean±sd age 49.9±13.5 years) 3-15 days from symptom onset and again during recovery, 55±10 days later (n=17). Arterial blood (breathing ambient air) was collected while exhaled oxygen and carbon dioxide concentrations were measured, yielding alveolar-arterial differences for each gas (P A-aO2 and P a-ACO2 , respectively) from which shunt and alveolar dead space were computed. For acute COVID-19 patients, group mean (range) for P A-aO2 was 41.4 (-3.5-69.3) mmHg and for P a-ACO2 was 6.0 (-2.3-13.4) mmHg. Both shunt (% cardiac output) at 10.4% (0-22.0%) and alveolar dead space (% tidal volume) at 14.9% (0-32.3%) were elevated (normal: <5% and <10%, respectively), but not correlated (p=0.27). At recovery, shunt was 2.4% (0-6.1%) and alveolar dead space was 8.5% (0-22.4%) (both p<0.05 versus acute). Shunt was marginally elevated for two patients; however, five patients (30%) had elevated alveolar dead space. We speculate impaired pulmonary gas exchange in early COVID-19 pneumonitis arises from two concurrent, independent and variable processes (alveolar filling and pulmonary vascular obstruction). For most patients these resolve within weeks; however, high alveolar dead space in ∼30% of recovered patients suggests persistent pulmonary vascular pathology.

Obese patients with long COVID-19 display abnormal hyperventilatory response and impaired gas exchange at peak exercise.

Aim: To analyze the impact of obesity on cardiopulmonary response to exercise in people with chronic post-coronavirus disease 2019 (COVID-19) syndrome. Patients & methods: Consecutive subjects with chronic post-COVID syndrome 6 months after nonsevere acute infection were included. All patients received a complete clinical evaluation, lung function tests and cardiopulmonary exercise testing. A total of 51 consecutive patients diagnosed with chronic post-COVID-19 were enrolled in this study. Results: More than half of patients with chronic post-COVID-19 had a significant alteration in aerobic exercise capacity (VO2peak) 6 months after hospital discharge. Obese long-COVID-19 patients also displayed a marked reduction of oxygen pulse (O2pulse). Conclusion: Obese patients were more prone to have pathological pulmonary limitation and pulmonary gas exchange impairment to exercise compared with nonobese COVID-19 patients.

Brief Report: HIV Is Associated With Impaired Pulmonary Diffusing Capacity Independent of Emphysema.

Background:HIV is associated with accelerated decline in lung function and increased risk for chronic obstructive pulmonary disease (COPD). Recently, there has been growing attention toward the impairment in the diffusing capacity of the lungs for carbon monoxide (DLCO), a marker of pulmonary gas exchange, observed among persons living with HIV. Although increased emphysema can contribute to the DLCO impairment observed, other factors may drive this association.Methods:Using cross-sectional data from the Study of HIV in the Etiology of Lung Disease, we studied the association between HIV and DLCO independent of emphysema. We also analyzed the joint influence of HIV and COPD on DLCO impairment. An analysis was conducted among 339 participants (229 with HIV) with lung function and chest CT imaging data. Multivariable regression models were generated with percent predicted DLCO and odds of DLCO impairment as outcomes.Results:After adjusting for confounders, including emphysema severity, HIV was associated with lower DLCO (β −4.02%; P = 0.020) and higher odds of DLCO impairment (odds ratio 1.93; P = 0.017). Even among those without COPD, HIV was independently associated with lower DLCO (β −3.89%; P = 0.049). Compared with HIV-uninfected participants without COPD, those with both HIV and COPD experienced the greatest impairment in DLCO (β −14.81; P < 0.001).Conclusions:HIV is associated with impaired pulmonary gas exchange independent of emphysema severity. Our data also suggest a potentially additive influence between HIV and COPD on DLCO impairment. Further studies should investigate the other factors, including pulmonary vascular disease, which may contribute to DLCO impairment among persons living with HIV.

TP10.1.12Personal Protective Equipment impairs pulmonary gas exchange causing systemic hypercapnia-hypoxaemia and cerebral hyperperfusion-induced cephalalgia

Abstract Aims To what extent Personal Protective Equipment (PPE) impacts integrated cardiopulmonary-cerebrovascular function has not been examined. The hypothesis tested was that PPE adversely influences pulmonary gas exchange, resulting in systemic hypercapnic-hypoxaemia and cerebral hyperperfusion-induced cephalalgia. Methods Eight male Higher Surgical Trainees (aged 33 ± 2y) participated in a repeated measures crossover study, completing two-hour laparoscopic simulation tasks, on two separate occasions (separate days), once in standard operating attire, and once in full PPE (including FFP3 mask). Results Following two hours of simulation, full PPE (compared with standard operating attire) was associated with increased FICO2 (7.9% (±0.8%) vs. 7.1% (±1.2%); p = 0.025), decreased FIO2 (16.0% (±0.4%) vs. 16.6% (±0.5%); p = 0.011), and decreased peripheral O2 saturation (95% (± 1%) vs. 98% (±1%); p = 0.001). Headaches were reported by three participants in PPE (Chi2 3.692, p = 0.055), and was associated with increased Middle Cerebral Artery flow velocity; 82 (±4) cm/s, compared with 63 (±9) cm/s in the remaining five participants (p = 0.008). Skin temperature increased by 1.3 °C during simulation in PPE (p = 0.001), with an equal mean insensible fluid loss of 300ml under both conditions (p = 0.049). Conclusions Collectively, these findings highlight the integrated cardiopulmonary-cerebrovascular complications associated with PPE-induced impairment in pulmonary gas exchange. Protective countermeasures should be designed to prevent risk to healthcare staff and patients alike.

The Effect of Physical Therapy on Regional Lung Function in Critically Ill Patients.

Early mobilization has become an important aspect of treatment in intensive care medicine, especially in patients with acute pulmonary dysfunction. As its effects on regional lung physiology have not been fully explored, we conceived a prospective observational study (Registration number: DRKS00023076) investigating regional lung function during a 15-min session of early mobilization physiotherapy with a 30-min follow-up period. The study was conducted on 20 spontaneously breathing adult patients with impaired pulmonary gas exchange receiving routine physical therapy during their intensive care unit stay. Electrical impedance tomography (EIT) was applied to continuously monitor ventilation distribution and changes in lung aeration during mobilization and physical therapy. Baseline data was recorded in the supine position, the subjects were then transferred into the seated and partly standing position for physical therapy. Afterward, patients were transferred back into the initial position and followed up with EIT for 30 min. EIT data were analyzed to assess changes in dorsal fraction of ventilation (%dorsal), end-expiratory lung impedance normalized to tidal variation (ΔEELI), center of ventilation (CoV) and global inhomogeneity index (GI index).Follow-up was completed in 19 patients. During exercise, patients exhibited a significant change in ventilation distribution in favor of dorsal lung regions, which did not persist during follow-up. An identical effect was shown by CoV. ΔEELI increased significantly during follow-up. In conclusion, mobilization led to more dorsal ventilation distribution, but this effect subsided after returning to initial position. End-expiratory lung impedance increased during follow-up indicating a slow increase in end-expiratory lung volume following physical therapy.

Surfactant Depletion Combined with Injurious Ventilation Results in a Reproducible Model of the Acute Respiratory Distress Syndrome (ARDS).

Various animal models exist to study the complex pathomechanisms of the acute respiratory distress syndrome (ARDS). These models include pulmo-arterial infusion of oleic acid, infusion of endotoxins or bacteria, cecal ligation and puncture, various pneumonia models, lung ischemia/reperfusion models and, of course, surfactant depletion models, among others. Surfactant depletion produces a rapid, reproducible deterioration of pulmonary gas exchange and hemodynamics and can be induced in anesthetized pigs using repeated lung lavages with 0.9% saline (35 mL/kg body weight, 37 °C). The surfactant depletion model supports investigations with standard respiratory and hemodynamic monitoring with clinically applied devices. But the model suffers from a relatively high recruitability and ventilation with high airway pressures can immediately reduce the severity of the injury by reopening atelectatic lung areas. Thus, this model is not suitable for investigations of ventilator regimes that use high airway pressures. A combination of surfactant depletion and injurious ventilation with high tidal volume/low positive end-expiratory pressure (high Tv/low PEEP) to cause ventilator induced lung injury (VILI) will reduce the recruitability of the resulting lung injury. The advantages of a timely induction and the possibility to perform experimental research in a setting comparable to an intensive care unit are preserved.

Transcutaneous PCO2 -based dead space ventilation at submaximal exercise accurately discriminates healthy controls from patients with chronic obstructive pulmonary disease.

Increased physiological dead space ventilation (VD /VT ) at exercise reflects pulmonary gas exchange impairment and is a sensitive marker of cardio-respiratory disease. VD /VT is typically not measured during routine cardiopulmonary exercise testing (CPET) because its calculation requires arterial blood gas analysis for determination of PaCO2 . Instead, dead space ventilation is indirectly evaluated as a determinant of the ventilation (VE)/VCO2 relationship, which also depends on the PaCO2 set point. We hypothesized that VD /VT calculations based on non-invasive transcutaneous PCO2 (PtcCO2 ) measurement had better diagnostic characteristics than the VE/VCO2 slope for the discrimination of healthy subjects from patients with COPD, a common disease associated with impaired pulmonary gas exchange. Retrospective study of 19 healthy controls and 24 COPD patients who underwent CPET with continuous PtcCO2 monitoring. Areas under receiver operating characteristics curves (AUC) were calculated to assess diagnostic accuracy of CPET measurement for the discrimination of COPD and Controls. The AUC for PtcCO2 -based VD /VT at VT1 (0.977) was significantly higher than for the VE/VCO2 slope (0.660), SpO2 at peak exercise (0.913), decrease in inspiratory capacity (0.719), and ventilatory reserve (0.708). At a threshold of 0.24, the sensitivity and specificity of PtcCO2 -based VD /VT for the discrimination of COPD patients and healthy Controls were 100% and 84%, respectively. All Control subjects had PtcCO2 -based VD /VT ≤0.25. PtcCO2 -based VD /VT was the most accurate measurement to discriminate healthy controls from subjects with COPD, a chronic lung disease associated with altered pulmonary gas exchange. Non-invasive monitoring of PtcCO2 may be useful for routine CPET.

Comparison of CPAP and oxygen therapy for treatment of postoperative hypoxaemia in dogs.

To compare 5cmH2 O of continuous positive airway pressure with oxygen therapy in dogs recovering from general anaesthesia with low SpO2 values. continuous positive airway pressure is more effective than oxygen therapy in restoring normoxaemia (SpO2 ≥95%). Prospectively, dogs recovering from anaesthesia, with SpO2 <95% after extubation (T0), were randomised and treated with continuous positive airway pressure (FiO2 0.21) or oxygen (O2 ; FiO2 0.35-0.40) therapy. Dogs were monitored with SpO2 every 15 minutes for 1hour (T15, T30, T45, T60). Data from normoxaemic dogs (SpO2 >95%) were used as control (CTR). Of the 42 dogs enrolled, 34 completed the study. Eleven dogs were treated with O2 , 10 with continuous positive airway pressure and 13 were CTR. The SpO2 values at T0 were similar in the continuous positive airway pressure and O2 groups and were lower than in the CTR group. At T15, T30, T45 and T60, the SpO2 values in the continuous positive airway pressure group were higher than at T0; these were similar to those of the CTR group at the same time-points. In the O2 group, SpO2 values were significantly higher at T45 and T60 than at T0; 45.5% of dogs became normoxaemic at T45 and the remaining dogs became normoxaemic at T60. The average time to reach normoxaemia in the O2 group (53.1±7.3 minutes) was longer than in the continuous positive airway pressure group (15.0±0.0 minutes). In dogs recovering from general anaesthesia with pulmonary gas exchange impairment, normoxaemia is restored more effectively and rapidly by using continuous positive airway pressure than by oxygen therapy.

The effect of implementing nursing practices to support ventilation among patients with acute respiratory failure on their condition

Abstract Background: Acute respiratory failure is a sudden and life-threatening deterioration in pulmonary gas exchange, resulting in carbon dioxide retention and inadequate oxygenation approximately 50% to 75% of those patients require ICU hospital stays &and mechanical ventilatory support practices longer than 7 days. Aim: This study aimed to evaluate the effect of implementing nursing practices to support ventilation among patients with acute respiratory failure on their condition. Method: Design: A quasi-experimental research design was used to conduct this research. A convenient sample consisted of 120 patients, they were enrolled in the study group (n=60) and the control group (n=60) was admitted to the chest intensive care unit at Assiut University Hospital. A patient assessment sheet, acute respiratory failure Patient outcomes assessment sheet were used for the collection of data. Results: A significant statistical difference (P

Does gallic acid improve cardiac function by attenuation of oxidative stress and inflammation in an elastase-induced lung injury?

Objective(s):Cardiovascular disease has an important role in mortality caused by lung injury. Emphysema is associated with impaired pulmonary gas exchange efficiency and airflow limitation associated with small airway inflammation. The aim was to evaluate the interactions between lung injury, inflammation, and cardiovascular disease. Since gallic acid has antioxidant and anti-inflammatory effects, we hypothesized that gallic acid protects the lung and the related heart dysfunction in elastase-induced lung injury. Materials and Methods:Forty-eight Sprague-Dawley male rats were randomly divided into six groups: Control, Porcine pancreatic elastase (PPE) , PPE+GA, and 3 groups for different doses of gallic acid (GA 7.5, GA 15, GA 30 mg/kg). PPE was injected intra-tracheally on days 1 and 10 of the test. In each group, electrocardiography, hemodynamic parameters, oxidative stress, and bronchoalveolar lavage fluid were examined.Results:PPE administration showed a decrease in HR and QRS voltage of electrocardiogram parameters, as well as in hemodynamic parameters (P<0.05, P<0.01, and P<0.001) and superoxide dismutase (SOD) (P<0.05). Tumor Necrosis Factor α (TNF-α) (P<0.001), interleukin 6 (IL-6) (P<0.001), interleukin 6 (MDA) (P<0.001), and the total number of white blood cells (P<0.001) showed an increase in PPE groups. Gallic acid preserved the values of hemodynamic properties, oxidative stress, inflammation, and electrocardiogram parameters in comparison to the PPE group.Conclusion:Briefly, this study showed the valuable effect of gallic acid in cardiac dysfunction related to elastase-induced lung injury. These findings suggested that gallic acid, as a natural antioxidant, has a potential therapeutic effect on preventing oxidative stress, inflammation, and subsequent cardiovascular disease.