Alveolar-arterial Oxygen Difference Research Articles

Postoperative pulmonary vascular growth in patients with congenital diaphragmatic hernia

BackgroundPostoperative pulmonary growth in congenital diaphragmatic hernias (CDH) remains unclear. We investigated postoperative pulmonary vascular growth using serial lung perfusion scintigraphy in patients with CDH.MethodsNeonates with left CDH who underwent surgery and postoperative lung perfusion scintigraphy at our institution between 2001 and 2020 were included. Patient demographics, clinical courses, and lung scintigraphy data were retrospectively analyzed by reviewing medical records.ResultsTwenty-one patients with CDH were included. Of these, 10 underwent serial lung scintigraphy. The ipsilateral perfusion rate and median age on the 1st and serial lung scintigraphy were 32% (34 days) and 33% (3.6 years), respectively. Gestational age at prenatal diagnosis (p = 0.02), alveolar–arterial oxygen difference (A-aDO2) at birth (p = 0.007), and preoperative nitric oxide (NO) use (p = 0.014) significantly correlated with the 1st lung scintigraphy. No other variables, including operative approach, were significantly correlated with the 1st or serial scintigraphy findings.All patients improved lung perfusion with serial studies [Difference: + 7.0 (4.3–13.25) %, p = 0.001, paired t-test]. This improvement was not significantly correlated with preoperative A-aDO2 (p = 0.96), NO use (p = 0.28), or liver up (p = 0.90). The difference was significantly larger in patients who underwent thoracoscopic repair than in those who underwent open abdominal repair [+ 10.6 (5.0–17.1) % vs. + 4.25 (1.2–7.9) %, p = 0.042].ConclusionOur study indicated a postoperative improvement in ipsilateral lung vascular growth, which is possibly enhanced by a minimally invasive approach, in patients with CDH.

Apneustic anesthesia ventilation improves pulmonary function in anesthetized bottlenose dolphins (Tursiops truncatus).

Use of mechanical ventilation during general anesthesia is a necessary practice in the anesthetization of small cetaceans as spontaneous ventilation fails to provide adequate gas exchange. Currently available methods of ventilation do not account for the intermittent breathing strategy of representative species within this infraorder of fully aquatic mammals and may have a significant effect on cardiac and respiratory physiology. To understand the impact of mechanical ventilation on cardiopulmonary function in one small species of cetacean, the bottlenose dolphin (Tursiops truncatus), we compared controlled mechanical ventilation (CMV) to a novel ventilation method known as apneustic anesthesia ventilation (AAV). AAV simulates the normal inspiratory breath-hold pattern of dolphins. Ten anesthetic procedures (dental procedure, n = 9; bronchoscopy, n = 2) were performed on nine dolphins (age range: 10-42 years; mean = 32 years; median = 37 years; female = 3, 40%; male = 6, 60%). In a cross-over study design, dolphins were instrumented and randomly assigned to AAV or CMV as the initial mode of ventilation, then switched to the alternate mode. Baseline cardiopulmonary data were collected and again after 30 min on each mode of ventilation. Cardiac index, stroke volume index, systemic vascular resistance, alveolar dead space, alveolar-arterial oxygen tension gradient, arterial oxygen content, oxygen delivery index, and dynamic respiratory system compliance index were calculated at each of the four time points. During AAV, dolphins had higher arterial oxygen tension, higher mean airway pressure, reduced alveolar dead space ventilation and lower alveolar-arterial oxygen difference. Cardiovascular performance was not statistically different between the two modes. Our study suggests AAV, which more closely resembles the conscious intermittent respiratory pattern phenotype of dolphins, improves ventilation and pulmonary function in the anesthetized dolphin. Future studies should evaluate the cardiopulmonary effects of neutral buoyancy and cardiopulmonary sparing drug protocols to reduce the need for hemodynamic support of current protocols.

Respiratory function testing for guiding ventilator mode conversion in congenital diaphragmatic hernia.

For patients with a congenital diaphragmatic hernia, conventional mechanical ventilation (CMV) and high-frequency oscillatory ventilation (HFOV) are used in initial ventilatory management. HFOV has recently been recommended as a rescue therapy; however, we use HFOV for initial ventilation management, with a preoperative challenge test for CMV conversion and respiratory function testing at the time of CMV conversion. We aimed to compare patient characteristics between CMV conversion- and HFOV-preferred treatment groups. Ventilator settings and blood gases were retrospectively evaluated pre- and post-CMV conversion, and respiratory function tests for compliance of the respiratory system (Crs) and for resistance of the respiratory system (Rrs) were performed during the trial to CMV conversion. No differences were observed between the CMV conversion- and HFOV-preferred groups regarding gestational age, birth weight, and observed/expected lung area-to-head circumference ratios. The median Crs (ml/cmH2 O/kg) and Rrs (cmH2 O･kg/L/s) in the CMV conversion- and HFOV-preferred groups was 0.42 versus 0.53 (p = .44) and 467 versus 327 (p = .045), respectively. The pre and posttrial amount of change in blood gas levels and ventilator parameters in the CMV conversion- and HFOV-preferred groups were as follows: mean airway pressure, -2.0 versus 0 cmH2 O; partial pressure of carbon dioxide, 6.1 versus 2.9 Torr; alveolar-arterial oxygen difference, -39.5 versus -50 Torr; and oxygenation index, -1.0 versus -0.6; respectively. Respiratory function tests were useful in tailoring ventilator settings. Patients with high Rrs values responded better to CMV conversion.

Immune disturbance leads to pulmonary embolism in COVID-19 more than classical risk factors: a clinical and histological study

COVID-19 induces endotheliitis and one of the main complications is enhanced coagulation. The incidence of pulmonary embolism (PE) in COVID-19 (CPE) has increased and clinical features for a rigorous analysis still need to be determined. Thus, we evaluated the clinical characteristics in CPE and the immune infiltration that occurred. Between January 1 and December 31, 2021, 38 patients were affected by CPE (9 ICU, 19 males/19 females, 70.18 ± 11.24 years) out of 459 COVID-19 cases. Controls were subjects who were evaluated for PE between January 1 2015, and December 31, 2019 (92 patients, 9 ICU, 48 males/45 females, 69.55 ± 16.59 years). All patients underwent complete physical examination, pulmonary computed tomography, laboratory tests, D-dimer, and blood gas analysis. There were no differences in laboratory tests or D-dimer. In patients with CPE, pO2, alveolar–arterial oxygen difference (A-aDO2), oxygen saturation %, and the ratio between arterial partial pressure of oxygen (PaO2) and fraction of inspired oxygen (FiO2), P/F, were significantly increased. There were no differences in PaCO2. Platelet count was inversely correlated to P/F (r = − 0.389, p = 0.02) but directly to A-aDO2 (r = 0.699, p = 0.001) only in patients with CPE. Histology of lung biopsies (7 CPE/7 controls) of patients with CPE showed an increase in CD15+ cells, HMGB1, and extracellular MPO as a marker of NETosis, while no significant differences were found in CD3+, CD4+, CD8+, and intracellular MPO. Overall, data suggest that CPE has a different clinical setting. Reduced oxygen content and saturation described in Patients with CPE should not be considered a trustworthy sign of disease. Increased A-aDO2 may indicate that CPE involves the smallest vessels as compared to classical PE. The significant difference in NETosis may suggest the mechanism related to thrombi formation.

Hypoxaemia in patients with heart failure and preserved ejection fraction.

It is widely held that heart failure (HF) does not cause exertional hypoxaemia, based upon studies in HF with reduced ejection fraction, but this may not apply to patients with HF and preserved ejection fraction (HFpEF). Here, we characterize the prevalence, pathophysiology, and clinical implications of exertional arterial hypoxaemia in HFpEF. Patients with HFpEF (n = 539) and no coexisting lung disease underwent invasive cardiopulmonary exercise testing with simultaneous blood and expired gas analysis. Exertional hypoxaemia (oxyhaemoglobin saturation <94%) was observed in 136 patients (25%). As compared to those without hypoxaemia (n = 403), patients with hypoxaemia were older and more obese. Patients with HFpEF and hypoxaemia had higher cardiac filling pressures, higher pulmonary vascular pressures, greater alveolar-arterial oxygen difference, increased dead space fraction, and greater physiologic shunt compared to those without hypoxaemia. These differences were replicated in a sensitivity analysis where patients with spirometric abnormalities were excluded. Regression analyses revealed that increases in pulmonary arterial and pulmonary capillary pressures were related to lower arterial oxygen tension (PaO2 ), especially during exercise. Body mass index (BMI) was not correlated with the arterial PaO2 , and hypoxaemia was associated with increased risk for death over 2.8 (interquartile range 0.7-5.5) years of follow-up, even after adjusting for age, sex, and BMI (hazard ratio 2.00, 95% confidence interval 1.01-3.96; p = 0.046). Between 10% and 25% of patients with HFpEF display arterial desaturation during exercise that is not ascribable to lung disease. Exertional hypoxaemia is associated with more severe haemodynamic abnormalities and increased mortality. Further study is required to better understand the mechanisms and treatment of gas exchange abnormalities in HFpEF.

Preoperative AaDO2 as an indicator for physiologic stabilization for repair in infants with congenital diaphragmatic hernia: A multicenter retrospective study

BackgroundAppropriate timing of surgery for neonates with congenital diaphragmatic hernia (CDH) generally has been considered after cardiopulmonary stabilization. However, few reports clearly showed the definition of physiologic stabilization for surgery, while many studies have addressed hours of life for timing of repair. The aim of this study is to elucidate an optimal respiratory condition for repair in CDH. MethodsA retrospective chart review was conducted of 81 isolated CDH patients who were born and treated in three children's hospitals during Jan. 2009 through Sep.2018. To find an optimal respiratory condition for repair, alveolar-arterial oxygen difference (AaDO2) and oxygenation index (OI) right before surgery was investigated, as well as prenatal prognostic factors (observed/expected lung-to-head ratio (o/e LHR) and liver up), patients’ demographics (sex, gestational weeks, birth weight, Apgar scores), and the 30-day survival. Multivariate logistic regression analysis adjusting for the antenatal severity combined with o/e LHR and liver position was performed. ResultsAmong 81patients, 75 patients underwent surgery. The data of AaDO2 and OI right before surgery were available in 73 patients. Among 73 patients, six died in total, and of those, two out of five with extracorporeal membrane oxygenation (ECMO) died. The 30-day mortality in the subset of the fourth quartile of AaDO2 (≥340 mmHg) was significantly higher (odds Ratio (OR) 9.23 95% confidence interval (CI) 1.18072.11 P = 0.03). While mortality of the fourth quartile of OI (≥8) was also higher, it was marginally significant (OR 6.52 95% CI 0.93–45.59 p = 0.06). ConclusionsAaDO2 less than 340 mmHg could be a useful stabilization index for safe surgery in neonates with CDH.

The Role of Serum 1,25-Dihydroxy Vitamin D3 and PCT in Idiopathic Pulmonary Fibrosis.

Biomarkers for the acute exacerbation of idiopathic pulmonary fibrosis (AE-IPF) are urgently needed to provide better patient management. We aimed to investigate whether serum 1,25(OH)2D3 (1,25-dihydroxy vitamin D3) levels predict AE-IPF and whether they could be a potential prognostic biomarker for IPF. This prospective study included 72 patients with IPF (31 with stable IPF and 41 with AE-IPF). All participants were recruited during hospitalisation at Tianjin Chest Hospital and were followed up for at least 12 months. Demographics, comorbidities, arterial blood gas, and serum biochemical profile, radiological features, and anti-fibrotic therapy were evaluated. Serum concentrations of 1,25(OH)2D3 and transforming growth factor beta1 (TGFβ1) were detected using enzyme-linked immunosorbent assay (ELISA). Risk factors for AE-IPF were identified using multivariate analysis. Prognostic factors were assessed using Kaplan-Meier and Cox regression analyses. Baseline values of alveolar-arterial oxygen difference (A-aDO2) (40.85 mmHg vs 29.2 mmHg, p =0.035), white blood cell counts (10.09 ± 4.2×109/L vs 7.46 ± 7.84×109/L, p <0.001), percentage of monocytes (7.36 ± 1.36% vs 6.6 ± 1.2%, p =0.017), C-reactive protein (CRP) (2.1 mg/dL vs 1.12 mg/dL, p =0.015) and procalcitonin (PCT) (36.59% vs 3.23%, p <0.001) were significantly higher in AE-IPF patients than in stable IPF patients. Instead, the mean concentration of serum calcium and 1,25(OH)2D3 at baseline were higher in IPF patients with stable disease than in those with acute exacerbation (2.17 ± 0.13 nmol/L vs 2.09 ± 0.13 nmol/L, p =0.023 and 16.62 pg/mL vs 11.58 pg/mL, p <0.001, respectively). In multivariate analysis, a higher proportion of patients with lower serum 1,25(OH)2D3 levels experienced AE-IPF (OR 0.884, 95% CI 0.791-0.987, p =0.029), and rising serum PCT level (PCT > 0.05 ng/mL) was associated with an increased risk of mortality (HR 3.664, 95% CI 1.010-12.900, p =0.043). Decreased serum 1,25(OH)2D3 is associated with an increased risk of acute exacerbation for patients with IPF. A high serum PCT level is predictive of worse prognosis in IPF patients. 1,25(OH)2D3 may be a potential biomarker for AE-IPF, while PCT could be a prognostic biomarker for IPF.

A S tudy of the Effectiveness of Lidocaine to Treat S evere P ulmonary Vascular Constriction induced by Protamine

Abstract Background: Protamine neutralises heparin after separation from cardiopulmonary bypass. This study aimed to evaluate the effects of lidocaine on protamine induced pulmonary vascular constriction in paediatric cardiothoracic surgery. Methods: This was a single-centre, prospective, double-blind and randomised study conducted among eighty pediatric patients with acyanotic congenital cardiac disease, scheduled for elective on-pump cardiac surgery under general anaesthesia. In the study, the participants were divided into four groups: Group NPHL- nonpulmonary hypertension with lidocaine preconditioning, group NPHS- nonpulmonary hypertension with normal saline (as placebo), group PHL- pulmonary hypertension with lidocaine preconditioning, and group PHS- pulmonary hypertension with normal saline (as placebo). Results: Pulmonary vasoconstriction occurred in 11.25% of cases after protamine administration. Both the NPHS and PHS groups exhibited an increase in mean airway pressure (Paw), Respiratory index (RI), alveolar-arterial oxygen difference (A-aDO2), pulmonary artery pressure (PAP) and decreased dynamic pulmonary compliance (Cydn) and oxygen index (OI) after protamine administration. However, these changes were not observed in the NPHL and PHL groups with lidocaine preconditioning. Plasma levels of TXB2 in the NPHS and PHS groups were higher than the NPHL and PHL groups, but 6-keto-PGF1 alpha levels were lower in the NPHS and PHS groups than in the NPHL and PHL groups. Conclusion: In congenital heart disease, repair without cardiopulmonary bypass is not possible in most cases. Prior to reversing heparin with protamine, preconditioning lidocaine reverses protamine-induced pulmonary vasoconstriction and improves lung function.

Can Noninvasive Oxygen Saturation Index Match Invasive Oxygenation Index to Monitor Respiratory Disease in Critically Ill Children?—A Prospective Study

AbstractRespiratory illnesses are common indications for mechanical ventilation in children. The adequacy of ventilatory support for oxygenation is measured using arterial blood gas analysis and calculation of oxygenation index (OI). Due to invasive nature of arterial blood sampling needed to calculate OI, several researchers have replaced blood gas-derived partial pressure of oxygen values with oxygen saturation (SpO2) obtained from pulse oximetry. This noninvasive index called oxygen saturation index (OSI) is found to be useful in neonates. Studies in pediatric population is lacking. In this prospective study on mechanically ventilated children, both OI and OSI were determined and compared against alveolar–arterial oxygen difference (AaDO2). A total of 29 children were studied. Both OSI and OI had good correlation of 0.787 and 0.792 with AaDO2, respectively. OSI of 7.3 and 9.4 had good sensitivity and specificity for AaDO2 cutoffs of 344 and 498, which represents moderate and severe respiratory illness, respectively. The correlation coefficients of both OSI and OI are similar against AaDO2. OSI can be used instead of OI for constant monitoring of children on mechanical ventilation. Arterial blood gas analysis and calculation of OI can be reserved for situations where SpO2 measurement is unreliable.

Quantitative CT analysis of interstitial pneumonia in anti-melanoma differentiation-associated gene 5 antibody-positive dermatomyositis: a single center, retrospective study.

This study aimed to assess the utility of quantitative high-resolution computed tomography (HRCT) for determining the clinical course of anti-melanoma differentiation-associated gene 5 antibody-positive dermatomyositis-associated interstitial lung disease (MDA5+ ILD). This study retrospectively analyzed the data of 34 patients with MDA5+ ILD to determine the association between the clinical findings and extent of ILD via quantitative CT analysis at baseline and short-term follow-up. Quantified HRCT scores were evaluated as the lung severity score (LSS), percentage of opacity, and percentage of high opacity. Thirty-four patients underwent follow-up CT scans 35 (range: 14-78) days after diagnosis. Patients who died of rapidly progressive ILD had higher LSS (p < 0.01), percentage of opacity (p < 0.01), percentage of high opacity (p = 0.01), total ground-glass opacity score (p = 0.01), serum C-reactive protein (CRP) (p = 0.03), and alveolar-arterial oxygen difference (Aa-DO2) (p = 0.01) at follow-up than those who survived. Quantified HRCT scores correlated with serum CRP and Aa-DO2 levels at follow-up. LSS at follow-up (AUC = 0.844, p < 0.01) was the best predictor of death in MDA5+ ILD patients. Patients with an LSS of > 6.5 at follow-up had higher mortality than those with an LSS of ≤ 6.5, especially when receiving triple therapy. In multivariate analysis, an LSS of > 6.5 at follow-up was significantly associated with a poor outcome. Quantitative CT analysis of MDA5+ ILD is useful for the objective assessment of respiratory status and disease activity. Short-term HRCT evaluation, particularly LSS, is most important in predicting its clinical course during triple therapy. Key Points • Quantitative CT analysis plays an important role in evaluating the clinical course of anti-melanoma differentiation-associated gene 5 antibody-positive dermatomyositis-associated interstitial lung disease (MDA5+ ILD). • Quantified HRCT scores, particularly lung severity score, at short-term intervals from diagnosis can help to predict prognosis after triple therapy in MDA5+ ILD.

Case Studies in Physiology: Untangling the cause of hypoxemia in a patient with obesity with acute leukemia.

Diagnosing the cause of hypoxemia and dyspnea can be complicated in complex patients with multiple comorbidities. This "Case Study in Physiology" describes an man with obesity admitted to the hospital for relapse of acute lymphoblastic leukemia, who experienced progressive hypoxemia, shortness of breath, and dyspnea on exertion during his hospitalization. After initial empirical treatment with diuresis and antibiotics failed to improve his symptoms and because an arterial blood gas measurement was not readily available, we applied a novel, recently described physiological method to estimate the arterial partial pressure of oxygen from the peripheral saturation measurement and calculate the alveolar-arterial oxygen difference to discern the source of his hypoxemia and dyspnea. Using basic physiological principles, we describe how hypoventilation, anemia, and the use of a β blocker and furosemide, collaborated to create a "perfect storm" in this patient that impaired oxygen delivery and limited utilization. This case illustrates the application of innovative physiology methodology in medicine and provides a strong rationale for continuing to integrate physiology education in medical education.NEW & NOTEWORTHY Discerning the cause of dyspnea and hypoxemia in complex patients can be difficult. We describe the "real world" application of an innovative methodology to untangle the underlying physiology in a patient with multiple comorbidities. This case further demonstrates the importance of applying physiology to interrogate the underlying cause of a patient's symptoms when treatment based on probability fails.

Case Studies in Physiology: Untangling the cause of hypoxemia in an obese patient with acute leukemia

Diagnosing the cause of hypoxemia and dyspnea can be complicated in complex patients with multiple co-morbidities. This Case Study in Physiology describes an obese man admitted to the hospital for relapse of acute lymphoblastic leukemia, who experienced progressive hypoxemia, shortness of breath, and dyspnea on exertion during his hospitalization. After initial empirical treatment with diuresis and antibiotics failed to improve his symptoms, we applied a novel, recently described physiological method to estimate the arterial partial pressure of oxygen from the peripheral saturation measurement, and calculate the alveolar-arterial oxygen difference to discern the source of his hypoxemia and dyspnea. Using basic physiological principles, we describe how hypoventilation, anemia, and the use of a beta-blocker and furosemide, collaborated to create a “perfect storm” in this patient that impaired oxygen delivery and limited utilization. This case illustrates the application of innovative physiology methodology in medicine and provides strong rationale for continuing to integrate physiology education in medical education.

Cardiopulmonary Exercise Testing in Combined Pulmonary Fibrosis and Emphysema

Background: Combined pulmonary fibrosis and emphysema (CPFE) is a distinct entity among fibrosing lung diseases with a high risk for lung cancer and pulmonary hypertension (PH). Notably, concomitant PH was identified as a negative prognostic indicator that could help with early diagnosis to provide important information regarding prognosis. Objectives: The current study aimed to determine whether cardiopulmonary exercise testing (CPET) can be helpful in differentiating patients having CPFE with and without PH. Methods: Patients diagnosed with CPFE in 2 German cities (Hemer and Greifswald) over a period of 10 years were included herein. CPET parameters, such as peak oxygen uptake (peak VO₂), functional dead space ventilation (V_Df/V_T), alveolar-arterial oxygen difference (AaDO₂), arterial-end-tidal CO₂ difference [P(a-ET)CO₂] at peak exercise, and the minute ventilation-carbon dioxide production relationship (VE/VCO₂ slope), were compared between patients with and without PH. Results: A total of 41 patients with CPET (22 with PH, 19 without PH) were analyzed. Right heart catheterization was performed in 15 of 41 patients without clinically relevant complications. Significant differences in peak VO₂ (861 ± 190 vs. 1,397 ± 439 mL), VO₂/kg body weight/min (10.8 ± 2.6 vs. 17.4 ± 5.2 mL), peak AaDO₂ (72.3 ± 7.3 vs. 46.3 ± 14.2 mm Hg), VE/VCO₂ slope (70.1 ± 31.5 vs. 39.6 ± 9.6), and peak P(a-ET)tCO₂ (13.9 ± 3.5 vs. 8.1 ± 3.6 mm Hg) were observed between patients with and without PH (p < 0.001). Patients with PH had significantly higher V_Df/V_T at rest, V_T1, and at peak exercise (65.6 ± 16.8% vs. 47.2 ± 11.6%; p < 0.001) than those without PH. A cutoff value of 44 for VE/VCO₂ slope had a sensitivity and specificity of 94.7 and 72.7%, while a cutoff value of 11 mm Hg for P(a-ET)CO₂ in combination with peak AaDO₂ >60 mm Hg had a specificity and sensitivity of 95.5 and 84.2%, respectively. Combining peak AaDO₂ >60 mm Hg with peak VO₂/body weight/min <16.5 mL/kg/min provided a sensitivity and specificity of 100 and 95.5%, respectively. Conclusion: This study provided initial data on CPET among patients having CPFE with and without PH. CPET can help noninvasively detect PH and identify patients at risk. AaDO₂ at peak exercise, VE/VCO₂ slope, peak P(a-ET)CO₂, and peak VO₂ were parameters that had high sensitivity and, when combined, high specificity.

Hemodynamic effects of high frequency oscillatory ventilation with volume guarantee in a piglet model of respiratory distress syndrome.

Respiratory failure is a common condition faced by critically ill neonates with respiratory distress syndrome (RDS). High frequency oscillatory ventilation (HFOV) is often used for neonates with refractory respiratory failure related to RDS. Volume guarantee (VG) mode has been added to some HFOV ventilators for providing consistent tidal volume. We sought to examine the impact of adding the VG mode during HFOV on systemic and cerebral hemodynamics, which has not been studied to date. A neonatal piglet model of moderate to severe RDS was induced by saline lavage. Piglets (full term, age 1-3 days, weight 1.5-2.4 kg) were randomized to have RDS induced and receive either HFOV or HFOV+VG (n = 8/group) or sham-operation (n = 6) without RDS. Cardiac function measured by a Millar® catheter placed in the left ventricle as well as systemic and carotid hemodynamic and oxygen tissue saturation parameters were collected over 240 min of ventilation. Mean airway pressure, alveolar-arterial oxygen difference and left ventricular cardiac index of piglets on HFOV vs. HFOV+VG were not significantly different during the experimental period. Right common carotid artery flow index by in-situ ultrasonic flow measurement and cerebral tissue oxygen saturation (near-infrared spectroscopy) significantly decreased in HFOV+VG at 240 min compared to HFOV (14 vs. 31 ml/kg/min, and 30% vs. 43%, respectively; p<0.05). There were no significant differences in lung, brain and heart tissue markers of oxidative stress, ischemia and inflammation. HFOV+VG compared to HFOV was associated with similar left ventricular function, however HFOV+VG had a negative effect on cerebral blood flow and oxygenation.

Alveolar to arterial gas exchange during constant-load exercise in healthy active men and women

ABSTRACT Inadequate hyperventilation and inefficient alveolar to arterial gas exchange are gas exchange challenges that can limit capacity and cause exercise-induced arterial hypoxaemia (EIAH). This work evaluated if the prevalence of gas exchange inefficiencies, defined as AaDO2>25 mmHg, PaCO2>38 mmHg, and/or ΔPaO2>-10 mmHg at any point during constant-load exercise in healthy, active, but not highly trained, individuals suggested an innate sex difference that would make females more susceptible to EIAH. Sixty-four healthy, active males and females completed 18-min of cycling exercise (moderate and vigorous intensity, 9 min/stage). Arterial blood gases were measured at rest and every 3-min during exercise, while constantly assessing gas exchange. Both sexes demonstrated similar levels of AaDO2 widening until the final 3 min of vigorous exercise, where females demonstrated a trend for greater widening than males (16.3±6.2 mmHg vs. 19.1±6.0 mmHg, p=0.07). Males demonstrated a blunted ventilatory response to moderate exercise with higher PaCO2 (38.5±2.6 vs. 36.5±2.4, p=0.002) and a lower ventilation when corrected for workload (0.42±0.1 vs. 0.48±0.1, p=0.002). No significant arterial hypoxaemia occurred, but in 6 M and 5 F SaO2 dropped by ≥2%. There was no difference in prevalence of pulmonary gas exchange inefficiencies between sexes, but the type of inefficiency was influenced by sex. Abbreviations: AaDO2: alveolar-arterial oxygen difference; BP: blood pressure; EIAH: exercise-induced arterial hypoxaemia; F: females; HR: heart rate; M: males; Q: cardiac output; PaCO2: arterial partial pressure of carbon dioxide; PaO2: arterial partial pressure of oxygen; ΔPaO2: change in arterial partial pressure of oxygen; PAO2: alveolar partial pressure of oxygen; RPE: rating of perceived exertion; SaO2: arterial oxygen saturation; VE: ventilation; VE/VCO2: ventilatory equivalent for carbon dioxide; VO2PEAK: peak oxygen consumption; WMAX: workload maximum

CXCL9, CXCL10, and CXCL11; biomarkers of pulmonary inflammation associated with autoimmunity in patients with collagen vascular diseases-associated interstitial lung disease and interstitial pneumonia with autoimmune features.

Interstitial lung disease (ILD) is a heterogeneous group of diseases characterized by varying degrees of lung inflammation and/or fibrosis. We investigated biomarkers to infer whether patients with collagen vascular diseases associated ILD (CVD-ILD) and interstitial pneumonia with autoimmune features (IPAF) benefit from immunosuppressive therapy. We retrospectively investigated patients with CVD-ILD, IPAF, and idiopathic pulmonary fibrosis (IPF) between June 2013 and May 2017 at our department. First, we assessed differences in serum and bronchoalveolar lavage fluid (BALF) levels of cytokines between groups. Second, we assessed the associations of patient's clinical variables with serum and BALF levels of those cytokines that were different between groups. Finally, we assessed the associations of diagnosis and response to immunosuppressive therapy with serum levels of those cytokines that were different between groups. We included 102 patients (51 with IPF, 35 with IPAF, and 16 with CVD-ILD). Serum and BALF levels of CXCL9, CXCL10, and CXCL11 were significantly elevated in patients with IPAF or CVD-ILD compared with those in patients with IPF. BALF levels of CXCL9 and CXCL10 were correlated with the percentages of lymphocytes and macrophages in BALF. Serum levels of CXCL9 and CXCL10 were correlated with BALF levels. Serum levels of CXCL9, CXCL10, and CXCL11 were correlated C-reactive protein, percent predicted forced vital capacity, alveolar-arterial oxygen difference, and the percentages of lymphocytes and macrophages in BALF. Serum levels of CXCL9, CXCL10, and CXCL11 showed moderate accuracy to distinguish patients with CVD-ILD from those with IPAF and IPF. Pre-treatment serum levels of CXCL9 and CXCL11 showed strong positive correlations with the annual forced vital capacity changes in patients with IPAF and CVD-ILD treated with immunosuppressive drugs. Serum CXCL9, CXCL10, and CXCL11 are potential biomarkers for autoimmune inflammation and predictors of the immunosuppressive therapy responses in ILD with background autoimmunity.

Inhalation challenge test using pigeon eggs for chronic hypersensitivity pneumonitis.

Chronic hypersensitivity pneumonitis (CHP) remains a diagnostic challenge. The process of collecting and extracting serum and droppings from causative animals for the inhalation challenge test is complicated and the risk of inducing disease progression exists. To investigate the utility and safety of an inhalation challenge test using pigeon eggs. Pigeon eggs were pasteurized and mixed with a saline solution to produce an inhalation fluid. An inhalation challenge test was conducted on 19 patients with bird-related CHP and 17 patients with interstitial lung disease other than bird-related CHP. To identify antigens in pigeon eggs, the antigen-antibody responses of the pigeon eggs and serum from patients were evaluated using Western blotting. The mean changes in C-reactive protein, alveolar-arterial oxygen difference, erythrocyte sedimentation rate, and lactate dehydrogenase significantly increased by 0.32mg/dL (P=.014), 7.8Torr (P=.002), 1.4mm/h (P=.012), and 5.4 U/mL (P=.0019), respectively, in bird-related CHP group compared to the control 24hours after the inhalation challenge test. Furthermore, within 24hours of the inhalation test, the mean forced vital capacity decreased by 2.3% in the bird-related CHP group compared with a decline of 0.05% in the control group (P=.035). Serum collected from seven bird-related CHP patients who underwent the inhalation challenge test and reacted to antigens with molecular weights of 37-75 KDa, and these molecular weights were consistent with egg albumin and globulin. Since a mild response was observed after the inhalation challenge test using pigeon eggs, this test was an obvious candidate for diagnosing bird-related CHP.

New Technology for the Use of Inhaled Nitric Oxide to Protect the Heart and Lungs during Operations with Cardiopulmonary Bypass.

The aim of the study was to evaluate the effectiveness of a new technology for the use of inhaled nitric oxide (NO) for the heart and lung protection during operations with cardiopulmonary bypass (СРВ).Materials and Methods.The study included 90 patients who underwent heart valve surgery and combined procedures under CPB and pharmacological cardioplegia. Three groups were created: group 1 (control, n=30); group 2 (n=30) — NO inhalation (20 ppm) was conducted traditionally, that is, before and after CPB; group 3 (n=30) — NO inhalation was performed using a new technology — during the entire operation, with pulmonary artery perfusion and lung ventilation performed during CPB. Troponin I (cTn I) level, changes in the pulmonary function parameters, and clinical indicators were studied.Results.Statistically significant lower levels of postoperative cTn I were registered in the patients of groups 2 and 3, at the same time, the levels were significantly lower in group 3 compared to group 2. The patients in group 1 (standardized anesthesia protocol) demonstrated an increase in the alveolar-arterial oxygen difference, an increase in intrapulmonary shunting, a decrease in blood oxygenation, and static lung compliance after СРВ. In both cases, NO inhalation retained the values of lung compliance and pulmonary oxygenating function after CPB, and in the patients of group 3, it also significantly reduced intrapulmonary shunting and alveolar-arterial difference after CPB. NO inhalation allowed a statistically significant decrease in the incidence of pulmonary dysfunction, acute respiratory failure, as well as the time of respiratory support in the ICU.Conclusion.The developed technology for the use of inhaled NO in surgery with CPB provides a clinically marked protective effect on the heart and lungs. The effectiveness of the protective action of NO depends on the duration of its administration and is most pronounced when used during the entire operation, including CPB time.

Predictive effects of IgA and IgG combination to assess pulmonary exudation progression in COVID-19 patients.

Our study intended to longitudinally explore the prediction effect of immunoglobulin A (IgA) on pulmonary exudation progression in COVID‐19 patients. The serum IgA was tested with chemiluminescence method. Autoregressive moving average model was used to extrapolate the IgA levels before hospital admission. The positive rate of IgA and IgG in our cohort was 97% and 79.0%, respectively. In this study, the IgA levels peaks within 10‐15 days after admission, while the IgG levels peaks at admission. We found that the time difference between their peaks was about 10 days. Viral RNA detection results showed that the positive rate in sputum and feces were the highest. Blood gas analysis showed that deterioration of hypoxia with the enlargement of pulmonary exudation area. And alveolar‐arterial oxygen difference and oxygenation index were correlated with IgA and IgG. The results of biopsy showed that the epithelium of lung was exfoliated and the mucosa was edematous. In severe COVID‐19 patients, the combination of IgA and IgG can predict the progress of pulmonary lesions and is closely related to hypoxemia and both also play an important defense role in invasion and destruction of bronchial and alveolar epithelium by SARS‐CoV‐2.

Lung protective ventilation in infants undergoing cardiopulmonary bypass surgery for congenital heart disease: A prospective randomized controlled trial.

Lung protective ventilation (LPV) has been applied to surgical adults with normal pulmonary function for optimizing mechanical ventilation and reducing postoperative pulmonary complications. Few studies have reported the use of LPV in infants undergoing cardiac surgery with cardiopulmonary bypass (CPB). To explore safety and effectiveness of LPV in infants undergoing CPB surgery for congenital heart disease (CHD). Included in this study were 77 infants who underwent CPB surgery for CHD from November 2017 to September 2018. They were randomized into the LPV group and conventional ventilation (CV) group. In the LPV group, small-tidal-volume (6-8ml/kg) ventilation, lung recruitment by PEEP increment to the maximum level of 15cm H2 O after CPB, and individualized optimal PEEP titration were applied. In the CV group, traditional tidal volume (10-12ml/kg with zero PEEP) was applied. The primary outcome was the ratio of arterial partial pressure of oxygen to inspiratory oxygen fraction (PaO2 /FiO2 ). The secondary outcomes were respiratory dynamic parameters, hypoxemia, prognostic indexes, and postoperative pulmonary complications. PaO2 /FiO2 in the LPV group (416.86, 95%CI: 381.60-452.12) was significantly higher than that in the CV group (263.37, 95%CI: 227.65-299.09) after intervention (P<.001). There was a significant difference in the trend of change in dynamic compliance, alveolar-arterial oxygen difference, arterial-end-expired carbon dioxide difference, driving pressure, and respiratory index between the two groups at different time points from weaning from CPB to 2hours after operation. There was no significant difference in PaO2 /FiO2 , alveolar-arterial oxygen difference, respiratory index, and dynamic compliance 2hours postoperative and in the incidence of postoperative pulmonary complications, prognostic indexes between the two groups. LPV could be used safely in infants undergoing CPB in that it can improve oxygenation, alveolar aeration, and dynamic compliance, and reduce driving pressure, pulmonary shunting, and dead space. Its effect on oxygenation, pulmonary gas exchange, and pulmonary compliance was relatively short, and had less impact on postoperative pulmonary complications and prognosis.