Moderate Acute Respiratory Distress Syndrome Research Articles

Analysis of compliance with lung protective mechanical ventilation strategy in patients with acute respiratory distress syndrome

Objective: To assess the compliance with a lung protective ventilation strategy and to evaluate the relationship with prognosis in patients with acute respiratory distress syndrome (ARDS). Methods: In the prospective multicenter cohort study (CHARDS), patients with ARDS undergoing invasive mechanical ventilation were enrolled to collect essential information, mechanical ventilation data, and prognostic data. Compliance was operationally defined as tidal volume ≤7 ml/kg predicted body weight (PBW) or plateau pressure ≤30 cmH2O or driving pressure≤15 cmH2O. Tidal volume data collected 7 days prior to ventilation after ARDS diagnosis were categorized into four groups: standard group (Group A, 100% compliance), non-standard group (Group B, 50%-99% compliance, Group C,1%-49% compliance,and Group D,totally non-compliant). Plateau pressure and drive pressure measurements were recorded on the first day. Stepwise regression, specifically Logistics regression, was used to identify the factors influencing ICU survival. Results: A total of 449 ARDS patients with invasive mechanical ventilation were included; the proportion of mild, moderate, and severe patients was 71 (15.8%), 198 (44.1%) and 180 (40.1%), respectively. During the first 7 days, a total of 2880 tidal volume measurements were recorded with an average tidal volume of (6.89±1.93) ml/kg PBW. Of these measurements, 53.2% were found to be≤7 ml/kg PBW. The rates of compliance with lung protective mechanical ventilation were 29.8% (134/449), 24.5% (110/449), 23.6% (106/449), and 22% (99/449) in groups A, B, C, and D, respectively. In the standard group, the tidal volume for mild ARDS patients was 18.3%(13/71), while it was 81.7%(58/71)in the non-standard group. Similarly, in patients with moderate ARDS, the tidal volume was 25.8% (51/198) in the standard group, while it was 74.2% (147/198) in the non-standard group. Finally, in patients with severe ARDS, the tidal volume was 38.9% (70/180) in the standard group, while it was 61.1% (110/180) in the non-standard group. Notably, the compliance rate was higher in patients with moderate and severe ARDS in group A compared to patients with mild and moderate ARDS (18.3% vs. 25.8% vs. 38.9%, χ2=13.124, P=0.001). Plateau pressure was recorded in 221 patients, 95.9% (212/221) patients with plateau pressure≤30 cmH2O, and driving pressure was recorded in 207 patients, 77.8% (161/207) patients with a driving pressure ≤15 cmH2O.During the first 7 days, the mortality rate in the intensive care unit (ICU) was lower in the tidal volume standard group compared to the non-standard group (34.6% vs. 51.3%, χ2=10.464, P=0.001). In addition, the in-hospital mortality rate was lower in the standard group compared to the non-standard group (39.8% vs. 57%, χ2=11.016, P=0.001).The results of the subgroup analysis showed that the mortality rates of moderate and severe ARDS patients in the standard group were significantly lower than those in the non-standard group, both in the ICU and in the hospital (all P<0.05). However, there was no statistically significant difference in mortality among mild ARDS patients (all P>0.05). Conclusions: There was high compliance with recommended lung protective mechanical ventilation strategies in ARDS patients, with slightly lower compliance in patients with mild ARDS, and high compliance rates for plateau and drive pressures. The tidal volume full compliance group had a lower mortality than the non-compliance group, and showed a similar trend in the moderate-to-severe ARDS subgroup, but there was no significant correlation between compliance and prognosis in patients with mild ARDS subgroup.

Case Report: Scrub Typhus manifesting as Acute Respiratory Distress Syndrome (ARDS) with corresponding radiological findings

Background Scrub typhus is a life-threatening infectious disease endemic in the Asia-Pacific region. It typically presents with nonspecific symptoms such as fever, headache, and myalgia, making early diagnosis challenging. Acute Respiratory Distress Syndrome (ARDS) is a severe pulmonary condition characterized by acute-onset hypoxemia, bilateral lung infiltrates on radiology, and increased pulmonary capillary permeability. Case Presentation An 18-year-old female student in central India presented with a seven-day history of recurrent fever, chills, dry cough, and severe shortness of breath, escalating to Modified Medical Research Council dyspnea grade III-IV. After unsuccessful local clinic treatment, a chest radiograph revealed bilateral pneumonia. On admission, she displayed tachycardia, tachypnea, hypotension, and hypoxia requiring non-invasive ventilation (NIV). Computed tomography confirmed scrub typhus-associated pneumonia, and serological testing was positive for scrub typhus. She was diagnosed with moderate ARDS and began treatment. Symptomatic improvement was seen in the ICU, and she was discharged on day 10 with radiological and clinical resolution. Management and Outcomes She received intravenous doxycycline and oral azithromycin for scrub typhus and any potential concurrent lung infection. In the ICU, she required continuous NIV and supplemental oxygen, with significant symptomatic improvement, evidenced by reduced tachypnoea and oxygen requirements after 72 hours. She was weaned off NIV and monitored for an additional four days. After satisfactory oxygen saturation on room air, she was discharged on the tenth day. High-resolution CT scan demonstrated resolution of ground glass opacities and consolidation. Sequential chest radiographs exhibited gradual reduction in bilateral alveolar infiltrates over time, in parallel with clinical improvement. Laboratory findings, including reduced CRP and D-dimer values, and a normal hemogram on discharge indicated a resolution of leukopenia. Conclusion This case underscores the importance of early recognition and intervention in scrub typhus-associated ARDS and highlights the utility of timely diagnostic imaging in monitoring the progress of the disease.

Contribution of electrical impedance tomography to personalize positive end-expiratory pressure under ECCO2R

Extracorporeal Carbon Dioxide Removal (ECCO2R) is used in acute respiratory distress syndrome (ARDS) patients to facilitate lung-protective ventilatory strategies. Electrical Impedance Tomography (EIT) allows individual, non-invasive, real-time, bedside, radiation-free imaging of the lungs, providing global and regional dynamic lung analyses. To provide new insights for future ECCO2R research in ARDS, we propose a potential application of EIT to personalize End-Expiratory Pressure (PEEP) following each reduction in tidal volume (VT), as demonstrated in an illustrative case. A 72-year-old male with COVID-19 was admitted to the ICU for moderate ARDS. Monitoring with EIT was started to determine the optimal PEEP value (PEEPEIT), defined as the intersection of the collapse and overdistention curves, after each reduction in VT during ECCO2R. The identified PEEPEIT values were notably low (< 10 cmH2O). The decrease in VT associated with PEEPEIT levels resulted in improved lung compliance, reduced driving pressure and a more uniform ventilation pattern. Despite current Randomized Controlled Trials showing that ultra-protective ventilation with ECCO2R does not improve survival, the applicability of universal ultra-protective ventilation settings for all patients remains a subject of debate. Inappropriately set PEEP levels can lead to alveolar collapse or overdistension, potentially negating the benefits of VT reduction. EIT facilitates real-time monitoring of derecruitment associated with VT reduction, guiding physicians in determining the optimal PEEP value after each decrease in tidal volume. This original description of using EIT under ECCO2R to adjust PEEP at a level compromising between recruitability and overdistention could be a crucial element for future research on ECCO2R.

Predictive role of regional thigh tissue oxygen saturation monitoring during cardiopulmonary bypass in lung injury after cardiac surgery.

Acute respiratory distress syndrome (ARDS) is a serious complication following cardiac surgery mainly associated with the use of cardiopulmonary bypass (CPB), which could increase the risk of mortality and morbidity. This study investigated the association of regional oxygen saturation (rSO2) during CPB with postoperative outcomes, including respiratory function. Patients who underwent cardiac surgery with CPB from 2015 to 2019 were included. Near-infrared spectroscopy was used to monitor rSO2 at the forehead, abdomen, and thighs throughout the surgery. Postoperative markers associated with CPB were assessed for correlations with PaO2/FiO2 (P/F) ratios at intensive care unit (ICU) admission. Postoperative lung injury (LI) was defined as moderate or severe ARDS based on the Berlin criteria, and its incidence was 29.9% (20/67). On multiple regression analysis, the following were associated with P/F ratios at ICU admission: vasoactive-inotropic scores at CPB induction (P = 0.03), thigh rSO2 values during CPB (P = 0.04), and body surface area (P < 0.001). A thigh rSO2 of 71% during CPB was significantly predictive of postoperative LI with an area under the curve of 0.71 (P = 0.03), sensitivity of 0.70, and specificity of 0.68. Patients with postoperative LI had longer ventilation time and ICU stays. Thigh rSO2 values during CPB were a potential predictor of postoperative pulmonary outcomes.

Comparison of SpO2- with PaO2-Based Indices of Oxygenation in Children with Respiratory Failure

AbstractGiven the widespread availability of pulse oximetry and its potential to replace partial pressure of arterial oxygen (PaO2)-based indices of oxygenation, we aimed to study the correlation between pulse oximetry-based oxygen saturation (SpO2)- and PaO2-based indices of oxygenation namely, SpO2/FiO2 (SF) ratio with PaO2/FiO2 (PF) ratio and oxygen saturation index (OSI) with oxygenation index (OI) under varying physiological conditions, along with accuracy measures for SpO2-based indices. Inclusion criteria included children (1 month to 18 years) admitted to pediatric intensive care unit needing invasive ventilation for hypoxemic respiratory failure with SpO2 ≥ 80% and having an indwelling arterial catheter. A total of 1,237 sets of simultaneous PaO2, SpO2 readings, and ventilator parameters were recorded. There was a moderate correlation between SF and PF ratios (r s = 0.68, p &lt; 0.001) and strong correlation between OSI and OI (r s = 0.89, p &lt; 0.001). We obtained SF ratios of 271, 235, and 200 corresponding to PF ratios of 300, 200, and 100, respectively. SF ratio showed a good discrimination ability to identify moderate (area under the receiver operating characteristic curve [AUROC] = 0.901) and severe acute respiratory distress syndrome (ARDS; AUROC = 0.889) and fair discrimination ability for mild ARDS (AUROC = 0.770). OSI of 4.1, 6.4, and 11.1 corresponded to OI of 4, 8, and 16, respectively. OSI demonstrated an excellent discrimination ability for diagnosing mild (AUROC = 0.928), moderate (AUROC = 0.961), and severe ARDS (AUROC = 0.965). The correlation between SF/PF ratio and OSI/OI was the strongest in the lowest SpO2 range studied. SpO2-based indices of oxygenation could replace PaO2-based indices with reasonable accuracy for patients with SpO2 values ≥ 80%.

Attributable mortality of ARDS among critically ill patients with sepsis: a multicenter, retrospective cohort study

BackgroundBoth sepsis and acute respiratory distress syndrome (ARDS) are common severe diseases in the intensive care unit (ICU). There is no large-scale multicenter study to clarify the attributable mortality of ARDS among septic patients. This study aimed to evaluate the excess mortality of ARDS in critically ill patients with sepsis.MethodsThe data were obtained from a multicenter, prospective cohort study in 18 Chinese ICUs between January 2014 and August 2015. The study population was septic patients after ICU admission. The patients were categorized into two groups: those who developed ARDS (ARDS group) within seven days following a sepsis diagnosis and those who did not develop ARDS (non-ARDS group). Applying propensity score matching (PSM), patients were matched 1:1 as ARDS and non-ARDS groups. Mortality attributed to ARDS was calculated. Subsequently, we conducted a survival analysis to estimate the impact of ARDS on mortality. The primary endpoint was 30-day mortality after sepsis diagnosis.Results2323 septic patients were eligible, 67.8% developed ARDS. After PSM, 737 patients with ARDS were matched 1:1 with 737 non-ARDS patients. ARDS’s overall 30-day attributable mortality was 11.9% (95% CI 7.5–16.3%, p < 0.001). Subgroup analysis showed that the 30-day attributable mortality of mild, moderate, and severe ARDS was 10.5% (95% CI 4.0-16.8%, p < 0.001), 11.6% (95% CI 4.7–18.4%, p < 0.001) and 18.1% (95% CI 4.5–30.9%, p = 0.006), respectively. ARDS was an independent risk factor for 30-day mortality, with adjusted hazard ratios of 1.30 (95% CI 1.03–1.64, p = 0.027), 1.49 (95% CI 1.20–1.85, p < 0.001), and 1.95 (95% CI 1.51–2.52, p < 0.001) for mild, moderate, and severe ARDS, respectively.ConclusionsThe overall 30-day attributable mortality of ARDS among critically ill patients with sepsis was 11.9%. Compared with mild and moderate ARDS, severe ARDS contributed more to death. ARDS was significantly associated with an increase in the 30-day mortality.

Clinical research progress in non-invasive positive pressure ventilation in 2023

Non-invasive positive pressure ventilation (NPPV) is a widely used method of providing respiratory support in a variety of clinical settings, including emergency departments, general wards, and intensive care units. The relevant research articles on NPPV published between 1st October 2022 and 30th September 2023 were retrieved from Medline and reviewed. In the management of acute respiratory failure (ARF) associated with COVID-19, studies have highlighted the significant influence of regional economic status on the choice of respiratory support strategies. It has been observed that NPPV is more suitable for patients with mild to moderate acute respiratory distress syndrome (ARDS) than for those with severe ARDS, as the latter group has an increased risk of delayed intubation. In addition, patients with severe dyspnea tended to benefit more from NPPV compared with high flow nasal cannula (HFNC) and conventional oxygen therapy, with a reduced risk of self-induced lung injury. For non-COVID-19-related ARF, research shows no significant differences in mortality and intubation rates between HFNC and NPPV in patients with hypercapnic ARF. The updated HACOR score and ROX score have been validated to have a high predictive value for clinical outcomes in patients receiving NPPV for hypoxemic ARF. With regard to weaning from invasive mechanical ventilation, immediate application of NPPV after extubation showed a lower mortality rate compared to continued invasive weaning. Moreover, NPPV with active humidification significantly decreased the reintubation rate within 7 days after extubation compared with HFNC. The choice between using NPPV and HFNC should be based on the specific etiology of the patient's condition. The potential effect of noninvasive high-frequency oscillatory ventilation on CO2 clearance was also investigated.

The Triglycerides and Glucose Index Is an Independent Risk Factor for Acute Respiratory Distress Syndrome in Patients with COVID-19.

Introduction: Although it has been observed that the triglycerides and glucose (TyG) index, a biomarker of insulin resistance, is associated with severity and morbidity by COVID-19, evidence is still scarce. Therefore, the objective of this study was to determine whether the TyG index is associated with both the degree of severity and mortality by acute respiratory distress syndrome (ARDS) in patients with COVID-19. Methods: Men and women aged 20 years or more with diagnosis of COVID-19 were included in a case-control study. Exclusion criteria were pregnancy, cancer, autoimmune diseases, autoimmune treatment, and incomplete data. Patients with severe COVID-19 ARDS were allocated into the case group, and those with mild or moderate COVID-19 ARDS in the control group. COVID-19 was defined by a positive reverse transcriptase-polymerase chain reaction test for SARS-CoV-2, and ARDS was defined according to the Berlin criteria. Results: A total of 206 patients were included and allocated into the case (n = 103) and control (n = 103) groups. The logistic regression analysis adjusted by age, sex, and body mass index showed that the TyG index is significantly associated with moderate [odds ratio (OR) = 6.0; 95% confidence interval (CI): 1.1-30.6] and severe (OR = 9.5; 95% CI: 2.4-37.5) COVID-19 ARDS, and death (OR = 10.1; 95% CI: 2.2-46.5). Conclusion: The results of our study show a significant and independent association of the TyG index with ARDS and mortality in patients with COVID-19.

Phenotypes of esophageal pressure response to the change of positive end-expiratory pressure in patients with moderate acute respiratory distress syndrome.

Esophageal pressure (Pes) has been used as a surrogate of pleural pressure (Ppl) to titrate positive end-expiratory pressure (PEEP) in acute respiratory distress syndrome (ARDS) patients. The relationship between Pes and PEEP remains undetermined. A gastric tube with a balloon catheter was inserted to monitor Pes in moderate to severe ARDS patients who underwent invasive mechanical ventilation. To assess the end-expiratory Pes response (ΔPes) to PEEP changes (ΔPEEP), the PEEP level was decreased and increased subsequently (with an average change of 3 cmH2O). The patients underwent the following two series of PEEP adjustment: (I) from PEEP-3 cmH2O to PEEPbaseline; and (II) from PEEPbaseline to PEEP+3 cmH2O. The patients were classified as "PEEP-dependent type" if they had ΔPes ≥30% ΔPEEP and were otherwise classified as "PEEP-independent type" (ΔPes <30% ΔPEEP in any series). In total, 54 series of PEEP adjustments were performed in 18 ARDS patients. Of these patients, 12 were classified as PEEP-dependent type, and six were classified as PEEP-independent type. During the PEEP adjustment, end-expiratory Pes changed significantly in the PEEP-dependent patients, who had a Pes of 10.8 (7.9, 12.3), 12.5 (10.5, 14.9), and 14.5 (13.1, 18.3) cmH2O at PEEP-3 cmH2O, PEEPbaseline, and PEEP+3 cmH2O, respectively (median and quartiles; P<0.0001), while end-expiratory transpulmonary pressure (PL) was maintained at an optimal range [-0.1 (-0.7, 0.4), 0.1 (-0.6, 0.5), and 0.3 (-0.3, 0.7) cmH2O, respectively]. In the PEEP-independent patients, the Pes remained unchanged, with a Pes of 15.4 (11.4, 17.8), 15.5 (11.6, 17.8), and 15.4 (11.7, 18.30) cmH2O at each of the three PEEP levels, respectively. Meanwhile, end-expiratory PL significantly improved [from -5.5 (-8.5, -3.4) at PEEP-3 cmH2O to -2.5 (-5.0, -1.6) at PEEPbaseline to -0.5 (-1.8, 0.3) at PEEP+3 cmH2O; P<0.01]. Two types of Pes phenotypes were identified according to the ΔPes to ΔPEEP. The underlying mechanisms and implications for clinical practice require further exploration.

Clinical Profile and Outcome of Moderate to Severe Acute Respiratory Distress Syndrome in a Paediatric Intensive Care Unit of Eastern India: A Prospective Cohort Study

Introduction: Paediatric Acute Respiratory Distress Syndrome (PARDS) remains a major cause of mortality and morbidity in Paediatric Intensive Care Units (PICU) despite various advanced management strategies. The management and outcome of PARDS depend on the severity of the disease. Aim: To study the clinical profile in terms of aetiology and outcome of paediatric patients with moderate to severe Acute Respiratory Distress Syndrome (ARDS) in the PICU. Materials and Methods: A prospective cohort study was conducted at the PICU in Dr. BC Roy Postgraduate Institute of Paediatric Sciences, Kolkata, West Bengal, India, from July 2018 to June 2019. A total of 120 children aged between two months and 12 years who developed moderate to severe ARDS according to Paediatric Acute Lung Injury Consensus Conference (PALICC) criteria were included. Demographic details, different risk factors, morbidity patterns, and outcomes were recorded. Patients were categorised into three groups based on Positive End Expiratory Pressure (PEEP): 5-8 cm of H2 O, 9-12 cm of H2 O, and &gt;12 cm of H2 O. Based on Peak Inspiratory Pressure (PIP), patients were divided into two groups: &lt;30 cm of H2 O and 30-35 cm of H2 O. Data were statistically analysed using the Chisquare test, Fisher’s test, and t-tests where applicable. Results: Out of a total of 120 children with moderate to severe ARDS, there were 75 males and 45 females. Direct lung injury accounted for 79 cases (65.5%), while indirect lung injury occurred in 41 cases (34.5%). Pneumonia and sepsis were the most common causes of direct and indirect lung injury, respectively. Among 75 cases of pneumonia, 40 deaths were reported (53.3%), and out of 37 cases of sepsis, 31 resulted in death (83%). On the day of admission, 38.3% of cases were classified as moderate ARDS and 61.7% as severe ARDS. The mortality rate for severe ARDS was 77%, compared to 43.5% for moderate ARDS. The mortality rate was 100% in the PEEP max &gt;12 cm of H2 O group and 84.4% in the PIP 30-35 cm of H2 O group. Conclusion: The majority of ARDS cases are due to direct lung injury caused by pneumonia, and the outcome is better than in cases of indirect lung injury. Mortality is nearly twice as high in severe ARDS as in moderate ARDS.

Prevalence, predictors, and outcomes of acute respiratory distress syndrome in severe stroke.

Patients with severe stroke are at high risk of developing acute respiratory distress syndrome (ARDS), but this severe complication was often under-diagnosed and rarely explored in stroke patients. We aimed to investigate the prevalence, early predictors, and outcomes of ARDS in severe stroke. This prospective study included consecutive patients admitted to neurological intensive care unit (neuro-ICU) with severe stroke, including acute ischemic stroke, intracerebral hemorrhage, and subarachnoid hemorrhage. The incidence of ARDS was examined, and baseline characteristics and severity scores on admission were investigated as potential early predictors for ARDS. The in-hospital mortality, length of neuro-ICU stay, the total cost in neuro-ICU, and neurological functions at 90days were explored. Of 140 patients included, 35 (25.0%) developed ARDS. Over 90% of ARDS cases occurred within 1week of admission. Procalcitonin (OR 1.310 95% CI 1.005-1.707, P = 0.046) and PaO2/FiO2 on admission (OR 0.986, 95% CI 0.979-0.993, P < 0.001) were independently associated with ARDS, and high brain natriuretic peptide (OR0.994, 95% CI 0.989-0.998, P = 0.003) was a red flag biomarker warning that the respiratory symptoms may be caused by cardiac failure rather than ARDS. ARDS patients had longer stays and higher expenses in neuro-ICU. Among patients with ARDS, 25 (62.5%) were moderate or severe ARDS. All the patients with moderate to severe ARDS had an unfavorable outcome at 90days. ARDS is common in patients with severe stroke, with most cases occurring in the first week of admission. Procalcitonin and PaO2/FiO2 on admission are early predictors of ARDS. ARDS worsens both short-term and long-term outcomes. The conflict in respiratory support strategies between ARDS and severe stroke needs to be further studied.

Case Report: Scrub Typhus manifesting as Acute Respiratory Distress Syndrome (ARDS) with corresponding radiological findings: A Case Report

Background Scrub typhus is a life-threatening infectious disease endemic in the Asia-Pacific region. It typically presents with nonspecific symptoms such as fever, headache, and myalgia, making early diagnosis challenging. Acute Respiratory Distress Syndrome (ARDS) is a severe pulmonary condition characterized by acute-onset hypoxemia, bilateral lung infiltrates on radiology, and increased pulmonary capillary permeability. Case Presentation An 18-year-old female student in central India presented with a seven-day history of recurrent fever, chills, dry cough, and severe shortness of breath, escalating to Modified Medical Research Council dyspnea grade III-IV. After unsuccessful local clinic treatment, a chest radiograph revealed bilateral pneumonia. On admission, she displayed tachycardia, tachypnea, hypotension, and hypoxia requiring non-invasive ventilation (NIV). Computed tomography confirmed scrub typhus-associated pneumonia, and serological testing was positive for scrub typhus. She was diagnosed with moderate ARDS and began treatment. Symptomatic improvement was seen in the ICU, and she was discharged on day 10 with radiological and clinical resolution. Management and Outcomes She received intravenous doxycycline and oral azithromycin for scrub typhus and any potential concurrent lung infection. In the ICU, she required continuous NIV and supplemental oxygen, with significant symptomatic improvement, evidenced by reduced tachypnoea and oxygen requirements after 72 hours. She was weaned off NIV and monitored for an additional four days. After satisfactory oxygen saturation on room air, she was discharged on the tenth day. High-resolution CT scan demonstrated resolution of ground glass opacities and consolidation. Sequential chest radiographs exhibited gradual reduction in bilateral alveolar infiltrates over time, in parallel with clinical improvement. Laboratory findings, including reduced CRP and D-dimer values, and a normal hemogram on discharge indicated a resolution of leukopenia. Conclusion This case underscores the importance of early recognition and intervention in scrub typhus-associated ARDS and highlights the utility of timely diagnostic imaging in monitoring the progress of the disease.

An Initial Investigation of Diaphragm Neurostimulation in Patients with Acute Respiratory Distress Syndrome.

Lung protective ventilation aims at limiting lung stress and strain. By reducing the amount of pressure transmitted by the ventilator into the lungs, diaphragm neurostimulation offers a promising approach to minimize ventilator-induced lung injury. This study investigates the physiologic effects of diaphragm neurostimulation in acute respiratory distress syndrome (ARDS) patients. The hypothesis was that diaphragm neurostimulation would improve oxygenation, would limit the distending pressures of the lungs, and would improve cardiac output. Patients with moderate ARDS were included after 48 h of invasive mechanical ventilation and had a left subclavian catheter placed to deliver bilateral transvenous phrenic nerve stimulation. Two 60-min volume-controlled mechanical ventilation (control) sessions were interspersed by two 60-min diaphragm neurostimulation sessions delivered continually, in synchrony with the ventilator. Gas exchange, lung mechanics, chest electrical impedance tomography, and cardiac index were continuously monitored and compared across four sessions. The primary endpoint was the Pao2/fraction of inspired oxygen (Fio2) ratio at the end of each session, and the secondary endpoints were lung mechanics and hemodynamics. Thirteen patients were enrolled but the catheter could not be inserted in one, leaving 12 patients for analysis. All sessions were conducted without interruption and well tolerated. The Pao2/Fio2 ratio did not change during the four sessions. Median (interquartile range) plateau pressure was 23 (20 to 31) cm H2O and 21 (17 to 25) cm H2O, driving pressure was 14 (12 to 18) cm H2O and 11 (10 to 13) cm H2O, and end-inspiratory transpulmonary pressure was 9 (5 to 11) cm H2O and 7 (4 to 11) cm H2O during mechanical ventilation alone and during mechanical ventilation + neurostimulation session, respectively. The dorsal/ventral ventilation surface ratio was 0.70 (0.54 to 0.91) when on mechanical ventilation and 1.20 (0.76 to 1.33) during the mechanical ventilation + neurostimulation session. The cardiac index was 2.7 (2.3 to 3.5) l · min-1 · m-2 on mechanical ventilation and 3.0 (2.4 to 3.9) l · min-1 · m-2 on mechanical ventilation + neurostimulation. This proof-of-concept study showed the feasibility of short-term diaphragm neurostimulation in conjunction with mechanical ventilation in ARDS patients. Diaphragm neurostimulation was associated with positive effects on lung mechanics and on hemodynamics.

Abstract 185: Regional Oxygen Saturation and Capnography Monitoring During Resuscitation After Cardiac Arrest in a Swine Pediatric ARDS Model

Introduction: Survival and outcomes after cardiac arrest (CA) depend largely on the effectiveness of cardiopulmonary resuscitation (CPR). Traditional invasive methods of monitoring CPR can be challenging out-of-hospital and are lacking in more than 50% of in-hospital pediatric CA. Regional oxygen saturation (rSO 2 ) monitoring with Near Infrared Spectroscopy (NIRS) and volumetric capnography offers a noninvasive approach that could potentially overcome these challenges. Aim: To determine the feasibility and effectiveness of NIRS and volumetric capnography monitoring in a swine model of pediatric hypoxia induced CA. Approach: Juvenile pigs were sedated and mechanically ventilated. Mild to moderate Acute Respiratory Distress Syndrome (ARDS) was induced by continuous oleic acid infusion. Respiratory and hemodynamic variables were monitored using invasive and noninvasive (NIRS and capnography) monitoring to assess efficacy of CPR. Animals were randomized into one of the two groups: High-quality CPR (hqCPR) to achieve coronary perfusion pressure of 25-30 mmHg and low-quality CPR (lqCPR) to achieve coronary perfusion pressure of 10-15 mmHg. Trajectories over time were analyzed using regression analyses. The discriminatory ability to distinguish between groups based on trajectories were analyzed using receiver operating characteristics curve (ROC) analysis. Results: 39 animals (23±3 kg) were included in our study. In the hqCPR group, there are generally higher values for cerebral and renal rSO 2 , ETCO 2 , volume of CO 2 elimination (VCO 2 ), and carotid blood flow, compared to the lqCPR group (p&lt;0.0001). Cerebral and renal rSO 2 values increase over time, while ETCO 2 , VCO 2 , and carotid flow values decrease in the hqCPR group. Cerebral rSO2 had a ROC AUC of 0.76 (95% CI: 0.58-0.94), whereas renal rSO2 had a ROC AUC of 0.54 (95% CI: 0.22-0.87) representing nearly no discrimination ability. ETCO 2 had a ROC AUC of 0.66 (95% CI: 0.49-0.84), whereas VCO 2 had a ROC AUC of 0.62 (95% CI: 0.38-0.85). Conclusions: Higher mean cerebral rSO2 values during CPR might be used to assess quality of CPR effectiveness and provide real-time adjustments as needed. This could guide healthcare providers in optimizing CPR quality and improving outcomes for cardiac arrest patients.

Effect and mechanical mechanism of spontaneous breathing on oxygenation and lung injury in mild or moderate animal ARDS

ObjectiveThe present study aimed to determine the effect and mechanical mechanism of spontaneous breathing during mechanical ventilation on oxygenation and lung injury using Beagles dogs mild or moderate acute respiratory distress syndrome (ARDS) model.MethodsAfter inducing mild or moderate ARDS by infusion of oleic acid, Eighteen Beagles dogs were randomly split into Spontaneous breathing group (BIPAPSB, n = 6), and Complete muscle paralysis group (BIPAPPC, n = 6),Six Beagles without ventilator support comprised the control group. Both groups were ventilated for 8 h under BIPAP mode. High-pressure was titrated TV to 6 ml/kg. A multi-pair esophageal balloon electrode catheter was used to measure respiratory mechanics and electromyogram. End-expiratory lung volume (EELV), gas exchange and respiratory variables were recorded in the process of mechanical ventilation. The contents of Interleukin (IL)-6 and IL-8 in lung tissue were measure using qRT-PCR. Besides, lung injury score was calculated in the end of mechanical ventilation.ResultsBased on the comparable setting of ventilator, BIPAPSB group exhibited higher safety peak transpulmonary pressure, abdominal pressure, EELV and P/F(PaO2/FiO2) than BIPAPPC group, whereas mean transpulmonary pressure, the mRNA levels of the IL-6 and IL-8 in the lung tissues and lung injury score in BIPAPSB group were lower than those in BIPAPPC group.ConclusionIn mild to moderate ARDS animal models, during mechanical ventilation, SB may improve respiratory function and reduce ventilator-induced lung injury. The mechanism may be that spontaneous inspiration up-regulates peak transpulmonary pressure and EELV; Spontaneous expiration decreases mean transpulmonary pressure by up-regulating intra-abdominal pressure, thereby reducing stress and strain.

Prediction model for in-hospital mortality in patients at high altitudes with ARDS due to COVID-19.

The diagnosis of acute respiratory distress syndrome (ARDS) includes the ratio of pressure arterial oxygen and inspired oxygen fraction (P/F) ≤ 300, which is often adjusted in locations more than 1,000 meters above sea level (masl) due to hypobaric hypoxemia. The main objective of this study was to develop a prediction model for in-hospital mortality among patients with ARDS due to coronavirus disease 2019 (COVID-19) (C-ARDS) at 2,600 masl with easily available variables at patient admission and to compare its discrimination capacity with a second model using the P/F adjusted for this high altitude. This study was an analysis of data from patients with C-ARDS treated between March 2020 and July 2021 in a university hospital located in the city of Bogotá, Colombia, at 2,600 masl. Demographic and laboratory data were extracted from electronic records. For the prediction model, univariate analyses were performed to screen variables with p <0.25. Then, these variables were automatically selected with a backward stepwise approach with a significance level of 0.1. The interaction terms and fractional polynomials were also examined in the final model. Multiple imputation procedures and bootstraps were used to obtain the coefficients with the best external validation. In addition, total adjustment of the model and logistic regression diagnostics were performed. The same methodology was used to develop a second model with the P/F adjusted for altitude. Finally, the areas under the curve (AUCs) of the receiver operating characteristic (ROC) curves of the two models were compared. A total of 2,210 subjects were included in the final analysis. The final model included 11 variables without interaction terms or nonlinear functions. The coefficients are presented excluding influential observations. The final equation for the model fit was g(x) = age(0.04819)+weight(0.00653)+height(-0.01856)+haemoglobin(-0.0916)+platelet count(-0.003614)+ creatinine(0.0958)+lactate dehydrogenase(0.001589)+sodium(-0.02298)+potassium(0.1574)+systolic pressure(-0.00308)+if moderate ARDS(0.628)+if severe ARDS(1.379), and the probability of in-hospital death was p (x) = e g (x)/(1+ e g (x)). The AUC of the ROC curve was 0.7601 (95% confidence interval (CI) 0.74-0, 78). The second model with the adjusted P/F presented an AUC of 0.754 (95% CI 0.73-0.77). No statistically significant difference was found between the AUC curves (p value = 0.6795). This study presents a prediction model for patients with C-ARDS at 2,600 masl with easily available admission variables for early stratification of in-hospital mortality risk. Adjusting the P/F for 2,600 masl did not improve the predictive capacity of the model. We do not recommend adjusting the P/F for altitude.

The Use of High-Flow Nasal Cannula and Non-Invasive Mechanical Ventilation in the Management of COVID-19 Patients: A Prospective Study.

High-flow nasal cannula (HFNC) and ventilator-delivered non-invasive mechanical ventilation (NIV) were used to treat acute respiratory distress syndrome (ARDS) due to COVID-19 pneumonia, especially in low- and middle-income countries (LMICs), due to lack of ventilators and manpower resources despite the paucity of data regarding their efficacy. This prospective study aimed to analyse the efficacy of HFNC versus NIV in the management of COVID-19 ARDS. A total of 88 RT-PCR-confirmed COVID-19 patients with moderate ARDS were recruited. Linear regression and generalized estimating equations (GEEs) were used for trends in vital parameters over time. A total of 37 patients were on HFNC, and 51 were on NIV. Patients in the HFNC group stayed slightly but not significantly longer in the ICU as compared to their NIV counterparts (HFNC vs. NIV: 8.00 (4.0-12.0) days vs. 7.00 (2.0-12.0) days; p = 0.055). Intubation rates, complications, and mortality were similar in both groups. The switch to HFNC from NIV was 5.8%, while 37.8% required a switch to NIV from HFNC. The resolution of respiratory alkalosis was better with NIV. We conclude that in patients with COVID-19 pneumonia with moderate ARDS, the duration of treatment in the ICU, intubation rate, and mortality did not differ significantly with the use of HFNC or NIV for respiratory support.

Efficacy of Wharton Jelly Mesenchymal Stromal Cells infusions in moderate to severe SARS-Cov-2 related acute respiratory distress syndrome: a phase 2a double-blind randomized controlled trial.

The COVID-19 pandemic caused a wave of acute respiratory distress syndrome (ARDS) with a high in-hospital mortality, especially in patients requiring invasive mechanical ventilation. Wharton Jelly-derived Mesenchymal Stromal Cells (WJ-MSCs) may counteract the pulmonary damage induced by the SARS-CoV-2 infection through pro-angiogenic effects, lung epithelial cell protection, and immunomodulation. In this randomized, double-blind, placebo-controlled phase 2a trial, adult patients receiving invasive mechanical ventilation for SARS-CoV-2 induced moderate or severe ARDS were assigned to receive 1 intravenous infusion of 1 × 106 WJ-MSCs/kg or placebo within 48 h of invasive ventilation followed by 2 infusions of 0.5 × 106 WJ-MSCs/kg or placebo over 5 days. The primary endpoint was the percentage of patients with a PaO2/FiO2 > 200 on day 10. Thirty patients were included from November 2020 to May 2021, 15 in the WJ-MSC group and 15 in the placebo group. We did not find any significant difference in the PaO2/FiO2 ratio at day 10, with 18 and 15% of WJ-MSCs and placebo-treated patients reaching a ratio >200, respectively. Survival did not differ in the 2 groups with a 20% mortality rate at day 90. While we observed a higher number of ventilation-free days at 28 days in the WJ-MSC arm, this difference was not statistically significant (median of 11 (0-22) vs. 0 (0-18), p = 0.2). The infusions were well tolerated, with a low incidence of anti-HLA alloimmunization after 90 days. While treatment with WJ-MSCs appeared safe and feasible in patients with SARS-CoV2 moderate or severe ARDS in this phase 2a trial, the treatment was not associated with an increased percentage of patients with P/F > 200 at 10d, nor did 90 day mortality improve in the treated group. https://beta.clinicaltrials.gov/study/NCT04625738, identifier NCT04625738.

The Efficacy of High-Dose Pulse Therapy vs. Low-Dose Intravenous Methylprednisolone on Severe to Critical COVID-19 Clinical Outcomes: A Randomized Clinical Trial.

It remains unclear which formulation of the corticosteroid regimen has the optimum efficacies on COVID-19 pneumonia. The aim of this study was to compare the clinical outcomes of 2 different regimens in the treatment of acute respiratory distress syndrome (ARDS) caused by COVID-19: Methylprednisolone at a dose of 1 mg/kg every 12 hours (low-dose group) and 1000 mg/day pulse therapy for 3 days following 1 mg/kg methylprednisolone every 12 hours (high-dose group). In this randomized clinical trial, patients with mild to moderate ARDS due to COVID-19 were randomly assigned to receive either low-dose (n = 47) or high-dose (n = 48) intravenous methylprednisolone regimens. Two groups were matched for age, gender, body mass index (BMI), comorbidities, leukocytes, lymphocytes, neutrophil/lymphocyte, platelet, hemoglobin, and inflammatory markers (erythrocyte sedimentation rate [ESR], C-reactive protein [CRP], and ferritin). Both regimens were initiated upon admission and continued for 10 days. The clinical outcome and secondary complications were evaluated. Evaluating in-hospital outcomes, no difference was revealed in the duration of intensive care unit (ICU) stays (5.4 ± 4.6 vs. 4.5 ± 4.9; P = 0.35), total hospital stays (8 ± 3.1 vs. 6.9 ± 3.4; P = 0.1), requirement rate for invasive ventilation (29.2% vs. 36.2%; P = 0.4) or non-invasive ventilation (16.6% vs 23.4%; P = 0.4), and hemoperfusion (16.6% vs 11.3%; P = 0.3) between the low- and high-dose groups. There was no significant difference in fatality due to ARDS (29.2% vs. 38.3%; P = 0.3) and septic shock (4.2% vs. 6.4%; P = 0.3) between the low- and high-dose groups. Patients in the high-dose group had significantly higher bacterial pneumonia co-infection events compared with those in the low-dose group (18.7% vs 10.6%; P = 0.01). The use of adjuvant pulse therapy with intravenous methylprednisolone did not result in improved in-hospital clinical outcomes among patients with mild to moderate ARDS due to COVID-19. A higher risk of bacterial pneumonia should be considered in such cases as receiving a higher dose of steroids.

Capnometry after an inspiratory breath hold, PLAT CO2 , as a surrogate for in mild to moderate pediatric acute respiratory distress syndrome: A feasibility study.

Accurate and reliable noninvasive methods to estimate gas exchange are necessary to guide clinical decisions to avoid frequent blood samples in children with pediatric acute respiratory distress syndrome (PARDS). We aimed to investigate the correlation and agreement between end-tidal measured immediately after a 3-s inspiratory-hold (PLAT CO2 ) by capnometry and measured by arterial blood gases (ABG) in PARDS. Prospective cohort study. Seven-bed Pediatric Intensive Care Unit, Hospital El Carmen de Maipú, Chile. Thirteen mechanically ventilated patients aged ≤15 years old undergoing neuromuscular blockade as part of management for PARDS. None. All patients were in volume-controlled ventilation mode. The regular end-tidal (without the inspiratory hold) was registered immediately after the ABG sample. An inspiratory-hold of 3 s was performed for lung mechanics measurements, recording in the breath following the inspiratory-hold. (PLAT CO2 ). End-tidal alveolar dead space fraction (AVDSf) was calculated as and its surrogate (S)AVDSf as . Measurements of were considered the gold standard. We performed concordance correlation coefficient (ρc), Spearman's correlation (rho), and Bland-Altmann's analysis (mean difference ± SD [limits of agreement, LoA]). Eleven patients were included, with a median (interquartile range) age of 5 (2-11) months. Tidal volume was 5.8 (5.7-6.3) mL/kg, PEEP 8 (6-8), driving pressure 10 (8-11), and plateau pressure 17 (17-19) cm H2 O. Forty-one paired measurements were analyzed. was higher than (52 mmHg [48-54] vs. 42 mmHg [38-45], p < 0.01), and there were no significant differences with PLAT CO2 (50 mmHg [46-55], p > 0.99). The concordance correlation coefficient and Spearman's correlation between and PLAT CO2 were robust (ρc = 0.80 [95% confidence interval [CI]: 0.67-0.90]; and rho = 0.80, p < 0.001.), and for were weak and strong (ρc = 0.27 [95% CI: 0.15-0.38]; and rho = 0.63, p < 0.01). The bias between PLAT CO2 and was -0.4 ± 3.5 mmHg (LoA -7.2 to 6.4), and between and was -8.5 ± 4.1 mmHg (LoA -16.6 to -0.5). The correlation between AVDSf and (S)AVDSf was moderate (rho = 0.55, p < 0.01), and the mean difference was -0.5 ± 5.6% (LoA -11.5 to 10.5). This pilot study showed the feasibility of measuring end-tidal CO2 after a 3-s end-inspiratory breath hole in pediatric patients undergoing controlled ventilation for ARDS. Encouraging preliminary results warrant further study of this technique.