Oxygenation In Acute Respiratory Distress Syndrome Research Articles

Is Prone Positioning Worth the Turn in Pediatrics? Unraveling the Oxygenation Mystery in Ventilated Patients with Acute Respiratory Distress Syndrome: An Observational Study Introducing a Novel SF Ratio Method for Non-Invasive Monitoring in Children

Background: Respiratory illnesses are prevalent among children, attributed to factors such as immature immune systems, anatomical variations, and increased susceptibility to infections. Acute respiratory distress syndrome (ARDS) is a significant cause of morbidity and mortality, necessitating various forms of respiratory support in pediatric intensive care units (PICUs). Prone positioning has emerged as a strategy to improve oxygenation in ARDS, but its effectiveness and correlation with non-invasive monitoring parameters remain underexplored.
 Subjects and Methods: This prospective observational study, conducted in the PICU of Dr. B.C Roy PGIPS, Kolkata, aimed to assess the impact of prone ventilation on oxygenation in children diagnosed with ARDS. The study, spanning 18 months, included 40 patients aged 3 months to 12 years requiring mechanical ventilation. Parameters such as oxygenation index (OI), oxygen saturation index (OSI), PF ratio, and SF ratio were monitored at different time points during supine and prone ventilation. Prone positioning's effectiveness was evaluated based on improvements in these parameters.
 Results: The study revealed a significant improvement in oxygenation status after four hours of prone ventilation compared to supine ventilation. Oxygenation index, OSI, SF ratio, and PF ratio showed statistically significant changes favoring prone positioning. A strong positive correlation between SF ratio and PF ratio was observed at various time points, emphasizing the potential of SF ratio as a non-invasive alternative. Responders and non-responders to prone positioning were identified based on predefined criteria, highlighting individual variability in treatment response.
 Conclusion: Prone ventilation demonstrated significant improvements in oxygenation parameters in children with ARDS. The study supports the use of non-invasive SF ratio as a reliable substitute for PF ratio, simplifying monitoring without invasive arterial sampling. This finding has implications for improving ARDS management strategies in pediatric patients, offering a less cumbersome alternative for assessing oxygenation status.

Utility of Pulse Oximetry Oxygen Saturation (SpO2) with Incorporation of Positive End-Expiratory Pressure (SpO2 ∗10/FiO2 ∗PEEP) for Classification and Prognostication of Patients with Acute Respiratory Distress Syndrome.

Background Conventionally, PaO2/FiO2 (P/F ratio) has been used to categorize severity of acute respiratory distress syndrome (ARDS) and prognostication of outcome. Recent literature has shown that incorporation of positive end-expiratory pressure (PEEP) into the P/F ratio (PaO2∗10/FiO2∗PEEP or P/FP∗10) has a much better prognostic ability in ARDS as compared to P/F ratio. The aim of this study was to correlate SpO2∗10/FiO2∗PEEP (S/FP∗10) to PaO2∗10/FiO2∗PEEP (P/FP∗10) and evaluate the utility of S/FP∗10 as a reliable noninvasive indicator of oxygenation in ARDS to avoid repeated arterial blood sampling. Aim To evaluate if pulse oximetry is a reliable indicator of oxygenation in ARDS patients by calculating SpO2∗10/FiO2∗PEEP (S/FP∗10). The primary objective was to determine the correlation of S/FP∗10 to P/FP∗10 ratio in ARDS patients. The secondary objective was to determine the cut-off value of S/FP∗10 ratio to predict severe ARDS and survival. Methods Patients aged 18–80 years on invasive mechanical ventilation (MV) diagnosed with ARDS as defined by the Berlin definition were included. The values of PaO2, FiO2, and SpO2 were collected at three different time points. They were at baseline, i.e., after intubation and initiation of MV (within one hour of intubation), day one (1–24 hours of MV), and day three (48–72 hours of MV). The primary outcome was survival at the end of intensive care unit (ICU) stay. Results A total of 85 patients with ARDS on invasive MV were included. The data points were obtained at baseline, day one, and day three of MV. S/FP∗10 ratio has an excellent correlation to P/FP∗10 ratio at baseline and day three of invasive MV (r = 0.831 and 0.853, respectively; p < 0.001) and has a strong correlation on day one of invasive MV (r = 0.733, p < 0.001). S/FP∗10 ratio ≤116 at baseline has excellent discriminant function to be categorized as severe ARDS as per Berlin definition (AUC: 0.925, p < 0.001, 90% sensitivity, 93% specificity, CI: [0.862–0.988]). The increase in S/FP∗10 ratio by ≥64.40 from baseline to day three of MV is a good predictor of survival (AUC: 0.877, p < 0.001, 73.5% sensitivity, 97% specificity, CI: [0.803–0.952]). Conclusion S/FP∗10 has a strong correlation to P/FP∗10 in ARDS patients. S/FP∗10 ≤116 has an excellent discriminant function to be categorized as severe ARDS. The S/FP∗10 ratio on day three of MV and the change in S/FP∗10 ratio from baseline and day one to day three of MV are good predictors of survival in ARDS patients. This trial is registered with CTRI/2020/04/024940.

Impact of Bilateral Infiltrates on Inflammatory Biomarker Levels and Clinical Outcomes of Children With Oxygenation Defect.

The 2015 definition for pediatric acute respiratory distress syndrome did not require the presence of bilateral infiltrates. We tested the hypothesis that pediatric patients meeting oxygenation criteria for pediatric acute respiratory distress syndrome but without bilateral infiltrates would have different inflammatory biomarker levels and clinical outcomes than those with bilateral infiltrates. Secondary analysis of a prospective cohort study. Twenty-two PICUs. Four-hundred forty-six patients age 2 weeks to 17 years intubated for respiratory failure with oxygenation index greater than or equal to 4 or oxygenation saturation index greater than or equal to 5 on the day of intubation or the day after. None. Patients with bilateral infiltrates, either on the day of intubation or within the following 2 days, were compared with children who never developed bilateral infiltrates. Two analyses were performed to test 1) whether bilateral infiltrates are associated with elevated interleukin-1 receptor antagonist or interleukin-8 and 2) whether bilateral infiltrates are associated with worse clinical outcomes. Patients with bilateral infiltrates more often had a primary diagnosis of pneumonia (41% vs 28%; p = 0.02) and less often asthma (8% vs 23%; p < 0.01). After controlling for age, gender, and primary diagnosis, interleukin-1 receptor antagonist was higher on study days 1 and 2 in patients with bilateral infiltrates. There was no difference in interleukin-8 levels. After adjusting for age, gender, Pediatric Risk of Mortality score, and severity of oxygenation defect, presence of bilateral infiltrates was associated with longer duration of mechanical ventilation in survivors (hazard ratio, 0.64; 95% CI, 0.49-0.82; p < 0.01); this association was independent of primary diagnosis. Overall mortality was 9%; mortality was higher in those without bilateral infiltrates (14% vs 8%; p = 0.04). Children meeting pediatric acute respiratory distress syndrome oxygenation criteria with bilateral infiltrates on chest radiograph experience a more intense early inflammatory response. Bilateral infiltrates are associated with longer time on the ventilator independent of oxygenation defect severity.

Acute Respiratory Distress Syndrome Following Pediatric Trauma: Application of Pediatric Acute Lung Injury Consensus Conference Criteria.

To assess the incidence, severity, and outcomes of pediatric acute respiratory distress syndrome following trauma using Pediatric Acute Lung Injury Consensus Conference criteria. Retrospective cohort study. Level 1 pediatric trauma center. Trauma patients less than or equal to 17 years admitted to the ICU from 2009 to 2017. None. We queried electronic health records to identify patients meeting pediatric acute respiratory distress syndrome oxygenation criteria for greater than or equal to 6 hours and determined whether patients met complete pediatric acute respiratory distress syndrome criteria via chart review. We estimated associations between pediatric acute respiratory distress syndrome and outcome using generalized linear Poisson regression adjusted for age, injury mechanism, Injury Severity Score, and serious brain and chest injuries. Of 2,470 critically injured children, 103 (4.2%) met pediatric acute respiratory distress syndrome criteria. Mortality was 34.0% among pediatric acute respiratory distress syndrome patients versus 1.7% among patients without pediatric acute respiratory distress syndrome (adjusted relative risk, 3.7; 95% CI, 2.0-6.9). Mortality was 50.0% for severe pediatric acute respiratory distress syndrome at onset, 33.3% for moderate, and 30.5% for mild. Cause of death was neurologic in 60.0% and multiple organ failure in 34.3% of pediatric acute respiratory distress syndrome nonsurvivors versus neurologic in 85.4% of nonsurvivors without pediatric acute respiratory distress syndrome (p = 0.001). Among survivors, 77.1% of pediatric acute respiratory distress syndrome patients had functional disability at discharge versus 30.7% of patients without pediatric acute respiratory distress syndrome patients (p < 0.001), and only 17.5% of pediatric acute respiratory distress syndrome patients discharged home without ongoing care versus 86.4% of patients without pediatric acute respiratory distress syndrome (adjusted relative risk, 1.5; 1.1-2.1). Incidence and mortality associated with pediatric acute respiratory distress syndrome following traumatic injury are substantially higher than previously recognized, and pediatric acute respiratory distress syndrome development is associated with high risk of poor outcome even after adjustment for underlying injury type and severity.

A CASE OF HEMORRHAGE RESCUED BY EXTRACORPOREAL MEMBRANE OXYGENATION

SESSION TITLE: Wednesday Fellows Case Report Posters SESSION TYPE: Fellow Case Report Posters PRESENTED ON: 10/23/2019 09:45 AM - 10:45 AM INTRODUCTION: Diffuse alveolar hemorrhage (DAH) is a well-known complication of many disease processes including vasculitides. DAH secondary to vasculitis, however rare, is one of the most devastating presentations of vasculidities carrying a substantial mortality. A significant percentage of patients with DAH progress to acute respiratory distress syndrome (ARDS) requiring mechanical ventilation. Venovenous extracorporeal membrane oxygenation (VV ECMO) has been described to improve oxygenation in ARDS while underlying etiologies are addressed. The role of VV ECMO in DAH secondary to vasculitis is unclear. CASE PRESENTATION: A 37-year-old woman presented with severe ARDS. In the preceding two weeks, she experienced polyarthralgias and a lower extremity rash. She presented to the emergency department after developing hemoptysis which necessitated intubation. On presentation to the intensive care unit, she was afebrile and had an oxygen saturation of 95% on an FiO2 of 1. Of note, the patient had non-blanching, palpable, hemorrhagic bullae. Lab-work was notable for a white blood cell count of 13,600, a hemoglobin of 8.4 g/dL, a PaO2/FiO2 (P/F) ratio of 92, and urinalysis with protein and dysmorphic red blood cells. Computed tomography of the chest demonstrated diffuse infiltrates sparing the periphery. She was paralyzed and placed in a prone position for severe ARDS. She was started on pulse-dose steroids and on plasma exchange for suspected DAH. On day three, her P/F ratio was 61 and she was placed on VV ECMO. Bronchoscopy was performed with sequentially bloodier returns on alveolar lavage. Further workup revealed negative bacterial cultures, a positive ANA titer of 1:320, a C-ANCA titer of 1:40, and an elevated PR3 antibody. The patient was diagnosed with granulomatosis with polyangiitis and was started on cyclophosphamide. She was decannulated from ECMO after four days, extubated two days thereafter, and was discharged from the hospital in her premorbid state. DISCUSSION: The causes of DAH are varied but are commonly due to autoimmune phenomena. The current evidence for use of ECMO in DAH is limited to case reports and case series. Before the more widespread deployment of extracorporeal support, the treatment of respiratory failure from DAH was limited to aggressive ventilator management and immunomodulating medications. Despite progress in immunosuppressive therapy, the mortality for DAH remains unacceptably high. The deployment of ECMO may provide enough time with sufficient oxygenation for the causes of DAH to be addressed. CONCLUSIONS: Though there is a dearth of high-quality evidence justifying the use of ECMO in DAH, our case demonstrates that VV ECMO can be used successfully to temporize the hypoxemia in DAH. This measure could provide the time necessary for immunosuppression to take effect and reduce overall mortality from the most devastating consequence of vasculitis. Reference #1: Park M. S. (2013). Diffuse alveolar hemorrhage. Tuberculosis and respiratory diseases, 74(4), 51-62. Reference #2: Guo, Z., Li, X., Jiang, L. Y., & Xu, L. F. (2009). Extracorporeal membrane oxygenation for the management of respiratory failure caused by diffuse alveolar hemorrhage. The journal of extra-corporeal technology, 41(1), 37-40. Reference #3: West S, Arulkumaran N, Ind PW, Pusey CD. (2013). Diffuse Alveolar Haemorrhage in ANCA-associated Vasculitis. Internal Medicine, 52(1):5-13. DISCLOSURES: No relevant relationships by Lisa Daniels, source=Web Response No relevant relationships by Joshua Detelich, source=Web Response No relevant relationships by Maxwell Hockstein, source=Web Response

Vasopressin Receptor Expression Reveals Role of Endogenous Vasopressin in Ameliorating Acute Lung Injury in Pig Models of Pulmonary Hypertension

Acute lung injury (ALI) that evolves into acute respiratory distress syndrome (ARDS) is a critical care management challenge with 30–40% mortality. Despite the beneficial ability of pharmacological doses of vasopressin (VP)to elevate blood pressure without worsening pulmonary hypertension (PHN) in severe septic shock ARDS, circulating VP levels (not necessarily indicative of local tissue VP action) remain relatively low and it is unclear whether VP has a physiological role in maintaining pulmonary blood flow and oxygenation in ARDS. We hypothesized that if endogenous VP has an important role in ameliorating ALI, vascular VP receptor mRNA expression will increase within hours after initial ALI insult in order to replenish spent receptors that are degraded when activated by endogenous VP.Anesthetized Yorkshire cross pigs(n=36, 7.9 ± 0.2 kg body weight) were used to examine pulmonary hemodynamics in ALI without the confounding effects of systemic hypotension. PHN was induced by either disrupting the lung alveolar‐capillary interface with oleic acid (OA; 0.1 ml/kg iv, n=14) or by causing endothelial dysfunction with endotoxin (ETX; up to 35,000 units iv, n=16). ALI pigs had elevated pulmonary to systemic vascular resistance ratios (PVR/SVR: OA = 0.48 ± 0.07 and ETX = 0.48 ±0.04) compared to controls (0.20 ± 0.01, n=6). Mean arterial pressure was constant (60±4 mm Hg in all groups). ALI was managed with supplemental oxygen with or without mesenchymal stem cells to facilitate lung tissue repair. Within 2 hours after treatment, PVR/SVR began to return towards baseline in the ETX group but remained elevated in the OA group. This provided a range of pulmonary vasoconstriction states to compare against changes in plasma VP, pituitary VP content, and the mRNA expression of VP, V1aR, V1bR, and V2R receptors in pulmonary, carotid, renal, celiac, and mesenteric arteries, and aorta collected12 to 16 hours after initial ALI. Stepwise multiple regression revealed that PVR/SVR at 2–4 hours of established lung injury was positively correlated with V1aR expression in the aorta and mesenteric artery and V2R expression in the pulmonary and renal arteries, and negatively correlated with V2R expression in the aorta and celiac arteries (r2=0.88, p&lt;0.0001). Results are consistent with endogenous VP responding to pulmonary hypertension in ALI via a pulmonary V2R mediated vasodilatory counter effect, in the face of V1aR mediated vasoconstriction in other vascular beds, to maintain pulmonary blood flow and improve blood oxygenation.Support or Funding InformationThis project was supported by the US Army Medical Command. The views expressed in this abstract are those of the authors and do not reflect the official policy or position of the Department of the Army, Department of Defense, or the U.S. GovernmentThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

The Use of GMP-Produced Bone Marrow-Derived Stem Cells in Combination with Extracorporeal Membrane Oxygenation in ARDS: An Animal Model

Acute respiratory distress syndrome (ARDS) is the result of a wide variety of disorders, which can be associated with different clinical disorders or systemic diseases directly affecting the lungs. Currently, the only existing therapy is limited to supportive care. In a 6 hour pilot study, we analyzed the use of the combination of both stem cell and extracorporeal membrane oxygenation (ECMO) strategies to prevent or treat severe lung injury. A total of 11 sheep were used. Five sheep received Escherichia coli endotoxin as a control group (group 1). Three sheep that received E. coli endotoxin were treated with veno-venous ECMO support in group 2. In group 3, 3 sheep received a dose of clinical grade good manufacturing practice (GMP)-produced MultiPotent Adult Progenitor cells (MAPC) intratracheally after the end of the infusion of E. coli endotoxin, followed by ECMO support. The respiratory parameters by means of blood gas results, measurements of lung injury, inflammatory responses, and integrity of the alveolar capillary barrier after the infusion of these cells were analyzed. Our data suggest that the combination of ECMO and stem cell therapy showed better histopathologic changes with less inflammation. We believe that the combination of stem cells with the ECMO treatment may be useful in future studies investigating the diagnosis, treatment, and prevention of ARDS.

Comparison of inhaled milrinone, nitric oxide and prostacyclin in acute respiratory distress syndrome.

AIMTo evaluate the safety and efficacy of inhaled milrinone in acute respiratory distress syndrome (ARDS).METHODSOpen-label prospective cross-over pilot study where fifteen adult patients with hypoxemic failure meeting standard ARDS criteria and monitored with a pulmonary artery catheter were recruited in an academic 24-bed medico-surgical intensive care unit. Random sequential administration of iNO (20 ppm) or nebulized epoprostenol (10 μg/mL) was done in all patients. Thereafter, inhaled milrinone (1 mg/mL) alone followed by inhaled milrinone in association with inhaled nitric oxide (iNO) was administered. A jet nebulization device synchronized with the mechanical ventilation was use to administrate the epoprostenol and the milrinone. Hemodynamic measurements and partial pressure of arterial oxygen (PaO2) were recorded before and after each inhaled therapy administration.RESULTSThe majority of ARDS were of pulmonary cause (n = 13) and pneumonia (n = 7) was the leading underlying initial disease. Other pulmonary causes of ARDS were: Post cardiopulmonary bypass (n = 2), smoke inhalation injury (n = 1), thoracic trauma and pulmonary contusions (n = 2) and aspiration (n = 1). Two patients had an extra pulmonary cause of ARDS: A polytrauma patient and an intra-abdominal abscess Inhaled nitric oxide, epoprostenol, inhaled milrinone and the combination of inhaled milrinone and iNO had no impact on systemic hemodynamics. No significant adverse events related to study medications were observed. The median increase of PaO2 from baseline was 8.8 mmHg [interquartile range (IQR) = 16.3], 6.0 mmHg (IQR = 18.4), 6 mmHg (IQR = 15.8) and 9.2 mmHg (IQR = 20.2) respectively with iNO, epoprostenol, inhaled milrinone, and iNO added to milrinone. Only iNO and the combination of inhaled milrinone and iNO had a statistically significant effect on PaO2.CONCLUSIONWhen comparing the effects of inhaled NO, milrinone and epoprostenol, only NO significantly improved oxygenation. Inhaled milrinone appeared safe but failed to improve oxygenation in ARDS.

Can we optimize long-term outcomes in acute respiratory distress syndrome by targeting normoxemia?

Since its original description in 1967, acute respiratory distress syndrome (ARDS) has been recognized as a devastating condition associated with significant morbidity and mortality. Advances in critical care medicine and ARDS management have led to a substantial increase in the number of ARDS survivors. Long-term cognitive impairment after critical illness is a significant public health concern. ARDS survivors frequently experience long-term cognitive impairment, as well as physical impairment, psychiatric morbidity, and reduced health-related quality of life. At present, no intensive care unit-based intervention has been proven to reduce the risk of long-term cognitive impairment after ARDS. To address the urgent need to identify strategies to preserve long-term health, investigators have advocated the measurement of short- and long-term outcomes in clinical trials. Maintaining adequate oxygen delivery to preserve organ function is of vital importance in ARDS management. The optimal target range for arterial oxygenation in ARDS remains unknown, due in part to the challenge to maintain adequate tissue oxygenation and to minimize harm, such as oxygen toxicity. An approach targeted to subnormal oxygenation values (partial pressure of arterial oxygen, 55-80 mm Hg) has emerged as a means to accomplish these aims. In this perspective, we critically evaluate this strategy from short- and long-term perspectives, with a focus on the potential long-term cognitive effects of the strategy. We conclude with a proposal to consider resetting the target range for arterial oxygenation higher (85-110 mm Hg) as a potential strategy to improve the long-term outcomes of ARDS survivors.

Update in acute respiratory distress syndrome.

Acute respiratory distress syndrome (ARDS) is characterized by permeability pulmonary edema and refractory hypoxemia. Recently, the new definition of ARDS has been published, and this definition suggested severity-oriented respiratory treatment by introducing three levels of severity according to PaO2/FiO2 and positive end-expiratory pressure. Lung-protective ventilation is still the key of better outcome in ARDS. Through randomized trials, short-term use of neuromuscular blockade at initial stage of mechanical ventilation, prone ventilation in severe ARDS, and extracorporeal membrane oxygenation in ARDS with influenza pneumonia showed beneficial efficacy. However, ARDS mortality still remains high. Therefore, early recognition of ARDS modified risk factors and the avoidance of aggravating factors during the patient's hospital stay can help decrease its development. In addition, efficient antifibrotic strategies in late-stage ARDS should be developed to improve the outcome.

Prone positioning for acute respiratory distress syndrome in the surgical intensive care unit: Who, when, and how long?

Background. We evaluated the effects of prone positioning (PP) on surgery and trauma patients with acute respiratory distress syndrome (ARDS). Methods. Patients with ARDS were studied. Exclusion criteria were contraindications to PP. Patients were evaluated in the supine position and after being turned to the PP. After 6 hours, patients were returned to the supine position for 3 hours. One hour after each position change, arterial and mixed venous blood was drawn and analyzed for blood gases and pH, and hemodynamics were measured. Results. Over 20 months, 27 patients met the criteria, and 20 of the patients were entered into the study. On day 1, 18 of 20 patients (90%) responded with an increase in PaO2 during PP. On day 2, 16 of 17 patients (94%) responded; on day 3, 15 of 16 patients responded (94%); on day 4, 11 of 13 patients responded (85%); on day 5, 8 of 8 patients responded (100%); and on day 6, 4 of 5 patients responded (80%). Pao2/Fio2 and Qs/Qt were significantly improved (P <.05) during PP. There were 91 periods of PP, lasting 10.3 ± 1.2 hours. Of 91 changes to PP, 78 changes (86%) resulted in an improvement in Pao2/Fio2 of more than 20%. Conclusions. PP improves oxygenation in ARDS for 6 days with few complications. (Surgery 2000;128:708-16.)

Extravascular lung water and acute respiratory distress syndrome--oxygenation and outcome.

We studied eleven consecutive patients to assess the influence of extravascular lung water on clinical outcome. All patients were mechanically ventilated using a standardized protocol. Inspired oxygen concentration was adjusted to an initial target PaO2 of greater than 8.0 kPa (60.8 mmHg). All patients received inhaled nitric oxide (NO) at a concentration of 20 ppm. Extravascular lung water index (EVLWI) was measured by a dual indicator technique (COLD Z-021 monitoring system, Pulsion, Munich, Germany). Patients were managed with fluids and inotropes according to a standard protocol. Median age was 45 (range 27-60) years, mean APACHE II score on admission 31 (range 17-36), duration of mechanical ventilation 15 (range 6-28) days, mean admission Murray lung injury score 2.5 (range 2-3) and admission EVLWI 20.8 (range 8.7 to 54.7) ml.kg-1. The only variables independently predictive of PaO2/FiO2 ratio were serum albumin (B = 1.7 +/- 1.61) and EVLWI (B = -2.1 +/- 0.47), r2 = 0.33, P < 0.0001. In severe ARDS, (PaO2/FiO2 < 150 mmHg), mean EVLWI was 24.4 (22.4 to 26.4, 95% confidence intervals) ml.kg-1 compared with 15.1 (12.2 to 18.0) ml.kg-1 during moderate ARDS (P < 0.001). Serum albumin likewise differed, 29.4 (27.6 to 31.2) vs 35.1 (31.8 to 38.4) g.l-1, P < 0.005. PAOP was higher during periods of poor oxygenation, 12.7 (11.9 to 13.5) vs 9.3 (7.9 to 10.7) mmHg, P < 0.001. The four survivors had greater initial EVLWI than non-survivors, 31 (24.1 to 37.9) vs 20.7 (16.0 to 25.4) ml.kg-1, P = 0.034 and showed a greater reduction in lung water, 15.2 (9.3 to 21.1) vs 5.4 (2.1 to 8.7) ml.kg-1, P = 0.013.