Degree Of Hypoxemia Research Articles

Impact of mechanical power on ICU mortality in ventilated critically ill patients: a retrospective study with continuous real-life data

BackgroundOver the past decade, numerous studies on potential factors contributing to ventilation-induced lung injury have been carried out. Mechanical power has been pointed out as the parameter that encloses all ventilation-induced lung injury-contributing factors. However, studies conducted to date provide data regarding mechanical power during the early hours of mechanical ventilation that may not accurately reflect the impact of power throughout the period of mechanical ventilatory support on intensive care unit mortality.MethodsRetrospective observational study conducted at a single center in Spain. Patients admitted to the intensive care unit, > o = 18 years of age, and ventilated for over 24 h were included. We extracted the mechanical power values throughout the entire mechanical ventilation in controlled modes period from the clinical information system every 2 min. First, we calculate the cutoff-point for mechanical power beyond which there was a greater change in the probability of death. After, the sum of time values above the safe cut-off point was calculated to obtain the value in hours. We analyzed if the number of hours the patient was under ventilation with a mechanical power above the safe threshold was associated with intensive care unit mortality, invasive mechanical ventilation days, and intensive care unit length of stay. We repeated the analysis in different subgroups based on the degree of hypoxemia and in patients with SARS CoV-2 pneumonia.ResultsThe cut-off point of mechanical power at with there is a higher increase in intensive care unit mortality was 18 J/min. The greater the number of hours patients were under mechanical power > 18 J/min the higher the intensive care unit mortality in all the study population, in patients with SARS CoV-2 pneumonia and in mild to moderate hypoxemic respiratory failure. The risk of death in the intensive care unit increases 0.1% for each hour with mechanical power exceeding 18 J/min. The number of hours with mechanical power > 18 J/min also affected the days of invasive mechanical ventilation and intensive care unit length of stay.ConclusionsThe number of hours with mechanical power > 18 J/min is associated with mortality in the intensive care unit in critically ill patients. Continuous monitoring of mechanical power in controlled modes using an automated clinical information system could alert the clinician to this risk.

Hypoxic irreversible brain cells damage, associated risk factors and antihypoxants

It is reported that in the final stage of many diseases the immediate cause of biological death in humans and warm-blooded animals is hypoxic irreversible damage to brain cells. This explains the fact that to prevent biological death in all critical conditions without exception, inhalation with breathing gases containing oxygen has long been successfully used. This is also why oxygenation of the blood is considered one of the main conditions for preserving human life in all critical situations and forms the basis of emergency medical care in the intensive care unit. However, inhalation of oxygen gas and increasing blood oxygen saturation should be carried out as early as possible, and more precisely - before the onset of the stage of hypoxic irreversible damage in brain cells. The fact is that after the onset of irreversible damage brain cells die even in the presence of oxygen. In this connection, the mechanisms of adaptation of the organism to oxygen deficiency play a great role for longer preservation of brain cells viability and human life in conditions of hypoxemia. In order to increase resistance to hypoxemia, antihypoxants are traditionally used. But they can preserve the viability of brain cells not always, but only if they are introduced into the body before the onset of hypoxic irreversible damage to brain cells and in the case of unused reserves of adaptation to hypoxemia in the body. Risk factors of hypoxic irreversible damage of brain cells are indicated, among which excessively long duration of hypoxemia and hyperthermia are emphasized. It is shown that the most important circumstance for the development of hypoxic irreversible damage of brain cells is not so much the degree of hypoxemia as the degree of hypoxia of brain tissue and its duration, which exceeds the period of human resistance to hypoxia. It has been shown that human resistance to hypoxia can be assessed using the Stange test. It has been reported that fever and local cerebral hyperthermia decrease, and hibernation and local cerebral hypothermia increase, the resistance of brain cells to hypoxia. In this regard, recommendations not only to eliminate fever and local inflammatory processes in the head, but also recommendations to reduce brain temperature are highly appropriate to improve resistance to hypoxia. It is pointed out that among the methods of local therapeutic hypothermia, targeted temperature management is the most advanced. In addition, it is reported that in recent years a new group of promising antihypoxants - alkaline solutions of hydrogen peroxide - has been created. It is shown that hydrogen peroxide is able to decompose very quickly into water and oxygen gas under the action of catalase, which is found in all tissues. The peculiarities of using alkaline solutions of hydrogen peroxide as antihypoxants we all have to study in the future.

A BAYESIAN MACHINE LEARNING APPROACH FOR ESTIMATING HETEROGENEOUS SURVIVOR CAUSAL EFFECTS: APPLICATIONS TO A CRITICAL CARE TRIAL.

Assessing heterogeneity in the effects of treatments has become increasingly popular in the field of causal inference and carries important implications for clinical decision-making. While extensive literature exists for studying treatment effect heterogeneity when outcomes are fully observed, there has been limited development in tools for estimating heterogeneous causal effects when patient-centered outcomes are truncated by a terminal event, such as death. Due to mortality occurring during study follow-up, the outcomes of interest are unobservable, undefined, or not fully observed for many participants in which case principal stratification is an appealing framework to draw valid causal conclusions. Motivated by the Acute Respiratory Distress Syndrome Network (ARDSNetwork) ARDS respiratory management (ARMA) trial, we developed a flexible Bayesian machine learning approach to estimate the average causal effect and heterogeneous causal effects among the always-survivors stratum when clinical outcomes are subject to truncation. We adopted Bayesian additive regression trees (BART) to flexibly specify separate mean models for the potential outcomes and latent stratum membership. In the analysis of the ARMA trial, we found that the low tidal volume treatment had an overall benefit for participants sustaining acute lung injuries on the outcome of time to returning home but substantial heterogeneity in treatment effects among the always-survivors, driven most strongly by biologic sex and the alveolar-arterial oxygen gradient at baseline (a physiologic measure of lung function and degree of hypoxemia). These findings illustrate how the proposed methodology could guide the prognostic enrichment of future trials in the field.

Anesthetic management of a case of pulmonary alveolar proteinosis for whole lung lavage

Abstract Pulmonary Alveolar Proteinosis (PAP) is a rare disease of the lungs characterized by deposition of lipo-proteinaceous material in the alveoli. This leads to reduced lung compliance and V/Q mismatch, causing respiratory failure. Patients with PAP may be posted for Whole Lung Lavage (WLL) under anesthesia, which is a challenging case for anesthetists. Preexisting respiratory failure is complicated by requirement of single lung ventilation with the help of double lumen tube during the procedure. Intraoperative ventilation is difficult and is managed with blood gas and airway pressure monitoring. Some degree of hypoxemia and hypercapnia may have to be tolerated. Large volumes of fluid are instilled into the lung which may cause hypothermia, hypervolemia, and electrolyte disturbances. These patients frequently require elective ventilation and intensive care admission in the postoperative period. We report the case of a young woman with PAP, posted for unilateral WLL under anesthesia. We wish to highlight the possible challenges posed by this case and how to conduct a safe anesthesia for this patient.

A Focused Review of the Initial Management of Patients with Acute Respiratory Distress Syndrome.

At present, the management of patients with acute respiratory distress syndrome (ARDS) largely focuses on ventilator settings to limit intrathoracic pressures by using low tidal volumes and on FiO2/PEEP relationships to maintain optimal gas exchange. Acute respiratory distress syndrome is a complex medical disorder that can develop in several primary acute disorders, has a rapid time course, and has several classifications that can reflect either the degree of hypoxemia, the extent of radiographic involvement, or the underlying pathogenesis. The identification of subtypes of patients with ARDS would potentially make precision medicine possible in these patients. This is a very difficult challenge given the heterogeneity in the clinical presentation, pathogenesis, and treatment responses in these patients. The analysis of large databases of patients with acute respiratory failure using statistical methods such as cluster analysis could identify phenotypes that have different outcomes or treatment strategies. However, clinical information available on presentation is unlikely to separate patients into groups that allow for secure treatment decisions or outcome predictions. In some patients, non-invasive positive pressure ventilation provides adequate support through episodes of acute respiratory failure, and the development of specialized units to manage patients with this support might lead to the better use of hospital resources. Patients with ARDS have capillary leak, which results in interstitial and alveolar edema. Early attention to fluid balance in these patients might improve gas exchange and alter the pathophysiology underlying the development of severe ARDS. Finally, more attention to the interaction of patients with ventilators through complex monitoring systems has the potential to identify ventilator dyssynchrony, leading to ventilator adjustments and potentially better outcomes. Recent studies with COVID-19 patients provide tentative answers to some of these questions. In addition, expert clinical investigators have analyzed the promise and difficulties associated with the development of precision medicine in patients with ARDS.

A case series evaluating the effect of esmolol therapy to treat hypoxemia in COVID-19 patients on VV-ECMO.

When COVID-19 ARDS abolishes pulmonary function, VV-ECMO can provide gas exchange. If oxygenation remains insufficient despite maximal VV-ECMO support, the addition of esmolol has been proposed. Conflict exists, however, as to the oxygenation level which should trigger beta-blocker initiation. We evaluated the effect of esmolol therapy on oxygenation and oxygen delivery in patients with negligible native lung function and various degrees of hypoxemia despite maximal VV-ECMO support. We found that, in COVID-19 patients with negligible pulmonary gas exchange, the generalized use of esmolol administration to raise arterial oxygenation by slowing heart rate and thereby match native cardiac output to maximal attainable VV ECMO flows actually reduces systemic oxygen delivery in many cases.

Risk factors of second ventilator-associated pneumonia in trauma patients: a retrospective cohort study.

Ventilator acquired pneumonia (VAP) is a frequent and serious complication in ICU. Second episodes of VAP are common in trauma patients and may be related to severity of underlying conditions, treatment or bacterial factors of the first VAP. The aim of this study was to identify risk factors of second VAP episodes in trauma injured patients (defined as the development of a new pulmonary infection during or remotely following the first episode). This is a single-center, retrospective cohort study of trauma injured patients who underwent a first episode of VAP between January 1, 2013 and December 31, 2020 at Beaujon Hospital. A total of 533 patients with a first episode of VAP were analyzed, mostly with head and/or thoracic traumatic injury. A second episode of VAP occurred in one hundred sixty-seven patients (31.3%). The main risk factors found was the degree of hypoxemia at the time of the first episode [PaO2/FiO2 ratio 100-200, OR 3.12 (1.77-5.69); < 100, OR 5.80 (2.70-12.8)] and severe traumatic brain injury characterized by an initial GCS ≤ 8 [OR 1.65 (1.01-2.74)]. Depth of hypoxemia during the first VAP episode and severity of the initial brain injury are the main risk factors for VAP second episode in trauma injured patients.

Oxygen Delivery Devices in Hypoxemic Respiratory Failure

Oxygen therapy by appropriate oxygen delivery device (ODD) at different stages is an essential part of hypoxemic respiratory failure management. The choice of ODDs depends on the degree of hypoxemia, precision of delivery, patient comfort, risk of transmission of infection to Health Care Worker (HCW), and the cost. Management of hypoxemic respiratory failure depends on underlying etiology and pathophysiology of the disease process. Study from the current global pandemic of novel coronavirus disease 2019 (COVID-19) showed that the severity of hypoxemia is independently associated with in-hospital mortality and can be an important predictor risk of admission to intensive care unit. In this review, we will discuss the different ODDs, their indication for use along with the advantages and disadvantages.

WHYETT: A STUDY TO UNDERSTAND CLINICIAN DECISION MAKING FOR INTUBATION

TYPE: Abstract TOPIC: Critical Care PURPOSE: Many patients with COVID19 develop respiratory failure requiring mechanical ventilation. One unique clinical feature this population demonstrates is “Silent Hypoxemia:” wherein patients’ symptoms and degree of hypoxemia are discordant. Thus, we hypothesized that decisions to intubate patients with COVID19 are based on different factors than non-COVID19 patients. We sought to identify reasons given by clinicians who intubated COVID19 patients. METHODS: Between February and June 2021, we conducted a manual daily review of all intubations at two tertiary care hospitals in NY. Surveys were sent to responsible clinicians within 24 hours of intubation to minimize recall bias. Surveys prompted clinicians to rank reason(s) for intubation from a list developed via initial interviews. They were also asked whether the patient had COVID19 and if intubation occurred during resuscitation for cardiac arrest. RESULTS: 55 surveys out of 179 were completed. 9 were excluded as resuscitative intubations for cardiac arrest. Primary (most important) reasons given for intubation are displayed in figure 1. CONCLUSIONS: COVID19 patients were intubated primarily for either hypoxemia or increased work of breathing, while non-COVID19 patients were primarily intubated for airway concerns. In many of these cases, airway concern was mostly due to concern about impending mental status impairment with inability to protect airway. An ongoing detailed chart review will further elucidate clinical indications for intubation in COVID19 patients, and will be tested for associations with patient outcomes. CLINICAL IMPLICATIONS: COVID19 patients are intubated for categorially different reasons. Measuring these reasons and associations with outcomes is important for developing guidelines for optimal intubation strategies. DISCLOSURE: Nothing to declare. KEYWORD: Intubation

STUDY OF INFLAMMATORY MARKERS IN HYPOXIC COVID 19 PATIENTS AND CORRELATION WITH DISEASE SEVERITY

Background: COVID-19 is global pandemic affecting mainly a respiratory system and causing hypoxemia in the majority of those been infected. In our study, we aimed to correlate the inflammatory markers with severity of hypoxemia and predicting the significant markers of disease severity. Aims and Objectives:To correlate the inflammatory markers with degree of hypoxemia and To determine the inflammatory markers useful in predicting the disease severity. Materials and Methods:A cross-sectional observational study was conducted in the month of may 2021 in tertiary care hospital chinnaoutpalli near Vijayawada in Andhra Pradesh. The 296 patients diagnosed as COVID-19 positive by real-time Polymerase chain reaction and admitted in our hospital requiring oxygen (hypoxemic) were included. These patients were divided into supplemental oxygen group (SuO2 Group) and non invasive ventilation group (NIV group) and inflammatory markers among these groups were compared. Results: Out of 296 hypoxemic patients, 148 were in ward, requiring SuO2,148 were in ICU requiring NIV. There was significant differences in mean D-dimer (p=0.001), and neutrophil-to-lymphocyte ratio (p=0.012),among NIV and SuO2 group .There was no significant difference in CRP, ferritin. Conclusion: The inflammatory markers are a good guide for predicting the hypoxemia and disease severity. The results concluded Neutrophil-to-Lymphocyte ratio, D-Dimer were effective biomarkers in predicting a severity and prognosis of COVID- 19 patients, but could not establish significant association of serum Ferritin, CRP with disease severity.

A Nomogram-Based Model to Predict Respiratory Dysfunction at 6 Months in Non-Critical COVID-19 Survivors.

ObjectiveTo assess the prevalence of respiratory sequelae of Coronavirus disease 2019 (COVID-19) survivors at 6 months after hospital discharge and develop a model to identify at-risk patients.Patients and MethodsIn this prospective cohort study, hospitalized, non-critical COVID-19 patients evaluated at 6-month follow-up between 26 August, 2020 and 16 December, 2020 were included. Primary outcome was respiratory dysfunction at 6 months, defined as at least one among tachypnea at rest, percent predicted 6-min walking distance at 6-min walking test (6MWT) ≤ 70%, pre-post 6MWT difference in Borg score ≥ 1 or a difference between pre- and post-6MWT oxygen saturation ≥ 5%. A nomogram-based multivariable logistic regression model was built to predict primary outcome. Validation relied on 2000-resample bootstrap. The model was compared to one based uniquely on degree of hypoxemia at admission.ResultsOverall, 316 patients were included, of whom 118 (37.3%) showed respiratory dysfunction at 6 months. The nomogram relied on sex, obesity, chronic obstructive pulmonary disease, degree of hypoxemia at admission, and non-invasive ventilation. It was 73.0% (95% confidence interval 67.3–78.4%) accurate in predicting primary outcome and exhibited minimal departure from ideal prediction. Compared to the model including only hypoxemia at admission, the nomogram showed higher accuracy (73.0 vs 59.1%, P < 0.001) and greater net-benefit in decision curve analyses. When the model included also respiratory data at 1 month, it yielded better accuracy (78.2 vs. 73.2%) and more favorable net-benefit than the original model.ConclusionThe newly developed nomograms accurately identify patients at risk of persistent respiratory dysfunction and may help inform clinical priorities.

Гострий респіраторний дистрес-синдром у дітей. Що нового?

Респіраторний дистрес-синдром у дітей — одна з найскладніших патологій, з якою доводиться стикатися у відділеннях реанімації та інтенсивної терапії. У педіатричній практиці були відсутні конкретні рекомендації щодо діагностики та лікування дітей різних вікових груп. Не було конкретних педіатричних дефініцій для респіраторного дистрес-синдрому дорослих. У 2015 році експертами Погоджувальної конференції з педіатричного гострого респіраторного дистрес-синдрому (ПГРДС) (The Pediatric Acute Lung Injury Consensus Conference) були опубліковані конкретні визначення по ГРДС у дітей, а також подані пріоритетні напрямки для майбутніх досліджень. Було розроблено в цілому 151 рекомендацію, що стосуються розділів, пов’язаних із педіатричним гострим респіраторним дистрес-синдромом: визначення, поширеність та епідеміологія; патофізіологія, супутні захворювання та тяжкість; респіраторна підтримка; легенева, допоміжна і нелегенева терапія; моніторинг; неінвазивна респіраторна підтримка та вентиляція; екстракорпоральні методи лікування; захворюваність і довгострокові результати. У цій статті надані основні розроблені рекомендації та конкретизований ряд позицій, що мають особливості тільки для педіатричного ГРДС. До того ж, визначено ряд відмінностей між гострим респіраторним дистрес-синдромом дорослих та дітей як в його діагностиці, так і в лікуванні. При оцінці оксигенації, рівня гіпоксемії та визначенні тяжкості педіатричного ГРДС були прийняті такі показники, як індекс осксигенації (OI) = (FIO2 × середній тиск в дихальних шляхах (Paw) × 100) / РаО2, та індекс насичення киснем (OSI) = (FIO2 × Paw × 100) / SpO2 [11, 12]. Все це буде оптимізувати та покращувати терапію ГРДС у дітей і в подальшому знижувати показник їх смертності від цієї патології.

Mechanisms of platypnea-orthodeoxia syndrome.

Platypnea orthodeoxia syndrome (POS) is a clinical entity described in the middle of the last century. It is characterized by dyspnea and hypoxemia triggered by standing and relieved with recumbency. The diagnosis is predominately clinical. The degree of hypoxemia is variable; however, the diagnostic criteria include the decrease in arterial oxygen pressure more than 4 mmHg or oxygen saturation more than 5%. Even though many diseases cause this syndrome, there are only two responsible mechanisms, intracardiac, and intrapulmonary shunts. The coexistence of diverse structural and physiological abnormalities joined to gravitational forces that induce blood shunt after standing is crucial in each mechanism. The intracardiac mechanism is characterized by right to left blood shunt through atrial septal communications and, the right atrium pressure could be normal or increased. In addition, some patients have one or more coexistent aortic, spinal, or intracardiac alterations. The intrapulmonary mechanism is less frequent and is caused by parenchymal or vascular pathologies. Transthoracic echocardiogram is the first diagnostic modality; however, understanding the pathophysiology is the key for a rational diagnostic approach and subsequent diagnostic studies. Treatment is possible and effective in the majority of intracardiac mechanisms and some intrapulmonary. This review focuses on the pathophysiologic mechanisms of POS and their diagnostic workup.

IDIOPATHIC PULMONARY ARTERIOVENOUS MALFORMATION: A RARE CAUSE OF DYSPNEA ON EXERTION

TOPIC: Lung Pathology TYPE: Fellow Case Reports INTRODUCTION: Pulmonary arteriovenous malformation (PAVM) is rare cardiopulmonary vascular abnormality caused by the abnormal connection between pulmonary arteries and venous systems, more commonly associated to congenital disorders. More than 80% are congenital, and of these 47%–80% are associated with Osler-Weber-Render disease or hereditary hemorrhagic telangiectasia (HHT). Although most patients are asymptomatic, can cause dyspnea from right-to-left shunt, and the degrees of hypoxemia will be determined by the size of the shunt. PAVM was first described in 1897 by Churton, and even though the prevalence of PAVMs may be 1 in 2600 individuals, the condition is underdiagnosed and poorly understood. PAVMs may be single or multiple in occurrence and the incidence of single PAVMs ranges from 42% to 74%. CASE PRESENTATION: Case of a 48-year-old man with hypertension, GERD, testicular leydig cell tumor status post left orchiectomy and hypogonadism presented to his gastroenterologist with persistent abdominal pain refractory to medication. Upon review of systems, stated progressive dyspnea on exertion of one-year duration after orchiectomy, with associated fatigue. Denied any history of dizziness, syncope, epistaxis, hemoptysis, chest pain, palpitations, or cough. Physical examination was unremarkable and peripheral saturation at 99% at room air. Chest X-Ray with no cardiopulmonary pathology. Given persistent abdominal pain, abdominal CT scan was ordered, and a right lower lung lobe AVM was identified. CT angiography of the chest confirmed the presence of PAVM arising from the peripheral branches of the right pulmonary artery and feeding artery measuring 4mm. Radionuclide perfusion lung scan was compatible with a right to left shunt of 12%. Pulmonary function test done with the 100% oxygen and ABGs showed normal spirometry and estimated a shunt fraction of 15%. Bubble Study with evidence of PAVM. Considering patient is symptomatic he was scheduled for embolization. DISCUSSION: For many years, PAVM has been underdiagnosed and poorly understood, other symptoms include hemoptysis, chest pain, palpitations, epistaxis, and cough. Most patient are asymptomatic, confirmed patients should be screened for cerebral malformation by contrast enhanced head CT scan or magnetic resonance imaging given the high risk of stroke and brain abscess. Treatment must be offered to all symptomatic patients whereas asymptomatic patients should be evaluated on case to case basis. The treatment of choice for PAVMs is embolization, especially if the feeding vessel is larger or equal than 3mm. Follow-up with Thoracic CT Scan at 6–12 months must be performed to detect reperfusion of PAVM and opening of other occult PAVM. CONCLUSIONS: This case is intended to raise medical awareness on possible differential diagnosis of uncommon pulmonary causes of hypoxemia and dyspnea on exertion including pulmonary arteriovenous malformation. REFERENCE #1: Gossage JR, Kanj G. Pulmonary arteriovenous malformations. A state of the art review. Am J Respir Crit Care Med. 1998 Aug;158(2):643-61. REFERENCE #2: Shovlin CL. Pulmonary arteriovenous malformations. Am J Respir Crit Care Med. 2014 Dec 1;190(11):1217-28. REFERENCE #3: Shovlin CL, Condliffe R, Donaldson JW, Kiely DG, Wort SJ; British Thoracic Society. British Thoracic Society Clinical Statement on Pulmonary Arteriovenous Malformations. Thorax. 2017 Dec;72(12):1154-1163. DISCLOSURES: No relevant relationships by Onix Cantres-Fonseca, source=Web Response No relevant relationships by Vanessa Fonseca Ferrer, source=Web Response No relevant relationships by SULIMAR MORALES, source=Web Response

Excellent outcomes with liver transplantation in hepatopulmonary syndrome across pre-transplant PaO2 spectrum

Background & AimsSignificantly worse survival has been reported in patients with hepatopulmonary syndrome (HPS) and partial pressure of arterial oxygen (PaO2) <45 mmHg undergoing liver transplantation. Long-term pre- and post-transplant outcomes based on degree of hypoxaemia were re-examined.MethodsA retrospective analysis of 1,152 HPS candidates listed with an approved HPS model for end-stage liver disease (MELD) exception was performed. A Fine and Gray competing risks model was utilised to evaluate pre-transplant outcomes for PaO2 thresholds of <45, 45 to <60, and ≥60 mmHg. Post-transplant survival was analysed using the Kaplan–Meier method.ResultsPatients with a PaO2 <45 mmHg were significantly more likely to undergo transplantation (hazard ratio [HR] 1.51; 95% CI 1.12–2.03), whereas patients with higher MELD scores had lower hazard of transplant (HR 0.80, 95% CI 0.67–0.95, p = 0.011) and higher hazard of pre-transplant death (HR 2.29, 95% CI 1.55–3.37, p <0.001). Post-transplantation, patients with a PaO2 <45 mmHg had lower survival (p = 0.04) compared with patients with a PaO2 ≥45 to <50 mmHg, with survival curves significantly different at 2.6 years (75% survival compared with 86%) and median survival of 11.5 and 14.1 years, respectively. Cardiac arrest was a more likely (p = 0.025) cause of death for these patients. Cardiac arrest incidence in patients who died with a PaO2 >50 mmHg was 6.2%.ConclusionsPatients with a PaO2 <45 mmHg had a significantly higher rate of transplantation, and higher calculated MELD scores were associated with significantly higher pre-transplant mortality. Although post-transplant survival was lower in patients with a PaO2 <45 mmHg, the median survival was 11.5 years, and survival curves only became significantly different at 2.6 years. This suggests that patients with HPS do benefit from transplantation up to 2–3 years post-transplant regardless of the severity of pre-transplant hypoxaemia.Lay summaryA total of 1,152 patients with hepatopulmonary syndrome listed for liver transplant were analysed. Patients with a low PaO2 <45 mmHg had a high likelihood of transplantation. If associated with advanced liver disease, the mortality risk was higher for patients with hepatopulmonary syndrome on the wait list. After liver transplantation, patients with a PaO2 <45 mmHg had a lower survival, but this only became significant after 2.6 years, and the median survival was 11.5 years. This suggests that patients with hepatopulmonary syndrome do benefit from transplantation.

Conservative oxygen therapy for critically ill patients: a meta-analysis of randomized controlled trials

ObjectiveConservative oxygen strategy is recommended in acute illness while its benefit in ICU patients remains controversial. Therefore, we sought to conduct a systematic review and meta-analysis to examine such oxygen strategies’ effect and safety in ICU patients.MethodsWe searched PubMed, Embase, and the Cochrane database from inception to Feb 15, 2021. Randomized controlled trials (RCTs) that compared a conservative oxygen strategy to a conventional strategy in critically ill patients were included. Results were expressed as mean difference (MD) and risk ratio (RR) with a 95% confidence interval (CI). The primary outcome was the longest follow-up mortality. Heterogeneity, sensitivity analysis, and publication bias were also investigated to test the robustness of the primary outcome.ResultsWe included seven trials with a total of 5265 patients. In general, the conventional group had significantly higher SpO2 or PaO2 than that in the conservative group. No statistically significant differences were found in the longest follow-up mortality (RR, 1.03; 95% CI, 0.97–1.10; I2=18%; P=0.34) between the two oxygen strategies when pooling studies enrolling subjects with various degrees of hypoxemia. Further sensitivity analysis showed that ICU patients with mild-to-moderate hypoxemia (PaO2/FiO2 >100 mmHg) had significantly lower mortality (RR, 1.24; 95% CI, 1.05–1.46; I2=0%; P=0.01) when receiving conservative oxygen therapy. These findings were also confirmed in other study periods. Additional, secondary outcomes of the duration of mechanical ventilation, the length of stay in the ICU and hospital, change in sequential organ failure assessment score, and adverse events were comparable between the two strategies.ConclusionsOur findings indicate that conservative oxygen therapy strategy did not improve the prognosis of the overall ICU patients. The subgroup of ICU patients with mild to moderate hypoxemia might obtain prognosis benefit from such a strategy without affecting other critical clinical results.

Severe COVID-19 and coagulopathy: A systematic review and meta-analysis

Coronavirus disease 2019 (COVID-19)-induced coagulopathy (CIC) has been widely reported in the literature. However, the spectrum of abnormalities associated with CIC has been highly variable. We conducted a systematic review of the literature (until 1 June 2020) to assess CIC and disease severity during the early COVID-19 pandemic. Primary outcomes were pooled mean differences in platelet count, D-dimer level, prothrombin time, activated partial thromboplastin time (aPTT) and fibrinogen level between non-severe and severe patients, stratified by degree of hypoxaemia or those who died. The risk factors for CIC were analysed. Random-effects meta-analyses and meta-regression were performed using R version 3.6.1, and certainty of evidence was rated using the Grading of Recommendation, Assessment, Development, and Evaluation approach. Of the included 5,243 adult COVID-19 patients, patients with severe COVID-19 had a significantly lower platelet count, and higher D-dimer level, prothrombin time and fibrinogen level than non-severe patients. Pooled mean differences in platelet count (-19.7×109/L, 95% confidence interval [CI] -31.7 to -7.6), D-dimer level (0.8μg/mL, 95% CI 0.5-1.1), prothrombin time (0.4 second, 95% CI 0.2-0.6) and fibrinogen level (0.6g/L, 95% CI 0.3-0.8) were significant between the groups. Platelet count and D-dimer level were significant predictors of disease severity on meta-regression analysis. Older men had higher risks of severe coagulopathic disease. Significant variability in CIC exists between non-severe and severe patients, with platelet count and D-dimer level correlating with disease severity. Routine monitoring of all coagulation parameters may help to assess CIC and decide on the appropriate management.

COVID-19 in Lung-Transplant Recipients: A Descriptive Study

PurposeTransplant recipients are more susceptible to infection, however the medical literature lacks sufficient data regarding COVID-19 post transplantation, especially in lung-transplant recipients. This population appears to be at higher risk for critical illness due to comorbidities and chronic immunosuppressive stateMethodsThis was a single-center, retrospective study of 7 lung-transplant recipients who were symptomatic and tested positive for COVID-19 between Feb 2020 and Oct 2020. Demographics, including single vs double lung transplantation, time from transplant were included. Laboratory data on admission, immunosuppressive regimen and adjustment during hospitalization, oxygen requirements and outcomes were also collectedResultsTo date, 7 out of 227 post-lung transplant patients followed at our center became symptomatic with COVID-19 infection. The average age was 60.5 years and 70% were female. All patients had double lung transplantation performed between Apr 2010 and Nov 2019. The average body mass index was 27.0 kg/m2. 85% required hospitalization, three had to be admitted to the intensive care unit, two required invasive mechanical ventilation. Two patients died (one due to acute kidney injury and refractory shock and one refused intubation). One patient on mechanical ventilation required VV ECMO 3 days after admission as a bridge to recovery. All patients were on standard triple immunosuppressive regimen [tacrolimus, mycophenolate, and prednisone]. Mycophenolate was stopped for all patients at the time of the infection, and those who required oxygen supplementation (n=5) received dexamethasone and convalescent plasma. Two of them were not eligible for Remdesivir. Elevated d-dimer (0.78 - 5.57 mg/L), LDH (253 - 985 U/L) and the degree of hypoxemia on admission correlated to worse outcomesConclusionCOVID-19 infection in lung transplant patients has a variable course. In our study, d-dimer, LDH and the degree of hypoxemia on admission had a linear correlation with unfavorable outcome, similar to what has been reported for non lung-transplant patients with COVID-19. Intubation and mechanical ventilation portend a poor prognosis. In our cohort reduction in net immunosuppression (stopping anti-metabolite) and supportive treatment was utilized. Prevention remains the best intervention for COVID-19

Comparison of the anesthetic effects between 5 mg/kg of alfaxalone and 10 mg/kg of propofol administered intravenously in cats.

To compare the anesthetic effects after intravenous administration of alfaxalone or propofol without premedication, either alfaxalone (5 mg/kg) or propofol (10 mg/kg) was administered intravenously over 120 sec in 6 cats. Each cat received the alternate treatment at least a 7-day interval. Anesthetic effects (tolerance of intubation, behavior changes and neurodepressive score) and physiological parameters were evaluated. Both treatments produced a rapid loss of consciousness, no apnea, and physiological parameters were maintained within clinically acceptable ranges apart from transient hypoxemia. The degree of hypoxemia was greater after the propofol treatment compared with the alfaxalone treatment. During the recovery period, more adverse events (ataxia, muscular tremors) were observed after the alfaxalone treatment compared with the propofol treatment.

Compliance Phenotypes in Early Acute Respiratory Distress Syndrome before the COVID-19 Pandemic.

Rationale: A novel model of phenotypes based on set thresholds of respiratory system compliance (Crs) was recently postulated in context of coronavirus disease (COVID-19) acute respiratory distress syndrome (ARDS). In particular, the dissociation between the degree of hypoxemia and Crs was characterized as a distinct ARDS phenotype.Objectives: To determine whether such Crs-based phenotypes existed among patients with ARDS before the COVID-19 pandemic and to closely examine the Crs–mortality relationship.Methods: We undertook a secondary analysis of patients with ARDS, who were invasively ventilated on controlled modes and enrolled in a large, multinational, epidemiological study. We assessed Crs, degree of hypoxemia, and associated Crs-based phenotypic patterns with their characteristics and outcomes.Measurements and Main Results: Among 1,117 patients with ARDS who met inclusion criteria, the median Crs was 30 (interquartile range, 23–40) ml/cm H2O. One hundred thirty-six (12%) patients had preserved Crs (≥50 ml/cm H2O; phenotype with low elastance [“phenotype L”]), and 827 (74%) patients had poor Crs (<40 ml/cm H2O; phenotype with high elastance [“phenotype H”]). Compared with those with phenotype L, patients with phenotype H were sicker and had more comorbidities and higher hospital mortality (32% vs. 45%; P < 0.05). A near complete dissociation between PaO2/FiO2 and Crs was observed. Of 136 patients with phenotype L, 58 (43%) had a PaO2/FiO2 < 150. In a multivariable-adjusted analysis, the Crs was independently associated with hospital mortality (adjusted odds ratio per ml/cm H2O increase, 0.988; 95% confidence interval, 0.979–0.996; P = 0.005).Conclusions: A wide range of Crs was observed in non–COVID-19 ARDS. Approximately one in eight patients had preserved Crs. PaO2/FiO2 and Crs were dissociated. Lower Crs was independently associated with higher mortality. The Crs–mortality relationship lacked a clear transition threshold.