New therapeutic strategy with extracorporeal membrane oxygenation for refractory hepatopulmonary syndrome after liver transplant: A case report

BACKGROUND

Due to the lack of published literature about treatment of refractory hepatopulmonary syndrome (HPS) after liver transplant (LT), this case adds information and experience on this issue along with a treatment with positive outcomes. HPS is a complication of end-stage liver disease, with a 10%-30% incidence in cirrhotic patients. LT can reverse the physiopathology of this process and restore normal oxygenation. However, in some cases, refractory hypoxemia persists, and extracorporeal membrane oxygenation (ECMO) can be used as a rescue therapy with good results.

CASE SUMMARY

A 59-year-old patient with alcohol-related liver cirrhosis and portal hypertension was included in the LT waiting list for HPS. He had good liver function (Model for End-Stage Liver Disease score 12, Child-Pugh class B7). He had pulmonary fibrosis and a mild restrictive respiratory pattern with a basal oxygen saturation of 82%. The macroaggregated albumin test result was > 30. Spirometry demon strated a forced expiratory volume in one second (FEV1) of 78%, forced vital capacity (FVC) of 74%, FEV1/FVC ratio of 81%, diffusion capacity for carbon monoxide of 42%, and carbon monoxide transfer coefficient of 57%. He required domiciliary oxygen at 2 L/min (16 h/d). The patient was admitted to the intensive care unit (ICU) and extubated in the first 24 h, needing high-flow therapy and non-invasive ventilation and inhaled nitric oxide afterwards. Reintubation was needed after 72 h. Due to the non-response to supportive therapies, installation of ECMO was decided with progressive recovery after 9 d. Extubation was possible on the tenth day, maintaining a high-flow nasal cannula and de-escalating to conventional oxygen therapy after 48 h. He was discharged from ICU on postoperative day (POD) 20 with a 90%-92% oxygen saturation. Steroid recycling was needed twice for acute rejection. The patient was discharged from hospital on POD 27 with no symptoms, with an 89%-90% oxygen saturation.

CONCLUSION

Due to the favorable results observed, ECMO could become the central axis of treatment of HPS and refractory hypoxemia after LT.

Characteristics and risk factors associated with mortality during the first cycle of prone secondary to ARDS due to SARS-CoV-2 pneumonia

OBJECTIVE

To analyze characteristics, changes in oxygenation, and pulmonary mechanics, in mechanically ventilated patients with ARDS due to SARS-CoV-2 treated with prone position and evaluate the response to this maneuver.

DESIGN

Cohort study including patients with PaO2/FiO2 <150mmHg requiring prone position over 18 months. We classified patients according to PaO2/FiO2 changes from basal to 24h after the first prone cycle as: 1) no increase 2) increase <25%, 3) 25%-50% increase 4) increase >50%.

SETTING

33-bed medical-surgical Intensive Care Unit (ICU) in Argentina.

PATIENTS

273 patients.

INTERVENTIONS

None.

MAIN VARIABLES OF INTEREST

Epidemiological characteristics, respiratory mechanics and oxygenation were compared between survivors and non-survivors. Independent factors associated with in-hospital mortality were identified.

RESULTS

Baseline PaO2/FiO2 was 116 [97-135]mmHg (115 [94-136] in survivors vs. 117 [98-134] in non-survivors; p=0.50). After prone positioning, 22 patients (8%) had similar PaO2/FiO2 values; 46(16%) increased PaO2/FiO2 ≤25%; 55 (21%) increased it 25%-50%; and 150 (55%), >50%. Mortality was 86%, 87%, 72% and 50% respectively (p<0.001). Baseline PaO2/FiO2, <100mmHg did not imply that patients were refractory to prone position. Factors independently associated with mortality were age, percentage increase in PaO2/FiO2 after 24h being in prone, and number of prone cycles.

CONCLUSIONS

Older patients unable to improve PaO2/FiO2 after 24h in prone position and who require >1 cycle might early receive additional treatments for refractory hypoxemia. After the first 24h in the prone position, a low percentage of PaO2/FiO2 increase over baseline, beyond the initial value, was independently associated with higher mortality.

Intraperitoneal oxygen microbubble therapy: A novel approach to enhance systemic oxygenation in a smoke inhalation model of acute hypoxic respiratory failure

Background

Patients suffering from severe acute respiratory distress syndrome (ARDS) face limited therapeutic options and alarmingly high mortality rates. Refractory hypoxemia, a hallmark of ARDS, often necessitates invasive and high-risk treatments. Oxygen microbubbles (OMB) present a promising approach for extrapulmonary oxygenation, potentially augmenting systemic oxygen levels without exposing patients to significant risks.

Methods

Rats with severe, acute hypoxemia secondary to wood smoke inhalation (SI) received intraperitoneal (IP) bolus injections of escalating weight-by-volume (BW/V) OMB doses or normal saline to determine optimal dosage and treatment efficacy. Subsequently, a 10 % BW/V OMB bolus or saline was administered to a group of SI rats and a control group of healthy rats (SHAM). Imaging, vital signs, and laboratory studies were compared at baseline, post-smoke inhalation, and post-treatment. Histological examination and lung tissue wet/dry weight ratios were assessed at study conclusion.

Results

Treatment with various OMB doses in SI-induced acute hypoxemia revealed that a 10 % BW/V OMB dose significantly augmented systemic oxygen levels while minimizing dose volume. The second set of studies demonstrated a significant increase in partial pressure of arterial oxygen (PaO2) and normalization of heart rate with OMB treatment in the SI group compared to saline treatment or control group treatment.

Conclusions

This study highlights the successful augmentation of systemic oxygenation following OMB treatment in a small animal model of severe hypoxemia. OMB therapy emerges as a novel and promising treatment modality with immense translational potential for oxygenation support in acute care settings.

Extracorporeal membrane oxygenation for paediatric refractory hypoxic respiratory failure caused by adenovirus in Shanghai: a case series

Background

To assess the outcome of extracorporeal membrane oxygenation (ECMO) for severe adenovirus (Adv) pneumonia with refractory hypoxic respiratory failure (RHRF) in paediatric patients.

Methods

A retrospective observational study was performed in a tertiary paediatric intensive care unit (PICU) in China. Patients with RHRF caused by Adv pneumonia who received ECMO support after mechanical ventilation failed to achieve adequate oxygenation between 2017 and 2020 were included. The outcome variables were the in-hospital survival rate and the effects of ECMO on the survival rate.

Results

In total, 18 children with RHRF received ECMO. The median age was 19 (9.5, 39.8) months, and the median ECMO duration was 196 (152, 309) h. The in-hospital survival rate was 72.2% (13/18). Thirteen patients (72.2%) required continuous renal replacement therapy (CRRT) due to fluid imbalance or acute kidney injury (AKI). At ECMO initiation, compared with survivors, nonsurvivors had a lower PaO₂/FiO₂ ratio [49 (34.5, 62) vs. 63 (56, 71); p = 0.04], higher oxygen index (OI) [41 (34.5, 62) vs. 30 (26.5, 35); p = 0.03], higher vasoactive inotropic score (VIS) [30 (16.3, 80) vs. 100 (60, 142.5); p = 0.04], longer duration from mechanical ventilation to ECMO support [8 (4, 14) vs. 4 (3, 5.5) h, p=0.02], and longer time from confirmed RHRF to ECMO initiation [9 (4.8, 13) vs. 5 (1.3, 5.5) h; p = 0.004]. Patients with PaO₂/FiO₂ <61 mmHg or an OI >43 and hypoxic respiratory failure for more than 9 days before the initiation of ECMO had worse outcomes.

Conclusions

ECMO seemed to be effective, as severe paediatric Adv pneumonia patients with RHRF had a cumulative survival rate of 72.2% in our study. Our study provides insight into ECMO rescue in children with severe Adv pneumonia.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-022-03197-2.

Prone position in intubated, mechanically ventilated patients with COVID-19: a multi-centric study of more than 1000 patients

Background

Limited data are available on the use of prone position in intubated, invasively ventilated patients with Coronavirus disease-19 (COVID-19). Aim of this study is to investigate the use and effect of prone position in this population during the first 2020 pandemic wave.

Methods

Retrospective, multicentre, national cohort study conducted between February 24 and June 14, 2020, in 24 Italian Intensive Care Units (ICU) on adult patients needing invasive mechanical ventilation for respiratory failure caused by COVID-19. Clinical data were collected on the day of ICU admission. Information regarding the use of prone position was collected daily. Follow-up for patient outcomes was performed on July 15, 2020. The respiratory effects of the first prone position were studied in a subset of 78 patients. Patients were classified as Oxygen Responders if the PaO₂/FiO₂ ratio increased ≥ 20 mmHg during prone position and as Carbon Dioxide Responders if the ventilatory ratio was reduced during prone position.

Results

Of 1057 included patients, mild, moderate and severe ARDS was present in 15, 50 and 35% of patients, respectively, and had a resulting mortality of 25, 33 and 41%. Prone position was applied in 61% of the patients. Patients placed prone had a more severe disease and died significantly more (45% vs. 33%, p < 0.001). Overall, prone position induced a significant increase in PaO₂/FiO₂ ratio, while no change in respiratory system compliance or ventilatory ratio was observed. Seventy-eight % of the subset of 78 patients were Oxygen Responders. Non-Responders had a more severe respiratory failure and died more often in the ICU (65% vs. 38%, p = 0.047). Forty-seven % of patients were defined as Carbon Dioxide Responders. These patients were older and had more comorbidities; however, no difference in terms of ICU mortality was observed (51% vs. 37%, p = 0.189 for Carbon Dioxide Responders and Non-Responders, respectively).

Conclusions

During the COVID-19 pandemic, prone position has been widely adopted to treat mechanically ventilated patients with respiratory failure. The majority of patients improved their oxygenation during prone position, most likely due to a better ventilation perfusion matching.

Trial registration: clinicaltrials.gov number: NCT04388670

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-021-03552-2.

The use of ECMO in ICU. Recommendations of the Spanish Society of Critical Care Medicine and Coronary Units

The use of extracorporeal membrane oxygenation systems has increased significantly in recent years; given this reality, the Spanish Society of Critical Intensive Care Medicine and Coronary Units (SEMICYUC) has decided to draw up a series of recommendations that serve as a framework for the use of this technique in intensive care units. The three most frequent areas of extracorporeal membrane oxygenation systems use in our setting are: as a cardiocirculatory support, as a respiratory support and for the maintenance of the abdominal organs in donors. The SEMICYUC appointed a series of experts belonging to the three working groups involved (Cardiological Intensive Care and CPR, Acute Respiratory Failure and Transplant work group) that, after reviewing the existing literature until March 2018, developed a series of recommendations. These recommendations were posted on the SEMICYUC website to receive suggestions from the intensivists and finally approved by the Scientific Committee of the Society. The recommendations, based on current knowledge, are about which patients may be candidates for the technique, when to start it and the necessary infrastructure conditions of the hospital centers or, the conditions for transfer to centers with experience. Although from a physiopathological point of view, there are clear arguments for the use of extracorporeal membrane oxygenation systems, the current scientific evidence is weak, so studies are needed that define more precisely which patients benefit most from the technique and when they should start.

Salvage therapies for refractory hypoxemia in ARDS

Acute Respiratory Distress Syndrome (ARDS) is a condition of varied etiology characterized by the acute onset (within 1 week of the inciting event) of hypoxemia, reduced lung compliance, diffuse lung inflammation and bilateral opacities on chest imaging attributable to noncardiogenic (increased permeability) pulmonary edema. Although multi-organ failure is the most common cause of death in ARDS, an estimated 10-15% of the deaths in ARDS are caused due to refractory hypoxemia, i.e.- hypoxemia despite lung protective conventional ventilator modes. In these cases, clinicians may resort to other measures with less robust evidence -referred to as "salvage therapies". These include proning, 48 h of paralysis early in the course of ARDS, various recruitment maneuvers, unconventional ventilator modes, inhaled pulmonary vasodilators, and Extracorporeal membrane oxygenation (ECMO). All the salvage therapies described have been associated with improved oxygenation, but with the exception of proning and 48 h of paralysis early in the course of ARDS, none of them have a proven mortality benefit. Based on the current evidence, no salvage therapy has been shown to be superior to the others and each of them is associated with its own risks and benefits. Hence, the order of application of these therapies varies in different institutions and should be applied following a risk-benefit analysis specific to the patient and local experience. This review explores the rationale, evidence, advantages and risks behind each of these strategies.

Associations between ventilator settings during extracorporeal membrane oxygenation for refractory hypoxemia and outcome in patients with acute respiratory distress syndrome: a pooled individual patient data analysis : Mechanical ventilation during ECMO

Purpose

Extracorporeal membrane oxygenation (ECMO) is a rescue therapy for patients with acute respiratory distress syndrome (ARDS). The aim of this study was to evaluate associations between ventilatory settings during ECMO for refractory hypoxemia and outcome in ARDS patients.

Methods

In this individual patient data meta-analysis of observational studies in adult ARDS patients receiving ECMO for refractory hypoxemia, a time-dependent frailty model was used to determine which ventilator settings in the first 3 days of ECMO had an independent association with in-hospital mortality.

Results

Nine studies including 545 patients were included. Initiation of ECMO was accompanied by significant decreases in tidal volume size, positive end-expiratory pressure (PEEP), plateau pressure, and driving pressure (plateau pressure − PEEP) levels, and respiratory rate and minute ventilation, and resulted in higher PaO₂/FiO₂, higher arterial pH and lower PaCO₂ levels. Higher age, male gender and lower body mass index were independently associated with mortality. Driving pressure was the only ventilatory parameter during ECMO that showed an independent association with in-hospital mortality [adjusted HR, 1.06 (95 % CI, 1.03–1.10)].

Conclusion

In this series of ARDS patients receiving ECMO for refractory hypoxemia, driving pressure during ECMO was the only ventilator setting that showed an independent association with in-hospital mortality.

Electronic supplementary material

The online version of this article (doi:10.1007/s00134-016-4507-0) contains supplementary material, which is available to authorized users.

The standard of care of patients with ARDS: ventilatory settings and rescue therapies for refractory hypoxemia. Intensive Care Med. 2016;42:699-711. [PMID: 27040102 PMCID: PMC4828494 DOI: 10.1007/s00134-016-4325-4]

Purpose

Severe ARDS is often associated with refractory hypoxemia, and early identification and treatment of hypoxemia is mandatory. For the management of severe ARDS ventilator settings, positioning therapy, infection control, and supportive measures are essential to improve survival.

Methods and results

A precise definition of life-threating hypoxemia is not identified. Typical clinical determinations are: arterial partial pressure of oxygen < 60 mmHg and/or arterial oxygenation < 88 % and/or the ratio of PaO₂/FIO₂ < 100. For mechanical ventilation specific settings are recommended: limitation of tidal volume (6 ml/kg predicted body weight), adequate high PEEP (>12 cmH₂O), a recruitment manoeuvre in special situations, and a ‘balanced’ respiratory rate (20-30/min). Individual bedside methods to guide PEEP/recruitment (e.g., transpulmonary pressure) are not (yet) available. Prone positioning [early (≤ 48 hrs after onset of severe ARDS) and prolonged (repetition of 16-hr-sessions)] improves survival. An advanced infection management/control includes early diagnosis of bacterial, atypical, viral and fungal specimen (blood culture, bronchoalveolar lavage), and of infection sources by CT scan, followed by administration of broad-spectrum anti-infectives. Neuromuscular blockage (Cisatracurium ≤ 48 hrs after onset of ARDS), as well as an adequate sedation strategy (score guided) is an important supportive therapy. A negative fluid balance is associated with improved lung function and the use of hemofiltration might be indicated for specific indications.

Conclusions

A specific standard of care is required for the management of severe ARDS with refractory hypoxemia.

[Platypnea-orthodeoxia syndrome: a rare cause of severe hypoxemia]

INTRODUCTION

The platypnea-orthodeoxia syndrome (PO) includes: (i) a dyspnea increasing with orthostatism and decreasing in supine position, (ii) wide positional range in arterial oxygen saturation with tachycardia, (iii) and hypoxemia refractory to oxygen therapy. This syndrome is usually related to a cardiac right-left shunt, and rarely to a pulmonary shunt.

OBSERVATION

We report a case of a patient presenting with a post-lung infection dyspnea associated with severe hypoxemia and shunt effect at blood gas. Contrast-enhanced CT-scan showed no pulmonary embolism. PO syndrome was suspected given the transcutaneous blood oxygen saturation variation from 90% in supine position to 60% in standing position, tachycardia, and absence of response to the intensive oxygen therapy.

CONCLUSION

This syndrome should be known by physicians as a possible differential diagnose for refractory dyspnea to oxygen since effective treatment is available.

To ventilate, oscillate, or cannulate?

Ventilatory management of acute respiratory distress syndrome has evolved significantly in the last few decades. The aims have shifted from optimal gas transfer without concern for iatrogenic risks to adequate gas transfer while minimizing lung injury. This change in focus, along with improved ventilator and multiorgan system management, has resulted in a significant improvement in patient outcomes. Despite this, a number of patients develop hypoxemic respiratory failure refractory to lung-protective ventilation (LPV). The intensivist then faces the dilemma of either persisting with LPV using adjuncts (neuromuscular blocking agents, prone positioning, recruitment maneuvers, inhaled nitric oxide, inhaled prostacyclin, steroids, and surfactant) or making a transition to rescue therapies such as high-frequency oscillatory ventilation (HFOV) and/or extracorporeal membrane oxygenation (ECMO) when both these modalities are at their disposal. The lack of quality evidence and potential harm reported in recent studies question the use of HFOV as a routine rescue option. Based on current literature, the role for venovenous (VV) ECMO is probably sequential as a salvage therapy to ensure ultraprotective ventilation in selected young patients with potentially reversible respiratory failure who fail LPV despite neuromuscular paralysis and prone ventilation. Given the risk profile and the economic impact, future research should identify the patients who benefit most from VV ECMO. These choices may be further influenced by the emerging novel extracorporeal carbon dioxide removal devices that can compliment LPV. Given the heterogeneity of acute respiratory distress syndrome, each of these modalities may play a role in an individual patient. Future studies comparing LPV, HFOV, and VV ECMO should not only focus on defining the patients who benefit most from each of these therapies but also consider long-term functional outcomes.