Blood transfusion strategies and ECMO during the COVID-19 pandemic - Authors' reply

Haematological Trends and Transfusion during Adult Extracorporeal Membrane Oxygenation: A Single Centre Study

The temporal trends in haematological parameters and their associations with blood product transfusion requirements in patients supported with extracorporeal membrane oxygenation (ECMO) are poorly understood. We performed a retrospective data analysis to better understand the behaviour of haematological and coagulation parameters and their associations with transfusion requirements during ECMO.

METHODS

Patient demographics, haematological and coagulation parameters, plasma haemoglobin and fibrinogen concentrations, platelet count, the international normalised ratio (INR), the activated partial thromboplastin time (APTT), and blood product transfusion data from 138 patients who received ECMO in a single high-volume centre were analysed.

RESULTS

Ninety-two patients received venoarterial (VA) ECMO and 46 patients received venovenous (VV) ECMO. The median (IQR) duration of VA, and VV ECMO was 8 (5-13) days and 13 (8-23) days, respectively. There were significant reductions in haemoglobin, the platelet count, and the fibrinogen concentration upon initiation of ECMO. On average, over time, patients on VV ECMO had platelet counts 44 × 109/L higher than those on VA ECMO (p ≤ 0.001). Fibrinogen and APTT did not vary significantly based on the mode of ECMO (p = 0.55 and p = 0.072, respectively). A platelet count < 50 × 109/L or a fibrinogen level < 1.8 g/L was associated with 50% chance of PRBC transfusion, regardless of the ECMO type, and packed red blood cell (PRBC) transfusion was more common with VA ECMO. APTT was predictive of the transfusion requirement, and the decrement in APTT was discriminatory between VVECMO survivors and nonsurvivors.

CONCLUSION

ECMO support is associated with reductions in haemoglobin, platelet count, and fibrinogen. Patients supported with VA ECMO are more likely to receive a PRBC transfusion compared to those on VV ECMO. Thrombocytopaenia, hypofibrinogenaemia, and anticoagulation effect the likelihood of requiring PRBC transfusion. Further research is needed to define optimal blood management during ECMO, including appropriate transfusion triggers and the anticoagulation intensity.

The Use of ECMO for COVID-19: Lessons Learned

The coronavirus disease 2019 (COVID-19) pandemic has seen an increase in global cases of severe acute respiratory distress syndrome (ARDS), with a concomitant increased demand for extracorporeal membrane oxygenation (ECMO). Outcomes of patients with severe ARDS due to COVID-19 infection receiving ECMO support are evolving. The need for surge capacity, practical and ethical limitations on implementing ECMO, and the prolonged duration of ECMO support in patients with COVID-19-related ARDS has revealed limitations in organization and resource utilization. Coordination of efforts at multiple levels, from research to implementation, resulted in numerous innovations in the delivery of ECMO.

The impact of reduction in intensity of mechanical ventilation upon venovenous ECMO initiation on radiographically assessed lung edema scores: A retrospective observational study

Background

Patients with severe acute respiratory distress syndrome (ARDS) typically receive ultra-protective ventilation after extracorporeal membrane oxygenation (ECMO) is initiated. While the benefit of ECMO appears to derive from supporting “lung rest”, reductions in the intensity of mechanical ventilation, principally tidal volume limitation, may manifest radiologically. This study evaluated the relative changes in radiographic assessment of lung edema (RALE) score upon venovenous ECMO initiation in patients with severe ARDS.

Methods

Digital chest x-rays (CXR) performed at baseline immediately before initiation of ECMO, and at intervals post (median 1.1, 2.1, and 9.6 days) were reviewed in 39 Adult ARDS patients. One hundred fifty-six digital images were scored by two independent, blinded radiologists according to the RALE (Radiographic Assessment of Lung Edema) scoring criteria. Ventilatory data, ECMO parameters and fluid balance were recorded at corresponding time points. Multivariable analysis was performed analyzing the change in RALE score over time relative to baseline.

Results

The RALE score demonstrated excellent inter-rater agreement in this novel application in an ECMO cohort. Mean RALE scores increased from 28 (22–37) at baseline to 35 (26–42) (p < 0.001) on D1 of ECMO; increasing RALE was associated with higher baseline APACHE III scores [ß value +0.19 (0.08, 0.30) p = 0.001], and greater reductions in tidal volume [ß value −2.08 (−3.07, −1.10) p < 0.001] after ECMO initiation. Duration of mechanical ventilation, and ECMO support did not differ between survivors and non-survivors.

Conclusions

The magnitude of reductions in delivered tidal volumes correlated with increasing RALE scores (radiographic worsening) in ARDS patients receiving ECMO. Implications for patient centered outcomes remain unclear. There is a need to define appropriate ventilator settings on venovenous ECMO, counterbalancing the risks vs. benefits of optimal “lung rest” against potential atelectrauma.

Extracorporeal membrane oxygenation and rehabilitation in patients with COVID-19: A scoping review

Background and purpose

The coronavirus diseases 2019 (COVID‐19) pandemic posed severe difficulties in managing critically ill patients in hospital care settings. Extracorporeal membrane oxygenation (ECMO) support has been proven to be lifesaving support during the SARS‐CoV‐2 outbreak. The purpose of this review was to describe the rehabilitative treatments provided to patients undergoing ECMO support during the COVID‐19 pandemic.

Methods

We searched PubMed and Scopus for English‐language studies published from the databases’ inception until June 30, 2021. We excluded editorials, letters to the editor, and studies that did not describe rehabilitative procedures during ECMO support. We also excluded those articles not written in English.

Results

A total of 50 articles were identified. We ultimately included nine studies, seven of which were case reports. Only two studies had more than one patient; an observational design analyzing the clinical course of 19 patients and a case series of three patients. Extracorporeal support duration varied from 9 to 49 days, and the primary indication was acute respiratory distress syndrome COVID‐19‐related. Rehabilitative treatment mainly consisted of in‐bed mobilization, postural transfers (including sitting), and respiratory exercises. After hospital discharge, patients were referred to rehabilitation facilities. Physiotherapeutic interventions provided during ECMO support and after its discontinuation were feasible and safe.

Conclusion

The physiotherapeutic treatment of patients undergoing ECMO support includes several components and must be provided in a multidisciplinary context. The optimal approach depends on the patient’s status, including sedation, level of consciousness, ECMO configuration, types of cannulas, and cannulation site.

Hospital transfusion service operations during the SARS-CoV-2 pandemic: Lessons learned from the AABB hospital survey in preparation for the next infectious disease outbreak

Background

The SARS‐CoV‐2 pandemic disrupted hospital operations, affected the blood supply, and challenged the health care system to develop new therapeutic options, including convalescent plasma (CCP). The aim of this study is to describe and analyze blood supply fluctuations and the use of convalescent plasma in 2020.

Methods

AABB distributed a weekly and biweekly questionnaire through email to hospital‐based members (HBM).

Results

The survey was sent to 887 HBM with 479 unique respondents, most of the hospitals served pediatric and adult patients, and all states of the country participated, except Idaho and Vermont. Fifty four percent of HBM reported increased wastage in the early phase of the pandemic (May), which decreased to 4% by the end of June and throughout the rest of the year. The majority of HBM reported receiving alerts from their blood suppliers reporting blood shortages throughout the year. During March and April, only 12% of HBM were performing elective surgical procedures. The top reasons to delay procedures were: bed availability (28%); COVID‐19 caseload (23%; and blood availability (19%). By mid‐April, 42% HBM had transfused CCP and reported >24 h delay in getting the units; the vast majority obtained CCP using the Expanded Access Protocol, and later, the Emergency Use Authorization. HBM consistently prioritized the most severe patients to receive CCP, but the proportion of severely ill recipients fell from 52% to 37% between May and October, with an increase from 5% to 21% of HBM providing CCP transfusion early in the course of the disease.

Discussion

Blood utilization and availability fluctuated during the pandemic. The fluctuations appeared to be related to the number of COVID‐19 in the community. The use and regulatory landscape of CCP rapidly evolved over the first 8 months of the pandemic.

COVID-19 pandemic and transfusion medicine: the worldwide challenge and its implications

COVID-19 pandemic has imposed worldwide challenge and has significantly affected transfusion medicine. Shortage in blood products along with concerns regarding the safety of blood products have emerged. Measures to overcome these challenges have been implemented in order to decrease the demand on blood products and to encourage blood donations while taking full precautions to minimize risk of COVID-19 transmission mainly at blood banks and medical centers. Several countries have been successful in facing these new challenges. In addition, the role of plasma therapy in the treatment of COVID-19 patients, especially in severe cases, has been proposed and current studies are being conducted to determine its efficacy. Other therapeutic options are currently being explored. So far, the use of convalescent plasma is considered a promising rescue treatment to be looked at.