Anti-Xa Assay Monitoring Improves the Precision of Anticoagulation in Venovenous Extracorporeal Membrane Oxygenation

Unfractionated heparin (UFH) is the most used anticoagulant in patients receiving veno-venous extracorporeal membrane oxygenation (VV-ECMO). Its therapeutic levels are monitored using activated partial thromboplastin time ratio (aPTTr) or antifactor Xa (anti-Xa) assay. This was a retrospective, single-center, cohort study where all adult patients with viral etiology respiratory failure requiring VV-ECMO from January 2, 2015 to January 31, 2022 were included. Anticoagulation was monitored using aPTTr (until November 1, 2019) or anti-Xa assay (after November 1, 2019). We compared the accuracy and precision of anticoagulation monitoring tests using time in therapeutic range (TTR) and variance growth rate (VGR), respectively, and their impact on bleeding and thrombotic events (BTEs). A total of 254 patients, 74 in aPTTr and 180 in anti-Xa monitoring groups, were included with a total of 4,992 ECMO-person days. Accuracy was comparable: mean TTR of 47% in aPTTr and 51% in anti-Xa groups ( p = 0.28). Antifactor Xa monitoring group demonstrated improved precision with a lower variance (median VGR 0.21 vs. 1.61 in aPTTr, p < 0.05). Secondary outcome of less heparin prescription changes (adjusted rate ratio [RR] = 1.01, p = 0.01), fewer blood transfusions (adjusted RR = 0.78, p < 0.05), and ECMO circuit changes (adjusted RR = 0.68, p < 0.05) were seen with anti-Xa monitoring.

The History of Extracorporeal Membrane Oxygenation and the Development of Extracorporeal Membrane Oxygenation Anticoagulation

Extracorporeal membrane oxygenation (ECMO) was first started for humans in early 1970s by Robert Bartlett. Since its inception, there have been numerous challenges with extracorporeal circulation, such as coagulation and platelet activation, followed by consumption of coagulation factors and platelets, and biocompatibility of tubing, pump, and oxygenator. Unfractionated heparin (heparin hereafter) has historically been the defacto anticoagulant until recently. Also, coagulation monitoring was mainly based on bedside activated clotting time and activated partial thromboplastin time. In the past 50 years, the technology of ECMO has advanced tremendously, and thus, the survival rate has improved significantly. The indication for ECMO has also expanded. Among these are clinical conditions such as postcardiopulmonary bypass, sepsis, ECMO cardiopulmonary resuscitation, and even severe coronavirus disease 2019 (COVID-19). Not surprisingly, the number of ECMO cases has increased according to the Extracorporeal Life Support Organization Registry and prolonged ECMO support has become more prevalent. It is not uncommon for patients with COVID-19 to be on ECMO support for more than 1 year until recovery or lung transplant. With that being said, complications of bleeding, thrombosis, clot formation in the circuit, and intravascular hemolysis still remain and continue to be major challenges. Here, several clinical ECMO experts, including the "Father of ECMO"-Dr. Robert Bartlett, describe the history and advances of ECMO.

Consumptive coagulopathy in the ICU

A consumptive coagulopathy describes a situation where there is a loss of hemostatic factors, which leads to an increased risk of bleeding. Some recent studies have used the term interchangeably with disseminated intravascular coagulation (DIC), but we have reverted to the older definition, which covers a broader range of issues where there is loss of hemostatic factors due to multiple causes, which includes systemic activation of coagulation as seen in DIC. Therefore, the term consumptive coagulopathy covers conditions from the hemostatic effects of major hemorrhage to the use of extracorporeal circuits to true DIC. We review the current understanding of the pathophysiology, diagnosis, and management of common consumptive coagulopathy in critical care patients, focusing on recent advances and controversies. Particular emphasis is given to DIC because it is a common and often life-threatening condition in critical care patients and is characterized by the simultaneous occurrence of widespread microvascular thrombosis and bleeding. Second, we focus on the effect of modern medical technology, such as extracorporeal membrane oxygenation, on hemostasis.

Clinical impact of screening computed tomography in extracorporeal membrane oxygenation: a retrospective cohort study

BACKGROUND

Data on the prevalence and clinical impact of extrapulmonary findings at screening computed tomography (CT) on initiation of veno-venous extracorporeal membrane oxygenation (V-V ECMO) are limited. We aimed to identify the prevalence of extrapulmonary findings on screening CT following V-V ECMO initiation. We hypothesized that extrapulmonary findings would influence clinical management and outcome.

METHODS

Retrospective analysis (2011-2021) of admission screening CT including head, abdomen and pelvis with contrast of consecutive patients on initiation of V-V ECMO. CT findings identified by the attending consultant radiologist were extracted. Demographics, admission physiological and laboratory data, clinical decision-making following CT and ECMO ICU mortality were recorded from the electronic medical record. We used multivariable logistic regression and Kaplan-Meier curves to evaluate associations between extrapulmonary findings and ECMO ICU mortality.

RESULTS

Of the 833 patients receiving V-V ECMO, 761 underwent routine admission CT (91.4%). ECMO ICU length of stay was 19 days (IQR 12-23); ICU mortality at the ECMO centre was 18.9%. An incidental extrapulmonary finding was reported in 227 patients (29.8%), leading to an invasive procedure in 12/227 cases (5.3%) and a change in medical management (mainly in anticoagulation strategy) in 119/227 (52.4%). Extrapulmonary findings associated with mortality were intracranial haemorrhage (OR 2.34 (95% CI 1.31-4.12), cerebral infarction (OR 3.59 (95% CI 1.26-9.86) and colitis (OR 2.80 (95% CI 1.35-5.67).

CONCLUSIONS

Screening CT frequently identifies extrapulmonary findings of clinical significance. Newly detected intracranial haemorrhage, cerebral infarction and colitis were associated with increased ICU mortality.

Prevalence and Indications for Oxygenator Circuit Replacement in Patients Receiving Venovenous Extracorporeal Membrane Oxygenation

In this retrospective observational cohort study, we aimed to describe the rate of extracorporeal membrane oxygenation (ECMO) circuit change, the associated risk factors and its relationship with patient characteristics and outcome in patients receiving venovenous (VV) ECMO at our center between January 2015 and November 2017. Twenty-seven percent of the patients receiving VV ECMO (n = 224) had at least one circuit change, which was associated with lower ICU survival (68% vs 82% p=0.032) and longer ICU stay (30 vs . 17 days p < 0.001). Circuit duration was similar when stratified by gender, clinical severity, or prior circuit change. Hematological abnormalities and increased transmembrane lung pressure (TMLP) were the most frequent indication for circuit change. The change in transmembrane lung resistance (Δ TMLR) gave better prediction of circuit change than TMLP, TMLR, or ΔTMLP. Low postoxygenator PO 2 was indicated as a reason for one-third of the circuit changes. However, the ECMO oxygen transfer was significantly higher in cases of circuit change with documented "low postoxygenator PO 2 " than those without (244 ± 62 vs. 200 ± 57 ml/min; p = 0.009). The results suggest that circuit change in VV ECMO is associated with worse outcomes, that the Δ TMLR is a better predictor of circuit change than TMLP, and that the postoxygenator PO 2 is an unreliable proxy for the oxygenator function.

Relationship between D-dimers and dead-space on disease severity and mortality in COVID-19 acute respiratory distress syndrome: A retrospective observational cohort study

BACKGROUND

Despite its diagnostic and prognostic importance, physiologic dead space fraction is not included in the current ARDS definition or severity classification. ARDS caused by COVID-19 (C-ARDS) is characterized by increased physiologic dead space fraction and hypoxemia. Our aim was to investigate the relationship between dead space indices, markers of inflammation, immunothrombosis, severity and intensive care unit (ICU) mortality.

RESULTS

Retrospective data including demographics, gas exchange, ventilatory parameters, and respiratory mechanics in the first 24 h of invasive ventilation. Plasma concentrations of D-dimers and ferritin were not significantly different across C-ARDS severity categories. Weak relationships were found between D-dimers and VR (r = 0.07, p = 0.13), P_ETCO₂/PaCO₂ (r = -0.1, p = 0.02), or estimated dead space fraction (r = 0.019, p = 0.68). Age, PaO₂/FiO₂, pH, P_ETCO₂/PaCO₂ and ferritin, were independently associated with ICU mortality. We found no association between D-dimers or ferritin and any dead-space indices adjusting for PaO₂/FiO₂, days of ventilation, tidal volume, and respiratory system compliance.

CONCLUSIONS

We report no association between dead space and inflammatory markers in mechanically ventilated patients with C-ARDS. Our results support theories suggesting that multiple mechanisms, in addition to immunothrombosis, play a role in the pathophysiology of respiratory failure and degree of dead space in C-ARDS.

Steroid exposure and outcome in COVID-19 pneumonia

Background

Corticosteroids are used to treat COVID-19 pneumonia. However, the optimal dose is unclear. This study describes the association between corticosteroid exposure with disease severity and outcome in COVID-19 pneumonia.

Methods

This is a single-centre retrospective, observational study including adult ICU patients who received systemic corticosteroids for COVID-19 pneumonia between March 2020 and March 2021. We recorded patient characteristics, disease severity, total steroid exposure, respiratory support and gas exchange data, and 90-day mortality.

Results

We included 362 patients. We allocated patients to groups with increasing disease severity according to the highest level of respiratory support that they received: high-flow nasal oxygen or continuous positive airway pressure (HFNO/CPAP) in 12.7%, invasive mechanical ventilation (IMV) in 61.6%, and extracorporeal membrane oxygenation (ECMO) in 25.7%. For these three groups, the median (inter-quartile range [IQR]) age was 61 (54-71) vs 58 (50-66) vs 46 (38-53) yr, respectively (P<0.001); median (IQR) APACHE (Acute Physiology and Chronic Health Evaluation) II scores were 12 (9-15) vs 14 (12-18) vs 15 (12-17), respectively (P=0.006); the median (IQR) lowest P a O 2 /FiO₂ ratio was 15.1 (11.8-21.7) vs 15.1 (10.7-22.2) vs 9.5 (7.9-10.9) kPa, respectively (P<0.001). Ninety-day mortality was 9% vs 27% vs 37% (P=0.002). Median (IQR) dexamethasone-equivalent exposure was 37 (24-62) vs 174 (86-504) vs 535 (257-1213) mg (P<0.001). 'Pulsed' steroids were administered to 26% of the IMV group and 48% of the ECMO group. Patients with higher disease severity who received pulse steroids had a higher 90-day mortality.

Conclusions

Corticosteroid exposure increased with the severity of COVID-19 pneumonia. Pulsed dose steroids were used more frequently in patients receiving greater respiratory support. Future studies should address patient selection and outcomes associated with pulsed dose steroids in patients with severe and deteriorating COVID-19 pneumonia.

Survival benefit of extracorporeal membrane oxygenation in severe COVID-19: a multi-centre-matched cohort study

Purpose

Extracorporeal membrane oxygenation (ECMO) has become an established therapy for severe respiratory failure in coronavirus disease 2019 (COVID-19). The added benefit of receiving ECMO in COVID-19 remains uncertain. The aim of this study is to analyse the impact of receiving ECMO at specialist centres on hospital mortality.

Methods

A multi-centre retrospective study was conducted in COVID-19 patients from 111 hospitals, referred to two specialist ECMO centres in the United Kingdom (UK) (March 2020 to February 2021). Detailed covariate data were contemporaneously curated from electronic referral systems. We analysed added benefit of ECMO treatment in specialist centres using propensity score matching techniques.

Results

1363 patients, 243 receiving ECMO, were analysed. The best matching technique generated 209 matches, with a marginal odds ratio (OR) for mortality of 0.44 (95% CI 0.29–0.68, p < 0.001) and absolute mortality reduction of 18.2% (44% vs 25.8%, p < 0.001) for treatment with ECMO in a specialist centre.

Conclusion

We found ECMO provided at specialist centres conferred significant survival benefit. Where resources and specialism allow, ECMO should be widely offered.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00134-022-06645-w.

A survey on the practices and capabilities in the management of respiratory failure in South East England

Introduction

The variability of acute respiratory distress syndrome management may affect the referral practice to severe respiratory failure centres. We described the management of acute respiratory distress syndrome in our catchment area.

Methods

An electronic survey was administered to 42 intensive care units in South-East England.

Results

Response rate was 71.4%. High-flow nasal oxygen and non-invasive ventilation were used 'often' in moderate-acute respiratory distress syndrome by 46.7% and 60%. During invasive ventilation, 90% preferred pressure control, targeting tidal volumes of 6-8 ml/kg (53.3%) or 4-6 ml/kg (46.7%). Positive end-expiratory pressure was selected by positive end-expiratory pressure/inspiratory fraction of oxygen tables (50%) or decremental positive end-expiratory pressure trials (20%). Neuro-muscular blockers were widely used, although routinely by only 3.3%. High-frequency oscillatory ventilation (10%) and inhaled nitric oxide (13.3%) were rarely used. None used oesophageal manometry. Recruitment manoeuvres were used 'often' by 26.7%. Equipment (90%) and protocols (80%) for prone position were common, with sessions mostly lasting 12-18 h.

Conclusions

Although variable, practice well reflected the available evidence. Proning was widely practiced with good availability of educational resources and protocolised care.

Impact and Determinants of High-Sensitivity Cardiac Troponin-T Concentration in Patients With COVID-19 Admitted to Critical Care

Cardiac Troponin (hs-TnT) elevation has been reported in unselected patients hospitalized with COVID-19 however the mechanism and relationship with mortality remain unclear. Consecutive patients admitted to a high-volume intensive care unit (ICU) in London with severe COVID-19 pneumonitis were included if hs-TnT concentration at admission was known. Kaplan-Meier survival analysis performed, with cohorts classified a priori by multiples of the upper limit of normal (ULN). 277 patients were admitted during a 7-week period in 2020; 176 were included (90% received invasive ventilation). hs-TnT at admission was 16.5 (9.0 to 49.3) ng/L, 56% had concentrations >ULN. 56 patients (31.8%) died during the index admission. Admission hs-TnT level was lower in survivors (12.0 (8.0-27.8) vs 28.5 (14.0 to 81.0) ng/L, p = 0.001). Univariate predictors of mortality were age, APACHE-II Score and admission hs-TnT (HR 1.73, p = 0.007). By multivariate regression, only age (HR 1.33, CI: 1.16.to 1.51, p < 0.01) and admission hs-TnT (HR 1.94, CI: 1.22 to 3.10, p = 0.006) remained predictive. Survival was significantly lower when admission hs-TnT was >ULN (log-rank p-value<0.001). Peak hs-TnT was higher in those who died but was not predictive of death after adjustment for other factors. In conclusion, in critically ill patients with COVID-19 pneumonitis, the hs-TnT level at admission is a powerful independent predictor of the likelihood of surviving to discharge from ICU. In most cases, hs-TnT elevation does not represent major myocardial injury but acts as a sensitive integrated biomarker of global stress. Whether stratification based on admission Troponin level could be used to guide prognostication and management warrants further evaluation.

Veno-venous extracorporeal membrane oxygenation in coronavirus disease 2019: a case series

Background

The use of veno-venous extracorporeal membrane oxygenation (VV-ECMO) in severe hypoxaemic respiratory failure from coronavirus disease 2019 (COVID-19) has been described, but reported utilisation and outcomes are variable, and detailed information on patient characteristics is lacking. We aim to report clinical characteristics, management and outcomes of COVID-19 patients requiring VV-ECMO, admitted over 2 months to a high-volume centre in the UK.

Methods

Patient information, including baseline characteristics and clinical parameters, was collected retrospectively from electronic health records for COVID-19 VV-ECMO admissions between 3 March and 2 May 2020. Clinical management is described. Data are reported for survivors and nonsurvivors.

Results

We describe 43 consecutive patients with COVID-19 who received VV-ECMO. Median age was 46 years (interquartile range 35.5–52.5) and 76.7% were male. Median time from symptom onset to VV-ECMO was 14 days (interquartile range 11–17.5). All patients underwent computed tomography imaging, revealing extensive pulmonary consolidation in 95.3%, and pulmonary embolus in 27.9%. Overall, 79.1% received immunomodulation with methylprednisolone for persistent maladaptive hyperinflammatory state. Vasopressors were used in 86%, and 44.2% received renal replacement therapy. Median duration on VV-ECMO was 13 days (interquartile range 8–20). 14 patients died (32.6%) and 29 survived (67.4%) to hospital discharge. Nonsurvivors had significantly higher d-dimer (38.2 versus 9.5 mg·L⁻¹, fibrinogen equivalent units; p=0.035) and creatinine (169 versus 73 μmol·L⁻¹; p=0.022) at commencement of VV-ECMO.

Conclusions

Our data support the use of VV-ECMO in selected COVID-19 patients. The cohort was characterised by high degree of alveolar consolidation, systemic inflammation and intravascular thrombosis.

VV-ECMO, when offered to #COVID19 patients in refractory respiratory failure, can be associated with favourable outcomes. This is a detailed case series of 43 COVID-19 patients requiring VV-ECMO from a UK centre. 67.4% survived to hospital discharge.https://bit.ly/3ko9Ucu

Blood component use in critical care in patients with COVID-19 infection: a single-centre experience

There has been a significant surge in admissions to critical care during the coronavirus disease 2019 (COVID‐19) pandemic. At present, the demands on blood components have not been described. We reviewed their use during the first 6 weeks of the outbreak from 3 March 2020 in a tertiary‐level critical care department providing venovenous extracorporeal membrane oxygenation (vv‐ECMO). A total of 265 patients were reviewed, with 235 not requiring ECMO and 30 requiring vv‐ECMO. In total, 50 patients required blood components during their critical care admission. Red cell concentrates were the most frequently transfused component in COVID‐19‐infected patients with higher rates of use during vv‐ECMO. The use of fresh frozen plasma, cryoprecipitate and platelet transfusions was low in a period prior to the use of convalescent plasma.

Use of Intravenous Immunoglobulins in Patients with Suspected Toxin-Mediated Shock Requiring Extracorporeal Membrane Oxygenation

BACKGROUND

Toxin-producing, gram-positive bacteria can lead to severe and refractory septic shock with high attributable mortality. Adjunctive therapies such as intravenous immunoglobulins (IVIG) have been proposed for these patients. However, at presentation the presence of a toxin-producing organism is most often unknown. As IVIG is a potentially valuable but also limited resource, we investigated the use of IVIG in our critically ill patients requiring extracorporeal membrane oxygenation (ECMO).

MATERIALS AND METHODS

Retrospective cohort study (April 2016 to March 2018) of adult patients with clinically suspected toxin-mediated shock requiring ECMO and who received IVIG in our regional severe respiratory failure (SRF)/ECMO center.

RESULTS

In 44% (15/34) of the patients, group A Streptococcus or Panton-Valentine Leukocidin producing S aureus was isolated. IVIG use in these patients was safe. The mortality was 30%, lower than the predicted mortality of >90% based on the SOFA scores.

CONCLUSION

IVIG administration can be considered in a selected group of patients presenting with acute and very severe septic shock.

Pulmonary ischaemia without pulmonary arterial thrombus in COVID-19 patients receiving extracorporeal membrane oxygenation: a cohort study

AIM

To evaluate the incidence of pulmonary ischaemia in COVID-19 patients on extracorporeal membrane oxygenation (ECMO), and its correlation with pulmonary artery thrombosis.

MATERIALS AND METHODS

Computed tomography (CT) thorax of all patients receiving ECMO with proven COVID-19 pneumonitis between March and May 2020 were analysed for the presence and extension of pulmonary thromboembolic disease.

RESULTS

Fifty-one patients were reviewed. The mean (range) age of 45 (26–66) years; 38/51 (74.5%) were men. All patients had severe COVID-19 pneumonitis, and 18/51 (35.3%) had macroscopic thrombosis (15 with associated ischaemia); however, 13/51 (25.5%) patients had ischaemia without associated thrombus.

CONCLUSION

The majority of patients with COVID-19 who received ECMO had areas of ischaemia within consolidated lungs, almost half of these without subtending pulmonary artery thrombosis. Although the prognostic significance of these findings is unclear, they are highly suggestive of lung ischaemia due to isolated microvascular immune thrombosis.

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High incidence of pulmonary artery thrombosis in COVID-19 ECMO patients.

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Lung ischaemia seen in patients with and without visible pulmonary artery thrombus.

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Ischaemia with no visible thrombus suggest microvascular thrombosis.

Image-proven thromboembolism in patients with severe COVID-19 in a tertiary critical care unit in the United Kingdom

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Venous thrombosis is common in patients with severe COVID-19 pneumonia.

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Many of these thromboses may be immunothromboses due to local inflammation, rather than thromboembolic disease.

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Anticoagulated patients with COVID-19 pneumonia have a risk of major bleeding.

Screening pulmonary angiogram and the effect on anticoagulation strategies in severe respiratory failure patients on venovenous extracorporeal membrane oxygenation

BACKGROUND

Venovenous extracorporeal membrane oxygenation in the treatment of severe respiratory failure in adults continues to increase with survival improving; however, it remains associated with serious complications.

OBJECTIVE

The aim of this study was to evaluate the prevalence of pulmonary embolism (PE) in patients with severe respiratory failure requiring venovenous extracorporeal membrane oxygenation (VV ECMO) and in those managed with conventional mechanical ventilation.

METHODS

A single-center, observational cohort, retrospective study was undertaken of patients with severe respiratory failure managed with conventional ventilation or requiring ECMO in a tertiary referral university teaching hospital.

RESULTS

We identified 343 patients with severe respiratory failure between January 2014 and December 2017. VV ECMO was used to support 290 patients and 53 were managed by conventional mechanical ventilation. The prevalence of PE was 9.6% (33/343), of which those supported with VV ECMO was 10% (29/290) and conventional ventilation 7.5% (4/53). There was no difference in survival rates between cohorts with PE versus no PE (ECMO survival to discharge P = .56; conventional ventilation survival to discharge P = .21).

CONCLUSIONS

The prevalence of pulmonary embolism in severe respiratory failure has important clinical implications for both short and long-term anticoagulation strategies. Routine screening pulmonary angiogram is warranted in this cohort.

Safety of Percutaneous Dilatational Tracheostomy During Veno-Venous Extracorporeal Membrane Oxygenation Support in Adults With Severe Respiratory Failure

OBJECTIVES

To investigate the safety of percutaneous dilatational tracheostomy in severe respiratory failure patients during veno-venous extracorporeal membrane oxygenation support.

DESIGN

A single-center, retrospective, observational cohort study.

SETTING

Tertiary referral severe respiratory failure center, university teaching hospital.

PATIENTS

Severe respiratory failure patients consecutively admitted and supported with veno-venous extracorporeal membrane oxygenation between January 2010 and December 2015.

INTERVENTION

A bronchoscopy-guided percutaneous dilatational tracheostomy was performed in all cases.

MEASUREMENTS AND MAIN RESULTS

Sixty-five veno-venous extracorporeal membrane oxygenation patients (median [interquartile range] age, 47 yr [interquartile range, 35-59 yr]; 39 males; Acute Physiology and Chronic Health Evaluation-II score, 18 [interquartile range, 17-22] Sequential Organ Failure Assessment score, 10 [interquartile range, 7-16]) underwent percutaneous dilatational tracheostomy. Ten patients (15%) developed one or more major complications. Of these, seven (11%) had major bleeding, and three of these also required circuit change due to extracorporeal membrane oxygenation circuit dysfunction. Two more patients (3.1%) presented with isolated extracorporeal membrane oxygenation circuit dysfunction requiring circuit change, and one developed bilateral pneumothoraces (1.5%) requiring intercostal drain insertion. Patients who developed complications had significantly lower extracorporeal membrane oxygenation postoxygenator PO2 prior to percutaneous dilatational tracheostomy (45.8 kPa [interquartile range, 36.9-56.5 kPa] vs 57.9 kPa [interquartile range, 45.1-64.2 kPa]; p = 0.019]. On multivariate analysis, including demographic, clinical, biochemical, hematologic variables, and extracorporeal membrane oxygenation circuit functional variables, extracorporeal membrane oxygenation postoxygenator PO2 was the only independent variable associated with major complications following percutaneous dilatational tracheostomy (beta = -0.09; odds ratio, 0.9; 95% CI, 0.84-0.99; p = 0.03).

CONCLUSIONS

Percutaneous dilatational tracheostomy is associated with a considerable complication rate in veno-venous extracorporeal membrane oxygenation patients. Preprocedure circuit performance as indicated by extracorporeal membrane oxygenation postoxygenator PO2 is an independent predictor of major complications following percutaneous dilatational tracheostomy.

How I treat heterozygous hereditary antithrombin deficiency in pregnancy

Untreated hereditary antithrombin deficiency in pregnancy is associated with maternal venous thromboembolism (VTE) and possibly with fetal loss. Thromboprophylaxis during pregnancy is recommended, but dosages remain controversial. Our objective was to perform a retrospective assessment of thrombotic events and pregnancy outcomes in women with hereditary antithrombin deficiency managed according to a standard protocol. Pregnancies in individuals with hereditary antithrombin deficiency were identified from a hospital database. Women with no prior VTE received enoxaparin 40 mg daily until 16 weeks gestation and thereafter 40 mg twice daily. Women with prior VTE received intermediate dose enoxaparin (1 mg/kg) once daily, increased to twice daily at 16 weeks and anti-Xa monitored dosing. Thromboprophylaxis was stopped at initiation of labour or 12 hours prior to caesarean and 50 IU/kg antithrombin concentrate given. Thromboprophylaxis was restarted after delivery. Eighteen pregnancies in 11 women with antithrombin deficiency were identified. Seventeen pregnancies (94%) were successful. Median gestation was 39 weeks (range 30–41) and median birth-weight was 2,995 g (910–4,120 g),but 6/17 infants (35%) were small for gestational age (p=0.01). Estimated blood loss at delivery was median 375 ml (200–600 ml). Four pregnancies were complicated by VTE; one newly presented with a thrombotic event, two patients were not taking thromboprophylaxis and one occurred despite thromboprophylaxis. Two novel mutations(p.Leu317Ser and p.His33GInfsX32) are described. In conclusion, in antithrombin deficiency the use of low-molecular-weight heparin in pregnancy and puerperium with antithrombin concentrate predelivery was associated with successful pregnancy outcome; rates of VTE appear to be lower than previously reported, but remain elevated

Where does the Albumin go? Human Albumin Solution usage following the implementation of a demand management programme

OBJECTIVE

To outline the Guy's and St Thomas' NHS Foundation Trust (GSTFT) and Evelina London Children's Hospital (ELCH) demand management plan for human albumin solution (HAS) and usage.

BACKGROUND

There is no UK-wide guidance governing the use of HAS. A severe shortage in 2015 prompted a Trust demand management programme. Indications were categorised according to locally agreed colour code and ASFA categories.

METHODS

Following the implementation of the demand management programme, a 6-month audit of HAS usage was completed.

RESULTS

A total of 1303.1 L of HAS was used in 1139 infusions; 737 infusions were 20% HAS, accounting for 175.7 L (13.5%) in 181 patients. Indications for 20% HAS were red in 53.9% (94.7 L), blue in 26.5% (46.5 L) and grey in 19.6% (34.5 L). The remaining 1127.4 L (86.5%) infused were of 4.5 and 5 % HAS. A total of 1102.3 L (97.8%) was used for plasma exchange, 941.4 L (85.4%) ASFA category I, 93.7 L (8.5%) category II, 25.5 L (2.3%) category IV and 41.7 L (3.8%) for indications not specified according to ASFA; 25.1 L (2.2%) were used for a grey indication (volume resuscitation for hypovolaemia).

CONCLUSIONS

The demand management programme provides surveillance of indications and retrospective verification of appropriate use. The majority of HAS indications were appropriate. Plasma exchange accounted for 84.6% of HAS usage and will be the focus of further demand management strategies. The demand management programme whilst aiming to promote best transfusion practice also ensures a tool to manage future shortages according to indication and available supply.

Blood conservation devices in critical care: a narrative review

Anaemia is associated with inferior outcomes in critically ill patients. It is difficult to prevent and is treated commonly with the transfusion of packed red cells. However, transfusion to augment oxygen delivery has not been shown to consistently offer a survival advantage when the haemoglobin concentration exceeds 7 g/dL. Several studies point to inferior outcomes when patients are transfused. Observational studies have confirmed that critically ill patients have frequent blood draws as part of their routine daily care. Cumulatively large volumes of blood are frequently taken, which contribute significantly towards the development of anaemia. Reducing iatrogenic blood loss may reduce the risk of developing anaemia and possibly the need for transfusion. Blood conservation devices may help to achieve this goal. The integration of blood conservation devices into routine care has been relatively slow in critical care. This review summarises the current evidence base and confirms that blood conservation devices do reduce the volume of iatrogenic blood loss. In the most recent studies, these devices have been shown to reduce transfusion requirements even in those intensive care units that follow a restrictive transfusion strategy.

Dependence of ammonia emissions from housing on the time cattle spent inside

Buildings housing cattle contribute 19% (42 kt NH3-N yr(-1)) of total UK ammonia (NH3) emissions. In the UK there is not usually an abrupt switch from cattle being kept inside to when they are turned out to graze 24 h a day. Moreover, during the summer dairy cows return to the farm twice a day to be milked and may spend some time inside buildings. Hence, there is uncertainty over the treatment of the transitional and summer periods when inventorying NH3 emissions. The aim of this study was to measure, under controlled and replicated conditions, the relationship between the number of hours cattle spend in buildings and the NH3 emissions from those buildings. Our results indicate that NH3 emissions decrease as the proportion of the day cattle spend in the buildings decreases, although the trend is not linear. Daily emission rates from cattle housed for 2 h ranged from 1.6 to 6.2 g NH3-N lu(-1) whereas emissions from cattle housed for 24 h ranged from 8.1 to 24.1 g NH3-N lu(-1). To significantly reduce NH3 emissions in comparison to those from buildings where cattle are housed for 24 h, the occupancy would have to be reduced to no more than 6 h each day. Thus, the strategy of extending the grazing season by allowing cattle to graze for c. 4 to 12 h during the winter is unlikely to reduce NH3 emissions from buildings or overall.

A phase II trial of docetaxel, thalidomide, bevacizumab, and prednisone in patients (pts) with metastatic androgen-independent prostate cancer (AIPC)

13037

Background: Angiogenesis plays a vital role in progression of prostate cancer. Antiangiogenic agents’ thalidomide (Td) and bevacizumab (Bv) have been shown in Phase II trials to enhance docetaxel (Doc) activity in metastatic AIPC. Td plus Doc also improved median overall survival as compared to Doc alone. Td and Bv have different antiangiogenic mechanisms. Td appears to affect bFGF, alter circulating endothelial cells and inhibit TNF expression; yet Td does not affect the target of Bv (VEGF). Since tumor angiogenesis is a complex interplay of multiple angiogenic factors, we reasoned that combination of mechanistically different antiangiogenic agents Td and Bv with Doc might be associated with an adequately high and durable PSA response to merit further study. Methods: Pts have progressive, metastatic AIPC, with no prior chemotherapy for AIPC, or prior Td or Bv. Treatment consists of Doc 75 mg/m2 plus Bv 15 mg/kg day 1, q 21 days as a cycle (C), plus Td 200 mg qhs and prednisone10 mg qd. Enoxaparin 1 mg/kg/d sq is used for thrombosis prevention. PSA is assayed q C and radiographic studies are performed at C 0, C 2, & then q 3 Cs. Results: To date, 22 of planned 60 pts have been enrolled, median age 65 [54–79], Gleason score 8 [Gs 6∼7: 32%, Gs 8∼10: 68%], on-study PSA 111 ng/ml [7.7–4399], & pre-treatment PSA doubling time 1.7 months [0.8–18.2]. I) All 22 pts are actively on trial without progression, with median treatment 6 Cs [1–12]. II) 20 pts treated ≥ 2 Cs, 17 (85%) had PSA declines of >50%, 2 declines of >20%, and 1 stable; median duration of >50% PSA decline is 5 Cs [0∼11]. III) 14 pts (of the 20) treated ≥ 5 Cs, 13 (93%) had >50% PSA declines; 6 of them also had measurable disease: 1 CR, 2 PR, & 3 SD (50% RR). IV) Significant toxicities include grade 4 neutropenia (11/22), grade 3 febrile neutropenia (3/22), syncope (2/22), & colon perforation (1/22). No thrombosis was seen. Conclusions: This trial tests a novel strategy of improving conventional treatment of metastatic AIPC. Our data show that the combination of two mechanistically different antiangiogenic agents Td and Bv with Doc does result in a high durable response in PSA (85∼93%) with acceptable toxicities, suggesting that further studies with the combination are warranted. Accrual is continuing.

No significant financial relationships to disclose.