Nebulised Heparin in Patients With Severe COVID-19

Inclusion Criteria: * Age 18 years or older * Currently in an intensive care unit (ICU) or scheduled for transfer to the ICU. During the pandemic, critically ill inpatients might be cared for outside of the walls of the usual physical environment of ICU. For this reason, ICU is defined as an area designated for inpatient care of the critically ill where therapies including invasive mechanical ventilation can be provided. * Endotracheal tube in place * Intubated yesterday or today * PaO2 to FIO2 ratio less than or equal to 300 while intubated * Acute opacities not fully explained by effusions, lobar/lung collapse and nodules, affecting at least one lung quadrant on chest X-ray or CT * The acute opacities on chest X-ray or CT are most likely due to COVID-19 * There is a PCR positive sample for SARS-CoV-2 within the past 21 days or there are results pending or further testing is planned. The sample can be a nasal or pharyngeal swab, sputum, tracheal aspirate, bronchoalveolar lavage, or another sample from the patient. Exclusion Criteria: * Enrolled in another clinical trial that is unapproved for co-enrolment * Heparin allergy or heparin-induced thrombocytopaenia (HIT) * APTT \> 120 seconds and this is not due to anticoagulant therapy * Platelet count \< 20 x 109 per L * Pulmonary bleeding, which is frank bleeding in the trachea, bronchi or lungs with repeated haemoptysis or requiring repeated suctioning * Uncontrolled bleeding * Pregnant or might be pregnant. Females aged 18…