Eight patients were placed on VV ECMO during the covid pandemic for severe SARS-nCoV2 ARDS diagnosed with RT-PCR during the period from 01 June 2020 to 30 May 2022, which were admissions direct or referred. Data were collected retrospectively from the hospital's electronic health records after approval by the hospital ethics committee with a waiver of consent due to the ongoing pandemic.
All Patients on VV-ECMO had received intravenous dexamethasone, Remdesivir, Tocilizumab, low molecular weight heparin, and antibiotics based on the culture sensitivity, along with oxygen support with variable or fixed oxygen delivery devices e.g., High flow nasal oxygen (HFNO) and with Non-invasive ventilation (NIV) support based on the clinical condition of the patients. If the patient had deteriorated despite the optimal medical treatment described above, the patients were intubated and ventilated using volume control mode (VCV) using lung protection ventilation (LPV) strategies, and they were also ventilated in a prone position if the PaO2/FiO2 ratio was < 150. After excluding the contraindications for ECMO i.e., history of stroke with neurological deficits, malignancies, end-stage renal disease, mechanical ventilation for more than 14 days, patients on high doses of vasopressors a decision to initiate ECMO was done by the intensivist after explaining the risks vs benefits to the patient relatives and written informed consent was taken either telephonically or through video conference.
During the initial phases of the pandemic, there was an acute surge of patients, and due to a lack of adequate resources and ethical issues such as distributive justice, a very limited number of patients were selected for ECMO placement. The Criteria for initiation of ECMO were strictly based on the EOLIA trial, if a patient was in hypoxic respiratory failure despite optimal ventilation strategies that are, respiratory rate > 35/min, tidal volume of 6ml/kg of predicted body weight, Plateau pressures greater than 32 cm H2O, PEEP > 10 cm H2O, FiO2 > 80%, with a PaO2/FiO2 ratio of < 50 mmHg for at least 3h, or a PaO2/FiO2 ratio of < 80 mmHg for at least 6 h or an arterial blood gas (ABG) showing a pH of < 7.25 with a paCO2 ≥ 60 mmHg for at least 6 h with anticipated prolonged ventilation for > 7 days and a Murray score of > 3 with a single organ failure (3). Appropriate personal protective equipment (PPE) was used with a restricted entry to the number of people during the cannulation procedure. A 2D echocardiography was done before cannulation for evaluating the right and left ventricular dysfunction,
The usual site for cannulation was in the right femoral vein for the drainage with a return cannula placed in the right internal jugular vein (IJV). The size of cannulas selected was dependent on the height, weight, and body surface area (BSA) of the patient. A size 22 to 27 Fr was used for drainage along with a size 17–21 Fr for the placement of the return cannula.
Percutaneous placement of the cannula was done using Seldinger’s technique ultrasonography (USG). A 2D echocardiography was used to correct the placement of the guidewire and a 15 cm distance was maintained between the drainage and the return cannulas to prevent recirculation. Femoral-femoral cannulation was used only in one patient and was unviable due to the increased risk of recirculation and worsening of gas exchange. The flow rate was titrated by controlling the rpm on the ECMO console to maintain a flow of 60–80 ml/kg/min to improve oxygenation, with the sweep gas flow adjusted accordingly. Intravenous bolus heparin was used at a dose of 60–80 units per kg body weight after both the guide wires were inside, which was followed by a continuous infusion with a target ACT of 180–220 seconds or APTT target of 60–80 seconds. The tests were carried out at regular intervals to maintain an optimal level of anticoagulation. Sedation and paralysis were down-titrated as tolerated by the patients. Daily arterial blood gas was performed to titer the sweep gas and FiO2. Serial measurements of reactive C protein, D dimer, lactate dehydrogenase (LDH), and procalcitonin were also done every 48- 72h. The withdrawal from VV ECMO was performed if the patient remained stable with a fresh gas flow of 0 L/min for at least 4–6 hours or was left to the discretion of the intensivist.
Statistical analysis
Continuous variables are presented as median (interquartile range [IQR]), while categorical variables are expressed as percentages (%). Statistical analyses are done using MS excel.