Case series
Patient 1: A 42-year-old, hypertensive gentleman presented with unstable angina and was diagnosed with triple vessel coronary artery disease by left heart catheterization. His initial hemodynamics and labs were within normal limits and are described in Table 1. Pre-operative arterial blood gas (ABG) analysis was normal on room air (Table 2). Patient tested negative for COVID-19 by reverse transcription polymerase chain reaction (RT-PCR) one day prior to the CABG procedure.
The patient underwent on-pump CABG x 3 (left internal mammary artery to the left anterior descending artery, sequential saphenous vein graft to the posterior descending and obtuse marginal arteries). The surgery was carried out uneventfully and the intra-operative ABG on a fraction of inspired oxygen (FiO2) of 70% is depicted in Table 2. The patient was weaned off cardio-pulmonary bypass on no inotropes, and a small dose of vasopressor. In the intensive care unit, the first ABG on a FiO2 of 100% was abnormal with a partial pressure of oxygen (PO2) of 69 mmHg (Table 2). A few hours after surgery, the patient became hypotensive with low cardiac indices. An epinephrine infusion was started, and vasopressors were escalated. The patient was initially dyssynchronous on the ventilator and needed deepened sedation. He continued to have low arterial saturations on escalating ventilatory support over the next 24-48 hours. A repeat COVID-19 RT-PCR was sent due to the ongoing difficulty with ventilation, which returned positive on post-operative day (POD)-2.
On POD-3, the patient was placed on peripheral veno-venous extracorporeal membrane oxygenation (VV-ECMO). He responded well on ECMO with improved arterial saturations. The ECMO run was complicated by positive blood cultures, for which antibiotics were escalated. A percutaneous tracheostomy was performed on POD-15. After being supported on VV-ECMO for 18 days, the patient was successfully weaned off and decannulated. He was then slowly weaned off the ventilator and after being on the tracheostomy for 22 days, he was then decannulated and was discharged home.
Patient 2: A 62-year-old morbidly obese lady with sleep apnea, type-2 diabetes mellitus, chronic obstructive pulmonary disease on home oxygen, and hypertension presented to the hospital with non-ST elevation myocardial infarction. Her initial hemodynamics and labs were within normal limits (Table 1) except a random blood sugar of 322 mg/dl, with a HbA1c of 9.2%. Coronary angiography revealed critical three-vessel disease. Her chest x-ray revealed bronchopneumonia of right lower lobe, for which antibiotics were initiated. Her pre-operative ABG on 3 liters of oxygen/minute is depicted in Table 2. She tested negative for COVID-19 six days prior to surgery by RT-PCR.
After medical optimization, she underwent on-pump CABG x 3 (left internal mammary artery to the left anterior descending artery and individual reverse saphenous vein grafts to the obtuse marginal and right coronary arteries). The surgery was carried out uneventfully, and she left the operating room on no inotropes or vasopressors. Post-operatively, she developed hypoxia with escalating PEEP and FiO2 requirements (Table 2). Her cardiac indices were borderline low, and she was started on an epinephrine and milrinone infusion. The ventilatory struggles continued for the next 48-72 hours, with the patient being dyssynchronous on the ventilator, responding marginally to ketamine infusion. On POD-6, RT-PCR for COVID-19 returned positive, and she was started on remdesivir. There was marginal improvement in oxygenation, and she was supported on the ventilator for another 7 days. On POD-14, she was placed on peripheral VV-ECMO. She initially responded well to ECMO, but later developed heparin-induced thrombocytopenia (HIT). She also had intermittent fevers, with escalating antibiotic requirements. A percutaneous tracheostomy was also performed. However, she showed improvement from a respiratory standpoint, and after 12 days on ECMO support, she was weaned off and decannulated. The patient then remained stable for 24-48 hours, but then started developing significantly elevated liver function markers with abdominal distention. A rising serum lactate levels led to the suspicion of bowel ischemia, and an exploratory laparotomy was performed. The laparotomy revealed extensive small bowel ischemia, and given the extent of the disease, a decision was reached with the family to make her comfort care.