METABOLIC ALKALOSIS DRIVING RESPIRATORY FAILURE IN POST ACUTECOVID-19 SYNDROME

Abstract

TOPIC: Pulmonary Physiology TYPE: Medical Student/Resident Case Reports INTRODUCTION: Survival of the acute phase of COVID-19 infection can leave patients with multiple long-term sequelae described as Post-acute covid-19 syndrome (PACS). We present a case of a patient with PACS manifested as pulmonary fibrosis, carbon dioxide retention and difficulty weaning from BIPAP that experienced dramatic improvement following treatment with Acetazolamide. CASE PRESENTATION: 66-year-old female presented for 7 days of worsening cough and shortness of breath. She was found to be hypoxic on presentation with COVID-19 test resulting positive and was admitted. Her hospital course was complicated by rapid increase in oxygen requirements with the initiation of BIPAP on hospital day 19. At this time, arterial blood gas (ABG) revealed mixed respiratory acidosis and metabolic alkalosis with pH 7.41, CO2 77 and HCO3 of 43. She was continued on BIPAP for several days before being weaned to high flow nasal cannula. On hospital day 44 she was noted to be increasingly lethargic. ABG obtained at this time showed pH of 7.3, CO2 >110 and HCO3 of 68. She was placed back on BIPAP and serial ABGs were monitored. At about 12 hours after the initiation of BIPAP, she developed a post-hypercapnic alkalosis with ABG demonstrating pH 7.46, CO2 90 and HCO3 50. At this time, BIPAP was stopped and Acetazolamide was administered at 500mg IV daily for 2 days.The patient experienced significant improvement in her mental status and work of breathing. She was weaned to nasal cannula. An ABG obtained the day following the second acetazolamide dose showed improvement in both metabolic alkalosis and respiratory acidosis with pH 7.42, CO2 62 and HCO3 34. DISCUSSION: The role of correcting metabolic alkalosis in hypercapnic respiratory failure has been described over the years. Trials conducted have utilized the carbonic anhydrase inhibitor Acetazolamide to promote renal bicarbonate excretion with goal statistical endpoints of early liberation from mechanical ventilation, reduced hospital stay or mortality but have generally failed to demonstrate statistically significant benefit.In the DIABOLO trial, mechanically ventilated COPD patients with metabolic alkalosis were assigned to either Acetazolamide infusion or placebo. The study concluded without statistically significant benefit in the primary outcome (duration of mechanical ventilation) or important secondary outcomes such as ICU mortality or ICU length of stay. However, the average serum bicarbonate level was only 27 between the two groups. This leads to the question if acetazolamide may have benefits in specific patients with a more severe alkalosis in the right clinical context as shown in this case study. CONCLUSIONS: Alkalosis may surpass compensation and perpetuate hypercapnic respiratory failure. This may be especially common ARDS patients managed with a fluid restricted approach. Administration of acetazolamide may benefit appropriately selected patients. REFERENCE #1: Nalbandian A, Sehgal K, Gupta A, et al. Post-acute COVID-19 syndrome. Nat Med. Published online March 22, 2021. doi:10.1038/s41591-021-01283-z REFERENCE #2: Faisy C, Meziani F, Planquette B, et al. Effect of Acetazolamide vs Placebo on Duration of Invasive Mechanical Ventilation Among Patients With Chronic Obstructive Pulmonary Disease: A Randomized Clinical Trial. JAMA. 2016;315(5):480-488. doi:10.1001/jama.2016.0019 REFERENCE #3: Adamson R, Swenson ER. Acetazolamide Use in Severe Chronic Obstructive Pulmonary Disease. Pros and Cons. Ann Am Thorac Soc. 2017;14(7):1086-1093. doi:10.1513/AnnalsATS.201701-016FR DISCLOSURES: No relevant relationships by Jackson Heilbronn, source=Web Response no disclosure on file for Christina Kwon;No relevant relationships by Michael Ulrich, source=Web Response