Renal Tubular Acidosis in Pregnant Critically Ill COVID-19 Patients: A Secondary Analysis of a Prospective Cohort

Simona Humbel; Pedro David Wendel-Garcia; Simone Unseld; Fabienne Noll; Reto Andreas Schuepbach; Christoph Camille Ganter; Harald Seeger; Sascha David; Rea Andermatt

doi:10.3390/jcm11154273

Renal Tubular Acidosis in Pregnant Critically Ill COVID-19 Patients: A Secondary Analysis of a Prospective Cohort

J Clin Med. 2022 Jul 22;11(15):4273. doi: 10.3390/jcm11154273.

Authors

Simona Humbel¹, Pedro David Wendel-Garcia¹, Simone Unseld¹, Fabienne Noll², Reto Andreas Schuepbach¹, Christoph Camille Ganter¹, Harald Seeger³, Sascha David¹, Rea Andermatt¹

Affiliations

¹ Institute of Intensive Care Medicine, University Hospital Zurich, 8091 Zurich, Switzerland.
² Department of Obstetrics, University Hospital Zurich, 8091 Zurich, Switzerland.
³ Division of Nephrology, University Hospital Zurich, 8091 Zurich, Switzerland.

Abstract

Background: Renal tubular acidosis (RTA) is an extremely rare cause of metabolic acidosis (10 in 100,000). RTA has been linked neither to pregnancy nor to severe coronavirus disease 2019 (COVID-19). The purpose of this study was to analyze the prevalence and clinical course of normal anion gap metabolic acidosis in critically ill pregnant COVID-19 patients and to compare them to an age-matched nonpregnant female patient cohort.

Methods: Secondary analysis was conducted on a prospective observational cohort of critically ill patients suffering from COVID-19 consecutively admitted to a tertiary intensive care unit (ICU) between February 2020 and April 2021.

Results: A total of 321 COVID-19 patients required admission to the ICU; 95 (30%) were female, and 18 (19%) were of childbearing age. Seven of eight (88%) pregnant women (all in the last trimester) required advanced respiratory support due to COVID-19. The estimated glomerular filtration rate was 135 (123-158) mL/min/m² body surface area, and six pregnant women (86%) were diagnosed with a normal, respiratory compensated, anion gap metabolic acidosis (pH_min 7.3 (7.18-7.31), HCO₃^-_min 14.8 (12.8-18.6) mmol/L, and paCO₂ 3.4 (3.3-4.5) kPa). Three (43%) acidotic pregnant women fulfilled diagnostic criteria for RTA. All women recovered spontaneously within less 7 days.

Conclusions: Metabolic acidosis seems to be very common (85%) in pregnant critically ill COVID-19 patients, and the prevalence of RTA might be higher than normal. It remains to be demonstrated if this observation is an indirect epiphenomenon or due to a direct viral effect on the tubular epithelium.

Keywords: acidosis; acid–base; intensive care unit; kidney; pregnancy; renal; tubular.

Grants and funding

Funding was solely provisioned from internal resources of the Institute of Intensive Care Medicine, University Hospital of Zurich, Zurich, Switzerland. S.D. is supported by the DFG (DA1209/4-3, pending DA1209/7-1), Schweizerischer Nationalfonds (SNF 310030 208100), the Deutsches Zentrum Lungenforschung (DZL), Terumo, Octapharma, and Cytosorbents.