Evaluation of the Acid-Base Status in Patients Admitted to the ICU Due to Severe COVID-19: Physicochemical versus Traditional Approaches

Zoi Sotiropoulou; Elvira Markela Antonogiannaki; Evangelia Koukaki; Stavroula Zaneli; Agamemnon Bakakos; Angelos Vontetsianos; Nektarios Anagnostopoulos; Nikoleta Rovina; Konstantinos Loverdos; Paraskevi Tripolitsioti; Magdalini Kyriakopoulou; Konstantinos Pontikis; Petros Bakakos; Dimitrios Georgopoulos; Andriana I Papaioannou

doi:10.3390/jpm13121700

Evaluation of the Acid-Base Status in Patients Admitted to the ICU Due to Severe COVID-19: Physicochemical versus Traditional Approaches

J Pers Med. 2023 Dec 11;13(12):1700. doi: 10.3390/jpm13121700.

Authors

Zoi Sotiropoulou¹, Elvira Markela Antonogiannaki², Evangelia Koukaki¹, Stavroula Zaneli¹, Agamemnon Bakakos¹, Angelos Vontetsianos¹, Nektarios Anagnostopoulos¹, Nikoleta Rovina¹, Konstantinos Loverdos¹, Paraskevi Tripolitsioti¹, Magdalini Kyriakopoulou¹, Konstantinos Pontikis¹, Petros Bakakos¹, Dimitrios Georgopoulos³, Andriana I Papaioannou¹

Affiliations

¹ 1st Department of Respiratory Medicine, National and Kapodistrian University of Athens, School of Medicine, Sotiria Chest Hospital, Mesogeion 152, 11527 Athens, Greece.
² 4th Department of Respiratory Medicine, Sotiria Chest Hospital, 11527 Athens, Greece.
³ Intensive Care Medicine Department, University Hospital of Heraklion, Medical School, University of Crete, 71110 Heraklion, Greece.

Abstract

Background: Stewart's approach is known to have better diagnostic accuracy for the identification of metabolic acid-base disturbances compared to traditional methods based either on plasma bicarbonate concentration ([HCO₃^-]) and anion gap (AG) or on base excess/deficit (BE). This study aimed to identify metabolic acid-base disorders using either Stewart's or traditional approaches in critically ill COVID-19 patients admitted to the ICU, to recognize potential hidden acid-base metabolic abnormalities and to assess the prognostic value of these abnormalities for patient outcome.

Methods: This was a single-center retrospective study, in which we collected data from patients with severe COVID-19 admitted to the ICU. Electronical files were used to retrieve data for arterial blood gases, serum electrolytes, and proteins and to derive [HCO₃^-], BE, anion gap (AG), AG adjusted for albumin (AG_adj), strong ion difference, strong ion gap (SIG), and SIG corrected for water excess/deficit (SIG_corr). The acid-base status was evaluated in each patient using the BE, [HCO₃^-], and physicochemical approaches.

Results: We included 185 patients. The physicochemical approach detected more individuals with metabolic acid-base abnormalities than the BE and [HCO₃^-] approaches (p < 0.001), and at least one acid-base disorder was recognized in most patients. According to the physicochemical method, 170/185 patients (91.4%) had at least one disorder, as opposed to the number of patients identified using the BE 90/186 (48%) and HCO₃ 62/186 (33%) methods. Regarding the derived acid-base status variables, non-survivors had greater AG_adj, (p = 0.013) and SIG_corr (p = 0.035) compared to survivors.

Conclusions: The identification of hidden acid-base disturbances may provide a detailed understanding of the underlying conditions in patients and of the possible pathophysiological mechanisms implicated. The association of these acid-base abnormalities with mortality provides the opportunity to recognize patients at increased risk of death and support them accordingly.

Keywords: COVID-19; acid–base disorders; base excess; intensive care unit; physicochemical approach.

Grants and funding

This research received no external funding.