BMC Anesthesiology (Oct 2024)

Association between delta anion gap/delta bicarbonate and outcome of surgical patients admitted to intensive care unit

  • Pedro Ferro Lima Menezes,
  • Ricardo Esper Treml,
  • Tulio Caldonazo,
  • Hristo Kirov,
  • Bruno Caldin da Silva,
  • Amanda Maria Ribas Rosa de Oliveira,
  • Cristina Prata Amendola,
  • Fábio Barlem Hohmann,
  • Luiz M. Sá Malbouisson,
  • João Manoel Silva Jr

DOI
https://doi.org/10.1186/s12871-024-02564-z
Journal volume & issue
Vol. 24, no. 1
pp. 1 – 11

Abstract

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Abstract Background Patients undergoing high-risk surgeries with acid-based disorders are associated with poor outcomes. The screening of mixed acid-based metabolic disorders by calculating delta anion gap (AG)/delta bicarbonate (Bic) has a clinically relevant role in patients with high AG metabolic acidosis (MA), however its utility in individuals facing high-risk surgical procedures remains unclear. Objective Characterize metabolic acidosis using delta-AG/delta-Bic and its associations in patients undergoing high-risk surgeries with possible outcome-related complications. Design Prospective observational multicentric study. Setting Three tertiary hospitals in Brazil. Patients Patients undergoing high-risk surgeries, aged 18 years or older, requiring postoperative critical care. Main outcome measures Patients undergoing high-risk surgeries monitored during the postoperative phase across three distinct intensive care units (ICUs), with assessment encompassing laboratory analyses upon admission and 24 h thereafter. Patients with MA and with elevated AG within 24 h were separated into 3 subgroups: [G1 – delta-AG/delta-Bic 1.6] MA associated with alkalosis. Primary endpoint was 30-day mortality. The secondary endpoints were cardiovascular, respiratory, renal, neurological, coagulation and infective complications. Results From the 621 surgical patients admitted to ICU, 421 (51.7%) had any type of acidosis. After 24 h, 140 patients remained with MA with elevated AG (G1: 101, G2: 18, and G3: 21). When compared to patients from subgroups 1 and 3, the subgroup with no mixed disorders 2 showed higher 30-day mortality (adjusted HR = 3.72; 95% CI 1.11–12.89, p = 0.001), cardiovascular complications (p = 0.001), ICU mortality (p = 0.03) and sum of all complications during the ICU period (p = 0.021). Conclusion In the postoperative time, patients with metabolic acidosis and no mixed disorders present higher ICU-Mortality and higher cardiovascular postoperative complications when compared with patients with combined hyperchloremia or alkalosis. Delta-AG/delta-Bic can be a useful tool to evaluate major clinical outcomes in this population.

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