In the Literature

Summary of "Indexed Delivery of Oxygen Predicts In-hospital Mortality and Morbidity in Reoperative Adult Cardiac Surgery Patients: A Retrospective Cohort Study"

Summary published August 24, 2026

Summary by Gabriel Garcia Barrera, MD; Yong G. Peng MD, PhD, FASE, FASA

Journal of Cardiothoracic and Vascular Anesthesia | January 2026

Rubino AS, De Santo LS, Torella M, Montella AP, Golini Petrarcone C, Palmieri L, Galbiati D, Pisano A, Pappalardo F, De Feo M. Indexed Delivery of Oxygen Predicts In-hospital Mortality and Morbidity in Reoperative Adult Cardiac Surgery Patients: A Retrospective Cohort Study. J Cardiothorac Vasc Anesth. 2026 May;40(5):1373-1380. doi: 10.1053/j.jvca.2026.01.002. Epub 2026 Jan 3. PMID: 41582053.

doi: https://doi.org/10.1053/j.jvca.2026.01.002

  • Cardiac surgery is associated with a high risk of mortality, particularly in complex or redo operations.
  • During cardiopulmonary bypass, tissue perfusion and oxygenation are dependent on extracorporeal oxygenation systems (bypass machines).
  • Indexed oxygen delivery (DO2i), a derived measurement of oxygen delivery to tissues (expressed in units of milliliters of oxygen per minute per square meter of body surface area), is a useful marker for tissue perfusion and end-organ function, particularly during cardiopulmonary bypass.
  • This retrospective cohort study, conducted at a single tertiary academic medical center, analyzed 343 adults undergoing reoperative cardiac surgery (2011-2021) to assess whether DO2i during cardiopulmonary bypass predicts outcomes.
  • The cohort had a high baseline risk profile: 58% anemia, 30.9% chronic kidney disease, 20.7% diabetes, reflecting a complex surgical population.
  • Overall in-hospital mortality was 14.6%, with median DO2i of 300.8 ± 52.3 mL/min/m2.
  • A DO2i threshold of ~289 mL/min/m2 was identified as critical, with values below this associated with a fourfold increase in risk of mortality (OR 4.12).
  • Each 1 mL/min/m2 decrease in DO2i increased mortality by 1.6% (OR 1.016).
  • Even after adjusting for differences in patient risk factors, patients with a DO2i <298.4 mL/min/m² had worse postoperative outcomes. Low DO2i remained independently associated with higher in-hospital mortality (21.6% vs 6.6%), increased acute kidney injury, greater cardiac complications, and more prolonged mechanical ventilation. These patients were also more likely to have longer cardiopulmonary bypass (CPB) times, suggesting they may have undergone more complex or difficult surgeries.
  • Adjusted analyses showed an absolute mortality increase of ~15% (Average Treatment Effect 0.151) in low DO2i patients, confirming it as an independent predictor.
  • Limitations of the study include its single-center retrospective design, lack of continuous DO2i monitoring, and heterogenous risk profiles that limit generalizability.
  • Prospective studies are needed to validate thresholds and assess optimal DO2i-guided perfusion strategies.