Age Does Not Influence Postoperative Lactate Values in Older Adult Trauma Patients

Lactate monitoring is used to dynamically identify patients with a higher risk of poor outcomes. However, elevated lactate levels are interpreted using the same stratification regardless of patient age. Age could be a modifying factor for circulating lactate levels that has not been adequately examined. We hypothesized that there would be a negative association between age and lactate values in the geriatric population.

This retrospective observational study included patients ≥ 65 years old undergoing operative intervention between 1/1/2023 and 8/1/2023. Postoperative venous lactate (pVL) values and patients' age were examined continuously and categorically (pVL: < 2, 2-3, ≥ 3 mmol/L; age: 65-74, 75-84, ≥ 85 years). The association between pVL and age was analyzed overall and after stratifying by potential confounders: nonsurvival (morgue/hospice vs. other hospital disposition), ICU admission, injury severity (ISS ≥ 16 vs. < 16), and frailty (modified frailty index-5 ≥ 2 vs. < 2).

There were 284 surgically managed older adults; the median age was 80 (73-88) years and 37% were ≥ 85 years old. Overall, 218 (77%) patients had a pVL, assessed 8 (7-11) hours postoperatively. The median pVL was 1.8 (1.3-2.5) mmol/L and 13% had pVL ≥ 3 mmol/L. Age and pVL values were not associated when examined continuously (r² = 0.08, p = 0.20) nor categorically (p = 0.44). Age and pVL were not associated when stratified by ICU admittance (ICU: r² = 0.17, p = 0.44; non-ICU: r² = 0.07, p = 0.33), by ISS (≥ 16, r² = -0.03, p = 0.92; < 16: r² = 0.12, p = 0.09), by survival (survivors: r² = 0.08, p = 0.23; nonsurvivors: r² = -0.13, p = 0.64), and by frailty (frail: r² = 0.14, p = 0.15; not frail: r² = -0.07, p = 0.48).

These results suggest that age is not an important consideration or concern when interpreting postoperative lactate values of older adult trauma patients.