Continuous Bilateral Lower-Limb Near-Infrared Spectroscopy Monitoring in Patients on Intra-aortic Balloon Pump Support: A Prospective Feasibility and Physiology Study.

OBJECTIVES

To evaluate the feasibility of continuous bilateral lower-limb near-infrared spectroscopy (NIRS) monitoring as an adjunct to standard hourly neurovascular assessment (NVA) in patients receiving intra-aortic balloon pump (IABP) support, and to characterize the relationship between regional oxygen saturation (rSO₂) and in-hospital mortality.

DESIGN

Prospective observational cohort study.

SETTING

Cardiac care unit of a tertiary cardiac center (Tan Tock Seng Hospital, Singapore).

PARTICIPANTS

Fifty consecutive adult patients receiving IABP support via femoral arterial access.

INTERVENTIONS: Continuous bilateral lower-limb rSO₂ monitoring using NIRS was performed throughout IABP support, alongside standardized hourly NVA of both limbs (capillary refill time, skin color, temperature, pulse quality, and Doppler signal).

MEASUREMENTS AND MAIN

RESULTS

Right femoral access was used in 94% of patients (47 of 50). Minimum contralateral (left) rSO₂ was significantly lower in nonsurvivors than survivors (29.3% ± 17.6% v 43.3% ± 14.4%, p = 0.024), with a directionally similar but nonsignificant trend on the ipsilateral (right) side (p = 0.083). Regional oxygen saturation correlated moderately with capillary refill time (Spearman rank correlation [rs] ≈ 0.50) and pulse quality (rs ≈ 0.38) bilaterally but not with temperature change, which deteriorated in >92% of limbs. Low rSO₂ (<40%) in either limb was associated with a nonsignificant 3.16-fold increase in mortality odds (95% confidence interval, 0.55-18.11; p = 0.197). No patient developed acute limb ischemia. Sepsis (odds ratio [OR], 13.0) and renal replacement therapy (OR, 7.1) were the only statistically significant predictors of mortality.

CONCLUSIONS

Continuous bilateral lower-limb rSO₂ monitoring is feasible throughout IABP support and produces a physiologically coherent signal that correlates moderately with objective NVA parameters and is lower in patients who do not survive to discharge. No limb ischemic events occurred; these findings are best regarded as feasibility and physiology data rather than evidence that continuous monitoring improves limb outcomes, and they warrant confirmation in a larger, multicenter study.