Intraoperative Arterial Waveform Morphology Trajectories and Prediction of Postoperative Acute Kidney Injury: A Latent-Class Analysis of the VitalDB Registry.

Background

Intraoperative hypotension is an established risk factor for postoperative acute kidney injury (AKI), but whether arterial waveform morphology adds prognostic information beyond the hypotension burden is unknown.

Methods

In this study, 2587 adult surgical cases from the Vital Signs Database (VitalDB) with continuous invasive arterial waveforms and creatinine-based (KDIGO) AKI ascertainment were analyzed retrospectively. Maximal systolic upstroke (dP/dtmax), a late-diastolic pressure-decay descriptor (τ), and a waveform-derived dynamic arterial elastance (Eadyn), modeled as latent-class trajectories and as case-level features, were added to a base logistic model of log-transformed hypotension burden (time-weighted MAP < 65 mmHg), age, sex, and baseline eGFR.

Results

AKI occurred in 143 cases (5.5%); the base model had an AUC of 0.725 (95% CI 0.680-0.770). A five-class dP/dtmax solution yielded distinct phenotypes whose membership was nominally associated with AKI (likelihood-ratio p = 0.02) but did not improve discrimination (change in AUC (ΔAUC), 0.008, 95% CI -0.005 to 0.021; optimism-corrected 0.002), and the association was attenuated after clinical adjustment (p = 0.13); τ showed no stable trajectory structure. No feature improved discrimination: the optimism-corrected ΔAUC was ≤0.007, upper confidence limits did not exceed 0.03 on any adequately fitting reference model, and the signal disappeared after adjustment for procedure type and comorbidity. The likelihood-ratio test had 80% power for a ΔAUC of 0.009.

Conclusions

Arterial waveform morphology did not improve prediction of postoperative AKI beyond the hypotension burden; overall, these data exclude an incremental gain larger than approximately 0.02-0.03 AUC units.