Baseline cerebral oximetry values in elderly patients with hip fractures: a prospective observational study

This study was conducted to evaluate baseline cerebral tissue regional oxygen saturation (rSO(2)) values and identify risk factors related to severe rSO(2) reductions in elderly patients with hip fractures.

This was a prospective observational single-centre study on patients undergoing scheduled or urgent operation for isolated hip fracture. The study was approved by the Institution Ethics Committee, and all patients signed informed consent before entering the study. Data were collected on factors potentially related to baseline cerebral rSO(2). Data were analysed with Student's t-test, Pearson's correlation or multiple regression analysis as appropriate.

Sixty-nine patients, aged (mean±standard deviation (SD)) 74±13 years participated. Left baseline rSO(2) was 60.09±10.20 and right baseline rSO(2) was 58.64±9.92. Baseline rSO(2)<45 was observed in 10.1% of patients on the left and 8.7% on the right side. Correlation between left- and right-side baseline cerebral rSO(2) was highly significant (r=0.852, p<0.001). Baseline cerebral rSO(2) had a positive, highly significant correlation with preoperative haematocrit (r=0.50, p<0.001) and arterial haemoglobin oxygen saturation (SpO(2)) (r=0.587, p<0.001), but correlation was negative with the American Society of Anesthesiologists (ASA) physical status (r=-0.42, p<0.001) and age (r=-0.39, p=0.001). Linear regression showed that preoperative haematocrit accounts for 23% (R(2)=0.23) of baseline rSO(2) variability, whereas preoperative haematocrit and SpO(2) combined account for 43.7% of rSO(2) variability (R(2)=0.437). Combined preoperative haematocrit+SpO(2)+age accounted for 51.3% (R(2)=0.513) of observed rSO(2) variability.

Low baseline cerebral rSO(2) values are common in elderly hip fracture patients, despite normal haemodynamic and arterial saturation values. Preoperative haematocrit, SpO(2) and age explain a significant portion of cerebral rSO(2) variability. More studies are needed to validate our findings and assess the potential benefit of interventions aimed at improving cerebral rSO(2) in elderly hip fracture patients.