Cerebral oximetry and cognitive dysfunction in elderly patients undergoing surgery for hip fractures: a prospective observational study

Aim:

This study was conducted to examine perioperative cerebral oximetry changes in elderly patients undergoing hip fracture repair and evaluate the correlation between regional oxygen saturation (rSO₂) values, postoperative cognitive dysfunction (POCD) and hospital stay.

Materials and Methods:

This prospective observational study included 69 patients. Data recorded included demographic information, rSO₂ values from baseline until the second postoperative hour and Mini Mental State Examination (MMSE) scores preoperatively and on postoperative day 7. MMSE score ≤23 was considered evidence of cognitive dysfunction. Postoperative confusion or agitation, medications administered for postoperative agitation, and hospital length of stay were also recorded. Data were analyzed with Student’s t-test, Pearson’s correlation or multiple regression analysis as appropriate.

Results:

Patient age was 74±13 years. Baseline left sided rSO₂ values were 60±10 and increased significantly after intubation. Baseline rSO₂ L<50 and <45 was observed in 11.6% and 10.1% of patients respectively. Perioperative cerebral desaturation occurred in 40% of patients. MMSE score was 26.23 ± 2.77 before surgery and 25.94 ± 2.52 on postoperative day 7 (p=0.326). MMSE scores ≤ 23 were observed preoperatively in 6 and postoperatively in 9 patients. Patients with cognitive dysfunction had lower preoperative hematocrit, hemoglobin, SpO₂ and rSO₂ values at all times, compared to patients who did not. There was no correlation between rSO₂ or POCD and hospital stay. Patients with baseline rSO₂ <5 required more medications for postoperative agitation.

Conclusion:

Cognitive dysfunction occurs preoperatively and postoperatively in elderly patients with hip fractures, and is associated with low cerebral rSO₂ values.

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

AIM

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.

PATIENTS AND METHODS

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.

RESULTS

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.

CONCLUSION

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.

Importance of perioperative monitoring of cerebral tissue saturation in elderly patients: an interesting case

The authors describe the case of an elderly diabetic patient with a hip fracture who developed neurocognitive dysfunction and dysarthria preoperatively. Upon arrival in the operating room, the monitoring of cerebral oxygenation by near-infrared spectroscopy (NIRS) showed cerebral desaturation (44% on the left hemisphere and 46% on the right). Cerebral oximetry values were stabilized during the surgery after administration of crystalloid fluids and vasoconstrictive drugs and were ameliorated significantly after administration of two units of blood. The patient's cerebral saturation was 60% on the left and 58% on the right hemisphere after the end of surgery and he was in normal neurological status. Observations underlined the importance of preoperative evaluation of cerebral tissue oxygenation by non-invasive cerebral NIRS in elderly diabetic patients who develop hypovolemia and anemia due to major fracture.