Original article
The Relationship Between Cerebral Oxygen Saturation Changes and Postoperative Cognitive Dysfunction in Elderly Patients After Coronary Artery Bypass Graft Surgery

https://doi.org/10.1053/j.jvca.2010.03.019Get rights and content

Objective

The aim of this study was to evaluate the predictive value of cerebral regional oxygen saturation (rSO2) in the occurrence of postoperative cognitive dysfunction (POCD) in elderly patients undergoing coronary artery bypass graft (CABG) surgery.

Design

A prospective study.

Setting

University hospital.

Participants

A total of 61 patients (84% male) with a mean age of 70.39 ± 4.69 on a waiting list for CABG surgery were enrolled in the study.

Intervention

A complete neurocognitive evaluation was performed 1 day before surgery as well as 4 to 7 days and 1 month after surgery. During surgery, rSO2 was monitored continuously.

Measurements and Main Results

POCD was defined as a reduction of 1 standard deviation on 2 or more neuropsychologic indices. Forty-six patients (80.7%) developed early POCD, and 23 (38.3%) showed late POCD. Patients whose rSO2 decreased to less than 50% during the surgery experienced more POCD 4 to 7 days after surgery (p = 0.04). In addition, a decrease of more than 30% from the patient's baseline rSO2 was associated with POCD 1 month after surgery (p = 0.03).

Conclusion

Intraoperative cerebral oxygen desaturation is associated with early and late POCD in elderly patients. Cerebral oximetry is a promising tool in the prediction of subtle neuropsychologic deficits and further studies are needed.

Section snippets

Methods

After approval by the institutional review board and after obtaining written informed consent, 76 patients at least 65 years of age undergoing CABG surgery were recruited between January 2006 and September 2008 at a tertiary care hospital.

Inclusion criteria were as follows: (1) scheduled for a primary CABG surgery, (2) 65 years of age or older, and (3) able to speak and read French. Exclusion criteria were as follows: (1) Mini-Mental State Examination (MMSE) score <24 before surgery, (2)

Results

The clinical and demographic characteristics of the 61 patients and the comparison between CABG surgery with and without CPB are presented in Table 1. Both with and without CPB groups were comparable for each preoperative variable except for hypertension. The CABG surgery without CPB group showed a higher incidence of hypertension.

The majority of patients (n = 45) were recruited a day before surgery. The others were recruited at the preadmission clinic (n = 16) (ie, 27 ± 24 days before surgery),

Discussion

POCD after cardiac surgery is a frequently reported complication affecting patients' postoperative outcomes. The etiology of POCD can be multifactorial; the most commonly cited etiologies being embolism and hypoperfusion related to CPB, which affect the cerebral oxygen supply-demand balance.46 Among the neurologic monitoring techniques available to detect a cerebral oxygen supply-demand imbalance during cardiac surgery, NIRS allows the continuous and noninvasive monitoring of rSO2 and provides

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    Supported by the Montreal Heart Institute Foundation.

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