Prolonged postoperative cerebral oxygen desaturation after cardiac surgery

Abstract

BACKGROUND Near-infrared spectroscopy (NIRS) is used routinely to monitor cerebral tissue oxygen saturation (SctO2) during cardiopulmonary bypass (CPB) but is rarely employed outside the operating room. Previous studies indicate that patients are at risk of postoperative cerebral oxygen desaturation after cardiac surgery. OBJECTIVES We aimed to assess perioperative and postoperative changes in NIRS-derived SctO2 in cardiac surgery patients. DESIGN Prospective observational study. SETTING The study was conducted in a tertiary referral university hospital in Australia from December 2017 to December 2018. PATIENTS We studied 34 adult patients (70.6% men) undergoing cardiac surgery requiring CPB and a reference group of 36 patients undergoing non-cardiac surgical procedures under general anaesthesia. MAIN OUTCOME MEASURES We measured SctO2 at baseline, during and after surgery, and then once daily until hospital discharge, for a maximum of 7 days. We used multivariate linear mixed-effects modelling to adjust for all relevant imbalances between the two groups. RESULTS In the cardiac surgery group, SctO2 was 63.7% [95% confidence interval (CI), 62.0 to 65.5] at baseline and 61.0% (95% CI, 59.1 to 62.9, P = 0.01) on arrival in the ICU. From day 2 to day 7 after cardiac surgery, SctO2 progressively declined. At hospital discharge, SctO2 was significantly lower than baseline, at 53.5% (95% CI, 51.8 to 55.2, P < 0.001). In the reference group, postoperative SctO2 was not significantly different from baseline. On multivariable analysis, cardiac surgery, peripheral vascular disease and time since the operation were associated with greater cerebral desaturation, whereas higher haemoglobin concentrations were associated with slightly better cerebral oxygenation. CONCLUSION After cardiac surgery on CPB, but not after non-cardiac surgery, most patients experience prolonged cerebral desaturation. Such postoperative desaturation remained unresolved 7 days after surgery. The underlying mechanisms and time to resolution of such cerebral desaturations require further investigation.

NIRS: a gadget or a must for critically ill patients?

“…A good example has been demonstrated in a recent study in post cardiac-surgical patients which showed a progressive postoperative decline in rSO2 from the day of surgery until day 7 with 97% of patients below baseline value at discharge. 9 A given value at one time point was not associated with clinical deterioration. Hence, it seems appropriate to set an alarm value on NIRS to look at the determinants of brain oxygenation in a dynamic manner.…”

Cerebral monitoring in surgical ICU patients

“…Notably, cerebral desaturations continue to occur during the postoperative ICU stay in a large subset of patients [38,39]. A recent study showed prolonged postoperative cerebral desaturation after cardiac surgery with cardiopulmonary bypass (CPB), but not after noncardiac surgery [40]. Therefore, there is a need and growing interest in extending the monitoring of ScO 2 to the postoperative phase, even though the evidence is still limited [41] and insufficient to recommend postoperative monitoring [37 ▪▪ ].…”