Cerebral oximetry in adult cardiac surgery to reduce the incidence of neurological impairment and hospital length-of-stay: A prospective, randomized, controlled trial

Abstract

Background Cerebral oximetry using near-infrared spectroscopy (NIRS) has been shown to reduce neurological dysfunction and hospital length-of-stay after adult cardiac surgery in some but not all studies. We audited maintaining cerebral saturations at or above baseline and showed improved neurological and length-of-stay outcomes. Our hypothesis for this study was that our NIRS protocol would improve neurological and length-of-stay outcomes. Methods This prospective, single centre, double-blinded controlled study randomized 182 consecutive patients, scheduled for cardiac surgery using cardiopulmonary bypass. Participants were randomized by concealed envelope prior to anaesthesia. NIRS study group were managed perioperatively using our NIRS protocol of 8 interventions, increase cardiac output, normocapnia, increase mean arterial pressure, increase inspired oxygen, depth of anaesthesia, blood transfusion, correction of bypass cannula, change of surgical plan to restore levels equal to or above baseline. The control group had standard management without NIRS. Primary outcomes were neurological impairment (early and late) and hospital length-of-stay. Secondary outcomes were ventilation times, intensive care length-of-stay, major organ dysfunction and mortality. Results 91 patients entered each group. There was a significant improvement in self-reported six-month general functionality in the NIRS group ( p = 0.016). Early neurological dysfunction and hospital length-of-stay was the same in both groups. Of the secondary outcomes only Intensive Care length-of-stay was statistically significant, being shorter in the NIRS group ( p = 0.026). Conclusion Maintaining cerebral saturations above baseline reduces time spent in Intensive Care and may improve long term functional recovery but not stroke, major organ dysfunction and mortality.

Cerebral oximetry in adult cardiac surgery: A closer look at outcomes

“…2 This prior finding suggests that Bennett et al's power calculations were based on a magnitude of clinical benefit that they were highly unlikely to observe. 1 Furthermore, we suggest that a less ambitious improvement would have more appropriately met the criteria of 'minimal clinically important difference'. 3,4 A significant difference in self-reported function at 6 months was found by Bennett et al 1 Although several validated measures incorporating functional status exist, 5 their study used what appears to be a newly created scale.…”

“…It is unclear how this scale handles these issues, and the authors do not explain the design or justify the use of this questionnaire in their study design, or comment on its reliability or validity. 1,4 The full potential of cerebral oximetry in cardiac surgery remains to be determined. Whilst there are sound theoretical foundations for its use, its potential benefits have not yet been shown to translate into practice.…”

Outcomes in Cardiac Surgery Based on Preoperative, Mean Intraoperative and Stratified Cerebral Oximetry Values

“…During the CPB and surgery, for all patients, as standard practice, a protocol was used to keep the rSO2 value at or above baseline using standard interventions shown in Table 1. The techniques used to maintain rSO2 were based on a protocol validated in an earlier study [8]. The software allowed us to calculate the mean preoperative rSO2, the mean rSO2 for the whole case, and time spent at the four decremental levels of ischemic exposure as in Table 2.…”

“…During the CPB and surgery, for all patients, as standard practice, a protocol was used to keep the rSO2 value at or above baseline using standard interventions shown in Table 1 . The techniques used to maintain rSO2 were based on a protocol validated in an earlier study [ 8 ].…”

“…However, some studies have shown better outcomes using NIRS [3,7]. One of the more consistent findings using cerebral oximetry is a reduction in intensive care and hospital LOS [7,8]. During CPB, there is no other non-invasive way to directly monitor cerebral oxygenation or any other major organ oxygenation.…”