Masimo has announced the findings of a prospective study published in Frontiers in Neurology in which Na Xu and colleagues at Capital Medical University in Beijing, China investigated whether general anaesthesia guided by the company’s SedLine brain function monitoring parameters, and using its Root patient monitoring and connectivity platform, could reduce the incidence of postoperative delirium (POD) in patients undergoing carotid endarterectomy (CEA) procedures.
Through a combination of SedLine’s patient state index (PSi)—an index based on processed electroencephalogram (EEG)—and the density spectral array (DSA)—which represents the power of the EEG on both sides of the brain—to guide anaesthesia during the procedure, the researchers found a significantly reduced risk of POD. They further conclude that patients “may benefit from the monitoring of multiple EEG parameters during surgery”.
The researchers note that cerebral blood supply may be “severely disrupted” during CEA—the gold standard treatment for severe carotid stenosis—and that cerebral function is “highly vulnerable” to even brief changes in oxygen and blood supply, as well as to cerebral vascular diseases like carotid stenosis.
POD is an acute state of mental confusion characterised by alterations in attention and consciousness, and disorganised thinking. It is a common and serious geriatric neurological dysfunction, affecting up to 60% of patients after major surgery, according to a Masimo press release. It is also associated with worse short- and long-term prognoses, and higher healthcare costs, the release adds.
Noting that the incidence of POD is associated with the duration of EEG suppression during surgery, the researchers sought to investigate whether monitoring multiple processed EEG parameters simultaneously to guide anaesthesia during a procedure like CEA could positively impact the incidence of POD, compared to use of a single parameter alone, via a single-centre, prospective, randomised clinical trial.
They enrolled 255 patients scheduled for CEA and divided them randomly into an intervention group (n=127, mean age=62 years) and a standard group (n=128, mean age=63 years). In the intervention group, general anaesthesia was managed using a combination of SedLine PSi and DSA monitoring—designed to reduce the risk of intraoperative EEG burst suppression—and, in the standard group, PSi without DSA monitoring was used. In both groups, patients were also monitored with continuous transcranial Doppler ultrasound and near-infrared spectroscopy (NIRS) designed to avoid perioperative cerebral hypoperfusion or hyperperfusion.
The primary outcome was the incidence of POD, measured using the Confusion Assessment Method, during the first three days after surgery. Secondary outcomes were postoperative hospital length of stay and other neurologic complications. A team of neurophysiologists independently reviewed the EEG data acquired by SedLine to calculate the cumulative duration of burst suppression for each patient.
The researchers found that the incidence of POD was significantly lower in the intervention group (7.87% of patients) compared to the standard group (28.91% of patients, p<0.01). Patients in the intervention group also spent significantly less overall time with EEG suppression. In addition, there was no significant difference in the incidence of other neurologic complications.
“Processed electroencephalogram-guided general anaesthesia management, consisting of PSi combined with DSA monitoring, can significantly reduce the risk of postoperative delirium in patients undergoing CEA,” the researchers conclude. “Patients, especially those exhibiting haemodynamic fluctuations or receiving surgical procedures that disrupt cerebral perfusion, may benefit from the monitoring of multiple EEG parameters during surgery.”