Cerebral oxygen saturation monitoring during spinal neurosurgery in prone position using near infrared spectroscopy (NIRS)

Murniece S.1,2, Skudre A.1,2, Stepanovs J.1,2,Vjugins J.1,,Vanags I.2,Mamaja B.1,2
1Riga East University Hospital, Latvia 
2Riga Stradins University



BACKGROUND

•	NIRS can prevent postoperative complications like cognitive dysfunction, and organ failure.
•	The goal of the study was to determine whether prone position during spinal neurosurgery impacts cerebral oxygen saturation using NIRS. 

METHODS

•	28 patients (mean age 56y) were scheduled for spinal surgery in prone position (transpedicular fixation(TPF)=15, microdiscectomy(MDE)=8, spinal tumor removal(spinal Tu)=4, laminectomia=1).
•	Cerebral oxygen saturation (rScO2) was continuously monitored using INVOS 4100. 
•	We also assessed blood loss, postoperative complications (stroke, organ dysfunction, wound infection, days spent in ICU) and cognitive dysfunction. 
•	Anesthesia methods: induction with fentanyl 0.1–0.2mg, propofol 1-2mg/kg, atracurium 0.5mg/kg; maintenance - fentanyl 0.03–0.06μg/kg/min, atracurium 0.3–0.6mg/kg/h, sevoflurane to MAC 0.7–1.0, FiO2 0.5. 
•	All patients were extubated in the operating room. 

RESULTS

•	Significant changes in calculated mean rScO2 values between supine and prone position during the surgery were not observed (Figure 1).
•	Mean rScO2 during the whole surgery was 73% for the right side (R), 73% for the left side (L). Lying supine during induction R72%, L71%,  in prone position R74%, L74%,  returning back to spinal position R73%, L73%. 
•	11 out of 28 patients showed a slight to significant decrease in rScO2 values in prone position.
•	One patient with intraoperative blood loss (2000ml) showed a rScO2 decrease by 27% from baseline value (from rScO2 85% to 58% in prone position). 
•	One patient with stroke in anamnesis showed initial values before induction of anaesthesia 21% lower than average rScO2 (57% compared to average rScO2 72%). 
•	Average blood loss was 308ml (TPF=400ml; MDE=175ml; spinal Tu=200ml). 
•	Average duration of operation was 110min (TPF=112min; MDE=125min; spinal Tu=126min).
•	No incidence of stroke, organ dysfunction was observed. One patient was admitted to ICU due to blood loss.

CONCLUSION

Our first experience revealed, that the mean intraoperative cerebral oxygen saturation changes, during spinal neurosurgery, were not significant. 
11 out of 28 patients showed a mild to moderate decrease in cerebral oxygen saturation in prone position.