Prospective pilot study of cerebral near infrared spectroscopy monitoring during pre-hospital anaesthesia

BackroundNear-infrared spectroscopy (NIRS) provides a non-invasive measure of cerebral tissue oxygenation. The literature on application of this method in pre-hospital setting is limited. The aims of this study were to determine the feasibility of cerebral NIRS during pre-hospital anaesthesia and to quantify the changes in front lobe regional oxygen saturation (rSO(2)) during the pre-hospital phase. MethodsNIRS monitoring (Nonin SenSmart X-100) of front lobe regional oxygen saturation (rSO2) was initiated before induction of anaesthesia in 31 adult patients and continued until hospital arrival. The median age of the patients was 55years (IQR [range] 43-63 [20-84]), and 20 (65%) of the patients were male. The indications for pre-hospital anaesthesia were neurological reasons (29%), intoxication (23%), traumatic brain injury (23%) and successful resuscitation from cardiac arrest (16%). ResultsThe NIRS monitoring was successful in 29 of 31 cases (94%; 95% CI: 78-99). One patient could not be monitored due to poor probe-skin contact, and 1 patient had poor contact with 1 hemisphere. Monitoring was performed for a total of 1335minutes and was successful in both hemispheres 95% (95% CI: 94-96) of the time. The median lowest rSO(2) was 8% (IQR [range] 2-13 [0-30]) below baseline, and median peak rSO(2) was 7% (IQR [range] 2-11 [0-34]) above the baseline. Changes in rSO(2) without accompanying changes in vital signs were observed. ConclusionNIRS is feasible during pre-hospital anaesthesia and substantial changes were observed in some patients. It provides data beyond the standard monitoring used in the pre-hospital setting.