Use of the Bispectral Index to Predict Eye Position of Children during General Anesthesia

Abstract

PurposeTo assess the relationship between eye position and anesthesia depth using the bispectral index (BIS) value, a parameter derived from electroencephalography data.MethodsWe investigated the relationship between BIS value and eye position in 32 children who underwent surgery for epiblepharon under general anesthesia. BIS values were recorded continuously throughout the procedure (from induction to awakening). Eye positions were video-recorded and analyzed after surgery. The vertical position of each eye was scored according to its height in relation to the medial canthus. An eye position in which the upper eyelid covered one-third of the cornea was defined as a significant ocular elevation.ResultsThe BIS value correlated inversely with the end-tidal concentration of each anesthetic agent, whereas it correlated positively with the eye elevation score (eye position = 0.014 × BIS + 0.699, p = 0.011). The mean eye position score was significantly greater in patients whose BIS values were over 65. Eleven patients (34.4%) had significant ocular elevation; their mean concurrent BIS value was 61.6. Two of these patients had elevation during surgery and 9 had elevation during emergence from anesthesia.ConclusionsWe found that high BIS values were correlated with low levels of anesthetic concentration and high eye position, suggesting that BIS monitoring may be useful for predicting eye position during anesthesia. Particular attention must be given to eye position during ophthalmic surgery. Anesthesia depth can be maintained by assuring that the BIS value remains below 65.

Tonic Downward Movement of Eyes and Its Eccentric Positioning in Downgaze Under General Anaesthesia 

“…Though few studies have described up-gaze eccentric eye-positioning under general anesthesia, there is paucity in literature regarding eccentric down positioning of eyes. 4,5,6,14 Few of the studies describing eye positioning under general anesthesia encountered down positioning of eyes. 4,6,14 Power et al in his study observed nal eye position in downward direcion under different depths of general anesthesia 14 in few patients but their number, depth of general anaesthesia, and down-scoring of eye position were never described.…”

“…Most authors have described eccentric positioning of eyes under GA in upgaze. 4,5,6,12 Power et al while studying the depth of anaesthesia in young adults via sevo urane induction compared eye signs with EEG polysomnography and showed that, the deepest level of sleep was reached on an average 3 minutes before the onset of eccentric ocular positioning thereby suggesting that eccentric eye movements may occur even when a patient appears satisfactorily anesthetized. 14 Rossiter reported an incidence of 8% which increased up-to 18% without the use of muscle relaxants.…”

“…Many authors have described slightly divergent and elevated eye positions during general anaesthesia. 1,2,3,4 But only a few studies have described xed eccentrically deviated eye positions during ocular surgery under general anesthesia and discussed its de nite relationship with anesthetic depth. 4,5,6 A quantitative examination of the relationship between eye elevation and anesthesia depth has found the shallower level of anesthesia to be related to a higher eye position.…”

“…1,2,3,4 But only a few studies have described xed eccentrically deviated eye positions during ocular surgery under general anesthesia and discussed its de nite relationship with anesthetic depth. 4,5,6 A quantitative examination of the relationship between eye elevation and anesthesia depth has found the shallower level of anesthesia to be related to a higher eye position. 4,5,6 Deeper level of anesthesia-related to downward-position of eyes have been mentioned by few authors 4,6 but there is paucity in the literature about detailed description and documentation of abrupt eccentric downward movement of eyes or eccentric down-positioning of eyes during ophthalmic surgery under general anaesthesia (GA).…”

Automatic Positioning and Recognition of Anesthesia Points Based on Ultrasound Image Guidance Technology

“…The positioning principle is shown in Fig. 1 [17]. The left and right signal receivers are horizontally placed at the upper left and upper right of the positioning area, and the coordinate positions of the two signal receivers are known, and the distance d between the receivers can be measured or calculated.…”