Publication: Validity of bispectral index monitoring at infra-orbital position in reference to the standard frontal position
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Date
2022-05
Authors
Zaki, Aina Ahmad
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Abstract
Background: In certain surgery, the placement of frontal BIS is not always possible as it may give inaccurate readings due to the interference from operation site or patient’s position. This study aimed to validate the BIS values obtained from the alternative infra-orbital sensor position in relation to standard frontal area during total intravenous anaesthesia (TIVA). Methods: A total of 71 patients who underwent elective surgery under target-controlled infusion (TCI) propofol and remifentanil were recruited. Each patient had two BIS sensors placed at their forehead and infra-orbital. BIS values were obtained at six timepoints; during awake, loss of consciousness, post intubation, skin incision, every 30 minutes during maintenance of anaesthesia, emergence and extubation. Data from both BIS sensors were compared using Pearson’s correlation and intraclass correlation (ICC). Repeated measures analysis of variance (ANOVA) was used to determine the relationship between the two positions. Results: Pearson’s correlation analysis showed positive correlation (p<0.05) for both positions. Analysis of ICC revealed strong internal consistency across all timepoints with coefficient value of 0.794. According to repeated measures ANOVA, both positions showed consistent trend in BIS values (p <0.001) with no significant difference in the mean readings (p=0.809). The BIS readings at different timepoints were not affected by the position of the probe (p=0.173).Conclusion: The infra-orbital BIS is consistent with frontal BIS monitoring and it can be an alternative to monitor depth of anaesthesia during TIVA whenever the standard frontal position is impossible
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Keywords
alternative , bispectral index