Subjective Narcosis Assessment Scale: measuring the subjective experience of nitrogen narcosis

The interaction of subjective experiences and objective measures of neuropsychological performance during hyperbaric exposure has received less attention in the literature, in part due to the shortage of available and appropriately standardized measures.

This study aimed to describe the psychometric properties of a modified version of the Subjective High Assessment Scale when used in the hyperbaric context, by exploring internal reliability, factor structure, associations with psychological variables and simple cognitive delayed recall, and the effect of task focus on the recall of subjective experience.

Seventy qualified divers completed dry hyperbaric chamber dives to 607.95 kPa, and completed ratings of their subjective experiences. Some also completed a delayed recall task and psychological measures prior to their dives.

The scale displayed good internal consistency, with four meaningful factors emerging. It showed some significant but small associations with trait anxiety and transient mood states, and a small to moderate correlation with recall performance. There was no significant effect of task focus on self-report of subjective experiences.

The modified scale, renamed the Subjective Narcosis Assessment Scale here, has useful psychometric properties, and promising potential for future use.