Table 1.

Ordinal scale used to assign an interference score to each observed distraction.

Interference level	Observable effect on team member or team functioning
1.	Potentially distracting sources (e.g., beeper call but no one responds to it)
2.	Interference noticed by floating personnel (e.g., beeper call is noticed by the circulating nurses but not dealt with)
3.	Floating member attends to noncase distraction (e.g., the circulating nurse responds to the beeper call)
4.	Single team member momentarily distracted from the task (e.g., anaesthesiologist orients away from the focal tasks of documentation to a beeper call while continuing with the documentation)
5.	Team member pauses current task
6.	Team member attends to distraction (e.g., surgeon responds to queries about the next case)
7.	Team distracted momentarily
8.	Team attends to distraction
9.	Operation flow disrupted (e.g., equipment failure that stops the surgical procedure)