During a procedure the bellows can and will move in either direction depending on cuff pressure changes. When the black marking on the bellows moves into the ‘yellow’ zone, this indicates a possible decrease in pressure or under inflation. Pressure measurements typically experienced in the ‘yellow’ zone range from 0cm water pressure through to 50cm water pressure.

The bellows moving in the opposite direction into the ‘red’ zone indicates a possible increase in the cuff pressure or over inflation. This indicates a pressure of +70cm water pressure and it is recommended that pressure be released until the black bellows marking moves back into the ‘green’ zone.