Final answer:
For effective suction of mouth secretions, a 10Fr or larger suction catheter should be used. The correct size ensures both safety and effectiveness.
Step-by-step explanation:
To suction secretions from the mouth effectively, you should connect a 10Fr or larger suction catheter. The sizing of the catheter is important to ensure that the suction is strong enough to clear the mouth of secretions without causing harm to the patient. A suction catheter that is too small may not be effective, whereas one that is too large could cause discomfort or injury.