When performing CPR as a single person, it is important that you establish a good seal with the mask while also supporting the mandible to keep the airway open. By using the E-C seal technique, you can ensure that the ambu / resuscitation mask is able to deliver life-saving oxygen to the person. To do this, you make a "C" shape with the index finger at the bottom of the mask, and the thumb at the top of the mask. This supports it and helps seal it. You then use the remaining fingers to su