Fig. 2
From: Usefulness of a stool to stabilize dental chairs for cardiopulmonary resuscitation (CPR)
The displacement of the point P on the lower surface of the backrest (vertically under the area for external cardiac compression) was fixed a vertical-measurement instrument. The instrument was attached a metal indicator. a, b Chest compression depth was measured by the measurement equipment (skill-reporter®). The equipment glow green when chest compression depth was 3.8 to 5.0 cm, and red when 5.1 to 6.0 cm (c)