The effect of different anaesthetic mask shapes on the anatomical dead space using infant, child and adult part-task trainers

Abstract

Dead space is the portion of tidal volume that does not participate in alveolar gas exchange. The purpose of this study was to compare the dead space contribution of differently shaped masks, of the same size, by measuring the volume of each mask. The study was conducted in the Clinical Simulation Unit of the School of Medicine, University of the Free State (UFS) using formed masks with inflatable polyvinylchloride (PVC) cuffs and rounded masks with non-inflatable PVC cuffs. The masks were placed on the faces of the infant, child and adult part-task trainers as well as on a flat surface. The cuffs of the formed masks were inflated to 5 cm water and 70 cm water. Masks were filled with water and the volume was measured. The volumes (ml) of the masks on the flat surface were significantly larger than those measured on the part-task trainers' faces. The volume of the rounded masks was greater than the volume of the formed masks. The amount of cuff inflation pressure (5 cm water vs. 70 cm water) did not lead to a significant change in mask volume: 102.3 ml (standard deviation [SD] 75.9) vs. 110.2 ml (SD 82.3), averaged for all sizes. Formed masks contribute less to anatomical dead space than rounded masks and are thus possibly the better choice. Cuff inflation pressure has insignificant influence on dead space volume.

Comparison of intra-oral mask and classic face mask in terms of ventilation success and practitioners’ work load assessments: a randomized crossover study

“…Improper seal between the CFM and the patient's face may occur because of beard, facial anatomical deformity, toothlessness and etc. Additionally facemasks somewhat increases dead space and may cause insufficiency of tidal volume 10 .…”

Comparison of intraoral mask and classic face mask in terms of ventilation success and practitioners' workload assessments: A randomised crossover study

“…Improper seal between the CFM and the patient's face may occur because of beard, facial anatomical deformity, toothlessness, etc. Additionally, facemasks somewhat increase dead space and may cause insufficiency of tidal volume 10 . Practitioners commonly grasp the CFM with the thumb and index fingers in the form of C and place the CFM on the face of the patient, while raising the mandible with the other fingers in the form of E letter although there are some alternative grips 11 (Figure 1).…”