Use of an inspiratory impedance threshold device on a facemask and endotracheal tube to reduce intrathoracic pressures during the decompression phase of active compression-decompression cardiopulmonary resuscitation

Introduction: Use of an inspiratory impedance threshold device (ITD) significantly increases coronary perfusion pressures and survival in patients ventilated with an endotracheal tube (ETT) during active compression‐decompression cardiopulmonary resuscitation. We tested the hypothesis that the ITD could lower intratracheal pressures when attached to either a facemask or ETT. Methods: An active and sham ITD were randomly applied first to a facemask and then to an ETT during active compression‐ decompression cardiopulmonary resuscitation in 13 out-of-hospital cardiac arrest patients in a randomized, double-blinded, prospective clinical trial. The compression-to‐bag-valve ventilation ratio was 15:2. Airway pressures (surrogate for intrathoracic pressure) were measured with a pressure transducer. A sham and an active ITD were used for 1 min each in a randomized order, first on a facemask and then on an ETT. Statistical analyses were made using Friedman’s and Wilcoxon’s rank-sum tests. Results: For the primary end point, mean SD maximum negative intrathoracic pressures (mm Hg) during the decompression phase of cardiopulmonary resuscitation were 1.0 0.73 mm Hg with a sham vs. 4.6 3.7 mm Hg with an active ITD on the facemask (p .003) and 1.3 1.3 mm Hg with a sham ITD vs. 7.3 4.5 mm Hg with an active ITD on an ETT (p .0009). Decompression phase airway pressures with the facemask and ETT were not statistically different. Conclusions: Use of an active ITD attached to a facemask or an ETT resulted in a significantly lower negative intratracheal pressure during the decompression phase of active compression‐ decompression cardiopulmonary resuscitation when compared with controls. Airway pressures with an ITD on either a facemask or ETT were similar. The ITD‐facemask combination was practical and enables rapid deployment of this life-saving technology. (Crit Care Med 2005; 33:990‐994)