So, supposedly, impedance threshold devices installed inline for ventilation during CPR potentially improve hemodynamics via negative intrathoracic pressure. This is a prospective, randomized, multi-center, placebo-controlled sham study that really meets a very high standard for internal validity. Over 4000 patients in the ITD group, the sham ITD group, and the not-enrolled comparison cohort.
Short summary:
– Minimal differences between groups.
– 27.8% sham vs. 27.1% active device ROSC in the ED.
– 8.2% sham vs. 8.2% active device discharge from the hospital.
– No apparent harms from the ITD device, but no benefits either.
The most important point from this article is that we have gotten sloppy in our rush to implement supposedly new and beneficial therapies in medicine. Hypothermia, TPA for stroke, Factor VIIa, direct thrombin inhibitors, etc. and we should add impedance threshold devices to the list. The AHA has had ITD as a class IIa recommendation to improve hemodynamics since 2005 – six years of useless therapy and costs based solely on a theoretical model without proof of improved outcomes. Hammering this point home never gets old.
“A Trial of an Impedance Threshold Device in Out-of-Hospital Cardiac Arrest.”
www.ncbi.nlm.nih.gov/pubmed/21879897