You’re sitting in resus bemoaning the departure of your most beloved attending when suddenly a patient wheels in without warning. The patient looks relatively stable but the triage RN tells you her heart rate was in the 150s — no time for a full set of vitals or an EKG. You adeptly obtain these; the patient is normotensive, but the EKG is a little hard to make out. Is it SVT? Sinus tach? Afib? Are those P waves? Flutter waves? You squint knowingly with your attending but neither of you feel certain.

Enter this neat trick: increase the paper speed on the EKG machine to help differentiate between these tachycardias. Our EKG machines are set to 25mm/sec, the standard paper speed. On the bottom of the monitor, select “More” on the far right; then select “25mm/s” along the bottom (the speed setting), which will bring up a menu of speed options. Select 50mm/s to double the length that the paper moves per second, effectively slowing down/stretching out your readout (as seen below where flutter waves become more apparent). This won’t truly reveal hidden rhythms in your EKG, but it may make them easier to see.

Thanks to Drs. Haji, Chen and Sethi for the inspiration behind this pearl.

Image: ECG Rate Interpretation. Life in the Fastlane. Accessed at