EBM – Evidence vs Evident

Vandaag onderstaande lange maar interessante presentatie ‘Time to abandon evidence based medicine?’‘ van David Healy uit 2012 gekeken op YouTube. Hij illustreert op een heldere en overtuigende manier een aantal grote zwakten in ons huidige EBM stelsel en toont hoe wij structureel om de tuin geleid worden. Ik adviseer iedere arts (i.o.) een keer het benodigde uur de tijd te nemen […]

ECG of the Week – 13th June 2016 – Interpretation

The following ECG is from a 52yr old male presenting with dysponea.




Click to enlarge
Rate:
  • 96 bpm

Rhythm:

  • Regular
  • P waves difficult to see but likely present
    • Best appreciated in leads I & II

Axis:

  • RAD

Intervals:

  • PR – Unable to adequately identify P wave morphology to measure, suugestion of pr prolongation in lateral leads
  • QRS – Normal (100ms)

Additional:

  • High frequency artefact in all leads
  • Maximal in precordial leads
  • Relative sparring of leads I & aVL 

Interpretation:

  • Significant artefact obscuring the baseline and majority of ECG segments
  • Likely electrical interference from power supply (50Hz AC)
  • Need to check correct line frequency filter, electrode contact and remove obvious potential interfering devices from patient / area


What are the causes of ECG artefact ?

There are multiple causes of ECG artefact and they may relate to the patient, environment or equipment. They include:

  • Patient Factors
    • Implanted devices
    • PPM – Pacing Spikes
    • Nerve stimulators
    • Movement disorders e.g. Parkinson’s, essential tremor
    • Rigors
    • Muscle tremor / activity can be related to pain, hypothermia etc.
    • CPR
    • Transport artefact e.g. vehicle movement
  • Environmental
    • Interference from surrounding electronic devices. Relatively rare using newer ECG machines and environmental interferece if usually compounded by incorrect machine filter settings.
  • Equipment
    • Poor lead contact 
    • Damaged cable / connector
    • Filter settings including monitor vs filter mode and main supply hertz filtering



References / Further Reading

Life in the Fast Lane

ECGpedia

    Textbook

    • Chan TC, Brady WJ, Harrigan RA, Ornato JP, Rosen P. ECG in Emergency Medicine and Acute Care. Elsevier Mosby 2005.