code: function artery(pw, iv, meds) {
      if (!iv.artery) iv.artery = new Artery();
      plet.props(iv.artery, sprops, meds || iv, true);
      iv.artery.count = iv.count;
      iv.artery.data = iv.data;
      iv.artery.passes = iv.passes;
      iv.artery.pass = iv.pass;
      return iv.artery;
  }
docs: Generates an artery or sets properties an artery when the I.V. artery already exists
  
  @private
  @arg {PulseEmitter} pw the pulse emitter
  @arg {Array} iv the I.V. catheter
  @arg {Array} meds the pulse events
  @returns {Artery} the artery