D) Patient with history of heart transplant
Adenosine acts at the SA and AV nodes to cause a brief block. Adenosine dosing for SVT is 0.1 mg/kg (max 6 mg) for the first dose, and 0.2 mg/kg (max 12 mg) for the second. There is some evidence, though, that success rates are significantly higher by going straight to the larger dose, with little downside. In particular, infants tend to be more refractory to the effects of adenosine on the AV node, and often require a higher mg/kg dose, or do not respond at all. Heart transplant patients, however, have parasympathetic denervation, increasing the sensitivity of the SA and AV node receptors. It was once thought to be unsafe to use adenosine at any dose for heart transplant patients, but very low doses are okay to use. Also, patients taking carbamazepine may have potentiated effects of adenosine; a lower dose should be used with these patients as well. Adenosine is safe in WPW patients who are NOT in A-fib, ie have a regular narrow complex supraventricular tachycardia. Adenosine is best given from an IV access point closest to the heart and followed with a rapid flush because it is metabolized very rapidly. Peds EM Morsels has a great article on adenosine dosing at http://pedemmorsels.com/adenosine-dose/
Loading ...
August 14, 2018 at 3:25 pm
D) Patient with history of heart transplant
Adenosine acts at the SA and AV nodes to cause a brief block. Adenosine dosing for SVT is 0.1 mg/kg (max 6 mg) for the first dose, and 0.2 mg/kg (max 12 mg) for the second. There is some evidence, though, that success rates are significantly higher by going straight to the larger dose, with little downside. In particular, infants tend to be more refractory to the effects of adenosine on the AV node, and often require a higher mg/kg dose, or do not respond at all. Heart transplant patients, however, have parasympathetic denervation, increasing the sensitivity of the SA and AV node receptors. It was once thought to be unsafe to use adenosine at any dose for heart transplant patients, but very low doses are okay to use. Also, patients taking carbamazepine may have potentiated effects of adenosine; a lower dose should be used with these patients as well. Adenosine is safe in WPW patients who are NOT in A-fib, ie have a regular narrow complex supraventricular tachycardia. Adenosine is best given from an IV access point closest to the heart and followed with a rapid flush because it is metabolized very rapidly. Peds EM Morsels has a great article on adenosine dosing at http://pedemmorsels.com/adenosine-dose/