Immediate Rapid Saline Flush Required
After administering adenosine 0.1 mg/kg IV push, you must immediately follow with a rapid flush of 5 to 10 mL of normal saline. This is critical for adenosine efficacy due to its extremely short half-life.
Why the Saline Flush is Essential
Adenosine has an ultra-short half-life and requires rapid delivery to the central circulation to be effective. The immediate saline flush ensures the medication reaches the heart before it is metabolized. Multiple high-quality pediatric and adult guidelines consistently emphasize this critical step 1, 2, 3, 1.
Proper Administration Technique
The two-syringe technique is preferred:
- One syringe contains adenosine 0.1 mg/kg (maximum 6 mg for first dose)
- Second syringe contains 5-10 mL normal saline flush
- Administer adenosine as rapidly as possible
- Immediately follow with the rapid saline flush
- In older children, a larger flush up to 20 mL may be helpful 1
Use the most proximal IV site possible to minimize the distance to central circulation 1.
What Happens Next
After the flush, you should:
- Continue continuous ECG monitoring
- Have a defibrillator immediately available 1
- Wait 30 seconds to assess response
- If no AV block occurs and there is no response within 30 seconds, give double the initial dose (0.2 mg/kg, maximum 12 mg) followed by another immediate rapid saline flush 1, 3
Common Pitfalls to Avoid
- Do not administer vagal maneuvers after adenosine - these are performed before adenosine, not after
- Do not give a second dose immediately - wait 30 seconds to assess the first dose response
- Do not use slow administration - rapid push is essential for efficacy 1
- Do not skip the saline flush - this is the most common reason for adenosine failure
The adult guidelines similarly emphasize that adenosine must be given as a "rapid IV push followed by a 20 mL saline flush" 2, 4, with the flush being an integral part of proper administration technique 5.