Final answer:
For an adult with stable tachycardia and a regular, narrow-complex pulse, an initial IV adenosine dose is 6 mg, followed by a possible second dose of 12 mg if needed, with careful monitoring and under medical supervision.
Step-by-step explanation:
The initial intravenous dose of adenosine for an adult with stable tachycardia, showing a pulse with regular and narrow complexes, is generally 6 milligrams (mg) given rapidly over 1-2 seconds, followed by a normal saline flush. If the first dose is not effective, a second dose of 12 mg can be administered 1-2 minutes after the first dose. It's essential that this procedure is conducted with continuous cardiac monitoring and under the guidance of a medical professional experienced with advanced cardiac life support (ACLS).
Tachycardia is not normal in a resting patient and is defined as a heart rate (HR) above 100 beats per minute (bpm). It can lead to symptoms such as dizziness, shortness of breath, and fainting. Adenosine works by slowing the electrical conduction through the atrioventricular (AV) node, thus helping to restore normal heart rhythm.