Vagal Maneuvers for Stable Tachycardia Patients
Vagal maneuvers are used for the treatment of stable patients in SVT. They’re called that because the principal action is stimulation of the vagus nerve. Remember that we give Atropine to unstable patients with bradycardia to block the vagus nerve and speed the heart up? Stimulating the vagus nerve of stable patients with tachycardia to slow the heart is today’s Pass ACLS tip topic.
Our first actions when identifying someone with tachycardia is to obtain a quick history, vital signs, & physical assessment to identify & address potential underlying causes. In addition to physical exertion & emotional stress, several acute medical conditions such as hypoxia, sepsis, and hypovolemia can cause tachycardia.
Initial management of tachycardic patients includes:
- Maintaining the patient’s airway;
- starting oxygen if the pulse ox is less than 90%;
- hooking up the ECG;
- starting an IV; and
- getting a 12 lead.
Patients with a heart rate over 150 with any of the following are unstable:
- hypotension;
- altered mental status;
- signs of shock or acute CHF; and
- a complaint of ischemic chest pain.
Patients with a heart rate over 150 and any of these are considered unstable and should be rapidly cardioverted with a synchronized shock after considering sedation.
The next steps in the tachycardia algorithm are dependent on whether the QRS is wider than 0.12 seconds, or three tiny boxes on a strip. This is a quick way to assess if the rhythm is SVT or a perfusing V-Tach without memorizing the Brugata criteria. If you’d like a review of the Brugata criteria used to differentiate V-Tach from SVT with an aberrant conduction, check out the “Brugada Criteria for V Tach” presented by Emergency Medical Minute podcast.
For the remainder of today’s topic, let’s assume we have a stable patient with a narrow complex SVT. After our initial steps, the first treatment action will be vagal maneuvers.
Simple vagal maneuvers include:
- asking the patient to cough;
- have the patient push hard like straining with a bowel movement;
- ask the patient to blow into the end of a needless syringe; or
- having the patient push with their legs elevated & knees bent.
If having the patient cough, or other actions that cause them to strain against a closed glottis, doesn’t work, then ice water could be splashed on their face.This stimulates the dive reflex which also slows the heart.
If the patient doesn’t have a history of arterial sclerosis, TIAs, or stroke, AND no bruits are heard while auscultating the carotid artery, carotid sinus massage can be done. Because of the risk of releasing a carotid emboli, some organizations restrict this procedure to physicians and mid-level providers.
Always follow your state laws & organization’s policies and only perform procedures that are within your scope of practice.
If vagal maneuvers are unsuccessful, consider administration of 6 mg of Adenosine rapid IV push followed by a 20 ml saline flush. If A-Fib or flutter is seen on the ECG after the first dose of Adenosine, consider the use of a calcium channel blocker or beta blocker medication. A review of Adenosine is covered in another Pass ACLS Tip of the Day episode.
