vagal responses

Q: Nasogastric tube placement (select one)

A)  increases the vagal tone
B) decreases the vagal tone


Answer: A

Various bedside maneuvers can cause increased vagal responses and may have undesired effects. It include prolonged sinus pauses or even asystole, atrioventricular blocks, or hemodynamic instability. Induction of  atrial fibrillation has been reported too. Carotid sinus massage may lead to stroke or transient ischemia attack (TIA).

Some common vagal maneuvers include carotid sinus massage, valsalva maneuver, eyeball pressure, breath holding, rectal exam, coughing, deep respirations, gagging, vomiting, swallowing, nasogastric (NG) tube placement and trendelenburg position.

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References:

1. Yamakawa K, So EL, Rajendran PS, et al. Electrophysiological effects of right and left vagal nerve stimulation on the ventricular myocardium. Am J Physiol Heart Circ Physiol 2014; 307:H722.

2. Davies AJ, Kenny RA. Frequency of neurologic complications following carotid sinus massage. Am J Cardiol 1998; 81:1256.