Final answer:
Defibrillation is used for ventricular fibrillation and pulseless ventricular tachycardia, both of which hinder the heart's ability to pump blood and present life-threatening emergencies.
Step-by-step explanation:
The dysrhythmias you would defibrillate are ventricular fibrillation and ventricular tachycardia without a pulse. In cases of ventricular fibrillation, the heart beats in an uncontrolled, rapid manner that inhibits its ability to pump blood, presenting a medical emergency. Immediate defibrillation is critical. Pulseless ventricular tachycardia, which is also life-threatening, requires defibrillation as the heart is not effectively pumping blood.
Atrial fibrillation and supraventricular tachycardia may require other interventions such as medication or electrical cardioversion but not immediate defibrillation. To clarify, atrial fibrillation is serious but not immediately life-threatening as long as the ventricles pump blood, while supraventricular tachycardia refers to arrhythmias that originate above the heart's ventricles. Sinus bradycardia is a slow heart rate and does not call for defibrillation. Treatment might involve pacing or drugs, but not defibrillation.
Therefore, the correct answer to the question - Which dysrhythmias would you defibrillate? - is (a) ventricular tachycardia, provided that there is no pulse, and dysrhythmias which are a type of ventricular arrhythmia.