A newborn exhibits a heart rate of 50/min and is limp after delivery. What intervention should be initiated?

In the scenario described, where a newborn exhibits a heart rate of 50 beats per minute and is limp, the most appropriate intervention is positive pressure ventilation. This is because a heart rate below 60 beats per minute in a newborn indicates a critical situation requiring immediate intervention. Positive pressure ventilation is necessary to assist in establishing effective breathing and improving oxygenation.

The use of positive pressure ventilation helps to inflate the lungs and can stimulate respiratory efforts, which is crucial when the newborn is both bradycardic and showing signs of not being responsive (limp). It also plays a vital role in enhancing pulmonary blood flow and can lead to an increase in heart rate if effective breaths are being delivered.

In contrast, while tactile stimulation and blow-by oxygen may be appropriate measures in less severe cases or when the heart rate is slightly decreased, they are not sufficient in this critical scenario where the newborn's heart rate is dangerously low. Chest compressions are indicated only when the heart rate remains below 60 beats per minute despite adequate ventilation, and after ensuring effective positive pressure ventilation is in place. Thus, initiating positive pressure ventilation is the correct and necessary first step in this urgent situation.