You and another provider are attending to a 17-year-old boy found unresponsive with occasional gasps. you are not certain if a pulse is present. what should you do

Those occasional gasps are called agonal breathing and the patient is clearly on comatose. Immediately call for help and perform basic life support (if you are certified) should be done by performing cardiopulmonary resuscitation by giving 30 chest compressions at around 100-120 beats per minute (in the rhythm of Staying Alive by Bee Gees) then followed by two rescue breaths. After which check for spontaneous breathing and pulses. If still unresponsive, continue performing CPR until help arrives. 

Called for cell.