ANSWER:

 DO NOT PANIC, BUT START COUGHING REPEATEDLY AND VERY VIGOROUSLY. A DEEP BREATH SHOULD BE TAKEN BEFORE EACH COUGH, THE COUGH MUST BE DEEP AND PROLONGED, AS WHEN PRODUCING SPUTUM FROM DEEP INSIDE THE CHEST. A BREATH AND A COUGH MUST BE REPEATED ABOUT EVERY TWO SECONDS WITHOUT LET-UP UNTIL HELP ARRIVES, OR UNTIL THE HEART IS FELT TO BE BEATING NORMALLY AGAIN.