General note: when a PALS starts choking/coughing, if s/he is using BiPAP, it helps to make sure settings are ramped down to where there is no backup rate, cycle sensitivity, target volume and/or max IPAP reduced, etc. so air flow that is too much/out of sync, does not increase irritation.
Also, even for a tube, consider papaya or pineapple juice, lemonade, warm liquids.