You release your cricoid pressure and move to start examining the patient.
'Hold on doc! - I'm not sure I'm in yet.' Stomach contents start regurgitating into the pharynx, obscuring the paramedics' view. Luckily the ambulance man has the presence of mind to reapply the cricoid presure, while handing the paramedic the suction apparatus. The tube is passed into the trachea & the patient is ventilating adequately.