Answer: Thanks for your question. One of the conditions to administer NTG to a patient in pulmonary edema who has not received NTG previously is that the systolic blood pressure must be greater than 140mmHg. In the case you describe above, if the blood pressure falls below 140mmHg, then the patient does not qualify for NTG. Administration of NTG during the same patient contact does not constitute previous authorized use (plus it dropped their blood pressure already).