you have done things appropriately. This is a case management issue and i would agree that the doctor must have seen the pt. immediately. The patient is in impending respiratory failure probably secondary to CHF with Acute pulmonary edema.(Does the chest xray shows it?). At that time, giving of high dose lasix immediately might have a big impact on the succeeding management of this pt, together with biPAP. Your MD is well-informed enough that it will only take approx. 5-10 minutes of hypoxemia and you will developed encephalopathy, which might lead to irreversible coma. The patient should been admitted to critical care/Intensive care unit in the first place and aggressive monitoring and management should have been done earlier. If you think you are right, trust ur instinct and be assertive in a nice way. If not, always call your immediate supervisor and superior if this happens again. tnx