All subjects who call 9-1-1 for difficulty breathing will have the potential to be enrolled in the study.

At each call, the paramedic will initially evaluate the patient clinically conducting a standard history and physical exam. The paramedic will then use the portable U/S machine to look for the presence of either unilateral or bilateral B-lines indicating possible pneumonia (in the case of unilateral B-lines) or pulmonary edema (in the case of bilateral B-lines). The paramedic will then document the presence or absence of B-lines for each lung on the prehospital study sheet. The paramedic will then use the U/S to evaluate for the presence of pleural effusions, lung sliding and pericardial effusion.

The paramedic will use the portable U/S machine to look for the presence of either unilateral/bilateral B-lines indicating possible pneumonia (unilateral B-lines) or pulmonary edema (bilateral B-lines). The paramedic will document the presence or absence of B-lines for each lung on the prehospital study sheet. The attending ED physician will be notified of the enrolled patient and, blinded to the paramedic's interpretation, will then conduct the same U/S study and document their findings and the final diagnosis of the patient using the patient's name, birthdate and MRN (Medical Record Number) on the ED study sheet. An U/S expert, blinded to the patient's diagnosis, the U/S operator, and confirmatory imaging, will review the recorded images obtained in the prehospital setting. The expert's interpretation of the images will be confirmed by a second expert for at least 15 % of the cases. The goal is 80% accuracy. The accuracy will be evaluated up to 12 months after the U/S is taken.

The paramedic will use the U/S to evaluate for the presence of pleural effusions, lung sliding and pericardial effusion. The attending ED physician will be notified of the enrolled patient and, without knowing the paramedic's interpretation, will then conduct the same U/S study and document his or her findings and the final diagnosis of the patient using the patient's name, birthdate and MRN on the ED study sheet. An U/S expert, blinded to the patient's diagnosis, the U/S operator, and confirmatory imaging, will review the recorded images obtained in the prehospital setting. The expert's interpretation of the images will be confirmed by a second expert for at least 15 % of the cases. The goal is 80% accuracy. The accuracy will be evaluated up to 12 months after the ultrasound has been taken.