Heart failure patients are at a heightened risk of developing pulmonary edema. For example, as left-side cardiac function deteriorates, left atrial pressure can increase and cause lung capillary hypertension. Hypertension can cause fluid to accumulate first in interstitial lung space and then in alveolar or lung airspace. In a worst case scenario, excessive or prolonged hypertension causes rupture of lung capillaries. Consequently, a need exists for techniques to monitor onset and degree of pulmonary edema. Various exemplary technologies presented herein aim to address this need and other needs.