Pulmonary edema was diagnosed according to medical history, clinical symptoms, signs and X-ray table

 Pulmonary edema was diagnosed according to medical history, clinical symptoms, signs and X-ray table

According to the medical history, clinical symptoms, signs and X-ray manifestations, the general clinical diagnosis is not difficult. However, there is still a lack of satisfactory and reliable methods for early quantitative diagnosis of pulmonary edema. The clinical symptoms and signs are used as the diagnostic basis, and the sensitivity is low. When the extravascular fluid of the lung increases by 60%, the abnormal signs appear clinically. X-ray examination showed abnormal shadow only when the lung water volume increased by more than 30%. CT and MRI are helpful in the quantitative diagnosis and differentiation of pulmonary congestion and pulmonary edema. Plasma colloidal osmotic pressure pulmonary capillary wedge pressure gradient, radionuclide scanning, indicator dilution method for the determination of extravascular fluid and chest electrical impedance are helpful for early diagnosis, but they have not been applied in clinic. Blood gas analysis is helpful to understand the imbalance severity of arterial oxygen partial pressure, carbon dioxide partial pressure and acid-base balance, and can be used as a follow-up index of dynamic changes.

1. Laboratory inspection

Including blood and urine routine, liver and kidney functions, cardiac Zymogram and electrolyte examination, so as to provide basis for the diagnosis of infection, hypoproteinemia, kidney disease and heart disease.

2. Arterial blood gas analysis

Oxygen partial pressure is mainly manifested as hypoxia in the early stage of the disease, and oxygen inhalation can significantly increase PaO2. In the early stage of the disease, the partial pressure of carbon dioxide is mainly low CO2, and in the later stage, there is high CO2, respiratory acidosis and metabolic acidosis.

3. X-ray examination

Alveolar edema is mainly manifested as acinar dense shadow, irregular fusion fuzzy shadow, diffuse distribution or limited to one side or one leaf, or outward expansion from both sides of hilar, and gradually fade into typical butterfly shadow. Sometimes accompanied by a small amount of pleural effusion. However, the above manifestations can only occur when the lung content increases by more than 30%.

4. Swan Ganz catheterization inspection

The pulmonary capillary wedge pressure (PCWP) measured by intravenous Swan Ganz catheterization at the bedside can clarify the pulmonary edema with increased pulmonary capillary pressure, but the height of PCWP is not necessarily consistent with the degree of pulmonary edema.

5. Other inspections

In the past, many extravascular water (EVLW) measurement methods, such as X-ray, thermal indicator dilution technique, soluble gas inhalation, transpulmonary electrical impedance, CT, magnetic resonance imaging, etc., were not sensitive to the early judgment of microvascular alveolar barrier injury in pulmonary edema. In recent years, the permeability of pulmonary vascular endothelium was evaluated by measuring the net flow of isotope labeled protein (commonly used 99mTc) through pulmonary capillary endothelium in vitro; The degree of lung injury can be judged earlier by measuring the clearance of isotopic small molecules (radioactive marker protein, 99mTc DTPA) by alveoli and evaluating the permeability of alveolar epithelium.