What is the Alveolocapillary membrane?

[ ăl-vē′ə-lō-kăp′ə-lĕr′ē ] n. A thin layer of tissue that mediates the exchange of gases between the alveoli and the blood in the pulmonary capillaries.

How does DLCO test work?

Diffusing capacity (DLCO) is most commonly measured using the single-breath technique. The patient takes a full inspiration of a gas mixture containing 0.3 percent carbon monoxide and 10 percent helium (the dilution of which provides an index of lung or “alveolar” volume).

What is DLCO used for?

The DLCO measures the ability of the lungs to transfer gas from inhaled air to the red blood cells in pulmonary capillaries. The DLCO test is convenient and easy for the patient to perform.

What does low DLCO indicate?

A low DLCO indicates one of the following: pulmonary interstitial thickening (diffuse parenchymal lung disease [DPLD]); a loss of vasculature, as seen in COPD; or pulmonary vascular disease (ie, chronic thromboembolic pulmonary hypertension [CTEPH] or idiopathic pulmonary arterial hypertension [IPAH])

What role does surfactant play in the respiratory system?

Function. The main functions of surfactant are as follows: (1) lowering surface tension at the air–liquid interface and thus preventing alveolar collapse at end-expiration, (2) interacting with and subsequent killing of pathogens or preventing their dissemination, and (3) modulating immune responses.

What is alveolar capillary membrane changes?

Impaired gas exchange occurs due to alveolar-capillary membrane changes, such as fluid shifts and fluid collection into interstitial space and alveoli. This leads to excess or deficit of oxygen at the alveolar capillary membrane with impaired carbon dioxide elimination.

Why is DLCO low in pulmonary hypertension?

In patients with PAH, the primary cause of a low DLCO is a reduction in the pulmonary capillary blood volume, whereas in patients with IPF- PH, disorder/thickening of the alveolar to capillary membrane reduces the DLCO.

How do I read my DLCO results?

Normal DLCO: >75% of predicted, up to 140% Mild: 60% to LLN (lower limit of normal) Moderate: 40% to 60% Severe: <40%

Why is DLCO decreased in pulmonary hypertension?

A reduced DLco in pulmonary arterial hypertension (PAH) may be the consequence of vascular remodeling and is related to proportionate reductions in alveolar–capillary membrane diffusing capacity and total pulmonary capillary blood volume available for gas exchange.

Why does DLCO increase in alveolar hemorrhage?

Increased Dlco is much less common but can be seen in patients with alveolar hemorrhage (hemoglobin in the airspace appears to make the uptake of CO very high) or polycythemia or during exercise (via recruitment of more pulmonary capillaries).

What causes a decrease in DLCO?

There are several conditions that can decrease the DLCO. These include cigarette smoking, emphysema, interstitial lung disease, anemia, decreased lung volume, heart failure, pulmonary vascular disease (pulmonary emboli and pulmonary hypertension), and others.

How does surfactant prevent lung collapse?

Surfactant is released from the lung cells and spreads across the tissue that surrounds alveoli. This substance lowers surface tension, which keeps the alveoli from collapsing after exhalation and makes breathing easy.

What is alveolocapillary membrane?

a thin layer of tissue that covers a surface, lines a cavity, or divides a space or organ. adj., adj mem´branous. alveolar-capillary membrane (alveolocapillary membrane) a thin tissue barrier through which gases are exchanged between the alveolar air and the blood in the pulmonary capillaries.

Does alveolar–capillary membrane function correlate with functional status and exercise capacity?

The pathophysiological basis for this remains unknown. The aim of this study was to partition DLco into its membrane conductance (D M) and capillary blood volume components (Vc) and to assess if alveolar–capillary membrane function correlated with functional status, exercise capacity, and pulmonary vascular resistance.

What is the marker for alveolar–capillary barrier damage in pulmonary capillaries?

D M may be a useful marker for the alveolar–capillary barrier damage induced by raised pulmonary capillary pressure.

What is the function of the alveolodental membrane?

alveolar-capillary membrane ( alveolocapillary membrane) a thin tissue barrier through which gases are exchanged between the alveolar air and the blood in the pulmonary capillaries. Called also blood-air barrier and blood-gas barrier. alveolodental membrane periodontium.