Sampling of lung interstitial fluid in intact dog

Area of Science:

• Pulmonary Medicine
• Physiology
• Surgical Innovation

Background:

• Accurate measurement of lung interstitial fluid composition is crucial for understanding pulmonary edema and fluid dynamics.
• Previous methods for sampling lung interstitial fluid often require invasive procedures like thoracotomy.
• The peribronchial-perivascular space (PBVS) is a key compartment for lung interstitial fluid.

Purpose of the Study:

• To report a minimally invasive method for sampling fluid from the lung's peribronchial-perivascular space (PBVS) in intact chest dogs.
• To compare the colloid osmotic pressure (COP) of PBVS fluid with right lymph duct fluid (RLDF) under various physiological conditions.
• To assess the feasibility of this PBVS fluid sampling technique for potential human application.

Main Methods:

• A wick catheter was introduced into the PBVS via mediastinoscopy in dogs.
• Right lymph duct cannulation was performed for RLDF collection.
• Colloid osmotic pressure (COP) was measured in PBVS and RLDF following infusions of lactated Ringer's solution (LR) with or without left atrial balloon inflation (LRB) or oleic acid (LRO, LROB).

Main Results:

• Adequate fluid volumes for COP measurement from PBVS wicks were obtained, particularly in LRO and LROB groups.
• Protein content and fluid yield from PBVS were higher in LRO and LROB groups compared to LR and LRB.
• No significant differences in mean COP were observed between PBVS fluid and RLDF across experimental conditions.

Conclusions:

• Direct sampling of lung interstitial fluid from the PBVS is feasible in dogs without thoracotomy.
• The study confirms the high colloid osmotic pressure of fluid within the lung interstitium.
• The described PBVS fluid sampling method shows potential for clinical application in human patients undergoing mediastinoscopy.