In a patient with extrinsic midtracheal compression causing obstruction, what is the type of airflow at the site of obstruction in the trachea?

In a patient with extrinsic midtracheal compression causing obstruction, what is the type of airflow at the site of obstruction in the trachea?

• A. Laminar flow
• B. Orifice flow
• C. Undulant flow
• D. Stenotic flow

Answer: (B)

When air is forced through a narrowed airway, the flow at the constriction behaves like orifice flow. The extrinsic compression creates a small aperture in the tracheal lumen, so air must accelerate to pass through that opening. This causes a jet-like current with a drop in pressure across the constriction and potential turbulence, rather than smooth, uniform flow. Laminar flow describes smooth, orderly motion in a long, uniform tube at low Reynolds numbers; the abrupt narrowing disrupts this pattern, making laminar flow unlikely. Stenotic flow describes the presence of narrowing but not the specific pattern of flow through the narrow opening, and undulant flow implies oscillatory waves rather than the steady jet through a constricted orifice. Thus, the flow at the site of obstruction is best described as orifice flow.

When air is forced through a narrowed airway, the flow at the constriction behaves like orifice flow. The extrinsic compression creates a small aperture in the tracheal lumen, so air must accelerate to pass through that opening. This causes a jet-like current with a drop in pressure across the constriction and potential turbulence, rather than smooth, uniform flow.

Laminar flow describes smooth, orderly motion in a long, uniform tube at low Reynolds numbers; the abrupt narrowing disrupts this pattern, making laminar flow unlikely. Stenotic flow describes the presence of narrowing but not the specific pattern of flow through the narrow opening, and undulant flow implies oscillatory waves rather than the steady jet through a constricted orifice. Thus, the flow at the site of obstruction is best described as orifice flow.