Flexible fluid guide unit with high buckling stability

A process comprising the steps of:

• providing a ventilation arrangement for artificial ventilation of a patient, the ventilation arrangement comprising a ventilator, a patient-side coupling unit and a fluid guide unit;
• providing the fluid guide unit so as to comprise:
• an inner tube extending along a longitudinal axis and configured to guide a fluid, the inner tube having an inner tube Shore hardness;
• an outer tube having an outer tube Shore hardness;
• a spiral coil between the inner tube and the outer tube, wherein the spiral coil extends around the inner tube and is mechanically connected to both the inner tube and the outer tube, wherein the outer tube surrounds the inner tube and the spiral coil, wherein an outer surface of the outer tube is in thermal contact with an environment of the fluid guide unit and the outer surface of the outer tube is smaller than a sum of an outer surface of the spiral coil and a part of an outer surface of the inner tube which is not covered by the spiral coil, wherein the spiral coil has a spiral coil Shore hardness and wherein the spiral coil Shore hardness, measured in shoreA, is at least as high as the inner tube Shore hardness and at least as high as the outer tube Shore hardness;
• and a heating element configured to heat a fluid guided by the inner tube,
• wherein the spiral coil Shore hardness is at least 10 shoreA greater than the inner tube Shore hardness and the spiral coil Shore hardness is at least 10 shoreA greater than the outer tube Shore hardness, or
• wherein the spiral coil is a hollow spiral coil and has a spiral coil wall which surrounds a spiral-shaped cavity and the spiral coil wall has a wall thickness which is at least twice as great as a wall thickness of the inner tube and at least twice as great as a wall thickness of the outer tube, or
• wherein the spiral coil has the shape of a filled rod formed into a spiral, and a maximum dimension of the filled rod in a direction parallel to the longitudinal axis of the inner tube is at least four times as great as the wall thickness of the inner tube and at least four times as great as the wall thickness of the outer tube.

A ventilation arrangement for artificial ventilation of a patient, wherein the ventilation arrangement comprises:

• a ventilator configured to expel a breathable gas mixture;
• a patient-side coupling unit configured to be arranged in and/or on the body of a patient;
• and
• a flexible fluid guide unit, wherein the ventilation arrangement is configured to guide a breathable gas mixture expelled by the ventilator through the fluid guide unit to the patient-side coupling unit, and wherein the entire fluid guide unit or at least one segment of the fluid guide unit is configured so as to comprise:
• an inner tube extending along a longitudinal axis and configured to guide a fluid, the inner tube having an inner tube Shore hardness;
• an outer tube having an outer tube Shore hardness;
• a spiral coil between the inner tube and the outer tube, wherein the spiral coil extends around the inner tube and is mechanically connected to both the inner tube and the outer tube, wherein the outer tube surrounds the inner tube and the spiral coil, wherein an outer surface of the outer tube is in thermal contact with an environment of the fluid guide unit and the outer surface of the outer tube is smaller than a sum of an outer surface of the spiral coil and a part of an outer surface of the inner tube which is not covered by the spiral coil, wherein the spiral coil has a spiral coil Shore hardness and wherein the spiral coil Shore hardness measured in shoreA, is at least as high as the inner tube Shore hardness and at least as high as the outer tube Shore hardness;
• and a heating element configured to heat the fluid guided by the inner tube,
• wherein the spiral coil Shore hardness is at least 10 shoreA greater than the inner tube Shore hardness and the spiral coil Shore hardness is at least 10 shoreA greater than the outer tube Shore hardness, or
• wherein the spiral coil is a hollow spiral coil and has a spiral coil wall which surrounds a spiral-shaped cavity and the spiral coil wall has a wall thickness which is at least twice as great as a wall thickness of the inner tube and at least twice as great as a wall thickness of the outer tube, or
• wherein the spiral coil has the shape of a filled rod formed into a spiral, and a maximum dimension of the filled rod in a direction parallel to the longitudinal axis of the inner tube is at least four times as great as the wall thickness of the inner tube and at least four times as great as the wall thickness of the outer tube.