This system is based on the principle just described, but it has an additional chamber that serves as the second hydraulic gate and has a ventilation hole. This additional chamber serves as a safety valve in case of disconnection or breakdown of the pump when the system is in the closed state. The pressure gauge, located in this chamber, also allows you to monitor the level of negative pressure in the exudate collection chamber during normal system operation.
Argyle system with double hydraulic shutter. The system is based on the Pleur-evac system, but it has an additional camera that serves as the second hydraulic gate.
When assessing the patient’s condition during drainage, each time you should answer three questions:
1. Do air bubbles enter the chamber that serves as a hydraulic shutter?
2. Does drainage function?
3. What is detachable and what is its volume?
Admission of air bubbles in the chamber, which serves as a hydraulic shutter
If air bubbles enter through the hydraulic valve, this means that air enters the drain somewhere between the pleural cavity and the hydraulic valve. If aspiration is carried out without the use of a pump, the presence of air bubbles in the fluid that serves as a hydraulic shutter usually indicates a permanent air leakage from the lung into the pleural cavity. If during the initial examination of the fluid air bubbles are not visible, then you should ask the patient to cough and see if there are any bubbles in the fluid. When coughing, intrapleural pressure increases, and small air bubbles should flow into the fluid.
If aspiration is carried out with the help of a pump, a complete or partial disruption of contact between the patient and the chamber, which serves as a hydraulic pump, will be accompanied. by the entry of air bubbles through the liquid. For example, if the lid on the exudate collection canister is not tightly closed, under the action of negative pressure, air will flow into and out of the can, passing through the water seal as bubbles. Leaks in the system are detected by clamping the drainage in the place of its exit from the chest wall. If the entry of air bubbles does not stop, then a leak is observed in the aspiration system itself, and it should be carefully examined. If, when the drainage is compressed, the entry of air bubbles stops, this means that air comes from the pleural cavity.
The entry of air bubbles through the water does not necessarily indicate the existence of a connection between the lung and the pleural cavity. If the drain is not too deeply inserted into the pleural cavity, then one or more openings in the drainage tube may be located outside the pleural cavity. Undoubtedly, in this case, the air can flow into the drainage tube directly from the atmosphere. This possibility should be kept in mind when inspecting drainage. In some cases, especially in exhausted patients with poor tissue turgor, air can enter the pleural cavity at the site of the drainage. In such patients, an additional several stitches should be applied to ensure tightness.
The entry of air bubbles through the chamber that serves as the hydraulic shutter should not be confused with the entry of bubbles through the chamber that controls the suction. With proper system operation, air bubbles will always appear in this chamber.