Chest drainage: how the system works

A chest drainage system restores the negative pressure that holds the lung against the chest wall by letting air and fluid out of the pleural or mediastinal space while allowing nothing back in, so the nurse reads it as connected chambers that each report something different rather than as a container to be emptied — the collection chamber, whose drainage is never tipped out but marked on the outside against the time so that the rate, the colour and the consistency can be compared across the shift, with a sudden increase, a change to bright red blood, or a fall to nothing all reported rather than charted and left; the water seal, whose fluid rises and falls with the patient's breathing for as long as the tube is patent and open to the pleural space, so that fluctuation which has stopped means either a lung that has re-expanded or a tube that is kinked, clamped, looped below the patient or blocked, a distinction settled by assessing the patient's breathing and breath sounds and tracing the tubing rather than assumed to be recovery, and in which bubbling is air leaving the pleural space, expected and intermittent while a pneumothorax is resolving; and the suction control, where the amount of suction is set by the height of the water column or by the dial of a dry regulator and never by how far the wall flow is opened, so that gentle bubbling or the indicator showing means only that suction is operating and harder bubbling merely boils the water away — while the unit is kept upright and below the level of the patient's chest so that what has drained cannot run back, the tubing is kept free of kinks and dependent loops and is never stripped or milked to clear it, the dressing over the insertion site is kept intact and occlusive, and the patient is helped to sit up, breathe deeply, cough, use the incentive spirometer and walk with the unit carried upright and below the chest, because a drain is a reason to re-expand the lung rather than a reason to keep the patient still.