Updated July 2026 · 9 min read
Part of the ICU Emergencies Hub — browse every related guide in one place.
A chest tube looks intimidating — a big bore catheter in the pleural space feeding into a plastic box of bubbling water — but the physics behind it is simple, and once you can read the drainage system you can tell at a glance whether your patient's lung is healing or heading for trouble.
The pleural space is normally a potential space under slight negative pressure that keeps the lung apposed to the chest wall. Anything that fills it — air (pneumothorax), blood (hemothorax), fluid (pleural effusion), pus (empyema), or post-operative drainage from cardiothoracic surgery — collapses the lung and can compress the heart and great vessels. The chest tube drains the offending material and re-establishes negative pressure so the lung re-inflates. Your job is to keep that one-way drainage working and to recognize when it isn't.
Modern disposable units (Pleur-evac and similar) combine three functional chambers into one box. Understand what each does and the whole thing stops being mysterious.
| Chamber | Job | What you watch for |
|---|---|---|
| Collection chamber | Collects drainage from the pleural space; graduated columns | Volume, color, rate of output — mark the level and time on the chamber each shift |
| Water seal chamber | One-way valve: lets air out of the chest, never back in (2 cm water) | Tidaling (fluid rises/falls with breathing) and air leak (bubbling) |
| Suction control chamber | Regulates the negative pressure applied (water column height or a dry dial, commonly −20 cmH2O) | Gentle continuous bubbling in a wet system, or the dial/float indicator in a dry system |
Tidaling is the normal rise and fall of the fluid level in the water-seal chamber with the patient's respiratory effort (it moves up with inspiration on a spontaneously breathing patient, and the opposite on a positive-pressure ventilated patient). Tidaling tells you the tube is patent and communicating with the pleural space. Loss of tidaling means either the lung has fully re-expanded (good) or the tube is obstructed/kinked/clotted (bad) — correlate with the patient, the chest x-ray, and output.
An air leak is bubbling in the water-seal chamber, and it means air is coming out of the pleural space (an ongoing pneumothorax or a bronchopleural communication) — or air is entering the system from a loose connection. Assess it by where it bubbles: continuous bubbling with every breath, or only on cough/exhalation.
A chest tube can drain to suction (active negative pressure, commonly −20 cmH2O) or to water seal / gravity (no wall suction, the water seal still acts as the one-way valve). Suction speeds evacuation of a large air or fluid burden; transitioning to water seal is often a step toward removal to see whether the lung stays up without help. Follow the provider's order — but know that the water seal always protects the patient even without suction, which is why you can safely disconnect wall suction to transport.
Two scenarios demand an immediate, memorized response.
Keep the drainage unit upright and below the level of the patient's chest so drainage flows down and nothing refluxes. Keep connections taped/banded and the tubing free of dependent loops and kinks (a loop full of fluid raises the pressure the patient must overcome to drain). Do not routinely strip or milk the tubing — it generates dangerously high negative pressures and is no longer recommended for most patients; gentle "fluttering" to move a visible clot may be acceptable per policy. And do not clamp a chest tube except for the specific, brief, ordered reasons (changing the unit, assessing for removal, or locating a leak) — never for transport of a patient with an air leak.
Escalate for a sudden increase in bright red drainage (>100–200 mL/hr, or per your surgeon's threshold, suggests active bleeding), a new or worsening air leak, sudden cessation of drainage with worsening respiratory status (possible obstruction with re-accumulation), subcutaneous emphysema (crepitus spreading up the chest/neck), or any signs of tension pneumothorax — rising airway pressures, hypotension, tachycardia, tracheal deviation, absent breath sounds. These are the moments the chest tube is telling you something the monitor hasn't yet.
Read the system, don't fear it. Confirm it's upright and below the chest, mark and trend the output, know whether you're seeing normal tidaling or an air leak and which way that leak is trending, and have the dislodgement and disconnection responses memorized before you need them. A chest tube is one of the few bedside devices where a knowledgeable nurse catches the deterioration before anyone else in the building.
This article is general educational information for licensed clinicians and students, not medical advice or a substitute for your institution's protocols or a provider's orders. Always follow facility policy.
Get The ICU Notebook Newsletter
Clinical tools and career insights for ICU nurses. One email per week, no fluff.
Yes, send it freeNo spam. Unsubscribe any time.