Chest Tubes and Pneumothorax

In depth

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Pleural physiology and pressures

The pleural space is a film 10–20 µm wide holding about 0.26 mL/kg of fluid in total (Noppen 2000). Fluid filters from parietal pleural capillaries and drains through parietal lymphatic stomata, mostly over the diaphragm, turning over about 0.15 mL/kg/h; lymph flow can rise to roughly 30 mL/h before an effusion accumulates (Miserocchi 1997).

Lung recoil and chest wall spring keep pleural pressure subatmospheric: about −5 cm H₂O at functional residual capacity and −8 at the end of a quiet breath in (West). When air or fluid enters, the lung recoils toward its unstressed volume; the swings below are what the drain shows.

Hypoxic vasoconstriction limits the fall in PaO₂, so a young patient may keep a normal SpO₂ with a large primary pneumothorax while a small one can decompensate COPD. Breathlessness from a large effusion tracks diaphragm mechanics more than oxygenation: in PLEASE (Muruganandan 2020), drainage relieved it in 73% with no change in oxygenation, and a flattened or inverted hemidiaphragm predicted relief.

Pneumothorax: types, tension physiology and BTS 2023

Primary spontaneous pneumothorax occurs without known lung disease; secondary pneumothorax complicates COPD, cystic fibrosis, interstitial disease or necrotizing infection. Recurrence follows about 32% of first primary and 13–39% of first secondary episodes (BTS 2023).

BTS 2023 no longer uses size to decide whether to intervene, only whether a procedure is safe (generally 2 cm or more on CXR). High-risk patients get a chest drain if one can be placed safely: hemodynamic compromise, significant hypoxia, bilateral pneumothorax, underlying lung disease, age 50 or more with significant smoking, or hemopneumothorax. Others choose conservative care (minimal symptoms, any size), an ambulatory valve device, or needle aspiration or a drain. In the PSP trial (Brown 2020, 316 patients), conservative care re-expanded 94.4% by 8 weeks vs 98.5%, non-inferior only in the complete-case analysis, with fewer recurrences. RAMPP (Hallifax 2020, 236 patients) cut median stay from 4 days to 0 with an ambulatory device but raised adverse events (55% vs 39%).

Tension develops when a one-way leak adds air with each breath: pleural pressure stays positive, the mediastinum shifts and venous return falls, an obstructive shock. In Roberts 2015 (Ann Surg, 183 cases), ventilated patients had 12.6 times the odds of hypotension and 17.7 times the odds of arrest, usually within minutes; spontaneously breathing patients showed hypoxia and distress first. Tracheal deviation is late. On the ventilator, peak and plateau pressures rise (volume modes) or tidal volume falls (pressure modes), with falling SpO₂, EtCO₂ and blood pressure.

ATLS decompresses adults at the 4th or 5th space just anterior to the mid-axillary line (since the 10th edition), and ATLS 11 makes finger and tube thoracostomy the mandatory skills with the needle optional; 5 cm catheters fail in 38% at the 2nd space mid-clavicular vs 13% at the anterior axillary line (Laan 2016), hence the shift to 8 cm catheters. A tube must follow. Finger thoracostomy works on a ventilator but becomes an open pneumothorax in a spontaneously breathing patient. Occult traumatic pneumothoraces can be watched during brief ventilation; 40% of those ventilated over 5 days needed a drain (OPTICC 2021).

Hemothorax, effusions and pleural infection

A hemothorax has a pleural hematocrit at least half the blood value. Intercostal and internal mammary arteries bleed at systemic pressure; lung parenchyma bleeds at low pressure and usually stops once the lung re-expands. ATLS calls over 1,500 mL (or a third of blood volume) massive: 1,500 mL on insertion, about 200 mL/h for 2–4 hours, or ongoing transfusion points to thoracotomy, judged with physiology. Falling output in a patient still bleeding may be clot, not hemostasis.

28–32 F tubes drained as well as 36–40 F (Inaba 2012), ATLS 11 skill stations use a 28 F tube, and in stable patients 14 F catheters failed as often as 28–32 F tubes (11% vs 13%, Kulvatunyou 2021 RCT). Retained hemothorax follows about 29% of tube drainage (EAST 2020); EAST 2021 favors early VATS, within 4 days, over fibrinolytics.

Light's criteria (BTS 2023) define an exudate by any of: pleural/serum protein >0.5, pleural/serum LDH >0.6, or pleural LDH >two-thirds of the serum upper limit. They mislabel about a quarter of transudates, mostly diuresed heart failure; an albumin gradient above 1.2 g/dL or a raised NT-proBNP points to a transudate.

Measure pH at once in a blood-gas analyzer: heparin or lidocaine in the syringe lowers it, delay and air raise it. BTS 2023 drains pleural infection with tubes of 14 F or less, flushed with about 30 mL saline every 6–8 hours, plus antibiotics and nutrition. Up to 20% die within a year; the RAPID score (urea, age, purulence, infection source, albumin) stratifies risk.

MIST2 (Rahman 2011, NEJM, 210 patients) gave tPA plus DNase for 3 days: pleural opacity fell 29.5% vs 17.2%, surgical referral fell from 16% to 4% and stay shortened by 6.7 days, while either drug alone failed. BTS 2023 suggests the combination when drainage stops with a residual collection, rejects streptokinase (MIST1) and single agents, and allows 5 mg tPA when bleeding risk is higher.

1. Check position and patency; consent covers bleeding; exclude recent stroke, major bleeding or trauma, and surgery within 5 days.
2. Instil alteplase 10 mg in 30 mL saline, then DNase 5 mg in 30 mL, then a saline flush; close the drain for 1 hour; repeat twice daily for 3 days (BTS 2023).

The drainage system: physics, suction and air leaks

Each unit is three bottles in one. The collection chamber holds fluid. The water seal is a tube about 2 cm under water: without suction, air leaves whenever pleural pressure exceeds about +2 cm H₂O and cannot return, because inspiration only draws water up the tube, so the column works as a manometer. In a wet suction chamber, wall suction pulls room air through a vent tube submerged to the set depth, usually 20 cm, so water depth, not the wall gauge, limits suction (the pleura sees about −18 cm H₂O); turning up the wall only bubbles harder and evaporates water.

A fluid-filled dependent loop adds back-pressure equal to its height in cm H₂O and can stop drainage.

BTS 2023 advises against routine suction and against suction soon after insertion (re-expansion edema); if used, it is prescribed, high volume and low pressure, −10 to −20 cm H₂O. Check the units: 1 kPa ≈ 10.2 cm H₂O ≈ 7.5 mm Hg.

Grade leaks by timing (cough only, expiratory, inspiratory or continuous; Cerfolio) and on the numbered leak meter. Water seal stopped 67% of post-resection leaks by day 3 vs 7% on suction, but leaks of 4/7 or more often caused a pneumothorax (Cerfolio 2001). Digital units report flow in mL/min: 6 of 14 RCTs after lung resection found shorter drainage and 8 no difference, though all 4 meta-analyses favored digital units (EJCTS 2025 review); a common removal threshold is ≤20 mL/min for 6 hours.

Insertion, sizing and assisting

One French is a third of a millimeter, so 12 F is 4 mm. BTS 2023 uses Seldinger drains of 14 F or less for most pneumothoraces, effusions and infection, and large bore for unstable trauma, after thoracic surgery (28–32 F) and for big leaks, including ventilator barotrauma; above 32 F adds little, and trocars should not be used.

The safe triangle is bounded by latissimus dorsi, pectoralis major and a line at nipple level, apex below the axilla; the needle passes over the top of the rib. BTS 2023 calls for ultrasound for fluid, aspiration of air or fluid before the drain goes in, a holding suture (unsutured small drains fall out twice as often) and a film within hours. Lidocaine 1% up to 3 mg/kg; electively, warfarin stops 5 days before (INR ≤1.5) and DOACs 24–48 hours.

1. Before: consent, time-out, analgesia, position (arm behind the head, or sitting forward), unit primed (water seal 2 cm, wet suction 20 cm).
2. During: watch rhythm, SpO₂ and blood pressure for vasovagal bradycardia and bleeding; note the first drainage.
3. After: secure connections, dress the site, document the skin depth mark and output, get the film.

Drain large effusions only at the ordered rate. The BTS 2023 procedures statement stops at 1,000 mL, waits an hour, then allows 500 mL/h; the guideline's malignant-effusion section allows 1.5 L in the first hour, then 1 L/h. Stop sooner for cough, chest tightness or vagal symptoms.

Reading the drain and troubleshooting

• Disconnection: if it was bubbling or the patient is worse, reconnect at once or put the tube end 2–3 cm under sterile water; otherwise close the tap, clean the connector and fit new sterile tubing (BTS 2023).
• Unit knocked over: set it upright; replace it if the water seal no longer reaches its line.
• Tube out: occlusive dressing, lift a corner if tension develops, film, check the tube is complete.
• Tube partly out (side hole visible, depth mark moved): secure it, never push it back in, get a film.

Routine stripping creates high negative pressure without improving drainage (Halm 2007, AJCC review); milking visible clot is left to unit policy, mainly for mediastinal tubes after cardiac surgery, where falling output with rising CVP, hypotension and pulsus paradoxus means tamponade until proven otherwise.

Persistent air leak, fistula and the ventilated patient

An alveolar–pleural fistula leaks from peripheral lung; a bronchopleural fistula connects a bronchus to the pleura, usually a failed stump after resection, necrotizing pneumonia or ARDS barotrauma. After lung resection a leak beyond 5 days is prolonged; in spontaneous pneumothorax BTS 2023 seeks surgical advice when a leak persists despite 5–7 days of drainage (BTS 2010 said 3–5).

Check the system, then match the drain to the leak: a leak that outruns the drain needs a larger tube or high-volume suction, the one established use of suction (BTS 2023); otherwise suction has no proven benefit for persistent leak and increases fistula flow. For patients unfit for surgery: autologous blood patch (50–100 mL through the drain after 5 days of leak, tubing raised or tap closed for 30 minutes; infection up to 9%), chemical pleurodesis or endobronchial valves.

After pneumonectomy, a drain, if present, never goes on standard suction, which would shift the mediastinum; surgeons use a balanced system or keep it clamped. Sudden cough with serous sputum, new subcutaneous emphysema or a falling air–fluid level suggests a stump fistula: operated side down, so space fluid cannot spill into the remaining lung, and call the surgeon.

On the ventilator, barotrauma risk rises with plateau pressure above 30 cm H₂O, ARDS and auto-PEEP. A fistula bubbles on inspiration; its size is inspired minus expired tidal volume (500 in, 350 out: 150 mL per breath). Use the lowest PEEP, tidal volume, mean airway pressure and inspiratory time that maintain gas exchange, accept hypercapnia, and move to spontaneous modes early. Keep drain suction low: high suction pulls gas through the fistula and can auto-trigger the ventilator. Refractory leaks may need independent lung ventilation, bronchoscopic valves or ECMO.

Complications, re-expansion edema, daily care and transport

Re-expansion pulmonary edema is permeability edema in the re-expanded lung, usually within the first hour. It is seen on film after up to a third of pneumothorax drainages but is symptomatic after under 1% of thoracenteses; a 2020 NHS safety alert counted 16 cases in 3 years, with 2 deaths (BTS 2023). Risk rises with young age, large collections, longer collapse (often quoted as over 72 hours), large volumes and early suction. For cough, chest tightness or falling SpO₂: close the drain (effusion), oxygen, film, CPAP or high-flow if needed (only with an open drain in pneumothorax); diuretics are not evidence-based.

• Respiratory and pain: work of breathing, breath sounds, SpO₂, ventilator pressures; enough analgesia to cough, use the incentive spirometer and walk.
• Site and system: occlusive dressing, suture intact, depth mark unchanged; unit upright and below the chest, no dependent loops, water seal at its line, suction as prescribed.
• Output: volume and character each shift, hourly when bleeding; mark level and time on the chamber.
• Mobility: walk on water seal with suction disconnected, or on a digital unit; never clamp to walk.

For transport, hang the unit upright below the chest and never clamp it; disconnect suction so it runs on water seal, or bring portable or digital suction for a large leak. Dry-seal units and Heimlich valves work at any angle; water seals spill when tipped. Trapped gas expands by about a third at an 8,000 ft cabin altitude (Boyle's law), so check the drain before flight. After a pneumothorax, BTS 2023 advises no commercial flight until a film shows resolution, then a 7-day wait.

Removal and what remains unsettled

• Pneumothorax: no bubbling, even with a cough, usually for 12–24 hours, and an expanded lung on a film after time on water seal.
• Effusion: output under the agreed threshold, commonly 100–200 mL a day; after lung resection up to 450 mL/day of non-chylous fluid is accepted (Cerfolio 2008, 0.55% readmitted for effusion).
• Pleural infection: clinical improvement, thin low-volume drainage and a small residual collection.

Give analgesia first, cut the holding suture and ready an occlusive dressing. A spontaneously breathing patient does a Valsalva or holds the breath at end-inspiration or end-expiration: recurrence was 8% vs 6% (Bell 2001, 102 trauma tubes), and BTS 2023 says timing does not matter with a Valsalva. On a ventilator, pull during a delivered breath. Remove in one steady pull, occlude at once, tie the closing suture for large-bore tubes, and watch for dyspnea, falling SpO₂ and crepitus; BTS 2023 says a post-removal film should be considered.

Still unsettled: suction or water seal after lung resection, where trials conflict; conservative care for large primary pneumothorax, since the PSP result depends on how missing data are handled; clamping trials before removal, with no prospective data; and early VATS or tPA–DNase first for pleural infection, which varies by center.

Exam pearls

• Water seal 2 cm; wet suction is set by water depth (usually 20 cm), so turning up the wall only increases bubbling.
• Tidaling rises with spontaneous inspiration and falls with a ventilator breath; no tidaling means a re-expanded lung or a blocked tube.
• Bubbling with expiration or cough is an expected air leak; continuous bubbling is a large fistula or a system leak, found by brief clamping from the chest outward.
• Tension is a clinical diagnosis: decompress at the 4th or 5th space just anterior to the mid-axillary line, or by finger thoracostomy (ATLS 11); tracheal deviation is late.
• Massive hemothorax: 1,500 mL on insertion or 200 mL/h for 2–4 hours means thoracotomy (ATLS).
• Light's criteria: protein ratio >0.5, LDH ratio >0.6 or LDH >two-thirds of the upper normal serum value means exudate; pH ≤7.2 in suspected infection means drain.
• Re-expansion edema: control drainage of large effusions, avoid early suction, stop for cough or chest tightness.
• Never clamp a bubbling tube or clamp for transport; a disconnected tube goes under sterile water or is reconnected.
• After pneumonectomy, no suction on the drain; suspected stump fistula means operated side down.