Needle Decompression: Sites, Needle Length and Step-by-Step Technique

Quick Answer

Needle decompression, also called needle thoracostomy, releases trapped air from the pleural space in a suspected tension pneumothorax. It is indicated when the patient is hemodynamically unstable and tension pneumothorax is the likely cause, and it buys time until a chest tube can be placed. ATLS recommends the 4th or 5th intercostal space in the anterior midaxillary line in adults, with a 5 cm needle for smaller adults and 8 cm for larger adults, while other guidance still uses the 2nd intercostal space at the midclavicular line. A catheter too short to reach the pleural space is a frequent cause of failure.

When Is Needle Decompression Indicated?

Needle decompression is indicated for a suspected tension pneumothorax that is compromising breathing or circulation. Air enters the pleural space and can’t get out, pressure builds, and the mediastinum shifts until venous return and cardiac output fall.

The diagnosis is clinical. The StatPearls review of tension pneumothorax describes severe respiratory distress, hypotension, and an enlarged, hyperresonant hemithorax with absent breath sounds, and sometimes tracheal deviation away from the affected side. Tachycardia, jugular venous distension and cyanosis can join that picture. If the patient is unstable and suspicion is high, the review calls for decompression without delay, followed by a chest tube.

Ventilation status changes what you’ll see. A systematic review of tension pneumothorax presentation found hypoxia in 50.0% of cases breathing unassisted versus 91.8% of cases receiving assisted ventilation, and the adjusted odds of hypotension were 12.6 times higher with assisted ventilation. Most ventilated patients who became hypotensive or arrested did so within minutes of presentation, so the patient you are bagging deserves the closest watch.

Who Can Perform Needle Decompression in the Field

The 2019 National EMS Scope of Practice Model lists needle chest decompression at the Paramedic level. It is a national model, and each state sets its own scope.

Whether you perform the procedure, which site you use and which device you carry all depend on your state protocols and your medical director. Treat everything below as background for your own protocol, never a replacement for it.

Pitfalls to Recognize Before You Decompress

Two recent retrospective studies, each from a single Level I trauma center, suggest the procedure is often done on soft indications and often doesn’t change the patient’s course.

• A 2024 Level I trauma center review of 63 prehospital needle thoracostomies found that, among the 54 patients who survived to arrival, only four met all of the PHTLS criteria of hypotension, difficulty ventilating and absent breath sounds. Prehospital vital signs did not change significantly after decompression.
• In the same review, 15 of the 54 patients who had imaging showed lung lacerations, and 11 catheters visible on CT were outside the chest.
• A 2026 retrospective study of prehospital needle thoracostomy in 214 adults found that only 30% improved clinically after decompression. The most common documented indication was absent or reduced breath sounds (55%), complications occurred in 14%, and one patient had a needle placed into the heart.

The 2024 authors call for closer adherence to decompression guidelines, and the 2026 authors suggest building protocols around objective measures such as confirmed hypoxia. The gap both studies describe is decompression triggered by a subjective finding, usually reduced breath sounds, without the rest of the clinical picture.

Needle Decompression Sites: 2nd ICS vs 4th/5th ICS

Two sites are in use. The anterior site is the 2nd intercostal space at the midclavicular line. The lateral site is the 4th or 5th intercostal space, at the anterior axillary line or just in front of the midaxillary line.

The case for the lateral site is chest wall thickness. A 2016 meta-analysis of chest wall thickness found a mean of 42.79 mm at the 2nd intercostal space midclavicular line versus 34.33 mm at the 4th/5th intercostal space anterior axillary line. The thickness difference did not reach statistical significance (P=.08), but the difference in predicted failure with a 5 cm needle did: 38% at the anterior site versus 13% at the anterior axillary line (P=.01).

A cadaver study comparing insertion sites points the same way. With a 14-gauge, 5 cm needle, 100% (40 of 40) of needles at the 5th intercostal space midaxillary line entered the chest, compared with 57.5% (23 of 40) at the 2nd intercostal space. The chest wall averaged 3.5 cm at the 5th space and 4.5 cm at the 2nd.

Guidelines have not converged. According to a 2025 meta-analysis in the World Journal of Emergency Surgery, ATLS recommends the 4th or 5th intercostal space in the anterior midaxillary line, while the European Trauma Course uses the 2nd intercostal space at the midclavicular line. The same authors propose that a left-sided tension pneumothorax should not be decompressed at the 5th intercostal space midaxillary line because of the risk of cardiac injury, and they say their recommendations should be interpreted with caution.

	2nd ICS, midclavicular line	4th/5th ICS, lateral
Mean chest wall thickness (Laan 2016)	42.79 mm	34.33 mm at the anterior axillary line; 39.85 mm at the midaxillary line
Predicted failure with a 5 cm needle (Laan 2016)	38%	13% at the anterior axillary line; 31% at the midaxillary line
Cadaver entry with a 5 cm, 14 g needle (Inaba 2011)	57.5%	100% (5th ICS, midaxillary line)
Recommended by	European Trauma Course; TCCC lists either site	ATLS; TCCC lists either site

Whichever site you use, the needle goes over the upper edge of the rib. The Merck Manual procedure guide places it there to avoid the neurovascular bundle.

Decompression Needle Size and Length

Catheter length decides whether the needle reaches the pleural space. A pooled analysis of chest wall thickness covering 2,558 measurements found a mean of 4.19 cm (SD 1.37 cm) and estimated that a catheter of at least 6.44 cm is needed to reach the pleural space in 95% of patients.

Clinical data match the anatomy. In a Canadian Journal of Surgery study of prehospital decompressions, 65% (17 of 26) of attempts with a 3.2 cm catheter failed to decompress the pleural space, compared with 4% (3 of 75) with a 4.5 cm catheter. All patients had blunt trauma, and the longer catheter was carried by helicopter crews and the shorter one by ground crews.

Source	Gauge	Length
Merck Manual (2025)	14 or 16 g over-the-needle catheter; some sources use 10 g	8 cm more successful than 5 cm
ATLS (as summarized by Ahmad 2025)	Not stated in summary	5 cm for smaller adults, 8 cm for larger adults
TCCC Guidelines Change 17-02 (2018)	14 g or 10 g	3.25 in
Clemency 2015 (pooled anatomy)	Not studied	At least 6.44 cm to cover the 95th percentile of chest wall thickness

Longer is not free. Merck notes that 8 cm needles succeed more often than 5 cm needles but raise the risk of injuring underlying structures, which is one more reason site and angle matter.

Pediatric Needle Decompression

Pediatric evidence is thin, and most of it is anatomical. A CT study of pediatric chest wall anatomy in 139 children aged 0, 5 and 10 years found the heart or thymus directly against the chest wall at the 2nd intercostal space midclavicular line in some young children. The authors recommend the 4th intercostal space anterior axillary line as the primary site, while noting that the intercostal space there is narrower and the intercostal vessels and nerve are at greater risk.

The same research group’s CT-based pediatric needle size study recommended catheter sizes by age for the 4th intercostal space at the anterior axillary line.

Age	Recommended catheter (Leonhard 2019)
Infant (0 years)	22 g, 2.5 cm
5 years	20 g, 3.2 cm
10 years	18 g, 4.5 cm

Both are CT-based studies from overlapping author groups, so treat them as a reference point. Your pediatric protocol decides the site and device.

How to Perform Needle Decompression, Step by Step

The steps below combine the Merck Manual procedure and TCCC Guidelines Change 17-02, which is military prehospital guidance. Where your protocol differs, your protocol wins.

1. Confirm the indication: suspected tension pneumothorax with respiratory or hemodynamic compromise, as your protocol defines it.
2. Place the patient supine and expose the chest.
3. Identify your site on the affected side, either the 4th or 5th intercostal space laterally or the 2nd intercostal space at the midclavicular line.
4. Clean the skin with chlorhexidine or povidone-iodine if time allows.
5. Enter over the upper edge of the rib below your chosen intercostal space.
6. Advance the needle and catheter perpendicular to the chest wall, all the way to the hub.
7. Hold the unit in place for 5 to 10 seconds before removing the needle.
8. Remove the needle and leave the catheter in place.
9. Reassess for an escaping hiss of air, less respiratory distress, a rising oxygen saturation or improving signs of shock.
10. Prepare for tube thoracostomy, or hand off with that as the next step.

The two sources differ slightly on angle: TCCC specifies perpendicular to the chest wall, while Merck directs the needle toward the head over the rib. The success markers in step 9 come from TCCC 17-02. The same guideline recommends no more than two decompression attempts before moving on to circulation, because hemorrhagic shock can look like tension physiology, and it calls for bilateral decompression in a combat casualty with torso trauma who goes into traumatic arrest. Civilian protocols vary on both points.

Complications and What to Do When It Doesn’t Work

The Merck Manual lists pulmonary or diaphragmatic laceration, intercostal neuralgia from injury to the neurovascular bundle, bleeding and infection as complications. It adds iatrogenic pneumothorax if the diagnosis was wrong, and rarely, perforation of other chest or abdominal structures.

A decompression can fail even when the indication was right. The catheter may be too short, as shown above. It may kink after the needle comes out, which Merck notes with 14- and 16-gauge catheters. Or the catheter may stay open and still fail to relieve tension physiology.

A swine model of tension pneumothorax showed how often these failures can occur. Of 19 needle thoracostomies that were patent on placement, 5 (26%) failed mechanically within 5 minutes from kinking, obstruction or dislodgement, and 6 of the remaining 14 did not relieve tension physiology, for an overall failure rate of 58%. Tube thoracostomy relieved it in 100% of events. It is an animal model, but it explains why a patient who improved and then slides again needs reassessment right away.

That is also the answer to needle decompression vs chest tube. The needle is a temporizing step, and the tube thoracostomy that follows is the definitive treatment.

Keeping a Rare Skill Ready

Needle decompression is a high-acuity, low-occurrence procedure. In the same Canadian Journal of Surgery study, prehospital needle decompression had been attempted in 1.5% (142 of 9,689) of patients arriving at one level-1 trauma center over four years, so most providers will go long stretches without doing one.

Landmark-finding is a known weak point. In a pilot study of EMS site selection, 30 rural paramedics and nurses picked the correct location with the landmark technique 66.7% of the time on simulated patients, and 15% of their landmark choices sat over dangerous structures. When they used ultrasound after a training session, correct selection rose to 85%.

Infrequent procedures fade without rehearsal, a problem we covered in our episode on procedural skill decay. Short, repeated practice can help you keep finding the 4th or 5th intercostal space by feel and running the steps in order on the decompression device your service carries. Some programs also add pressure to practice, the idea behind stress inoculation in procedural training.

Be clear about what practice does. Simulation builds familiarity and confidence. It doesn’t replace supervised experience or your agency’s credentialing, and the evidence linking it to patient outcomes is still limited, as the founder discussed in what the literature says about simulation.

FAQ

What are the two sites for needle decompression?

The 2nd intercostal space at the midclavicular line and the 4th or 5th intercostal space laterally, near the anterior axillary or midaxillary line. ATLS favors the lateral site in adults, the European Trauma Course uses the anterior site, and TCCC accepts either.

Can EMTs do needle decompression?

The 2019 National EMS Scope of Practice Model places needle chest decompression at the Paramedic level. Your state and medical director set the actual scope.

Do you go above or below the rib?

Above. Insert over the upper edge of the rib below your target intercostal space to avoid the neurovascular bundle.

What size needle is used for needle decompression?

Merck lists a 14- or 16-gauge over-the-needle catheter, and TCCC specifies 14 or 10 gauge at 3.25 inches. ATLS allows 5 cm in smaller adults and 8 cm in larger adults, and children need smaller catheters matched to age.

What is the success rate of needle decompression?

Technical success depends on site and needle length, and a 2016 meta-analysis put the 5 cm needle failure rate at 13% to 38% by site. In a 2026 prehospital study, only 30% of patients improved clinically, many of them decompressed on subjective findings alone.

Needle decompression vs chest tube: what’s the difference?

Needle decompression is a fast, temporizing release of pressure. A tube thoracostomy is the definitive treatment and should follow.

Conclusion

Needle decompression comes down to choosing the right patient and getting a long enough needle into the pleural space at the site your protocol names. The evidence leans toward the lateral 4th or 5th intercostal space in adults, but guidelines still disagree, and recent prehospital data suggest a bigger problem may be decompressing patients who didn’t meet the clinical criteria for tension physiology. Whatever happens with the needle, plan the chest tube from the start.

If needle decompression is in your protocol, the EMS Procedural Training course pairs a step-by-step module with simulation models you keep, alongside IO access, cricothyrotomy and chest tube insertion.

References

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