Tension pneumothorax is the accumulation of air under pressure in the pleural space. This condition develops when injured tissue forms a 1-way valve, allowing air to enter the pleural space and preventing the air from escaping naturally. Arising from numerous causes, this condition rapidly progresses to respiratory insufficiency, cardiovascular collapse, and, ultimately, death if unrecognized and untreated. Favorable patient outcomes require urgent diagnosis and immediate management.
Tension pneumothorax is a clinical diagnosis that now is more readily recognized because of improvements in emergency medical services (EMS) and the widespread use of chest x-rays (see image below).
View Image | This picture shows a chest radiograph with 2 abnormalities: (1) tension pneumothorax and (2) potentially life-saving intervention delayed while waitin.... |
For excellent patient education resources, visit eMedicine's Lung and Airway Center and Breathing Difficulties Center. Also, see eMedicine's patient education articles Collapsed Lung (Pneumothorax) and Chest Pain.
Physicians defined pneumothorax during the reign of Alexander the Great. Many of the early references to pneumothorax may actually have been tension pneumothorax, which can be significantly more dramatic in its clinical presentation. Needle decompression of the chest for presumed tension pneumothorax has been in practice for nearly 20 years, but few data exist in the medical literature showing the efficacy of the procedure or reviewing the field-use and incidence of the procedure.
Tension pneumothorax remains a life-threatening condition diagnosed under difficult conditions, with a simple emergency procedure as treatment (ie, needle decompression). Although commonly used, proving the efficacy of the emergency treatment or its incidence in actual population studies is nearly impossible.
Air trapped in the pleural cavity and causing shifts of the intrathoracic structure is a life-threatening emergency. Promptly recognizing this condition saves lives, both outside the hospital and in a modern intensive care unit (ICU). Because tension pneumothorax occurs infrequently and has potentially devastating effects, a high index of suspicion and knowledge of basic emergency thoracic decompression are important for all healthcare personnel.
Although some authors are now questioning the pathophysiology of tension pneumothorax, no animal models or randomized prospective trials have provided any evidence that our understanding of the cause, effects, and treatment of the disease should be changed.
The actual incidence of tension pneumothorax outside of a hospital setting is impossible to determine. The 1999 revision of the Department of Transportation (DOT) Emergency Medical Treatment (EMT) Paramedic curriculum recommends emergent needle decompression of the chest in patients exhibiting nonspecific signs and symptoms. Approximately 10-30% of patients transported to level-1 trauma centers in the US receive prehospital decompressive needle thoracostomies; however, not all of these patients actually have a true tension pneumothorax. Although this occurrence rate may seem high, disregarding the diagnosis probably results in unnecessary deaths.
The overall incidence of tension pneumothorax in the ICU is unknown. The medical literature provides only glimpses of the frequency. From the 2000 incidents reported to the Australian Incident Monitoring Study (AIMS), 17 involved actual or suspected pneumothoraces, and 4 of those were diagnosed as tension pneumothorax. A more recent review of military deaths from thoracic trauma suggests that up to 5% of combat casualties with thoracic trauma have tension pneumothorax at the time of death.[1]
The most common etiologies of tension pneumothorax are either iatrogenic or related to trauma. They include the following:
View Image | Image depicting multiple fractures of the left upper chest wall. The first rib is often fractured posteriorly (black arrows). If multiple rib fracture.... |
View Image | Pneumomediastinum from barotrauma may result in tension pneumothorax and obstructive shock. |
View Image | A patient in the intensive care unit (ICU) developed pneumopericardium as a manifestation of barotrauma. |
Tension pneumothorax occurs anytime a disruption involves the visceral pleura, parietal pleura, or the tracheobronchial tree. The disruption occurs when a 1-way valve forms, allowing air inflow into the pleural space and prohibiting air outflow. The volume of this nonabsorbable intrapleural air increases with each inspiration because of the 1-way valve effect. As a result, pressure rises within the affected hemithorax. As the pressure increases, the ipsilateral lung collapses and causes hypoxia. Further pressure build-up causes the mediastinum to shift toward the contralateral side and impinge on both the contralateral lung and the vasculature entering the right atrium of the heart. This condition leads to worsening hypoxia and compromised venous return. The inferior vena cava is thought to be the first to kink and restrict blood flow back to the heart. It is most evident in trauma patients who may be hypovolemic with reduced venous blood return to the heart.
Researchers still are debating the exact mechanism of cardiovascular collapse, but, generally, they believe the condition develops from a combination of mechanical and hypoxic effects. The mechanical effects manifest as kinking or compression of the superior and inferior vena cava because the mediastinum deviates and the intrathoracic pressure increases. Hypoxia leads to increased pulmonary vascular resistance via vasoconstriction. In either event, decreasing cardiac output and worsening metabolic acidosis secondary to decreased oxygen delivery to the periphery occur, thus inducing anaerobic metabolism. If the underlying problem remains untreated, the hypoxemia, metabolic acidosis, and decreased cardiac output lead to cardiac arrest and death.
Clinical interpretation of the presenting signs and symptoms of a tension pneumothorax is crucial for diagnosing and treating the condition.
These findings may be affected by the volume status of the patient. In hypovolemic trauma patients with ongoing hemorrhage, the physical findings may lag behind the presentation of shock and cardiopulmonary collapse.
In nonventilated patients, the diagnosis of tension pneumothorax often requires a high level of suspicion and the presence of decreased or absent breath sounds on the affected side.
In ventilated patients, the physician may begin to suspect tension pneumothorax when increased pleural pressures necessitate an increase in peak airway pressure in order to deliver the same tidal volume. Decreased expiratory volumes secondary to air leakage into the pleural space and increased end-expiratory pressure, even after discontinuation of PEEP, are 2 other signs of tension pneumothorax in these patients. Occasionally, the development of tension pneumothorax may be delayed for hours to days after the initial insult, and the diagnosis may become evident only if the patient is receiving positive-pressure ventilation. Tension pneumothorax has been reported during surgery with both single and double lumen tubes.
Increased pulmonary artery pressures and decreased cardiac output or cardiac index are evidence of tension pneumothorax in patients with Swan-Ganz catheters.
If signs and symptoms attributable to a clinical diagnosis of tension pneumothorax as noted above (see Clinical) are present, aggressively manage with needle decompression of the chest.
Under emergency circumstances, place decompression catheters in the second rib interspace in the midclavicular line. This has been confirmed by Wax and Leibowitz who reviewed 100 thoracic computed tomography (CT) scans measuring the distance from the midline to the internal mammary artery and the average thickness of the tissues.[12] This procedure punctures through the skin and, possibly, through the pectoralis major muscle, external intercostals, internal intercostals, and parietal pleura. Placement in the middle third of the clavicle minimizes the risk of injury to the internal mammary artery during the emergency procedure. Place the catheter just above the cephalad border of the rib, because the intercostal vessels are largest on the lower edge of the rib.
If tension pneumothorax is suspected, make sure no contraindications exist for the placement of an emergency decompression catheter into the thorax.
Contraindications can include previous thoracotomy, previous pneumonectomy, and the presence of a coagulation disorder. These are relative contraindications, however, because tension pneumothorax is a life-threatening condition, and failure to treat expectantly can result in patient death.
Although laboratory and imaging studies help determine a diagnosis, tension pneumothorax primarily is a clinical diagnosis based on patient presentation. Do not delay delivery of treatment modalities while waiting for imaging or laboratory studies.
Arterial blood gas (ABG) studies show varying degrees of acidemia, hypercarbia, and hypoxemia, the occurrence of which depends on the extent of cardiopulmonary compromise at the time of collection.
Suspicion of tension pneumothorax, especially in late stages, mandates immediate treatment and does not require potentially prolonged diagnostic studies.
Ultrasonography provides a rapid imaging option for diagnosis of pneumothorax, but this evaluation should NOT delay treatment of a clinically apparent tension pneumothorax.[13, 14, 15]
X-rays showing tension pneumothorax often show 2 problems: first, the presence of tension pneumothorax, and second, the fact that an x-ray procedure was performed rather than emergent life-saving chest decompression (see the image below).
View Image | This picture shows a chest radiograph with 2 abnormalities: (1) tension pneumothorax and (2) potentially life-saving intervention delayed while waitin.... |
In the rare case that a chest x-ray is obtained safely, findings can include ipsilateral lung collapse at the hilum, trachea and mediastinum deviation to the contralateral side, and widened intercostal spaces on the affected side (see the images below). With a left hemithorax, the left hemidiaphragm may be depressed, but the liver prevents this occurrence on the right side.
View Image | An older man was admitted to the intensive care unit (ICU) postoperatively. Note the right-sided pneumothorax induced by the incorrectly positioned sm.... |
View Image | Right main stem intubation resulting in left-sided tension pneumothorax, right mediastinal shift, deep sulcus sign, and subpulmonic pneumothorax. |
No acceptable noninvasive therapy exists for this emergent life-threatening condition.
Tension pneumothorax is a life-threatening condition that demands urgent management. If this diagnosis is suspected, do not delay treatment in the interest of confirming the diagnosis.
Immediately place the patient on 100% oxygen. Perform emergency needle decompression without hesitation (see the image below). These steps are often performed before the patient reaches the hospital.
View Image | This picture shows a chest radiograph with 2 abnormalities: (1) tension pneumothorax and (2) potentially life-saving intervention delayed while waitin.... |
After needle decompression, immediately begin preparation to insert a thoracostomy tube. Then, reassess the patient, paying careful attention to the ABCs (ie, airway, breathing, circulation) of trauma management. An element of hemothorax along with the tension pneumothorax is common; therefore, the patient may require additional thoracostomy tubes.
Obtain a follow-up chest x-ray to assess for lung reexpansion, thoracostomy tube positioning, and to correct any mediastinum deviation (see the images below). Additionally, follow-up arterial blood gases may be ordered.
View Image | An older man was admitted to the intensive care unit (ICU) postoperatively. Note the right-sided pneumothorax induced by the incorrectly positioned sm.... |
View Image | Right main stem intubation resulting in left-sided tension pneumothorax, right mediastinal shift, deep sulcus sign, and subpulmonic pneumothorax. |
Monitor the patient continuously for arterial oxygen saturation.
Admit all patients with tension pneumothorax.
The basic principle or emergent needle decompression is to introduce a catheter into the pleural space, thus producing a pathway for the air to escape and relieving the built-up pressure. Although this procedure is not the definitive treatment for tension pneumothorax, emergent needle decompression does arrest its progression and serves to restore cardiopulmonary function slightly. Needle length in persons with large pectoral muscles may be an issue, and long needles or angiocatheters may be necessary.[16, 17, 18]
Administer 100% oxygen, and ventilate the patient if necessary.
Locate anatomic landmarks and quickly prepare the area to be punctured with an iodine-based solution (eg, Betadine).
Insert a large-bore (ie, 14-gauge or 16-gauge) needle with a catheter into the second intercostal space, just superior to the third rib at the midclavicular line, 1-2 cm from the sternal edge (ie, to avoid injury to the internal thoracic artery). Use a catheter or needle >4.5 cm long, and hold it perpendicular to the chest wall when inserting; however, note that some patients may have a chest wall thickness greater than 4.5 cm, and failure for the symptoms to resolve may be attributed to inadequate needle length.[16, 17, 18]
Once the needle is in the pleural space, listen for the hissing sound of air escaping, and remove the needle while leaving the catheter in place.
Secure the catheter in place, and install a flutter valve.
Prepare the patient for tube thoracostomy.
Tube thoracostomy is the definitive treatment for tension pneumothorax, and needle decompression mandates an immediate follow up with a tube thoracostomy.
Sedate the patient consciously; narcotics are optional and may not be necessary.
Locate anatomic landmarks, and administer a local anesthetic.
Prepare the area with an iodine solution (eg, Betadine) and drape.
Create a 3-cm horizontal incision in the skin, over the fifth or sixth rib along the midaxillary line.
Use a curved hemostat and dissect through the soft tissue and down to the rib.
Push the hemostat just over the superior portion of the rib, avoiding the intercostal neurovascular bundle that runs under the inferior portion of the next most superior rib. Then, puncture the intercostal muscles and parietal pleura.
Maintain the intrapleural position by inserting a finger along side of the hemostat, and remove the hemostat.
Insert the chest tube over the finger into the pleural space. A clamp may suffice for guiding the thoracostomy tube into place on the proximal end.
Look for condensation in the tube as a sign of correct placement and air evacuation.
Connect the thoracostomy tube to an underwater seal apparatus and suction.
Suture the tube in place, dress the wound, and tape the tube to the chest.
Obtain a follow-up chest x-ray to assess tube positioning and lung reexpansion.
While the patient is on positive-pressure ventilation and normal respiratory function is preserved, routinely follow up decompressed tension pneumothoraces by watching for recurrence of the condition. Chest x-ray is helpful but not required.
Misdiagnosis is the most common complication of needle decompression. If a pneumothorax but not a tension pneumothorax is present, needle decompression converts it to an open pneumothorax.
If no pneumothorax exists, the patient may develop a pneumothorax after the needle decompression is performed. Additionally, the needle may lacerate a lung, which, although rare, can cause significant pulmonary injury or hemothorax. If the needle is initially placed too medially to the sternum, needle decompression may cause a hemothorax by lacerating the inferior set of intercostal vessels or the internal mammary artery.
Thoracostomy tube placement can result in damage to the intercostal neurovascular bundle and can cause lung parenchymal injury, especially if using trocars for its placement.
Early diagnosis and immediate treatment promote a good prognosis for patients with tension pneumothorax. Overall patient prognosis greatly depends on associated injuries or morbidities.
Recent data from the Iraqi conflict suggests that tension pneumothorax accounted for death in 3-4% of combat casualties unrelated to other injuries.[1]
No controversy surrounds the emergent decompression of symptomatic tension pneumothorax. Improvement in the accuracy of diagnosis may change according to the changes in the 1999 DOT EMT Paramedic curriculum and the future availability of ultrasonographic technology for use in the field. Studies performed for the National Aeronautics and Space Administration (NASA) that are not yet published suggest that ultrasonography is useful in diagnosing pneumothorax, making it potentially useful in emergency situations (eg, tension pneumothorax).
This picture shows a chest radiograph with 2 abnormalities: (1) tension pneumothorax and (2) potentially life-saving intervention delayed while waiting for x-ray results. Tension pneumothorax is a clinical diagnosis requiring emergent needle decompression, and therapy should never be delayed for x-ray confirmation.
This picture shows a chest radiograph with 2 abnormalities: (1) tension pneumothorax and (2) potentially life-saving intervention delayed while waiting for x-ray results. Tension pneumothorax is a clinical diagnosis requiring emergent needle decompression, and therapy should never be delayed for x-ray confirmation.
An older man was admitted to the intensive care unit (ICU) postoperatively. Note the right-sided pneumothorax induced by the incorrectly positioned small-bowel feeding tube in the right-sided bronchial tree. Marked depression of the right hemidiaphragm is noted, and mediastinal shift is to the left side, suggestive of tension pneumothorax. The endotracheal tube is in a good position.
This picture shows a chest radiograph with 2 abnormalities: (1) tension pneumothorax and (2) potentially life-saving intervention delayed while waiting for x-ray results. Tension pneumothorax is a clinical diagnosis requiring emergent needle decompression, and therapy should never be delayed for x-ray confirmation.
An older man was admitted to the intensive care unit (ICU) postoperatively. Note the right-sided pneumothorax induced by the incorrectly positioned small-bowel feeding tube in the right-sided bronchial tree. Marked depression of the right hemidiaphragm is noted, and mediastinal shift is to the left side, suggestive of tension pneumothorax. The endotracheal tube is in a good position.