Pneumothorax describes the leaking and trapping of air or gas in the pleural space between the visceral and parietal pleura. The abolishment of the negative pleural pressure can result in intrapulmonary shunting, lung collapse, and hemodynamic embarrassment.
Definitions (1,2):
Non-communicating: The chest wall is intact or closed.
Communicating: The chest wall is open and air from the atmosphere directly enters the pleural space.
Tension: Results from the presence of a one-way valve where air enters and cannot leave, causing compression and displacement of mediastinal structures.
Primary spontaneous: Occurs without underlying disease.
Secondary spontaneous: Occurs as a result of underlying lung disease.
Traumatic: Accidents or iatrogenic
Perioperatively, patients with pneumothorax most often present:
Following a trauma
Iatrogenically from central line placement, brachial plexus blocks, barotrauma, or the surgical procedure
With a pre-existing diagnosis and a chest tube in situ
Epidemiology
Incidence
More than 20,000 new cases of spontaneous pneumothorax each year in the US (3).
Primary spontaneous pneumothorax (PSP) comprises ~55% of cases
Secondary spontaneous pneumothorax (SSP) comprises ~45% of cases
Of brachial plexus blocks, the supraclavicular approach has the highest incidence and ranges from 0.5–6% and diminishes with using ultrasound-guided nerve block.
Prevalence
The recurrence rate of PSP is 28% and SSP is 43%. It typically occurs within 6 months–3 years (3).
Male > female
Morbidity
New cases cost the health system around $130,000,000.00 annually
Mortality
SSP is associated with a higher morbidity and mortality than PSP.
Death is secondary to respiratory and/or cardiac arrest.
Etiology/Risk Factors
PSP occurs without underlying lung disease.
Tall, thin males, 10–30 years old
Smokers
Congenital disorders such as Marfan's syndrome and familial pneumothorax
Change in atmospheric pressure or emotional changes
Pregnancy
SSP occurs in patients with underlying lung disease (1).
Iatrogenic: During invasive diagnostic and supportive modalities like transbronchial biopsies, thoracentesis, mechanical ventilation, pleural biopsy, central venous access, brachial plexus blocks
Physiology/Pathophysiology
The thoracic space is comprised of (going from out to in):
Chest wall: Rigid, with outward expanding properties
Parietal pleura: Layer of tissue that is attached to the inner surface of the rib cage and moves in conjunction with the ribs.
Intrapleural space: A potential space that is under negative pressure and contains a small amount of fluid (provides lubrication and aids with movement). Maintains a "connection" between the chest wall and lungs (via the pleura), allowing them to move in conjunction with one another
Visceral pleura: Layer of tissue that covers the lungs, blood vessels, and bronchi
Lungs: Soft tissue without rigidity, and a tendency to collapse inward.
Leaking or trapping of air in the pleural sac can lead to a loss of negative intrapleural pressure with resultant lung collapse and outward chest wall movement. This can result in:
Intrapulmonary shunting secondary to atelectasis (perfusion without ventilation)
Decreased pulmonary compliance from decreased lung volumes. Manifests as increased peak and mean pressures
Tension pneumothorax if a one-way valve traps air within the intrapleural space with each inspiration. Pressure develops and accumulates without a means to escape and can cause compression and displacement of mediastinal structures (heart, great vessels). Severe hypotension or cardiac arrest as well as hypoxia and respiratory arrest can occur.
Prevantative Measures
Ventilator settings should be adjusted to decrease peak and mean pressures
for subclavian line placement
Consider ultrasound guidance
In mechanically ventilated patients, decrease tidal volumes; in awake, spontaneously ventilated patients, ask the patient to hold their breath after exhaling.
Utilize a shallow angle for needle insertion
Minimize the number of attempts and consider alternate sites, if appropriate
for brachial plexus blocks, consider ultrasound guidance, in particular with supraclavicular blocks
Prior to sternotomy, hold inspiration
Diagnosis⬆⬇
Intraoperatively
History: Trauma patients; recent central line placement or brachial plexus block; high peak or mean pressures needed to mechanically ventilate the patient; recent surgical events; smokers; tall thin males; and underlying pulmonary disease
Symptoms: Dependent upon the size and speed by which it occurs. In awake patients, sudden onset of chest pain associated with shortness of breath, coughing.
Chest: Rapid shallow breathing, dyspnea, deviation of the trachea, limited chest wall motion, distended neck veins; asymmetry of chest wall expansion; hyper-resonance; diminished or absent breath sounds on the side of the pneumothorax, absent egophony and bronchophony
Beck's triad: Hypotension, jugular venous distention, and muffled heart tones
Chest radiography can confirm the diagnosis as well as provide information on the size and location. It should be performed during inspiration to yield the best results. However, in the event of hemodynamic instability and high suspicion of a pneumothorax, it should not delay needle decompression (1).
Non-tension: The visceral pleura is separated from the parietal pleura and appears as a white line with no lung or vascular markings adjacent to the chest wall.
Tension: Lung tissue has collapsed and "hugs" the heart; there is a "black-out" of a large portion of the affected lung site (air); and mediastinal structures are shifted away from the affected lung.
Ultrasound scan: May be more readily available to perform. This technique is commonly used in trauma bays with the benefit of being fast and effective, and improving earlier detection. It has a sensitivity of 95–100% (superior to CXR and comparable with CT scan) (4).
Differential Diagnosis
Acute coronary syndrome
Aortic dissection
Esophageal spasm
Acute pericarditis
Pericardial tamponade
Pulmonary embolism
Pleural effusion
Pneumonia
foreign body and airway obstruction
Esophageal perforation
Treatment⬆⬇
Management strategy is based on the degree of clinical compromise, and not necessarily the size of the pneumothorax. A chest tube, or tube thoracostomy, is performed to drain the air collection and allow for re-expansion of the lung. It is attached to a drainage system with three compartments (collection, water seal, and suction control chamber). A chest radiograph is performed to verify placement (2).
Tension pneumothorax management is a clinical emergency and requires (2):
Immediate needle decompression, by placing a 14 gauge angio-catheter in the second intercostal space at the midclavicular line. If the angio-catheter is not long enough or the patient has a thick chest wall, it is possible to use the fourth or the fifth interspace as an alternative site (the chest wall is not as deep at this space)
Placement of a chest tube.
Follow-Up⬆⬇
Persistent air leak requires a thoracic surgery consult. Surgical management may be indicated for:
Persistent air leak more than 5–7 days with chest tube drainage or failure of lung re-expansion
Spontaneous hemothorax
Professions at risk (pilot, divers)
Pregnancy
Synchronous bilateral spontaneous pneumothorax
First contralateral pneumothorax
Second ipsilateral pneumothorax
Chemical pleurodesis may be indicated when the patient is not a candidate for surgery, or refuses surgical intervention (high rate of recurrence). It involves the insulation of sclerosant into the pleural space that induces aseptic inflammation with resultant adhesion of the parietal and visceral pleura. Agents include tetracycline, minocycline, talc, and doxycycline.
Air travel should be avoided until full resolution.
Diving should be permanently avoided unless instructed to do so.
Closed Claims Data
Not available
References⬆⬇
MacDuffA, ArnoldA, HarveyJ.Management of spontaneous pneumothorax: British Thoracic Society Pleural Disease Guideline 2010. Thorax. 2010;65(Suppl 2):ii18–ii31.
WarakaulleDR, TrailZC.Imaging of pleural disease. Imaging. 2004;16(4):10–21.
WakaiA, O’SullivanRG, McCabeG.Simple aspiration versus intercostals tube drainage for primary spontaneous pneumothorax in adults. Cochrane Database Syst Rev. 2007:CD004479.
LyonM, WaltonP, BhallaV, et al.Ultrasound detection of the sliding lung sign by prehospital critical care providers. Am Emerg Med. 2012; 30(3):485–488.
BaumannMH, StrangeC, HeffnerJE, et al.AACP Pneumothorax Consensus Group. Management of spontaneous pneumothorax: An American College of Chest Physicians Delphi consensus statement. Chest. 2001;119(2):590–602.
Additional Reading⬆⬇
See Also (Topic, Algorithm, Electronic Media Element)
Patients with chest tubes in situ may present for surgical procedures. The anaesthetist should identify the cause, size of the pneumothorax, and current chest tube management.
Avoid nitrous oxide in trauma patients, as a pneumothorax may be present but not identified. In addition, maintain a high degree of suspicion for the development of Beck's triad, or increases in peak and mean pressures in this patient population.