Evaluating and Managing Pneumothorax

Emerg Med 37(10):18-25, 2005

To successfully treat the patient with a pneumothorax not caused by trauma, it is essential to identify the underlying problem. The authors update diagnostic techniques and discuss key considerations in the management of different types of spontaneous as well as traumatic pneumothoraces.

By Benjamin P. Harrison, MD, FACEP, LTC, MC, USA, and Jacob A. Roberts, DO, CPT, MC, USA

By definition, a pneumothorax is any collection of air within the intrapleural space. If the amount of air is substantial, normal ventilation becomes impaired; an extreme example of this would be a tension pneumothorax. There are two main categories of pneumothorax: those that occur spontaneously and those that occur secondary to some traumatic insult. It is important to determine the cause of a pneumothorax, since proper management of these patients may vary, depending on the etiology and underlying lung disease.

DIAGNOSIS BY CHEST X-RAY

The diagnosis of pneumothorax is radiologic in all cases except when a tension pneumothorax is suspected. The first and often only test required is a standard anteroposterior (AP) chest film. The diagnosis is made by identifying a visceral pleural line separated by a space without pulmonary vasculature or lung markings adjacent to the chest wall. The overall sensitivity of chest x-rays in detecting pneumothorax is around 80%.

Care should be taken to differentiate pneumothorax from a pseudo-pneumothorax. The scapular border, skin folds, large bullae, and indwelling lines have all been misidentified as a pneumothorax.

Traditionally, expiratory chest x-rays have been thought to have a higher sensitivity than inspiratory films, but the current literature does not support that. Theoretically, the volume of the pneumothorax will not change with the various stages of respiration, which should make it more obvious on expiratory films. Recent studies have refuted this medical axiom, however, and inspiratory films should suffice to rule out a pneumothorax.

Supine chest AP films are notoriously inaccurate. Because they result in air spreading out over the anterior chest, supine films often appear normal, even in the presence of significant air. Frequently, the only indication is the "deep sulcus sign," so named because of the appearance of an especially deep costovertebral sulcus.

COMPUTED TOMOGRAPHY AND ULTRASOUND

Computed tomography (CT) is exquisitely sensitive for picking up a small, occult pneumothorax and is the best choice for diagnosing the condition in the supine trauma patient. The more prevalent use of CT scans in trauma patients has led to increased detection of pneumothorax, but the clinical utility of this is unclear. Many of these small pneumothoraces will resolve spontaneously without intervention, although their presence may have management implications in patients requiring mechanical ventilation or air transport or planning air travel. Pneumothorax is frequently and inadvertently diagnosed in the supine trauma patient undergoing CT for other concerns.

Another promising modality is ultrasound. Preliminary evidence with experienced ultrasonographers both in Europe and the United States show sensitivities for diagnosing pneumothorax approaching 100% in skilled hands. Ultrasound may also be helpful to physicians practicing in an austere environment where radiologic studies are not readily available. With proper training and experience, ultrasound should become a more useful tool for the emergency physician to utilize for the supine trauma patient or the trauma patient too unstable for CT.

Management decisions in patients with pneumothorax are based on the size of the pneumothorax, the presence of underlying lung pathology, and the clinical status of the patient. The gold standard for determining the size of a pneumothorax is CT volume measurements. Other sources quote mathematical formulas that calculate the volume of both the hemithorax and pneumothorax by measuring the diameters of both, cubing those measurements, and calculating the percentage. Both are cumbersome and generally unnecessary, however.

The most practical method is to simply grade the pneumothorax as small or large. In a small pneumothorax, the rim between the lung margin and chest wall is less than two centimeters and there are less than three centimeters from the lung apex to the cupola. In a large pneumothorax, the rim between the lung margin and chest wall is more than two centimeters and there are more than three centimeters from the lung apex to the cupola (see x-ray).

Large pneumothorax. The patient presented with shortness of breath and a chest x-ray revealed a left superior pneumothorax and loculated pneumothorax of the left costophrenic angle. White arrows outline the pleural line superiorly and inferiorly. This would be classified as a large pneumothorax since the apex-cupola distance is greater than 3 cm. Computed tomography showed partial collapse of the left lower lobe and lingula.

PRIMARY SPONTANEOUS PNEUMOTHORAX

Spontaneous pneumothorax is defined as any pneumothorax that occurs without a known traumatic insult. There are two classifications: primary and secondary spontaneous pneumothorax (see table). Overall incidence in the United States is around 20,000 cases annually.

Types of Spontaneous Pneumothorax   Type Definition Management primary spontaneous pneumothorax no previously identified lung disease • observation, aspiration, or tube thoracostomy • refer for possible preventive procedures secondary spontaneous pneumothorax known underlying lung disease • tube thoracostomy and admission • consider preventive procedures catamenial pneumothorax occurs in women during menses from thoracic endometriosis • observation, aspiration, or tube thoracostomy • refer for preventive procedures and hormonal therapy

Primary spontaneous pneumothorax (PSP) occurs in a patient without clinically apparent underlying pathology. This condition generally affects adults who smoke and are young, tall, and thin. More than 90% of patients who present with this condition are smokers. The underlying pathology in most patients is small subpleural blebs that subsequently rupture. Patients typically present with sudden onset of pleuritic chest pain and dyspnea; occasionally, they will be hypoxic and, rarely, hypercapneic.

The diagnosis of PSP is made by identifying a pleural line on a standard chest x-ray. Management depends on the clinical stability of the patient and the size of the pneumothorax. In a typical patient, a simple spontaneous pneumothorax will reabsorb at about 1.25% per 24 hours. If the patient is placed on 100% oxygen, which should be done with those under observation, reabsorption will occur four to six times faster (5% to 7% per day).

Signs of clinical instability include a heart rate of more than 120 bpm, oxygen saturation below 90%, and a respiratory rate above 24 or significant respiratory distress. Clinically stable patients with a small pneumothorax can be considered for simple observation and discharge home. The patient should be observed for four to six hours, then have a repeat chest x-ray to ensure that the pneumothorax has not increased in size. Discharge instructions should state explicitly that the patient should return immediately if symptoms redevelop. Follow-up at 12 to 24 hours should also be arranged.

USE OF ASPIRATION

Aspiration can be used for all patients with PSP and has been successful even with very large pneumothoraces. Catheter aspiration can be easily accomplished using a 14- to 16-gauge venous catheter, a three-way stopcock, and a 60-ml syringe. Aspiration can also be performed using commercially available mini-catheters. These small-bore "pigtail" catheters (under 14 Fr in size) are less traumatic for the patient and less painful than standard chest tubes. Suction may be applied if the lung does not re-expand.

When attempting simple aspiration, local anesthesia should be applied and the catheter placed through the second or third intercostal space at the mid-clavicular line or the fourth or fifth space in the anterior axillary line. Aspiration should be performed until no further air can be aspirated or the patient starts to cough from lung expansion. The catheter should then be closed off and the patient observed for four to six hours. Another chest x-ray can then be taken; if it is normal, the patient can be discharged home, assuming he or she is reliable and close follow-up can be arranged.

Another option is to attach a Heimlich valve to the catheter (without suction) and discharge the patient after a stable six-hour chest x-ray, with follow-up in 48 hours. If a film obtained at follow-up is normal, the catheter can be removed. If more than three to four liters of air are withdrawn during the initial aspiration, it should be assumed the patient has a persistent bronchopulmonary leak. A standard chest tube should be placed at that point and the patient admitted.

Tube thoracostomy should be reserved for unstable patients, those with persistent pneumothorax after attempted aspiration, and those with recurrent pneumothorax. Patients with one episode of PSP have about a 30% risk of recurrence, but admitting physicians usually will not attempt definitive treatment on the first recurrence. Depending on the institution and the underlying etiology, definitive treatment for patients with recurrent pneumothorax includes video-assisted thoracoscopy, pleurodesis with a sclerosing agent (talc powder or doxycycline), or open thoracotomy with stapling of blebs or surgical excision.

SECONDARY SPONTANEOUS PNEUMOTHORAX

Secondary spontaneous pneumothorax (SSP) is defined as a spontaneous pneumothorax in a patient with known underlying lung disease. This condition has a high association with chronic obstructive pulmonary disease, cystic fibrosis, and AIDS patients with underlying Pneumocystis carinii pneumonia (PCP). It also has a high association with tuberculosis infections, especially in developing nations. The diagnosis should be suspected in any patient with underlying pulmonary disease who presents with new-onset chest pain or dyspnea. Patients with SSP often present with significant respiratory distress, unlike those with PSP, who often have mild symptoms.

Virtually all patients with SSP will require tube thoracostomy with some form of preventive procedure performed prior to discharge. Common interventions are pleurodesis with mechanical abrasion or sclerosing agents, thoracoscopy with stapling or, in some cases, thoracotomy with surgical excision. Clinically stable patients with a small pneumothorax (less than a 1-cm apical pneumothorax) may be admitted and observed.

Patients with AIDS are a special subset. Most AIDS patients with SSP have underlying PCP and a very high incidence of recurrence. In addition, their air leaks are often persistent and not easily resolved with tube thoracostomy alone. The underlying etiology is necrotic, infected pleural tissue. Often, these patients respond poorly to preventive measures such as pleurodesis and stapling. Overall mortality is around 50%, but if the patient has a persistent bronchopulmonary leak, it is closer to 100%. A recent trend is to discharge patients with indwelling chest tubes attached to Heimlich valves after initial admission and consideration for other preventive measures.

Catamenial pneumothorax is a form of SSP found in women with thoracic endometriosis and is associated with menses. It should be suspected in women with SSP that occurs around the time of menses, especially if the condition is recurrent. There is also an association with chlomiphene citrate fertility treatment. This type of pneumothorax most commonly occurs on the right side, and these patients typically present with dyspnea and pleuritic chest pain. If catamenial pneumothorax is suspected, the patient should be treated as appropriate for the size of the pneumothorax and his or her clinical stability and admitted for further care. Often, patients will require tube thoracostomy and pleurodesis in conjunction with hormonal suppressive therapy.

TRAUMATIC PNEUMOTHORAX

Traumatic pneumothorax can occur after either penetrating or blunt trauma. Patients often will present with dyspnea, chest pain, and subcutaneous emphysema. The majority of traumatic pneumothoraces will require tube thoracostomy and admission, the only exceptions being some simple, iatrogenic pneumothoraces in stable patients and small, asymptomatic pneumothoraces found only on CT.

These pneumothoraces can be divided into three classes: simple, communicating, and tension (see table).

Traumatic Pneumothorax   Type Definition Management simple pneumothorax no communication with outside air and no mediastinal shift • observation if small and asymptomatic • aspiration, observation, and repeat chest x-ray • tube thoracostomy, admission communicating pneumothorax ("sucking chest wound") open hole in chest with free communication to outside air • cover hole, then tube thoracostomy and admission tension pneumothorax flap-valve effect creates increasing intrathoracic pressure with hemodynamic compromise needle decompression, tube thoracostomy, and admission catamenial pneumothorax occurs in women during menses from thoracic endometriosis • observation, aspiration, or tube thoracostomy • refer for preventive procedures and hormonal therapy

Simple pneumothorax. In this form of traumatic pneumothorax, there is no communication with the outside air and no mediastinal shift. The most common cause is a broken rib lacerating the pleura. Simple traumatic pneumothorax can also result from a blunt force compressing the thorax against a closed glottis or from a previous communicating pneumothorax that has been covered.

Treatment in most cases requires tube thoracostomy and admission. Some small, asymptomatic pneumothoraces identified only on CT can be managed conservatively. If, however, the patient will be placed on positive pressure ventilation, then a chest tube should be inserted. If an associated hemothorax is suspected, larger-bore thoracostomy tubes should be placed. Persistent air leaks may require additional chest tubes and bronchoscopy to evaluate for significant bronchopulmonary injury.

Communicating pneumothorax. This type of pneumothorax occurs when an open hole exists with free communication to the outside air. Also known as a "sucking chest wound," this condition most often results from a high-velocity or close-range gunshot wound. Severe ventilatory insufficiency ensues from the paradoxical collapse of the involved lung with inspiration. Treatment requires covering the open hole with an occlusive dressing and converting it to a simple pneumothorax. A chest tube is then placed. If a tube thoracostomy is not performed, the wound is at risk of becoming a tension pneumothorax.

Tension pneumothorax. A tension pneumothorax occurs when an injury creates a flap-valve effect, permitting ingress but not egress of air from the thoracic cavity. Each time the patient takes a breath, more air enters into the thoracic cavity. The result is increasing intrathoracic pressure with subsequent shifting of the mediastinal structures to the opposite side. If the pressure is not relieved, cardiac output is decreased and death may occur. Patients with tension pneumothorax may present with tachycardia, hypotension, jugular vein distension, tracheal deviation, and absent breath sounds on the involved side. The diagnosis should be based on clinical, not radiographic, findings.

If this diagnosis is suspected, the tension pneumothorax should be immediately decompressed by placing a 14- to 16-gauge angiocatheter into the second intercostal space on the midclavicular line, followed by tube thoracostomy. Some authors note that needle thoracostomy is an imperfect therapy that may lacerate the underlying lung, kink, or fail to reach the pleural space. Immediate tube thoracostomy is a reasonable alternative since needle thoracostomy is an unproven standard.

The physician should choose the method by which he or she can most quickly and effectively enter the pleural space to relieve a life-threatening tension pneumothorax. If needle thoracostomy is initially chosen, the angiocatheter used should be more than five centimeters in length to decrease failure rates, especially in the prehospital setting. As in all cases in which tube thoracostomy is performed, parenteral antibiotics should be given (preferably a first-generation cephalosporin, with redosing within the first 24 hours) to decrease the risk of infection. A post-procedure chest x-ray should be taken after catheter or chest tube insertion to verify placement and to assess the effectiveness of therapy.

Iatrogenic pneumothorax. This is a special subset of traumatic pneumothorax that occurs not infrequently after invasive thoracic procedures. Management differs, however, from that for most traumatic pneumothoraces. If the pneumothorax is small and the patient stable, management is similar to that for PSP. Many patients can be managed with observation or simple aspiration. If the patient is receiving positive pressure ventilation or is unstable, a chest tube should be placed.

Pneumothorax Pearls • Avoid the "one size fits all" approach for tube thoracostomy placement. Most pneumothoraces can be treated with smaller (16-20 Fr) tubes. Larger tubes may be used if a hemothorax or bronchopulmonary fistula is suspected. • Consider simple aspiration for patients with a first episode of primary spontaneous pneumothorax and place smaller "pigtail" catheters as a first choice for secondary spontaneous pneumothorax. Catheter aspiration is better tolerated and less painful than chest tubes and has been shown to be effective even for larger (up to 100%) pneumothoraces. • Tube thoracostomy is an extremely painful procedure and clinicians often fail to provide proper anesthesia. In stable patients, adequate analgesia/sedation should be administered, followed by generous amounts of local anesthetics when chest tubes are placed. • An initial parenteral dose of a first-generation cephalosporin should be administered for chest tube insertion in the emergency department to decrease the risk of empyema and pneumonia. • Small pneumothoraces should be treated with thoracostomy tubes if the patient is undergoing mechanical ventilation or undergoing air transport prior to transfer to another facility. • Patients being discharged home should be placed on bed rest and told to return to the emergency department immediately in the event of dyspnea, worsening chest pain, or other new symptoms that warrant concern.

TRADITIONAL APPROACHES CHALLENGED

Traditional approaches to the diagnosis and management of pneumothorax are being challenged, and physicians should keep an open mind regarding new approaches to this condition. As CT scans become cheaper and more widely utilized, their role in diagnosing pneumothorax is also evolving and being more clearly defined. More cases of small pneumothorax are being diagnosed, but management decisions are not necessarily being altered because of that (see box). Less costly and less painful alternatives (other than standard tube thoracostomy and admission) exist for many etiologies, and more patients are being discharged home than in the past. Understanding these trends is critical to providing optimal care for patients with pneumothorax.

Suggested Reading Baumann MH, et al.: Management of spontaneous pneumothorax: an American College of Chest Physicians Delphi consensus statement. Chest 119:590, 2001. Henry M, et al.: BTS guidelines for the management of spontaneous pneumothorax. Thorax 58(2):39, 2003. Heffner J and Huggins J: Editorials: management of secondary spontaneous pneumothorax. Chest 125:4, 2004. Chang A and Barton E: Pneumothorax, iatrogenic, spontaneous and pneumomediastinum. eMedicine [serial online] 2002. Available at: http://www.emedicine.com/emerg/topic469.htm. Accessed September 9, 2005. Kosowsky J: Pleural disease. In Marx J, et al. (eds): RosenÕs Emergency Medicine, 5th ed, Mosby, 2002, p. 674. Kirsch T and Mulligan J: Tube thoracostomy. In Roberts JR and Hedges JR (eds): Clinical Procedures in Emergency Medicine, 4th ed., Elsevier, 2004, p. 187. Ullman E, et al.: Pulmonary trauma: emergency department evaluation and management. Emerg Med Clin North Am 21(2):291, 2003.