Perioperative Managment Of Pneumothorax

• In most reported series, the rate of recurrence of spontaneous pneumothorax on the same side is as much as 30% and on the contralateral side is approximately 10%.

• Reexpansion pulmonary edema may occur.

• Tension pneumothorax can occur after spontaneous pneumothorax but is more common after traumatic pneumothorax or with mechanical ventilation.

• Bronchopleural fistula occurs in 3-5% of patients.

• Pneumomediastinum and pneumopericardium may develop

Race: From limited data, PSP appears to be more common in the Scandinavian population, although reasons for this are unknown.

Sex: Male-to-female ratio of PSP averages 4-5:1. This ratio may vary depending on where the study is done. The male-to-female ratio of SSP averages 2-3:1.

Age: PSP typically occurs in tall thin males aged 10-30 years. PSP rarely occurs in persons older than 40 years.

SSP typically occurs later in life (60-65 years) when the peak incidence of chronic lung disease increases in the general population.

Clinical Details: Pneumothorax is classified into the following categories:

• Spontaneous pneumothorax
  • Primary

  • Secondary

• Traumatic pneumothorax
  • Resulting from direct (blunt) chest trauma

  • Resulting from penetrating chest trauma

• Iatrogenic pneumothorax
  • Resulting from biopsy procedure

  • Resulting from therapeutic procedures

• Catamenial pneumothorax

• Pneumothorax in AIDS

Primary spontaneous pneumothorax

Most episodes (90%) of PSP occur while the patient is at rest. Chest pain and dyspnea, either alone or in combination, are the classic symptoms of spontaneous pneumothorax; pain was the sole complaint of 69% of 72 patients in 1 series reported by Lindskog and Halasz. Chest pain may be minimal or severe and usually is sharp and pleuritic. Symptoms usually resolve within 24 hours, even if the pneumothorax remains untreated and does not resolve.

The primary physical sign of pneumothorax is a decrease or absence of breath sounds despite normal or increased resonance on percussion. However, this may be difficult to detect, particularly in patients with a small pneumothorax or in those who have underlying emphysema. Patients with a small pneumothorax (involving <15% of hemithorax) may have a normal physical examination. Tachycardia is the most common physical finding.

Large pneumothorax can cause decreased movement of the chest wall, a hyperresonant percussion note, diminished tactile focal fremitus and resonance, and decreased or absent breath sounds on the affected side. Hemodynamic instability, which is indicated by tachycardia, hypotension, and cyanosis, suggests tension pneumothorax. Arterial blood gas may reveal acute respiratory alkalosis and an increased alveolar-arterial oxygen gradient.

Unusual clinical manifestations of pneumothorax include ptosis (as a result of extension of subcutaneous emphysema), pneumocephalus (secondary to tension pneumothorax associated with a comminuted fracture of the thoracic spine), and recurrent pneumopericardium (in association with pleuropericardial defect).

Secondary spontaneous pneumothorax

Because of impaired pulmonary reserve, SSP results in more severe dyspnea than that occurring in PSP. Typically, chest pain is less common but more severe than in PSP. Life-threatening hypoxemia or hypotension occurs in 15% of patients. Symptoms of SSP do not resolve spontaneously. Suspicion for pneumothorax should remain heightened in patients with chronic obstructive pulmonary disease (COPD) who develop dyspnea and unilateral chest pain.

Physical findings often are subtle and may be masked by underlying lung disease, particularly in patients with COPD. Hypercapnia often occurs, with the partial pressure of arterial carbon dioxide often exceeding 50 mm Hg. Significant hypoxemia is common.

SSP is caused by the following:

• Diseases of the airways: COPD, cystic fibrosis, and status asthmaticus

• Interstitial lung diseases: Langerhans cell histiocytosis, sarcoidosis, lymphangioleiomyomatosis, tuberous sclerosis, rheumatoid disease, idiopathic pulmonary fibrosis, and radiation fibrosis

• Infectious diseases: Necrotizing Gram-negative pneumonia, anaerobic pneumonia, staphylococcal pneumonia, AIDS with P carinii pneumonia, and Mycobacterium tuberculosis

• Malignancies: Sarcoma, lung cancer

• Pneumoconiosis: Silicoproteinosis, berylliosis, and bauxite pneumoconiosis

• Connective tissue diseases

• Wegener granulomatosis

• Drugs and toxins

• Chemotherapy for malignancy

• Paraquat poisoning

• Hyperbaric oxygen therapy

• Radiation therapy

• Aerosolized pentamidine therapy in patients with AIDS

The above conditions (particularly AIDS, COPD, Langerhans cell granulomatosis, and lymphangioleiomyomatosis) can lead to unilateral or bilateral pneumothorax.

Traumatic pneumothorax

Trauma probably is the most common cause of pneumothorax. Traumatic pneumothorax can be caused by direct communication of the pleural space with the atmosphere through chest wall puncture or by disruption of the proximal tracheobronchial tree or the visceral pleura, as occurs in blunt chest trauma.

Iatrogenic pneumothorax

With the increasing use of invasive diagnostic procedures, iatrogenic pneumothorax likely will become more common, although most cases are of little clinical significance. In a review of 106 cases by Despars et al (1994), 35 cases (33%) were related to transthoracic needle aspiration biopsy, 30 cases (28%) to thoracentesis, 23 cases (22%) to subclavian vein catheterization, 7 cases (7%) to positive-pressure ventilation, and 11 cases (10%) to miscellaneous causes  In 2 of the 106 patients, the pneumothorax was fatal.

The incidence of iatrogenic pneumothorax in mechanically ventilated patients has been estimated at 0.5-15%, depending on the duration of ventilation and the nature of the underlying disease. Alveolar rupture more likely occurs when peak-inspiratory pressure is high.

Catamenial pneumothorax

Catamenial pneumothorax refers to the development of pneumothorax at the time of menstruation. Catamenial pneumothorax represents 3-6% of spontaneous pneumothorax in women. Typically, it occurs in women aged 30-40 years with a history of pelvic endometriosis (20-40%). It usually affects the right lung (90-95%) and occurs within 72 hours after the onset of menses. The recurrence rate in women receiving hormonal treatment is 50% at 1 year.

Pneumothorax in AIDS

Spontaneous pneumothorax develops in 2-6% of HIV-infected patients and is associated with P carinii pneumonia in 80% of those patients. Pneumothorax is associated with a high mortality rate in patients with HIV infection with P carinii pneumonia. The in-hospital mortality rate exceeds 25%, and the median survival rate is approximately 3 months. Pathogenesis of the pneumothorax in this setting is the rupture of large subpleural cysts, which are associated with subpleural necrosis. Recurrent ipsilateral or contralateral pneumothorax also is common.

Valsalva maneuver and pneumothorax

The Valsalva maneuver is a common etiology of pneumomediastinum and pneumothorax. This can occur during emesis, coughing, and, perhaps most commonly, during pregnancy and labor. Smoking of marijuana and cocaine, possibly associated with the use of a prolonged Valsalva maneuver to augment the "high," also has been associated with these complications in drug users. However, a more frequent mechanism for the production of pneumothorax in addicts is needle puncture while mainlining into neck veins.

Preferred Examination: Chest radiograph is the first investigation performed to assess pneumothorax because it is simple, inexpensive, rapid, and noninvasive; however, it is much less sensitive than chest CT in detecting a small pneumothorax, blebs, and bullae.

In erect patients, pleural gas collects over the apex, and the space between the lung and chest wall is most notable at that point. In the supine position, the juxtacardiac area, the lateral chest wall, and the subpulmonic region are the best areas to search for evidence of pneumothorax.

When a suggested pneumothorax is not definitively observed on an inspiratory film, an expiratory film may be helpful. At end expiration, the constant volume of the pneumothorax gas is accentuated by the reduction of the hemithorax, and the pneumothorax is recognized more easily. Similar accentuation can be obtained with lateral decubitus studies of the appropriate side (for a possible left pneumothorax, a right lateral decubitus film of the chest should be obtained, with the beam centered over the left lung).

Limitations of Techniques: CT of the chest reveals ipsilateral bullae in 89% of patients with PSP compared to 20% of control subjects matched for age and smoking status. In PSP, subpleural bullae are found in 76-100% of patients during video-assisted thoracoscopic surgery and in virtually all patients during thoracotomy.

Problems to be Considered:

Conditions that may mimic pneumothorax (eg, skin fold, clothing, tubing, chest wall artifact, localized bulla, emphysema)

Findings: The diagnosis of pneumothorax is established by demonstrating the outer margin of the visceral pleura (and lung), known as the pleural line, separated from the parietal pleura (and chest wall) by a lucent gas space devoid of pulmonary vessels The pleural line may be difficult to detect with a small pneumothorax unless high quality posteroanterior and lateral chest films are obtained and viewed under a bright light. A skin fold may mimic the pleural line, but usually, the patient is asymptomatic

In erect patients, pleural gas collects over the apex, and the space between the lung and chest wall is most notable at that point

In the supine position, the juxtacardiac area, the lateral chest wall, and the subpulmonic region are the best areas to search for evidence of pneumothorax  The presence of a deep costophrenic angle on a supine film may be the only sign of pneumothorax; this has been termed the deep sulcus sign.

When a suggested pneumothorax is not definitively observed on an inspiratory film, an expiratory film may be helpful. At end expiration, the constant volume of the pneumothorax gas is accentuated by the reduction of the hemithorax, and the pneumothorax is recognized more easily. Similar accentuation can be obtained with lateral decubitus studies of the appropriate side (for a possible left pneumothorax, a right lateral decubitus film of the chest should be obtained, with the beam centered over the left lung).

The most common radiographic manifestations of tension pneumothorax are mediastinal shift, diaphragmatic depression, and rib cage expansion). Any significant degree of displacement of the mediastinum from the midline position on maximum inspiration, or any depression of the diaphragm, should be taken as evidence of tension  although a definite diagnosis of tension pneumothorax is difficult to make on the basis of radiographic findings. The degree of lung collapse is an unreliable sign of tension, since underlying lung disease may prevent collapse even in the presence of tension.

Pleural effusions occur coincident with pneumothorax in 20-25% of patients, but usually are quite small. Hemopneumothorax occurs in 2-3% of patients with spontaneous pneumothorax. Bleeding is believed to represent rupture or tearing of vascular adhesions between the visceral and parietal pleura as the lung collapses.

False Positives/Negatives: Differentiating the pleural line of a pneumothorax from that of a skin fold, clothing, tubing, or chest wall artifact is important. Careful inspection of the film may reveal that the artifact extends beyond the thorax, or that lung markings are visible beyond the apparent pleural line. In the absence of underlying lung disease, the pleural line of a pneumothorax usually parallels the shape of the chest wall

Artifactual densities usually do not parallel the course of the chest wall over their entire length. Avascular bullae or thin-walled cysts can be mistaken for a pneumothorax. The pleural line caused by a pneumothorax usually is bowed at the center toward the lateral chest wall. Unlike in pneumothorax, the inner margins of bullae or cysts usually are concave rather than convex and do not conform exactly to the contours of the costophrenic sulcus. A pneumothorax with a pleural adhesion also may simulate bullae or lung cysts.

Findings: CT of the chest is used with increasing frequency in patients with pneumothorax. CT may be necessary to diagnose pneumothorax in critically ill patients in whom upright or decubitus films are not possible. CT may prove helpful in predicting the rate of recurrence in patients with spontaneous pneumothorax. One study by Warner et al (1991) demonstrated that patients with larger or more numerous blebs demonstrated on thoracic CT are more likely to experience recurrences.

CT demonstrates focal areas of emphysema in more than 80% of patients with spontaneous pneumothorax, even in lifelong nonsmokers. These areas are situated predominantly in the peripheral regions of the apex of the upper lobes. In patients in whom emphysema is not apparent on CT, it often is evident at surgery or on pathologic examination.

In one study by Jordan et al (1997), in 116 consecutive patients who had undergone thoracotomy for recurrent or persistent PSP or SSP, emphysema with bulla formation was identified histologically in 93 patients (80%), emphysema without bulla formation in 13 patients (11%), isolated bullae or blebs in 2 patients each, and other pulmonary or pleural abnormalities in 6 patients (5%).

In another study by Mitlehner et al (1992), localized emphysema with or without bulla formation was identified on CT in 31 of 35 patients (89%) and on radiographs in 15 of 35 patients (43%). Abnormal findings were observed in the lung ipsilateral to the pneumothorax on 28 of 35 CTs (80%) and on 11 of 35 chest radiographs (31%), and in the contralateral lung on 23 of 35 CTs (66%) and on 4 of 35 chest radiographs (11%). In most patients, the abnormal findings consisted of a few localized areas of emphysema (n<5) measuring less than 2 cm in diameter.

The mechanism of cyst or bulla rupture in SSP probably also is multifactorial. Local airway obstruction caused by pneumonia, mucous plugs, or bronchoconstriction may be important. In a retrospective study by Wait and Estrera (1992) of 120 patients with spontaneous pneumothorax admitted from 1983-1991 to Parkland Memorial Hospital in Dallas, 31 patients (26%) had localized areas of emphysema, bullae, or blebs; 12 patients (10%) had COPD; 32 patients (27%) had AIDS; and 45 patients (37%) had other underlying lung diseases. Of those with AIDS, 25 patients (78%) had P carinii pneumonia, and the remaining 7 were infected with M tuberculosis or nontuberculous mycobacteria.

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Constructed by Dr N.A. Nematallah Consultant in perioperative medicine and intensive therapy, Al Razi Orthopedic Hospital , State of Kuwait, email : razianesth@freeservers.com