1. What is the differential diagnosis of a solitary lung mass in a middle aged smoker?

Schwartz’s Principles of Surgery – 8th Ed. (2005)

In nonselected patient populations, a new solitary pulmonary nodule observed on a chest radiograph has a 20 to 40% likelihood of being malignant, with the risk approximating 50% or higher for smokers. The remaining causes of pulmonary nodules are numerous benign conditions. Infectious granulomas arising from a variety of organisms account for 70 to 80% of this type of solitary nodule; hamartomas are the next most common single cause, accounting for about 10%. The differential diagnosis of a solitary pulmonary nodule should include a broad variety of congenital, neoplastic, inflammatory, vascular, and traumatic disorders. The initial assessment of a pulmonary nodule should proceed from a clinical history and physical examination. Risk factors for malignancy include a history of smoking, prior neoplastic disease, hemoptysis, and age over 35 years.

1. What is the CPIS (clinical pulmonary infection score) for diagnosing ventilator associated pneumonia?

ACS Surgery: Principles & Practice (2006)

The CPIS quantifies a number of clinical findings suggestive of pneumonia—temperature, WBC count, tracheal secretions, tracheal cultures, oxygenation, chest x-rays, and the presence of and progression of infiltrates on x-rays—in an attempt to diagnose pneumonia noninvasively.

LoadingA CPIS higher than 6 is associated with a high likelihood of pneumonia, and there is a clear correlation between a high CPIS and a high concentration of bacteria found with invasive culture techniques. The main use of the CPIS is as a method of defining the probability of pneumonia in a given patient that is more objective than clinical judgment alone. A patient with a low CPIS probably need not be treated for pneumonia, whereas one with a high CPIS is likely to benefit from invasive culturing, followed by rapid institution of broad-spectrum antibiotic therapy. The main drawbacks of the CPIS are (1) that all of its elements are weighted equally (for example, the presence of an infiltrate is given the same weight as a WBC count of 11,000/mm³, even though it is substantially more suggestive of pneumonia) and (2) that assessment of chest x-rays and sputum production is necessarily subjective, meaning that an equivocal CPIS could lead to an inappropriate treatment decision.

1. What are the causes of a spontaneous pneumothorax?

Schwartz’s Principles of Surgery – 8th Ed. (2005)

Spontaneous pneumothorax is secondary to intrinsic abnormalities of the lung, and the most common cause is rupture of an apical subpleural bleb. The cause of these blebs is unknown, but they occur more frequently in smokers and males, and they tend to predominate in young postadolescent males with a tall thin body habitus.
Other causes are emphysema (rupture of a bleb or bulla), cystic fibrosis, AIDS, metastatic cancer (especially sarcoma), asthma, lung abscess, and occasionally lung cancer. Management of pneumothorax in these circumstances is often tied to therapy of the specific disease process; in uncomplicated cases a simple thorascopic bleb resection and pleurodesis will suffice; more complicated cases or recurrences post pleurodesis may involve tumor resection, thoracoscopic pleurectomy, or talc pleurodesis.

1. What is the minimal amount of FEV₁ a patient would need for postoperative lung function? Why is this so?

Townsend: Sabiston Textbook of Surgery, 17th ed.

Pulmonary function testing measures the lung volumes and mechanical properties of lung elasticity, recoil, and compliance. It also evaluates gas exchange functions. Occasionally, the combined measurement of the cardiorespiratory axis serves as a more appropriate study to assess the patient’s physiologic reserve. The predicted postoperative forced expiratory volume in 1 second (FEV₁) is the most common and important predictor of postoperative pulmonary reserve. Typically, this should be greater than 0.8 L. FEV₁ may be expressed as an actual value, such as 0.9 L/sec, or as a percentage, such as 68% of that predicted. The predicted value is based on height and weight in normal patients. In addition, FEV₁ of less than 0.8 L/min suggests an increased risk of postoperative pulmonary morbidity. Patients with an FEV₁ of less than 0.5 liter have the greatest risk of postoperative pulmonary complications. [NB this is likely due to poor coughing ability postop]

1. How does non-small cell lung cancer present?

Schwartz’s Principles of Surgery – 8th Ed. (2005)

Tumors in the NSCLC group include squamous cell carcinoma, adenocarcinoma (including bronchoalveolar carcinoma), and large-cell carcinoma. Although they differ in appearance histologically, their clinical behavior and treatment is similar. As such, they are usefully thought of as a uniform group.

Squamous cell carcinoma is primarily located centrally and arises in the major bronchi, often causing the typical symptoms of centrally-located tumors, such as hemoptysis, bronchial obstruction with atelectasis, dyspnea, and pneumonia. Central necrosis is frequent and may lead to the radiographic findings of a cavity (possibly with an air-fluid level). Such cavities may become infected, with resultant abscess formation.

In contradistinction to squamous cell carcinoma, adenocarcinoma is most often a peripherally-based tumor, thus it is frequently discovered incidentally on routine chest radiographs. Symptoms of chest wall invasion or malignant pleural effusions dominate. Bronchoalveolar carcinoma and large-cell carcinoma share similar characteristics with squamous cell and adenocarcinoma.

1. What is the most common etiology and location of a lung abscess?

Schwartz’s Principles of Surgery – 8th Ed. (2005)

Lung abscess is the result of a lower respiratory tract infection only by organisms that cause necrosis. Microorganisms gain access to the respiratory tract via inhalation of aerosolized particles, aspiration of oropharyngeal secretions, or hematogenous spread from distant sites. Direct extension from a contiguous site is less frequent. Most primary lung abscesses are suppurative bacterial infections secondary to aspiration. Normal oropharyngeal secretions contain many more Streptococcus species and more anaerobes (about 10⁸ organisms/mL) than aerobes (about 10⁷ organisms/mL). Pneumonia that follows from aspiration, with or without abscess development, is typically polymicrobial. An average of two to four isolates present in large numbers have been cultured from lung abscesses sampled percutaneously. Overall, at least 50% of these infections are caused by purely anaerobic bacteria, 25% are caused by mixed aerobes and anaerobes, and 25% or fewer are caused by aerobes only.

1. What are three causes of hemopytsis?

Townsend: Sabiston Textbook of Surgery, 17th ed.

• Lung cancer
• Lung abscess
• Cavitary aspergillosis
• Tuberculosis
• Bronchiectasis
• Swan-Ganz catheterization
• Cystic fibrosis
• Broncholithiasis
• Foreign body
• Transbronchial lung biopsy
• Tuberculosis

1. Discuss the management of empyema. What is the timing of surgery?

Townsend: Sabiston Textbook of Surgery, 17th ed.

Treatment of empyema is dependent on its phase but involves the identification and systemic treatment (antibiotics) of the causative organism and complete drainage of the pleural space. In the acute and early fibrinopurulent phases, complete thoracentesis can be both diagnostic and therapeutic if the effusion is drained entirely. The prior administration of antibiotics may lead to a sterile tap, but Gram stain, cell count , chemistries (protein, LDH, amylase, and glucose), and pH (<7.3) all can be useful in making the diagnosis.

Tube thoracostomy may be indicated for pleural drainage if thoracentesis fails or the empyema has progressed beyond its earliest stages. Chest tube insertion, however, can be ineffective if the empyema has become loculated or organized. VATS empyema drainage with early pleural débridement has the added advantage of more complete pleural drainage by visualizing and breaking down loculations. Occasionally, radiologically guided catheter drainage can be a useful adjunct to these surgical procedures. Thoracotomy with débridement or formal decortication in later-stage empyema is reserved for treatment failures with persistent sepsis.

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