Cardiac, Thoracic, and Vascular: Lung Flashcards by Anna Rachel Shajee

Lung: Anatomy

The lungs are divided into three lobes with 10 segments

on the right and two lobes with nine segments on the

left (Fig. 18-1). The decreased number of divisions on

the left can be thought of as space taken up by the

heart. The right mainstem bronchus forms a gentler

curve with the trachea than does the left mainstem

bronchus (Fig. 18-2). Therefore, aspirated foreign

bodies are more likely to lodge in the right mainstem

bronchus. In aspiration pneumonia, the aspirated

material is most likely to deposit in the most depen-

dent portions of the lungs. For a supine individual,

these are the posterior segments of the upper lobes

and the superior segments of the lower lobes. The

arterial supply to the lungs is through the pulmonary

arteries as well as the bronchial arteries, which arise

from the aorta and intercostal vessels.

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Benign Tumors of the Trachea and Bronchii: Pathology

Types of benign tumors include squamous papilloma,

angioma, fibroma, leiomyoma, and chondroma.

Squamous papillomatosis is associated with human

papilloma viruses 6 and 11.

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Benign Tumors of the Trachea and Bronchii: Epidemology

Truly benign neoplasms of the trachea and bronchi

are rare.

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Benign Tumors of the Trachea and Bronchii: History

Patients commonly present with recurrent pneumo-

nias, cough, or hemoptysis.

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Benign Tumors of the Trachea and Bronchii: Physical Examination

Patients may have decreased breath sounds on the

affected side, with the additional signs and symptoms

owing to postobstructive pneumonia.

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Benign Tumors of the Trachea and Bronchii: Diagnostic Evaluation

Chest radiography may demonstrate a mass, and

there is often a postobstructive pneumonia if the

lesion significantly narrows the bronchial lumen.

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Benign Tumors of the Trachea and Bronchii: Treatment

Angiomas frequently regress, and observation is rec-
ommended. Other lesions require surgical removal

to relieve symptoms and establish a diagnosis. This

may require partial lung resection or sleeve resection,

where a segment of bronchus is removed and pri-

marily reanastomosed. Squamous papillomatosis has

a high recurrence rate.

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Tracheobronchial Tumors with Malignant Potential

Tumors with malignant potential include bronchial

carcinoids, adenoid cystic carcinoma, and mucoepi-

dermoid tumors. Carcinoid tumors, which are malignant

in approximately 10% of patients, may cause parane-

oplastic syndromes through release of various substances,

including histamine, serotonin, vasoactive intestinal

peptide, gastrin, growth hormone, insulin, glucagon, and

catecholamines.

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Tracheobronchial Tumors with Malignant Potential: Epidemiology

These tumors make up fewer than 5% of all pulmonary

neoplasms and have no obvious age or sex predilec-

tion. Carcinoids make up approximately 1% of all lung

tumors; adenoid cystic carcinoma, approximately 0.5%;

and mucoepidermoid, approximately 0.2%.

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Tracheobronchial Tumors with Malignant Potential: History

Patients most commonly complain of cough, dyspnea,

hemoptysis, or recurrent pneumonia. Less frequently,

carcinoid tumors may produce carcinoid syndrome,

with complaints of flushing and diarrhea, as well as

manifestations of specific hormone excess. This syn-

drome only occurs in approximately 3% of patients

with carcinoid tumors.

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Tracheobronchial Tumors with Malignant Potential: Physical Examination

The patient may have respiratory compromise or

decreased breath sounds. Carcinoid tumors may cause

valvular heart disease with signs of pulmonic stenosis or

tricuspid regurgitation.

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Tracheobronchial Tumors with Malignant Potential: Diagnostic Evaluation

Chest radiography may reveal a lesion or postobstruc-

tive pneumonia. Bronchoscopy is useful to obtain tissue

diagnosis and define bronchial anatomy. Computed

omography (CT) of the chest is routine for preoper-

ative planning.

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Tracheobronchial Tumors with Malignant Potential: Treatment

These tumors should all be resected. Long-term sur-

vival for carcinoid tumors is 80%; for adenoid cystic

carcinoma and mucoepidermoid tumors, the progno-

sis is also favorable.

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Lung Cancer: Epidemiology

Lung cancer is the leading cause of cancer-related death

for both men and women in North America, responsi-

ble for greater than 150,000 deaths each year in the United States and accounting for almost 30% of all cancer-related

deaths. More than 80% of lung cancers are smoking-

related (Fig. 18-3). In the United States, more people

die each year from lung cancer than from breast, pros-

trate, and colorectal cancers combined. Lung cancer

kills more men than prostate cancer and more women

than breast cancer. Lung cancer incidence rates among

women continue to increase. Deaths from lung can-

cer in women have increased 400% between 1960

and 1990. Smoking cessation significantly reduces

an individual’s risk of developing lung cancer, although

the level of risk remains greater than for nonsmokers.

Asbestos, formaldehyde, radon gas, arsenic, uranium,

chromates, and nickel have been identified as carcino-

gens, especially when combined with smoking.

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Lung Cancer: Pathology

Lung cancer is divided into small-cell lung cancer

(SCLC; 20% to 25%) and non–small-cell lung cancer

(NSCLC; 75% to 80%). NSCLC is further divided

into squamous cell carcinoma (30%), adenocarcinoma

(35%), and large-cell carcinoma (10%). SCLC is usually

centrally located and may be associated with parane-

oplastic syndromes. Approximately 5% of patients have

symptoms of inappropriate secretion of antidiuretic

hormone, whereas 3% to 5% have Cushing’s syndrome

from adrenocorticotropin production. Squamous cell

cancer usually occurs centrally and can be associated

with symptoms of hypercalcemia secondary to produc-

tion of a substance similar to parathyroid hormone.

Adenocarcinoma typically occurs at the periphery.

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Lung Cancer: History

Most patients come to seek medical attention as a

result of signs and symptoms indicating advanced dis-

ease. Ninety percent of patients with lung cancer are

symptomatic at the time of diagnosis. Worsening

cough with increased sputum production and hemop-

tysis often indicates airway obstruction by tumor. A

history of recurrent pneumonia requiring antibiotic

therapy is common. Persistent chest, back, or shoulder

pain is related to nerve involvement or direct tumor

invasion. Bone pain indicates distant skeletal metas-

tases, whereas neurologic symptoms indicate brain

metastases. Systemic symptoms include fatigue, loss of

appetite, and unintentional weight loss.

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Lung Cancer: Physical Examination

Chest auscultation may reveal diminished breath

sounds owing to pneumonia or malignant pleural effu-

sion. Supraclavicular lymphadenopathy may be pres-
ent. Recent onset of hoarseness indicates involvement

of the recurrent laryngeal nerve. Horner syndrome

(ptosis, myosis, and anhydrosis) results from a superior

sulcus tumor causing neural invasion. Superior vena

cava syndrome and Pancoast syndrome (shoulder and

arm pain on the affected side) may occur. Paralysis of

the diaphragm indicates phrenic nerve involvement.

Patients with advanced disease are usually ill-appearing

and exhibit significant weight loss.

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Lung Cancer: Diagnostic Evaluation

Chest x-ray is often the modality first used to diag-

nose a malignant pulmonary lesion. Chest CT includ-

ing the liver and adrenal glands often follows to delin-

eate tumor size, presence of lymphadenopathy and

pleural effusion, and evidence of the likelihood of dis-

tant disease (Fig. 18-4).

Bone scan and brain imaging may also be obtained,

if necessary. Noninvasive functional testing for distant

disease can be conducted via positron emission tomog-

raphy scan. This information allows for clinical staging

and decision making.

Invasive testing is usually required for definitive

diagnosis. Diagnostic thoracentesis is used to evaluate

for malignant pleural effusion. Flexible bronchoscopy

allows for tissue biopsy and bronchial washings. Trans-

thoracic CT-guided fine-needle biopsy can also provide

diagnostic tissue sampling. Mediastinoscopy with lymph

node biopsy can be diagnostic while also providing

information for accurate nodal staging (Fig. 18-5).

Lung Cancer: Staging

The TNM system is used for staging of lung cancer (Tables 18-1 and 18-2). T1 lesions are less than 3 cm; T2 lesions are greater than 3 cm or involve the main bronchus greater than 2 cm from the carina or involve the visceral pleura. T3 lesions invade the chest wall, diaphragm, mediastinal pleura, or pericardium or involve the main bronchus within 2 cm of the carina. T4 lesions invade the heart, great vessels, mediastinum, trachea, esophagus, vertebral bodies, or carina or have malignant effusions or satellite tumors.

N1 lesions have positive nodes in the ipsilateral

peribronchial or hilar region. N2 lesions have positive

nodes in the ipsilateral mediastinal or subcarinal region.

N3 lesions have metastases either to contralateral nodes

or ipsilateral scalene or supraclavicular regions.

Stage IA lesions are T1N0M0 lesions. Stage IB

lesions are T2N0M0 lesions. Stage IIA lesions are

T1N1M0 lesions. Stage IIB lesions are T2N1M0 or

T3N0M0 lesions. Stage IIIA lesions are T3N1M0,

T1N2M0, T2N2M0, or T3N2M0 lesions. Stage IIIB

lesions are tumors without distant metastases, includ-

ing primary tumors to T4 and N3 regional lymph

node metastases. Stage IV patients have evidence of

distant metastases.

Lung Cancer: Treatment (Part 1)

Since the first successful pneumonectomy for lung

cancer in 1933, surgical resection has been consid-

ered the standard therapy for patients with poten-

tially curable disease. For patients with NSCLC, those

with clinical stage I and II disease are referred for an

attempt at curative surgical resection. For patients

with stage III disease, some may be considered for

resection as part of a multimodality therapeutic pro-

gram usually involving neoadjuvant chemoradiother-

apy. Patients with N3 disease and clinical stage IV are

not typically candidates for surgical resection

Lung Cancer: Treatment (Part 2)

Standard surgical treatment of NSCLC consists

of complete resection of the disease. In addition to

parenchymal resection, the operation should also

include either sampling or removal of all intratho-

racic ipsilateral lymph node stations into which the

tumor could potentially drain. For tumors confined

to a single lung lobe, the most common surgical pro-

cedure performed is lobectomy. For tumors invading

an adjacent lobe, a bilobectomy is required. If com-

plete resection requires removal of all lobes on the

effected side, then pneumonectomy is performed.

For a patient with poor pulmonary function and lim-

ited pulmonary reserve, then segmentectomy or

wedge resection may be performed. However, the

decision to perform a smaller resection provides

poorer overall survival because studies show higher

locoregional recurrence rates after segmentectomy

versus the more oncologically complete lobectomy

(23% versus 5%).

Lung Cancer: Treatment (Part 3)

Results of clinical trials now support the use of

adjuvant platinum-based chemotherapy in patients

with completely resected lung cancer (stage I, II, and

IIIA). The use of adjuvant chemotherapy improves

5-year survival rates by approximately 5% to 15%

when compared with surgical therapy alone. Standard

chemotherapy regimens for NSCLC include a plat-

inum agent (cisplatin or carboplatin) combined with

a nonplatinum agent (etoposide, irinotecan, pacli-

taxel, gemcitabine, and others). Radiotherapy is

often added if mediastinal lymph nodes are involved

(stage III).

Lung Cancer: Treatment (Part 4)

As opposed to NSCLC, SCLC is usually widely

disseminated at the time of diagnosis, so surgery is

rarely indicated. Only very early-stage small-cell

tumors (T1 to T2, N0) are considered for potential

resection. The standard treatment for this aggressive

disease is combined chemotherapy and radiother-

apy. Chemotherapy usually consists of combination

therapy (including cyclophosphamide, doxorubicin,

vincristine, cisplatin, carboplatin, or etoposide), with

triplet combinations often used. Radiation therapy,

usually in combination with chemotherapy, is an

important modality for treating SCLC. Various radi-

ation treatment plans exist, with differing doses,

timing, and fractionation schedules. Elective whole-

brain irradiation is used in many centers to mini-

mize the risk of developing brain metastases. The

principle of brain irradiation is to destroy any hid-

den tumor cells that may potentially lurk in the

brain, because asymptomatic cerebral metastases are

theoretically protected from systemic chemother-

apy by the blood-brain barrier. By undergoing so-

called prophylactic cranial irradiation, it is argued

that survival rates are increased and symptomatic

metastases are prevented, because approximately

25% to 50% of untreated patients will develop brain

metastases.

Lung Cancer: Prognosis

Lung cancer remains a lethal disease, despite recent
advances. The 5-year survival rate for all patients is

slightly greater than 10%. For early-stage asymptomatic NSCLC (stage IA), usually detected incidentally on chest

radiograph, the 5-year survival rate is approximately

80%. This figure rapidly decreases to 55% for stage

IB and to 30% for stage II disease. Given the overall

poor survival rates, there has been a resurgence of

interest in screening tests using spiral CT scans for

early detection of lung cancer. This is an active area

of ongoing research. Long-term survival in SCLC is

rare.

Mesothelioma: Pathology

* Mesothelioma is a malignant lesion derived most commonly from the visceral pleura.

Mesothelioma: Epidemiology

* Mesothelioma is rare. Asbestos is the major risk factor. Cigarette smoking markedly increases the incidence of mesothelioma in patients exposed to asbestos.

Mesothelioma: History

* Chest pain from local chest wall extension, dyspnea secondary to pleural effusion, and lung entrapment, weight loss, and unexplained night sweats may occur.

Mesothelioma: Physical Examination

* The patient may have decreased breath sounds on the side of the tumor as a result of pleural effusion and lung entrapment.

Mesothelioma: Diagnostic Evaluation

* Chest radiography often demonstrates a pleural effu- sion. Thoracocentesis typically yields bloody fluid, and cytology is often negative for malignant disease. CT scan shows a chronic effusion with irregular thickened visceral pleura. Patients with a suggestive history and a recurrent pleural effusion with no clear cause should undergo thoracoscopy and pleural biopsy, even in the presence of negative fluid cytology.

Mesothelioma: Treatment

* Overall prognosis is poor, with few survivors living beyond 2 years. Early-stage lesions may be resectable but require induction chemotherapy followed by extrapleural pneumonectomy, a significantly morbid procedure. Chemotherapy and radiotherapy are used for nonoperative patients.

Pneumothorax

* The lung is covered by visceral pleura, and the inner chest wall is covered by parietal pleura. These two continuous surfaces form a potential space. Simple pneumothorax occurs when air enters this space and he lung falls away from the chest wall resulting in a “dropped” lung (Fig. 18-6). Open pneumothorax occurs when a defect in the chest wall allows contin- uous entry of air from the outside (Fig. 18-7). Tension pneumothorax occurs when air enters the potential space but cannot escape. A ball valve–like effect allows pressure to increase within the hemithorax, thereby forcibly collapsing the ipsilateral lung and compressing mediastinal structures.

Pneumothorax: Etiology

* Spontaneous pneumothorax is usual seen in young thin males with rupture of congenital apical blebs or in older patients with bullous emphysema from smoking. It can also occur in patients on mechanical ventilation, espe- cially if high inspiratory pressures are required. Infection, specifically tuberculosis or Pneumocystis carinii, can cause pneumothorax, as can lung tumors on rare occasion. Placement of central venous catheters results in pneu mothorax in 1% of cases. The use of ultrasound guid- ance for central line placement in the internal jugular position reduces the chance of pneumothorax to nearly zero. Thoracocentesis, needle biopsy, and operative trauma are other iatrogenic causes. Open pneumoth- orax is caused by penetrating trauma, whereas tension pneumothorax can occur by any of the above mecha- nisms.

Pneumothorax: History

* Patients can be entirely asymptomatic, or they may complain of dyspnea or pleuritic chest pain.

Pneumothorax: Physical Examination

* Simple pneumothorax may result in decreased breath sounds and hyperresonance on the affected side. Tension pneumothorax may cause tachycardia, hypotension, and hypoxia, and the trachea may be displaced away from the affected side.

Pneumothorax: Diagnostic Evaluation

* Chest radiography reveals absence of lung markings in the affected area, usually in the apex, in an upright film. A visible line corresponding to the visceral pleu- ral surface of the lung is evident. Tracheal deviation or mediastinal shift suggests tension pneumothorax.

Pneumothorax: Treatment

* Simple pneumothoraces of less than 20% can be observed if no increase in size is demonstrated on serial chest x-rays and the patient is hemodynami- cally stable. Indications for chest tube placement include size 20% or those that demonstrate increase in size during serial radiographic observation. Open pneumothorax requires repair of the defect and tube thoracostomy. Symptomatic tension pneumothorax is a surgical emergency and requires immediate needle thoracostomy, usually in the midclavicular line in the second intercostal space on the affected side. This will decompress the chest and allow normalization of hemodynamics and oxygenation. Tube thoracostomy should then follow (Fig. 18-8).

Empyema

Empyema is an infection within the pleural space.

Empyema: Etiology

* Empyema is most commonly caused by pneumonia, lung abscess, recent thoracic surgery, or esophageal per- foration. The most common organisms are those that cause primary lung infection, including Staphylococcus, Streptococcus, Pseudomonas, Klebsiella, Escherichia coli, Proteus, and Bacteroides .

Empyema: History

* The patient may have a history of previous pneumo- nia, thoracic surgery, or esophageal instrumentation. Fatigue, lethargy, and shaking chills may occur.

Empyema: Physical Examination

* The patient is often systemically ill. Fever and decreased breath sounds at the affected lung base are common.

Empyema: Diagnostic Evaluation

* The serum white blood cell count is elevated. Chest radiography reveals a pleural effusion. Chest CT shows a defined fluid collection (Fig. 18-9). Aspiration of the pleural fluid by thoracentesis shows an exudative effu- sion, characterized by a high white blood cell count with predominantly polymorphonuclear cells, a low pH, a low glucose, and high lactate dehydrogenase. Bacteria on Gram stain and culture may be present.

Empyema: Treatment

* On rare occasions, antibiotics and needle aspiration alone are successful, but usually tube thoracostomy is required. For patients who have inadequate re-expan- sion owing to “trapped” lung after chest tube insertion, surgical decortication may be required to remove the restricting pleural peel and facilitate lung re-expansion.

Lung: Key Points

* Benign lesions of the trachea and bronchi are rare. Sleeve resection or partial lung resection may be required for treatment. * Carcinoid tumors can release a variety of substances, causing paraneoplastic syndromes. * Lung cancer is the leading cause of cancer-related death in North America. More than 80% of lung can- cers are smoking-related. Most patients are sympto- matic at the time of presentation and are not surgical candidates. Accurate preoperative staging is required to determine appropriate treatment. * Early-stage lung cancer is treated with surgery and chemotherapy. * Asbestos is the major risk factor for developing mesothelioma. Cigarette smoking greatly increases the risk of developing mesothelioma. Prognosis is poor. * Tension pneumothorax is a surgical emergency and requires rapid decompression. * Empyema is treated with tube thoracostomy and antibiotics. Surgical decortication may be required.