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1. The answer is B (Chapter 1, I A 1). The normal adult human body is made up of 50%–70% water. The water is contained in three primary compartments of the body: intracellular, extracellular, and intravascular. On average, two thirds of the body is made of water; in the hypothetical 70 -kg man, this is 46 L. Of this 46 L, two thirds is intracellular (30 L), and one third is extracellular (16 L). Of the extracellular portion, two thirds is extravascular (10.5 L), and one third is intravascular (5.5 L). This approximation gives a good starting point when beginning to estimate fluid resuscitation, replacement, and maintenance.

2. The answer is C (Chapter 1, VII D). A pulmonary artery catheter can be useful in distinguishing cardiac dysfunction from other causes of shock in certain patients. It will allow the treating physician to measure left atrial filling pressure from the port in the tip via back pressure through the lungs. Cardiac output is measured via thermal dilution. Mixed venous oxygen saturation can be measured by drawing a sample from the catheter. Systemic vascular resistance can be calculated from the cardiac output, mean arterial pressure, and central venous pressure.

3. The answer is B (Chapter 1, III A ). The first mechanism activated when there is damage to a vessel is constriction, which is an effort to stop blood flow. This is followed by platelet activation, which produces a platelet plug. The intrinsic and extrinsic pathways are then activated to form a fibrin clot. The fibrinolytic system is the body's mechanism to dissolve established clots.

4. The answer is C (Chapter 1, II B ). Hypocalcemia can induce neuromuscular irritability, including perioral and extremity numbness. This can progress to carpopedal spasm and tetany. The most common cause of hypocalcemia is parathyroid surgery to treat hypercalcemia, resulting in rebound hypocalcemia.

5. The answer is D (Chapter 1, V C). The wound described is a contaminated wound due to the gross spill of contaminated material. A clean wound is one made through normal, antiseptically prepared skin and encounters no infected or colonized areas. A clean-contaminated wound is similar to a clean wound except that a contaminated or potentially contaminated area (e.g., bowel, bronchus, urinary tract), which has been prepared to the best of one's ability and presents minimal contamination, has been opened. An infected wound is one that already has an established infection present. Secondary is a type of wound closure and not a classification of a wound.

6. The answer is C (Chapter 1, VII D 2 b). The arterial line mean pressure is the most accurate and is the most physiologically useful measurement of blood pressure. It may be very accurate but often has limited clinical usefulness and must be used cautiously. Noninvasive blood pressures are not very accurate in critically ill patients. Noninvasive blood pressure measurements are notoriously high in hypotensive patients and low in hypertensive patients.

7. The answer is A (Chapter 1, V C, D 3; Chapter 2, I A 3). Delayed primary closure is appropriate for contaminated wounds, such as a ruptured appendix without abscess formation. Wound dehiscences are closed with retention sutures that include all layers, including the skin, because the fascial strength has been compromised. Infected wounds are packed open to heal by secondary intention, as with drainage of a diverticular abscess. Clean and clean-contaminated wounds can be closed primarily, as with incisional hernia repair (clean) and vagotomy/pyloroplasty (clean contaminated).

8. The answer is A (Chapter 3, VI C a). Intra -abdominal sepsis in a diabetic patient may be complicated by the development of ketoacidosis and dehydration. The patient presents with a condition that will likely require emergent surgical intervention. Initial management should be directed at restoration of the patient's circulating blood volume and optimization of his physiologic status prior to possible laparotomy. The serum glucose, electrolytes, and pH should be determined and abnormalities corrected. Measurement of hourly urine output will allow assessment of the adequacy of resuscitation. Abdominal radiographs should be obtained to look for free intraperitoneal air, and broad spectrum intravenous antibiotics should be administered, but fluid resuscitation takes top priority. A computed tomography scan may not be indicated in the patient who, on physical examination and history, clearly has peritonitis.

9. The answer is A (Chapter 2, VII D). Enterocutaneous fistulas typically respond to conservative management and spontaneously close when conditions are favorable. Octreotide has been shown to decrease pancreatic fistula output and clearly does not inhibit resolution. Distal obstruction (pancreatic duct stricture), infection, foreign body (nonabsorbable suture), and epithelialization all inhibit resolution.

10. The answer is C (Chapter, 3 II D; Table 3-5). In 1997, the American Heart Association updated guidelines to clarify recommendations for antibiotic prophylaxis for the prevention of bacterial endocarditis. In general, appropriate prophylaxis should be given to patients with underlying structural cardiac defects (e.g., prosthetic cardiac valves, significant valvular disease, hypertrophic cardiomyopathy, complex congenital heart disease, surgically constructed systemic-pulmonary shunts) who undergo procedures leading to bacteremia with organisms likely to cause endocarditis (e.g., major dental work or invasive procedures of the respiratory, gastrointestinal, or genitourinary tracts).

11. The answer is C (Chapter 3, III C). Major upper abdominal surgery performed via a vertical midline incision would be expected to have the greatest impact on postoperative pulmonary function. Other operative factors would include thoracotomy, residual intraperitoneal sepsis, age greater than 59 years, prolonged preoperative hospitalization, colorectal or gastroduodenal surgery, procedure longer than 3.5 hours, and higher body mass index. Lower abdominal and extremity surgery are associated with fewer pulmonary complications when compared with thoracic and upper abdominal surgery.

12. The answer is C (Chapter 3, C 1 b). Indications for emergent dialysis include life -threatening hyperkalemia, severe metabolic acidosis secondary to retained organic acids, uremic pericarditis, and volume overload. The serum creatinine and blood urea nitrogen levels reflect the underlying renal dysfunction but will not necessarily mandate emergent preoperative dialysis.

13. The answer is C (Chapter 3, I C; Table 3-1). Preoperative evaluation with routine coagulation studies is neither cost effective nor routinely indicated. Patients with a history of postsurgical bleeding or ongoing acute hemorrhage, patients on oral anticoagulation, patients with liver disease or hepatobiliary obstruction, malnourished patients, and patients unable to give an adequate history should have prothrombin time, partial thromboplastin time, and platelet counts checked preoperatively.

14–17. The answers are 14 -D, 15 -C, 16 -B, and 17 -A (Chapter 2, II A ; II A 1 b). Sump drains are needed to adequately decompress the stomach. When the pleural space requires drainage, a chest tube is placed and connected to an underwater seal so that air and fluid cannot reflux into the chest. This is needed because of the negative intrathoracic pressure generated with each inspiration. Diffuse peritonitis cannot be drained, as the peritoneal contents quickly “wall off” foreign bodies such as drains; discrete intraperitoneal collections can be drained. Splenectomy jeopardizes the pancreatic tail, which is in close proximity to the splenic hilum. When the area is obscured, as with the hematoma accompanying splenic rupture, the integrity of the pancreas cannot be assured, and the potential pancreatic fluid leak is drained with a closed-suction drain such as a Jackson -Pratt drain.

Chapter 4

Principles of Thoracic Surgery

D. Bruce Panasuk

William R. Alex

Richard N. Edie

I General Principles of Thoracic Surgery

A Anatomy of the thoracic cavity

Thechest wall (Fig. 4-1) is formed by the sternum, ribs, vertebral column, intercostal muscles, intercostal vessels (that run on the undersurface of the ribs), and nerves. Its inferior border is the diaphragm. It is lined internally by the parietal pleura.

The mediastinum (Fig. 4-2) is the anatomic region between the pleural cavities for the length of the thorax.

Theanterior compartment extends from the undersurface of the sternum to the pericardium and contains the thymus gland, lymph nodes, ascending and transverse aorta, and great veins.

Thevisceral compartment extends from the pericardium to the anterior longitudinal spinal ligament and and contains the pericardium, heart, trachea, hilar structures of the lung, esophagus, phrenic nerves, and lymph nodes.

Theparavertebral sulci are actually potential spaces that contain the sympathetic chains, intercostal nerves, and descending thoracic aorta.

Lungs and tracheobronchial tree (Fig. 4-3)

Theright lung has three lobes—the upper, middle, and lower—separated by two fissures.

The major (oblique) fissure separates the lower lobe from the upper and middle lobes.

The minor (horizontal) fissure separates the upper lobe from the middle lobe.

Theleft lung has two lobes—the upper and the lower. The lingula is a portion of the upper lobe. The lobes are separated by a single oblique fissure.

Bronchopulmonary segments are intact sections of each lobe that have a separate blood supply, allowing segmental resection. There are ten bronchopulmonary segments on the right and eight bronchopulmonary segments on the left.

Thetracheobronchial tree (see Chapter 5, IX A ) is formed from respiratory epithelium with reinforcing cartilaginous rings; the branching bronchial tubes are progressively smaller, down to a diameter of 1–2 mm.

The blood supply is dual.

Pulmonary artery blood is unoxygenated.

Bronchial artery blood is oxygenated.

Lymphatic vessels are present throughout the parenchyma and toward the hilar areas of the lungs.

FIGURE 4-2 The anatomic compartments of the mediastinum.

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FIGURE 4-3 Lungs and tracheobronchial tree. (Courtesy of Thomas C. King and Craig R. Smith. Columbia Presbyterian Hospital, New York.)

Endoscopy

Laryngoscopy is occasionally an important procedure when carcinoma of the lung is suspected. Tumor involvement of the recurrent laryngeal nerves (signifying inoperability) can be diagnosed via laryngoscopy when suspicion is raised by vocal cord paralysis with resultant hoarseness.

Bronchoscopy is useful in many diseases of the tracheobronchial tree for both diagnostic and therapeutic purposes.

Diagnostic uses

To confirm a lung or tracheobronchial tumor suggested by history, physical examination, or chest radiograph

To identify the source of hemoptysis

To obtain specimens for culture and cytologic examination from an area of persistent pulmonary atelectasis or pneumonitis

To obtain tissue biopsy

Therapeutic uses

To remove a foreign body

To remove retained secretions (e.g., after administration of general anesthesia or from aspiration of gastric contents)

To drain lung infections, such as abscesses

Types

Rigid bronchoscopy allows visualization of the trachea and main bronchi to the individual lobes.

It is excellent for biopsies of endobronchial lesions and for clearing of thick secretions and blood.

The performance of rigid bronchoscopy under local anesthesia requires considerable skill.

Flexible fiberoptic bronchoscopy is used more frequently.

It is particularly helpful for visualizing lobar bronchi and small bronchopulmonary segments and for the biopsy of lesions in that area.

Although not as effective as rigid bronchoscopy, it may also be used for clearing secretions.

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It is especially useful when the patient is intubated, allowing the bronchoscope to be introduced through the endotracheal tube, thus retaining the airway.

Specific advantages

Biopsy for suspicion of endobronchial or parenchymal tumor may be performed transbronchially via the bronchoscope in approximately one third of cases. Pneumothorax is a rare complication that occurs in fewer than 1% of cases.

Parenchymal biopsies are also useful if an infection is suspected. Infections, such as those caused by Pneumocystis carinii , can be diagnosed with fixed tissue specimens and may require biopsy.

Widening of the tracheal carina in patients with lung tumors can be seen on bronchoscopy. It suggests distortion of the tracheal anatomy by subcarinal nodes and is a poor prognostic sign.

Mediastinoscopy is a procedure in which a lighted hollow instrument is inserted behind the sternum at the tracheal notch and directed along the anterior surface of the trachea in the pretracheal space.

Diagnostic uses

Direct biopsy of paratracheal and subcarinal lymph nodes. Positive nodes may either indicate the need for preoperative chemotherapy or unresectability.

It is also useful for diagnosing other pulmonary problems, such as sarcoidosis, lymphoma, and various fungal infections.

Mortality rate is less than 0.1%.

Complications include hemorrhage, pneumothorax, and injury to the recurrent laryngeal nerves, although the incidence is extremely low.

Scalene node biopsy

The scalene node-bearing fat pad is located behind the clavicle in the region of the sternocleidomastoid muscle. This area should be palpated in patients suspected of having lung tumors and should be biopsied if nodes are palpable.

Tumor is found in 85% of patients with palpable nodes but in fewer than 5% of patients with nonpalpable nodes.

The scalene nodes are surrounded by important structures, including the pleura, subclavian vessels, thoracic and other large lymph ducts, and phrenic nerves. The main complications of scalene node biopsy result from injury to these structures (e.g., pneumothorax, hemorrhage, chyle leak, and diaphragmatic paralysis).

Diagnostic pleural procedures

Thoracentesis. Pleural effusions are examined for organisms in suspected infections and are examined cytologically in suspected malignancies. Positive cytologic findings prove a tumor to be