Lippincott's Anesthesia Review: 1001 Questions and Answers

Chapter 12. Thoracic Anesthesia

Deppu Ushakumari and Ashish Sinha

    1.   Which of the following is not a characteristic feature of asthma?

          A.   Chronic inflammatory changes in the submucosa of the airways

          B.   Airway hyper responsiveness

          C.   Reversible expiratory airflow obstruction

          D.   Elastase deficiency in the airways

    2.   A 55-year-old male presented to you with a pulmonary function test report, which shows an increase of FEV1 percent predicted of more than 12%, and an increase in FEV1 of greater than 0.2 L in response to bronchodilators. Which characteristic of his respiratory illness is depicted here?

          A.   Bronchial asthma—acute bronchodilator responsiveness

          B.   Chronic obstructive pulmonary disease (COPD)—variability in airflow obstruction

          C.   COPD—acute bronchodilator responsiveness

          D.   All the above are correct

    3.   Which of the following techniques is associated with a lower complication rate related to bronchospasm in the asthmatic population?

          A.   Regional anesthesia

          B.   General anesthesia—laryngeal mask airway (LMA)

          C.   General anesthesia—endotracheal tube (ETT)

          D.   Combined general and neuraxial anesthesia

    4.   A 22-year-old patient with a history of moderate persistent asthma on medium-dose inhaled corticosteroids and long-acting inhaled β-agonist presents for an emergency appendectomy. On clinical examination, he is actively wheezing, but maintaining an oxygen saturation of 99% on room air. Which of the following statements about this clinical scenario is most appropriate?

          A.   Presence of wheezing on physical examination indicates that he is having a severe attack of asthma

          B.   Volatile anesthetics cause bronchodilation through catecholamine-independent mechanisms

          C.   Increased airway resistance that occurs intraoperatively is usually due to acute exacerbation of asthma

          D.   A laryngeal mask airway (LMA) is more stimulating to the airway than an endotracheal tube, and should be avoided in asthmatics

    5.   During the above case, the end-tidal sevoflurane concentration reads 3.5, but the anesthesia ventilator is alarming because of high peak airway pressures. Which of the following is the most likely cause?

          A.   Acute bronchospasm

          B.   Anaphylactic reaction to intravenous muscle relaxant that you just administered

          C.   Mechanical causes of obstruction

          D.   Inadequate depth of anesthesia

    6.   At the end of the above case, the surgeon requests you to extubate the patient fully awake because he found extensive intestinal adhesions and is afraid of retained gastric contents in the stomach. Which of the following will be your most likely plan of action?

          A.   Insert an orogastric tube, empty the stomach as much as you can, and proceed with a deep extubation to avoid bronchospasm

          B.   Administer intravenous lidocaine to decrease the likelihood of airway stimulation and wait till the patient is fully awake before extubation

          C.   Shut off the inhalational agent and use intravenous propofol to avoid transitioning through a rocky stage-2 wake up

          D.   Transition to a laryngeal mask airway (LMA) under sevoflurane anesthesia and let the patient wake up with an LMA

    7.   Which of the following is true regarding administering general anesthesia to a chronic obstructive pulmonary disease (COPD) patient?

          A.   Nitrous oxide + opioid technique is ideal

          B.   Use large tidal volumes

          C.   Use lower breathing rates to permit more exhalation time

          D.   Correct the hypercapnia intraoperatively to help extubate early

    8.   Anesthetic considerations for a patient with severe pulmonary hypertension include all the following, except

          A.   Right heart catheterization is the gold standard for diagnosis

          B.   Mortality in pregnant patients undergoing vaginal delivery is very small as opposed to cesarean section

          C.   Minimize tachycardia, hypoxemia, and hypercapnia during anesthetic management

          D.   Cardiac output from a failing right ventricle depends on filling pressure from venous return and pulmonary pressure

    9.   Which of the following is not a part of the “STOP BANG” screening questionnaire for obstructive sleep apnea (OSA)?

          A.   Snoring

          B.   Observed apnea

          C.   Exercise tolerance

          D.   High blood pressure

  10.   Risk factors associated with increased perioperative morbidity and mortality in thoracic surgery patients include all the following, except

          A.   Extent of lung resection

          B.   Age older than 70 years

          C.   Experience of the operating surgeon

          D.   Male sex

  11.   The following is not necessarily a part of prethoracotomy respiratory assessment

          A.   Pulmonary capillary wedge pressure >18 mm Hg

          B.   Predicted postoperative FEV1 >40%

          C.   VO2 max >15 mL/kg/min

          D.   Predicted postoperative diffusing capacity for carbon monoxide (DLCO) >40%

  12.   Which of the following is one of the benefits regarding cessation of smoking 12 to 24 hours prior to surgery?

          A.   Shift of oxyhemoglobin dissociation curve to the right

          B.   Improvement in mucociliary transport

          C.   Decrease in sputum production

          D.   Improved small-airway function

  13.   In surgical cases requiring lung isolation

          A.   Measurement of tracheal width from a posteroanterior chest radiograph is of no use in selecting the size of a double-lumen tube (DLT)

          B.   More frequent use of left-sided DLT is based on the anatomy of tracheobronchial tree

          C.   Uniform ventilation to all lobes is most likely achieved by a right-sided DLT because it has a ventilation slot in the bronchial tube

          D.   Fiber–optic confirmation of correct DLT placement is not required if you have good clinical confirmation

  14.   A 59-year-old lady is intubated with a 37 left-sided double-lumen tube (DLT) for wedge resection of left lower lobe nodule. After intubation, you inflate the bronchial cuff and ventilate the left lung through the bronchial lumen without any difficulty. Then you proceed to inflate the tracheal cuff and ventilate through the tracheal lumen. You notice a very high resistance to air flow. Which of the following events is most unlikely with the said clinical picture?

          A.   Left DLT too deep with the tracheal outlet into the left main-stem bronchus

          B.   Left DLT displaced with the bronchial cuff herniated at carina

          C.   Left DLT entered the right bronchus with the tracheal outlet in the right main stem

          D.   DLT too far out with the bronchial lumen sitting just above the carina

  15.   What would you do if you have the following situation with a bronchial blocker for left lung surgery?

images

Figure 12-1.

          A.   Appropriate positioning for this surgery

          B.   Withdraw the bronchial blocker a couple of centimeters

          C.   Insert the bronchial blocker a few centimeters farther down

          D.   Remove the bronchial blocker and reinsert it into the left side

  16.   In which of the following situations is applying continuous positive-airway pressure (CPAP) to the nondependent lung most ideal for improving oxygenation?

          A.   Bronchopleural fistula

          B.   Open lobectomy

          C.   Massive pulmonary hemorrhage

          D.   Sleeve resection

  17.   Which of the following statements is false regarding ventilation/perfusion relationship in a lateral decubitus position during spontaneous ventilation?

          A.   The ventilation/perfusion matching is preserved

          B.   Contraction of dependent hemi diaphragm is more efficient

          C.   Dependent lung is on a more favorable part of the compliance curve

          D.   The lower lung receives less ventilation and more perfusion than the upper lung

  18.   In an open pneumothorax, the major effect of mediastinal shift is to

          A.   Decrease the contribution of dependent lung to the tidal volume

          B.   Move air to and fro between the dependent and the nondependent lung

          C.   Decrease the perfusion to the dependent lung

          D.   Compress the big veins and decrease cardiac preload

  19.   Factors known to inhibit hypoxic pulmonary vasoconstriction (HPV) and thus worsen the alveolar–arterial oxygen gradient include all of the following, except

          A.   Hypocapnia

          B.   Nitroglycerin

          C.   Hypercapnia

          D.   Pulmonary infection

  20.   A 64-year-old female is undergoing a left video-assisted thoracoscopy for a suspicious pulmonary nodule. Immediately after positioning the patient laterally, which of the following alarms indicates a malposition of the double-lumen tube (DLT)?

          A.   High CO2 alarm

          B.   Low O2 alarm

          C.   Low tidal volume alarm

          D.   Unable to drive bellows alarm

  21.   A bronchial blocker is useful in all of the following clinical situations, except

          A.   Patient to be left intubated post operatively

          B.   Anatomical abnormality precluding the placement of a double-lumen tube (DLT)

          C.   Tamponading bronchial bleeding in adult patients

          D.   To attain better collapse of the nondependent lung

  22.   Which of the following statements about lung resection surgery is false?

          A.   Mortality rate for pneumonectomy is 5% to 7%

          B.   Mortality rate for lobectomy is 2% to 3%

          C.   Mortality is higher for left-sided pneumonectomy

          D.   Most postoperative deaths result from cardiac issues

  23.   Regarding lung resection surgery, which of the following statements is false?

          A.   Perioperative arrhythmias are common

          B.   Supraventricular tachycardias (SVTs) are thought to result from surgical manipulation or distension of the right atrium

          C.   Incidence of arrhythmia decreases with age due to the ageing of cardiac conduction system

          D.   Postoperative hypoxemia and acidosis due to atelectasis and shallow breathing are common

  24.   Which of the following has the least effect on hypoxic pulmonary vasoconstriction (HPV)?

A.   Nitrous oxide

 

B.   Desflurane

end tidal 5.5%

C.   Sevoflurane

end tidal 2.5%

D.   Isoflurane

end tidal 1.5%

  25.   Which of the following statements is not true regarding “lower lung syndrome”?

          A.   It is caused by excessive fluid administration in a lateral decubitus position

          B.   It increases intrapulmonary shunting

          C.   It is gravity-dependent transudation of fluid into the dependent lung

          D.   It is due to volutrauma caused during one-lung ventilation

  26.   The first step recommended to improve oxygenation if a patient is exhibiting drop in oxygen saturation during one-lung ventilation is

          A.   Apply continuous positive-airway pressure (CPAP) to the collapsed lung

          B.   Apply positive end–expiratory pressure (PEEP) to the dependent lung

          C.   Periodic inflation of the collapsed lung

          D.   Continuous inflation of oxygen into collapsed lung

  27.   During apneic oxygenation,

          A.   Adequate oxygenation can be maintained only for short periods of time

          B.   Arterial PCO2 rises 3 to 4 mm Hg in the first minute

          C.   Arterial PCO2 rises 1 to 2 mm Hg each subsequent minute after the first minute

          D.   Progressive respiratory acidosis limits the use of this technique to 10 to 20 minutes in most patients

  28.   A 68-year-old male patient with a lung nodule underwent a right upper lobectomy. On postoperative day 4, the patient develops a sudden large air leak from the chest tube associated with increasing pneumothorax and partial lung collapse. The most likely cause is

          A.   Bronchopleural fistula on the right from necrosis of suture line

          B.   Bronchopleural fistula on the right from inadequate surgical closure of the bronchial stump

          C.   Atelectasis causing shifting of the mediastinum to the left

          D.   A normal finding

  29.   An 80-year-old female underwent a left lower lobectomy. In the ICU on postoperative day 2, she develops hemoptysis. The vital signs are stable, but on the chest X-ray a homogenous density is seen in the left lower lung area. After subsequent bronchoscopy, the left upper lobar orifice is closed. The most likely diagnosis is

          A.   Acute herniation of the heart into the left lower lobe area

          B.   It is a normal finding and the homogenous opacity is due to accumulation of fluid in the left lower lobe area

          C.   Torsion of the left upper lobe as the left upper lobe expanded to occupy the left hemithorax

          D.   Reexpansion edema of the left upper lobe

  30.   A 45-year-old recent immigrant from Vietnam is admitted to the emergency department with massive hemoptysis (>600 mL in the last 24 hours). You are called to evaluate the patient for a possible bronchial artery embolization or a rigid bronchoscopy. In your discussion with the patient, which of the following statements is not appropriate about his clinical condition?

          A.   Operative mortality exceeds 20%

          B.   It can be done as a semi-elective procedure, and there is no need to do it emergently

          C.   The most common cause of death is asphyxia secondary to blood in the airway

          D.   Medical management has a lower mortality rate than operative management

  31.   An 81-year-old chronic smoker, with a history of 60 pack year smoking, is admitted with progressive dyspnea and a huge right-sided pulmonary cyst. The cyst is compressing her remaining right lung, and she is brought to the OR for an emergency pulmonary cystectomy. Which of the following is right regarding anesthetic management of this patient?

          A.   The greatest risk of rupture of the cavity is during preoxygenation just prior to induction

          B.   These cavities allow to and fro movement of air and have a very low chance to progressively enlarge

          C.   Maintenance of spontaneous ventilation is desirable until a double-lumen tube (DLT) is in place

          D.   Assisted ventilation is not necessary immediately after induction and can be harmful

  32.   A 66-year-old patient with a history of severe tracheal stenosis is presenting for a tracheal resection. The most unlikely clinical finding is

          A.   Progressive dyspnea

          B.   Wheezing evident on exertion

          C.   Dyspnea worse on sitting up and leaning forward

          D.   Patient may have a history of blunt/penetrating tracheal trauma

  33.   In the anesthetic management of the above patient, which of the following statements is correct?

          A.   Flow–volume loops aid the clinician in evaluating the severity of the lesion

          B.   Right radial artery blood pressure monitoring is preferred over the left side for lower tracheal resection

          C.   Slow-inhalation induction is not advisable and a rapid-sequence induction should be used

          D.   Early extubation is not advisable at the end of the procedure for risk of rupturing the suture lines

  34.   Complications associated with mediastinoscopy include all the following, except

          A.   Vagally mediated reflex bradycardia

          B.   Cerebral ischemia

          C.   Pneumothorax

          D.   Thoracic duct injury

  35.   Anesthetic considerations for bronchoalveolar lavage include all the following, except

          A.   It is performed for patients who make excess quantities of surfactant and fail to clear it

          B.   It is performed under general anesthesia with lung isolation

          C.   It is usually performed in the supine position

          D.   It involves positioning the patient in a lateral position to aid active suctioning of the lavage fluid

  36.   Considerations for lung transplantation include all the following, except

          A.   Cor pulmonale does not necessarily require combined heart–lung transplantation

          B.   Patients with diminished left-ventricular function can be transplanted as long as they have normal right-ventricular function

          C.   Patients with Eisenmenger syndrome require combined heart–lung transplantation

          D.   Organ selection is based on size and ABO compatibility

  37.   After a double-lung transplantation

          A.   Loss of lymphatic drainage predisposes to pulmonary edema

          B.   Respiratory pattern changes to a slow deep respiration

          C.   Cough reflex is abolished above the carina

          D.   Hypoxic pulmonary vasoconstriction is abolished

  38.   Anesthetic considerations for esophageal surgery include

          A.   Very low risk of pulmonary aspiration

          B.   Mandatory pulmonary artery catheter monitoring

          C.   Diaphragmatic retractors interfering with cardiac function

          D.   Always performed with a double-lumen tube (DLT)

  39.   Lung-volume-reduction surgery (LVRS)

          A.   Has been demonstrated to have very good efficacy by the National Emphysema Treatment Trial (NETT)

          B.   Necessitates limiting of peak inspiratory pressure to 30 cm H2O following intubation

          C.   A prolonged inspiratory time is recommended for facilitating exposure of the surgical segments

          D.   Patients have a better outcome if kept intubated at the end of the surgery

  40.   Which of the following flow–volume loops will be expected in a child with variable extrathoracic obstruction?

images

Figure 12-2.

  41.   A 12-year-old boy with suspected lymphoma presents to you for a lymph node biopsy. When you go to visit the patient, you notice that he has venous engorgement and edema of the head, neck, and arms. He refuses to lie down, and is tachycardiac and tachypneic. The preferred management for this boy would be

          A.   Safest thing will be to secure the airway immediately by using rapid-sequence induction

          B.   Preferably biopsy the lymph node under local anesthesia so that the patient can be sent for radiotherapy immediately after a tissue diagnosis

          C.   Empiric treatment with steroids and surgery under general anesthesia only after the airway compromise is alleviated

          D.   Get a chest X-ray and rule out mediastinal compression prior to any active management

CHAPTER 12 ANSWERS

   1.    D.   Asthma is a type of reactive airway disease characterized by hyperresponsive airways, reversible expiratory airflow obstruction, and chronic inflammation. Sudden bronchospasm in response to external/internal stimuli and response to bronchodilators like β2-agonists are important distinguishing features of asthma. Elastase deficiency in the airways is a feature of emphysema.

   2.    A.   Response to a bronchodilator drug resulting in relief of airway obstruction is highly suggestive of bronchial asthma. A more than 12% increase in predicted FEV1 and an absolute increase in FEV1 of more than 0.2 L suggest acute bronchodilator responsiveness and variability in airflow obstruction. The reversibility of this magnitude is almost always indicative of bronchial asthma. COPD patients do respond to bronchodilators but not to the same extent. Early stages of asthma are diagnosed by decreased mid expiratory flow rates (effort independent) and decreased FEV1 and by its reversibility.

   3.    A.   In a severely asthmatic patient, regional anesthesia is superior to general anesthesia with an LMA, which is better than general anesthesia with ETT. The choice of anesthetic technique is often influenced by the severity of asthma, history of previous intubations for asthma, dependence on inhaled bronchodilators, and patient preference. The goal in any such circumstance is to decrease airway manipulation and stimulation. If a general anesthetic technique is pursued, inhaled bronchodilator therapy immediately prior to induction, use of non–histamine-releasing drugs, airway manipulation only after deep anesthetic plane, and use of intravenous lidocaine prior to intubation have all been proven to be useful.

   4.    B.   History and physical examination can suggest presence of severe asthma if the patient has had repeated intubations for asthma. Even though high-pitched, musical wheezes are characteristic of asthma, they are not specific and they have no correlation with the severity of obstruction. Spirometry is the only objective method to quantify the severity of obstruction. Sudden severe bronchospasm can present as high airway pressures with absence of breath sounds and very high resistance to mechanical ventilation. Mechanical causes of obstruction such as a kinked endotracheal tube or a mucous plug can also present a similar clinical picture and are more common. If bronchospasm is suspected, anesthesia should be augmented with an intravenous anesthetic such as propofol. General anesthesia through a LMA is less stimulating to the airway than through an endotracheal tube. Volatile anesthetics are potent bronchodilators, and they act through catecholamine-independent mechanisms. They are rarely used as second-line agents in cases of bronchospasm refractory to medical therapy.

   5.    C.   Acute bronchospasm causes expiratory wheezing, increased peak inspiratory pressure or decreased tidal volume (depending on the mode of ventilation), and a characteristic upslope of the capnogram. Any airway stimulation can cause severe reflex bronchoconstriction and bronchospasm in severely asthmatic patients with hyperactive airways. Mechanical causes of obstruction such as a kinked endotracheal tube or a mucous plug can also present a similar clinical picture and are more common. When troubleshooting such a scenario, an intravenous anesthetic agent is very helpful to deepen the plane of anesthesia as the delivery of inhaled anesthetic agents may not be effective.

   6.    B.   A patient who has adequate return of neuromuscular function and has a regular spontaneous breathing pattern with adequate tidal volumes can be considered a candidate for deep extubation. After clearing out the secretions from the oropharynx and the endotracheal tube, extubation is performed under a deep plane of anesthesia and ventilation continued by a mask/LMA. Careful patient selection is very important, and it should not be considered in those at increased risk for aspiration of gastric content and if the necessary airway management skills are not immediately available. When extubation is delayed for reasons of patient safety, (presence of gastric contents in a case with acute appendicitis), intravenous administration of lidocaine (1.5–2 mg/kg bolus) may decrease the likelihood of airway irritation and bronchospasm. Thus, extubation can be performed after the patient is awake and following commands if airway irritation can be avoided.

   7.    C.   Balanced anesthesia using an inhaled anesthetic and opioid is a safe choice for anesthesia for a COPD patient. Use of nitrous oxide (N2O) is normally safe but not strictly necessary. The ability of N2O to diffuse into closed air spaces may lead to the enlargement of an emphysematous bulla or a pneumothorax and possibly rupture. Air trapping and development of auto positive end–expiratory pressure can be decreased by providing a prolonged expiratory time. This can be done by using a normal tidal volume and a slow respiratory rate and an I:E ratio of ≥1:3. Care should be taken to avoid hyperventilation and creation of a respiratory alkalosis as these patients tolerate marked hypercapnia secondary to hypoventilation. However, high PaCO2 levels will increase pulmonary artery pressure, which may be poorly tolerated in patients with a compromised right-ventricular function and cor pulmonale. Bronchodilation using inhaled β2-agonists and pulmonary toilet through blind suctioning or fiberoptic bronchoscopy may facilitate safe extubation of the trachea.

   8.    B.   Pulmonary hypertension is defined as an increase in mean pulmonary artery pressure above 25 mm Hg at rest or 30 mm Hg with exercise in the presence or absence of an elevated pulmonary capillary wedge pressure. Right-sided heart catheterization is the gold standard for diagnosing and quantifying the degree of pulmonary hypertension. Care should be taken to avoid all the factors that increase pulmonary vascular resistance in a patient with severe pulmonary hypertension presenting for surgery. This includes avoiding hypoxia, hypercarbia, hypothermia, light anesthesia, pain, dysrhythmias, and maintaining adequate cardiac output. Progressive right-ventricular dilation and hypertrophy in response to an increased afterload generated by chronic pulmonary hypertension will eventually lead to right-ventricular systolic dysfunction, inadequate left-ventricular filling, and eventually biventricular failure. The interventricular septal bulge decreases left-ventricular cavity filling, further worsening the left-ventricular failure. Cardiac output from a failing right ventricle depends on the filling pressure from venous return and pulmonary pressure. Pulmonary hypertension in pregnant patients has a high mortality rate up to 50% for vaginal delivery and even higher for cesarean delivery.

   9.    C.   Snoring, daytime sleepiness, hypertension, obesity, and a family history of OSA are risk factors for OSA. There is a high risk for OSA if >3 yes to the below questions.

          S (snore) Have you been told that you snore?

          T (tired) Are you often tired during the day?

          O (obstruction) Do you know if you stop breathing or has anyone witnessed you stop breathing while you are asleep?

          P (pressure) Do you have high blood pressure or on medication to control high blood pressure?

          B (BMI) Is your body mass index greater than 28?

          A (age) Are you 50 years old or older?

          N (neck) Are you a male with a neck circumference greater than 17 inches, or a female with a neck circumference greater than 16 inches.

          G (gender) Are you a male?

  10.   D.    The extent of lung resection (pneumonectomy > lobectomy > wedge resection), age older than 70 years, and inexperience of the operating surgeon are risk factors associated with increased perioperative morbidity and mortality rates. In patients with anatomically resectable lung cancer, pulmonary function tests—ppoFEV1, lung perfusion scanning, and exercise testing to measure maximum oxygen consumption (VO2max)—may predict postoperative pulmonary function and outcome.

  11.   A.    The prethoracotomy respiratory assessment has been labeled as a three-legged stool that incorporates assessment of respiratory mechanics, cardiopulmonary reserve, and lung parenchymal function. The following findings are considered favorable: respiratory mechanics assessment demonstrates ppoFEV1 >40%, MVV, RV/TLC, and FVC; the cardiopulmonary reserve measurements show VO2 max >15 mL/kg/min, 6-minute walk test, exercise SpO2 <4%, stair climb >2 flights, and assessment of lung parenchymal function shows ppoDLCO >40%, PaO2 >60, PaCO2 <45 mm Hg. The choices B, C, and D are the most valid tests out of the “three-legged stool.”

  12.   A.    Any patient presenting for elective surgeries with a history of smoking should be advised smoking cessation regardless of the time available prior to surgery. Smoking can affect the pulmonary system in multiple ways—increase in airway irritability and secretions, decreased mucociliary transport, and increased incidence of postoperative pulmonary complications. Patients are more receptive toward interventions immediately prior to surgery and this provides a good teachable moment. Prolonged abstinence (8–12 weeks) is required to improve mucociliary transport and small-airway function and decrease sputum production. The incidence of postoperative pulmonary complications decreases with abstinence from cigarette smoking for more than 8 weeks in patients undergoing coronary artery bypass surgery, and more than 4 weeks in patients undergoing pulmonary surgery. However, even 12 to 24 hours of cessation may be beneficial because it decreases the level of carboxyhemoglobin and it shifts the oxyhemoglobin dissociation curve to the right.

  13.   B.    The angle between the right main bronchus and trachea is 25 degrees at the level of carina, but the left main bronchus takes off at an acute angle of 45 degrees. Thus, right main bronchus is shorter, wider, and more in line with the trachea. There is a good correlation between tracheal and bronchial width (bronchial diameter is predicted to be 0.68 of tracheal diameter).

             The right upper lobe bronchus takes off at an acute angle from the point of origin of the right primary bronchus and is easily occluded if the ventilation port on the right-sided DLT is not aligned properly. Because of these reasons, a left-sided DLT is most commonly used. Uniform ventilation to all lobes can be achieved more easily with a left-sided DLT than a right-sided one. Measurement of tracheal width from a posteroanterior chest roentgenogram can help select the size of a left-sided DLT. In addition to physical examination, fiberoptic assessment should be done to confirm proper position of a left-sided DLT because the malposition incidence if confirmed with auscultation alone is considered to be 20% to 48%.

  14.   C.    There is no single predictor that can accurately predict the appropriate size of a DLT. But a general guideline is a woman shorter than 160 cm should be intubated with a 35-Fr tube, a woman taller than 160 cm should be intubated with a 37-Fr tube, and a man shorter than 170 cm should be intubated with a 39-Fr tube, and a man taller than 170 cm should be intubated with a 41-Fr tube. This tube size of 37 Fr may be too big for this lady. When we inflated the bronchial cuff and attempted ventilation, the unoccluded outflow tract of the bronchial lumen made it easy to ventilate. However, after inflating the tracheal cuff (with the bronchial cuff already inflated), failure to ventilate suggests that something is occluding the tracheal lumen (the bronchial cuff in this situation). The presence of breath sounds only on the right side with both the cuffs inflated suggests that the bronchial lumen is patent and ventilating the right side. The ventilated gas coming out of tracheal lumen is being trapped between the tracheal and the bronchial balloons. This finding can be confirmed with fiberoptic bronchoscopy, and the tube needs to be repositioned with bronchial cuff in the left main-stem bronchus. If with the same clinical picture, you are hearing breath sounds only on the left side with both the cuffs inflated, it could be that the DLT is too far into the left bronchus with the tracheal lumen opening into the left main stem. It is also possible that the bronchial cuff is barely into the left main stem with a herniated bronchial cuff preventing the inflation of right-sided lung via the tracheal lumen.

images

Figure 12-3.

  15.   B.   Figure 12-4A is a bronchial blocker for a left-sided lung surgery placed deeply into the left main-stem bronchus. Figure 12-4B is a bronchial blocker advanced too far into the right main stem, and the balloon of the bronchial blocker is occluding the right upper lobe takeoff. For both situations, the bronchial blocker should be withdrawn a couple of centimeters to a level just below the carina.

images

Figure 12-4.

images

Figure 12-4.

  16.   B.    Difficulties with oxygenation are fairly common during one-lung ventilation. If the SpO2 is below acceptable range, various techniques that can be tried to improve the oxygenation include increasing FIO2 to 1, intermittent two-lung ventilation, applying positive end–expiratory pressure (PEEP) to the dependent lung. However, the most effective method is the application of 5 to 10 cm H2O CPAP to the nondependent lung. This should be done prior to application of PEEP to the dependent lung. This low level of CPAP results in minimal lung inflation and generally does not interfere with surgery. A slow inflation of 2 L/min of oxygen into the nonventilated lung for 2 seconds and repeated every 10 seconds for 5 minutes or until the saturation rises to 98% has been shown to improve oxygenation during one-lung ventilation. CPAP applied to the operative lung may be disadvantageous in some cases like thoracoscopy, bronchopleural fistula, sleeve resection, or massive pulmonary hemorrhage.

  17.   D.    During spontaneous ventilation in lateral decubitus position, ventilation/perfusion matching is preserved because the lower lung receives more perfusion due to gravity and more ventilation due to better contraction of the dependent hemidiaphragm. The dependent hemidiaphragm gets a better displacement from a higher position in the chest. The dependent lung has a better compliance as well—this improves ventilation.

images

Figure 12-5.

  18.   A.    Inspiration in a lateral position during spontaneous ventilation causes more negative pleural pressure on the dependent side of the open pneumothorax. The relatively higher pressure on the nondependent side causes a downward shift of the mediastinum during inspiration. The reverse happens on expiration, and the mediastinum shifts upward. This results in an ineffective respiratory exchange, but the major effect is by decreasing the contribution of the dependent lung to the tidal volume.

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Figure 12-6.

  19.   C.    HPV is a protective mechanism by which body shunts away blood from a nonventilated lung. It plays a significant role in maintaining oxygenation during one-lung ventilation. Factors inhibiting HPV include infection, pulmonary hyper/hypotension, low PaCO2, changes in SvO2 (mixed venous oxygen saturation), and pharmacological agents like vasodilators—nitroglycerin and nitroprusside, β-agonists, calcium channel blockers, and inhalational anesthetic agents.

  20.   C.    Left-sided DLTs are most commonly used in clinical practice. Any change in position of the patient after the DLTs have been placed includes a risk of malpositioning of the DLT. Low exhaled tidal volumes and poor lung compliance are the most common initial indicators. Left-sided DLT may be malpositioned back into the trachea, into the right main-stem bronchus, or too far into the left primary bronchus. If it is in the trachea, the inflated bronchial cuff is preventing any ventilated gas from going past it. If it is in the right side or pushed too far into the left bronchus, the bronchial cuff may be obstructing the left upper or left lower lobe bronchus. These two situations can be immediately relieved by deflating the bronchial cuff.

  21.   D.    DLTs are considered to be the best lung isolation device currently in use. In certain situations, placement of a DLT is difficult and bronchial blockers are used for lung isolation. They are similar to Fogarty catheters and are single-lumen devices with an inflatable balloon at the tip. They are passed through a single-lumen endotracheal tube under fiberoptic guidance and the balloon is inflated within the bronchus of the operative side. The cuff of the bronchial blocker is a high-pressure–low-volume cuff. The single narrow lumen within the blocker allows the lung to deflate (though slowly) and can be used for suctioning or insufflating oxygen (below). The biggest problem is caused by the small size of the channel, which impairs exhalation. However, in patients with a history of difficult intubation bronchial blockers circumvent the need to reintubate a patient prior to transferring out of the operating room.

  22.   C.    The mortality rate for pneumonectomy is about 5% to 7%, compared with 2% to 3% for a lobectomy. Mortality is higher for right-sided pneumonectomy than for left-sided pneumonectomy. This is attributed to the greater loss of lung tissue. Lung cancer resection surgeries involve finding the right balance between resecting enough lung tissue to obtain a tumor-free margin, at the same time leaving enough for residual postoperative pulmonary function. Wedge resections for peripheral lesions, lobectomy for bigger tumors, pneumonectomy for tumors involving the main bronchus, sleeve resections for patients with proximal lesions, and limited pulmonary reserve are among the various choices the surgeons can make.

  23.   C.    The incidence of arrhythmias increases with age and with the amount of pulmonary resection. Perioperative arrhythmias are fairly common after thoracic surgery—atrial fibrillations/SVTs and PVCs are all seen and are thought to be a result of the surgical manipulation of the heart and distension of the right atrium as a result of decreased pulmonary vascular bed. Pulmonary complications after surgery can be decreased by preoperative incentive spirometry, bronchodilator therapy, and good pulmonary hygiene.

  24.   B.    Halogenated agents generally have minimal effects on HPV in doses <1 minimum alveolar concentration (MAC). Balanced anesthetic technique using a combination of inhaled anesthetic agents and intravenous opioids is beneficial. Inhalational agents allow delivery of 100% oxygen, are potent bronchodilators, and can be easily titrated to desired concentration and opioids have minimal hemodynamic effects as well as providing analgesia. They complement each other very well. However, use of long-acting opioids should be limited during surgery to prevent excessive postoperative respiratory depression. The only choice with <1MAC is B.

  25.   D.    Anesthetic management of pulmonary resections includes very tight fluid management. Most of the time restrictive fluid management strategy facilitated by use of blood/colloids is entertained. Lower lung syndrome refers to gravity-dependent transudation of fluid into the dependent lung, which decreases effective oxygenation, increases ventilation–perfusion mismatch, shunting, and promotes hypoxemia. This transudation is worsened by excessive administration of intravenous crystalloids. On the nondependent side, reexpansion of the collapsed lung can result in pulmonary edema due to alteration in the pressures on either side of the Starling equation.

  26.   A.    Hypoxemia is fairly common after institution of one-lung ventilation in the lateral position. Various interventions can be tried when it happens—some have better efficacy than the others. These include periodic reinflation of the collapsed lung with oxygen, which interferes with surgery; early ligation or clamping of the ipsilateral pulmonary artery—seldom used but can be tried in pneumonectomies; and CPAP (5–10 cm H2O) to the collapsed lung causing partial reexpansion of the lung and may interfere with surgery. The mechanism of action of CPAP application is supposed to oxygenation as well as displacement of blood from the pulmonary vasculature into the dependent lung. Other less efficacious methods that can be tried include PEEP (5–10 cm H2O) to the ventilated lung, oxygen insufflation to collapsed lung (diffusion respiration), and change in dependent lung minute ventilation (Vt 5 mL/kg is usually recommended but can be increased). Application of CPAP to the collapsed lung should be done before instituting PEEP to the ventilated lung, as the effect of PEEP depends on where the lung falls on the PEEP–PVR curve. Persistent hypoxemia requires immediate return to two-lung ventilation.

  27.   D.    Apneic oxygenation refers to insufflation of 100% oxygen at a rate greater than the oxygen consumption (>250 mL/min) while the ventilation is stopped. Progressive respiratory acidosis limits the use of this technique to 10 to 20 minutes in most patients. Oxygenation can be maintained in patients with normal DLCO for more than this time interval. During apneic oxygenation, arterial PCO2 rises 6 mm Hg in the first minute followed by 3 to 4 mm Hg every subsequent minute.

  28.   A.    Bronchopleural fistula refers to a communication between the bronchial and pleural spaces. It presents as a sudden large air leak from the chest tube that may be associated with an increasing pneumothorax and partial lung collapse. Inadequate surgical closure of the bronchial stump usually presents itself with a bronchopleural fistula in the first 24 to 72 hours. Necrosis of the suture line (bronchial/parenchymal) caused by ischemia or infection usually presents after 72 hours. This is a rare complication, but small air leaks are fairly common after segmental or lobar resection due to collateral ventilation from small channels at the sites of incomplete fissures. They are usually smaller in volume, will not cause significant impairment of ventilation, and will close by itself after a few days—after which chest tubes can be discontinued.

  29.   C.    This is the classical picture of torsion of a lung lobe as it expands to fill up the space left by resection of the other lobe. This is because the torsion results in occlusion of the pulmonary vein, which drains blood flow to that part of the lung and presents clinically as hemoptysis and radiographically as an enlarging homogenous density. This can be confirmed by visualizing a closed lobar orifice on bronchoscopy. On the other hand, an acute herniation of the heart into the operative hemithorax is associated with hemodynamic changes and a shift in the cardiac shadow on chest X-ray. This is caused by a large pressure difference between the two hemithoraces. Herniation to the right causes severe hypotension and an elevated central venous pressure due to torsion of the vena cava. Herniation to the left causes compression of the heart at the atrioventricular groove, resulting in hypotension, ischemia, and infarction.

  30.   D.    With the given history, the massive hemoptysis (defined as >500–600 mL of blood loss in 24 hours) is most likely infectious in origin with tuberculosis being a strong possibility. The other causes of massive hemoptysis include bronchiectasis, aspergillomas, neoplasms, foreign body in the trachea, and trauma. A potentially lethal hemoptysis with severe hemodynamic compromise necessitates emergency surgery. Bronchial artery embolization may be attempted if the patient is hemodynamically stable. Whenever possible, surgery is carried out in a semi-elective way, but the operative mortality is still high, >20%. However, medical management is associated with a much higher mortality, >50%. The most common cause of death is asphyxia secondary to blood in the airway.

  31.   C.    Pulmonary cysts or bullae are large cavitary lesions that behave as if they have a one-way valve, gets progressively large and may compress the remaining lung tissue. They may also rupture producing a tension pneumothorax. They can be congenital or acquired as a result of emphysema. They are usually scheduled for lung resection surgeries when they cause recurrent pneumothorax or progressive dyspnea. Positive-pressure ventilation results in further expansion of such cavities and increased risk of rupture along with impaired oxygenation from the affected lung. Maintenance of spontaneous ventilation (negative inspiratory pressure) is recommended until the affected lung is isolated using a DLT or until a chest tune is placed. Inhalational agents can be used to facilitate this, but the large dead space caused by the presence of huge cyst may result in progressive hypercarbia. Assisted ventilation is helpful in such circumstances. Care should be taken to avoid complete positive-pressure ventilation.

  32.   C.    Tracheal stenosis is narrowing of the airway as a result of tracheal mucosal damage followed by scarring. It can also be caused by tumors—squamous or adenoid cystic carcinoma. The inciting factors for the mucosal damage include trauma or prolonged endotracheal intubation. These patients present with progressive dyspnea, hemoptysis, and stridor on exertion. The dyspnea is characteristically worse on lying down and is made better by sitting up and leaning forward.

  33.   A.    Anesthetic considerations for tracheal resection include invasive monitoring, use of anticholinergics to prevent increased secretions, slow inhalational induction maintaining spontaneous ventilation, airway stimulation after attaining a deep plane of anesthesia, return of spontaneous ventilation, and early extubation. The left radial artery is preferred for lower tracheal resections because of the potential for compression of the innominate artery. A nonirritating inhalational agent like sevoflurane in 100% oxygen can be used along with short-acting opioids like remifentanil. Care should be taken to decrease the FIO2 to below 0.3 if the surgeon is using laser to resect the scar tissue. After opening the stenosed segment, the surgeon can insert a sterile endotracheal tube into the segment of trachea below the lesion and patient can be ventilated through that. There will be a brief period of apnea as the surgeon is anastomosing the anterior part of trachea after resection. Once the anastomosis is complete, the initial endotracheal tube can be readvanced below the lesion. The neck is kept flexed in the postoperative period to minimize tension on the tracheal suture line. Heliox offers a method to avoid turbulence due to its lower density. Flow–volume loops confirm the location of the obstruction and aid the clinician in evaluating the severity of the lesion.

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Figure 12-7.

  34.   D.    Mediastinoscopy involves operating on an area covered with blood vessels and nerves. The complications include reflex bradycardia due to vagal stimulation, bleeding from damage to the great vessels, pneumothorax, air embolism, post-op hoarseness due to recurrent laryngeal nerve injury, and phrenic nerve injury. A false drop in blood pressure may be observed due to compression of the innominate artery if the arterial line is placed on the right arm. A spontaneously breathing patient with head end elevated is also at risk for a pneumothorax that presents postoperatively.

  35.   D.    Pulmonary alveolar proteinosis is a condition in which patients produce excessive quantities of surfactant and fail to clear it, producing bilateral lung involvement and recurrent pneumonias. Bronchoalveolar lavage is performed in these patients for severe hypoxemia or worsening dyspnea. They undergo sequential lung lavages interspaced by a few days with the worse lung getting lavage first. It is an absolute indication for lung isolation. If both lungs are lavaged during the same procedure, it significantly impairs effective oxygenation.

             Lung isolation for unilateral bronchoalveolar lavage is obtained by a double-lumen tube under general anesthesia. Proper positioning of the tube by bronchoscopy is essential prior to the lavage to prevent contamination of the opposite lung. A water-tight seal with the cuffs is also essential prior to the lavage. The procedure is normally done in the supine position; lavaging a dependent lung in a lateral position helps to minimize soiling of the nondependent lung, but the ventilation–perfusion mismatch caused by ventilating a nondependent lung which is not perfused is severe and makes this clinically impossible. Warm normal saline is infused into the lung to be treated and is drained by gravity; treatment continues until the fluid returning is clear (about 10–20 L). Patient can be extubated after carefully suctioning out both the lungs or the double-lumen tube is replaced by a single-lumen tube at the end of the procedure.

  36.   B.    Right-ventricular failure caused by increase in right-sided afterload (increased pulmonary artery resistance) may recover after isolated lung transplantation, and they do not require combined heart–lung transplantation. Such is not the case in patients with Eisenmenger syndrome who require combined heart–lung transplantation. However, normal left-ventricular function and absence of significant coronary artery disease or other serious health problems is ensured before lung transplantation, as the wait list of patients for the organs are long. Respiratory failure caused by cystic fibrosis, bullous emphysema, or vascular diseases are usually bilateral and necessitate a double-lung transplant. It can be done using cardiopulmonary bypass or sequentially using one-lung ventilation depending on the pulmonary artery pressures and the ventricular function. Single-lung transplantation is being increasingly performed for patients with chronic obstructive pulmonary disease. Organ selection is based on size, ABO compatibility, and cytomegalovirus serology matching.

  37.   A.    A newly transplanted lung lacks the neural innervation, lymphatic drainage, and bronchial circulation, which were present in the explanted lung. Central respiratory pattern generated by centers in the brain stem is unaffected. Hypoxic pulmonary vasoconstriction, mediated locally is also unaffected. However, loss of lymphatic drainage increases extravascular lung water and predisposes the transplanted lung to pulmonary edema. Fluid restriction is fairly common after lung transplantation to prevent this from happening. Although some patients develop bronchial hyperreactivity, cough reflex is abolished below the carina. These patients usually get postoperative bronchoscopy to assess bronchial suture line, as they are prone for ischemic breakdown in the absence of bronchial circulation.

  38.   C.    Anesthetic considerations in patients with esophageal disease include the risk of pulmonary aspiration, use of a DLT, invasive monitoring, intravenous access sufficient for rapid fluid resuscitation, maintaining normothermia, and use of transcutaneous pads for defibrillation if needed. The esophageal disease process predisposes them to aspiration due to obstruction, altered motility, or abnormal sphincter function. The risk of aspiration continues into the postoperative period. Even though a DLT (Double lumen tube) facilitates surgical exposure, it is not always required. Invasive monitoring with arterial line and central venous pressure monitoring help guide hemodynamic management. However, a PAC (Pulmonary artery catheter) is used only for patients with significant cardiac disease. Substernal and diaphragmatic retractors used during the transhiatal approach to esophagectomy can interfere with cardiac function. Surgeons hand can interfere with cardiac filling while bluntly dissecting the esophagus from the posterior mediastinum. Since the vagus runs very close to the esophagus, marked vagal stimulation can result in profound bradycardia or even cardiac arrest—transcutaneous pads helps in these situations. Hypothermia increases coagulopathy and increases cardiac arrhythmias and should be avoided. The potential for rapid massive blood loss is significant as the surgery is near the major blood vessels.

  39.   B.    There has been a recent resurgence in LVRS, even though NETT, a trial of usual medical therapy versus usual medical therapy plus LVRS, suggested lack of efficacy of LVRS. Anesthetic considerations for LVRS include watching out for pneumothorax caused by a ruptured bleb, use of double-lumen tubes to allow selective ventilation and to facilitate surgery, using a lower FIO2 to a goal SpO2 of 90%, limiting the degree of positive-pressure ventilation (<30 cm H2O peak inspiratory pressure), prolonging the expiratory time, and early extubation. Total IV anesthesia techniques using propofol and remifentanil or inhalational agents like desflurane with short-acting neuromuscular blocking agents help facilitate early extubation. If the patient cannot be extubated at the conclusion of the procedure, the double-lumen tube is exchanged for a single-lumen tube to decrease airway resistance.

  40.   B.    Equal pressure point refers to the point in the airway where intraluminal pressure and extraluminal pressure (pleural) are the same. This is normally beyond the 11th to 13th generation of bronchioles where cartilaginous support is absent. This is the point where dynamic airway compression can occur—this refers to the phenomenon in which collapsible membranous portion of the airway gets compressed by the extraluminal pressure generated by a forced expiration. It is facilitated by the large pressure drop across the airways causing a higher gradient between extra and intraluminal pressures. Obstructive airway diseases predispose the patients to dynamic airway compression. Elastase deficiency in emphysema causes decreased elastic support in smaller airways. The bronchoconstriction and inflammation of asthma predisposes to reversal of transmural gradients. Such patients usually adapt by pursed-lip breathing and terminating the expiration early before functional residual capacity falls below closing capacity (auto PEEP). However, the increase in lung volume and slowing of expiration caused by such a maneuver helps to stent the airway open. The increase in lung volume increases the intraluminal pressure and dilates the airways, and the slow expiration reduces the decrease in pressure from the alveoli to the mouth because lower driving pressures are sufficient for lesser flows. This shifts the equal pressure point to the noncollapsible larger airways or to the mouth.

  41.   C.    Any lesion causing a compression of the superior vena cava (SVC) and impedes blood return from head and neck can cause venous engorgement and edema of the head, neck, and arms. This is usually produced by a mediastinal tumor causing compression of the mediastinal structures including the SVC. It can also be caused by an occlusive thrombus in the SVC. Among the mediastinal neoplasms, lymphomas are the most common causes for SVC syndrome. But other mediastinal tumors like germ-cell tumors or pulmonary lesions with secondary lymphadenopathy may also be responsible. These cases are very difficult as induction of anesthesia in a supine position causes severe airway obstruction and cardiovascular collapse. The airway obstruction is due to direct mechanical compression as well as mucosal edema. Attempts should be made to decrease the size of the mass and the degree of mediastinal compression should be made prior to elective surgery. This includes radiation therapy, chemotherapy, and steroids. An empiric treatment with steroids may be attempted prior to a tissue diagnosis in this 12-year old. A preoperative echocardiogram can quantify the degree of compromise in cardiac function, presence of a thrombus, or dynamic inflow obstruction in the presence of pericardial fluid. A CT scan/MRI will help diagnose the presence of tracheomalacia/erosion and the level of the lesion. If induction of general anesthesia is required in the presence of SVC syndrome, awake fiberoptic intubation is the preferred method and inhalational anesthetics can be used to attain a deep plane of anesthesia in a spontaneously breathing patient after intubation. A rigid bronchoscope and ability to go on cardiopulmonary bypass are other precautionary measures that can be taken. <CT>