Chapter 16: Noninvasive Mechanical Ventilation of the Child Test Bank

Multiple Choice

1. What are the primary objectives of noninvasive positive-pressure ventilation (NPPV)?

I. To increase the likelihood of successful weaning from mechanical ventilation

II. To improve respiratory gas exchange

III. To decrease the patient’s work of breathing

IV. To reduce the risk of ventilator-associated pneumoniaa. I and IV only b. II and III only c. I, II, and III only d. II, III, and IV only

ANS: B

The primary objectives of NPPV in children with acute respiratory distress are to decrease the work of breathing and improve respiratory gas exchange. These objectives are outlined in Box 16-2 in the textbook.

REF: p. 288

2. What effect should the therapist expect to observe after successful initiation of continuous positive airway pressure (CPAP) on a neonate who has a restrictive lung disorder? a.

Decreased arterial partial pressure of carbon dioxide (PaCO2) b. A lower mean airway pressure c. A normal alveolar–arterial oxygen tension difference [P(A–a)O2] gradient d. Increased lung volume

ANS: D

An appropriate level of CPAP must increase end-expiratory lung volume (functional residual capacity) and thereby improve oxygenation. CPAP therapy may or may not improve tidal volume and alveolar ventilation. In children and neonates with restrictive respiratory dysfunction and decreased lung compliance, CPAP therapy can raise tidal volume.

REF: p. 289

3. Which of the following restrictive disorders are likely to respond to both NPPV and CPAP in children?

I. Atelectasis

II. ARDS

III. PneumoniaIV. Morbid obesity a. I, II, and III only b. II and IV only c. I, III, and IV only d. II, III, and IV only

ANS: C

Children with restrictive lung disorders (including atelectasis, pneumonia, and neuromuscular weakness) and morbid obesity typically present with hypoxemia and a reduction in functional residual capacity. Both NPPV and CPAP are effective in this setting to restore end-expiratory volume.

REF: p. 289

4. A child with a chronic disorder complicated by alveolar hypoventilation is placed on intermittent NPPV at night. What is the primary goal of this therapy? a. To decrease the work of breathing b. To decrease the need for inserting an endotracheal tube c. To improve the quality of sleep and reduce daytime symptoms d. To improve arterial oxygenation

ANS: C

NPPV is offered to patients with chronic hypoventilation disorders as a clinical benefit used at night to reduce the severity of daytime symptoms associated with chronic hypercarbia headache and fatigue.

REF: p. 289 a. 3 cm H2O b. 2 cm H2O c. 1 cm H2O d. 1.5 cm H2O

5. HFNC has been ordered for a newborn at a rate of 3 L/min. What is the approximate nasopharyngeal pressure at this setting?

ANS: D

In a study of infants with bronchiolitis, nasopharyngeal pressures increased linearly (0.45 cm H2O for each 1 L/min increase) with HFNC rates up to 6 L/min.

REF: p. 289 a. Treatment of hypoxemic exacerbation of children with chronic neuromuscular disorders b. Treatment of hypercapnic exacerbation of children with chronic neuromuscular disorders c. Treatment of exacerbation of children with acute asthma attacks d. Treatment of exacerbation of children with pulmonary edema due to congenital heart defects

6. What is considered the most successful therapeutic condition where NPPV can be used in children?

ANS: B

Perhaps the most successful experience with NPPV as a rescue therapy is its use in acute exacerbations of hypercarbic respiratory failure in children with chronic neuromuscular disorders.

REF: p. 291 a. As a bridge to transplantation b. As the routine treatment for bronchopulmonary hygiene c. As the primary indication for reduction of exacerbations d. As the primary treatment of hypoventilation

7. In what particular setting has long-term use of NPPV on children with cystic fibrosis been successful?

ANS: A

In children with advanced cystic fibrosis lung disease, long-term NPPV has been successful as a bridge to lung transplantation.

REF: p. 291 a. For every patient who is hypoxemic b. When OSA is complicated by alveolar hypoventilation and hypercarbia c. When OSA is complicated by hypoxemia d. For every patient who is hypoxemic and hypercapnic

8. When should NPPV be selected over CPAP in children with OSA?

ANS: B

Although there are no clear guidelines, selection of NPPV over CPAP in children with OSA is typically made in OSAs complicated by alveolar hypoventilation and hypercarbia.

REF: p. 292 a. The therapist should increase the pressure limit. b. The therapist should increase the inspiratory flow. c. The therapist should increase the length of the inspiratory time. d. The therapist should verify that the ventilator automatically compensates for this leak.

9. A patient receiving bilevel ventilation develops a small leak at the interface. What action should the therapist take at this time?

ANS: D

Most bilevel ventilators available for commercial use are adept at delivering sufficient flow to reach the targeted level of inspiratory pressure. These devices also have a flow compensation feature that ensures that small leaks around the interface or through the mouth do not seriously impair performance. However, the capacity of NPPV devices to compensate for severe leaks is limited, and the result is greater patient/ventilation asynchrony, cited as a common reason for NPPV failure in the acute setting.

REF: p. 292

10. A patient receiving PAV is noticed to increase breathing effort. Which parameters will the ventilator modify to respond to this patient’s increased respiratory demand?

I. Increase flow

II. Increase tidal volume

III. Increase pressureIV. Increase CPAP a. I and II only b. II, III, and IV only c. III, IV, and V only d. I and III only

ANS: D

Unlike PSV, which uses a preset inspiratory pressure, PAV provides inspiratory flow and pressure in proportion to the patient’s spontaneous breathing effort as determined by instantaneous feedback from an in-line pneumotachometer.

REF: p. 292 a. The preset VT should be equal to the patient’s estimated anatomic dead space volume. b. The delivered VT should be equal to the estimated anatomic dead space divided by the patient’s respiratory rate. c. The VT should be set by dividing the patient’s PaCO2 by two. d. The delivered VT should be set at twice the child’s physiologic VT

11. How should a volume-regulated ventilator for NPPV be adjusted to deliver the appropriate tidal volume (VT) to a pediatric patient?

ANS: D

To appropriately adjust a volume-controlled ventilator for NPPV, the delivered tidal volume should be approximately twice that of the child’s physiologic tidal volume to accommodate the dead space of the nasopharynx and conducting airways.

REF: p. 293

12. When considering NPAV devices, what is considered the most beneficial effect over NPPV? a. Its effect on CO2 clearance b. Its faster restoration of oxygenation c. Its effect on cardiac filling pressures and volumes d. Its effect on spontaneous tidal volume

ANS: C

The advantage of these devices is a beneficial effect on cardiac filling pressures and volumes, a benefit found even in healthy individuals.

REF: p. 293

13. When a bilevel ventilator is used in the spontaneous/timed mode, at what point does the ventilator employ the timed feature? a. During exhalation b. To terminate inspiration c. Throughout the ventilatory cycle d. Only in the event of prolonged apnea

ANS: D

Most bilevel pressure-targeted ventilators suitable for NPPV feature CPAP, spontaneous, timed, and spontaneous/timed operating modes. In the spontaneous/timed mode, the flowtrigger feature is activated. The ventilator responds to a threshold level of inspiratory flow or to a change in volume that is initiated by the patient’s spontaneous respiratory effort. At the inspiratory flow threshold, the ventilator delivers additional gas flow to reach the preset inspiratory positive airway pressure (IPAP). Exhalation occurs after the inspiratory flow peaks and then decreases to a threshold level. The ventilator triggers in the timed mode only in the event of prolonged apnea.

REF: p. 293 a. Timed b. Spontaneous c. CPAP d. Spontaneous/timed

14. When NPPV is used to ventilate pediatric patients, which operating mode of ventilation is generally used?

ANS: D

Most bilevel pressure-targeted ventilators suitable for NPPV feature CPAP, spontaneous, timed, and spontaneous/timed (assist-control) operating modes. Pediatric patients are typically managed in the spontaneous/timed mode. The chief advantage of this mode is patient comfort. The child’s inspiratory efforts are assisted with the inspiratory pressure support feature, which responds favorably to the patient’s inspiratory efforts.

REF: p. 293 a. Optimize inspiratory flow. b. Titrate inspiratory pressure to achieve a tidal volume of 5 mL/kg. c. Set the device on spontaneous-timed mode. d. Minimize leaks around the interface.

15. What is the most effective way for the therapist to promote effective triggering and prevent asynchrony with NPPV?

ANS: D

The best way for the practicing therapist to promote effective triggering and prevent asynchrony with NPPV is to minimize leaks around the mask interface. In the presence of a significant leak, the inspiratory pressure target is never reached, resulting in a long inflation time as the unit delivers massive amounts of inspiratory flow in an attempt to attain the preset inspiratory pressure.

REF: p. 294 a. It represents the mean airway pressure to which the patient’s lungs are exposed. b. It determines the patient’s tidal volume. c. The IPAP–EPAP gradient determines the inspiratory time. d. This gradient determines the level of pressure support the patient will receive.

16. What is the clinical significance of the IPAP–EPAP gradient in bilevel NPPV?

ANS: B

The IPAP should be set above the expiratory positive airway pressure (EPAP) to raise the child’s tidal volume, “unload” the respiratory muscles, and decrease respiratory distress. The differential between the IPAP and EPAP adjustment determines the tidal volume.

REF: p. 294 a. 20 to 25 cm H2O b. 15 to 20 cm H2O c. 8 to 12 cm H2O d. 5 to 10 cm H2O

17. What level of IPAP is typically sufficient to achieve the goals of NPPV in pediatric patients?

ANS: C

In day-to-day clinical practice, an IPAP setting between 8 and 12 cm H2O is typically sufficient to achieve the goals of NPPV in pediatric patients.

REF: p. 294 a. IPAP b. Mode c. Respiratory rate d. EPAP

18. Which of the following bilevel ventilator settings influences upper airway stability?

ANS: D

The EPAP adjustment with NPPV primarily determines the end-expiratory lung volume and maintains the stability of the upper airway. In a typical pediatric application of NPPV, EPAP levels of 6 to 8 cm H2O are effective in improving oxygenation and preventing obstructive apnea. Most children, regardless of the setting or indication, poorly tolerate EPAP levels above 10 cm H2O.

REF: p. 294

19. Which of the following NPPV interfaces should the therapist consider when a child complains of discomfort with a nasal mask?

I. Oronasal mask

II. Nasal plugs

III. HelmetIV. Nasal pillows a. I and II only b. I and III only c. II and IV only d. III and IV only

ANS: C

Nasal plugs or pillows can be substituted for nasal masks in children who complain of discomfort with the nasal mask. Nasal plugs or pillows are not used as often because most children eventually adapt to the nasal mask very well. They may have some role in teenagers because they place no pressure on the face and do not interfere with vision.

REF: p. 295 a. Ventilator-associated pneumonia b. Gastric insufflation c. Claustrophobia d. Skin irritation caused by the interface

20. What is the most common complication associated with NPPV among pediatric patients?

ANS: D

The most common minor complication reported is skin irritation due to the nasal mask (48%), leading to skin necrosis in up to 8%.

REF: p. 296 a. Cardiovascular instability b. Nasopharyngeal obstruction c. Inability to handle oral secretions d. Extreme agitation or anxiety

21. What is the only absolute contraindication to a trial of NPPV in pediatric patients with acute respiratory distress?

ANS: A

The only absolute contraindication to a trial of NPPV in pediatric patients with acute respiratory distress is cardiovascular instability. Relative contraindications include nasopharyngeal obstruction, inability to handle oral secretions, and extreme agitation or anxiety.

REF: p. 296

Chapter 17: Mechanical Ventilation of the Neonate and Pediatric Patient Test Bank

Multiple Choice

1. What frequency defines high-frequency modes of ventilation?

a. > 40 breaths per minute b. > 100 breaths per minute c. > 150 breaths per minute d. > 200 breaths per minute

ANS: C

Low-frequency ventilation (LFV) is identified as ventilation modes that provide breaths per minutes of < 150; high-frequency ventilation (HFV) as modes of ventilation that provide breaths per minute of > 150.

REF: p. 301 a. Diffuse, heterogeneous lung disease b. Existing pulmonary air leak syndrome c. Severe bronchiolitis d. PaO2/FiO2 ratio of 300

2. Which of the following are indications for HFV?

ANS: B

The bulk of clinical data regarding appropriate application of HFV devices has been acquired from neonatal humans and animals. From these studies, two clear indications for HFV use during either routine or rescue circumstances have evolved. They include diffuse, homogeneous lung disease (or the atelectasis-prone lung), in which LFV management is failing or may lead to increased risk of pulmonary morbidity, and existing pulmonary air leak syndromes (e.g., pneumothorax and PIE).

REF: pp. 302-303 a. High-frequency jet ventilation (HFJV) b. High-frequency oscillatory ventilation (HFOV) c. High-frequency flow interruption (HFFI) d. Conventional ventilation (CV)

3. Which of the following forms of mechanical ventilation is the most efficacious method for acquired bronchopleural fistulas?

ANS: A

The ability to provide adequate ventilation with low mean and peak pressures in children with otherwise normal lungs offers a substantial advantage of HFJV over HFOV and LFV. Furthermore, this feature makes HFJV a more efficacious method of treating traumatic or acquired bronchopleural fistulas than other forms of respiratory support.

REF: p. 303 a. Pulmonary capillary perfusion b. Ventilation–perfusion relationships c. Pulmonary compliance d. Volume compressed in the ventilatory circuit at end inspiration

4. During volume-controlled ventilation, which of the following factors influences the peak inspiratory pressure?

ANS: C

A constant tidal volume and flow rate characterize volume ventilation, and the resulting peak inspiratory pressure varies with changes in respiratory system compliance and resistance. When a flow-controlling valve is used, tidal volume is calculated by measuring the flow delivered over a preset inflation time.

REF: p. 306

5. Which of the following modes of ventilation attempts to maintain a minimum target tidal volume with a constant pressure by manipulating the inspiratory flow? a. Synchronized intermittent mandatory ventilation (SIMV) b. Pressure support ventilation (PSV) c. Volume-assured pressure support (VAPS) d. Pressure-regulated volume control (PRVC)

ANS: D

Pressure-regulated volume control (PRVC) attempts to maintain a minimum target tidal volume with a constant pressure by manipulating the flow waveform.

REF: p. 308

6. The therapist is about to mechanically ventilate a neonate with a ventilator that delivers the volume guarantee mode. Which of the ventilator settings does the therapist need to set for this mode?

I. Minute ventilation

II. Tidal volume

III. Inspiratory timeIV. Inspiratory flow a. I and II only b. II and IV only c. I, III, and IV only d. II, III, and IV only

ANS: D

Volume guarantee (VG) is another form of adaptive-control ventilation that is used in one type of neonatal ventilator. The operator sets a tidal volume, inspiratory time, and flow rate. This mode can also be applied to pressure support ventilation. The ventilator incorporates a proximal flow sensor at the patient airway. The microprocessor assesses an eight-breath historical average of expired tidal volume and will increase pressure on the basis of these measurements up to the pressure limit to deliver the target volume.

REF: p. 309

7. When airway pressure release ventilation is used, what physiologic process occurs as the higher pressure is released and the lower is achieved? a. Increased functional residual capacity b. Increased tidal volume c. Improved oxygenation d. Exhalation of carbon dioxide

ANS: D

The short intermittent decreases in the CPAP level allow alveolar emptying of gases. Unlike conventional CPAP, however, the intermittent release of pressure augments ventilation and allows elimination of carbon dioxide.

REF: p. 310 a. Inspiratory flow b. Plateau pressure c. Inspiratory time

8. Enhanced diffusion in HFV is a function of which of the following factors?

d. Respiratory frequency

ANS: D

The impact of enhanced diffusion, the product of tidal volume and rate, and the relationship between pulmonary units may all vary depending on the HFV technique used, the settings chosen, the patient's lung size, and pathologic conditions.

REF: p. 311 a. By increasing the continuous distending pressure b. By reducing the peak–trough pressure gradient c. By increasing the expiratory flow resistance d. By decreasing the mean airway pressure

9. How is the high-volume strategy achieved when the goal is to deliver a high lung volume to a neonate receiving HFV?

ANS: A

One method is to increase the distending pressures ( or CDP) in small increments (1 to 2 cm H2O) while watching for improvement in oxygenation (arterial blood gas determinations, transcutaneous carbon dioxide, or pulse oximetry saturations) and mean lung volumes (MLV) determined by chest radiograph. Mean airway pressure is increased until oxygenation improves significantly or until MLV reaches desired levels, or both, which may be determined by the presence of a well-inflated lung on a radiograph (see Figure 17-6 in the textbook). While using this method, care must be taken to anticipate silent lung recruitment and to reduce as appropriate to avoid serious impairment to venous return and reduction in cardiac output. Silent lung recruitment is gradual lung inflation taking place with static settings (see Figure 17-7 in the textbook). Clinical clues heralding this include rapid improvements with subsequent unexplained decrements in oxygenation, decreasing PaCO2 without changes in oscillatory amplitude (improving compliance), and, finally, clinical changes in perfusion. These problems often can be avoided with diligence and anticipation. Silent recruitment, although more common during initial HFV management, can occur any time attempts are made to optimize MLV. Data confirm the pulmonary, central nervous system, and cardiovascular safety and efficacy of this technique.

REF: pp. 313-314

10. What is a frequent requirement when employing the low-volume strategy while ventilating a neonatal patient with pulmonary interstitial emphysema by HFV? a. High inspiratory flow b. Positive end-expiratory pressure c. High inspired fraction of oxygen (FiO2) d. Longer inspiratory time

ANS: C

Low-volume strategy is accomplished with all HFV systems by using a lower than the process creating the problem. Patients for whom this strategy is used are usually undergoing CV before being switched to HFV. This allows the lung to derecruit and isolate damaged areas from inflation pressures. The consequence of this, however, is the frequent requirement for a higher FiO2. In addition, tidal volume delivery must be decreased to further reduce tidal volume exposure while using I/E ratios and ventilatory frequencies that maximize gas egress.

REF: pp. 315-316 a. Trigger dyssynchrony b. Excess tidal volume c. Air trapping d. Ventilator circuit leak

11. On the basis of the following flow/time scalar, which of the following conditions has developed?

ANS: C

Two disadvantages exist when manipulating frequency at higher rates or inverse I/E ratios. The first is that, as frequency increases, air trapping is likely to occur. Figure 17-9 in the textbook illustrates this in a flow/time scalar graphic. Notice that flow does not come back to baseline. The second is that, when the I/E ratio is kept constant, minute ventilation does not change.

REF: p. 317 b. It increases. c. It increases only if compliance changes. d. It decreases.

12. During high-frequency ventilation, as the diameter of the ETT increases, what happens to the delivered tidal volume under the same pressure settings? a. It does not change.

ANS: B

As ETT dimensions and compliance decrease, so does tidal volume output from the HFV tested. This occurs in the presence of stable ventilator settings. Therefore any clinical change causing a decrease in ETT diameter, such as reintubation with a different-sized ETT or partial ETT obstruction with tracheal secretions, alters the delivered tidal volume in a direct proportion. Furthermore, improvements in lung compliance (e.g., volume recruitment) and decrements in lung compliance (e.g., patent ductus arteriosus or alveolar derecruitment) have a direct effect on tidal volume.

REF: p. 318

13. Which of the following adjustments should the therapist consider to improve ventilation on a patient undergoing HFV? a. Increase frequency b. Increase c. Increase inspiratory time d. Decrease frequency

ANS: D

Changes in ventilator rate at a given pressure amplitude cause an inverse change in tidal volume. Thus, when ventilation must be improved, a reduction in breathing frequency improves ventilation because the increased volume output per stroke has a greater impact on ventilation than does the decrease in stroke frequency. The converse is also true. When less ventilation is needed and pressure amplitude is already minimized, increasing breathing frequency will further decrease tidal volume and allow weaning from ventilation.

REF: p. 318 a. Frequency b. Oscillatory amplitude c. Peak inspiratory pressure d. IPAP (inspiratory positive airway pressure) and EPAP (expiratory positive airway pressure)

14. During HFOV, which of the following factors has a direct influence on a neonate’s delivered tidal volume?

ANS: C

During HFOV, peak and trough pressures are measured, although they are not usually displayed. Because of the impact of the ETT on transmitted pressure, these values have only relative significance. Of more importance is the difference between peak and trough pressures, known as oscillatory amplitude or simply the delta P. Delivered volume is directly proportional to this peak–trough difference, and adjustments result in changes in tidal volume.

REF: p. 319 a. Gas flow through the pneumotachometer during expiration b. Peak inspiratory pressure-trough pressure gradient c. Inspiratory valve aperture d. Bias flow

15. During HFOV manipulation of which of the following components establishes the continuous distending pressure?

ANS: D

During HFV, especially HFOV, this pressure is directly controlled by the combination of bias flow and expiratory valve aperture.

REF: p. 323 a. Ventilation time constant b. Water level in the humidifier c. Location of the exhalation valve d. Size (inner diameter) of the endotracheal tube

16. Which of the following factors influences the gas volume compressed in the ventilator circuit?

ANS: B

The humidifier also represents a source for gas compression and is included in calculating compressible volume. Using a constant-level, self-feeding humidifier is necessary to minimize variations in compressible volume in all pediatric ventilation situations.

REF: p. 324

17. While checking the ventilator of a pediatric patient, the therapist observes the following volume–time scalar: a. Increase the sensitivity setting. b. Increase the tidal volume and increase the pressure setting. c. Increase both the inspiratory flow and the pressure setting. d. Check the patient–ventilator system for the presence of auto-PEEP.

What action should the therapist take at this time?

ANS: C

In general, air leaks are monitored by the difference between the tidal volume delivered by the ventilator and the patient's exhaled tidal volume. Another way to identify an air leak is via flow graphics. Figure 17-19 in the textbook illustrates an air leak on a volume–time scale. In most clinical situations, an air leak greater than 15% of the delivered tidal volume makes volume ventilation difficult.

REF: p. 324

18. Which of the following factors need to be considered for HFV ventilator circuits?

I. Time for gas egress during exhalation

II. Circuit compliance

III. Endotracheal tube sizeIV. Intrinsic timing mechanisms b. I, II, and III only c. I, II, and IV only a. I and II only

d. II, III, and IV only

ANS: C

With the exception of HFCV, all HFV devices have special patient circuit considerations. Each of them must (1) use very low circuit compliance to reduce compressible volume and increase the precision of control over the small volumes delivered; (2) have intrinsic timing mechanisms to allow breathing frequencies between 4 and 28 Hz (varies by device); (3) provide control over inspiratory times and circuit design to allow sufficient time for gas egress during exhalation; (4) adequately humidify gases; and (5) include alarms and fail-safe devices for patient safety.

REF: p. 325 a. 20% b. 25% c. 33% d. 50%

19. What is the recommended inspiratory time percent setting for HFOV?

ANS: C

The recommendation is a 33% inspiratory time for the HFOV devices approved in the United States. The result is that, for each completed respiratory cycle, one third is inspiratory and two thirds is expiratory. This relationship between the inspiratory and expiratory times enhances the egress of gas during exhalation because the 1:2 I/E ratio favors the expiratory phase, thereby reducing inadvertent air trapping or breath stacking.

REF: p. 323 a. Insufficient flow caused by insufficient driving pressure b. Pressure sensitivity set inappropriately low c. Excessive tidal volume d. Increased mechanical dead space

20. The following pressure–volume loop was obtained from a patient receiving mechanical ventilation in the pressure support mode. What type of problem does this ventilator graphic represent?

ANS: A

Ensuring that the initial inspiratory flow rate meets the patient's inspiratory demand is usually the best method of avoidance. An example of a pressure–volume loop demonstrating insufficient flow caused by insufficient driving pressure during PSV is shown in Figure 17-20 in the textbook.

REF: p. 328 a. Check the inflation pressure on the endotracheal tube cuff. b. Increase the pressure limit. c. Increase the delivered tidal volume. d. Increase the inspiratory flow.

21. On the basis of the following pressure–volume loop, what ventilator setting change should the therapist make?

ANS: D

An example of a pressure–volume loop demonstrating insufficient flow caused by insufficient driving pressure during PSV is shown in Figure 17-20 in the textbook.

REF: p. 328 a. Abrupt disconnection from mechanical ventilation b. Damped waveform caused by severe airflow obstruction c. Reduced pulmonary blood flow caused by overdistention of the lungs d. Secretions partially obstructing the sample line leading to the capnometer

22. Over the last 90 minutes, the therapist has obtained three arterial blood samples from an arterial line inserted in a neonate receiving mechanical ventilation and being monitored by capnometry. The PaCO2 values were as follows: (1) 47 mm Hg, (2) 46 mm Hg, and (3) 47 mm Hg. How should the therapist evaluate the following capnogram?

ANS: C

Falling partial pressure of end-tidal carbon dioxide (PETCO2), possibly from an increase in tidal volume or, if PaCO2 is unchanged, a reduction in pulmonary blood flow from overdistention or low cardiac output.

REF: p. 330

23. The therapist is conducting a ventilator check for a neonate and makes the following notations on the ventilator flow sheet:

•PEEP: 5 cm H2O

•Peak inspiratory pressure (PIP): 25 cm H2O

•Mandatory rate: 15 breaths/minute

•FiO2: 0.35 a. Shunt study b. Weaning from mechanical ventilation c. Inhaled nitric oxide d. High-frequency ventilation

On the basis of these observations, what should the therapist recommend for this neonate?

ANS: B

It is difficult to define at exactly what point during mechanical ventilation the weaning process should begin; however, most would agree that ideally it is after significant resolution or reversal of the pathologic condition for which it was initiated. Before weaning begins, the patient's condition should be stable and the patient should be receiving adequate nourishment and be able to breathe spontaneously and maintain a clinically acceptable PaCO2. The ventilator should be on acceptable settings: usually PEEP less than 8 cm H2O; peak pressure less than 30 cm H2O; ventilator rate less than 20 breaths/minute for a neonate, 15 breaths/minute for an infant/toddler, and 10 breaths/minute for a child or adolescent; and FiO2 less than 0.4 to 0.5.

REF: p. 331 a. By decreasing peak pressure b. By reducing oscillatory amplitude c. By minimizing d. By shortening the inspiratory time

24. How is the minute ventilation decreased when a patient is being weaned from HFOV?

ANS: B

Minute ventilation can be weaned by reducing oscillatory amplitude during HFFI and HFOV and by decreasing peak pressure and on-time with HFJV.

REF: p. 333 a. Counting the number of anterior ribs above the diaphragm b. Counting the number of posterior ribs above the diaphragm c. Counting the number of posterior ribs below the clavicle d. Counting the number of anterior ribs below the clavicle

25. How is the radiographic assessment of neonatal lung volume performed?

ANS: B

Radiographic assessment of lung volume takes considerable practice. The novice is cautioned that, although, in general, lung volume can be assessed by counting the number of posterior ribs seen above the diaphragm, radiographs of neonates are usually anterior-to-posterior views and counting ribs requires the juxtaposition of an anterior structure (the diaphragm) against a posterior structure (the rib interfacing with the diaphragm). This method assesses a threedimensional object (the lung) with a two-dimensional picture (the radiograph) and is vulnerable to technician-selected focus angles. It is possible, then, to underestimate or overestimate inflation.

REF: p. 333

26. The therapist notices that gas exchange has dramatically improved in a neonate undergoing HFOV. However, weaning has not been implemented accordingly. What are the consequences of failing to quickly wean a neonatal patient from HFV? a. Pulmonary overdistention b. Pulmonary hypertension c. Alveolar derecruitment d. Decreased pulse rate

ANS: A

The consequences of failing to wean the patient quickly enough are significant pulmonary overdistention and impairment of cardiac output. In neonates this complication can increase the risk of intracranial hemorrhage because venous return from vessels draining the head is impeded and venous hypertension and vessel rupture can ensue. Conversely, rapid weaning of can result in alveolar derecruitment, requiring reinitiation of lung recruitment procedures.

REF: p. 333 a. Observe the patient’s chest wall for movement. b. Increase conventional ventilation. c. Increase mean airway pressure on the HFV. d. Reduce the oscillatory amplitude.

27. Which of the following actions should a therapist consider in a patient suspected of having an airway obstruction while receiving HFV?

ANS: A

High-frequency ventilators are dependent on patient airway caliber for adequate volume delivery. A change in airway diameter (e.g., by accumulation of secretions or by migration of the tip of the ETT against the tracheal wall) may significantly reduce delivered volumes. The first step should be a quick assessment of chest wall movement. If chest wall motion is substantially decreased, a brief use of manual ventilation while troubleshooting the airway and ventilator may dramatically improve the situation. Steps should be taken to correct any problems with the ETT lumen or position (e.g., suctioning, chest radiograph).

REF: pp. 333-334 b. Large increases in tidal volume delivery can occur. c. Gas trapping may develop. d. Intrapulmonary shunting becomes likely.

28. Why may HFOV be considered a suboptimal ventilation strategy for patients who have either fresh particulate meconium aspiration or bronchopulmonary dysplasia? a. Ventilation time constants will be decreased.

ANS: C

Because a relatively high MLV is necessary for HFOV, this technique is not optimal for use in normal lungs. Furthermore, in conditions in which airway resistance is increased, such as fresh particulate meconium aspiration, bronchopulmonary dysplasia, and reactive airway disease, HFOV may not be optimal. Because of the tremendous impedance to flow created by reductions in airway lumen with these disorders (thus increasing pulmonary time constants), decreases in delivered tidal volume or gas trapping, or both, cause derangement in gas exchange. In contrast, HFJV or HFPV, using larger tidal volumes and lower breathing frequencies, may be more efficacious in conditions in which airway time constants are pathologically prolonged.

REF: p. 334