HYPERINFLATION THERAPY

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CHAPTER 7 HYPERINFLATION THERAPY

PRETEST QUESTIONS

Answer the pretest questions before studying the chapter. This will help you determine your strong and weak areas in the material covered.

1. Which of the following increases the delivered VT to a patient taking an IPPB treatment with the Bird Mark 7 IPPB machine?

1. Increasing flow rate
2. Increasing inspiratory pressure
3. Decreasing sensitivity
4. Decreasing flow rate
A. 1 and 2 only
B. 1 and 3 only
C. 2 and 4 only
D. 1, 2, and 3 only

2. During an IPPB treatment, the patient suddenly complains of chest pain and becomes short of breath. On assessing the patient, you auscultate the chest and hear decreased breath sounds on the left. These findings are consistent with which of the following?

A. Atelectasis
B. Left-sided pneumothorax
C. Pulmonary embolism
D. Pleural effusion

3. The respiratory therapist is administering IPPB, and the patient complains of feeling light-headed and dizzy. What should the therapist do to correct this?

A. Instruct the patient to pause longer between breaths.
B. Instruct the patient to take deeper breaths.
C. Increase the inspiratory pressure.
D. Decrease the inspiratory flow.

4. While the respiratory therapist is administering IPPB, the patient begins coughing up large amounts of blood. The therapist should

A. Continue the treatment and notify the physician that a chest radiograph is needed.
B. Decrease the inspiratory pressure.
C. Stop the treatment briefly and resume it when the patient is feeling better.
D. Stop the treatment and notify the physician.

5. Which of the following are hazards of IPPB therapy?

1. Excessive ventilation
2. Increased cardiac output
3. Decreased ICP
A. 1 only
B. 2 only
C. 1 and 3 only
D. 2 and 3 only

6. The respiratory therapist has received an order to deliver IPPB to a patient with head trauma. What modifications in therapy may benefit this patient?

1. Use a higher flow rate.
2. Use lower peak pressures.
3. Set the sensitivity to −5 cm H2O.
A. 1 only
B. 2 only
C. 1 and 2 only
D. 2 and 3 only

7. Incentive spirometry is ordered for a patient after abdominal surgery. Which of the following statements by the respiratory care practitioner would be most appropriate in the initial explanation of the therapy to the patient?

A. “You may experience pain and light-headedness from this therapy.”
B. “We are trying to improve your inspiratory capacity.”
C. “This therapy will help you take deep breaths and expand your lungs.”
D. “Your doctor has ordered this therapy to prevent atelectasis.”

8. Sustained maximal inspiratory maneuvers performed with an incentive spirometer would be MOST effective in the

A. Treatment of pneumonia.
B. Prevention of pneumonia.
C. Treatment of preexisting atelectasis.
D. Prevention of atelectasis.

9. The initial inspiratory goal for a patient receiving incentive spirometry should be

A. Twice the patient’s measured tidal volume.
B. Equal to the patient’s measured tidal volume.
C. At least 1500 mL.
D. 5 mL/kg of body weight.

See answers and rationales at the back of the text.

REVIEW

I. INTRODUCTION TO IPPB THERAPY

CRT Exam Content Matrix: IIA6a, IIA11b, IIB5, IIIA1a-b, IIID2a, IIIF1, IIIF2a

RRT Exam Content Matrix: IIA2a, IIIA1a-b, IIID2a, IIIF1, IIIF2a

A. IPPB is defined as a short-term (10 to 15 min) breathing treatment in which pressures above atmospheric pressure are delivered to the patient’s lungs via a pressure-limited ventilator.
B. Effective IPPB depends on four factors
1. A respiratory therapist who has been well trained and has a knowledge of the equipment, medications used, reasons for therapy, and side effects and goals of therapy
2. A relaxed, informed, and cooperative patient
3. A pressure-limited IPPB machine with a means of measuring VT
4. Proper instruction of the patient on breathing patterns and cough techniques by the respiratory therapist

II. PHYSIOLOGIC EFFECTS OF IPPB

A. Increased Mean Airway Pressure
1. During normal spontaneous inspiration, airway pressure drops below atmospheric pressure (−2 cm H2O), thereby setting up a pressure gradient between the atmosphere (at nose and mouth) and the airways. Air flows into the airways, gradually building pressure back up to atmospheric level. Air flow stops, and passive exhalation occurs as a result of the natural recoil properties of lung tissue. The lung is never subjected to significant positive pressure.
2. During an IPPB machine breath, positive pressure is applied to the airways to improve the ventilation status of the lung. This is what is meant by “increased mean airway pressure”; it is the average (mean) pressure in the airways during one breathing cycle.
B. Increased VT
1. IPPB should deliver a VT of 12 to 15 mL/kg of ideal body weight.
2. Delivered VT depends on the patient’s lung status (e.g., compliance and airway resistance).
a. Decreased compliance results in a decreased delivered VT.
b. Increased compliance results in an increased delivered VT.
c. Decreased airway resistance results in an increased delivered VT.
d. Increased airway resistance results in a decreased delivered VT.
3. Delivered VT may be measured with a respirometer or gas-collection bag on the exhalation port.
4. The inspiratory pressure control adjusts the delivered VT.
a. Increase pressure to increase delivered VT.
b. Decrease pressure to decrease delivered VT.
C. Decreased Work of Breathing
1. A patient experiencing acute hypoventilation may avoid intubation and use of a mechanical ventilator (possibly only temporarily) by administration of frequent IPPB treatments.
2. The practitioner must encourage the patient to relax and allow the IPPB unit to do all the work for the patient’s work of breathing to decrease.
3. IPPB may increase the patient’s work of breathing if
a. The machine sensitivity (triggering mechanism) is set too low, making it difficult for the patient to cycle the machine into inspiration. The patient should be required to pull no more than −2 cm H2O of pressure to initiate inspiration.
b. The flow rate is inadequate to meet the patient’s inspiratory flow demands. Increase the flow rate if inspiratory time is prolonged and if the manometer needle is rising slowly or lagging to peak pressure. Another indication that the flow is inadequate is if the manometer needle remains near zero throughout most of the inspiration and then rises quickly to peak pressure.
c. The delivered VT is inadequate. Monitor the VT and listen to basilar breath sounds to ensure adequate volumes are being delivered.
d. Adequate time is not allowed for passive exhalation to occur. The machine sensitivity (triggering mechanism) may be set too high, which may result in self-cycling.

D. Alteration of the Inspiratory and Expiratory Time
1. When a patient with respiratory difficulties receives IPPB, the alveolar ventilation should be improved, thereby making the patient more comfortable, less “air hungry,” and returning the inspiration:expiration (I:E) ratio and respiratory rate to normal.
2. The normal I:E ratio for an adult is 1 : 2.
E. Mechanical Bronchodilation
1. A patient with respiratory disease experiences an increased resistance to air flow as the diameter of the airways decreases as a result of bronchospasm, secretions, and other factors.
2. When positive pressure is applied to constricted airways, dilation of these airways can occur to a greater degree than with spontaneous breathing.

image Some studies show that higher flow rates and pressures may cause a bronchoconstrictive reflex in the airways. This may be counteracted by administering bronchodilating agents.

F. Cerebral Blood Flow Alteration
1. A patient receiving IPPB may experience light-headedness, dizziness, or faintness from reduced PaCO2 levels and the resultant alkalemia. Decreased PaCO2 levels result in cerebral vasoconstriction, thus decreasing cerebral blood flow.
2. To prevent reduced PaCO2 levels, encourage the patient to breathe slowly and to pause between breaths.
3. A 50-mL flex tube should be connected between the mouthpiece and manifold, allowing a slight rebreathing of CO2 and preventing decreased PaCO2 levels.

III. INDICATIONS FOR IPPB THERAPY

A. Increased work of breathing
B. Hypoventilation
C. Need for delivery of medications to a patient who cannot take a deep breath (10 to 15 mL/kg of ideal body weight)
D. Inadequate cough
E. Increased airway resistance
F. Atelectasis, especially in sedated postoperative patients and patients recovering from chest or abdominal surgery who are reluctant to breathe deeply
G. Pulmonary edema
H. Need for aid in weaning from continuous mechanical ventilation

IV. HAZARDS OF IPPB THERAPY

A. Excessive Ventilation
1. Leads to decreased PaCO2 levels, causing cerebral vasoconstriction and resulting in dizziness
2. Patient should be instructed not to stand or walk immediately after the treatment.
B. Excessive Oxygenation
1. Patients with severe COPD may breathe by the “hypoxic drive” mechanism. If the IPPB treatment is given with O2, it may elevate the PaO2 above the normal level (50 to 65 mm Hg), which may knock out the patient’s drive to breathe.

image Exam Note

Although the “hypoxic drive” theory is highly debated and its validity is often questioned, the exam may still ask questions dealing with this subject.

2. Hypoxic drive potential is indicated by the following ABG levels: pH, 7.35 to 7.40 (compensated); PaCO2, more than 50 mm Hg; PaO2, less than 65 mm Hg.
C. Decreased Cardiac Output
1. Positive pressure applied to the airways is likewise exerted on blood vessels returning blood to the heart. This restricts venous blood return to the heart, which in turn decreases cardiac output from the left ventricle.
2. Avoiding high inspiratory pressures and long inspiratory times minimizes this hazard.
3. If there is a decreased venous return during the therapy, the patient may experience tachycardia and a decrease in systemic blood pressure, which is caused by decreased left ventricular filling pressure.
D. Increased ICP
1. Blood flow from the head is restricted as positive pressure is exerted on the superior vena cava, which is returning blood to the heart from the upper body. This keeps more blood in the cerebral vessels, which elevates ICP levels.
2. Normal ICP is less than 10 mm Hg.
3. Using lower pressures and shorter inspiratory times (increased flows) and having the patient positioned in the Fowler position or sitting on the edge of the bed minimizes this hazard.
4. This is not a common hazard, except in patients with closed head injuries or CNS disease.
E. Pneumothorax
1. Most common in patients with COPD with bullous disease or emphysema with bleb formation.
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