14 Intermittent Positive-Pressure Breathing

Note 1: This book is written to cover every item listed as testable on the Entry Level Examination (ELE), Written Registry Examination (WRE), and Clinical Simulation Examination (CSE)

The listed code for each item is taken from the National Board for Respiratory Care’s (NBRC) Summary Content Outline for CRT (Certified Respiratory Therapist) and Written RRT (Registered Respiratory Therapist) Examinations (http://evolve.elsevier.com/Sills/resptherapist/). For example, if an item is testable on both the ELE and the WRE, it will simply be shown as: (Code: …). If an item is only testable on the ELE, it will be shown as: (ELE code: …). If an item is only testable on the WRE, it will be shown as: (WRE code: …).

Following each item’s code will be the difficulty level of the questions on that item on the ELE and WRE. (See the Introduction for a full explanation of the three question difficulty levels.) Recall [R] level questions typically expect the exam taker to recall factual information. Application [Ap] level questions are harder because the exam taker may have to apply factual information to a clinical situation. Analysis [An] level questions are the most challenging because the exam taker may have to use critical thinking to evaluate patient data to make a clinical decision.

Note 2: A review of the most recent Entry Level Examinations (ELE) has shown an average of 3 questions (out of 140), or 2% of the exam, that cover intermittent positive-pressure breathing (IPPB). A review of the most recent Written Registry Examinations (WRE) has shown an average of 2 questions (out of 100), or 2% of the exam, that cover IPPB. The Clinical Simulation Examination is comprehensive and may include everything that should be known by an advanced level respiratory therapist

MODULE A

Initiate and adjust intermittent positive-pressure breathing (IPPB) therapy to achieve adequate respiratory support (Code: IIID2a) [Difficulty: ELE: R, Ap; WRE: An]

1. Description

The Respiratory Care Committee of the American Thoracic Society published the following definition in its 1980 Guidelines for the Use of Intermittent Positive Pressure Breathing (IPPB): “‘IPPB treatments’ refers to the use of a pressure-limited respirator to deliver a gas with humidity and/or aerosol to a spontaneously breathing patient for periods of time that are generally no greater than 15 to 20 minutes each.”

A pressure-limited respirator may be powered by compressed gas or electricity. The patient’s tidal volume (V_T) should be greater than normal when enhanced by IPPB. This greater-than-normal V_T is caused by the use of positive pressure against the lungs. Pressure is also directed against the airways and, through contact with the airways and lungs, the entire chest. The patient’s exhalation is usually passive but can be slowed through modification of the exhalation valve.

Shapiro and associates (1991) list the following as the physiologic effects of IPPB:

d. Alteration of the inspiratory/expiratory ratio

Patients with high airway resistance or low lung compliance often change their breathing patterns to reduce the WOB (see Chapter 1). These new breathing patterns may lead to worsening of the patient’s condition. Alteration of normal ventilation and perfusion ratios in the lungs may worsen hypoxemia. Properly administered and coached IPPB can be used to adjust the inspiratory/expiratory (I:E) ratio to the benefit of the patient. The patient can be taught how to breathe in a more physiologically normal pattern.

2. Indications

The following indications and guidelines are listed in the American Association for Respiratory Care (AARC) Clinical Practice Guidelines (1991, 2003) on IPPB:

a. To treat atelectasis when other deep breathing methods are ineffective

Patients who are uncooperative, unconscious, or physically incapable of being coached in deep-breathing and coughing techniques or in performing incentive spirometry (IS) may be helped by IPPB. An inspiratory pause at the end of the IPPB breath helps to better distribute the gas to open areas of atelectasis. As has been discussed in Chapter 7, a patient would benefit from IPPB rather than IS if any of the following apply:

• Inspiratory capacity (IC) of less than 12 mL/kg

• Vital capacity (VC) of less than 15 mL/kg

• Postoperative IC less than 33% of the predicted value (predicted IC = 1/3 [i.e., 0.33] × 50 mL/kg of ideal body weight)

The AARC guidelines on IPPB list the following poor pulmonary function values as supporting the need for IPPB because the patient would have an ineffective cough:

• Vital capacity (VC) less than 70% of predicted or less than 10 mL/kg

• Forced expiratory volume in 1 second (FEV₁) less than 65% of predicted

• Maximum voluntary ventilation (MVV) less than 50% of predicted

Exam Hint 14-1 (ELE)

It is important to understand the indications of IPPB versus incentive spirometry (IS) in the treatment of a patient with atelectasis. In general, IPPB would be indicated in a patient who could not properly perform IS.

b. To more effectively deliver aerosolized medications

If the patient cannot coordinate his or her breathing pattern to make use of a metered dose inhaler or handheld nebulizer, IPPB may be used. Examples of when IPPB is preferable include any situation in which the patient is unconscious, uncooperative, or physically incapable. These patients are physically unable to make effective use of simpler methods of lung inflation (incentive spirometry) or to take an aerosolized medication (metered dose inhaler or handheld nebulizer). Examples of these types of patients include the elderly, the chronically debilitated, patients with neuromuscular diseases, and patients with kyphoscoliosis. It may also be used to provide temporary support to home care patients.

c. To enhance the patient’s cough effort and sputum clearance

The combination of aerosolized saline, with or without a bronchodilator or mucolytic, and deeper tidal volumes may help the patient to cough more productively. The practitioner must stop the treatment periodically to coach the patient’s cough effort.

The following additional indications were listed in the Guidelines for the Use of Intermittent Positive Pressure Breathing (IPPB) published by the Respiratory Care Committee of the American Thoracic Society (1980).

d. To treat impending ventilatory failure as seen by an increased arterial carbon dioxide partial pressure (PaCO₂)

It may be possible to delay or avoid intubation and mechanical ventilation in the deteriorating chronic obstructive pulmonary disease (COPD) patient. The patient is able to relax and reduce the work of breathing (WOB) during a passive IPPB treatment. It may be necessary to give IPPB for 5 to 10 minutes as often as every 30 minutes to 1 hour. The treatment should also be given with the intention of helping the patient’s cough and sputum clearance. (An alternative to frequent IPPB treatments is noninvasive positive-pressure ventilation. This is discussed in Chapter 15.)

e. To help manage the patient with acute pulmonary edema

IPPB can help in the management of this patient by temporarily increasing mean airway pressure. This reduces the venous return to the heart, which may reduce pulmonary edema. The IPPB procedure does not correct the underlying cardiac problem, which must be treated by other means.

f. To induce a sputum sample for culture and sensitivity or other diagnostic studies

Inducing a sputum sample by IPPB is indicated only if simpler methods have failed.

g. To deliver medications for special purposes when simpler methods are ineffective

IPPB should be used to deliver medication when simpler methods fail, for example, to deliver a local anesthetic such as lidocaine (Xylocaine) before a bronchoscopy procedure.

3. Contraindications

a. An untreated pneumothorax is listed by all authors and the AARC guidelines as an absolute contraindication. An increased intrathoracic pressure converts a simple pneumothorax into a tension pneumothorax. The consequences can be fatal. Once a chest tube has been inserted into the pleural space and a pleural drainage system set up, IPPB can be administered. There may be an increase in the air leak, but it will not be life-threatening.

The AARC guidelines list the following as relative contraindications. Any patient with one of the following contraindications should be evaluated carefully before a decision about the clinical use of IPPB is made:

b. Active hemoptysis

Expectoration of blood indicates that a tear has occurred in the airway or lung tissues. The IPPB treatment should be stopped if there is a large amount of hemoptysis. Certainly massive hemoptysis (defined as greater than 600 mL of blood expectorated in a 16-hour period) contraindicates IPPB.

c. Hemodynamic instability

d. Intracranial pressure greater than 15 mm Hg

e. Chest radiograph that shows a bleb

f. Tracheoesophageal fistula

g. Recent surgery on the esophagus, skull, face, or mouth

h. Untreated, active tuberculosis (hazard to the practitioner)

i. Nausea, air swallowing, or hiccups (singultation)

Exam Hint 14-2 (ELE, WRE)

Past examinations have included questions about the contraindications for IPPB, especially untreated pneumothorax or hemoptysis.

4. Hazards and precautions

The AARC guidelines list the following hazards and precautions for IPPB therapy:

a. Pneumothorax

b. Barotrauma

c. Increased airway resistance from a bronchospastic reaction to the positive pressure or an adverse reaction to a medication. This can result in alveolar overdistension and air trapping.

d. Hyperoxia when 100% oxygen is delivered to the patient. Some COPD patients who are hypercarbic and breathing on hypoxic drive may hypoventilate as a result.

e. Secretions that may become impacted when the inhaled gas is not humidified adequately

f. Nosocomial infection

g. Decreased venous return

h. Increased ventilation-to-perfusion mismatch. This may worsen any hypoxemia.

i. Hyperventilation

j. Psychologic dependence. This may be seen in the long-term home care patient who does not want to switch to another method of taking inhaled medications.

k. Hypocarbia

l. Hemoptysis

m. Gastric distension

n. Air trapping, auto-PEEP, or overdistended alveoli

5. Initiation of therapy

a. Steps in the basic procedure

1. Check for a complete and proper order specifying the patient, oxygen percentage, frequency of treatment, medication, and any special considerations.

2. Gather the necessary equipment, medication, and so on.

3. Assemble the equipment outside of the patient’s room.

4. Introduce yourself and the department you represent, and state your purpose to the patient.

5. Confirm the patient’s identity.

6. Have the patient sit up in bed or in a chair; an obese patient may stand.

7. Interview the patient.

8. Assess the patient’s vital signs.

9. Assess the patient’s breath sounds.

11. Instruct the patient to sip on the mouthpiece like a straw to turn the machine on. Have the patient relax and let the machine fill his or her lungs with air. The patient should hold his or her breath in for 2 to 3 seconds and exhale slowly.

b. Giving a passive treatment

Most authors describe the patient taking a passive treatment. In a passive treatment, the patient relaxes and lets the machine fill the lungs until the preset pressure is reached. As mentioned earlier, the patient is then told to hold in his or her breath before exhaling passively. This treatment is given with the intent of minimizing the patient’s WOB. As slow a flow rate as possible is used so that any nebulized medication is deposited deeply into the small airways and lungs.

c. Giving an active treatment

Several authors advocate having the patient take an active treatment in which he or she interacts with the IPPB machine to obtain as deep a breath as possible.

Welch and colleagues (1980) have found that the patient’s posttreatment IC is greatest when the practitioner (1) uses as high a peak pressure as the patient can tolerate and (2) coaches the patient to inhale as deeply as possible with the IPPB machine. They and others believe that this is the best way to treat or prevent atelectasis. Monitor the patient for signs of barotrauma/volutrauma.