Intermittent Positive-Pressure Breathing

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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

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 (VT) should be greater than normal when enhanced by IPPB. This greater-than-normal VT 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:

5. Initiation of therapy

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.

7. Initial settings on the Bennett PR-2

The PR-2 is used as the model respirator of the Bennett series. (Although the PR-2 is no longer being manufactured, many are still in clinical use.) Other Bennett units have slightly different controls and features. Refer to Figures 14-2 and 14-3 for the following:

Details on the design and control specifications for the various Bird and Bennett models can be found in the manufacturers’ literature and books on respiratory therapy equipment.

MODULE B

1. Change the patient-machine interface