Lung Expansion Therapy PDF

43 Lung Expansion Therapy Daniel F. Fisher CHAPTER OBJECTIVES After reading this chapter you will be able to: List the indications, ha ards, and complications associated nderstand the causes of atelectasis with the various modes of lung expan...

43 Lung Expansion Therapy Daniel F. Fisher CHAPTER OBJECTIVES After reading this chapter you will be able to: List the indications, ha ards, and complications associated nderstand the causes of atelectasis with the various modes of lung expansion therapy. dentify which patients are at the greatest risk for Describe the primary responsibilities of the respiratory developing atelectasis and needing lung expansion therapy. therapist in planning, implementing, and evaluating lung Define the clinical findings seen in atelectasis. expansion therapy. Describe how lung expansion therapy is able to reverse atelectasis. CHAPTER OUTLINE Causes and Types of Atelectasis, 937 Incentive Spirometry, 939 Initiation of Therapy, 948 Factors Associated with Causing Noninvasive Ventilation, 942 Preliminary Planning, 948 Atelectasis, 937 Intermittent Positive Airway Pressure Evaluating Alternatives, 948 Clinical Signs of Atelectasis, 938 Breathing, 942 Discontinuing and Follow-up, 948 Lung Expansion Therapy, 938 Continuous Positive Airway Posttreatment Assessment, 948 Baseline Assessment, 939 Pressure, 944 Selecting an Approach, 948 Early Mobilization of the Other Therapies, 947 Patient, 939 Positive Airway Pressure, 947 KEY TERMS atelectasis egophony lobar atelectasis compression atelectasis gas absorption atelectasis noninvasive ventilation (NIV) continuous positive airway pressure incentive spirometry (IS) high-flow nasal cannula (HFNC) (CPAP) intermittent positive airway pressure positive expiratory pressure (PEP) deep breathing/directed cough breathing (IPPB) Pulmonary complications are common serious problems seen in pulmonary function by maximizing alveolar recruitment and patients who have undergone thoracic or abdominal surgery.1,2 optimizing airway clearance. Such complications include atelectasis (alveolar collapse), pneu- Various lung expansion therapies can be effective in prevent- monia, and acute respiratory failure. These respiratory problems ing or correcting atelectasis in selected patients.1 There is no can be minimized or avoided if proper respiratory care is imple- one specific method to apply in a given situation because no mented during the perioperative period. The most common form advantage of any one method has been established. In fact, evi- of therapy used in high-risk patients is lung expansion therapy. dence suggests that patient preference is as important as the Lung expansion therapy encompasses a variety of respiratory chosen therapy.3 The most efficient use of resources is a primary care procedures designed to prevent or correct atelectasis. The concern with any plan to apply lung expansion therapy. most common modalities include early patient mobilization, All of the following therapies share a common goal, to increase deep breathing/directed cough, incentive spirometry (IS), con- functional residual capacity (FRC). In other words, all of these tinuous positive airway pressure (CPAP), positive expiratory supplemental techniques are designed to simulate a deep breath pressure (PEP), intermittent positive airway pressure breathing or sigh. In consultation with the prescribing physician, the respi- (IPPB), and high-flow nasal cannula (HFNC). The common ratory therapist (RT) should assist in identifying patients most purpose that all of these techniques share is improving likely to benefit from lung expansion therapy, recommend and 936  CHAPTER 43 Lung Expansion Therapy 937 initiate the appropriate and most efficient therapeutic approach, Impairment of the function of pulmonary surfactant can also monitor the patient’s response, and alter the treatment regimen have an impact on the development of atelectasis. Surfactants as needed. decrease the surface tension of the walls of the alveoli. When there is deterioration of surfactant function or amount of this vital protein, the resulting increase in surface tension can cause alveoli to collapse.5 CAUSES AND TYPES OF ATELECTASIS Most postoperative patients also have problems coughing Although atelectasis can occur from a large variety of problems, effectively because of their reduced ability to take deep breaths. this chapter focuses on the two primary types associated with An ineffective cough impairs normal clearance mechanisms and postoperative or bedridden patients who are breathing sponta- increases the likelihood of retained secretions, which could lead neously without mechanical assistance: (1) gas absorption atel- to the development of absorption atelectasis and pneumonia in ectasis and (2) compression atelectasis. Gas absorption atelectasis a patient with excessive mucus production. Patients with a history can occur either when there is a complete interruption of ven- of lung disease that causes increased mucus production (e.g., tilation to a section of the lung or when there is a significant chronic bronchitis) are most prone to develop complications in shift in ventilation/perfusion (V̇ /Q̇ ). Gas distal to an obstruction the postoperative period. Similarly, a significant history of ciga- is absorbed by blood passing through the pulmonary capillaries, rette smoking should alert the RT to the high risk for respiratory which eventually causes partial collapse of the nonventilated complications after surgery. Such patients must be identified in alveoli. When ventilation is compromised in a larger airway or the preoperative period and considered strong candidates for bronchus, lobar atelectasis can develop. airway clearance and lung expansion therapy. Elective surgery Compression atelectasis occurs when the transthoracic pres- for these patients may need to be postponed in some cases until sure (the pressure difference between the body surface and the such therapies can be included in the treatment plan. Lung expan- alveoli) exceeds the transalveolar pressure (PAL) (the pressure sion therapy in the postoperative period may help to improve difference between the alveoli and pleural space).2,4,5 Compres- clearance of secretions by improving the effectiveness of coughing sion atelectasis is primarily caused by mechanisms that increase and secretion removal. this pressure gradient. This situation is common with general anesthesia, with the use of sedatives and bed rest, when deep RULE OF THUMB breathing is painful, as when broken ribs are present or surgery has The closer the incision is to the diaphragm, the greater the risk for postopera- been performed on the upper abdominal region, and in morbidly tive atelectasis. Patients with a history of inadequate nutritional intake, as obese patients. Weakening or impairment of the diaphragm can shown by an albumin level less than 3.2 mg/dL, have an increased risk for also contribute to compression atelectasis. Compression atelec- pulmonary complications in the postoperative period. This increased risk is tasis also results from fluid overload. It is a common cause of most likely due to inadequate strength of the inspiratory muscles to maintain atelectasis in hospitalized patients. It may occur in combination a normal vital capacity (VC). with gas absorption atelectasis in a patient with excessive airway secretions who breathes with small tidal volumes for a prolonged Laparoscopic surgery uses a scope inserted through small inci- period and in the presence of expiratory flow limitation. sions to perform the procedure. se of this technique has gained widespread acceptance in gastrointestinal procedures because of Factors Associated With Causing Atelectasis shortened recovery time, less pain for the patient, and smaller Patients who have difficulty taking deep breaths without assis- incisions. All of these factors also lessen the opportunities for tance include those with significant obesity, patients with neu- developing postoperative pulmonary complications.8,9 romuscular disorders, patients under heavy sedation, and patients who have undergone upper abdominal or thoracic surgery. Diaphragmatic position and function are major contributors to MINI CLINI atelectasis. In an anesthetized patient, there is a cephalad (toward Risk Factors for Atelectasis the head) shift of the diaphragm. For patients who are supine Problem and breathing spontaneously, the lower, dependent portion of The RT is called to evaluate a 47-year-old obese man admitted to the hospital the diaphragm performs the most movement. The opposite occurs for upper abdominal surgery. He has a 60 pack-year smoking history and is scheduled for surgery tomorrow morning. Examination reveals bilateral inspira- in patients who are paralyzed—the upper portion of the dia- tory and expiratory coarse crackles and expiratory wheezes. He is alert and phragm is primarily involved in movement.4,5 Patients undergoing oriented with normal vital signs. His past medical history is positive for diabetes lower abdominal surgery are at relatively less risk for developing and kidney stones. What factors are present that predispose this patient to atelectasis than patients undergoing upper abdominal or thoracic postoperative atelectasis? What treatment plan should the RT recommend? surgery. Neuromuscular injury patients are prone to respiratory complications, the most common of which is atelectasis. Atel- Discussion ectasis can occur in any patient who cannot or does not take Several important risk factors are present in this patient. The three most deep breaths periodically and in patients who are restricted to important are the patient’s history of smoking, obesity, and the upper abdominal bed rest for any reason.6 Atelectasis is one of the leading causes site of surgery. The findings of adventitious lung sounds and positive smoking history are very suggestive of a current pulmonary problem that would probably of hypoxemia after abdominal surgery and may account for 24% require bronchial hygiene and bronchodilators before surgery. Postoperatively, of deaths within 6 days of surgery.7 It is good clinical practice this high-risk patient would need careful monitoring for risks of atelectasis. to consider atelectasis during assessment of postoperative patients. 938 SECTION V Basic Therapeutics vessels, and air bronchograms. Indirect signs include: elevation CLINICAL SIGNS OF ATELECTASIS of the diaphragm; shift of the trachea, heart, or mediastinum; RTs must be able to recognize the clinical signs of atelectasis in pulmonary opacification narrowing of the space between the patients so that appropriate therapy can be implemented in a ribs; and compensatory hyperexpansion of the surrounding lung. timely fashion. The patient’s medical history often provides the first clue in identifying atelectasis. Recent upper abdominal or thoracic surgery in any patient should suggest possible atelectasis. LUNG EXPANSION THERAPY A history of chronic lung disease or cigarette smoking or both All modes of lung expansion therapy increase lung volume by provides additional evidence that the patient is prone to respira- increasing the PAL gradient. As detailed elsewhere in this text tory complications after major surgery or prolonged bed rest. (Chapters 47 and 52), PAL gradient represents the difference between the alveolar pressure (Palv) and the pleural pressure (Ppl): MINI CLINI PAL = Palv − Ppl Physical Signs of Atelectasis With all else being constant, the greater the PAL gradient, the Problem more the alveoli expand. How does a patient with atelectasis present during a physical assessment? As depicted in Fig. 43.1, the PAL gradient can be increased by Discussion either: (1) decreasing the surrounding Ppl (see Fig. 43.1A) or (2) Depending on the severity of atelectasis, the patient could be lying in bed and increasing the Palv (see Fig. 43.1B). A spontaneous deep inspira- start to have a requirement for supplemental oxygen. On auscultation, the tion increases the PAL gradient by decreasing the Ppl. Applying breath sounds can range from shallow and distant. When asking the patient positive pressure to the lungs increases the PAL gradient by increas- to take a deep breath, you may hear faint crackles and see an improvement ing the pressure inside the lung (Palv). in oxygen saturation. All lung expansion therapies use one of these two approaches. Moderate atelectasis can present itself with an increase in respiratory rate IS enhances lung expansion through a spontaneous and sustained and a consistently lower SpO2. Breath sounds may have definite crackles and decrease in Ppl. Positive airway pressure techniques increase Palv you may also hear occasional bronchial breath sounds. in an effort to expand the lung. Positive pressure lung expansion Severe atelectasis can present by having the patient complain of dyspnea, requiring an increasing amount of oxygen and absent breath sounds over the therapies may apply pressure during inspiration only, during affected area with distinct bronchial breath sounds in the surrounding margins. expiration only (as in HFNC, PEP, and flutter valves), or during both inspiration and expiration (CPAP). IS and other patient- directed therapies require an alert, cooperative patient who is The physical signs of atelectasis may be absent or very subtle capable of taking a deep breath. if the patient has minimal atelectasis. When the atelectasis involves The goal of any lung expansion therapy should be to imple- a more significant portion of the lungs, the patient s respiratory ment a plan that provides an effective strategy in the most efficient rate increases proportionally. ine, late-inspiratory crackles may manner. Staff time and equipment are the two major issues related be heard over the affected lung region. These crackles are pro- to efficiency. or a patient with minimal risk of postoperative duced by the sudden opening of distal airways with deep breath- atelectasis, deep breathing exercises, frequent repositioning, and ing. Bronchial-type breath sounds may be present as the lung early ambulation are usually effective and can be done with becomes more consolidated with atelectasis. Diminished breath minimal coaching and time from clinicians and without equip- sounds are common when excessive secretions block the airways ment.5 or a patient at high risk for atelectasis e.g., a patient and prevent transmission of breath sounds. Another lung sound undergoing upper abdominal surgery), IS is usually instituted. that may be present with consolidation is egophony. The con- The additional staff time and equipment are justified in this solidated tissue will decrease transmission of the higher-frequency high-risk group. Positive pressure therapy requires significantly lung sounds. Egophony has also been considered to be present more staff time and equipment and is reserved for high-risk if, when asked to say the letter “E,” the patient sounds to the patients who cannot perform IS techniques. practitioner as if he or she were saying “Aaay.” Tachycardia may be present if atelectasis leads to significant hypoxemia. RULE OF THUMB There is a direct relationship between the spontaneous respiratory rate and the degree of atelectasis present. Typically, as atelectasis progresses, respira- tory rate increases proportionally. The chest x-ray is often used to confirm the presence of atel- ectasis. The atelectatic region of the lung has increased opacity. Evidence of volume loss is present in patients with significant A B atelectasis. Direct signs of volume loss on the chest film include Fig. 43.1 Transalveolar pressure gradients with spontaneous inspiration displacement of the interlobar fissures, crowding of the pulmonary (A) and positive pressure inspiration (B).  CHAPTER 43 Lung Expansion Therapy 939 Baseline Assessment Although early mobilization does not classify as a procedure, Before beginning therapy, a baseline patient assessment should it does have distinct benefits in decreasing morbidity and mor- be conducted. This information helps to individualize the treat- tality.12,14,18,19 Early mobilization is a true multidisciplinary ment and allows objective evaluation of the patient’s subsequent approach that requires the various members of the healthcare response to therapy. Together with the patient’s medical history, team (RT, nurse, physical therapist) to be present at the same this baseline assessment also alerts the RT to possible problems time. aving the patient get out of bed and walk will improve or hazards associated with administering any therapy to the ventilation and perfusion, which will prevent or lessen the occur- patient. The baseline assessment includes a general evaluation rence of developing atelectasis, making the need for the following of the patient s clinical status and a specific assessment related therapies less likely. to the chosen therapeutic goals. The general assessment, common to all patients for whom respiratory care is ordered, includes: RULE OF THUMB—EARLY MOBILIZATION (1) measuring vital signs, (2) assessing the patient’s appearance Many of the techniques described in this chapter—IS, CPAP, IPPB, and PEP— and sensorium, (3) assessing the breathing pattern through chest simulate normal function if the patient were to be standing and walking. All auscultation, and (4) the patient’s level of motivation and their are strong arguments for early mobilization. So get your patients out of bed ability to follow instructions. and help them walk! Early Mobilization of the Patient Intensive Care Unit Patient Incentive Spirometry Evidence supports that it is better for the overall recovery of The purpose of S is to coach the patient to take a sustained patients to get them out of bed and provide early ambulation.10-13 maximal inspiratory (SMI) effort resulting in a decrease in PAL and The complications of prolonged bed rest include cardiovascular, maintaining the patency of airways at risk for closure. Because of pulmonary, gastrointestinal, and skin integrity issues. Pulmonary its simplicity, IS has been the mainstay of lung expansion therapy complications of immobility include: development of atelecta- for many years. IS devices are designed to mimic natural sighing sis, pneumonia, and pulmonary emboli (PE).11-13 Rates of early by encouraging patients to take slow, deep breaths simulating mobili ation for intensive care unit C patients have been a yawn or sigh. IS can be performed using devices that provide increasing in both Europe and the nited States, along with visual cues to patients when the desired inspiratory flow or volume an emphasis on decreasing morbidity in the C. Mobili a- has been achieved. S was first described in , which led to tion includes not only walking but also sitting, standing, and the development of a visual feedback device in 3.20 getting out of bed into a chair. As the patient changes body The desired volume and number of repetitions to be performed position, his or her breathing changes, as does the gas distribu- are initially set by the RT or other qualified caregiver. The inspired tion within the lung. Improvements in ventilation results in less volume goal is set on the basis of predicted values or observation alveolar collapse. of initial performance. The true benefit from S is best achieved Because of the beneficial pulmonary effects of early mobili a- by repeated use and proper technique.21 tion of the post–abdominal surgery patient, it has been suggested that mobilization should be considered as early as the day of Physiologic Basis surgery.14 With the increasing knowledge of the benefits of early A sustained maximal inspiration is functionally equivalent to mobili ation, the paradigm must change from thinking that a performing an FRC to inspiratory capacity (IC) maneuver, fol- patient is too sick to get out of bed to one in which we must lowed by a breath hold. Fig. 43.2 compares the alveolar and Ppl think that a patient is too sick to stay in bed.13 changes occurring during a normal spontaneous breath and an To move patients from the bed, it is important that they are SMI during IS. not completely sedated. Along with early mobilization, there are During the inspiratory phase of spontaneous breathing, the other benefits of lighter sedation and even “sedation vacations” decrease in Ppl caused by expansion of the thorax is transmitted when all sedation for the patient is temporarily discontinued in to the alveoli. With Palv now negative, a pressure gradient is created order to reassess the need for sedation. Having a patient who is between the airway opening and the alveoli. This transrespira- able to respond to the caregiver allows for better pain control tory pressure gradient causes gas to flow from the airway into with decreased risk of sedation-related complications.15,16 the alveoli. Within certain limits, the greater the transrespiratory pressure gradient, the more lung expansion occurs. Non–Intensive Care Unit Patient aving a non- C patient mobili e frequently may not have the technical roadblocks that are seen in the C such as multiple RULE OF THUMB—INCENTIVE SPIROMETRY intravenous (IV) pumps, cardiovascular support devices (intra- IS was first developed as a simulated yawn. It was noted that as the patient aortic balloon pumps, ventricular assist devices, impella, or even yawns (sighs), oxygenation improves. extracorporeal membrane oxygenate [ECMO]),17 but there is a personnel cost to moving the patient. The patient-nurse ratio is typically larger on the general medicine/surgery floors than Indications in the C. The availability of support staff will also need to be Indications for IS are listed in Box 43.1. The primary indication coordinated. for IS is to treat existing atelectasis. IS may also be used as a 940 SECTION V Basic Therapeutics BOX 43.3 Hazards and Complications of Incentive Spirometry + Hyperventilation and respiratory alkalosis Discomfort secondary to inadequate pain control A B Pulmonary barotrauma Exacerbation of bronchospasm Pressure 0 Fatigue – Acute respiratory alkalosis is the most common problem and occurs when the patient performs IS too rapidly or if the pre- scribed frequency of therapy is mismatched.22 Dizziness and numbness around the mouth are the most frequently reported symptoms associated with respiratory alkalosis. This can be easily corrected with careful instruction and monitoring of the patient. Inspiration Expiration Inspiration Expiration Discomfort with deep inspiratory efforts due to pain is usually the result of inadequate pain control in a postoperative patient. Appropriate pain control before and during therapy is important. Fig. 43.2 Alveolar (solid lines) and pleural (dotted lines) pressure changes during spontaneous breathing (A) and sustained maximal inspiration (B). Equipment Note the difference in transalveolar pressure (PAL) gradients (double The original IS devices were electronic and provided the user arrows). with visual feedback even though the equipment needed for SMI is typically simple, portable, and inexpensive. Although BOX 43.1 Indications for Incentive advances in technology have produced more complex devices, Spirometry there is no evidence that these devices produce any better out- comes than their lower-cost, disposable counterparts. Presence of pulmonary atelectasis IS devices can generally be categorized as volume oriented Presence of conditions predisposing to atelectasis or flow oriented. True volume-oriented devices measure and Upper abdominal surgery visually indicate the volume achieved during an SMI. The most Thoracic surgery Surgery in patients with COPD popular true volume-oriented IS devices use a bellows that rises Presence of a restrictive lung defect associated with quadriplegia or dys- according to the inhaled volume. When the patient reaches a functional diaphragm target inspiratory volume, a controlled leak in the device allows the patient to sustain the inspiratory effort for a short period COPD, Chronic obstructive pulmonary disease. (usually 5 to 10 seconds). Because the bellows types of IS devices are bulky and large, smaller devices that indirectly indicate volume BOX 43.2 Contraindications to Incentive based on ow through a fixed orifice have been developed. These Spirometry devices sacrifice accurate measurement of the inhaled volume for portability and smaller size (Fig. 43.3). Patient cannot be instructed or supervised to ensure appropriate use of Flow-oriented devices measure and visually indicate the degree device of inspiratory flow (Fig. 43.4). This flow can be equated with Patient cooperation is absent, or patient is unable to understand or dem- volume by assessing the duration of inspiration or time (flow onstrate proper use of device Patient is unable to deep breathe effectively (VC < 10 mL/kg or IC < 13 of × time = volume). Both flow-oriented and volume-oriented predicted) devices attempt to encourage the same goal for the patient: an SM effort to prevent or correct atelectasis. There is no benefit IC, Inspiratory capacity. of one type of IS over the other. preventive measure when conditions exist that make the devel- Administration opment of atelectasis likely.7 The successful application of IS involves three phases: planning, implementation, and follow-up. Because many of the components Contraindications of this process are similar to those previously described, we IS is a simple and relatively safe modality. For this reason, con- highlight only the key points and differences in approach. traindications are few (Box 43.2). Preliminary planning. During preliminary planning, the need for IS should be determined by careful patient assessment. Once Hazards and Complications the need is established, planning should focus on selecting specific Given its normal physiologic basis, IS presents few major hazards therapeutic outcomes. Box 43.4 lists potential outcomes that can and complications; those that can occur are listed in Box 43.3. be considered for patients receiving IS.  CHAPTER 43 Lung Expansion Therapy 941 Patients scheduled for upper abdominal or thoracic surgery should be screened before undergoing the surgical procedure. Assessment conducted at this point helps to identify patients at high risk for complications and allows determination of their baseline lung volumes and capacities. This approach provides an opportunity to orient high-risk patients to the procedure before undergoing surgery, increasing the likelihood of success when IS is provided after surgery. Implementation. Successful IS requires effective patient teach- ing. The RT should set an initial goal that is attainable by the patient yet requires a moderate effort. Setting an initial goal that is too low for the patient results in little incentive and an ineffective maneuver, at least initially. The patient should be instructed to inspire slowly and deeply to maximize the distri- bution of ventilation. The RT should watch the patient perform the initial inspira- tory maneuvers and ensure the patient uses correct technique. Fig. 43.3 Volumetric Incentive Spirometer. (Courtesy DHE Healthcare, Correct technique calls for diaphragmatic breathing at slow to Canastoga, NY.) moderate inspiratory flows. Demonstration is probably the most effective way to assist patient understanding and cooperation. Both the operation of the device and the proper breathing tech- nique can be explained easily when the RT uses himself or herself as an example, and much trial and error can be avoided. Many patients have difficulty with the slow inspiration fol- lowed by the breath hold. Nonetheless, patients should be encour- aged to try not to breathe in too fast or slowly and to attempt a brief breath hold. A normal exhalation should follow the breath hold, and the patient should be given the opportunity to rest as long as needed before the next SMI maneuver. Some patients in the early post- operative stage may need to rest for 30 seconds to 1 minute between maneuvers. This rest period helps to avoid a common tendency by some patients to repeat the maneuver at rapid rates, causing respiratory alkalosis. The goal is not rapid, partial lung inflation but intermittent, maximal inspiration. The exact number of sustained maximal inspirations needed to reverse or prevent atelectasis is not known and probably varies according to the patient’s clinical status. In fact, numer- ous studies have failed to report a standard frequency for either number of breaths per session or even how often to repeat the exercise during the day.23 However, because healthy individu- als average approximately six sighs per hour, an IS regimen Fig. 43.4 Flow-Oriented Incentive Spirometer. (From DeWit S: Funda- should focus on ensuring a minimum of 5 to 10 SMI maneuvers mental concepts and skills for nursing, ed 2, St Louis, 2004, Saunders.) each hour.22 Follow-up. Assessing the patient’s performance is vital to ensuring achievement of goals. To do so, the RT should make return visits to monitor treatment sessions until the correct technique and appropriate effort are achieved. Suggested moni- BOX 43.4 Potential Outcomes of Incentive toring activities for IS are outlined in Box 43.5. Spirometry After the patient has demonstrated mastery of technique, IS Decrease or elimination of atelectasis may be performed with minimal supervision. For patients with Improved breath sounds a neuromuscular disease or spinal injury, the use of a mechani- Normal or improved chest x-ray cal cough device (insufflator-exsufflator) (see Chapter 44) may Increased SpO2 provide a similar therapeutic objective. There is a lack of sup- Increased VC porting data that IS has an effect of preventing or reversing Improved inspiratory muscle performance and cough pulmonary complications in post-cardiac surgical patients or in SpO2, Oxygen saturation. those patients who have recently had upper abdominal surgery.20,24 942 SECTION V Basic Therapeutics BOX 43.5 Monitoring Patients Receiving BOX 43.6 Clinical Situations Incentive Spirometry Contraindicating Intermittent Positive Observe patient performance and use: Airway Pressure Breathing Therapy Frequency of sessions Tension pneumothorax Number of breaths per session ICP >15 mm Hg Volume and flow goals achieved Hemodynamic instability Breath hold maintained Active hemoptysis Effort and motivation Tracheoesophageal fistula Periodic observation of patient compliance, with additional instruction as Recent esophageal surgery needed Radiographic evidence of blebs Device within reach of patient and patient encouraged to perform Recent facial, oral, or skull surgery independently Singultus (hiccups) Vital signs and breath sounds Nausea ICP, Intracranial pressure. Noninvasive Ventilation Noninvasive ventilation (NIV) provides breathing support to patients with inadequate ability to ventilate. NIV has been docu- A B mented to have beneficial effects for patients who may need periodic, short-term support or patients who are experiencing exacerbations of pulmonary disease. N V offers some benefits over traditional, invasive ventilation due to lower infection risk and reduced need for sedation because of the absence of an Pressure artificial airway. N V is discussed in detail elsewhere Chapter 50). In addition, variations of NIV, including IPPB, CPAP, HFNC, and PEP therapy, can be potentially valuable lung expansion tools and are discussed in the following sections. Intermittent Positive Airway Pressure Breathing Physiologic Basis Inspiration Expiration Inspiration Expiration IPPB is a specialized form of NIV used for relatively short treat- ment periods (approximately 15 minutes per treatment). The Fig. 43.5 Alveolar (solid lines) and pleural (dotted lines) pressure changes intent of PPB, unlike N V, is not to provide full ventilatory support during spontaneous breathing (A) and intermittent positive airway pres- but to provide machine-assisted deep breaths assisting the patient sure breathing (B). Note the difference in transalveolar pressure (PAL) to deep breathe and stimulate a cough. This section discusses the gradients (double arrows). use of IPPB as a modality for the treatment of atelectasis. IPPB has historically consisted of providing an aerosol under can be useful in the treatment of pulmonary complications or positive pressure, augmenting the patient’s own inspiratory efforts exacerbations of lung disease.12,15-17 IPPB should not be used as and thus resulting in a larger tidal volume (VT) than could be a single treatment modality for a patient with absorption atel- spontaneously generated. The effectiveness of IPPB as an enhance- ectasis because of excessive airway secretions. Appropriate systemic ment for aerosol delivery has been shown to be incorrect. In hydration and airway clearance techniques should be used to fact, IPPB does not improve aerosol deposition at all.3 The Ameri- assist in removal of excessive secretions. can Association for Respiratory Care (AARC) clinical practice In concept, IPPB treatment should provide the patient with guidelines (CPG) for IPPB even recommends a 10-fold increase augmented tidal volumes, achieved with minimal effort. There in medication dosage when compared with other aerosol delivery are no data to support the use of IPPB as a method of preventing or methods.14 Lung volumes are increased in PPB because Palv > expanding atelectasis. The techniques listed later are more effective. Ppl. Depending on the mechanical properties of the lung, Ppl may exceed atmospheric pressure during a portion of inspira- Contraindications tion. As with spontaneous breathing, the recoil force of the lung, There are several clinical situations in which IPPB should not stored as potential energy during the positive pressure breath, be used (Box 43.6). With the exception of untreated tension causes a passive exhalation. As gas flows from the alveoli out to pneumothorax, most of these contraindications are relative. A the airway opening, Palv decreases to atmospheric level, while Ppl patient with any of the conditions listed in Box 43.6 should be is restored to its normal subatmospheric range (Fig. 43.5). carefully evaluated before IPPB therapy is begun. Indications Hazards and Complications Although IPPB is not an effective aerosol delivery system, periodic As with any clinical intervention, certain hazards and complica- sessions of positive pressure ventilation provided noninvasively tions are associated with IPPB. These potential problems should  CHAPTER 43 Lung Expansion Therapy 943 BOX 43.7 Hazards and Complications BOX 43.8 Potential Outcomes of of Intermittent Positive Airway Intermittent Positive Airway Pressure Pressure Breathing Breathing Therapy Hyperventilation and respiratory alkalosis Decrease or elimination of atelectasis Discomfort secondary to inadequate pain control Improved breath sounds Pulmonary barotrauma Normal or improved chest x-ray Exacerbation of bronchospasm Increased SpO2 Fatigue Increased VC Improved inspiratory muscle performance and cough SpO2, Oxygen saturation. be addressed in the initial stages of planning for IPPB. The most common complication associated with IPPB is inducing respira- BOX 43.9 Monitoring Intermittent Positive tory alkalosis. This problem is easily avoided through proper Airway Pressure Breathing Therapy coaching of the patient before and during treatment. Another potential complication of IPPB is gastric distention; Machine Performance this occurs when gas from the IPPB device passes directly into the Sensitivity Peak pressure esophagus. Gastric distention is uncommon in an alert patient Flow setting but is a significant risk for an obtunded patient. Normally, the FiO2 esophagus does not open until a pressure of approximately 20 to 25 cm H2O has been reached. Gastric distension represents Patient Responsea the greatest risk in patients receiving PPB at high pressures. The Breathing rate and expired volume major hazards and complications of IPPB are listed in Box 43.7. Peak flow or FEV1/FVC% Pulse rate and rhythm (from electrocardiogram if available) Administration Sputum quantity, color, consistency, and odor Effective IPPB requires careful preliminary planning, individual- Mental function Skin color ized patient assessment and implementation, and thoughtful Breath sounds follow-up. Blood pressure Preliminary planning. During preliminary planning, the need SpO2 (if hypoxemia is suspected) for IPPB is determined and desired therapeutic outcomes are ICP (in patients for whom ICP is important) established. Box 43.8 lists potential accepted and desired outcomes Chest x-ray (when appropriate) of IPPB therapy. Not all the outcomes listed in Box 43.8 apply Subjective response to therapy to every patient. a Items should be chosen as appropriate for the specific patient. FEV1, Forced expiratory volume in 1 s; FVC, forced vital capacity; ICP, intracranial pressure; SpO2, oxygen saturation. RULE OF THUMB IPPB was once a mainstay therapy for respiratory care. Its nearest cousin, noninvasive ventilation, uses a mask. IPPB was generally given via a mouthpiece Evaluating alternatives. Before starting IPPB, the RT and and nose clips. prescribing physician must determine therapeutic objectives for the treatment and whether simpler and less costly methods might be as effective in achieving the desired outcomes. MINI CLINI Discontinuation and Follow-Up Problem Depending on the goals of therapy and condition of the patient, While covering a surgical step-down floor, you are called to provide IPPB with IPPB treatments typically last 10 to 15 minutes. Follow-up activi- a bland aerosol to help a patient with postoperative atelectasis. ties include posttreatment assessment of the patient, recordkeep- Discussion ing, and equipment maintenance. Because you are on the floor, you go to the patient’s room, introduce yourself, Posttreatment assessment. At the end of a treatment session, and assess their pulmonary status. After you have completed your evaluation, the patient assessment is repeated. As with the baseline assess- you speak with the physician who ordered IPPB to find out what his therapeutic ment, this follow-up evaluation has two components. A follow-up goals would be and you relay your evaluation of the patient. The physician evaluation should focus on determining any pertinent changes states that the patient has severe atelectasis and he is concerned about devel- in vital signs, sensorium, and breath sounds, with emphasis on oping pneumonia and wanted to try IPPB to help with lung recruitment and identifying possible untoward effects. secretion clearance. You make the suggestion to try CPAP and give a flutter Treatment frequency should be determined by assessing patient valve to the patient to use when not wearing the CPAP mask. The distending response to therapy (Box 43.9). For acute care patients, orders pressure from the CPAP will help to re-recruit the lung, while using PEP may aid secretion clearance by keeping the airways from collapsing on exhalation. should be reevaluated based on patient response to therapy at least every 72 hours or with any change of patient status. 944 SECTION V Basic Therapeutics BOX 43.10 Clinical Situations Contraindicating Continuous Positive Airway A B Pressure Therapy + Tension pneumothorax/untreated pneumothorax ICP >15 mm Hg Hemodynamic instability Pressure Active hemoptysis 0 Tracheoesophageal fistula Radiographic evidence of blebs Recent facial, oral, or skull surgery – Nausea Hypoventilation ICP, Intracranial pressure. RULE OF THUMB Inspiration Expiration Inspiration Expiration Many different types of interfaces can be used for CPAP therapy. They range from nasal prongs (common in neonates, Chapter 54), nasal masks, oronasal Fig. 43.6 Alveolar (solid lines) and pleural (dotted lines) pressures during masks, and helmets. The ideal interface is that which is comfortable for the spontaneous breathing (A) and continuous positive airway pressure (B). patient, does not produce excessive pressure on the face, and minimizes dead Note the difference in transalveolar pressure (PAL) gradients (double space (VD). arrows). Continuous Positive Airway Pressure Contraindications Physiologic Basis Intermittent use of CPAP for correcting atelectasis is contrain- Atelectasis causes a pulmonary shunt and contributes to impaired dicated when certain clinical situations exist. A patient who is gas exchange. For areas with a low ventilation and perfusion hemodynamically unstable is unlikely to tolerate CPAP for even (V̇ /Q) and an elevated FiO2, the patient is at risk for developing a short period. For those patients who are suspected to have gas absorption atelectasis, further complicating the situation.25 hypoventilation, NIV is usually a better option than CPAP. CPAP CPAP provides a distending pressure to reinflate the collapsed is also inappropriate when the patient has nausea, facial trauma, airways thus improving V̇ /Q. untreated pneumothorax, or elevated intracranial pressure (ICP). As can be seen in Fig. 43.6, CPAP elevates and maintains high alveolar and airway pressures throughout the full breathing cycle; Hazards and Complications this increases PAL gradient throughout both inspiration and expi- Most hazards and complications associated with CPAP are caused ration. Typically, a patient on CPAP breathes through a pres- by either the increased pressure or the apparatus (Box 43.10). surized circuit against a threshold resistor, with pressures The increased work of breathing caused by the apparatus can maintained between 5 cm H2O and 20 cm H2O. To maintain lead to hypoventilation and hypercapnia. An improperly fitted system pressure throughout the breathing cycle, CPAP requires mask can also have detrimental effects on the success of CPAP. a source of pressurized gas. Too large a mask will increase the VD.26 A mask that is too small would require being tightly strapped onto the patient’s face. This Indications would increase their chances of developing a pressure-related Although evidence supports the use of CPAP therapy in the wound. In addition, because CPAP does not augment spontane- treating postoperative atelectasis, as with all mechanical tech- ous ventilation, patients with an accompanying ventilatory insuf- niques, the duration of beneficial effects appears limited. The ficiency may hypoventilate when CPAP is applied. Barotrauma corresponding increase in FRC may be lost within 10 minutes is a potential ha ard of CPAP and is more likely to occur in a after the end of the treatment. For this reason, it has been sug- patient with emphysema and blebs. Gastric distension may occur, gested that CPAP should be used on a continuous basis until especially if CPAP pressures greater than 25 cm H2O are needed. the patient recovers. This condition may lead to vomiting and aspiration in a patient CPAP by mask also has been used to treat cardiogenic pul- with an inadequate gag reflex. A special case is the obese patient monary edema. In such patients, CPAP reduces venous return who may actually require high levels of CPAP to counteract the and cardiac filling pressures, which is helpful in reducing pul- weight of their abdomen on the diaphragm. monary vascular congestion. Lung compliance is improved, and the work of breathing is decreased. The improvement in lung Monitoring and Troubleshooting compliance and the removal of the edema from the alveoli will CPAP poses a risk of hypoventilation. Experience with long-term result in improved ventilation (decreased dead space VD/VT) and CPAP shows that patients must be able to maintain adequate thus a decrease in hypercapnia. elimination of carbon dioxide on their own if the therapy is to  CHAPTER 43 Lung Expansion Therapy 945 be successful. For these reasons, patients receiving CPAP must and correction of leakage associated with CPAP. The RT must be closely and continuously monitored for untoward effects. In also ensure that the flow is adequate to meet the patient’s needs addition, it is vital that the CPAP device be equipped with a with the use of CPAP systems. Flow adjustments are made by means to monitor the pressure delivered to the airways and carefully observing the airway pressure. Flow generally can be alarms to indicate the loss of pressure owing to system discon- considered adequate when the system pressure decreases no more nect or mechanical failure. There should also be a device allowing than 1 to 2 cm H2O during inspiration. for excessive pressure to be released (pop-off). These are essential components of any CPAP device (Box 43.11). Administration The development of new CPAP units and improvement on Early administration of CPAP has been found to be beneficial the interface itself have addressed some of the comfort issues for both reversing atelectasis and improving V̇ /Q. Equipment. CPAP is most commonly delivered using either specialized CPAP machines (Fig. 43.7) or ventilators. These devices allow for a more consistent level of positive pressure and provide BOX 43.11 Hazards and Complications the benefit of some level of patient monitoring. n the case where of Continuous Positive Airway C -level ventilators are used, this includes monitoring of respi- Pressure Therapy ratory rate, airway pressures, and alarms. In the event of a dis- connect or if the patient becomes apneic, the ventilator alarms Barotrauma, pneumothorax Nosocomial infection can provide a measure of safety not realized with a high-flow Hypercarbia system and resistor valve. Hemoptysis Procedures. Whether used on an intermittent or continuous Pressure ulcers from mask basis, CPAP is a complex and potentially hazardous approach Gastric distension to patient management. As with all therapies, the appropriate Impaction of secretions (associated with inadequately humidified gas mixture) CPAP level for a patient must be determined on an individual Impedance of venous return basis. Initial application and monitoring require a broader range Hypoventilation of knowledge and skill than is required for simpler modes of Increased VD lung expansion therapy (Box 43.12). Vomiting and aspiration Preliminary planning. As with all respiratory care, effective VD, Dead space. CPAP therapy requires careful planning, individualized patient Fig. 43.7 Various continuous positive airway pressure systems. See text for description. 946 SECTION V Basic Therapeutics BOX 43.12 Potential Outcomes of Continuous Positive Airway Pressure Therapy Improved VC Increased FEV1 or peak flow Enhanced cough and secretion clearance A D Improved chest x-ray Improved breath sounds Improved oxygenation Improved patient comfort FEV1, Forced expiratory volume in 1 s. C BOX 43.13 Monitoring Continuous Positive Airway Pressure Therapy B Device Performance Mask fit Set pressure Flow rate FiO2 Patient Responsea Breathing rate and expired volume Pulse rate and rhythm (from electrocardiogram if available) Mental function Skin color Breath sounds Fig. 43.8 Schematic of a high-flow nasal cannula system (A) air-oxygen Blood pressure blender, (B) humidifier, (C) circuit, (D) high-flow cannula. SpO2 (if hypoxemia is suspected) Ventilation ICP (in patients for whom ICP is important) Chest x-ray (when appropriate) BOX 43.14 Clinical Situations Subjective response to therapy Contraindicating High-Flow Nasal a Items should be chosen as appropriate for the specific patient. Cannula Therapy ICP, Intracranial pressure; SpO2, oxygen saturation. Hypercarbic respiratory failure Inability to protect the airway Unable to tolerate high flow assessment and implementation, and thoughtful follow-up (Box 43.13). Evaluating alternatives. The use of CPAP, NIV, or HFNC has shown promise in decreasing the development of postopera- care. The typical flow limit for these devices is approximately tive respiratory complications.27 L/min, which is a result of the upper airway to warm and humidify the inspired gas. Common patient complaints when Discontinuing and Follow-Up standard nasal cannulas are used at high flows are headache, Depending on the indications for CPAP (e.g., chronic heart failure drying of nasal mucosa, and nosebleeds (Fig. 43.8).26,28,29 [CHF]), once the underlying cause that indicated the need for The small inner diameter of the standard nasal cannula also CPAP has been addressed, it is possible to start to discontinue does not allow for higher flows. HFNC is specially designed with therapy. In the case of CHF, once the patient has been diuresed, larger prongs allowing higher oxygen flow rates. In addition they will most likely not need the positive pressure. Care for to the larger-bore cannula, the gas is also heated and humidi- other patients may result in periods of time off therapy followed fied before being delivered to the patient providing a higher by periods back on until the patient shows signs of continued level of comfort. These two factors allow for the flow rate to be improvement. significantly higher, ranging from 0 to 0 L/min Boxes 3. Posttreatment assessment. Auscultation of breath sounds and 43.15).28-30 and monitoring oxygen saturation (SpO2) in addition to patient assessment will help to guide the clinician. Physiologic Basis High-flow nasal cannula. Providing supplemental oxygen HFNC at elevated inspiratory flows provides a more stable FiO2. via a nasal cannula has been a common practice in respiratory Another benefit from the enhanced ow is washing out the CO2  CHAPTER 43 Lung Expansion Therapy 947 BOX 43.15 Hazards and Complications of BOX 43.17 Monitoring Continuous High-Flow Nasal Cannula Therapy Positive Airway Pressure Therapy Nosocomial infection Device Performance Hypercarbia Mask fit Headache Flow rate Drying of mouth/upper airway FiO2 Impaction of secretions (associated with inadequately humidified gas mixture) Patient Responsea Breathing rate Pulse rate and rhythm (from electrocardiogram if available) Mental function BOX 43.16 Potential Outcomes of High- Skin color Flow Nasal Cannula Therapy Breath sounds Improved chest x-ray Blood pressure Improved breath sounds SpO2 (if hypoxemia is suspected) Improved oxygenation Ventilation Improved patient comfort ICP (in patients for whom ICP is important) Chest x-ray (when appropriate) Subjective response to therapy a Items should be chosen as appropriate for the specific patient. from the anatomic dead space. This helps with ventilation because ICP, Intracranial pressure; SpO2, oxygen saturation. the CO2 contained in the nasal pharynx has been eliminated and is not the first gas that enters the lowers respiratory tract with each breath. Essentially, gas flow in the upper airway is unidirectional, in through the nose and out through the mouth. This reduces anatomic dead space by approximately one-third, Physiologic Basis reducing PCO2 by 3 to mm g and decreasing the work There are three current approaches to PAP therapy: PEP, flutter, of breathing.30 and CPAP. All three techniques are effective in treating atelectasis In addition to the washout, a small level of positive pressure in most postsurgical patients.32,33 sing either PEP or utter as is delivered as a result of resistance generated as with the patient part of airway clearance is described in detail in Chapter 44. breathing out against the high inspiratory flow. Most estimate This chapter focuses on the uses of PAP for treating atelectasis. that approximately 1 cm H2O positive end-expiratory pressure PEP threshold, resistor, and flutter valves create expiratory PEEP is established for every 0 L/min ow through the NC. positive pressure only without need for continuous flow or This low positive pressure will first help to recruit collapsed complex machinery,28 whereas CPAP maintains a positive airway alveoli by increasing the PAL and maintaining their inflation once pressure throughout both inspiration and expiration. Fig. 43.6 reopened.28,29 V̇ /Q will improve as a result of the improved ven- compares the alveolar and Ppl changes occurring during a normal tilation to previously perfused areas of the lung (Box 43.16). spontaneous breath (see Fig. 43.6A) and CPAP (see Fig. 43.6B). The following factors involving PAP, flutter, and CPAP therapy Other Therapies contribute to the beneficial effects recruitment of collapsed There are other therapies available to the RT with the aim of alveoli through an increase in RC, decreased work of breath- secretion clearance and possible treatment of postoperative pul- ing due to increased compliance or elimination of intrinsic monary complications: intrapulmonary percussive ventilation positive end-expiratory pressure (PEEPi), (3) improved distri- (IPV) and high-frequency chest wall compression (HFCWC). bution of ventilation through collateral channels (e.g., pores of There is a lack of supporting evidence for the effectiveness of Kohn , and increase in the efficiency of secretion removal either of these therapies, although each is similar to techniques (Box 43.17). previously discussed within this chapter. IPV is similar to IPPB with a high respiratory rate, and HFCWC is similar to chest Indications physical therapy (CPT) using a pneumatic vest that the patient The evidence for PEP therapy suggests that patients with expira- wears. These modalities are mentioned for completeness, although tory airflow limitation will best respond to this therapy.31,34 PEP the evidence supporting them is low-level or anectdotal.3,19 mimics the maneuver of pursed-lip breathing by presenting expiratory resistance either through a flow or threshold resistor, Positive Airway Pressure and an elongated expiratory phase. Those patients who are good irst introduced in Denmark during the 0s as an airway candidates for PEP therapy are those who can follow instructions clearance device, and similar to CPAP, PEP adjuncts use positive and repeat the demonstration back to the RT. pressure to increase the PAL gradient and enhance lung expan- Similar to IS, there is no set duration for therapy nor a set sion.31 In contrast to CPAP or HFNC, PAP therapy requires no number of repetitions during each session. Currently this therapy complex machinery. Some methods do not even need a source is given for patients who may either have atelectasis or have of pressurized gas. breathlessness. 948 SECTION V Basic Therapeutics Contraindications patient to carry them while outside of the hospital or home. Similar to the contraindications for the other lung expansion Many devices are now dishwasher safe for easier cleaning. therapies, an untreated pneumothorax should be considered before starting therapy. A good baseline assessment of the patient Evaluating Alternatives is helpful to identify any predisposing issues. If the patient cannot tolerate PEP, then alternative thera- pies could be either CPAP or HFNC. Both will aid in lung Hazards and Complications recruitment using a similar mechanism, with less patient Regardless if it is flow limited, a threshold device, or oscillating coordination. PEP, care should be taken that the patient does not hyperventilate during therapy. Signs can include dizziness, tingling in the Discontinuing and Follow-Up extremities, and light-headedness. In those cases, have the patient PEP therapy has been shown to have a positive effect on patient stop therapy until they feel better and then suggest a slower self-reported breathlessness for those patients who have non- regimen of breaths. cystic fibrosis bronchiectasis or severe chronic obstructive pul- monary disease (COPD).35 PEP can be continued at home as Equipment part of a daily regimen for pulmonary hygiene and dyspnea. PEP valve and mouthpiece. The device is designed to fit into a pocket and taken apart for cleaning. Posttreatment Assessment Procedures. Show the device to the patient and have them Auscultation of breath sounds and reviewing the patient diary take a tidal, or slightly larger than tidal, breath. ave the patient for shortness of breath can help to guide the RT in determining exhale through the PEP device and set the resistor to the desired if the therapy should be discontinued. strength. Repeat the instructions if they are breathing out too quickly or slowly.31,35 SELECTING AN APPROACH Monitoring and Troubleshooting Selecting an approach for lung expansion therapy requires Check the valve for obstructions if the patient cannot breathe in-depth knowledge of both the methods available and the spe- out from the device. Some PEP devices include a 30-day diary cific condition and needs of the patient being considered for that can be used to track progress. therapy. Fig. 43.9 presents a sample protocol for selecting an approach to lung expansion therapy. As indicated in the algorithm, the patient first must meet the criteria for therapy by having one MINI CLINI—PROBLEM WITH POSITIVE or more of the indications previously specified. or patients EXPIRATORY PRESSURE meeting the inclusion criteria, the RT first determines the degree of alertness. Because an obtunded patient cannot be expected to Problem cooperate with IS or PEP or expiratory positive airway pressure During a follow-up visit with a patient that you instructed in the use of PEP (EPAP) therapy, HFNC or CPAP is initiated with appropriate therapy, it is observed that the patient is struggling on exhalation through the monitoring. device and does not want to use it. or a patient having no difficulty with secretions, if the VC Discussion exceeds mL/kg of lean body weight or the C is greater than Looking at the device, you see that the resistance is set to maximum. The 33% of predicted, IS is given. If either the VC or the IC is less patient had visitors who were looking at the device and may have moved than these threshold levels, IPPB is initiated, with the pressure the setting. You take the time to provide some education and reassurance to gradually manipulated from the initial setting to deliver at least the patient and show how to set the resistance and enter it into the diary. mL/kg. f excessive sputum production is a compounding With the correct settings, the patient is more willing to continue therapy. factor, a trial of PEP therapy is substituted for IS. Based on patient response, bronchodilator therapy and bronchial hygiene measures may be added to this regimen. If monitoring fails to reveal improvement and atelectasis persists, a trial of CPAP should be considered. Because evidence of the effectiveness of CPAP is INITIATION OF THERAPY still contradictory, its use should be limited to treating atelectasis The best approach for achieving a given clinical goal is always after alternative approaches have been tried without success. the safest, simplest, and most effective method for an individual Whether or not to keep critically ill patients on complete bed patient. Selecting an approach for lung expansion therapy requires rest is being critically examined in the literature.22-27,36,37 The in-depth knowledge of both the methods available and the specific complications of prolonged bed rest include cardiovascular, condition and needs of the patient being considered for therapy. pulmonary, gastrointestinal, and skin integrity issues. Pulmonary complications of immobility include those that have been the Preliminary Planning focus of this chapter: development of atelectasis, pneumonia, Patient education and motivation are key to the success for this and PE.23-27,36 Rates of early mobili ation for C patients have therapy. The PEP devices are made to be portable and allow the been increasing in both Europe and the nited States, along  CHAPTER 43 Lung Expansion Therapy 949 At risk for atelectasis No No Awake Increased CO2 Yes No Neuromuscular Early mobilization disease Yes Yes No Signs of Hypoxia/ Cough assist/MIE PEP/flutter improvement? desaturation No Yes High flow No Noninvasivce Signs of nasal cannula ventilation improvement? (HFNC) (NIV) Yes No Signs of Consider escalating improvement? level of care Yes Yes Continue to monitor Fig. 43.9 Protocol for selecting an approach for lung expansion therapy. See text for details. PEP, Positive expiratory pressure. MIE, Mechanical insufflation exhalation. with the an emphasis on decreasing morbidity in the C. Mobi- Lung expansion therapy corrects atelectasis by increasing the li ation does not only include walking, but also sitting, standing, PAL gradient; this can be accomplished by deep spontaneous and getting out of bed into a chair. As the patient changes body breaths or by the application of positive pressure. position, his or her breathing changes, as does the gas distribu- The most common problem associated with lung expansion tion within the lung. Improvements in ventilation result in less therapy is the onset of respiratory alkalosis, which occurs alveolar collapse. when the patient breathes too quickly. RTs are responsible for implementing, monitoring, and docu- menting results of lung expansion therapy. SUMMARY CHECKLIST Atelectasis is caused by persistent ventilation with small tidal volumes or by resorption of gas distal to obstructed airways. 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