AARC Clinical Practice Guideline: Effectiveness of Nonpharmacologic Airway Clearance Therapies in Hospitalized Patients

Assessment of Evidence

We sought to determine whether the use of nonpharmacologic ACT improves oxygenation, reduces length of time on the ventilator, reduces stay in the ICU, resolves atelectasis/consolidation, and/or improves respiratory mechanics versus usual care in 3 populations. The ACTs considered are listed in the Table. Because no high-level evidence was available and the recommendations are based on low-level evidence, we have not used a formal guideline development process such as the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system.¹⁵ Rather, the recommendations are based on a consensus of the committee, informed by a systematic review of the literature¹⁴ and clinical experience. The systematic review helped frame the issues and allowed for an identification of potential harms.

Hospitalized Adult and Pediatric Patients Without Cystic Fibrosis

Diseases such as pneumonia, bronchiectasis, COPD, and asthma have the potential to increase airway secretions, and endotracheal intubation can impair secretion clearance. Some patients are prescribed ACT for prophylaxis against symptomatic secretion retention (ie, ineffective gas exchange, atelectasis, dyspnea). Because of its historical prominence and frequent use, chest physiotherapy (CPT) has mistakenly been classified as the gold standard of ACTs.^16–18

The systematic review found no evidence from randomized controlled trials (RCTs) to support the use of ACTs to improve oxygenation, reduce length of time on the ventilator, reduce stay in the ICU, resolve atelectasis/consolidation, and/or improve respiratory mechanics versus usual care in this population.¹⁴ Some studies suggest that intrapulmonary percussive ventilation (IPV) may decrease stay in the ICU for non-intubated patients with COPD, but insufficient high-level evidence exists to support a recommendation for this therapy.^19,20

Guidelines from other groups also identified minimal evidence to support the use of ACT in hospitalized patients.^21,22 Based on lower levels of evidence, some guidelines recommend forced expiratory technique (FET) for COPD patients,²¹ active cycle of breathing technique (ACBT), and autogenic drainage for the treatment of bronchiectasis in adults,²² or oscillating positive expiratory pressure (PEP) for patients with COPD.²²

Adult and Pediatric Patients With Neuromuscular Disease, Respiratory Muscle Weakness, or Impaired Cough

There are many causes of respiratory muscle weakness and impaired cough, including neuromuscular disease (NMD), spinal cord injury, primary neurologic conditions, and generalized weakness. NMD covers a wide range of disorders, with varying onset, rates of progression, and patterns of muscle involvement. Many NMDs eventually involve the respiratory muscles.²³ Pulmonary complications are a well known cause of morbidity and mortality in these patients.²⁴ Inspiratory muscle weakness decreases the ability to breathe deeply, and expiratory muscle weakness decreases the ability to generate the sufficient intrathoracic pressure during exhalation to cough effectively. While mucus production may be normal, some patients with bulbar muscle involvement may aspirate, leading to airway obstruction and infection. Pediatric patients have the additional burden of lower functional residual capacity, increased airway closure, and smaller airway diameter.²³

No RCT met the criteria for inclusion in the systematic review.¹⁴ However, the American College of Chest Physicians,²¹ British Thoracic Society,²² American Association of Neurology,²⁵ Centers for Disease Control and Prevention,²⁶ and American Thoracic Society²⁷ have published guidelines that recommend various ACTs in certain situations. These guidelines are based on low-level evidence, and patient benefit is indeterminate. Issues surrounding ACTs in this population include the necessity of a caregiver for assistance, poor technique, tolerance, and lack of effectiveness in some patients.²¹

Several guidelines recommended manual and mechanical cough assist procedures for patients who have a weak cough.^{21,22,25,26,27} Mechanical insufflation-exsufflation was cautiously recommended for children with weak cough,²² strongly recommended in patients with Duchenne muscular dystrophy,^26,27 and recommended for patients with amyotrophic lateral sclerosis.²⁵ Based on low-level evidence, it has been suggested that therapy for cough assist should be initiated when peak cough flow is < 270 L/min.²⁷ Though frequently mentioned for management of patients with NMD, no high-level studies address CPT in this population. CPT is often not well tolerated or feasible in these patients. Previously reviewed guidelines do not report any recommendations related to CPT.^{21,22,25–27} PEP therapy is not recommended by any major medical society for the management of NMD patients. There are some RCTs involving IPV and high-frequency chest wall compression (HFCWC), but the sample sizes were small, and evidence to support or reject their use in this population is not sufficient.^28–30

Postoperative Adult and Pediatric Patients

Postoperative pulmonary complications occur in approximately 7% of patients with normal preoperative lung function, and more than 70% of those with increased risk factors such as advanced age, history of smoking, obesity, preexisting chronic lung disease, obstructive sleep apnea, type and duration of surgery, extent and location of surgical incision, and use of a nasogastric tube.^31–33 Upper abdominal and thoracic surgeries are associated with the highest complication rates. Postoperative pulmonary complications include atelectasis, respiratory failure, and airway infection. Although atelectasis is the most common complication, pneumonia is considered to be the main cause of increased mortality, and these can co-exist.³⁴ Shallow breathing and weak cough lead to retained secretions and are thought to be a primary contributor.^21,32 Therapies to address postoperative complications include lung volume expansion therapies (eg, incentive spirometry, intermittent positive-pressure breathing, CPAP) and secretion removal therapies (eg, CPT, HFCWC, IPV, PEP).³⁵

Incentive spirometry is one of the most common therapies ordered for postoperative patients at risk for postoperative pulmonary complications and in those who develop pneumonia and atelectasis. The systematic review¹⁴ did not include incentive spirometry, but several recent meta-analyses have been published on this topic. Cochrane systematic reviews found no evidence of benefit for the routine use of incentive spirometry in patients following coronary artery bypass graft³¹ or upper abdominal surgery.^32,36,37 Carvalho³⁴ et al came to similar conclusions in a review of 30 studies of patients recovering from abdominal, cardiac, and thoracic surgery.

The systematic review¹⁴ found that studies focused on CPT in this population did not demonstrate a reduction in the incidence of postoperative pulmonary complications, nor was there a decrease in hospital stay. Additionally, no improvement in pulmonary function (FEV₁, FVC, or peak expiratory flow) was reported with the addition of CPT to routine patient care.^38–44 The 2 studies of PEP therapy were contradictory, and therefore there is no clear evidence supporting the use of PEP therapy in this population.^39,44 However, it has been well documented that early patient mobilization in this population can reduce the incidence of complications.^45–47

The results of the systematic review¹⁴ are similar to other recent reviews. Pasquina et al³⁷ included 13 trials in a systematic review that compared physiotherapy to a no-intervention control group, and concluded that routine physiotherapy was not justified. Another systematic review of strategies to reduce pulmonary complications after non-cardiothoracic surgery concluded that the evidence suggests that any type of lung expansion intervention is better than no prophylaxis, but that no modality was superior to the others, and combined modalities may provide additional risk reduction.⁴⁸

Few if any of the studies in the postoperative population specifically evaluated airway clearance as an outcome. Given the low level of evidence for any ACT, no high-level recommendations can be made at this time.

Questions to Consider When Selecting an Airway Clearance Technique or Device for an Individual Patient

Despite the clinical observation that retained secretions are detrimental to respiratory function, and anecdotal associations between secretion clearance and improvements in respiratory function, there is a lack of high-level evidence to support any ACT. The results of the systematic review of RCTs by Andrews and colleagues¹⁴ are the same in each of the clinical settings evaluated. Specifically, for individuals without CF, the ACTs reviewed provide small benefits in pulmonary function, gas exchange, oxygenation, and need for or duration of mechanical ventilation, but differences between groups were generally small and not significant.

The Andrews et al¹⁴ report does not mean that the device choice for airway clearance in a specific patient does not matter. Given a lack of evidence, we suggest the following process and clinical hierarchy of questions to determine the need for and technique used to perform airway clearance therapy.¹²

1. Investigate the rationale for use of airway clearance therapy. Does the patient have difficulty clearing airway secretions? Are retained secretions affecting gas exchange or lung mechanics? Rather than focusing on the volume of expectorated secretions, attention should be placed on the difficulty the patient is having when attempting to mobilize and expectorate airways secretions. Available evidence does not support routine airway clearance therapy in postoperative patients, mechanically ventilated patients, or patients with COPD.

2. Evaluate the potential for adverse effects of therapy. Which therapy is likely to provide the greatest benefit with the least harm? The review by Andrews et al suggests that the risk of harm associated with the usual ACTs is low, although complications may be under-reported.¹⁴

3. Determine the cost of the therapy. What is the cost of the therapy in terms of the device cost and clinician time to apply or supervise the therapy? ACTs can be time consuming for hospital staff. Some devices are expensive for the equipment and supplies. This is particularly important when selecting a device or techniques to be used at home.

4. Inquire about patient preferences. What factors are important to the patient with regard to performing airway clearance therapy? Lacking high-level evidence that any technique is superior to another, patient preference is an important consideration.

When a decision is made to prescribe airway clearance therapy for a patient, the expected outcome and treatment period should be clearly articulated. Desired outcomes or goals for therapy might include an increased (or decreased) volume of expectorated sputum, an improvement in gas exchange, an improvement in radiographic findings, or an improvement in patient-reported symptoms such as dyspnea. If the therapeutic goal is not achieved in the specified time, the therapy should be discontinued. Performing ACT with an ambiguous clinical outcome and continuing the therapy without evidence of benefit is a waste of resources. An n-of-1 construct (multiple crossover studies in one individual) is attractive, but might be difficult to implement in the acute care setting.^49,50

When evidence from high-level RCTs is not available, decisions may be made based on clinical judgment. For example, there is a strong physiologic rationale for the use of airway clearance therapy in patients with NMD and a weak cough.⁵¹ Moreover, there are a number of observational studies supporting the use of cough assistive therapies in this patient population. Thus it is reasonable to recommend airway clearance therapy for these patients, with a goal of increased expectorated sputum, and the therapy should be continued if this goal is achieved.

Respiratory secretions trouble clinicians and patients, and standard practice calls for efforts to clear these from the lungs. An important proportion of respiratory therapists' (and others') time is spent in efforts to remove secretions from the lower respiratory tract. In recent years a variety of techniques for secretion clearance have become available. Despite clinical enthusiasm for many of these by both clinicians and patients, there is sparse high-level evidence demonstrating benefit from many of these techniques. As pointed out by Andrews et al,¹⁴ there are a number of methodological limitations of the published reports of secretion clearance techniques. Although lack of evidence does not mean lack of benefit, it is desirable to have better evidence to support the practice. Appropriately powered and methodologically sound research is needed. This provides an opportunity for respiratory therapists and others to conduct research on a very important aspect of our practice. To ensure effective therapy for patients and maximize healthcare resources, the scientific basis for airway clearance techniques must be improved.

Summary

Anecdotally, routine delivery of ACTs, most notably CPT, to non-CF, hospitalized patients is common. However, the burden of delivering prophylactic ACT (ie, potential complications, cost of therapy, overutilization of resources for both staff and patient finances) outweighs the perceived benefit. Indeed, no high-level evidence was found to substantiate significant benefit on any outcome from the use of ACT in this population.¹⁴ The use of routine prophylactic ACT cannot be supported.

With regard to the NMD population, ACT has traditionally targeted improved cough as a means to prevent and treat pulmonary morbidity. ACT techniques have also been employed during acute respiratory infections to mobilize secretions. However, there is a lack of high-level evidence supporting any of these techniques, despite a large number of observational reports, narrative reviews, and guidelines written on the subject. The Andrews et al¹⁴ systematic review found no trials meeting our criteria on the subject, with most research based on crossover or observational design, with small sample sizes, case studies, or anecdotal experience.

When cough is weak, cough assist techniques such as manual or mechanical assisted cough maneuvers may be beneficial.⁵² Low-level evidence from observational studies suggests that a peak cough flow greater than 160–270 L/min is necessary to generate an effective cough.^25,26 Though the measurement of peak cough flow is more definitive for identifying weak cough, the application of cough assist technique should also be based on the patient's ability to tolerate the therapy, and the effectiveness noted for each individual patient.

Following upper abdominal and thoracic surgery, important pulmonary complications pose substantial risks. Avoidance of these complications is the prudent approach with both appropriate intraoperative ventilation and a postoperative multi-faceted protocol.^53–57 ACT has been used for the prevention and treatment of postoperative pulmonary complications for many years. However, there are many causes of atelectasis,⁵⁸ and the use of ACT in the setting of atelectasis without retained airway secretions does not appear to be effective. This is particularly true in the setting of upper abdominal and thoracic incisions, where performing these maneuvers is likely to increase pain, which further impairs lung function and cough. Time honored therapies without sufficient evidence should be abandoned in favor of multi-faceted approaches that include patient education, collaborative care, and early ambulation.^53–57

Routine use of incentive spirometry cannot be supported as a therapy to prevent postoperative complications. CPAP by face mask can alleviate hypoxemia due to low tidal volumes and airway obstruction, and may avoid reintubation, but there is no high-level evidence that this improves airway clearance.⁵⁹ PEP therapy is seen as a simple and less expensive alternative to CPAP. However, the routine use of PEP has no high-level evidence supporting its use, other than in patients with CF.

Respiratory therapists and others on the healthcare team must face the reality that the ACTs commonly provided for hospitalized patients lack support from high-level studies. In this time of cost containment, we are obliged to provide therapy for which there is sufficient evidence for benefit. This lack of evidence for a commonly administered therapy should sound the siren for clinicians, academic institutions, and funding agencies to collaborate on well designed studies to determine which ACTs are beneficial for hospitalized patients.