Noninvasive Ventilation for Acute Respiratory Failure

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It may be said without argument that noninvasive positive pressure ventilation (NPPV) or noninvasive ventilation (NIV) may very well be one of respiratory care’s greatest contributions to the survival and care of patients who present in respiratory distress and/or failure. From the more primitive flow generated CPAP devices to the new advanced bilevel positive airway pressure systems of today, NPPV is a life-saving technology in many clinical settings. In this article, we explore the use of NPPV in the setting of acute respiratory failure as supported by evidence from clinical trials and meta-analyses. Also presented are the impact of respiratory protocols on the use of NPPV, one hospital’s clinical NPPV protocol, and the use of NPPV in obstructive sleep apnea (OSA) patients in the postoperative setting.

Whether your patient presents with status asthmaticus, cardiogenic pulmonary edema, or a COPD exacerbation, NPPV is often the first choice for “rescuing” this patient and transitioning them into a more stable respiratory pattern and acid-base balance. Indications for NPPV are listed in Figure 1. Despite its mainstay as a clinical application, the application of NPPV has both strengths and weaknesses that have been identified through randomized clinical trials. One evaluation of NPPV in randomized trials indicates that for acute respiratory failure (ARF) associated with COPD, it is proven to reduce intubation rates and hospital mortality for patients in severe exacerbations of COPD. There is also evidence of its benefit in mild exacerbations, although the evidence is not as strong.¹ The authors of this particular study state that for COPD patients, “we recommend that NIV be the first line of therapy for those presenting with respiratory distress and respiratory acidosis.”¹ In another study looking at the utility of using NPPV with COPD patients, it was determined that exacerbations treated with NPPV had an increased survival rate at 6 months and at 1 year post therapy.² One meta-analysis focusing on ARF associated with acute cardiogenic edema concluded that CPAP statistically reduced the need for intubation and reduced mortality, but it did not decrease the incidence of myocardial infarction when compared to standard therapies such as diuretics, nitrates, and standard oxygen therapy alone. In comparison to CPAP, bilevel systems only demonstrated a reduction in the rate of intubation when compared to standard therapy. It is important to note that there was no significant difference of outcomes in the comparison of bilevel to CPAP.³ Therefore, the rivalry of CPAP versus bilevel for cardiogenic pulmonary edema lives on and may simply be a matter of patient comfort and/or compliance.

For patients who present with status asthmaticus, the evidence for NPPV success is less compelling. In the randomized controlled trials related to NPPV up until 2009, only two relate to asthma and only one is complete. The standard for monitoring asthma—the measurement of FEV₁—showed a more rapid improvement with patients who were treated using NPPV, although the evidence does remain weak.¹ A more recent report in 2010 evaluated FEV₁, inhaled medication use, ICU stay, and overall hospital stay.⁴ The study concluded that NIV reduced inhaled medication use, shortened both the ICU and hospital stay, and improved lung function more quickly than did standard therapy.⁴ This study isolated four instances where standard medical therapy failed and the patients improved with the application of NPPV.⁴

In Case of Emergency

Considering that most patients who present with respiratory failure do so within the emergency department (ED), what is the degree of use for NPPV in the ED setting? The ED is a unique clinical setting, an area of specialty in which the physician and the providers know little about the patient’s history, especially if they present as a true emergency. The presentation of patients in respiratory distress or acute respiratory failure requires management by a staff who has not only a strong clinical skill set, but also the ability to make rapid clinical decisions based on experience. Hess et al⁵ performed one study that presented a survey to 132 academic medical centers that had emergency medicine residencies. One emergency physician and one respiratory therapist from each institution were asked to complete the survey. The results of the survey indicate that there is room for improvement in the application of NPPV in the ED. NPPV was used only 20% of the time in only 66% of hospitals surveyed in regard to COPD. Compare this to an 80% application rate for COPD in the intensive care unit, and there lies a disparity. NPPV’s application for cardiogenic pulmonary edema was similar.

It is even more alarming that 17% of hospitals used NPPV less than 10% of the time for COPD exacerbations. Since the consensus for first line therapy of COPD exacerbation is NPPV, there is room for improvement. The barriers for NPPV in the ED were identified as poor physician familiarity, availability of a respiratory therapist, and availability of appropriate equipment in the ED.⁵ Each of these can be addressed through a commitment of resources and education to improve the outcomes for patients in acute respiratory failure.

One publication drew upon the work by Hess et al5 in addition to a study performed in Veterans Affairs hospitals. The conclusions from these two surveys were very supportive of one another, stating: “Physicians are much less trained on NPPV than the respiratory therapist.”⁶ This difference in knowledge of NPPV leaves the respiratory therapist as the patient’s advocate when considering the use of bilevel or CPAP. We have been in this position on numerous occasions, and it is a frustrating experience to take part in a most unwarranted procedure—intubation.

Just Who Is the Champion of NPPV?

From the evidence previously discussed, the respiratory therapist must accept the responsibility not only as practitioner, but also as educator on respiratory modalities and therapies in an effort to increase the knowledge base of all providers. This is an exciting opportunity for the respiratory therapist to create an exchange of information that could result in increased confidence among team members and produce better outcomes for patients. Promoting the use of NPPV in any institution may require the development of protocols that include indications, exclusion criteria, management guidelines, and discontinuation criteria. Protocols derived from evidence-based medicine and/or best practices, along with institutional approval, could have an impact on the degree of use for NPPV. Often when faced with new and unknown technology, the question remains: Is there a policy and procedure or a protocol for its application? Being able to answer “yes” to these questions might provide more opportunities for the respiratory therapist to apply NPPV. There are tremendous opportunities for the respiratory therapist to be the champion of NPPV.

At BryanLGH Medical Center in Lincoln, Neb, such an NPPV program exists, supported by pulmonary physicians, emergency department physicians, nurses, and, of course, respiratory therapists. The NPPV protocol developed and utilized by this institution is provided in Figure 2. Davies and Gentile⁷ state, “All clinicians must be educated on the application of NIV and must agree that NIV is an attractive therapeutic option. Once providers are in agreement, the progress toward institutional approval becomes much smoother. Perhaps the most important factor in implementing a successful NIV program is influencing physician practice.” Protocols have contributed greatly by helping to standardize the information, assess appropriateness of therapy, and guide clinicians throughout the application process. Protocols provide guidelines upon which less experienced and/or unfamiliar staff can base their clinical decisions. Despite a protocol’s ability to contribute significantly to the success of an NPPV program, there is no replacement for clinical experience and judgment.

The protocol in Figure 2 (at right), with its additional addendums, provides the clinician with information such as indications/contraindications, recommended settings, monitoring, and the discontinuation criteria for NPPV. The protocol is thorough from start to finish, and its information is drawn from evidence-based medicine as well as clinical experience. Before this protocol was adopted as a practice guideline, a consensus had to be reached with regard to its content among both the medical staff and representatives of the respiratory care staff. This protocol is now used throughout the institution and is a component of the standard-order set used by the hospitalist staff. The recurrent use of this protocol by the hospitalist staff for patients admitted with acute respiratory failure or impending respiratory failure indicates a true commitment to NPPV and trust in its champion, the respiratory therapist.

NPPV for OSA Patients in the Postoperative Setting

Obstructive sleep apnea can be a serious compounding factor in patients who present with acute respiratory failure. In postoperative patients, not only is there a risk for respiratory depression, there is also a degree of anatomical impairment that limits the ability to exchange gases. Obstructive sleep apnea is of particular concern, because, although it is present in approximately 24% of middle-aged males and 9% of middle-aged females, it is undiagnosed in 80% of this population.⁸ Obstructive sleep apnea is associated with increased perioperative morbidity and mortality, and one author states: “It is recommended that patients who use CPAP preoperatively should use CPAP postoperatively as it may reduce the risk of airway obstruction and respiratory depression.”⁹ This need for increased monitoring and awareness of patients entering the surgical suite with OSA has caused institutions to put in place a notification system that alerts appropriate staff to possible complications.⁸ One article presents the development of a respiratory therapist notification system that alerts the therapist to patients presenting in the post anesthesia care unit (PACU). The RT then assesses the patient in the PACU and determines, based on presentation and history, whether a patient needs NPPV. Of the 228 patients for whom NPPV was applied, 51 of those patients had no preoperative sleep study.⁷ This study highlights the impact that undiagnosed OSA can have on the treatment of patients in the postoperative setting, with the application of NPPV to 22% of patients who may have otherwise been transferred to the surgical floor without any intervention. With the use of opioid analgesia and patient-controlled analgesia pumps on the surgical floors, it is imperative that OSA patients be identified prior to surgery and followed up postoperatively in an effort to reduce morbidity and mortality from OSA-related complications.

BryanLGH Medical Center is addressing this problem in the preoperative setting. Prior to surgery, the nurse will ask specific questions that are targeted toward determining if the patient is at risk for OSA. Depending on the patient’s response, a “History of Sleep Apnea” order is generated to alert the respiratory therapist who will then assess this patient further. Presently in development is a more refined protocol that will utilize the “STOP-BANG” questions. This questionnaire is presented in Figure 3 (shown below); and, write the authors of one study in Singapore, which included 348 patients undergoing polysomnography, “STOP-BANG is a clinically useful tool with high sensitivity that can be used to screen patients for moderate and severe OSA. Using cutoffs of 30 for BMI, 40 cm for neck circumference, and 50 years for age simplifies the application of the tool without affecting performance.”¹⁰ If any patient were to answer “yes” to three of the questions, this will generate a “high risk” alert to anesthesia, and a specific order set will be used, instructing the respiratory therapist to assess and manage this patient in the PACU and on the surgical floor. Recognizing that OSA is a serious threat to the health of postoperative patients and a risk to the surgical institution will further the cause for early detection and preventive action against its associated respiratory depression.

NPPV has contributed greatly to the treatment of respiratory failure in many different clinical settings. Its application and success are a tribute to the respiratory therapists who have adapted to its use and who have learned to apply the technology with great skill and confidence. NPPV’s use, however, can still be taken to a higher level, and this can be achieved through training and sharing experiences in the treatment of respiratory failure in all clinical venues.

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Michael Provencher, BS, RRT, is a staff respiratory therapist, BryanLGH West Medical Center, Lincoln, Neb. Paul Nuccio, MS, RRT, FAARC, is director of pulmonary services, Brigham and Women’s Hospital, Boston. For further information, contact [email protected].

References

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2. Penuelas O, Frutos-Vivar F, Esteban A. Noninvasive positive-pressure ventilation in acute respiratory failure. CMAJ. 2007;177:1211-8.
3. Weng C, Yun-Tao Z, Qing-Hua L, et al. Meta-analysis: noninvasive ventilation in acute cardiogenic pulmonary edema. Ann Intern Med. 2010;152:590-600.
4. Gupta D, Nath A, Agarwal R, Behera D. A prospective randomized controlled trial of the efficacy of noninvasive ventilation in severe acute asthma. Respir Care. 2010;55:536-43.
5. Hess D, Pang J, Camargo C. A survey of the use of noninvasive ventilation in academic emergency departments in the United States. Respir Care. 2009;54:1306-12.
6. Chiumello D. Is noninvasive ventilation still underused by physicians? Respir Care. 2009;54:1302-3.
7. Davies J, Gentile M. What does it take to have a successful noninvasive ventilation program? Respir Care. 2009;54:53-61.
8. Ramachandran S, Kheterpal S, Haas C, Cowan A, Tremper KK. Automated notification of suspected obstructive sleep apnea patients to the perioperative respiratory therapist: a pilot study. Respir Care. 2010;55:414-8.
9. Rudra A, Chatterjee S, Das T, Sengupta S, Maltra G, Kumar P. Obstructive sleep apnoea and anaesthesia. Indian J Crit Care Med. 2008;12:116-23.
10. Ong TH, Raudha S, Fook-Chong S, Lew N, Hsu AA. Simplifying STOP-BANG: use of a simple questionnaire to screen for OSA in an Asian population. Sleep Breath. Epub 2010 April 26.