Just as you are able to sit down for the first time in hours in the ED, a colleague walks by and says, “I don’t know what’s going on with your new patient, but she doesn’t look good.” You hurry to find a frail, elderly woman sitting upright, mouth agape. She is tachypneic, with a respiratory rate of 40 breaths/min, and is using accessory respiratory muscles. According to EMS, her pulse oximetry reading improved from 67% on 2-L nasal cannula to 80% on a 15-L nonrebreather mask. She has virtually no breath sounds on lung auscultation except for occasional faint wheezing. You initiate bilevel noninvasive ventilation (NIV), and inline continuous nebulizer treatments are started. The respiratory therapist suggests endotracheal intubation, and you suspect that extubation in the ICU will be difficult, further along the treatment course. As the respiratory therapist sets the bilevel NIV at a PIP 12 over PEEP 5, she asks you, “What parameters would make you decide to proceed with endotracheal intubation?”
Meanwhile, you are alerted to an EMS arrival in the resuscitation bay. They have brought an obese 60-something-year-old man, who was “found down.” Initial evaluation was remarkable for somnolence with arousal to painful stimuli. He has been unable to provide his name or past medical history. His vital signs are remarkable for a respiratory rate of 10 breaths/min and hypoxia with a SpO2 in the mid-80s on room air. He has right lower lung basilar crackles. According to EMS, his hypoxia did not improve on a nonrebreather mask, so CPAP was initiated in the field. Since then, his SpO2 has improved marginally to the high 80s, but he still arouses only to painful stimuli. During your initial assessment, the patient vomits into the NIV mask, aspirates, and his SpO2 plummets when the face mask is removed. As you scramble to assemble RSI and intubation materials, you wonder if CPAP was contraindicated and if this airway catastrophe could have been prevented.
Mulling over your stressful patient load, you walk to the bedside of a 9-year-old girl with a past medical history of cerebral palsy. Although she is only minimally interactive, she is accompanied by her attentive parents who are deeply involved with her medical care. Her mother looks worried and explains that her daughter “isn’t breathing right” and that she feels warm. The father mentions a history of a worsening cough. On chart review, you note that her restrictive lung disease from underlying cerebral palsy is worsening, and that she now requires BPAP at night. On examination, you see a mentally and developmentally delayed girl with subcostal retractions, tachycardia to 125 beats/min, tachypnea to 35 breaths/min, and an oral temperature of 38.3°C (101°F), but she is maintaining an oxygen saturation of 97% on room air. A chest x-ray confirms a right upper lobar pneumonia. The patient shows increased work of breathing, and you wonder if NIV would help.
Acute respiratory failure is an emergency that requires a management strategy tailored to the individual patient and to the resources available. Endotracheal intubation is definitive airway management, but it can have complications. In addition, rapid sequence intubation (RSI) requires a degree of preparation and time that might not be available in the acutely distressed patient. For example, important equipment needs assembly, often the clinical environment is not optimal (such as with refractory hypoxia or abnormal anatomy that makes RSI riskier), or the patient has an underlying condition that could lead to further complication as a result of paralysis (such as in acidosis). Ultimately, with RSI there is a level of risk to the patient, both during the initial procedure of induction, sedation, laryngoscopy, and tube delivery, as well as post procedure, with ventilator-associated risks such as pulmonary barotrauma or ventilator-associated pneumonia.
In consideration of risks associated with definitive airway management, noninvasive strategies that include continuous positive airway pressure (CPAP) and bilevel positive airway pressure (BPAP) are viable management options. These techniques provide a “fast-on” intervention that provides more respiratory support than nasal cannula or a conventional face mask. Unlike endotracheal intubation, NIV is not definitive airway management, and the patient must be closely monitored for signs of clinical deterioration. Nonetheless, NIV can improve the patient’s condition sufficiently to either reverse the underlying acute illness or, alternatively, it may serve to safely delay intubation until proper setup is available.1 In the case of patients who have a “do not intubate” (DNI) directive, NIV may also allow for temporary life-sustaining support while a potentially reversible process is addressed.2
NIV was introduced for management of acute respiratory failure in the 1940s, but became a mainstay of respiratory management only in the last 20 years. A multicenter database review over a 15-year study period from 1997 to 2011 showed that first-line NIV use increased from 29% to 42%, and the success rate improved from 69% to 84%.3 Success was defined as not requiring use of mechanical ventilation and increased patient survival.
A comprehensive understanding of the physiologic benefits of NIV can lead to efficient and clinically appropriate management decisions. As there was an excellent review article by Torres and Radeos published in a 2011 issue of EM Critical Care,4 this review is designed to provide an update of the literature since then, and to offer evolving perspectives on the increasing utilization of NIV in the setting of acute respiratory distress.
Searches were conducted through PubMed and OVID Medline® for literature from 2010 to 2016. Keywords included noninvasive ventilation, with and without the qualifying inclusion of the term acute respiratory failure, to limit the resources to acute conditions. The search was restricted to studies available in the English language. The references from the articles identified were then searched for additional references, retrieving more than 700 articles. Priority was given to articles addressing commonly occurring emergent medical conditions, with additional special attention given to topics falling under the category of emerging areas of research.
Evidence-based medicine requires a critical appraisal of the literature based upon study methodology and number of subjects. Not all references are equally robust. The findings of a large, prospective, randomized, and blinded trial should carry more weight than a case report.
To help the reader judge the strength of each reference, pertinent information about the study is included in bold type following the reference, where available. The most informative references cited in this paper, as determined by the authors, are noted by an asterisk (*) next to the number of the reference.
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Nikita Joshi, MD; Molly K. Estes, MD; Kayla Shipley, MD; Hyun-Chul Danny Lee, MD
February 1, 2017
February 29, 2020
Upon competion of this article, you should be able to:
Physician CME Information
Date of Original Release: February 1, 2017. Date of most recent review: January 10, 2017. Termination date: February 1, 2020.
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