Noninvasive Ventilation in Acute Respiratory Failure

Nicholas S. Hill, MD; John Brennan, MD; Erik Garpestad, MD; Stefano Nava, MD

Crit Care Med.  2007;35(10):2402-2407.  ©2007 Lippincott Williams & Wilkins
Posted 11/13/2007

Abstract and Introduction

Abstract

Background: Noninvasive ventilation has assumed an important role in the management of respiratory failure in critical care units, but it must be used selectively depending on the patient's diagnosis and clinical characteristics.
Data: We review the strong evidence supporting the use of noninvasive ventilation for acute respiratory failure to prevent intubation in patients with chronic obstructive pulmonary disease exacerbations or acute cardiogenic pulmonary edema, and in immunocompromised patients, as well as to facilitate extubation in patients with chronic obstructive pulmonary disease who require initial intubation. Weaker evidence supports consideration of noninvasive ventilation for chronic obstructive pulmonary disease patients with postoperative or postextubation respiratory failure; patients with acute respiratory failure due to asthma exacerbations, pneumonia, acute lung injury, or acute respiratory distress syndrome; during bronchoscopy; or as a means of preoxygenation before intubation in critically ill patients with severe hypoxemia.
Conclusion: Noninvasive ventilation has assumed an important role in managing patients with acute respiratory failure. Patients should be monitored closely for signs of noninvasive ventilation failure and promptly intubated before a crisis develops. The application of noninvasive ventilation by a trained and experienced intensive care unit team, with careful patient selection, should optimize patient outcomes.

Introduction

Noninvasive ventilation (NIV), a form of ventilatory support that avoids airway invasion, has seen increasing use in emergency departments and intensive care units (ICUs) in recent years, based on the results of clinical trials showing improved outcomes in certain types of acute respiratory failure (ARF).[1] NIV usually refers to the provision of inspiratory pressure support plus positive end-expiratory pressure (PEEP) via a nasal or face mask. Although continuous positive airway pressure (CPAP) does not actively assist inspiration and is not a ventilatory support mode, it is considered a form of NIV here when used as a therapy for ARF. The successful application of NIV requires the training and collaboration of an experienced ICU team, including intensivists, nurses, and respiratory therapists.[2] This review will focus on the evidence supporting the use of NIV in various forms of respiratory failure ( Table 1 ), selection of appropriate patients, and techniques for successful implementation.

NIV for Specific Types of Acute Respiratory Failure: Evidence and Recommendations

Hypercapnic Respiratory Failure

Chronic Obstructive Pulmonary Disease. NIV should be considered first-line therapy in the management of ARF caused by chronic obstructive pulmonary disease (COPD) exacerbations based on evidence derived from multiple randomized trials.[2-5] Meta-analyses by Dr. Lightowler and colleagues[6] and Dr. Keenan and colleagues[7] show reduced intubation rates, hospital lengths of stay, and mortality with NIV use. The strength of the evidence justifies the application of NIV as a standard of care in appropriately selected patients with hypercapnic ARF due to COPD. Although considered a contraindication to NIV in the past, hypercapnic coma in patients with COPD can be treated with NIV as successfully as in noncomatose patients.[8,9]

The use of NIV as an alternative to endotracheal intubation in more severely ill patients (i.e., those with a pH < 7.2) has been controversial. However, recent studies demonstrate that outcomes of severe COPD exacerbations are no worse if treated with NIV than with endotracheal intubation,[10,11] indicating that an initial trial with NIV is not deleterious, even in severely ill COPD patients.

Asthma. Evidence is weaker for the use of NIV in asthma patients with acute respiratory failure. An uncontrolled study[12] observed improved gas exchange and avoidance of intubation in 15 of 17 patients with status asthmaticus, and all patients survived. A subsequent randomized pilot study in 33 patients with acute asthma but not ARF showed improved flow rates and decreased hospitalizations with NIV vs. sham NIV.[13] However, Dr. Ram and colleagues[14] concluded that large randomized controlled trials (RCTs) are needed before recommending NIV use in status asthmaticus. A trial of NIV can be considered in asthmatics who fail to respond adequately to initial bronchodilator therapy to improve air flow obstruction and decrease the work of breathing. Patients should be monitored closely and intubated promptly if there is no improvement in the first hour or two, because these patients can deteriorate rapidly.

Facilitating Extubation in COPD. Filitation of extubation in patients with ARF due to COPD exacerbations is another application of NIV supported by strong evidence. In intubated patients with COPD and hypercapnic respiratory failure who failed a single[15] or repeated T-piece trials[16] and were extubated to NIV or continued on invasive ventilation and weaned according to a standard pressure support protocol, randomized trials showed an increased weaning rate at 28 days, decreased durations of mechanical ventilation and ICU stay, and reduced rates of nosocomial pneumonia and 60-day mortality. Based on these findings, patients intubated for hypercapnic respiratory failure due to COPD who fail spontaneous breathing trials should be considered for a trial of extubation to NIV. This approach should be reserved for patients who are good candidates for NIV in other respects and who are able to tolerate levels of pressure support easily administered via mask (i.e., ≤ 15 cm H2O). In addition, they should not have been a difficult intubation.

Hypoxemic Respiratory Failure

Hypoxemic ARF is defined by a Pao2/Fio2 ratio < 200 and a variety of different non-COPD etiologies. It is a very broad category, and studies focusing on it are difficult to apply to individual patients. The concern is that responses within an etiologic subcategory-harmful or beneficial-could be obscured by responses in other subcategories. Therefore, the following will consider studies focusing on the subcategories.

Cardiogenic Pulmonary Edema. The use of NIV or CPAP in patients with cardiogenic pulmonary edema is supported by multiple randomized trials.[17-23] The main physiologic benefit from NIV or CPAP in these patients is likely due to an increase in functional residual capacity that reopens collapsed alveoli and improves oxygenation. This also increases lung compliance and reduces work of breathing. The increased intrathoracic pressure also can improve cardiac performance by decreasing ventricular preload and afterload.

Several meta-analyses have shown equivalent reductions in intubation and mortality rates with CPAP and NIV for cardiogenic pulmonary edema, although the reduction in mortality with NIV was not statistically significant in some, probably because there were fewer NIV than CPAP studies.[24,25] However, several studies have shown more rapid reductions in respiratory rate and dyspnea with NIV than with CPAP alone.[20,26] Thus, either NIV or CPAP can be used to treat cardiogenic pulmonary edema with equal expectations of success. Some recommend starting with CPAP, because it is a simpler and potentially less expensive therapy, with pressure support added if patients remain dyspneic or hypercapnic on CPAP alone.

Pneumonia. Pneumonia has been a challenge to treat noninvasively and has been identified as a risk factor for NIV failure.[27] Two thirds of patients with severe community-acquired pneumonia required intubation after being started on NIV in one cohort study, even though those who succeeded with NIV had very good outcomes.[28] An RCT on patients with severe community-acquired pneumonia showed that NIV reduced intubation rates, ICU length of stay, and 2-month mortality rate, but only in the subgroup with underlying COPD.[29] Another RCT on patients with hypoxemic respiratory failure[30] showed that NIV reduced the need for intubation among patients with pneumonia (26% vs. 73% in the conventional therapy group), but a more recent RCT[31] testing NIV as an alternative to invasive ventilation in patients with various types of ARF found that the subgroup with pneumonia did very poorly, with all eight patients randomized to NIV requiring intubation. The scant and conflicting data do not support the routine use of NIV in patients with severe pneumonia, with the exception of patients with underlying COPD. However, a cautious trial of NIV may be considered in patients with pneumonia deemed to be excellent candidates, but they need careful monitoring, because the risk of failure is high.

Acute Lung Injury/Acute Respiratory Distress Syndrome. Studies on NIV to treat acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) have reported failure rates ranging from 50% to > 80%,[27,30,32,33] but no RCTs have focused on ALI/ARDS exclusively. Independent risk factors for NIV failure in this group of patients include severe hypoxemia, shock, and metabolic acidosis.[33] A recent prospective multicenter survey found that when NIV was used as first-line therapy for selected ALI/ARDS patients (those with > 2 organ failures, hemodynamic instability, or encephalopathy were excluded), 54% avoided intubation and had excellent outcomes.[34] Predictors of NIV failure were Simplified Acute Physiology Score II > 34 and Pao2/Fio2 ≤ 175 after the first hour of therapy. Thus, although NIV cannot be recommended as routine therapy for ALI/ARDS, these data support a cautious trial in highly selected patients with a Simplified Acute Physiology Score II ≤ 34 and readiness to promptly intubate if oxygenation fails to improve sufficiently within the first hour.

Respiratory Failure in Immunocompromised Patients. RCTs in recipients of solid-organ or bone-marrow transplants who developed hypoxemic respiratory failure have found decreased intubation and ICU mortality rates and shorter ICU lengths of stay in patients treated with NIV as compared with conventional therapy.[35,36] Similar findings have been reported for acquired immune deficiency syndrome patients in a nonrandomized study.[37] The reduced mortality is likely related to reduced infectious complications associated with NIV use compared with endotracheal intubation, including ventilator-associated pneumonia, other nosocomial infections, and septic shock.[38] These data support NIV as the preferred initial ventilatory modality for these patients, to avoid intubation and its associated risks.

Postoperative Respiratory Failure

Both CPAP and NIV have shown benefit in the postoperative period. When used prophylactically after major abdominal surgery[39] or thoracoabdominal aneurysm repair,[40] CPAP (10 cm H2O) reduces the incidence of hypoxemia, pneumonia, atelectasis, and intubations compared with standard treatment. In the only RCT of NIV in the postoperative setting, patients with hypoxemic respiratory failure after lung resection had reduced intubation and mortality rates if treated with NIV when compared with standard management.[41] Because these studies have examined different techniques following various surgeries, firm specific recommendations cannot be made. However, the data lend support to the use of CPAP or NIV in postoperative patients, either prophylactically in high-risk patients or as an early therapy of respiratory insufficiency.

Postextubation Respiratory Failure

Extubation failure is associated with high morbidity and mortality, and NIV has been suggested as a way to avoid re-intubation and improve outcomes. An earlier RCT found no reduction in reintubations among patients who developed respiratory distress within 48 hrs of extubation, although few patients with COPD were included in this study and the level of pressure support used may have been subtherapeutic.[42] Another RCT attempted to prevent extubation failure by starting NIV (or continuing standard therapy) as soon as patients developed signs of extubation failure.[43] Surprisingly, not only did NIV fail to reduce reintubations, but its use also was associated with increased ICU mortality, thought to be related to delays in needed reintubation. Only 10% of patients in this trial had COPD, however. Two subsequent RCTs[44,45] on patients deemed to be at high risk for extubation failure found that NIV reduced the need for reintubation and ICU mortality, but in one of the studies the hypercapnic subgroup (mainly COPD patients) had most of the benefit.[45] These data support the use of NIV in patients at high risk of extubation failure, particularly if they have COPD, congestive heart failure, and/or hypercapnia. However, early indiscriminate use in all patients with risk factors is discouraged. Patients with extubation failure treated with NIV should be monitored closely and delays in needed intubation avoided.

Palliative Care and Do-Not-Intubate Status

A prospective cohort series[46] evaluated 114 patients with acute respiratory failure and a status of do not intubate. Overall, 43% of the patients survived the hospitalization, and those with diagnoses of cardiogenic pulmonary edema and COPD had hospital survival rates > 50%. The presence of a cough and an awake mental status imparted a favorable prognosis. Another prospective cohort series also showed favorable success rates in do not intubate patients with COPD and cardiogenic pulmonary edema, but a high failure rate in patients with hypoxemic respiratory failure, postextubation failure, and end-stage cancer.[47] Depending on patient and/or family wishes, a trial of NIV can be considered in do-not-intubate patients, but the goals of therapy should be clear.[48] If the patient and/or family desire prolonged survival, then use should be reserved primarily for COPD and congestive heart failure patients. On the other hand, if the goal is to palliate, to relieve dyspnea, or to delay death so that affairs can be settled, then NIV can be used for these as well as other diagnoses. However, it should be reassessed frequently and stopped if the goal of palliation is not being met.

Other ICU Applications of NIV

Preoxygenation Before Intubation. Critically ill patients with hypoxic respiratory failure are at high risk of oxygen desaturations during intubation. A recent RCT of such patients[49] showed that preoxygenation with NIV before intubation resulted in improved oxygen saturation during and after intubation and decreased the incidence of oxygen desaturations below 80% during intubation. This approach is promising but should be further studied before routine use can be recommended.

Fiberoptic Bronchoscopy. A RCT has shown that CPAP alone (up to 7.5 cm H2O) improves oxygenation and reduces postprocedure respiratory failure in patients with severe hypoxemia undergoing bronchoscopy.[50] In an RCT[51] of 26 patients with hypoxemia (Pao2/Fio2 ratio < 200), NIV increased Pao2/Fio2 by 82% compared with a 10% worsening in the conventional oxygen therapy group. Successful bronchoscopy during NIV also has been reported in hypercapnic COPD patients with pneumonia. NIV improved oxygen saturation, and all 10 patients tolerated the procedure without complications.[52] The evidence supports the use of NIV during fiberoptic bronchoscopy, especially when risks of intubation are deemed high, such as in immunocompromised patients or in those with bleeding diatheses. However, the ICU team must be prepared for the possibility of emergent intubation.

Patient Selection

Selection of appropriate patients is an important skill that is key to the successful application of NIV. In brief, it is a clinical judgment that takes into consideration the etiology of the ARF and evidence for efficacy ( Table 1 ). Good candidates for NIV have a demonstrable need for ventilatory assistance and no contraindications to NIV ( Table 2 ). In addition, consideration of predictors of success and failure may be helpful ( Table 3 ); intubation is preferred if the likelihood of failure is too great. Numerous studies have demonstrated that the response to NIV after the first hour or two is the best predictor of eventual outcome.[27,34,53] Therefore, when in doubt, a brief, cautious trial of NIV can be attempted, with plans to intubate if the patient fails to improve sufficiently.

NIV Techniques

Although technical aspects such as choice of interface and ventilator settings are clearly important to NIV success, the human factor is important, as well. As caregivers in one ICU gained experience with NIV, success rates remained stable even as more severely ill patients were treated.[54]

Selection of an Interface. Selection of a properly fit and comfortable interface is critical to NIV success. Although patients rate nasal masks as more comfortable than full face masks,[55] an RCT demonstrated that full face masks are better tolerated than nasal masks for ARF because of less air leaking through the mouth.[56]

Selection of a Ventilator and Ventilator Settings. Either critical care or bilevel positive-pressure ventilators can be used to administer NIV to ARF patients; no study has demonstrated superiority of one type over the other. Although many critical care ventilators now offer NIV modes that provide pressure support ventilation with leak compensation and silencing of nuisance alarms, little data are available to demonstrate clinical efficacy. The determination of optimal ventilator settings also has been inadequately studied, but is usually a process of balancing the ability to reduce work of breathing by providing an adequate level of pressure support (usually > 8-10 cm H2O) against the discomfort and greater air leaking imposed by higher pressures. A common mistake is to start with a low inspiratory pressure to facilitate tolerance and then to fail to titrate pressures upward to reduce respiratory effort.

In COPD, the inspiratory threshold load imposed by intrinsic PEEP is a major component of the work of breathing. External PEEP, usually not higher than 5 cm H2O to 7 cm H2O, should be provided with pressure support to these patients to minimize inspiratory effort.[57]

In a study designed to determine optimal NIV settings in patients with ALI, a PEEP of 10 cm H2O improved Pao2/Fio2 more than a PEEP of 5 cm H2O.[58] A pressure support of 15 cm H2O and a PEEP of 5 cm H2O decreased Paco2, respiratory rate, and work of breathing, and improved dyspnea more than a pressure support of 10 cm H2O and PEEP of 10 cm H2O, even though Pao2/Fio2 was better with the higher PEEP. This study shows that adjusting settings may require a balancing of beneficial and adverse effects to come up with the best combination for a given patient.

Monitoring of NIV. To assure the success of NIV, close monitoring is necessary, especially during the initiation period ( Table 4 ). Favorable subjective responses-including tolerance of the mask and air pressure and reduction of respiratory distress and effort-are important to establish early. Air leaking should be sought and minimized, and gas exchange should be stabilized and improved.

The location of NIV delivery also is important to assure adequate monitoring. Most studies have monitored patients in ICUs or respiratory step-down units, but some have reported successful application of NIV on general medical wards.[59,60] Monitoring should be tailored to the acuity of illness. If the patient becomes unstable within minutes of mask removal, then close monitoring is mandatory, ideally in an ICU or respiratory unit.

Conclusion

Strong evidence from randomized trials supports the use of NIV in the management of ARF to prevent endotracheal intubation in patients with COPD exacerbations or acute cardiogenic pulmonary edema, and in immunocompromised patients, as well as to facilitate extubation in patients with COPD. NIV should be contemplated in patients with postoperative respiratory failure or at high risk for postextubation respiratory failure who are otherwise good candidates for NIV, and as a means of preoxygenating critically ill patients with hypoxemia before intubation. NIV can be considered in patients with asthma exacerbations, pneumonia, and ALI/ARDS, although the supporting evidence is fairly weak; these and other acutely ill patients should be monitored closely for signs of NIV failure until stabilized. If there are signs of NIV failure, patients should be intubated promptly before a crisis develops. The application of NIV by a trained and experienced ICU team, with careful patient selection, should optimize patient outcomes.


Table 1. Noninvasive Ventilation for Various Types of Acute Respiratory Failure (ARF): Evidence for Efficacy and Strength of Recommendation


Table 1: Noninvasive Ventilation for Various Types of Acute Respiratory Failure (ARF): Evidence for Efficacy and Strength of Recommendation


    Table 2. General Guidelines for Selection of Patients for Noninvasive Ventilation


    Table 2: General Guidelines for Selection of Patients for Noninvasive Ventilation


      Table 3. Predictors of Failure: Noninvasive Ventilation (NIV) for Acute Respiratory Failure


      Table 3: Predictors of Failure: Noninvasive Ventilation (NIV) for Acute Respiratory Failure


        Table 4. Monitoring of Noninvasive Ventilation for Acute Respiratory Failure


        Table 4: Monitoring of Noninvasive Ventilation for Acute Respiratory Failure




          References

          1. Mehta S, Hill NS: Noninvasive ventilation: State of the art. Am J Respir Crit Care Med 2001; 163:540-577
          2. Brochard L, Isabey D, Piquet J, et al: Reversal of acute exacerbations of chronic obstructive lung disease by inspiratory assistance with a face mask. N Engl J Med 1990; 323:1523-1530
          3. Bott J, Carroll MP, Conway JH, et al: Randomised controlled trial of nasal ventilation in acute ventilatory failure due to chronic obstructive airways disease. Lancet 1993; 341:1555-1557
          4. Kramer N, Meyer TJ, Meharg J, et al: Randomized, prospective trial of noninvasive positive pressure ventilation in acute respiratory failure. Am J Respir Crit Care Med 1995; 151:1799-1806
          5. Plant PK, Owen JL, Elliott MW: Early use of non-invasive ventilation for acute exacerbations of chronic obstructive pulmonary disease on general respiratory wards: A multicentre randomised controlled trial. Lancet 2000; 355:1931-1935
          6. Lightowler J, Wedjicha JA, Elliott MW, et al: Non-invasive positive pressure ventilation to treat respiratory failure resulting from exacerbations of chronic obstructive pulmonary disease: Cochrane systematic review and meta-analysis. BMJ 2003; 326:185-187
          7. Keenan SP, Sinuff T, Cook DJ, et al: Which patients with acute exacerbation of chronic obstructive pulmonary disease benefit from noninvasive positive pressure ventilation? A systematic review of the literature. Ann Intern Med 2003; 138:861-870
          8. Gonzalez Diaz G, Carillo A, Perez P, et al: Noninvasive positive-pressure ventilation to treat hypercapnic coma secondary to respiratory failure. Chest 2005; 127:952-960
          9. Scala R, Naldi M, Archinucci I, et al: Noninvasive positive-pressure ventilation in patients with acute exacerbations of COPD and varying levels of consciousness. Chest 2005; 128:1657-1666
          10. Conti G, Antonelli M, Navalesi P, et al: Noninvasive vs. conventional mechanical ventilation in patients with chronic obstructive pulmonary disease after failure of medical treatment in the ward: A randomized trial. Intensive Care Med 2002; 28:1701-1707
          11. Squadrone E, Frigerio P, Fogliati C, et al: Noninvasive vs. invasive ventilation in COPD patients with severe acute respiratory failure deemed to require ventilatory assistance. Intensive Care Med 2004; 30:1303-1310
          12. Meduri GU, Cook TR, Turner RE, et al: Noninvasive positive pressure ventilation in status asthmaticus. Chest 1996; 110:767-774
          13. Soroksky A, Stav D, Shpirer I: A pilot prospective, randomized, placebo-controlled trial of bi-level positive airway pressure in acute asthmatic attack. Chest 2003; 123:1018-1025
          14. Ram FS, Wellington S, Rowe B, et al: Non-invasive positive pressure ventilation for treatment of respiratory failure due to severe acute exacerbations of asthma. Cochrane Database Syst Rev 2005; 1:CD004360
          15. Nava S, Ambrosino N, Clini E, et al: Non-invasive mechanical ventilation in the weaning of patients with respiratory failure due to chronic obstructive pulmonary disease: A randomized study. Ann Intern Med 1998; 128:721-728
          16. Ferrer M, Esquinas A, Arancibia F, et al: Noninvasive ventilation during persistent weaning failure. A randomized controlled trial. Am J Respir Crit Care Med 2003; 168:70-76
          17. Bersten AD, Holt AW, Vedig AE, et al: Treatment of severe cardiogenic pulmonary edema with continuous positive airway pressure delivered by face mask. N Engl J Med 1991; 325:1825-1830
          18. Lin M, Yang Y, Chiany H, et al: Reappraisal of continuous positive airway pressure therapy in acute cardiogenic pulmonary edema: Short-term results and long-term follow-up. Chest 1995; 107:1379-1386
          19. Nava S, Carbone G, DiBattista N, et al: Noninvasive ventilation in cardiogenic pulmonary edema: A multicenter randomized trial. Am J Respir Crit Care Med 2003; 168:1432-1437
          20. Crane SD, Elliott MW, Gilligan P, et al: Randomised controlled comparison of continuous positive airways pressure, bilevel non-invasive ventilation, and standard treatment in emergency department patients with acute cardiogenic pulmonary oedema. Emerg Med J 2004; 21:155-161
          21. Pang D, Keenan SP, Cook DJ, et al: The effect of positive airway pressure on mortality and the need for intubation in cardiogenic pulmonary edema. Chest 1998; 114:1185-1192
          22. Rasanen J, Heikkila J, Downs J, et al: Continuous positive airway pressure by face mask in acute cardiogenic pulmonary edema. Am J Cardiol 1985; 55:296-300
          23. Lin M, Chiang HT: The efficacy of early continuous positive airway pressure therapy in patients with acute cardiogenic pulmonary edema. J Formos Med Assoc 1991; 90:736-743
          24. Masip J, Roque M, Sanchez B, et al: Noninvasive ventilation in acute cardiogenic pulmonary edema. JAMA 2005; 294:3124-3130
          25. Winck JC, Azevedo LF, Costa-Pereira A, et al: Efficacy and safety of non-invasive ventilation in the treatment of acute cardiogenic pulmonary edema-a systematic review and meta-analysis. Crit Care 2006; 10:R69
          26. Mehta S, Jay GD, Woolard RH, et al: Randomized, prospective trial of bilevel versus continuous positive airway pressure in acute pulmonary edema. Crit Care Med 1997; 25:620-628
          27. Antonelli M, Conti G, Moro ML, et al: Predictors of failures of noninvasive positive pressure ventilation in patients with acute hypoxemic respiratory failure: A multi-center study. Intensive Care Med 2001; 27:1718-1728
          28. Jolliet P, Abajo B, Pasquina P, et al: Non-invasive pressure support ventilation in severe community-acquired pneumonia. Intensive Care Med 2001; 27:812-821
          29. Confalonieri M, Potena A, Carbone G, et al: Acute respiratory failure in patients with severe community-acquired pneumonia. A prospective randomized evaluation of noninvasive ventilation. Am J Respir Crit Care Med 1999; 160:1585-1591
          30. Ferrer M, Esquinas A, Leon M, et al: Noninvasive ventilation in severe hypoxemic respiratory failure. A randomized clinical trial. Am J Respir Crit Care Med 2003; 168:1438-1444
          31. Honrubia T, Garcia Lopez FJ, Franco N, et al: Noninvasive vs. conventional mechanical ventilation for acute respiratory failure. Chest 2005; 128:3916-3924
          32. Rocker GM, Mackensie MG, Williams B, et al: Noninvasive positive pressure ventilation. Successful outcome in patients with acute lung injury/ARDS. Chest 1999; 115:173-177
          33. Rana S, Hussam J, Gay P, et al: Failure of non-invasive ventilation in patients with acute lung injury: Observational cohort study. Crit Care 2006; 10:R79
          34. Antonelli M, Conti G, Esquinas A, et al: A multiple-center survey on the use in clinical practice of noninvasive ventilation as a first-line intervention for acute respiratory distress syndrome. Crit Care Med 2007; 35:18-25
          35. Antonelli M, Conti G, Bufi M, et al: Noninvasive ventilation for treatment of acute respiratory failure in patients undergoing solid organ transplantation: A randomized trial. JAMA 2000; 283:235-241
          36. Hilbert G, Gruson D, Vargas F, et al: Noninvasive ventilation in immunosuppressed patients with pulmonary infiltrates and acute respiratory failure. N Engl J Med 2001; 344:481-487
          37. Confalonieri M, Calderini E, Terraciano S, et al: Noninvasive ventilation for treating acute respiratory failure in AIDS patients with Pneumocystis carinii pneumonia. Intensive Care Med 2002; 28:1233-1238
          38. Nourdine K, Combes P, Carton MJ, et al: Does noninvasive ventilation reduce the ICU nosocomial infection risk? A prospective clinical survey. Intensive Care Med 1999; 25:567-573
          39. Squadrone V, Coha M, Cerutti E, et al: Continuous positive airway pressure for treatment of postoperative hypoxemia: A randomized controlled trial. JAMA 2005; 293:589-595
          40. Kindgen-Milles D, Müller E, Buhl R, et al: Nasal continuous positive airway pressure reduces pulmonary morbidity and length of stay following thoracoabdominal aortic surgery. Chest 2005; 128:821-828
          41. Auriant I, Jallot A, Herve P, et al: Noninvasive ventilation reduces mortality in acute respiratory failure following lung resection. Am J Respir Crit Care Med 2001; 164:1231-1235
          42. Keenan SP, Powers C, McCormack DG, et al: Noninvasive positive-pressure ventilation for postextubation respiratory distress: A randomized controlled trial. JAMA 2002; 287:3238-3244
          43. Esteban A, Frutos-Vivar F, Ferguson ND, et al: Noninvasive positive-pressure ventilation for respiratory failure after extubation. N Engl J Med 2004; 350:2452-2460
          44. Nava S, Gregoretti C, Fanfulla F, et al: Noninvasive ventilation to prevent respiratory failure after extubation in high-risk patients. Crit Care Med 2005; 33:2465-2470
          45. Ferrer M, Valencia M, Nicolas JM, et al: Early noninvasive ventilation averts extubation failure in patients at high risk: A randomized trial. Am J Respir Crit Care Med 2006; 173:164-170
          46. Levy MM, Tanios MA, Nelson D, et al: Outcomes of patients with do-not-intubate orders treated with noninvasive ventilation. Crit Care Med 2004; 32:2002-2007
          47. Schettino G, Altobelli N, Kacmarek RM: Noninvasive positive-pressure ventilation reverses acute respiratory failure in select do-not-intubate patients. Crit Care Med 2005; 33:1976-1982
          48. Curtis RJ, Cook DJ, Sinuff T, et al: Noninvasive positive pressure ventilation in critical and palliative care settings: Understanding the goals of therapy. Crit Care Med 2007; 35:932-939
          49. Baillard C, Fosse JP, Sebbane M, et al: Noninvasive ventilation improves preoxygenation before intubation in hypoxic patients. Am J Respir Crit Care Med 2006; 174:171-177
          50. Maitre B, Jaber S, Maggiore SM, et al: Continuous positive airway pressure during fiberoptic bronchoscopy in hypoxemic patients. A randomized double-blind study using a new device. Am J Respir Crit Care Med 2000; 162:1063-1067
          51. Antonelli M, Conti G, Rocco M, et al: Noninvasive positive-pressure ventilation vs. conventional oxygen supplementation in hypoxemic patients undergoing diagnostic bronchoscopy. Chest 2002; 121:1149-1154
          52. Da Conceicao M, Genco G, Favier JC, et al: Fiberoptic bronchoscopy during noninvasive positive-pressure ventilation in patients with chronic obstructive lung disease with hypoxemia and hypercapnea. Ann Fr Anesth Reanim 2000; 19:231-236
          53. Confalonieri M, Garuti G, Cattaruzza MS, et al: Italian noninvasive positive pressure ventilation (NPPV) study group. A chart of failure risk for noninvasive ventilation in patients with COPD exacerbation. Eur Respir J 2005; 25:348-355
          54. Carlucci A, Delmastro M, Rubini F, et al: Changes in the practice of non-invasive ventilation in treating COPD patients over 8 years. Intensive Care Med 2003; 29:419-425
          55. Navalesi P, Fanfulla F, Frigerio P, et al: Physiologic evaluation of noninvasive mechanical ventilation delivered with three types of masks in patients with chronic hypercapnic respiratory failure. Crit Care Med 2000; 28:1785-1790
          56. Kwok H, McCormack J, Cece R, et al: Controlled trial of oronasal versus nasal mask ventilation in the treatment of acute respiratory failure. Crit Care Med 2003; 31:468-473
          57. Appendini L, Patessio A, Zanaboni S, et al: Physiologic effects of positive end-expiratory pressure and mask pressure support during exacerbations of chronic obstructive pulmonary disease. Am J Respir Crit Care Med 1994; 149:1069-1076
          58. L'Her E, Deye N, Lellouche F, et al: Physiologic effects of noninvasive ventilation during acute lung injury. Am J Respir Crit Care Med 2005; 172:1112-1118
          59. Plant PK, Owen JL, Elliot, MW: Early use of non-invasive ventilation for acute exacerbations of chronic obstructive pulmonary disease on general respiratory wards: A multi-centre randomised controlled trial. Lancet 2000; 1931-1935
          60. Farha S, Ghamra ZW, Hoisington ER, et al: Use of noninvasive positive-pressure ventilation on the regular hospital ward: Experience and correlates of success. Respir Care 2006; 51:1237-1243
          Reprint Address

          For information regarding this article, E-mail: nhill@tufts-nemc.org


          Nicholas S. Hill, MD,1 John Brennan, MD,1 Erik Garpestad, MD,1 and Stefano Nava, MD2

          1The Division of Pulmonary, Critical Care, and Sleep Medicine, Tufts-New England Medical Center, Boston, MA
          2The Respiratory Intensive Care Unit, Fondazione Salvatore Maugeri, Istituto di Ricovero e Cura a Carattere Scientifico, Istituto Scientifico di Pavia, Pavia, Italy

          Disclosure: Consultant fees and research grants received from ResMed (NSH) and Respironics (NSH, SN)