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Noninvasive positive-pressure ventilation reduced the need for intubation in acute respiratory failure

ACP J Club. 1995 Nov-Dec;123:64. doi:10.7326/ACPJC-1995-123-3-064

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Source Citation

Kramer N, Meyer TJ, Meharg J, Cece RD, Hill NS. Randomized, prospective trial of noninvasive positive pressure ventilation in acute respiratory failure. Am J Respir Crit Care Med. 1995 Jun;151:1799-806.



To determine whether noninvasive positive-pressure ventilation (NIPPV) added to standard therapy reduces the need for intubation in patients with acute respiratory failure.


Randomized controlled trial with follow-up until hospital discharge.


2 U.S. teaching hospitals.


31 patients (mean age 69 y, 58% men) with acute respiratory failure. Exclusion criteria were respiratory arrest; hypotension; arrhythmias; upper airway obstruction or facial trauma; or inability to clear secretions, cooperate, or wear a mask. Follow-up was complete.


All patients received standard medical care, which included oxygen to maintain saturation ≥ 90%. 16 patients were allocated to NIPPV (nasal mask with patient flow-triggered ventilatory assist; backup rate, 12 breaths/min). The inspiratory positive airway pressure was initiated at 8 cm H2O and was increased as tolerated. NIPPV was continued for ≥ 8 h/d. Weaning was attempted after 6 hours. 15 patients received standard care only.

Main outcome measures

The primary outcome was need for intubation. Secondary outcomes were heart rate, respiratory function, staff time, length of hospital stay, and costs for hospitalization and respiratory services.

Main results

5 patients (31%) in the NIPPV group needed intubation compared with 11 patients (73%) receiving usual care (P = 0.03) (Table). Respiratory and heart rates were lower in patients in the NIPPV group than in patients in the control group at 1 hour only. No difference was seen between groups for most ventilatory measures at 3 to 6 hours, 12 hours, and 24 hours; nursing or respiratory therapy time; perceived difficulty of treating patients; duration of ventilation; length of hospital stay; hospital and respiratory costs; and mortality.


Noninvasive positive-pressure ventilation added to usual care reduced the need for intubation in patients with acute respiratory failure. Noninvasive positive-pressure ventilation did not increase costs, staff time, mortality, or length of hospital stay.

Source of funding: In part, Respironics, Inc.

For article reprint: Dr. N.S. Hill, Pulmonary and Critical Care Medicine, Rhode Island Hospital, 593 Eddy Street, Providence, RI 02903, USA. FAX 401-444-5493.

Table. Noninvasive positive pressure ventilation (NIPPV) vs standard care for patients with acute respiratory failure*

Outcome at hospital discharge NIPPV Standard care RRR (95% CI) NNT (CI)
Need for intubation 31% 73% 57% (13 to 81) 2 (1 to 14)

*Abbreviations defined in Glossary; RRR, NNT, and CI calculated from data in article.


Enthusiasm for NIPPV has increased since the development of easy-to-fit nasal masks and an inexpensive, reliable, flow-triggered device that provides pressure-support ventilation with a backup respiratory rate (BIPAP S/T, Respironics Inc., Murrysville, PA, USA). The investigators of this study (1) previously reviewed the literature and found no randomized controlled trials of NIPPV for acute respiratory failure. Their study is randomized and unblinded, has appropriate inclusion and exclusion criteria, and contains carefully studied physiologic variables. A clinically important decrease was seen in patients in the NIPPV group who required intubation, but the trial was not large enough to detect any difference in mortality (only 1 patient receiving NIPPV and 2 receiving usual care died). The PaCO2 did not improve for 1 of 2 reasons: 1) NIPPV was used at a lower level (8.8 cm H2O) in this study than in other studies, causing lower tidal volumes, or 2) carbon dioxide was rebreathed when expired gas was not vented through the standard (Whisper-Swivel) exhalation device in the ventilator circuit (2). Maximal inspiratory pressure increased significantly after 6 hours of NIPPV, indicating a rapid reversal of diaphragmatic fatigue; however, the duration of ventilation was similar for patients receiving NIPPV and those who were intubated (8.7 vs 8.8 d).

NIPPV should be offered to patients with acute respiratory failure who refuse intubation and to those in whom intubation must be avoided; however, its routine use in hypercapnic chronic obstructive pulmonary disease should not yet be recommended. Experience with the use of pressure-support ventilation is required, and a nonrebreather exhalation valve should be inserted in the circuit. We can look forward to further development of noninvasive approaches to ventilatory support.

Howard Levy, MD
University of New MexicoAlbuquerque, New Mexico, USA


1. Meyer TJ, Hill NS. Noninvasive positive pressure ventilation to treat respiratory failure. Ann Intern Med. 1994;120:760-70.

2. Ferguson GT, Gilmartin M. CO2 rebreathing during BiPAP ventilatory assistance. Am J Respir Crit Care Med. 1995;151:1126-35.

Editor's note

Subsequent studies (3, 4) have validated the results of the study by Kramer and colleagues.

3. Keenan SP, Kernerman PD, Cook DJ, et al. Effect of noninvasive positive pressure ventilation on mortality in patients admitted with acute respiratory failure: a meta-analysis. Crit Care Med. 1997;25:1685-92.

4. Antonelli M, Conti G, Rocco M, et al. A comparison of noninvasive positive-pressure ventilation and conventional mechanical ventilation in patients with acute respiratory failure. N Engl J Med. 1998;339:429-35.