Introduction
Material and methods
Patients
Non-invasive ventilation protocol and definitions
Data collection
Statistical analysis
Results
Patients
No ARDS or mild ARDS (n = 47) | Moderate or severe ARDS (n = 66) |
P
| |
---|---|---|---|
Age, mean, years | 60 (± 15) | 61 (± 17) | 0.72 |
Male sex, n (%) | 30 (64%) | 45 (68%) | 0.62 |
SAPS II, points* | 33 (23 to 39) | 41 (30 to 51) | 0.0014 |
Immunosuppression or cancer, n (%) | 17 (36%) | 33 (50%) | 0.15 |
Characteristics at admission before NIV
| |||
Sepsis, n (%) | 27 (73%) | 53 (70%) | 0.72 |
Systolic arterial pressure, mmHg | 131 (± 25) | 127 (± 27) | 0.43 |
Heart rate, beats/minute | 114 (± 25) | 110 (± 26) | 0.43 |
Respiratory rate, cycles/minute | 33 (± 7) | 33 (± 7) | 0.78 |
Glasgow coma scale, points* | 15 (15 to 15) | 15 (15 to 15) | 0.75 |
pH, units* | 7.4 (7.43 to 7.49) | 7.45 (7.40 to 7.48) | 0.24 |
PaCO2, mm Hg | 34.6 (± 6.3) | 35.4 (± 5.0) | 0.43 |
PaO2, mm Hg | 77 (± 41) | 85 (± 54) | 0.43 |
Bicarbonates, mmol/L | 25.0 (± 4.8) | 24.5 (± 5.0) | 0.58 |
Lactates, mmol/L* | 1.4 (1.0 to 2.0) | 1.9 (1.1 to 2.6) | 0.054 |
At 1 h of NIV initiation
| |||
pH* | 7.46 (7.39 to 7.49) | 7.42 (7.38 to 7.46) | 0.03 |
PCO2, mm Hg | 36.1 (± 6.6) | 37.8 (± 7.4) | 0.21 |
PaO2/FiO2, mm Hg* | 266 (219 to 330) | 124 (94 to 164) | <0.0001 |
PEEP level, cm H2O | 4.7 (± 1.1) | 4.5 (± 1.1) | 0.46 |
PS level, cm H2O* | 8.0 (6.5 to 10) | 8.0 (6 to 8) | 0.46 |
Tidal volume, ml | 579 (± 174) | 613 (± 173) | 0.37 |
Respiratory rate, breaths/minute* | 34.5 (25 to 40) | 32 (26 to 37.5) | 0.45 |
Outcome
| |||
Duration of NIV Day 1, hours* | 6.8 [4.0 to 10.0] | 5.2 [2.0 to 10.0] | 0.19 |
Total duration of NIV, days* | 2.0 [1.0 to 3.0] | 1.0 [1.0 to 2.5] | 0.17 |
Rate of NIV Failure, n (%) | 16 (34%) | 45 (68%) | 0.0003 |
Length of stay in ICU, days* | 8.0 [5.0 to 15.0] | 10.0 [6.0 to 14.0] | 0.53 |
ICU mortality, n (%) | 7 (15%) | 21 (32%) | 0.04 |
Rates of NIV failure and in-ICU mortality
Factors associated with NIV failure
NIV Success N = 52 | NIV Failure N = 61 | Univariate HR [95% CI]; P-value | Cox regression aHR [95% CI]; P-value | |
---|---|---|---|---|
Age, years | 58.0 (± 17.1) | 62.6 (± 14.4) | 1.47 [0.99 to 1.02]; P = 0.142 | - |
Male sex, n (%) | 36 (69%) | 39 (64%) | 0.85 [0.51 to 1.44]; P = 0.551 | - |
SAPS II | 31.4 (± 10.9) | 46.3 (± 18.2) | 1.05 [1.03 to 1.06]; P <0.001 | Not included |
Immunosuppression/cancer, n (%) | 20 (38%) | 30 (49%) | 1.30 [0.79 to 2.16]; P = 0.169 | - |
Cancer, n (%) | 0 (0%) | 8 (13%) | 4.36 [2.01 to 9.44]; P <0.001 | 2.74 [1.22 to 6.15]; P = 0.014 |
At Admission before VNI
| ||||
Sepsis, n (%) | 37 (71%) | 43 (70%) | 0.97 [0.56 to 1.68]; P = 0.913 | - |
Glasgow coma score | 14.9 (± 0.5) | 14.6 (± 1.2) | 0.84 [0.69 to 1.03]; P = 0.098 | 0.77 [0.63 to 0.96]; P = 0.018 |
Respiratory Rate, breaths/minute | 32.7 (± 7.0) | 33.3 (± 6.6) | 1.01 [0.97 to 1.05]; P = 0.517 | - |
pH | 7.44 (± 0.06) | 7.44 (± 0.08) | 2.16 [0.05 to 89.3]; P = 0.685 | - |
PaO2, mm Hg | 78.7 (± 43.0) | 84.1 (± 53.2) | 1.00 [0.99 to 1.01]; P = 0.442 | - |
PaCO2, mm Hg | 34.8 (± 5.6) | 35.3 (± 6.0) | 1.01 [0.97 to 1.06]; P = 0.669 | - |
Bicarbonates, mmol/L | 24.4 (± 4.8) | 25.5 (± 5.0) | 1.01 [0.96 to 1.06]; P = 0.547 | - |
Lactates, mmol/L | 2.0 (± 1.8) | 1.9 (± 1.2) | 1.00 [0.85 to 1.18]; P = 0.940 | - |
Heart rate, beats/minute | 114 (± 27) | 110 (± 25) | 0.99 [0.98 to 1.01]; P = 0.467 | - |
Shock, n (%) | 4 (8%) | 14 (23%) | 2.08 [1.14 to 3.79]; P = 0.017 | 1.89 [1.01 to 3.53]; P = 0.047 |
Systolic arterial pressure, mmHg | 134 (± 27) | 124 (± 24) | 0.99 [0.98 to 1.00]; P = 0.055 | Not included |
At NIV initiation
| ||||
Altered consciousness, n (%) | 3 (6%) | 8 (13%) | 1.71 [0.81 to 3.59]; P = 0.158 | - |
pH | 7.43 (± 0.06) | 7.41 (± 0.10) | 0.12 [0.00 to 4.31]; P = 0.244 | - |
PCO2, mm Hg | 36.6 (± 6.7) | 37.5 (± 7.5) | 1.02 [0.98 to 1.05]; P = 0.327 | - |
PaO2/FiO2, mm Hg | 211 (± 86) | 163 (± 92) | 0.99 [0.99 to 0.99]; P = 0.003 | Not included |
Moderate or severe ARDS, n (%) | 21 (40%) | 45 (74%) | 2.79 [1.57 to 4.95]; P < 0.001 | 2.57 [1.33 to 4.75]; P = 0.003 |
PaO2/FiO2 <150 mm Hg, n (%) | 12 (23%) | 37 (61%) | 2.97 [1.77 to 4.99]; P < 0.001 | Not included |
PEEP level, cm H2O | 4.8 (± 1.0) | 4.4 (± 1.3) | 0.77 [0.62 to 0.94]; P = 0.011 |
0.71 [0.57 to 0.88]; 0.002
|
PS level, cm H2O | 8.1 (± 2.2) | 8.0 (± 1.9) | 0.98 [0.86 to 1.13]; P = 0.915 | - |
Tidal volume, ml | 576 (± 144) | 619 (± 196) | 1.00 [0.99 to 1.00]; P = 0.157 | - |
Respiratory rate, breaths/minute | 32.7 (± 12.9) | 33.9 (± 9.0) | 1.01 [0.98 to 1.03]; P = 0.601 | - |
Important leaks, n (%) | 2/43 (5%) | 3/48 (6%) | 1.39 [0.43 to 4.48]; P = 0.720 | - |
Poor tolerance, n (%) | 3/43 (7%) | 9/48 (19%) | 2.08 [1.00 to 4.30]; P = 0.049 | 1.97 [0.89 to 4.30]; P = 0.09 |
Discussion
NIV failure rate in patients with acute hypoxemic respiratory failure
Time to intubation and impact on outcome
Predictive factors for NIV failure
Limitations
Conclusion
Key messages
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Intubation rates significantly differed between ARDS and non-ARDS patients and according to clinical severity of ARDS: 31% in mild, 62% in moderate and 84% in severe ARDS.
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NIV may be used as the first-line ventilatory support in mild ARDS whereas it does not appear beneficial in severe ARDS.
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In patients with moderate ARDS, NIV may be worth attempting in those having a PaO2/FiO2 ratio >150.
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The time to intubation after NIV failure did not seem to influence outcome of patients.
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Active cancer, shock, moderate/severe ARDS, lower Glasgow coma score and lower positive end-expiratory pressure level at NIV initiation were predictors of NIV failure.