Background
High intensity NIV (Hi-NIV) is a pressure limited ventilation with IPAP> 20 cm H2O which is expected to improve alveolar ventilation and reverse hypercapnia in patients with acute exacerbation of COPD.
Objective
To evaluate the efficacy and safety of Hi-NIV in hypercapnic respiratory failure due to acute exacerbation of COPD comparing it with low intensity NIV (Lo-NIV)
Patients & Methods
The targeted IPAP was to obtain tidal volume 8 ml/kg IBW and SpO2 >90%. After 2hours of NIV initiation, patients were classified into 2 groups low and high intensity NIV according to the required IPAP level (Lo-NIV group if IPAP ? 20cmH2O and Hi-NIV group if IPAP > 20cmH2O).
Results
Hi-NIV group (16 patients) and Lo-NIV group (24 patients) were compared after 2 hours, 6 hours, 24 hours, and before discontinuation.
The following table compare both groups after 2hours NIV
| Parameter |
Lo-NIV Mean ± SD |
Hi-NIV Mean ± SD |
p value |
| RR breath/min | 24.25 ± 6.41 | 24.80 ± 4.28 | NS |
| pH | 7.36 ± 0.02 |
7.31 ± 0.04 |
< 0.001 |
| PaCO2 mmHg | 62.70 ± 14.03 |
76.40 ± 12.65 | < 0.01 |
| SaO2 % | 94.55 ± 2.96 |
93.45 ± 9.17 | NS |
| PEEP | 5.45 ± 0.94 |
6.40 ± 1.14 | < 0.01 |
| Peak inspirstory pressure | 19.25 ± 1.83 |
23.75 ± 1.77 | < 0.001 |
There were no significant difference between both group regarding the duration on NIV and ICU stay. The gastric insufflation and nasal and oral dryness were significantly (p<0.05) higher among Hi-NIV group.
Conclusion:
Both low and high intensity NIV can avoid intubation and improve clinical and gasometric parameters in patients with hypercapnic respiratory failure due to acute exacerbation of COPD.There is no need for high intensity NIV except in patients with marked hypercapnia resistant to low intensity NIV.