PURPOSE: Nemerous applications of Nonivasive Positive Pressure Ventilation (NPPV)in patients with acute respiratory failure (RF)have been described but only a few are supported by strong literature data; in the other hand few evidence are available about predictors of NIV failure or success. Sometimes endotracheal intubation (ETI)and conventional ventilation (CV)could be improperly delayed due to application of NPPV. Aim of this study was to evaluate if biochemical data, ABG analysis, vital paramethers colud predict NPPV success or failure in a group of pts. admitted in our Respiratory Intensive care Unit (RICU) for ARF and severe respiratory acidosis.
METHODS: We analysed the medical records, prospectively collected, of pts. admitted to our RICU due to acute RF in the last 3 years.Inclusion criteria was acute RF and a respiratory acidosis with pH lower than 7.30. Exclusion criteria were: ETI before or at RICU admission, tracheostomy at admission, patients with advanced cancer or no-intubate order. We collected the principal vital parameters, biochemical data, Apache II score, ABG analysis at baseline and after 1h,12 h of NPPV by facial mask. CV by ETI was performed in case of NPPV failure.Statistical analysis: data are in mean±SD; we used unpaired t test with Welch correction to compare means; a p<0.05 was considered significant.
RESULTS: We include 125 pts. (age 75.6±12, 72 male) suffering from COPD exacerbation, lower respiratory tract infection, neuromuscolar disease, restrictive disease.The patients that failed with NPPV treatment had a significant lower pH after 1 hour of ventilation, a higher leucocytes count and PCR value at baseline. Failure rate was higer in hypoxemic and non COPD patients. There was no significant difference in basal Apache II score, RR, mean blood pressure and other biochemical parameters. The mortality rate and hospital stay was lower in the NPPV success group.
CONCLUSIONS: This observational study confirm that improvement of ABG analysis, in particul pH value after the first hour of treatment,is crucial to evaluate efficacy of NPPV in acute RF. Other paramethers, such us leucocytes count,PCR, hypoxemia at admission can help to predict failure or success of NIV.
CLINICAL IMPLICATIONS: NPPV can be very effective in the treatment of acute RF with severe respiratory acidosis, expecially in COPD exacerbations. A complete evaluation of patients and a strict observation in the first hours of treatment is very important to avoid delaying a necessary ETI and conventional ventilation.
DISCLOSURE: The following authors have nothing to disclose: Stefano Baglioni, Elvio Scoscia, Maurizio Dottorini, Oronzo Penza
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