Abstract

Background: There is evidence supporting the benefits of non-invasive ventilation (NIV) in the treatment of acute respiratory failure (ARF), however, the role of different variables in the evaluation of this technique’s success are controversial. Objective: To evaluate the performance of the different clinical parameters and relate them with the success and failure of NIV in patients with ARF. Methodology: Prospective study of descriptive cohort that includes consecutive patients who fulfilled criteria of connection to NIV and entered to the ICU (Intensive Care Unit)of Clínica Alemana de Santiago between March of 2005 to July 2007. These patients were divided into two groups, those presenting failure with NIV and required intubation, failure group (GF) and those that did not require it, success sgroup (GE). The demographic registered variables measured were APACHE II, diagnosis of entrance were registered. The respiratory mechanics, arterial gasometry and haemodynamics were obtained at three moments of the evolution previous to the connection, the two hours and at the end of the use of NIV (pre-intubation and weaning of NIV). Results: From the 132 patients included, intubation was avoided in 99 of them (75 percent) 33 percent were entubated from which only 1 died. The pH was lower in the FG (7.42 +/- 0.06v/s 7.39 +/- 0.08; p = 0.04). The oxygen saturation by pulsometry (SpO2), was also lower in the GF after two hours (96+/-2 v/s 95+/-3; p =0.01) and at the end of NIV use (96+/-2 v/s 95+/-3; p =0.04). The PaO2/FiO2 was lower in the same group, at the three moments of measurement previous to the connection (196+/-66 v/s 144+/-59; p =0.001), two hours post connection (223+/-92 v/s 179+/-88; p =0.022) and at the end of the NIV use (252+/-78 v/s 208+/-104; p =0.021). At the end of the NIV use both, the cardiac frequency (FC) (86+/-16 v/s94+/-20; p =0.03) and the IPAP level (12+/-2 v/s 13+/-3; p=0.02)...