25 Aug 06
By E Garpestad and NS Hill
Critical Care 2006, 10:147
The selection of patients with acute lung injury/acute respiratory distress syndrome (ALI/ARDS) to receive noninvasive ventilation (NIV) is challenging, partly because there are few reliable selection criteria. The study by Rana and colleagues in the previous issue of Critical Care identifies metabolic acidosis and a lower oxygenation index as predictors of NIV failure, although it is unable to identify threshold values. It also demonstrates that treating patients with NIV for ALI/ARDS and shock is an exercise in futility. Future studies need to focus on criteria that will enable selection of patients for whom NIV will have a high likelihood of success
20 May 06
By S Rana, H Jenad, PC Gay, C F Buck, RD Hubmayr and O Gajic
Critical Care 2006, 10:R79
The role of non-invasive positive pressure ventilation (NIPPV) in the treatment of acute lung injury (ALI) is controversial. We sought to assess the outcome of ALI that was initially treated with NIPPV and to identify specific risk factors for NIPPV failure.
In this observational cohort study at the two intensive care units of a tertiary center, we identified consecutive patients with ALI who were initially treated with NIPPV. Data on demographics, APACHE III scores, degree of hypoxemia, ALI risk factors and NIPPV respiratory parameters were recorded. Univariate and multivariate regression analyses were performed to identify risk factors for NIPPV failure.
Of 79 consecutive patients who met the inclusion criteria, 23 were excluded because of a do not resuscitate order and two did not give research authorization. Of the remaining 54 patients, 38 (70.3%) failed NIPPV, among them all 19 patients with shock. In a stepwise logistic regression restricted to patients without shock, metabolic acidosis (odds ratio 1.27, 95% confidence interval (CI) 1.03 to 0.07 per unit of base deficit) and severe hypoxemia (odds ratio 1.03, 95%CI 1.01 to 1.05 per unit decrease in ratio of arterial partial pressure of O2 and inspired O2 concentration – PaO2/FiO2) predicted NIPPV failure. In patients who failed NIPPV, the observed mortality was higher than APACHE predicted mortality (68% versus 39%, p < 0.01).
NIPPV should be tried very cautiously or not at all in patients with ALI who have shock, metabolic acidosis or profound hypoxemia.
28 Mar 06
By KM Ho, K Wong
Critical Care 2006, 10:R49 http://ccforum.com/content/10/2/R49
We conducted the present study to investigate the potential beneficial and adverse effects of continuous positive airway pressure (CPAP) compared with bi-level positive airway pressure (BiPAP) noninvasive ventilation in patients with cardiogenic pulmonary oedema.
We included randomized controlled studies comparing CPAP and BiPAP treatment in patients with cardiogenic pulmonary oedema from the Cochrane Controlled Trials Register (2005 issue 3), and EMBASE and MEDLINE databases (1966 to 1 December 2005), without language restriction. Two reviewers reviewed the quality of the studies and independently performed data extraction.
Seven randomized controlled studies, including a total of 290 patients with cardiogenic pulmonary oedema, were considered. The hospital mortality (relative risk [RR] 0.76, 95% confidence interval [CI] 0.32–1.78; P = 0.52; I2 = 0%) and risk for requiring invasive ventilation (RR 0.80, 95% CI 0.33–1.94; P = 0.62; I2 = 0%) were not significantly different between patients treated with CPAP and those treated with BiPAP. Stratifying studies that used either fixed or titrated pressure during BiPAP treatment and studies involving patients with or without hypercapnia did not change the results. The duration of noninvasive ventilation required until the pulmonary oedema resolved (weighted mean difference [WMD] in hours = 3.65, 95% CI -12.12 to +19.43; P = 0.65, I2 = 0%) and length of hospital stay (WMD in days = -0.04, 95% CI -2.57 to +2.48; P = 0.97, I2 = 0%) were also not significantly different between the two groups. Based on the limited data available, there was an insignificant trend toward an increase in new onset acute myocardial infarction in patients treated with BiPAP (RR 2.10, 95% CI 0.91–4.84; P = 0.08; I2 = 25.3%).
BiPAP does not offer any significant clinical benefits over CPAP in patients with acute cardiogenic pulmonary oedema. Until a large randomized controlled trial shows significant clinical benefit and cost-effectiveness of BiPAP versus CPAP in patients with acute cardiogenic pulmonary oedema, the choice of modality will depend mainly on the equipment available.