Arterial oxygenation does not predict the outcome of patients with acute respiratory failure needing mechanical ventilation

Abstract

A Ar rt te er ri ia al l o ox xy yg ge en na at ti io on n d do oe es s n no ot t p pr re ed di ic ct t t th he e o ou ut tc co om me e o of f p pa at ti ie en nt ts s w wi it th h a ac cu ut te e r re es sp pi ir ra at to or ry y f fa ai il lu ur re e Using a discriminant multivariate analysis, the following variables were selected as the best predictors of outcome: 1) the number of associated complications (NAC) on admission; 2) the simplified acute physiologic score (SAPS); 3) oxygenation index (PAO 2 -AaPO 2 )/PAO 2 + 0.014 positive end-expiratory pressure (PEEP); and 4) the age of the patients.Using these predictors, 84% of the patients were accurately classified as survivors or as nonsurvivors. The partial contribution of each predictor to the model was also assessed using a logistic regression, by eliminating each single predictor and each possible pair of predictors. Using this means of analysis, the NAC and SAPS were the only predictors of mortality. The inclusion of short-term mechanicallyventilated patients did not bias the accuracy of prediction.

The impact of respiratory variables on mortality in non-ARDS and ARDS patients requiring mechanical ventilation

“…Age, APS and presence of chronic disease were associated with mortality in non-ARDS, while the initial severity of oxygenation defect was not. This is in agreement with findings by JimØnez and co-workers [5]. They found that the major condition influencing ICU mortality in patients with ARF was the severity of acute illness at admission and that the best predictor for survival was the number of as-sociated complications on admission, simplified acute physiology score (SAPS) and age.…”

“…One of the reasons for this finding may be that they studied medical ICU patients, who may have a larger prevalence of co-morbidities than our mixed ICU population. Others have also shown the independently predictive contribution of severity of disease scoring in both non-ARDS [5] and ARDS patients [15].…”

“…Patients defined as suffering from acute respiratory failure (ARF), of which ALI/ARDS represent a subset with more compromised oxygenation, have a similar reported mortality close to 40 % [3,4]. In ARF, no variables reflecting the degree of respiratory failure at the time of diagnosis of ARF have been able to predict mortality [5]. However in ARDS, factors associated with mortality are aetiology of the respiratory failure, co-morbid conditions and the development of multiple organ failure [6,7].…”

Factors determining outcomes in adult patient undergoing mechanical ventilation: A “real-world” retrospective study in an Indian Intensive Care Unit

“…[ 36 ] Some studies failed to show any association between PaO 2 /FiO 2 ratio and mortality. [ 8 25 37 ]…”

Characteristics and Clinical Outcomes of Patients on Mechanical Ventilation in the Coronary Care Unit of a Tertiary Care Hospital in Bangladesh

“…Some studies failed to show any association between Pao2/Fio2 ratio and mortality. [49][50][51] was associated with a survival rate of less than 20% while peak inspiratory pressure of less than 30 cmH2o was associated with a survival rate of 60%. 52 Our study revealed an independent association between plateau pressure of more than 35cmH2o and decreased survival 53 Hill, and Holanda, et al, demonstrated in their study that nasal bridge injury is a common problem with NIMV.…”