The Effectiveness of High Flow Nasal Cannula Versus Noninvasive Ventilation and Conventional Oxygen Therapy in Patients Weaned from Invasive Mechanical Ventilation:

Reintubation after liberation from mechanical ventilation (MV) is a wellknown adverse event seen in different patients subtypes(post surgical, trauma,medical) as well as in surgical and medical intensive care units (ICUs) .The cumulative probability of reintubation , following planned and unplanned extubation , in 185 ICUs in the United States ,reached up to 10 % and 90% occurred within the first 96 hours (4 days) after first extubation , the median time to reintubation was 15 hours.

Proper timing for extubation is crucial to minimize extubation failure and about 12 to 14% of patients planned for extubation would require reintubation within 48 to 72 hours, mostly within the first 24 hours & in a multivariate analysis, duration of MV more than 7 days prior to extubation, ineffective cough, and severe systolic left ventricular dysfunction were independent factors associated with extubation failure, whereas ,in another study,age and underlying diseases were other factors associated with higher extubation failure with rates reaching up to 34% in patients 65 yrs or older, those with chronic respiratory or cardiac disorders and the condition was specifically associated with significant rapid clinical deterioration and worsening of daily organ dysfunction scores reflecting a direct effect of reintubation on patient outcomes. Mortality risk is reported to be five times higher in patients who require reintubation after extubation from MV.

Postextubation sequential oxygen devices applied as first-line therapy after extubation include noninvasive ventilation (NIV) , high-flow nasal cannula (HFNC) and conventional oxygen therapy (COT).

COT delivered via masks and nasal prongs has been widely used as the main sequential supportive oxygen therapy administered to patients after extubation . However, the maximal oxygen flow rates that these devices can deliver are limited with maximum flow rate up to 15 L/min only, which is usually far lower than the demands that postextubation patients would require . The fraction of inspired oxygen (FiO2) delivered by COT is unstable because of the entertainment of room air and dilution of the inspired oxygen .

Potential benefits of NIV include the ability to provide a relatively consistent and wider range of FiO2 compared with COT . Moreover, NIV creates an extrinsic positive end expiratory pressure which aids in recruitment of collapsed alveoli.