Non-invasive mechanical ventilation after the successful weaning: where are the limits of venturi mask?

Dear Editor,

Weaning from mechanical ventilation is one of the most challenging decisions in the Intensive Care Unit (ICU), due to high mortality rate associated with the cases that fail extubation. Moreover, despite successful weaning tests available on average around 20% of the patients will need a reintubation, facing a dramatic decline on their clinical outcomes.

Adıyeke et al.¹ on their study tackle the impact of None Invasive Mechanical Ventilation (NIMV) on the patient's outcome during the weaning process and the extubation period through the comparison with Venturi Mask, As a final disclosure the authors recommend the use of NIMV unless for a minimum of 48 h after extubation due to the noticed reduction on the respiratory failure and the length of stay on ICU.

Nevertheless, after carefully analyzing this study we consider that there are some key practical regards needed to take into account.

First, Adıyeke et al.¹ expand the recommendation for the NIMV not only to the high reintubation risk patients but also to the ones likely to developed an acute respiratory failure requiring a reintubation. This is in opposite direction regarding other previous larger studies based on data from Esteban et al.,² Nava et al.,³ and larger meta-analysis, regarding the none invasive mechanical ventilation role in the postextubation respiratory failure.⁴ Those papers showed benefit on mortality rates only when NIMV applied to selected patients, specifically when underlying cardiac or respiratory disease exists.

Second, only 50 patients were considered, translating in a small group, which probably limits considerably the aftermath. No significant reduction on mortality or reintubation rates was seen. However other studies, Ferrer et al.,⁵ showed a relevant decrease in mortality. These differences may presumably be because of the small sample size observed. Of note in both of the studies, Adıyeke et al.¹ and Ferrer et al.⁴ agreed on the lack of 90 day survival rates differences among the two groups. But no data on the destination ward type after downgrade from the ICU, for example intermediate, telemetry or regular medical wards. As seen in our daily practice, the transition to plain medical wards sometimes is poorly tolerated. No data available to confirm nor denied the hypothesis but maybe this aspect should be taken into account when thinking on the 90 day survival rate.

Third, the study lacks to mention patient's underlying clinical conditions. Bearing in mind that three out of the four main NIMV indications are Acute on chronic respiratory failure, cardiogenic respiratory edema and weaning from ventilator, it would be logical to think of those special NIMV benefits and applying them to the patients with underlying cardiac or respiratory disease, along the weaning process.

As seen in the recent paper from Thille et al.,⁶ the implementation of prophylactic NIMV protocols after extubation may reduce the reintubation rate when those requirements are met. On the cardiac side the authors admitted a wide range of cardiovascular entities (valvulopathies, ischemia, arrhythmic diseases) having all of them in common the acute cardiac failure. The positive pressure ventilation effects on hemodynamics, when the patient is properly hydrated, is to improve the left cardiac output through the increase on pre-load and the decrease after-load, so reinforcing the cardiovascular balance and eliminating one of the potential causes of failure to weaning and reintubation. As seen on the paper, in these type of patients, the weaning process uses the Pressure-Support (PS) modality rather than T-piece, without losing the positive pressure effects on the cardiac outcome, even for a little time, and then increasing the weaning success. Looking at the side dealing with respiratory conditions, we find chronic lung diseases, obstructive, restrictive, even obesity-hypoventilation syndrome which belongs to the natural NIVM framework for the respiratory support. So using the non invasive mechanical ventilation on the weaning and later on, we offer a "soft landing" to the ill lung after the intubation period, and doing so once again, we reduce significantly the reintubation rate.

We agree that further and larger clinical research is demanded, to elucidate the role of complete NIMV in the clinical evolution of the patient along the post-extubation stage.

References

• ¹ Adıyeke E, Ozgultekin A, Turan G, et al. Non-invasive mechanical ventilation after the successful weaning: a comparison with the venturi mask. Rev Bras Anestesiol. 2016;66:572-6.
• ² Esteban A, Frutos-Vivar F, Ferguson ND, et al. Noninvasive positive-pressure ventilation for respiratory failure after extubation. Engl J Med. 2004;350:2452-60.
• ³ Nava S, Gregoretti C, Fanfulla F, et al. Noninvasive ventilation to prevent respiratory failure after extubation in high-risk patients. Crit Care Med. 2005;33:2465-70.
• ⁴ Agarwal R, Aggarwal AN, Gupta D, et al. Role of noninvasive positive-pressure ventilation in postextubation respiratory failure: a meta-analysis. Respir Care. 2007;52:1472-9.
• ⁵ Ferrer M, Valencia M, Nicolas JM, et al. Early noninvasive ventilation averts extubation failure in patients at risk: a randomized trial. Am J Respir Crit Care Med. 2006;15:164-70.
• ⁶ Thille AW, Boissier F, Ben-Ghezala H, et al. Easily identified at-risk patients for extubation failure may benefit from noninvasive ventilation: a prospective before-after study. Crit Care. 2016;20:48.

Publication Dates

• Publication in this collection
  Jan-Feb 2018