Reconnection to the mechanical ventilator after a successful SBT: a little rest to prevent a return to the tube

Last update: Thursday, 28 Jun 2018 at 15:53

Written by:
- Marcelo Alcantara Holanda, MD Ph.D., Associate Professor of Pulmonology and Critical Care of the Federal University of Ceará (UFC), Idealizer and founder of the Xlung Plataform
- Davi Mota Alcantara, MD, Xlung Platform Consultant

The Brazilian Guidelines on Mechanical Ventilation (MV) (1) recommend withdrawing the patient from invasive ventilation as quickly as possible. Daily suspension of sedation and active search for identification of the patient who is a good candidate should be performed routinely to achieve this objective. Once identified, the Spontaneous Breathing Test (SBT) can be used to assess the patient's extubation readiness. In this scenario, a T-tube or PSV of 5-7cmH2O is employed for 30 to 120 minutes. Patients who maintain a good respiratory pattern, gas exchange, hemodynamic stability and comfort, without criteria for discontinuation of the SBT (Table 1) are considered successful (1).

Clinical and cardiorespiratory parameters for SBT interruption
Respiratory Rate > 35 rpm
SpO2 < 90%
Heart Rate > 140 bpm
Systolic blood pressure > 180 mmHg ou < 90 mmHg
Signs and symptoms: Agitation, sweating, altered level of consciousness

In case of a successful SBT, it should be assessed whether the airways are patent and protected. If that’s ok, extubation is then followed - with the possibility of using preventive noninvasive ventilation (NIV) in patients with risk factors for respiratory failure.

Ventilator-induced diaphragmatic dysfunction can be defined as a loss of the force-generating capacity of this muscle related to MV (3). In turn, the imposition of extra load on the diaphragm, such as during a SBT, could, in theory, predispose to post-extubation fatigue of this muscle. The optimal duration and conditions in which the SBT should be performed are still not consensual in the literature. Intense SBTs, for example, more than 30 min in T-tube, may have a higher [...]

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