Dr. Rodrigo Souza da Silva

The importance of using the Train-of-Four (TOF) in the COVID-19 ICUs

The use of Neuromuscular Blockade (NMB) during mechanical ventilation in patients with Acute Respiratory Distress Syndrome (ARDS) improves (1) ventilatory support, (2) reduces mortality and has been used for many years in Intensive Care Units (ICUs). 

In the context of the COVID-19 pandemic, several patients are in need of mechanical ventilation and use of NMB for prolonged periods, often exceeding 10 days. This use is different from the indications in the usual ARDS, to which we were accustomed, in which the need for NMB was kept for short periods, usually 24 to 48 hours. This created a difficulty in the proper dosage and management of these drugs. In addition, this prolonged use in so many patients has led to a shortage of these drugs worldwide. 

The use of Neuromuscular Block monitors, such as Train-of-Four (TOF), is a well-established practice in anesthesiology during general anesthesia, with its indications, limitations and mechanisms well described and accepted by the entire medical community. This monitoring is necessary because the ideal dose is extremely variable among different people due to several factors such as age, sex, muscle mass and pre-existing diseases. In general anesthesia, in addition to the need to maintain the patient with an adequate level of NMB, we need to reverse this block at the end of the procedure for the possibility of safe extubation of the patient.

Now, in this new context, the use of TOF in the ICU allows the precise dosage of drugs, enabling better management of patients in addition to their more rational use, leading to savings in resources. 

The introduction of a new routine is accompanied by several challenges and possibilities for process failures. The TOF monitors which are available today in Brazil work through loose electrodes associated with an accelerometer attached to the region to be stimulated, usually the thumb. This method, although well established, has the problem of being affected by many factors, such as the position of the hand/arm, the electrodes, the accelerometer, objects limiting the movement of the finger, etc. in addition to impacting the routine of the ICU, both for the medical and nursing staff. 

The VISION DUO works through a non-invasive pressure cuff, equipment widely used in any ICU and therefore, does not cause any kind of estrangement to the team, greatly facilitating its introduction into the care routine. In addition, it can 

be easily switched between patients, without the need for additional material, such as electrodes.