Invasive mechanical ventilation (IMV) is the mainstay of supportive care in acute respiratory failure. However, maintaining ventilatory support beyond what is necessary may increase the risk of nosocomial infections, favour respiratory muscle atrophy, prolong ICU stay and increase hospital costs. Similarly, premature withdrawal of ventilatory support may increase ICU patient mortality by requiring reintubation. The MV weaning process is nothing more than the set of procedures that lead to the restoration of normal ventilation of the patient, freeing him/her from ventilatory support and eventually also from an artificial airway. This is a gradual process that can take a significant amount of hospitalisation time, so much so that it could even correspond to 40% of the entire period of ventilatory support. Currently, the process of disconnection from IMV is based on the performance of a spontaneous ventilation test (SVT) either with an unsupported oxygen source or with low ventilator support , with a duration of 30 to 120 minutes. One of the causes that may condition the viability of SVT is respiratory muscle weakness, which may be ventilator-induced. This condition is a syndrome characterised by the appearance of diffuse and symmetrical muscle weakness affecting 26-65% of patients mechanically ventilated for more than 5 days. Muscle wasting has been demonstrated by ultrasonography with an 18% reduction in the cross-sectional area of the rectus femoris muscle on the 10th day of evolution. This syndrome is associated with an increase in mechanical ventilation time and a 2 to 5-fold increase in mortality. Based on the above, the assessment of respiratory muscle strength should form part of the disconnection protocols of our units. The most studied parameters that provide us with information on patient readiness to face this process are f/Vt, PIM and P(O.1). Recently, the study of the diaphragm by ultrasonography is becoming a valid alternative technique for the study of the state of the muscle most involved in spontaneous breathing.
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Peak Inspiratory Pressure
Timeframe: 5 minutes, 24 hours