Mechanical insufflation–exsufflation to facilitate ventilator weaning and possible decannulation for patients with encephalopathic conditions

Background

Clinicians are often faced with apparently tracheostomy mechanical ventilation dependent (TMV), patients who are ventilator unweanable due to encephalopathic/upper motor neuron conditions, that hamper return to the community.

Objectives

A protocol is suggested to wean these patients from mechanical ventilation and criteria offered for possible decannulation.

Methods

After excluding patients with severe muscle weakness due to neuromuscular diseases and high level spinal cord disorders, consecutive, apparently unweanable and unresponsive encephalopathic patients were to be weaned by a protocol that first normalized CO₂ levels at full ventilatory support settings. Then, supplemental oxygen was discontinued so that ambient air baseline oxyhemoglobin saturation (O₂ Sat) could be determined and subsequently be normalized by using mechanical insufflation–exsufflation (MIE), at 60–70 cmH₂O pressures, via the tubes every 2 hours, with the tube cuffs inflated. Once ambient air O₂ Sat levels remained normal, ambient air spontaneous, unassisted autonomous breathing “sprints” were initiated and continued until O₂ Sat decreased below 95% with respiratory distress. Patients spontaneously moving over 300 mL of air into their lungs without pressure support had very good prognoses for rapid ventilator weaning. Patients were not returned to TMV irrespective of tachypnea. After the “sprint”, they were rested by using 1–3 hours of full ventilatory support before the next sprint. Sprints lengthened until being fully weaned. After weaning, potential decannulation was evaluated using MIE expiratory flows (MIE-EF) and O₂ Sat.

Results

O₂ Sat normalized from the initial use of MIE via the tube for 7 of 13 patients then 4 weaned from the initial ambient air sprint. Weaning occurred in 4 days or less for 11 of 13. Despite continuous TMV dependence for 31 days to 15 months before the intervention, 7 weaned patients were successfully decannulated, 6 of the 7 with MIE-EF ≥ 190 L/m. All but 2 remained unresponsive, but 6 were discharged home to their families once decannulated.

Conclusion

Once primary ventilatory pump failure is excluded and lung disease improved to the extent that the ambient air O₂ Sat can be normalized by using MIE via invasive airway tubes to clear airway secretions, encephalopathic patients can have sufficient muscle strength to wean from ventilatory support and possibly be decannulated if mechanically augmented cough flows exceed 190 L/m.