Objective: To prevent gas exchange deterioration during translaryngeal tracheostomy (TLT) in patients with acute respiratory distress syndrome (ARDS) ventilation is maintained through a small diameter endotracheal tube (ETT; 4.0 mm i.d.) advanced beyond the tracheostoma. We report on the feasibility of uninterrupted ventilation delivered through a high-resistance ETT in ARDS patients, and relevant ventilatory adjustments and monitoring.
Design and setting: Prospective, observational clinical study in an eight-bed intensive care unit of a university hospital.
Patients: Eight consecutive ARDS patients scheduled for tracheostomy.
Interventions: During TLT volume control ventilation was maintained through the 4.0-mm i.d. ETT. Tidal volume, respiratory rate, and inspiratory to expiratory ratio were kept constant. Fractional inspiratory oxygen was 1. Positive end expiratory pressure (PEEP) set on the ventilator (PEEP(vent)) was reduced to maintain total PEEP (PEEP(tot)) at baseline level according to the measured intrinsic PEEP (auto-PEEP).
Measurements and main results: Data were collected before tracheostomy and while on mechanical ventilation with the 4.0-mm i.d. ETT. Neither PaCO(2) nor PaO(2) changed significantly (54.5+/-10.0 vs. 56.4+/-7.0 and 137+/-69 vs. 140+/-59 mmHg, respectively). Auto-PEEP increased from 0.6+/-1.1 to 9.8+/-6.5 cmH(2)O during ventilation with the 4.0-mm i.d. ETT. By decreasing PEEP(vent) we obtained a stable PEEP(tot) (11.4+/-4.3 vs. 11.8+/-4.3 cmH(2)O), and end-inspiratory occlusion pressure (26.7+/-7.4 vs. 28.0+/-6.6 cmH(2)O). Peak inspiratory pressure rose from 33.8+/-8.1 to 77.8+/-12.7 cmH(2)O.
Conclusions: The high-resistance ETT allows ventilatory assistance during the whole TLT procedure. Assessment of stability in plateau pressure and PEEP(tot) by end-inspiratory and end-expiratory occlusions prevent hyperinflation and possibly barotrauma.