Closed system endotracheal suctioning maintains lung volume during volume-controlled mechanical ventilation
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Objective: A closed suction system (CS) maintains connection with the mechanical ventilator during tracheal suctioning and is claimed to limit loss in lung volume and oxygenation. We compared changes in lung volume, oxygenation, airway pressure and hemodynamics during endotracheal suctioning performed with CS and with an open suction system (OS). Design: Prospective, randomized study. Setting: Intensive care unit in a university hospital. Patients: We enrolled ten patients, volume-controlled (VC) ventilated with a Siemens Servo 900 ventilator (PaO2/FIO2 192±70, PEEP 10.7±3.9 cmH2O). Interventions: We performed four consecutive tracheal suction maneuvers, two with CS and two with OS, at 20-min intervals. During the suction maneuvers continuous suction was applied for 20 s. Measurements and main results: We measured end-expiratory lung volume changes (ΔVL), tidal volume (VTrt), respiratory rate (RR) and minute volume (VErt) by respiratory inductive plethysmography; arterial oxygen saturation (SpO2), airway pressure and arterial pressure (PA). Loss in lung volume during OS (ΔVL 1.2±0.7 l) was significantly higher than during CS (ΔVL 0.14±0.1 l). During OS we observed a marked drop in SpO2, while during CS the change was only minor. During CS ventilation was not interrupted and we observed an immediate increase in RR (due to the activation of the ventilator's trigger), while VTrt decreased, VErt was maintained. Conclusions: Avoiding suction-related lung volume loss can be helpful in patients with an increased tendency to alveolar collapse; CS allows suctioning while avoiding dramatic drops in lung volumes and seems to be safe during the VC ventilation setting that we used.
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