Laboratory Evaluation of Cuff Pressure Control Methods

Automatic cuff pressure (P ) control devices for artificial airways are available, yet there are no standards or data to support their use. We hypothesized that airway pressure oscillations during mechanical ventilation are transmitted to P ; and that the change in mean P (ΔP ) is zero during mechanical ventilation with controlled or uncontrolled P . Experiments lasted 12 h, and 2 inspiratory pressure targets (P ) were established. We tested 3 automatic devices (Intellicuff Standalone, PressureEyes, and Tracoe) and one manual method for uncontrolled P . We utilized a training mannequin with an 8-mm endotracheal tube to assess pressure-controlled continuous mechanical ventilation with the following parameters: breathing frequency = 20 breaths/min, T = 1.0 s, PEEP = 10 cm H O, and P = 10 and 40 cm H O. For automatic cuff pressure control, we used a data acquisition system. For manual cuff pressure control, P was set once and measured after mechanical ventilation. Initial P was 25 cm H O, and ΔP was calculated as final mean P - initial mean P . Data for ΔP were compared with tests and reported as mean (SD). Airway pressure oscillations during ventilation were observed in P waveforms. For manual control, ΔP was -9.3 (2.1) cm H O for P = 10 cm H O and -8.1 (1.1) cm H O for P = 40 cm H O (vs 0, < .001). There was no difference in ΔP for P = 10 cm H O versus 40 cm H O ( = .21). ΔP was only ± 0.3 cm H O for automatic control, which we deemed clinically unimportant. Automatic devices do not regulate ventilatory pressure oscillations, but they do control mean P and keep ΔP well below a clinically important threshold. The large ΔP seen with uncontrolled P warrants periodic monitoring. Further studies are needed to determine the source of ΔP and the physiologic effects of P oscillations during mechanical ventilation.