Laboratory Evaluation of Cuff Pressure Control Methods

Automatic cuff pressure (P_cuff) 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_cuff; and that the change in mean P_cuff (ΔP_cuff) is zero during mechanical ventilation with controlled or uncontrolled P_cuff.

Experiments lasted 12 h, and 2 inspiratory pressure targets (P_insp) were established. We tested 3 automatic devices (Intellicuff Standalone, PressureEyes, and Tracoe) and one manual method for uncontrolled P_cuff. 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_I = 1.0 s, PEEP = 10 cm H₂O, and P_insp = 10 and 40 cm H₂O. For automatic cuff pressure control, we used a data acquisition system. For manual cuff pressure control, P_cuff was set once and measured after mechanical ventilation. Initial P_cuff was 25 cm H₂O, and ΔP_cuff was calculated as final mean P_cuff - initial mean P_cuff. Data for ΔP_cuff were compared with t tests and reported as mean (SD).

Airway pressure oscillations during ventilation were observed in P_cuff waveforms. For manual control, ΔP_cuff was -9.3 (2.1) cm H₂O for P_insp = 10 cm H₂O and -8.1 (1.1) cm H₂O for P_insp = 40 cm H₂O (vs 0, P < .001). There was no difference in ΔP_cuff for P_insp = 10 cm H₂O versus 40 cm H₂O (P = .21). ΔP_cuff was only ± 0.3 cm H₂O for automatic control, which we deemed clinically unimportant.

Automatic devices do not regulate ventilatory pressure oscillations, but they do control mean P_cuff and keep ΔP_cuff well below a clinically important threshold. The large ΔP_cuff seen with uncontrolled P_cuff warrants periodic monitoring. Further studies are needed to determine the source of ΔP_cuff and the physiologic effects of P_cuff oscillations during mechanical ventilation.