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(Delta P-cuff) is zero during mechanical ventilation with controlled or uncontrolled P-cuff METHODS: Experiments lasted 12 h, and 2 inspiratory pressure targets (P-insp) were established. We tested 3 automatic devices (InteWenn' 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-1 = 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 Delta P-cuff was calculated as final mean P-cuff-initial mean P-cuff. Data for Delta P-cuff were compared with t tests and reported as mean (SD). RESULTS: Airway pressure oscillations during ventilation were observed in P euff waveforms. For manual control, Delta P-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 Delta P-cuff for P-insp = 10 cm H2O versus 40 cm H2O (P = .21). Delta P-cuff was only +/- 0.3 cm H2O for automatic control, which we deemed clinically unimportant. CONCLUSIONS: Automatic devices do not regulate ventilatory pressure oscillations, but they do control mean P-cuff and keep Delta P-cuff well below a clinically important threshold. The large Delta P-cuff seen with uncontrolled P-cuff warrants periodic monitoring. Further studies are needed to determine the source of Delta P-cuff and the physiologic effects of P-cuff oscillations during mechanical ventilation.