Adaptive lung ventilation (ALV) is a new method of closed loop mechanical ventilation and is patient centered, ie, increase or decrease of ventilatory support is determined predominantly by the patient and not by the physician. In contrast to previously described forms of electronically controlled variable ventilatory support such as mandatory minute volume (MMV) ventilation, ALV is designed to adjust ventilation until optimal gross alveolar ventilation is achieved in paralyzed as well as spontaneously breathing patients. Inherent in the design of ALV is the ability to prevent excessive dead space ventilation, avoid inadvertent positive end-expiratory pressure (PEEP), and discourage rapid shallow breathing. These features, if confirmed by clinical studies, suggest that ALV would be safer and more comfortable than any other previously described form of mechanical ventilatory support and should be ideal for weaning patients.
The efficiency of ALV has been shown in lung models and in patients with normal lungs undergoing general anaesthesia. However, its ability to wean patients who have pulmonary disease, are ventilator dependent, and require changing levels of ventilatory support with subsequent careful weaning from the support has not yet been assessed. website
This study was designed to evaluate ALV in patients with different lung abnormalities when standard weaning criteria were met.
Adaptive lung ventilation uses synchronized intermittent pressure-controlled ventilation as its basic mode. The user chooses a desired gross alveolar ventilation (V’gA in liters per minute) and the ALV controller partitions the alveolar ventilation into a target volume and a target rate and then adjusts inspired pressure support, ventilator rate, and inspired/ expired time ratio to achieve the desired V’gA. The adjustments are based on measurements of the patient’s lung mechanics and series dead space (VdS), and are designed to achieve minimal work of breathing and avoid intrinsic PEEP.