Hello there,

Can any experts out there share with me in simple term on LEAK COMPENSATION MACHANISM; how this machanism work in any a ventilator. Thanks.

I will take a shot at this and if I find out more I will let you know. I hope someone better informed will chime in also. The place that I am most familiar with leak compensation is in non-invasive positive pressure ventilation (NPPV) or BiPAP. It is, in my experience a part of most modern NPPV delivery systems to determine a leak and adjust flow delivery to compensate for the flow lost via the leak in an attempt to keep pressure delivery and thus ventilation provided uncompromised even though a leak may exist. In single limb systems this is a calculation not in any way exact, but the more sophisiticated software on some of devices now is pretty accurate at calculating and compensating. With dual limbed circuits it can be a little more of a specific measurement gas delivered minus gas returned = gas loss and compensation can be adjusted. I will be at AARC this weekend and will take your question to the vendors. My current experience with the Hayek RTX I know it compensates for leaks with gradually increasing flow until the set pressures or maximal flow capacity is reached. It can be a relatively quiet device if no leaks are present, or it can sound like a jet on take off if leaks develop. As far as normal invasive positive pressure ventilation settings providing for leak compensation, I am not specifically aware of standard PPV settings on machines that offer this feature. I think it might not be needed as when invasive PPV is used it is used with a sealed or at least a somewhat sealed airway and gas loss is not a significant part of the equation as it would be with a non-invasive interface. Perhaps someone is aware of a vent that offers this outside of the non-invasive mode.

The PB 840 ventilator is equipped with additional software as an add-on to run NIV with Leak compensation. Other ventilator manufacturers offer this option. Successful NIV with a dual-limbed ventilator is an advanced technique which requires a non-vented mask through a dual limbed circuit. With masks, rather than an ETT, there are leaks that the ventilator must compensate for and the practitioner uses equipment to ventilate non-invasively.
There are advantages. Unfortunately, leak compensation is not in and of itself any guarantee that the patient is being adequately ventilated and settings, abg's, patient comfort, patient synchrony are all challenging in this set-up. Many therapists are apprehensive concerning the ventilation of a patient with an advanced ventilator in NIV mode and an appropriate fitting non-vented mask. There preference is too remove the ventilator and obtain a less complex method of noninvasive ventilation with a vented mask, and another type of leak compensating device.
It is not a mechanism, it is a threshold. Either device mentioned reaches a pressure-volume-time threshold. For example, NG tubes may be present and add an unintentional leak. Intentional leaks are "built in" and therefore calculated into software to compensate for flows and deviations.
With unintentional leaks the compensation threshold is often times prolonged until a expiratory threshold limitation is reached and the breath is cycled. The key to reducing leaks is minimization. You want to create an air-tight, minimized leak so that there isn't any machine compensation. This is for synchronization of inspiratory efforts and less WOB. (work-of-breathing). Best of luck.