What is the difference between invasive and non invasive ventilation? Cardiology Basics

What is the difference between invasive and non invasive ventilation? Cardiology Basics

Ventilator is a device used to support breathing. It is used when there is difficulty in breathing or when spontaneous breathing has stopped. Ventilator is an important life supporting device useful in many life threatening conditions.

Invasive ventilator is usually used in the intensive care setting or the operating room. An endotracheal tube is introduced under topical anaesthesia with sedation or general anaesthesia. The endotracheal tube is connected to a mechanical ventilator using appropriate connection tubing. In those who do not tolerate the presence of an endotracheal tube deep sedation and neuromuscular blockade will have to be given. A few patients do tolerate the endotracheal tube in the awake state without need for much sedation, especially after the initial few hours.

Ventilator senses the breathing needs of the individual and gives appropriate pressures to inflate the lungs to either replace the breathing efforts of the individual or supplement spontaneous breathing in various disease conditions. The tidal volume delivered and the maximum pressure at which it can be delivered can be adjusted in the ventilator settings. Using too much of positive pressure can cause barotrauma to the alveoli. Various alarm settings can also be tailored to individual needs.

Non-invasive ventilator is usually a smaller device with less sophistication. It is connected using an external mask which is tight fitting over the nostrils and mouth. A good air seal at the mask – face interface is needed for proper functioning of non-invasive ventilator. Too tight a mask can cause skin injury and discomfort to the person. Small noninvasive ventilators running on mains, with battery backup are being used by many sick long term care patients at home. Caretakers can be easily trained to apply the mask and check for air seal.

The advantage of non-invasive ventilation is that the individual can remain fully alert, without any need for sedation or anaesthesia. There is no need to place an endotracheal tube and hence can be initiated quickly by minimally trained persons. Alarm settings have to be adjusted for the needs of the patient to avoid unnecessary alarms.

The non-invasive ventilator usually supplies two levels of pressure – one during inspiration and another during expiration. Pressure applied during inspiration is higher than that in expiration. A simpler type uses continuous positive airway pressure and is known in short as CPAP, mostly used for obstructive sleep apnea.

Non-invasive ventilation with different pressures in inspiration and expiration is known as bi-level positive airway pressure or BiPAP ventilation. Inspiratory positive airway pressure is known as IPAP and expiratory positive airway pressure as EPAP. IPAP and EPAP can be adjusted according to the physiological needs of the patient.