what is relavance of dead space in mechanical ventilator

This is therefore termed anatomical dead space as it serves no respiratory function. This stretching is possibly harmful to the patient with the compromised lung, particularly in those patients with Acute Lung Injury (ALI) or Adult Respiratory Distress Syndrome (ARDS).Anatomic dead space is an important phenomenon in respiratory physiology whereby, owing to the fact that upper airways do not function as locations for gas exchange, and because of the tidal nature of ventilation, there is always a fraction of the inspired air that does not perform a physiologic function of exchanging carbon dioxide for oxygen. You also need to be aware that larger tidal volumes will lead to greater stretching of the alveoli as each breath goes in and out. So increasing the tidal volume or respiratory rate could actually reduce the minute ventilation because of the breath stacking potential. The air from the previous breath has not been exhaled fully before the next breath, so breaths start to stack on top of one another. This is very relevant if they are being given tidal volumes that are too large, or a respiratory rate that is too fast. So they might not be able to get the air out of their lungs before the next breath comes along when being mechanically ventilated. Those patients who are suffering with Chronic Obstructive Pulmonary disease (COPD), because of the physiological problems they are suffering, have problems getting the air out of their lungs. There maybe some situations where this rule needs some modification. If, however, you just increase the patients tidal volume with each breath, you do not increase the dead space at all. This process can increase the patients propensity to retain carbon dioxide. The problem however is that you are also increasing the amount of dead space ventilation you are giving them, as each additional breath also carries the same amount of dead space. If you do that then the ventilation of the patient will increase as every minute you are giving them additional breaths.

What is relavance of dead space in mechanical ventilator