11/4/2023 0 Comments Increased alveolar dead space![]() ![]() Thus making it more accessible and easy to monitor and study in large groups of patients, factors which have perhaps resulted in its under-utilisation in critical care. Several indices have been described that either predict deadspace or track ventilatory efficiency at the bedside. Recently though there has been a resurgence of interest in ventilatory efficiency. Deadspace and with it ventilatory efficiency has been largely forgotten. Yet indices of oxygenation seem to be the mainstay when instigating or fine-tuning ventilatory strategies. Since its first description by Bohr in the late 19th century to the current use of single-breath test for volumetric CO 2, our understanding of the physiological deadspace has vastly improved. Measuring deadspace ventilation should be the most reliable method of monitoring ventilatory efficiency in mechanically ventilated patients. Ventilation may exceed perfusion in parts of the lung resulting in increased physiological dead air space.Problems with ventilatory efficiency results in abnormal CO 2 clearance. Air may reach the periphery of the lungs but fail to make contact with the capillary blood. The alveoli become permanently damaged (see video above).This is why breathlessness and fatigue are common symptoms of COPD. This extra effort can make the patient feel very tired. However, this does not mean that your oxygen levels are low because the breathing muscles around the chest are working harder to compensate. The respiratory muscles then have to work harder to get air in and out of your lungs.As the lungs become hyper-inflated they elongate and flatten, which means the diaphragm does not work as well as it should. ![]() As a result, air gets trapped in the lungs and the lungs get bigger (hyper-inflated). ![]() These changes cause the air sacs (alveoli) to close before you have fully exhaled. In emphysema, exposure to an irritant over many years causes an inflammation in the lungs which causes the following changes: Please note there is no audio for this animation ![]()
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