As a result, a normal V/Q ratio is about 0.8.ĬOPD generally manifests with a low ventilation-perfusion ratio. This is because gravity pulls more blood towards the bottom of the lungs which creates a relatively greater perfusion in the bottom of the lung relative to the volume of air flow. In reality, there is a greater movement of air in the upper portions of the lung relative to perfusion. This would suggest that if equal volumes of air and blood meet each other in the lungs then we would have a V/Q ratio of 1 for the optimal movement of oxygen to the blood. A liter of blood holds about 200 mL of oxygen and a liter of air holds about 200 mL of oxygen. The ventilation-perfusion (V/Q) ratio is the ratio between the amount of air getting to the alveoli (the alveolar ventilation, V, in ml/min) to the amount of blood being sent to the lungs (the cardiac output, Q, in ml/min). Note that we expect to see a decrease in the FEV 1/ FVC ratio in patients with COPD. Many patients can have components of both. COPD is generally described as being predominantly caused by either emphysema pathophysiology (pink puffer) or chronic bronchitis pathophysiology (blue bloater). The most common cause of COPD is smoking. Some apparatus dead space may actually reduce total dead space, as an ETT bypasses the majority of anatomical dead space of the patient (nasopharynx).ĭead space from the patient.COPD is a group of lung disorders characterized by the obstruction of airflow in pulmonary airways. Types of Dead Spaceĭead space from equipment, such as tubes ventilator circuitry. Glomerular Filtration and Tubular Functionĭead space is the proportion of minute ventilation which does not participate in gas exchange. Functional Anatomy and Control of Blood Flow
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