The colored external portion of the LMA, the elbow connector, filter and the end of the breathing circuit are all equipment dead space. A poor mask seal, failure to squeeze the bag effectively, or allowing the patient to breath shallowly could all lead to hypoventilation in this scenario.Įxample of equipment dead space. This particular combination, including the LMA outside the mouth, the end of the breathing circuit, the bacterial/humidification filter, and the elbow adapter added an additional 50 ml of dead space. The colored portion shows equipment dead space. The photo shows the end of an anesthesia breathing circuit I recently used. Usually equipment dead space is small compared to the total tidal volume, but not always. Your manually administered breath must include enough volume to cover this equipment dead space to avoid hypoventilation. for more on physiologic dead space see:Įquipment dead space includes the mask, the part of the endotracheal tube or laryngeal mask airway (LMA) outside the patient’s mouth, even the elbow on the endotracheal tube connecting it to the ventilation bag. Decreased cardiac output or decreased lung perfusion increases pulmonary dead space by diminishing pulmonary capillary blood flow. Physiologic dead space changes from minute to minute. In Physiologic dead space, lack of capillary flow at the time of measurement prevents gas exchange. Anatomic Dead Space Affects Hypoventilation.To read an article on how anatomic dead space affects ventilation see: A third of the normal tidal volume is anatomic dead space, with a volume of about 2ml/kg in an adult and up to 3ml/kg in a baby. The lungs cannot absorb oxygen or eliminate carbon dioxide in anatomic dead space. These fixed parts of the respiratory tract are ventilated but not perfused. Anatomic Dead SpaceĪnatomic dead space does not have alveoli, such as the trachea, bronchi, and bronchioles. The 3 different types of dead space consist of anatomic, physiologic, and last, but not least, equipment. Ignoring equipment dead space can lead to significant hypoventilation. We often forget equipment dead space, the dead space belongs to any airway equipment used to assist ventilation. We often worry about anatomic and physiologic dead space. Make your own sentences using possessive case (10 sentences).Dead space is the portion of the respiratory system where tidal volume doesn’t participate in gas exchange. Make the sentences of your own using the new words (10 sentences). What is the most important parameter of lung function?
What does physiological dead space include?ĩ. Does gas exchange occur in trachea and bronchi?ħ. Is anatomic dead space equipment to the volume of the conducting airways?ĥ. Describe the process of total ventilation?Ĥ. Is total ventilation equal to the tidal volume?ģ. How minutes does it take for total ventilation?Ģ. The work of these students is interesting.
The children of my brother are at home.Ħ. It must be adequate for removal of the CO 2 produced by tissue metabolism whereas the partial pressure of inspired O 2 is 150 mmHg, the partial pressure of O 2 in the alveoli is typically 100 mmHg because of the displacement of O 2 with CO 2. Alveolar ventilation is the gas flow entering functional alveoli per minute.Īlveolar ventilation: It is the single most important parameter of lung function. Physiologic dead space can greatly exceed anatomic dead space in individuals with lung disease.ĭead space ventilation is the gas flow into dead space per minute. In normal individuals, anatomic and physiologic dead space are approximately equal. g., because of a pulmonan embolus preventing blood supply to a region of alveoli). It includes the anatomic dead space and partially functional or nonfunctional alveoli (e. Physiologic dead space is the volume of the respiratory tract that does not participate in gas exchange. e., the trachea and bronchi up to and including the terminal bronchioles. Total ventilation is the sum of dead space ventilation and alveolar ventilation.Īnatomic dead space is equivalent to the volume of the conducting airways (150 mL in normal individuals), i. It is equal to the tidal volume (VT) x the respiratory rate (n). Total ventilation (VT, minute ventilation) is the total gas flow into the lungs per minute.