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Information about Body Plethysmography

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Body plethysmography is a method of obtaining the absolute volume of air within one's lungs. It is used in situations where several repeated trials are required or where the patient is unable to perform the multibreath tests.

The patient is enclosed in an airtight chamber often referred to as a body box; a pneumotachometer is used to measure airflow while a mouth pressure transducer with a shutter measures the alveolar pressure. The most common measurements made using body plethysmographs are thoracic gas volume (VTG) and airway resistance (RAW). This test is used mainly in the Pulmonary Function Testing laboratories.

Using body plethysmography, doctors can examine the lungs' resistance to airflow, distinguish between restrictive and obstructive lung diseases, determine the response to bronchodilators, and determine bronchial hyperreactivity in response to metacholine, histamine, or isocapnic hyperventilation.

Flow and Pressure Plethysmographs

There are two types of plethysmographs: flow and pressure. In flow plethysmography, airway resistance is measured by two maneuvers. The patient first pants while the mouth shutter is open to allow flow changes to be measured. Then, the mouth shutter closes at the patient's end expiratory or FRC level and the patient continues panting while maintaining an open glottis. This provides a measure of the driving pressure used to move air into the lungs.

Pressure plethysmographs are usually measured at the end-expiratory level and are then equal to FRC. The patient sits in the box, which has the pressure transducer in the wall of the device, and breathes through a mouthpiece connected to a device that contains an electronic shutter and a differential pressure pneumotachometer. The mouth pressure and box pressure changes that are measured during tidal breathing and panting maneuvers which are performed during the test by the patient at the end of expiration are sent to a microprocessor unit that calculates thoracic gas volume.

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Respiratory system, physiology: respiratory physiology
Volumeslung volumes - vital capacity - functional residual capacity - respiratory minute volume - dead space - spirometry - body plethysmography - peak flow meter
Airwaysventilation (V) (positive pressure) - breath (inhalation, exhalation) -respiratory rate - respirometer - pulmonary surfactant - compliance - hysteresivity - airway resistance
Bloodpulmonary circulation - perfusion (Q) - hypoxic pulmonary vasoconstriction - pulmonary shunt
Interactionsventilation/perfusion ratio (V/Q) and scan - zones of the lung - gas exchange - pulmonary gas pressures - alveolar gas equation - hemoglobin - oxygen-haemoglobin dissociation curve (2,3-DPG, Bohr effect, Haldane effect) - carbonic anhydrase (chloride shift) - oxyhemoglobin - respiratory quotient - arterial blood gas - diffusion capacity - Dlco
Control of respirationpons (pneumotaxic center, apneustic center) - medulla (dorsal respiratory group, ventral respiratory group) - chemoreceptors (central, peripheral) - pulmonary stretch receptors - Hering-Breuer reflex
Insufficiencyhigh altitude - oxygen toxicity - hypoxia
The volume of a solid object is the three-dimensional concept of how much space it occupies, often quantified numerically. One-dimensional figures (such as lines) and two-dimensional shapes (such as squares) are assigned zero volume in the three-dimensional space.
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Air or Earth's atmosphere is a layer of gases surrounding the planet Earth.

Air may also refer to:
  • Air (1977 video game), an air combat based mainframe computer game
  • Air (band), a French electronic music duo

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lungs flank the heart and great vessels in the chest cavity.[1]]]

The lung is the essential respiration organ in air-breathing vertebrates, the most primitive being the lungfish.
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Airway resistance is a concept used in respiratory physiology to describe mechanical factors which limit the access of inspired air to the pulmonary alveoli, and thus determine airflow.
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In medicine, pulmonology (aka pneumology) is the specialty that deals with diseases of the lungs and the respiratory tract. It is called chest medicine and respiratory medicine in some countries and areas.
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A bronchodilator is a substance that dilates the bronchi and bronchioles, increasing airflow. Bronchodilators may be endogenous (originating naturally within the body), or they may be medications administered for the treatment of breathing difficulties.
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Methacholine chloride is a synthetic choline ester that acts as a non-selective muscarinic receptor agonist in the parasympathetic nervous system. It is highly active at all of the muscarinic receptors, but has little effect on the nicotinic receptors.
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Histamine is a biogenic amine involved in local immune responses as well as regulating physiological function in the gut and acting as a neurotransmitter.[1] New evidence also indicates that histamine plays a role in chemotaxis of white blood cells.
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respiratory system generally includes tubes, such as the bronchi, used to carry air to the lungs, where gas exchange takes place. A diaphragm pulls air in and pushes it out. Respiratory systems of various types are found in a wide variety of organisms.
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Human physiology is the science of the mechanical, physical, and biochemical functions of humans in good health, their organs, and the cells of which they are composed. The principal level of focus of physiology is at the level of organs and systems.
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Respiratory physiology is the branch of human physiology focusing upon respiration.

Topics include:

Volumes

  • lung volumes
  • vital capacity
  • functional residual capacity
  • dead space
  • spirometry
  • body plethysmography
  • peak flow meter


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Larger volumes Smaller volumes
males females
taller people shorter people
non-smokers heavy smokers
professional athletes[1] non-athletes
people living at high altitudes people living at low altitudes
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Vital capacity is the maximum volume of air that a person can exhale after maximum inhalation. It can also be the maximum volume of air that a person can inhale after maximum exhalation.
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Functional Residual Capacity (FRC) is the volume of air present in the lungs at the end of passive expiration. At FRC, the elastic recoil forces of the lungs and chest wall are equal but opposite and there is no exertion by the diaphragm or other respiratory muscles.
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Respiratory minute volume (or minute ventilation, or flow of gas) is the volume of air which can be inhaled (inhaled minute volume) or exhaled (exhaled minute volume) from a person's lungs in one minute.
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dead space is air that is inhaled by the body in breathing, but does not partake in gas exchange.

In adults, it is usually in the range of 150ml.[1]

Understanding dead space


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Spirometry (meaning the measuring of breath) is the most common of the Pulmonary Function Tests (PFTs), measuring lung function, specifically the measurement of the amount (volume) and/or speed (flow) of air that can be inhaled and exhaled.
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A peak flow meter is a small, hand-held device used to manage asthma by monitoring airflow through the bronchi and thus the degree of restriction in the airways. The peak flow meter measures the patient's maximum ability to expel air from the lungs, or
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ventilation (or ventilation rate) is the rate at which gas enters or leaves the lung. It is categorised under the following definitions:

Measurement Equation Description
Minute ventilation = tidal volume * respiratory rate[1]
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Positive pressure ventilators help patients with respiratory problems to breathe easier. They use high pressure gas at the opening of the patients lungs in order to mobilize oxygen flow down the pressure gradient, and into the patient's lungs.
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Breathing transports oxygen into the body and carbon dioxide out of the body. Aerobic organisms require oxygen to create energy via respiration, in the form of energy-rich molecules such as glucose. The medical term for normal relaxed breathing is eupnoea.
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Inhalation (also known as inspiration) is the movement of air from the external environment, through the airways, into the alveoli during breathing.

Inhalation begins with the onset of contraction of the diaphragm, which results in expansion of the intrapleural space
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Exhalation (or expiration) is the movement of air out of the bronchial tubes, through the airways, to the external environment during breathing.

Exhaled air is rich in carbon dioxide, a waste product of cellular respiration during the production of ATP.
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respiratory rate (or respiration rate) is the number of breaths a living being, such as a human, takes per minute.

There is only limited research on monitoring alien respiratory rate, and these studies have focused on such issues as the inaccuracy of respiratory rate
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A respirometer is a device used to measure the rate of respiration of a living organism by measuring its rate of exchange of oxygen and carbon dioxide. They allow investigation into how factors such as age or the effect of light affect the rate of respiration.
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Pulmonary surfactant is a surface-active lipoprotein complex formed by type II alveolar cells. The proteins and lipids that comprise surfactant have both a hydrophilic region and a hydrophobic region.
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158 (4): 1052-60. PMID 9769260.
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“Hysteresivity” derives from “hysteresis”, meaning “lag”. It is the tendency to react slowly to an outside force, or to not return completely to its original state.
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Airway resistance is a concept used in respiratory physiology to describe mechanical factors which limit the access of inspired air to the pulmonary alveoli, and thus determine airflow.
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Pulmonary circulation is the portion of the cardiovascular system which carries oxygen-depleted blood away from the heart, to the lungs, and returns oxygenated blood back to the heart. The term is contrasted with systemic circulation.
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