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either of two saclike respiratory organs in the chest of vertebrates; serves to remove carbon dioxide and provide oxygen to the blood

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《しばしば複数形で》『肺』,肺臓
(要求・命令などへの)承諾,応諾 / 服従,盲従

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/11/07 16:52:24」(JST)

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Pulmonary compliance (or lung compliance) is a measure of the lung's ability to stretch and expand. In clinical practice it is separated into two different measurements, static compliance and dynamic compliance. Static lung compliance is the change in volume for any given applied pressure.^[1] Dynamic lung compliance is the compliance of the lung at any given time during actual movement of air.

Low compliance indicates a stiff lung (one with high elastic recoil) and can be thought of as a thick balloon - this is the case often seen in fibrosis. High compliance indicates a pliable lung (one with low elastic recoil) and can be thought of as a grocery bag - this is the case often seen in emphysema. Compliance is highest at moderate lung volumes, and much lower at volumes which are very low or very high. The compliance of the lungs demonstrate hysteresis; that is, the compliance is different on inspiration and expiration for identical volumes.

Calculation

Pulmonary compliance is calculated using the following equation, where ΔV is the change in volume, and ΔP is the change in pleural pressure:

For example, if a patient inhales 500 mL of air from a spirometer with an intrapleural pressure before inspiration of – 5 cm H₂O and -10 cm H₂O at the end of inspiration. Then:

Static compliance (C_stat)

Static compliance represents pulmonary compliance during periods without gas flow, such as during an inspiratory pause. It can be calculated with the formula:

where P_plat = plateau pressure. P_plat is measured at the end of inhalation and prior to exhalation using an inspiratory hold maneuver. During this maneuver, airflow is transiently (~0.5 sec) discontinued, which eliminates the effects of airway resistance. Pplat is never > PIP and is typically < 3-5 cmH2O lower than PIP when airway resistance is not elevated.

Dynamic compliance (C_dyn)

Dynamic compliance represents pulmonary compliance during periods of gas flow, such as during active inspiration. Dynamic compliance is always less than or equal to static lung compliance. It can be calculated using the following equation, where C_dyn = Dynamic compliance; V_T = tidal volume; PIP = Peak inspiratory pressure (the maximum pressure during inspiration); PEEP = Positive End Expiratory Pressure:

Alterations in airway resistance, lung compliance and chest wall compliance influence C_dyn.

Clinical significance

It is in fact an important measurement in respiratory physiology.^[2]^[3]^[4]

fibrosis is associated with a decrease in pulmonary compliance.
emphysema/COPD may be associated with an increase in pulmonary compliance due to the loss of alveolar and elastic tissue.

Pulmonary surfactant increases compliance by decreasing the surface tension of water. The internal surface of the alveolus is covered with a thin coat of fluid. The water in this fluid has a high surface tension, and provides a force that could collapse the alveolus. The presence of surfactant in this fluid breaks up the surface tension of water, making it less likely that the alveolus can collapse inward. If the alveolus were to collapse, a great force would be required to open it, meaning that compliance would decrease drastically.

Functional significance of abnormally high or low compliance

Low compliance indicates a stiff lung and means extra work is required to bring in a normal volume of air. This occurs as the lungs in this case become fibrotic, lose their distensibility and become stiffer.

In a highly compliant lung, as in emphysema, the elastic tissue is damaged by enzymes. These enzymes are secreted by leukocytes (white blood cells) in response to a variety of inhaled irritants, such as cigarette smoke. Patients with emphysema have a very high lung compliance due to the poor elastic recoil, they have no problem inflating the lungs but have extreme difficulty exhaling air. In this condition extra work is required to get air out of the lungs. Compliance also increases with increasing age.

Compliance decreases in the following cases:

Supine position
Laparoscopic surgical interventions
Severe restrictive pathologies
Chronic restrictive pathologies
Hydrothorax
Pneumothorax
High standing of a diaphragm
Acute asthma attacks [Increased compliance also occurs,for an unclear reason^[5]]

References

^ Lung compliance at the US National Library of Medicine Medical Subject Headings (MeSH)
^ Compliance
^ Nikischin W, Gerhardt T, Everett R, Bancalari E (1998). "A new method to analyze lung compliance when pressure-volume relationship is nonlinear.". Am J Respir Crit Care Med 158 (4): 1052–60. doi:10.1164/ajrccm.158.4.9801011. PMID 9769260. article
^ Physiology: 4/4ch2/s4ch2_21 - Essentials of Human Physiology
^ J.B.West, Respiratory Physiology, 9th edition,page 99

UpToDate Contents

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1. 機械的人工換気の概要 overview of mechanical ventilation
2. 機械的人工換気の生理学的および病理生理学的転帰 physiologic and pathophysiologic consequences of mechanical ventilation
3. 急性呼吸窮迫症候群：成人における疫学、病態生理、病理、および病因 acute respiratory distress syndrome epidemiology pathophysiology pathology and etiology in adults
4. 成人の急性呼吸窮迫症候群における機械的人工換気 mechanical ventilation of adults in acute respiratory distress syndrome
5. 神経筋障害および胸壁障害のある患者における睡眠の影響 the effect of sleep in patients with neuromuscular and chest wall disorders

English Journal

Randomised comparison of two neonatal resuscitation bags in manikin ventilation.

Thallinger M1, Ersdal HL2, Ombay C3, Eilevstjønn J4, Størdal K5.
Archives of disease in childhood. Fetal and neonatal edition.Arch Dis Child Fetal Neonatal Ed.2015 Oct 5. pii: fetalneonatal-2015-308754. doi: 10.1136/archdischild-2015-308754. [Epub ahead of print]
OBJECTIVE: To compare ventilation properties and user preference of a new upright neonatal resuscitator developed for easier cleaning, reduced complexity, and possibly improved ventilation properties, with the standard Laerdal neonatal resuscitator.DESIGN: Eighty-seven Tanzanian and Norwegian nursin
PMID 26437670

High PEEP levels are associated with overdistension and tidal recruitment/derecruitment in ARDS patients.

Retamal J1,2, Bugedo G1, Larsson A2, Bruhn A1.
Acta anaesthesiologica Scandinavica.Acta Anaesthesiol Scand.2015 Oct;59(9):1161-9. doi: 10.1111/aas.12563. Epub 2015 Jun 10.
BACKGROUND: Positive end-expiratory pressure (PEEP) improves gas exchange and respiratory mechanics, and it may decrease tissue injury and inflammation. The mechanisms of this protective effect are not fully elucidated. Our aim was to determine the intrinsic effects of moderate and higher levels of
PMID 26061818

Caregiver treatment satisfaction is improved together with children's asthma control: Prospective study for budesonide monotherapy in school-aged children with uncontrolled asthma symptoms.

Yoshihara S1, Kanno N2, Fukuda H3, Arisaka O3, Arita M4, Sekine K5, Yamaguchi K6, Tsuchida A7, Yamada Y8, Watanabe T9, Shimizu T10, Nishikawa K11, Nishimuta T12.
Allergology international : official journal of the Japanese Society of Allergology.Allergol Int.2015 Oct;64(4):371-6. doi: 10.1016/j.alit.2015.05.010. Epub 2015 Jul 10.
BACKGROUND: If asthmatic children cannot obtain sufficient control of their disease, not only do they suffer from asthma symptoms, but the daily life activities of their caregivers are also disrupted. We investigated the effectiveness of an inhaled corticosteroid (ICS) for symptom control in previou
PMID 26433534

Japanese Journal

Protective Effect of Surfactant Inhalation against Warm Ischemic Injury in an Isolated Rat Lung Ventilation Model.

Ohsumi Akihiro,Chen Fengshi,Sakamoto Jin,Nakajima Daisuke,Kobayashi Masashi,Bando Toru,Date Hiroshi
PloS one 8(8), 2013-08-29
… This study investigated the mechanisms of surfactant inhalation protection of the warm ischemic lung after reoxygenation with ventilation alone. … In an isolated rat lung ventilation model, cardiac arrest was induced in the CTRL (control) and SURF (surfactant treatment) groups by ventricular fibrillation. … the lungs were flushed, and a heart and lung block was procured. …
NAID 120005324900

Limited resection and two-staged lobectomy for non-small cell lung cancer with ground-glass opacity

Ohtaka Kazuto,Hida Yasuhiro,Kaga Kichizo,Kato Tatsuya,Muto Jun,Nakada-Kubota Reiko,Hirano Satoshi,Matsui Yoshiro
Journal of Cardiothoracic Surgery 8, 2013-04-24
… Background: Lung tumors showing ground-glass opacities on high-resolution computed tomography indicate the presence of inflammation, atypical adenomatous hyperplasia, or localized bronchioloalveolar carcinoma. … However, low compliance for and invasiveness of the second surgery are concerns associated with this strategy. …
NAID 120005297916

Protective effect of pre-recovery surfactant inhalation on lungs donated after cardiac death in a canine lung transplantation model.

Ohsumi Akihiro,Chen Fengshi,Sakamoto Jin,Nakajima Daisuke,Hijiya Kyoko,Motoyama Hideki,Okita Kenji,Horita Kenta,Kikuchi Ryutaro,Yamada Tetsu,Bando Toru,Date Hiroshi
The Journal of heart and lung
… The lungs were flushed and procured, and the left lung was transplanted into recipient dogs. … At 45 minutes of reperfusion, the right pulmonary artery was ligated, and the left transplanted lung function was evaluated. … The SF group showed significantly better dynamic compliance, oxygenation, and wet-to-dry weight ratio. …
NAID 120004874000