| Anaesthesia and the respiratory system. | |
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MedLine Citation:
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PMID: 393367 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Pulmonary gas exchange is disturbed during general anaesthesia; both oxygenation and elimination of carbon dioxide are impaired. The shape of the chest wall alters after induction of anaesthesia-paralysis in recumbent subjects, and its motion during inspiration is also altered. The mechanical properties of lung and chest wall are also affected and FRC may be reduced. Inspired gas distribution changes after induction of anaesthesia-paralysis with mechanical ventilation of the lungs. Distribution of pulmonary blood flow is altered in subjects in the sitting and right lateral decubitus positions, but the distribution is not adjusted to the altered distribution of inspired gas. This results in an increased mismatching of ventilation to perfusion, with development of lung regions that have low and high ventilation-to-perfusion ratios. Some lung regions with low ventilation-to-perfusion ratios develop into right-to-left shunt on breathing 100 per cent oxygen. The following sequence of events probably occurs after induction of anaesthesia-paralysis. The initial effect of anaesthesia seems to be on the shape and motion of the chest wall. This may alter the mechanical properties of both the chest wall and the lung. Intrapulmonary gas distribution is altered secondarily. Pulmonary bloodflow distribution, which is primarily determined by gravity, does not seem to adjust to the altered distribution of inspired gas. Hence, an increased mismatching of ventilation to perfusion develops. This includes the development of lung regions with low ventilation-to-perfusion ratios. These regions may progress into right-to-left shung during 100 per cent oxygen breathing. The low ventilation-to-perfusion regions and the shunt may both impair oxygenation. The development of lung regions with high ventilation-to-perfusion ratios after induction of anaesthesia-paralysis contributes to the inefficient elimination of carbon dioxide. |
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Authors:
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K Rehder |
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Publication Detail:
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Type: Journal Article; Research Support, U.S. Gov't, P.H.S.; Review |
Journal Detail:
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Title: Canadian Anaesthetists' Society journal Volume: 26 ISSN: 0008-2856 ISO Abbreviation: Can Anaesth Soc J Publication Date: 1979 Nov |
Date Detail:
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Created Date: 1980-04-25 Completed Date: 1980-04-25 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0371163 Medline TA: Can Anaesth Soc J Country: CANADA |
Other Details:
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Languages: eng Pagination: 451-62 Citation Subset: IM |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Anesthesia, General* Animals Functional Residual Capacity Humans Lung / drug effects Lung Compliance / drug effects Lung Volume Measurements Muscles / drug effects Nitrogen / physiology Oxygen / physiology Pressure Respiration / drug effects* Respiration, Artificial Ventilation-Perfusion Ratio |
| Chemical | |
Reg. No./Substance:
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7727-37-9/Nitrogen; 7782-44-7/Oxygen |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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