• J Clin Monit Comput · Jan 2000

    Review

    Atelectasis formation during anesthesia: causes and measures to prevent it.

    • G Hedenstierna and H U Rothen.
    • Department of Clinical Physiology, University Hospital, Uppsala, Sweden. goran.hedenstierna@klinfys.uu.se
    • J Clin Monit Comput. 2000 Jan 1; 16 (5-6): 329-35.

    AbstractPulmonary gas exchange is regularly impaired during general anaesthesia with mechanical ventilation. This results in decreased oxygenation of blood. A major cause is collapse of lung tissue (atelectasis), which can be demonstrated by computed tomography but not by conventional chest x-ray. Collapsed lung tissue is present in 90% of all subjects, both during spontaneous breathing and after muscle paralysis, and whether intravenous or inhalational anaesthetics are used. There is a correlation between the amount of atelectasis and pulmonary shunt. Shunt does not increase with age. In obese patients, larger atelectatic areas are present than in lean ones. Finally, patients with chronic obstructive lung disease may show less or even no atelectasis. There are different procedures that can be used in order to prevent atelectasis or to reopen collapsed lung tissue. The application of positive end-expiratory pressure (PEEP) has been tested in several studies. On the average, arterial oxygenation does not improve markedly, and atelectasis may persist. Further, reopened lung units re-collapse rapidly after discontinuation of PEEP. Inflation of the lungs to an airway pressure of 40 cm H2O, maintained for 7-8 seconds (recruitment or "vital capacity" manoeuvre), re-expands all previously collapsed lung tissue. During induction of anaesthesia, the use of a gas mixture, that includes a poorly absorbed gas such as nitrogen, may prevent the early formation of atelectasis. During ongoing anaesthesia, pulmonary collapse reappears slowly if a low fraction of oxygen in nitrogen is used for the ventilation of the lungs after a previous VC-manoeuvre. On the other hand, ventilation of the lungs with pure oxygen results in a rapid reappearance of atelectasis. Thus, ventilation during anaesthesia should be done if possible with a moderate fraction of inspired oxygen (FIO2, e.g. 0.3-0.4). Alternatively, if the lungs are ventilated with a high inspiratory fraction of oxygen, the use of PEEP may be considered. In summary, atelectasis is present in most humans during anaesthesia and is a major cause of impaired oxygenation. Avoiding high fractions of oxygen in inspired gas during induction and maintenance of anaesthesia may prevent formation of atelectasis. Finally, intermittent "vital capacity"-manoeuvres together with PEEP reduces the amount of atelectasis and pulmonary shunt.

      Pubmed     Copy Citation     Plaintext  

      Add institutional full text...

    Notes

     
    Knowledge, pearl, summary or comment to share?
    300 characters remaining
    help        
    You can also include formatting, links, images and footnotes in your notes
    • Simple formatting can be added to notes, such as *italics*, _underline_ or **bold**.
    • Superscript can be denoted by <sup>text</sup> and subscript <sub>text</sub>.
    • Numbered or bulleted lists can be created using either numbered lines 1. 2. 3., hyphens - or asterisks *.
    • Links can be included with: [my link to pubmed](http://pubmed.com)
    • Images can be included with: ![alt text](https://bestmedicaljournal.com/study_graph.jpg "Image Title Text")
    • For footnotes use [^1](This is a footnote.) inline.
    • Or use an inline reference [^1] to refer to a longer footnote elseweher in the document [^1]: This is a long footnote..

    hide…

What will the 'Medical Journal of You' look like?

Start your free 21 day trial now.

We guarantee your privacy. Your email address will not be shared.