• Respiratory care · Oct 2014

    Review

    Carbon dioxide in the critically ill: too much or too little of a good thing?

    • Jonathan Marhong and Eddy Fan.
    • Interdepartmental Division of Critical Care Medicine, University of Toronto and the Department of Medicine, University Health Network and Mount Sinai Hospital, Toronto, Ontario, Canada.
    • Respir Care. 2014 Oct 1;59(10):1597-605.

    AbstractHypercapnia and hypocapnia commonly complicate conditions that are present in critically ill patients. Both conditions have important physiologic effects that may impact the clinical management of these patients. For instance, hypercapnia results in bronchodilation and enhanced hypoxic vasoconstriction, leading to improved ventilation/perfusion matching. Hypocapnia reduces cerebral blood volume through arterial vasoconstriction. These effects have also been exploited for therapeutic aims. In patients with traumatic brain injury (TBI), hypocapnia is often utilized to control intracranial pressure. However, this effect is not sustained, and prolonged hypocapnia increases the risk of mortality and severe disability in patients with TBI. Hypercapnia and hypercapnic acidosis are common consequences of lung-protective ventilation in ARDS. Hypercapnic acidosis reduces ischemic lung injury and preserves lung compliance, but concern has arisen over hypercapnia-induced immunosuppression and the potential for bacterial proliferation in sepsis. Experimental studies suggest that buffering hypercapnic acidosis attenuates these effects, whereas hypocapnia appears to potentiate lung injury through increased capillary permeability and decreased lung compliance. Several areas of uncertainty surround the role of hypercapnia/hypocapnia in treating TBI and ARDS. Current data support recommendations to avoid hypocapnia in treating TBI, with the exception of emergent treatment of elevated intracranial pressure, while awaiting definitive management. Permissive hypercapnia is commonly accepted as a consequence of lung-protective ventilation in ARDS, but there is insufficient evidence to support the induction of hypercapnic acidosis in clinical practice. Buffering hypercapnic acidosis should be considered only for a specific clinical indication (eg, hemodynamic instability). For clinicians choosing to buffer hypercapnic acidosis, tris-hydroxymethyl aminomethane is recommended over sodium bicarbonate, as it is more effective in correcting pH and is not associated with increased carbon dioxide production. Future studies should aim to address these areas of uncertainty to help guide clinicians in the therapeutic use and management of hypercapnia/hypocapnia in critically ill patients.Copyright © 2014 by Daedalus Enterprises.

      Pubmed     Free full text   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…