Show Summary Details
Page of

Crystalloids in critical illness 

Crystalloids in critical illness
Crystalloids in critical illness

Karthik Raghunathan

and Andrew Shaw

Page of

PRINTED FROM OXFORD MEDICINE ONLINE ( © Oxford University Press, 2022. All Rights Reserved. Under the terms of the licence agreement, an individual user may print out a PDF of a single chapter of a title in Oxford Medicine Online for personal use (for details see Privacy Policy and Legal Notice).

date: 18 May 2022

‘Crystalloid’ refers to solutions of crystalline substances that can pass through a semipermeable membrane and are distributed widely in body fluid compartments. The conventional Starling model predicts transvascular exchange based on the net balance of opposing hydrostatic and oncotic forces. Based on this model, colloids might be considered superior resuscitative fluids. However, observations of fluid behaviour during critical illness are not consistent with such predictions. Large randomized controlled studies have consistently found that colloids offer no survival advantage relative to crystalloids in critically-ill patients. A revised Starling model describes a central role for the endothelial glycocalyx in determining fluid disposition. This model supports crystalloid utilization in most critical care settings where the endothelial surface layer is disrupted and lower capillary pressures (hypovolaemia) make volume expansion with crystalloids effective, since transvascular filtration decreases, intravascular retention increases and clearance is significantly reduced. There are important negative consequences of both inadequate and excessive crystalloid resuscitation. Precise dosing may be titrated based on functional measures of preload responsiveness like pulse pressure variation or responses to manoeuvres such as passive leg raising. Crystalloids have variable electrolyte concentrations, volumes of distribution, and, consequently variable effects on plasma pH. Choosing balanced crystalloid solutions for resuscitation may be potentially advantageous versus ‘normal’ (isotonic, 0.9%) saline solutions. When used as the primary fluid for resuscitation, saline solutions may have adverse effects in critically-ill patients secondary to a reduction in the strong ion difference and hyperchloraemic, metabolic acidosis. Significant negative effects on immune and renal function may result as well.

Access to the complete content on Oxford Medicine Online requires a subscription or purchase. Public users are able to search the site and view the abstracts for each book and chapter without a subscription.

Please subscribe or login to access full text content.

If you have purchased a print title that contains an access token, please see the token for information about how to register your code.

For questions on access or troubleshooting, please check our FAQs, and if you can't find the answer there, please contact us.