Cardiac arrest patients have an impaired immune response, which is not influenced by induced hypothermia.

Abstract

INTRODUCTION:

Induced hypothermia is increasingly applied as a therapeutic intervention in ICUs. One of the underlying mechanisms of the beneficial effects of hypothermia is proposed to be reduction of the inflammatory response. However, a fear of reducing the inflammatory response is an increased infection risk. Therefore, we studied the effect of induced hypothermia on immune response after cardiac arrest.

METHODS:

A prospective observational cohort study in a mixed surgical-medical ICU. Patients admitted at the ICU after surviving cardiac arrest were included and during 24 hours body temperature was strictly regulated at 33°C or 36°C. Blood was drawn at three time points: after reaching target temperature, at the end of the target temperature protocol and after rewarming to 37°C. Plasma cytokine levels and response of blood leucocytes to stimulation with toll-like receptor (TLR) ligands lipopolysaccharide (LPS) from Gram-negative bacteria and lipoteicoic acid (LTA) from Gram-positive bacteria were measured. Also, monocyte HLA-DR expression was determined.

RESULTS:

In total, 20 patients were enrolled in the study. Compared to healthy controls, cardiac arrest patients kept at 36°C (n = 9) had increased plasma cytokines levels, which was not apparent in patients kept at 33°C (n = 11). Immune response to TLR ligands in patients after cardiac arrest was generally reduced and associated with lower HLA-DR expression. Patients kept at 33°C had preserved ability of immune cells to respond to LPS and LTA compared to patients kept at 36°C. These differences disappeared over time. HLA-DR expression did not differ between 33°C and 36°C.

CONCLUSIONS:

Patients after cardiac arrest have a modest systemic inflammatory response compared to healthy controls, associated with lower HLA-DR expression and attenuated immune response to Gram-negative and Gram-positive antigens, the latter indicative of an impaired immune response to bacteria. Patients with a body temperature of 33°C did not differ from patients with a body temperature of 36°C, suggesting induced hypothermia does not affect immune response in patients with cardiac arrest.

TRIAL REGISTRATION:

ClinicalTrials.gov NCT01020916, registered 25 November 2009.

• Authors: Charlotte J Beurskens, Janneke Horn, Anita M Tuip de Boer, Marcus J Schultz, Ester Mm van Leeuwen, Margreeth B Vroom, Nicole P Juffermans
• Journal: Critical care (London, England) (Crit Care) Vol. 18 Issue 4 Pg. R162 (Jul 30 2014) ISSN: 1466-609X [Electronic] England
• PMID: 25078879 (Publication Type: Controlled Clinical Trial, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Cytokines
• Lipopolysaccharides
• Toll-Like Receptors

Topics

• Analysis of Variance
• Body Temperature (immunology)
• Cytokines (blood, immunology)
• Female
• Glasgow Coma Scale
• Heart Arrest (immunology, therapy)
• Humans
• Hypothermia, Induced (adverse effects, methods)
• Inflammation (immunology)
• Intensive Care Units
• Leukocytes (immunology)
• Lipopolysaccharides (blood, immunology)
• Male
• Middle Aged
• Netherlands
• Prospective Studies
• Toll-Like Receptors (blood, immunology)