Small volume 7.5% NaCl with 6% Dextran-70 or 6% and 10% hetastarch are associated with arrhythmias and death after 60 minutes of severe hemorrhagic shock in the rat in vivo.

Abstract

BACKGROUND:

Hypertonic saline solutions in combination with colloids may have some applications in critically ill patients. Our aim was to examine the effects of small volumes (0.7-1 mL/kg intravenous) of 7.5% NaCl with different colloids on cardiac stability, hemodynamics, and mortality after severe hemorrhagic shock.

METHODS:

Male fed Sprague-Dawley rats (300-450 g, n = 48) were anesthetized and randomly assigned to one of six groups: (1) untreated (bleed only), (2) 7.5% NaCl, (3) 7.5% NaCl/6% dextran-70, (4) 7.5% NaCl/6% hetastarch (HES), (5) 6% HES alone, and (6) 7.5% NaCl/10% HES. Hemorrhagic shock was induced by phlebotomy until the mean arterial pressure (MAP) was 35 mm Hg to 40 mm Hg and continued for 20 minutes until ∼40% blood loss. Animals were left in shock for 60 minutes at 34°C. 0.3 mL (<4% of shed blood) was injected as a 10 seconds bolus into the femoral vein. Lead II electrocardiogram, blood pressures, MAP, and heart rate were monitored.

RESULTS:

Untreated rats were highly arrhythmogenic with 38% mortality. 7.5% NaCl increased MAP from 39 mm Hg to 44 mm Hg with no severe arrhythmias or mortality. Dextran-70 increased MAP from 38 mm Hg to 49 mm Hg, transiently increased QRS amplitude (1.5 times) and was arrhythmogenic affecting 50% of animals with no deaths. Addition of 6% HES to hypertonic saline resulted in aberrant arrhythmias and 38% mortality. Six percent HES alone was proarrhythmic and led to 38% mortality. 7.5% NaCl with 10% HES resulted in 100% mortality (p < 0.05) from arrhythmias within 5 minutes of resuscitation.

CONCLUSIONS:

Small volumes of 7.5% NaCl led to fewer arrhythmias and a 2.6 times survival benefit over untreated rats, and a partial resuscitation of MAP into the "permissive range." Dextran-70 or HES in 7.5% NaCl were proarrhythmic and HES led to increased mortality (p < 0.05). Because optimal heart function is critical for successful resuscitation, care should be exercised when using dextran-70 or 6 and 10% HES in small volume hypertonic saline solutions for early hypotensive resuscitation.

• Authors: Hayley L Letson, Geoffrey P Dobson
• Journal: The Journal of trauma (J Trauma) Vol. 70 Issue 6 Pg. 1444-52 (Jun 2011) ISSN: 1529-8809 [Electronic] United States
• PMID: 20805759 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Dextrans
• Hydroxyethyl Starch Derivatives
• Saline Solution, Hypertonic

Topics

• Analysis of Variance
• Animals
• Arrhythmias, Cardiac (mortality, physiopathology)
• Dextrans (administration & dosage, pharmacology)
• Disease Models, Animal
• Fluid Therapy (adverse effects, methods)
• Hemodynamics
• Hydroxyethyl Starch Derivatives (administration & dosage, pharmacology)
• Male
• Random Allocation
• Rats
• Rats, Sprague-Dawley
• Saline Solution, Hypertonic (administration & dosage, pharmacology)
• Shock, Hemorrhagic (mortality, physiopathology, therapy)
• Statistics, Nonparametric
• Survival Rate