Large volume crystalloid resuscitation does not increase extravascular lung water.

Area of Science:

• Critical Care Medicine
• Physiology
• Resuscitation Science

Background:

• Hemorrhagic shock necessitates fluid resuscitation.
• The impact of crystalloid solutions on lung water during resuscitation is a critical concern.
• Understanding fluid dynamics in shock is vital for patient outcomes.

Purpose of the Study:

• To investigate if Ringer's lactate solution elevates extravascular lung water (EVLW) during resuscitation following hemorrhagic shock.
• To assess the effects of crystalloid resuscitation on lung fluid balance.

Main Methods:

• Ten anesthetized sheep underwent induced hemorrhagic shock, maintaining a mean arterial pressure (MAP) of 50 mm Hg.
• Resuscitation utilized Ringer's lactate to restore MAP, pulmonary capillary wedge pressure (PCWP), and cardiac index to pre-bleeding levels.
• Measurements included colloid oncotic pressure (COP) and EVLW before and after resuscitation.

Main Results:

• Despite significant decreases in the colloid oncotic pressure (COP) - PCWP gradient and COP itself, extravascular lung water (EVLW) did not increase.
• The COP - PCWP gradient decreased from 12 +/- 3 to 2 +/- 5 mm Hg (P < 0.001).
• COP decreased from 19 +/- 8 to 12 +/- 2 mm Hg (P < 0.001).

Conclusions:

• Crystalloid resuscitation, specifically with Ringer's lactate, does not invariably lead to increased extravascular lung water (EVLW).
• This finding challenges the assumption that reduced oncotic pressure gradients automatically result in pulmonary edema during resuscitation.
• Ringer's lactate can be a safe resuscitation fluid in hemorrhagic shock, even with significant hemodynamic and oncotic shifts.