Resuscitation of hemorrhagic shock with normal saline vs. lactated Ringer's: effects on oxygenation, extravascular lung water, and hemodynamics
Critical Care 2009, 13:R30doi:10.1186/cc7736
Pulmonary edema and impairment of oxygenation are reported as common consequences of hemorrhagic shock and resuscitation (HSR). Surprisingly, there is little in the literature examining differences in crystalloid type during the early phase of HSR regarding the development of pulmonary edema, the impact on oxygenation and the hemodynamic response. These experiments were designed to determine if differences exist due to crystalloid fluid type in the development of edema, the impact on oxygenation and the hemodynamic response to fluid administration in early HSR.
20 anesthetized swine underwent a grade V liver injury and bled without resuscitation for 30 minutes. The animals were randomized to receive, in a blinded fashion, either normal saline (NS) (n=10) or lactated Ringer's (LR) (n=10). They were then resuscitated with study fluid to, and maintained at, the preinjury mean arterial pressure (MAP) for 90 minutes.
Extravascular lung water index (EVLWI) began to increase immediately with resuscitation with both fluid types, increasing earlier and to a greater degree with NS. A 1ml/kg increase in EVLWI from baseline occurred after (mean +/- SEM) 68.6 ml/kg +/- 5.2 ml/kg of normal saline and 81.3 ml/kg +/- 8.7 ml/kg of LR (p=0.027). After 150 ml/kg of fluid EVLWI increased from 9.5 +/- 0.3 to 11.4 +/- 0.3 ml/kg NS and from 9.3 +/- 0.2 to 10.8 +/- 0.3 ml/kg (p = 0.035) LR. Despite this, oxygenation was not significantly impacted (DeltaPaO2/FiO2 [greater than or equal to]100) until approximately 250 ml/kg of either fluid had been administered. Animals resuscitated with NS were more acidemic (with lower lactates), pH 7.17 +/- 0.03 NS vs. 7.41 +/- 0.02 LR, p< 0.001.
This study suggests that early resuscitation of hemorrhagic shock with NS or LR has little impact on oxygenation when resuscitation volume is less than 250 ml/kg. LR has more favorable effects than NS on EVLWI, pH, and blood pressure but not on oxygenation.