title: Resuscitation of haemorrhagic shock with normal saline vs. lactated Ringer's: effects on oxygenation, extravascular lung water and haemodynamics.
abstract: BACKGROUND
  Pulmonary oedema and impairment of oxygenation are reported as common consequences of haemorrhagic shock and resuscitation (HSR). Surprisingly, there is little information in the literature examining differences in crystalloid type during the early phase of HSR regarding the development of pulmonary oedema, the impact on oxygenation and the haemodynamic response. These experiments were designed to determine if differences exist because of crystalloid fluid type in the development of oedema, the impact on oxygenation and the haemodynamic response to fluid administration in early HSR.
  
  
  METHODS
  Twenty anaesthetised swine underwent a grade V liver injury and bled without resuscitation for 30 minutes. The animals were randomised to receive, in a blinded fashion, either normal saline (NS; n = 10) or lactated Ringer's solution (LR; n = 10). They were then resuscitated with study fluid to, and maintained at, the preinjury mean arterial pressure (MAP) for 90 minutes.
  
  
  RESULTS
  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 1 ml/kg increase in EVLWI from baseline occurred after administartion of (mean +/- standard error of the mean) 68.6 +/- 5.2 ml/kg of normal saline and 81.3 +/- 8.7 ml/kg of LR (P = 0.027). After 150 ml/kg of fluid, EVLWI increased from 9.5 +/- 0.3 ml/kg to 11.4 +/- 0.3 ml/kg NS and from 9.3 +/- 0.2 ml/kg to 10.8 +/- 0.3 ml/kg LR (P = 0.035). Despite this, oxygenation was not significantly impacted (Delta partial pressure of arterial oxygen (PaO2)/fraction of inspired oxygen (FiO2) <or= 100) until approximately 250 ml/kg of either fluid had been administered. Animals resuscitated with NS were more acidaemic (with lower lactates), pH 7.17 +/- 0.03 NS vs. 7.41 +/- 0.02 LR (P < 0.001).
  
  
  CONCLUSIONS
  This study suggests that early resuscitation of haemorrhagic shock with NS or LR has little impact on oxygenation when resuscitation volume is less than 250 ml/kg. LR has more favourable effects than NS on EVLWI, pH and blood pressure but not on oxygenation.
authors.affiliation: Department of Medicine, Division of Pulmonary and Critical Care Medicine, Oregon Health and Science University, Physicians Pavilion, Suite 340, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA. phillipc@ohsu.edu
authors.forename: Charles R
authors.initials: CR
authors.lastname: Phillips
authors.forename: Kevin
authors.initials: K
authors.lastname: Vinecore
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Hagg
authors.forename: Rebecca S
authors.initials: RS
authors.lastname: Sawai
authors.forename: Jerome A
authors.initials: JA
authors.lastname: Differding
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Watters
authors.forename: Martin A
authors.initials: MA
authors.lastname: Schreiber
mesh_terms: D000818:Animals; D015633:Extravascular Lung Water / Q000187:drug effects*; D006439:Hemodynamics / Q000187:drug effects*; D007552:Isotonic Solutions / Q000494:pharmacology / Q000627:therapeutic use*; D010101:Oxygen Consumption / Q000187:drug effects*; D012151:Resuscitation / Q000379:methods*; D000077325:Ringer's Lactate; D012771:Shock, Hemorrhagic / Q000188:drug therapy* / Q000503:physiopathology; D012965:Sodium Chloride / Q000494:pharmacology / Q000627:therapeutic use*; D013552:Swine
chemical_list: D007552:Isotonic Solutions; D000077325:Ringer's Lactate; D012965:Sodium Chloride