title: Comparison of Noninvasive pH and Blood Lactate as Predictors of Mortality in a Swine Hemorrhagic Shock with Restricted Volume Resuscitation Model.
abstract: Recent clinical studies have demonstrated that high blood lactate in the prehospital setting and poor lactate clearance in the emergency department are predictive of in-hospital mortality. This analysis of data collected from a swine model of hemorrhage and restricted volume resuscitation investigated the hypotheses that noninvasive muscle pH (pHm) and H clearance would predict mortality, and the responses would be similar between pHm and lactate. Data from a set of 57 swine were analyzed over the first 2 h after controlled hemorrhage and uncontrolled splenic bleeding. Surviving animals were ones that lived for the full 5-h experimental period. Venous lactate was determined at baseline, shock, and at 30, 60, and 120 min after injury. Spectra were collected continuously from the posterior thigh using a prototype CareGuide 1100 Oximeter and pHm calculated from the spectra; H concentration was determined from pHm. Lactate clearance rate was calculated from the difference in lactate concentration at 120 min and shock, and H clearance was calculated in a similar manner. Comparison of the area under the receiver operator characteristic curves was used to assess prediction of survival at 5 h after injury. At 120 min after injury, lactate, lactate clearance, noninvasive pHm, and noninvasive H clearance were equivalent predictors of mortality each with a receiver operator characteristic area under the curve of 0.87. Thresholds for single lactate (<3.8 mmol/L) or pHm (>7.30) determinations were found to be consistent with a resuscitation goal targeted to reverse acidosis. Continuous, noninvasive pHm monitoring may provide a substitute for lactate measurement in trauma patients, particularly in the prehospital and emergency department settings.
authors.affiliation: *Reflectance Medical Inc, Westborough, Massachusetts; and †US Army Institute of Surgical Research, San Antonio, Texas.
authors.forename: Babs
authors.initials: B
authors.lastname: Soller
authors.forename: Fengmei
authors.initials: F
authors.lastname: Zou
authors.forename: M Dale
authors.initials: MD
authors.lastname: Prince
authors.forename: Michael A
authors.initials: MA
authors.lastname: Dubick
authors.forename: Jill L
authors.initials: JL
authors.lastname: Sondeen
mesh_terms: D000818:Animals; D019540:Area Under Curve; D004195:Disease Models, Animal; D006470:Hemorrhage; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000097:blood*; D009132:Muscles / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D012372:ROC Curve; D012151:Resuscitation / Q000379:methods*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D012771:Shock, Hemorrhagic / Q000401:mortality / Q000628:therapy*; D019265:Spectroscopy, Near-Infrared; D013154:Spleen / Q000473:pathology; D013552:Swine; D013997:Time Factors
chemical_list: D019344:Lactic Acid; D010100:Oxygen