Moglobin) and LX20 (sodium, potassium and chloride) analysers (Beckman-Coulter). Samples were compared via a paired t test. Results Two hundred and thirty-eight paired samples were collected over a 2-month period. The correlation coefficients between arterial blood gas analysis and formal laboratory analysis for haemoglobin, sodium, potassium and chloride were 0.934, 0.945, 0.817 and 0.922, respectively. There was no significant difference between the two methods of measurement in this study when measuring these variables (P < 0.001) Conclusion Arterial blood gas analysis is an accurate method of measuring haemoglobin, sodium, potassium and chloride in the critical care unit. The transfusion practice and electrolyte or fluid resuscitation can therefore be accurately guided by the arterial blood gas measurements. This will be dependent on the accurate and regular calibration of the measuring device.P238 PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/6800653 Contribution of perfusion-related, metabolic and respiratory components to gastric mucosal acidosis in acute cardiorespiratory failureS Jakob1, I Parviainen2, E Ruokonen2, J Takala1 1University Hospital -- Inselspital, Bern, Switzerland; 2University Hospital Kuopio, Finland Critical Care 2006, 10(Suppl 1):P238 (doi: 10.1186/cc4585) Introduction Local mucosal acidosis in acute circulatory and respiratory failure is influenced by three main components: local perfusion and metabolism (mucosal rterial pCO2 gradient), systemic metabolic acidosis (arterial bicarbonate), and respiration (arterial pCO2). The aim of this study was to determine the effect of primary resuscitation on these components of gastric mucosal pH in surviving and nonsurviving patients admitted to the ICU. Patients and methods One hundred and three patients with acute respiratory or circulatory failure (age 63 ?15 years [mean ?SD], APACHE II score 20 ?6, SOFA score 8 ?3) were studied during the first 24 hours after ICU admission. Gastric air tonometers were inserted and arterial blood gases for the calculation of pHi andSAvailable online http://ccforum.com/supplements/10/SP240 Potential pharmacobiological and hormonal effects on resuscitationJ Wigginton, P Pepe, A Idris University of Texas Southwestern Medical Center and Parkland Hospital, Dallas, TX, USA Critical Care 2006, 10(Suppl 1):P240 (doi: 10.1186/cc4587) Objectives Studies have now clearly shown sex-related differences in the clinical presentations of women (vs men) with out-of-hospital cardiac arrest (OOHCA) and, more importantly, differences in the ability to resuscitate them. Presumably, these observations indicate potential pharmacobiological and/or hormonal factors. However, almost all out-of-hospital cardiac arrests (OOHCAs) occur in postmenopausal women aged >60 years. The purpose of this investigation was therefore to delineate any further stratification in sex-related differences when examining the outcomes of younger women and men (18 years) OOHCAs in an urban-EMS system with centralized protocols and medical direction using Utstein-style data guidelines. In terms of ability to resuscitate, the endpoints evaluated were return of spontaneous circulation (ROSC) and short-term survival (SURV) for those 50 years. Results Of the nearly 10,000 consecutive OOHCAs studied, 3926 were women (with 839 <50 years) and 5519 were men (with 1653 <50 years).