Lactate and Base Deficit in Trauma January 19, 2007 James Huffman Emergency Medicine, PGY-1

Outline 1. Case 2. Lactate Physiology Clinical utility in trauma patients 3. Base Deficit Physiology Clinical utility in trauma patients 4. Summary

Case: Claresholm, Alberta 28M: MVC >130km/h, restrained, no airbag, EtOH, >30cm passenger space intrusion, BP 88/50 on scene Heathy otherwise, no meds, NKDA  Vitals: T: 36.2 C HR:104 RR:24 BP: 102/68 O 2 :98% on 15L nrb

Case: A – Patent. Able to vocalize B – Bilateral breath sounds C – Vitals as above. All pulses palpable, CRT 2sec. D – Moving all four limbs. No signs of head injury. E – Seat belt sign present. Abdo moderately tender. Pelvis stable. No obvious fractures/open wounds F – 2 IV’s running wide, Foley in. Brand new U/S, but not avail (being used by other ED doc for a gyne scan)

Question: How can you tell who is “sick”? How do you know if we’re making them better?

Resuscitation end points: Shock: “An abnormality of the circulatory system that results in inadequate organ perfusion and tissue oxygenation” (ATLS) Inadequate perfusion  inadequate O 2 delivery  anaerobic metabolism  acidosis Therefore, resuscitation is complete when O 2 debt is repaid, acidosis is eliminated and aerobic metabolism restored. Porter et al. J of Trauma; 44 (1998).

Lactic Acid History: sour milk

Pathophysiology

Type A Type B Decreased O 2 delivery  Shock (hypovolemia) Severe Anemia Hypoxemia CO poisoning Increased O 2 demands Inadequate O 2 utilization  SIRS  DM  Malignancy  Metabolic  Infections  Drugs/toxins Other  D-Lactic Acidosis

Lactate Pitfalls Anion Gap  Low albumin lowers the AG Ethanol Other Drugs/Toxins  Metformin  Propofol  Beta-2 agonists  Salicylates  Etc. Inborn errors of metabolism, G6PD deficiency Sampling location

Clinically… Useful in guiding resuscitation Elevated levels are predictive of mortality Time to normalize levels also strongly predictive Time to clear lactate<24h25-48h>48hDid not clear Mortality10%20%23%67% Husain et al. American J of Surgery 185 (2003)

Predicting Mortality

Base Deficit The amount of strong base that would have to be added to 1L of blood to normalize the pH Calculated from pH, PaCO 2 and HCO 3 - Usually more positive than -2mEq/L NOT simply an indirect measure of lactate  Elevated in other acidemic states (DKA, ASA tox, CRD)

Base Deficit In hemorrhage, this value becomes more negative before we see changes to pH and BP In pure hemorrhagic and septic shock, BD directly correlates with lactate levels Severely abnormal BD (≤ 10) in trauma patients is assoc. with significantly higher mortality, rates of ARDS and MOF Davis et al. J of Trauma; 44 (1998)

Base Deficit Largest clinical series conducted by Rutherford in 1992  Retrospective review of 3,791 trauma patients BD of -15 in patients <55 years without HI had significantly increased mortality If age>55 or HI present, BD of -8 showed significantly increased mortality

Which is better?

Take Home Points Lactate:  Normalized serum lactate appears to be a suitable end point for resuscitation  High initial lactate and moreover, time to normalize this value are predictive of mortality risk

Take Home Points Base Deficit:  A large negative BD (<-2mEq/L) may represent early hemorrhage/hypovolemic shock  Very high initial BD (>10-15) in trauma patients represents a significant mortality risk Resuscitation:  Correction of serum lactate and BD are reasonable markers of resuscitation

References: Adams, B., Bonzani, T. and C. Hunter The anion gap does not accurately screen for lactic acidosis in emergency department patients. Emerg Med J. 23; Davis J., et al Base Deficit is Superior to pH in Evaluating Clearance of Lactic Acidosis after Traumatic shock. J of Trauma. 44; Fall, P. and H. Szerlip Lactic Acidosis: From sour milk to septic shock. J. of Intensive Care Medicine. 20(5); Husain, F., et al Serum lactate and base deficit as predictors of mortailty and morbidity. American J of Surgery. 185; Jones, A. and J. Kline Shock. In Rosen’s Emergency Medicine. Concepts and Clinical Practice (6 th Edition). Philadelphia, PA: Mosby Elsevier. Nguyen, B., et al Severe Sepsis and Septic Shock: Review of the literature and emergency department management guidelines. Ann of Emergency Medicine. 48(1); Porter, J., and R. Ivatury In Search of Optimal End Points of Resuscitation in Trauma Patients: A Review. J of Trauma. 44;