11/7/2015 HYPOVOLEMIA AND HEMORRHAGE • HUMAN CIRCULATORY SYSTEM OPERATES UPDATE ON VOLUME WITH A SMALL VOLUME AND A VERY EFFICIENT VOLUME RESPONSIVE PUMP. RESUSCITATION • HOWEVER THIS PUMP FAILS QUICKLY WITH VOLUME LOSS AND IT CAN BE FATAL WITH JUST 35 TO 40% LOSS OF BLOOD VOLUME. HEMORRHAGE AND DISTRIBUTION OF BODY FLUIDS HYPOVOLEMIA • TOTAL BODY FLUID ACCOUNTS FOR 60% OF LEAN BODY WT IN MALES AND 50% IN FEMALES. • BLOOD REPRESENTS ONLY 11-12 % OF TOTAL BODY FLUID. CLINICAL MANIFESTATIONS OF HYPOVOLEMIA • SUPINE TACHYCARDIA PR >100 BPM • SUPINE HYPOTENSION <95 MMHG • POSTURAL PULSE INCREMENT: INCREASE IN PR >30 BPM • POSTURAL HYPOTENSION: DECREASE IN SBP >20 MMHG • POSTURAL CHANGES ARE UNCOMMON WHEN BLOOD LOSS IS <630 ML. 1 11/7/2015 INFLUENCE OF ACUTE HEMORRHAGE AND FLUID RESUSCITATION ON BLOOD VOLUME AND HCT • COMPARED TO OTHERS, POSTURAL PULSE INCREMENT IS A SENSITIVE AND SPECIFIC MARKER OF ACUTE BLOOD LOSS. • CHANGES IN HEMATOCRIT SHOWS POOR CORRELATION WITH BLOOD VOL DEFICITS AS WITH ACUTE BLOOD LOSS THERE IS A PROPORTIONAL LOSS OF PLASMA AND ERYTHROCYTES. MARKERS FOR VOLUME CHEMICAL MARKERS OF RESUSCITATION HYPOVOLEMIA • CVP AND PCWP USED BUT EXPERIMENTAL STUDIES HAVE SHOWN A POOR CORRELATION BETWEEN CARDIAC FILLING PRESSURES AND VENTRICULAR EDV OR CIRCULATING BLOOD VOLUME. Classification System for Acute Blood Loss • MORTALITY RATE IN CRITICALLY ILL PATIENTS Class I: Loss of <15% Blood volume IS NOT ONLY RELATED TO THE INITIAL Compensated by transcapillary refill volume LACTATE LEVEL BUT ALSO THE RATE OF Resuscitation not necessary DECLINE IN LACTATE LEVELS AFTER THE TREATMENT IS INITIATED ( LACTATE CLEARANCE ). Class II: Loss of 15-30% blood volume Compensated by systemic vasoconstriction 2 11/7/2015 Classification System for Acute Blood FLUID CHALLENGES Loss Cont. Class III: Loss of 30-45% blood volume • MOST COMMONLY USED IS 500 ML OF Not compensated any longer ISOTONIC SALINE INFUSED OVER 10-15 MINS. Hypotension,impaired organ function • AN INCREASE OF CARDIAC OUTPUT BY 12-15% AS MEASURED BY NON-INVASIVE MEANS IS CONSIDERED AS EVIDENCE OF FLUID Class IV: Loss of >45% blood volume RESPONSIVENESS. MSOF , Severe Lactic acidosis Volume in Resuscitation in Septic Volume Resuscitation in Septic Shock Shock Cont. 1) Infuse 500-1000 mL of crystalloid or 300-500 5) Achieve MAP ≥ 65 mm HG mL of Colloid over 30 minutes 6) Positive fluid balance is associated with 2) Repeat as needed until CVP reaches 8-12 mm increased mortality in septic shock HG 6) Norepinephrine is preferred because it is 3) If hypotension persists after the initial more likely to raise BP then Dopamine and volume resuscitation, start Dopamine or less likely to trigger arryhthmias Norepinephrine. 4) Reduce volume infusion CRYSTALLOID VS COLLOID CRYSTALLOID AND COLLOIDS • CRYSTALLOIDS DIFFUSE READILY THROUGH A SEMI-PERMEABLE MEMBRANE: NORMAL SALINE • COLLOIDS DON’T READILY CROSS THROUGH A SEMI-PERMEABLE MEMBRANE: ALBUMIN 3 11/7/2015 DIFFERENT TYPES OF VOLUME COMPARISION OF DIFFERENT FLUIDS REPLACEMENT NORMAL SALINE VS PLASMA NORMAL SALINE VS LR • WHEN COMPARED TO PLASMA NS HAS A • THIS IS RELATED TO INCREASED NA LEVEL HIGHER NA AND CL CONCENTRATION, HIGHER FRON NS WHICH INCREASES THE TONICITY OF OSMOLALITY AND A LOWER PH. INTERSTITIAL FLUID AND PROMOTES NA • LACTATED RINGER IS MORE SIMILAR TO RETENTION BY SUPPRESSING RAA AXIS. PLASMA THAN NS. • INFUSION OF NS PROMOTES MORE INTERSTITIAL EDEMA THAN LACATED RINGER OR PLASMA-LYTE. EFFECTS OF FLUID REPLACEMENT ON PLASMA VOLUME AND INTERSTITIAL Plasma vs Intestitial Fluid FLUID VOLUME 1) Extracellular fluid accounts for about 40% of total body fluid 2) It is composed of Extravascular (Interstitial) and Intravascular (plasma) fluid compartments 3) Plasma volume is about 25% of interstitial fluid volume 4) 1 L of NS infused-750 mL will distribute in interstitial fluid and 250 mL in plasma 4 11/7/2015 RINGER’S LACTATE AND RINGER’S EFFECT ON PH OF BLOOD ACETATE • ONLY DIFFERENCE IS THE BUFFER LACTATE VS ACETATE • RINGER’S ACETATE IS PREEFERRED IN PATIENTS WITH IMPAIRED LIVER FUNCTION AS LIVER IS INVOLVED IN METABOLIZING LACTATE WHILE ACETATE IS METABOLIZED IN MUSCLE. • MAIN ADVANTAGE IS LACK OF EFFECT IN PH. • MAIN DISADVANTAGE OF RINGER’S SOLUTIONS IS THE CA CONTENT WHEN USED AS A DILUENT FOR PRBC’S WHICH CAN PROMOTE CLOT FORMATION. NORMOSOL AND PLASMALYTE HYPERTONIC SALINE • BALANCED SALT SOLUTIONS • 3% AND 7.5% NaCL SOLUTIONS ARE USED. • THEY HAVE MG INSTEAD OF CA AND CONTAIN • THEY ARE VERY GOOD IN ANIMAL STUDIES BOTH ACETATE AND GLUCONATE AS BUFFERS. FOR VOLUME RESUSCITATION IN • THEY CAN BE USED AS DILUENTS FOR PRBC HEMORRHAGIC SHOCK. TRANSFUSIONS. • HOWEVER NOT FOUND TO BE BETTER THAN • CLINICAL STUDIES HOWEVER SHOWS NO ISOTONIC FLUIDS IN CLINICAL STUDIES. BENEFIT OVER ISOTONIC CRSTALLOIDS. DEXTROSE SOLUTIONS COLLOID FLUIDS • INFUSION OF DEXTROSE SOLUTIONS CAUSE LESS • COLLOID FLUIDS HAVE LARGE SOLUTE INTRAVASCULAR VOLUME EXPANSION AND MOLECULES THAT DON’T READILY CROSS A MORE CELLULAR SWELLING. SEMI-PERMEABLE MEMBRANE. • D5NS HAS AN OSMOLALITY OF 560 mOsm/L AS YOU ADD 50 GMS OF DEXTROSE. • THE MOLECULES IN A COLLOID SOLUTION • IN CRITICALLY ILL PTS IN WHOM GLUCOSE CREATE AN OSMOTIC FORCE CALLED COLLOID UTILIZATION IS IMPAIRED, LARGE VOLUME OSMOTIC PRESSURE OR ONCOTIC PRESSURE INFUSIONS OF D5NS CAN RESULT IN CELLULAR WHICH HOLDS WATER IN THE VASCULAR DEHYDRATION AND EXCESS LACTATE COMPARTMENT. PRODUCTION. 5 11/7/2015 COLLOID FLUIDS COLLOIDS • HIGHER THE THE COLLOID ONCOTIC • HYPERONCOTIC ALBUMIN SOLS HAVE BEEN PRESSURE, GREATER THE INCREMENT IN ASSOCIATED WITH INCREASED RISK OF RENAL PLASMA VOLUME RELATIVE TO THE INFUSATE INJURY. VOLUME. • DEXTRANS AND HETASTARCH HAS BEEN IMPLICATED IN RENAL INJURY. • FLUIDS WITH COLLOID ONCOTIC PRESSURE OF • DEXTRANS PRODUCE A DOSE RELATED 20 TO 30 MMHG ARE CONSIDERED ISO- BLEEDING TENDENCY BY IMPAIRING PLATELET ONCOTIC FLUIDS. AGGREGATION AND DECREASE LEVELS OF FACTOR VIII AND VW FACTOR. COLLOID-CRYSTALLOID CONUNDRUM COST COMPARISION EARLY STUDIES SHOWED THE BENEFIT OF CRYSTALLOIDS FOR RESUSCITATION OF BLOOD LOSS. MORE RECENTLY COLLOIDS WERE FOUND TO BE BETTER IN IMPROVING CO AND SYSTEMIC OXYGEN DELIVERY. PRINCIPAL ARGUMENT IN FAVOR OF CRYSTALLOIDS IS THE LACK OF SURVIVAL BENEFIT WITH COLLOID RESUSCITATION AND THE LOWER COST OF CRYSTALLOID SOLUTIONS. 6 .