Week 4- Fluid and Blood Transfusion Flashcards
Importance of thorough preoperative evaluation of fluid balance status
Patient History Systemic B/P Heart Rate Urine Output Hematocrit BUN Electrolytes CVP
Importance of thorough preoperative evaluation of fluid balance status Grandma?(class discussion)
we know grandma and grandpa area already dry. now they are super dry.
Perioperative Assessment of Intravascular Fluid Status
causes of intravascular volume depletion
Causes of Intravascular Volume Depletion Prolonged GI losses Chronic Hypertension Chronic Diuretic Use Sepsis Trauma
chronic hypertension
blood pressure maintain within 20% of baseline
Physical signs and symptoms of Hypovolemia
Supine Hypotension
(implies blood volume deficit greater than 30%)
Orthostasis or Positive tilt test
( increases in HR greater than 20 beats/min and decreases in systolic BP greater than 20 mmHg when the patient assumes the standing position)
Oliguria
Is Hematocrit a useful tool in determining hypovolemia?
Hematocrit a useful tool ?? Yes they will be concentration to a crit of 40%
What are some of the initial (early) signs and symptoms of hypovolemic shock
Hypovolemia shock- tachycardia- decreased urine out
Hemoconcentration
(hct is a poor indicator of blood volume). High Hct means the patient is dry
Azotemia
(nitrogenous products in blood)
Low urine sodium concentration
(less than 20 meq for every 1000 ml of urine)
Metabolic acidosis
(reflects hypoperfusion). Due to Na++ reabsorption
Body Fluid Compartments
Total body water is divided into:
ICF
ECF (PV + ISF)
TBW content varies with:
Age
Gender
Body Habitus
Hypervolemia
increases the risk of pulmonary edema
Hypovolemia
increases the risk of organ hypoperfusion
Intra-Operative fluid loss
Most fluid looses occurring intraoperatively are replaced with isotonic type solutions: Lactated ringers (LR) Plasmalyte (Normosol) Normal saline (NS)-used to dilute blood as well
colloids
They are high molecular weight solutions which tend to stay intravascularly. The half – life is approximately 3 – 6 hours
Indications for Colloid Solutions
Fluid resuscitation (hemorrhage) prior to transfusion Ex. Trauma Fluid resuscitation (hypoalbuminemia or protein loss) Ex. Burns
Blood Derived Colloids, name them
5 % albumin
25 % albumin
5 % plasma protein fraction
Heated to 60º C for 10 hours to decrease the risk of hepatitis or viral diseases
Synthetic Colloids
Dextrose starches
Dextran 70 (macrodex) MW 70,000
Dextran 40 (rheomacrodex) MW 40,000
Dextran 40 improves microcirculation blood flow because it decreases blood viscosity. It also has anti-platelet effects. (Vascular surgery)
Referred to as LMD (Low molecular Dextran)
More on Dextran…
Doses greater than 20 ml/kg/day can:
Interfere with blood typing
Prolong bleeding time
Cause renal failure
Cause anaphylactoid/anaphylactic reactions
Dextran 1 (promit) may be given prior to dextran to prevent severe anaphylaxis
Hetastarch (hespan)
6 % solution MW 450,000. Plasma expander less expensive than albumin
Anaphylactoid reactions are rare
Coagulation and bleeding times are not affected when infusions are not greater than 1 literMax. dose 20 ml/kg/day
Hespan 6% in saline and Hextend 6% in balanced electrolytes (Ca)
Half-life for 90% of hydroxyethyl starch particles is 17 days.- reaction will be down the road if it happens.
Do not use hydroxyethyl starch (HES) products, including Hespan®, in critically ill adult patients, including patients with sepsis, due to increased risk of mortality and renal replacement therapy (RRT).
Advantages of crystalloids
Inexpensive
Greater urine output
Replaces interstitial fluid
Disadvantages of crystalloids:
Short lived hemodynamic improvement
Peripheral edema
Pulmonary edema
Advantages of colloids:
Smaller infused volume
Prolonged increase in plasma volume (half life is 3 – 6 hours)
Minimal peripheral edema
Lower ICP (controversial)
Disadvantages of colloids:
Expensive
Coagulopathy (dextran more than hetastarch)
Pulmonary edema (capillary leaky states)
Colloids and Crystalloids
There is no evidence to support the superiority of either colloids or crystalloid containing solutions
Urine Output/Goal During Surgery
Adequate is 0.5 - 1 ml/kg/hour
Intraoperative Fluid Replacement
In healthy adults undergoing elective surgery, the following must be taken into consideration: NPO loss Insensible loss (third space) EBL Replacement Maintenance
Intraoperative Fluid Replacement
The predicted daily maintenance fluid requirements for healthy adults may exceed 2500ml/day. Insensible loss (diaphoresis, respiration, etc.) may exceed 1000ml/day Urinary losses to maintain renal function average 1000ml/day, GI losses 200ml/day
Intraoperative Fluid Replacement
Surgical Patients require additional fluids and electrolytes to replace losses from the ECF to nonfunctional “third space”
We base our fluid replacement on the anticipated need categorized by the amount and duration of tissue trauma caused
Insensible losses
500-1000mL/day (respiratory/cutaneous)
Evaporation
(most common from larger wounds)
Fluid shifts/internal redistribution (third spacing)
Ex. Burns, trauma, extensive injuries
The following is an accepted example of “third space” replacement
Minor trauma 2 ml/kg/hr *Values vary
Moderate trauma 4 ml/kg/hr between sources
Extensive trauma 8 ml/kg/hr
Keep in mind that colloids may be required if EBL is extensive
Calculation of Third Space Losses
Mild
(lower abdominal) 0 – 2 ml/kg/hr (hysterectomy, herniorrhaphy)
Calculation of Third Space Losses
Moderate
(upper abdominal) 2 – 4ml/kg/hr (colectomy, gastrectomy)
Calculation of Third Space Losses
Extreme
(combined upper/lower) 4 – 8 ml/kg/hr (thoracotomy, AAA repair)
Mobilization of third space fluids occurs in about 72 hours post-op
Mobilization of third space fluids occurs in about 72 hours post-op
Maintenance fluid
calculation
Maintained with isotonic solution
4cc/kg for the 1st 10kg of body weight (Up to 10 kg)
2cc/kg for the next 10kg of body weight (11- 20 kg)
1cc/kg for the rest of the body weight (21 kg and above)
hourly maintenance
Another option for hourly maintenance (approximation) in the adult patient is to use 1.5 cc/Kg/hr
Mostly done in emergency cases when calculations are not feasible
NPO Deficit
Deficit is described as the maintenance rate x the hours of NPO
Fluid maintenance administration per hour
Give ½ in the first hour, ¼ in the second hour, and ¼ in the third hour.
Formula to Calculate Adjusted Body Weight
actual patient weight + ideal patient weight /2
Ideal Body Weight
First 5 feet = 100 pounds then
For females add 5 pounds for every inch above 5 feet
For males add 7 pounds for every inch above 5 feet
Ideal Body Weight Obesity
Obesity is 20 % above the ideal body weight
Morbid obesity is twice the IDEAL BODY WEIGHT
Ideal Body Weight
morbid obesity
Morbid obesity is twice the IDEAL BODY WEIGHT
obese patient calculate fluid and drugs
For obese patients calculate fluid and drugs required according to the adjusted body weight
