Anemia and Coagulopathy Flashcards
CaO2 formula
CaO2=(Hgb x 1.39)SaO2 + PaO2(0.003) 1.39 = O2 bound to hemoglobin SaO2= saturation of hemoglobin with O2 PaO2= arterial partial pressure of oxygen 0.003 = dissolved oxygen ml/mmHg/dl
Compensatory mechanisms for anemia
Increased cardiac output
Increased red blood cell 2,3-diphoshoglycerate (DPG)
Increased P-50
Increased plasma volume
Decreased blood viscosity
Decreased SVR
RIGHTWARD shift of Oxygen-Hemoglobin dissociation curve
Redistribution of blood flow to organs with higher extraction ratio (ER)
Changes that could interfere with oxygen delivery to tissues
Decreased cardiac output
LEFTWARD shift of Oxygen-Hemoglobin dissociation curve
Resp alkalosis (hyperventilation/ decreased PaCO2)
Hypothermia
Abnormal Hgb (including fetal Hgb and carboxyhemoglobin)
Anemia: basic anesthetic management
Know your patient’s preoperative
hemoglobin (Hgb)
hematocrit (Hct)
Anemia is suspected if hemoglobin
Chronic anemia anesthetic management
- Maximize O2 delivery
Consider ↑ FiO2 - Avoid drug-induced ↓ in C.O.
Selection of induction agent (etomidate)
Anesthetic technique (↑ opioid)
Hydrate, if tolerated; avoid hypovolemia - Avoid conditions that favor a leftward shift of the oxyhemoglobin dissociation curve
Avoid hyperventilation/ respiratory alkalosis
Avoid hypothermia - Volatile anesthetics
May be less soluble in plasma of anemic patient
May need less inhaled anesthetics for effect
Consider that this decrease in solubility may be offset by the impact of increased cardiac output
Goal of transfusion therapy
Goal of transfusion therapy
to increase oxygen-carrying capacity
correct a coagulation disorder
S/S of B12 deficiency anemia and anesthetic considerations:
B-12 deficiency may result in pernicious anemia
Bilateral peripheral neuropathy
Loss of proprioceptive and vibratory sensations in lower extremities
Decreased deep tendon reflexes
Unsteady gait
Memory impairment and mental depression
Anesthesia:
Avoid regional blocks due to neuropathies
Avoid nitrous oxide
Maintain oxygenation
Emergency correction for imminent surgery is with red cell blood transfusions
Folic acid deficiency anemia s/s and anesthetic considerations
Folic acid deficiency may result in pernicious anemia Smooth tongue Hyperpigmentation Mental depression Peripheral edema Liver dysfunction Severely ill patients
Oral manifestations may make airway management challenging (changes in tongue texture, etc.)
Have an alternate airway management plan!
What are some hemolytic anemias and their anesthetic considerations?
Hereditary spherocytosis:
Paroxysmal nocturnal hemoglobinuria
Glucose-6-Phosphate Dehydrogenase: Acute and chronic episodes of anemia
Need to avoid exposure to oxidative drugs
Avoid hypothermia, acidosis, hyperglycemia, infection
Perioperative risks and concerns of hemolytic anemia
Perioperative risks and concerns
↑ risk of tissue hypoxia
If previous splenectomy may have ↑ risk of perioperative infection
Increased risk venous thrombosis due to activation of coagulation
Erythopoietin is often prescribed for 3 days preoperatively
Acute drops in Hb below
Sickle cell disease avoid all situations leading to?
Hypoxemia
Hypovolemia
Stasis
Perioperative risks and concerns
Look for evidence of organ damage, cardiac dysfunction, concurrent infection
May benefit from conservative transfusions with high risk surgery
ASA recommends pre-operative transfusion to increase HCT to 30%
Goal of transfusion is to decrease Hgb S to less than 30%
Supplemental O2
Preoperative hydration for 12 hours prior to surgery
Pre-med
avoid respiratory depression leads to acidosis
Regional anesthesia is advocated
concern with hypotension
stasis of blood flow
compensatory vasoconstriction
Aggressive pain management
Avoid infections
Avoid tourniquets
What is acute chest syndrome and its treatment?
Acute chest syndrome-can be fatal (typically 2-3 days postop)
Pleuritic chest pain, dyspnea, fever, acute pulmonary hypertension
Transfusion or exchange transfusion to hct of 30%
Supplemental 02
Antibiotics
Inhaled bronchodilators
Aggressive pain management
Thalassemia perioperative risks and concerns
CHF common with severe anemia
Cardiac arrhythmias due to heart failure
Hemodynamic compromise with induction agents if low cardiac reserve-use cardiac sparing drugs
Very sensitive to the effects of digitalis
Hepatosplenomegaly
Coagulopathy (? Regional Anesthesia)
Hypersplenism can result in thrombocytopenia and ↑ risk of infection
Potential difficult airway 2° to maxillary deformities
Consider awake fiberoptic intubation
Complications of iron loading from chronic therapy
Diabetes (Blood glucose monitoring)
Adrenal insufficiency (↓ response to vasopressors)
Liver dysfunction & Coagulation abnormalities
Hypothyroidism & hypoparathyroidism
Arrhythmias (ECG)
Right-sided Heart failure (ECHO)
What is thalassemia major and minor?
Thalassemia major Inability to form beta-globin chains of hemoglobin Hepatosplenomegaly Dypnea and orthopnea Infection risk Arrhythmias , CHF Skeletal malformations Growth failure Hemothorax Spinal cord compression Mental retardation Very sensitive to digitalis Increased RBC production Jaundice
Minor:
Heterozygous state (trait)
Mild anemia
Normal RBC count
What is aplastic anemia?
Aplastic anemia refers to bone marrow failure characterized by destruction of rapidly growing cells
caused by drugs, radiation or infectious processes
Aplastic anemia risk and concerns
Patients on immunosuppressive therapy
Steroid “stress” dose should be considered
Reverse isolation due to thrombocytopenia and increased risk of infection
Prophylactic antibiotics due to neutropenia
Hemorrhage (GI & Intracranial)
LV dysfunction 2° high output state and fluid overload
Co-existing congenital abnormalities
Fanconi anemia is the peds version
Cleft palate; cardiac defects
Difficulty cross-matching blood products after multiple transfusions
Aplastic anemia induction, maintenance, and extubation concerns?
1. Preinduction/induction Consider transfusions before induction Airway hemorrhage possible with DVL Avoid nasal intubation Regional Anesthesia Labile hemodynamic response to induction 2. Maintenance PEEP will facilitate use of ↓ FiO2 Avoid nitrous oxide Maintain normothermia 3. Extubation and postoperative period Period with greatest O2 demands Monitor coagulation status
What is Methglobinemia?
Methemoglobin is formed when iron moiety in Hgb is oxidized from the ferrous (Fe2+) state to the ferric (Fe3+) state
Methemoglobin is a markedly left-shifted Hemoglobin that, due to its higher oxygen affinity, delivers little oxygen to the tissues
Normal level is 1%
At levels between 30% and 50%, -patients begin to exhibit symptoms of oxygen deprivation, blood is brown
from Nitrate poisoning, or local anesthetics: prilocaine
Anesthetic considerations
Can influence the accuracy of pulse oximetry as methhemoglobin absorps light equally in both red and infrared.
At Sa02 of >85% underestimates the true value
At Sa02 of
Clinical signs associated Acute Blood loss (20%EBV)
Tachycardia
Orthostatic hypotension
CVP change
Clinical signs associated Acute Blood loss (40%EBV)
Tachycardia Hypotension Tachypnea Oliguria Acidosis Restlessness Diaphoresis
Blood loss treatment?
Monitoring:
Invasive monitoring? (CVP, Arterial BP, +/- PA)
UOP - ? hematuria
Induction:
Ketamine/Etomidate
Maintenance:
May be unable to tolerate even modest levels of volatile anesthetics
Scopolamine, benzodiazepines, and opioids
Use vasopressors sparingly
Keep warm
Watch surgical field for non-clotting blood
Post-operative:
May require postoperative ventilation due to anticipated fluid shifts from resuscitation
Pulmonary edema
ARDS
Define massive transfusion and its considerations?
Defined as:
Transfusion of > 10 units of RBC in 24 hour period
Replacement of atleast one blood volume in 24 hour period
Replacement of 50% blood volume in 6 hour period
Associated with several consequences due to property of blood, agents to preserve blood and storage, tissue hypoperfusion
Hypothermia
Volume overload
Dilutional coagulapathy
Decreased in 2,3 diphosphoglycerate
Hyperkalemia
Citrate toxicity (binds calcium)
