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46 Cards in this Set
- Front
- Back
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Henderson-Hasselbach equation
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pH=6.1 + log HCO3-/H2CO3
pH=7.4, pK = 6.1, base = 24, acid=.03x40 =1.2 7.4 = 6.1 + 1.3 Hydrogen ion = 24 x pCO2/HCO3 |
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Acidosis
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a condition tending to lower pH, may or may not have acedemia, because partially corrected or mixed
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Buffers
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#1 hgb
#2 albumin Most important- bicarb - because easily changed with respiratory status |
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Acedemia
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arterial pH <7.4, all have acidosis
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Alkalemia
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arterial pH >7.4
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Alkalosis
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a condition tending to raise the pH
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BQ Fact
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Normal pH with acid problem = compensated disorder
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Anion Gap
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Cation - anions (Na-(Cl+HCO3))
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Decreased Anion Gap
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increase in unmeasured cations (hypergammaglobulinema) or decreased in unmeasured anions (hypoalbuminemia) - autoimmune, myeloma
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Total CO2
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1-2 mmol/L higher than true bicarbonate
bicarbonate + carbonic acid + carboamino proteins |
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Osmotic gap
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Difference between measured & calculated osmolality
2*na + Bun/3 + glucose/20 |
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Normal Osmolar Gap
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usu 10 - difference between measured & calculated osmoles
Increased osmolar gap = Increased uncharged substances (methanol, ethylene gylcol, ethanol, isopropanolol) |
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Methods of measuring osmolality
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Either freezing point depression or vapor pressure elevation (cannot use to measure ETOH, isopropanol, MEOH)
Except alcohols need to measure freezing point osmolality |
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Lactic Acid
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Collect in gray top to inhibit glycolysis
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Ketoacidosis
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Bhydroxybuterate (not measured in ketone assay) but contributes to anion gap. gets metabolized to acetoacetate. Ketones goes up (osmolar gap) & anion gap comes down in DKA.
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Acid base d/o - Rules Single Acid/Base disorders
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Bicarbonate & pCO2 always change in same direction
Metabolic disorders - in same dircetion as pH Respiratory disorders - in opposite disodrers Change in opposite directions - mixed disorder |
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Anion Gap Increases
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Only with metabolic acidosis
-pH, PCO2, HCO3 - in same direction Primary disorder - always has the |
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Compensation - respiratory disorders
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Alter renal excretion of HCO3
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Compensation - metabolic disorders
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Alter respiratory excretion of pCO2
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Metabolic Acidosis
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Increased Anion Gap - usu increased to acid - lactic acid, DKA (which replace bicarb)
Non Anion Gap - loss of bicarb w/ Cl increases to maintain balances - GI, Kidneys (RTA 1, 11, IV (Inc potassium ) -usually secondary diarrhea (villous adenomas, VIPoma) |
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DUMPSALE
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Increased anion gap - Diabeteic ketoacidosis, uremia, methanol, paraldehyde, salicylate, Alcoholic ketoacidosis, Lactic Acidosis, Ethylene glycol
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Metabolic Alkolosis
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Acid loss & dehydration - urine cl very low
Vomiting, dehydration (contraction alkalosis), mineralocorticoid excess (hyperaldosteronism, Cushing sydrome) assoc with inc Cl |
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Respiratory Acidosis
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Alveolar hypoventilation - obstructive lung disease (COPD), acute (depression respiratory center), impairs ventilation, neuromuscular problems,
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Respiratory Alkalosis
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Hyperventilation - anxiety - chronic hypoxemic (interstitial lung disease, shunting)
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Increased Anion Gap
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Replacement of HCO3 by the anion of some organic acid (lactate or acetoacetate)
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Compensation
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returns ratio of PCO2 to HCO3 toward normal
driven by pH, never overcorrects pH |
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Distinguish disorder is respiratory or metabolic primarily
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Degree of Change in pCO2 & HCO3
pCO2 will be more abnormal in respiratory HCO3- will be more abnormal in metabolic |
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Oxygen dissociation curve
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oxygen is released slowly to tissue as pO2 falls
Certain point were a slight drop in PO2 is accompanied by a significant drop in oxygen saturation |
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Right shift
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Right thing to do
Increase oxygen delivery to tissue increase pO2, temp, 2,3 dpg or H (decrease pH) |
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Left shift in oxygen dissociation curve
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More oxygen left on hemoglobin
decrease H(inc pH), low temp, 2,3 dpg, pCO2, carboxyhemoglobin, Hb F |
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Water composes this % of the human body
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60% of the human body
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Fluid compartments
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60% intracellular (protein, K, Mg)
40% extracellular(Na) (10%intravascular (protein), 30% interstitial) |
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Fluid loss
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1.5-2.0 L /day; 1L insensible
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Fluid Regulation
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Thirst
ADH Renin-Aldosterone -decreased renal blood flow or Na tubular delivery |
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Naturietic peptide system
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ANP/BNP/urodilatin - respond to cardiac stretch, inhibits renin;aldosterone & promote renal Na excretion.
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measured Na
Indirect ISE (ion sensitive electrodes) |
measured in dilute solutions - risk of pseudohyponatremia - because reduction in the proportion of plasma that is water (hyperlipidemia, hypergammaglobinemia)
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measured Na
direct ISE |
accurately measure sodium in undiluted solutions
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psuedohyponatremia
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sOsm >280 - hyperlipidemia, hyperproteinemia, hyperglycemia
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Urine Sodium
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maximally reabsorbed - FENa <0.5%
kidney wasted - FeNa >3% |
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urine osmolality
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excess water ingested - osmolality <50
ADH maximum concentration>900 |
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Hypernatremia
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loss of water & sodium w/o replacment
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Hyponatremia 5 causes
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pseudohyponatremia, osmotic fluid shifts, sodium wasting, excess water, edma
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Hyponatemia w/ nml serum osmos
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pseduohyponatremia & osmotic fluid shifts (occurs w/hyperglycemia, mannitol, glycine)
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Hyponatremia w/decreased serum osmos
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Sodium wasting (renal(diuretics, ATN) or extrarenal salt loss (GI, skin) - stimulates thirst & ADH production); Excess water (SIADH - CNS, pulmonary disorders, malignancy, meds); Edema (
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ratio of bicarb:pCO2
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20:1
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corrected anion gap
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Na-(Cl+HCO3) + 2.5(4-albumin)
use with hypoalbuminemia |
