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92 Cards in this Set
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Normal pH levels |
7.35-7.45 |
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Higher carbonic levels Lower metabolic levels = |
Respiratory acidosis |
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Lower respiratory levels Higher metabolic levels = |
Metabolic acidosis |
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ICF (intercellular fluid) |
2/3 - 3/4 of total body fluid |
How much of total body fluid? |
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ECF (extracellular fluid) compartments |
Interstitial and intravascular |
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Lymph system comprises which compartment of ECF? |
Interstitial fluid |
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Diseases related to fluid excess |
CHF and kidney failure |
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Issues related to fluid deficit |
dehydration and oral injury
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Principle ions for ECF and ICF |
ECF - Na and CL-
ICF - K+ and PO4 |
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Homeostasis |
total # of cations= total # of anions |
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Blood plasma osmolarity (0.9 NaCl) same as? |
Isotonic |
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Hypertonic solution
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greater osmolarity than plasma (50% glucose) |
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Hypotonic solution |
lesser osmolarity than plasma (0.45 NaCl) |
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Osmotic pressure Oncotic pressure Hydrostatic pressure |
- amount of fluid pressure to prevent osmotic flow of H20 between 2 solutions - pulling force exerted by colloids (eg. albumins in plasma) - pressure exerted by a fluid within a closed system. |
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Hydrostatic pressure forces fluid in or out of blood vessels? |
out |
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Oncotic pressure forces fluid in or out of blood vessels?
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in |
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**Net movement of water from plasma to tissue depends on which force is greater** |
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Triggers for thirst mechanism in hypothalamus are: |
hemorrhage intracellular dehydration excess angiotensin low cardiac output |
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Fluid output
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Losses counterbalance intake - 2500ml/day H2O in adult Main excretion organ is kidneys 1500ml/day |
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Other routes for fluid output are:
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insensible loss - skin as perspiration, lungs as water vapor noticeable loss - skin as sweat Loss through intestines as feces |
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Fluid output minimal obligatory loss
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500ml kidneys in 24hrs 30ml kidneys in one hour **less than either require immediate intervention |
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Control mechanisms for output ADH |
Stored in posterior pituitary Draws fluid into blood stream Less urine formed Osmoreceptors in the hypothalamus - stimulated by increased Na concentration of ECF Responds to increased osmolarity of blood Causes kidneys to retain urine |
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Control mechanisms for output Aldosterone |
- released from adrenal cortex in response to + plasma K levels - part of renin-angiotensin aldosterone mechanism to counteract hypovolemia - acts on kidneys to + reabsorption of Na and excretion of K and H - Na retention leads to water retention - overall effect is Na+ H2O retention - blood volume restored |
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Insensible fluid loss Skin - Exhaled air - sweat - feces/chyme - |
- by diffusion, controlled by outer layer of epidermis - 300-400ml/day for adults, +RR = +loss - provides body cooling by evaporation - passes to large intestines |
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Nutritional implications |
inadequate nutritional intake (body draws on protein) serum albumin decreases (adequate albumin needed for oncotic pressure gradient) edema(fluid not drawn into blood stream remains in interstitial space) |
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Extracellular fluid deficit (ECFD) Hypovolemia or dehydration caused by: |
abrupt decrease in fluid intake or marked increase in fluid output |
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Initial response to ECFD |
depletion of intravascular compartment -> fluid drawn from interstitial compartment -> fluid drawn from intracellular compartments **movement of fluid into body spaces (Interstitial>pleural>peritoneal) |
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Signs and symptoms of ECFD |
fast/weak pulse decreased BP + concentration of blood solutes (NaCl) oliguria or anuria **metabolic wastes accumulate and death ensues due to effects of acid waste products on cells |
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Extracellular Fluid Volume Excess (ECFE) can lead to: |
Hypervolemia + Blood volume circulatory overload edema |
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Interstitial spaces filled with fluid Extracellular osmotic pressure increases Fluid pulled from within the cells- results in edema Edema can develop with increased formation of interstitial fluid or impaired removal |
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Types of Edema |
Pitting edema – leave small depression Non-pitting edema – not a sign of ECF excess Anasarca – generalized body edema |
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Which type of edema has: -pulmonary edema -death by suffocation -commonly caused by left sided HF |
Anasarca
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-Excess fluid does not move into ICF -Normal serum Na and osmolarity -Drop in blood volume -ADH and aldosterone secretion – retain more fluid and Na |
ECFD |
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Electrolytes
(Na+) |
135-145 mEq/L
Regulated by ADH + Aldosterone Hyponatremia - due to net gain of water or loss of Na rich foods Hypernatremia = net loss of water or excessive Na |
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Electrolytes (K+) |
3.5-5.0 mEq/L Major cation in ICF Exchange with Na ions in kidney tubles Secretion of aldosterone Hypokalemia Hyperkalemia |
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Hypokalemia or K+ deficit |
alkalosis shallow respirations irritability confusion/drowsiness weakness/fatigue Arrhythmias, tachycardia lethargy thready pulse intestinal motility, nausea, vomiting |
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Hyperkalemia |
muscle twitches->cramps->paresthesia
irritability/anxiety drop in BP ekg changes dysrhythmias - irregular rhythm diarrhea |
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Electrolytes (Ca+) |
8.5-10.5 mg/dL 1% body's calcium in ECF Functions in bone formation, transmission of nerve impulses, muscle contraction Controlled indirectly by PTH secretion Hypocalcemia Hypercalcemia |
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Hypercalcemia |
May be hyperparathyroidism or neoplasm May be imobility |
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Hypocalcemia
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Chvostek's sign - contraction of facial muscles when facial nerve is tapped Trosseau's sign - carpal spasm induced by hypoxia. BP cuff around upper extremity |
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Magnesium (Mg++) – regulates or maintains neuromuscular activity in the body. |
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Phosphorus (PO4-) – with calcium is involved in bone and tooth formation. Also involved in many chemical activities |
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Acid-base imbalances |
Body's cellular activities require alkaline medium
Alkalinity + acidity are measured by pH scale pH - measure hydrogen ion concentration |
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Balance is maintained as long as the ratio of carbonic acid to bicarbonate ions is..? |
1:20 (eg. 1 H2CO3 (carbonic acid) 20 HCO3 (bicarbonate ions) **ratio is most important factor |
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Opposition of body’s alkalinity are chemical processes constantly producing acid Acids are by-products of metabolism pH is controlled by buffer systems in all body fluid and by respiratory and kidney regulatory systems |
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Buffer systems resists changes in pH by chemically binding excess H+ ions to prevent an increase in pH or by releasing H+ ions to prevent a decrease pH They do not neutralize – only decrease effects of strong acids or bases |
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3 Buffer systems in the body |
HCO3 (Bicarbonate) - controls pH of extracellular fluid in body HPO4 (Phosphate) - buffers fluids in kidney tubules + inside cells Protein buffer system - largest, 3/4 of all chemical buffering in body takes place inside cells + results from intracellular protein, HGB, nucleic acids |
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Respiratory regulation |
lungs regulate acid-base balance by elimination of CO2
CO2 becomes carbonic acid
More CO2, more carbonic acid is removed from blood, blood pH becomes more alkaline |
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Hyperventilation
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(rapid breathing) - example of a mechanism that raises pH |
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Hypoventilation |
(slowed/held breathing) - causes body to retain CO2 which is then available to for carbonic acid reducing the pH making blood more acidic
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Kidney(renal) regulation |
H ions + bicarbonate(HCO3) ions are formed in specific amounts as indicated by pH of blood pH decreases, H ions (acid) are excreted + HCO ions (base) are formed and retained\ pH increases, HCO3- are excreted + H ions are retained |
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Acidosis (Acidemia) |
blood pH lower than 7.35
occurs with increases in blood carbonic acid or decreases in blood bicarbonate |
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Alkalosis (Alkalemia) |
Blood pH over 7.45
Occurs with increase in blood bicarbonate or decrease in blood carbonic acid |
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A person will NOT become acidotic or alkalotic unless the normal ratio of 1:20 carbonic acid ions to bicarbonate ions is altered. |
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The primary cause of pH imbalance is indicated in terms of Metabolic or Respiratory. |
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Metabolic alkalosis or acidosis are imbalances brought about by changes in bicarbonate levels as a result of metabolic alterations |
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Respiratory alkalosis or acidosis are imbalances brought about by changes in carbonic acid levels as a result of respiratory alterations. |
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Compensation is a response of the body to correct acid-base imbalances. This is done by both the kidneys and lungs. In compensated acidosis or alkalosis, kidney and lungs are able to restore the altered ratio of 1:20, thus maintaining a normal pH. |
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When body reserves are used up it is uncompensated |
Ex- in compensated respiratory acidosis the plasma pH is maintained at normal even though there is an increase in the carbonic acid because the kidneys retain bicarbonate |
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Respiratory Acidosis
(Carbonic Acid Excess) |
Occurs when exhalation of CO2 is inhibited
Creates carbonic acid excess in body Caused by hypoventilation - CNS depression - Obstructive lung disease |
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Respiratory Alkalosis (Carbonic acid deficit) |
Occurs when exhalation of CO2 is excessive
Results in carbonic acid deficit Caused by hyperventilation - fever, anxiety or pulmonary infections |
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Metabolic Acidosis |
Occurs when levels of HCO3 (base) are lower in relation to carbonic acid molecules
Seen in starvation, renal impairment + diabetes. These conditions flood the plasma with acid metabolites |
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Signs + Symptoms of Metabolic Alkalosis |
Restlessness followed by lethargy Dysrhythmias (tachycardia) Compensatory Hypoventilation Confusion/dizziness/irritiable Nausea, vomiting, diarrhea tremors, muscle cramps, finger/toe tingle hypokalemia |
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Causes of Metabolic Alkalosis |
Severe vomiting
excessive GI suctioning Diuretics excessive NaHCO3 |
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Assessment Nursing history inquire about: |
Diet Fluid I/O S/S of electrolyte imbalance Disease processes (eg. kidney disease) Medications (eg. diuretics, steroids, K supplements) Treatments (eg. dialysis, TPN, tube drainage) |
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Clinical measurements (no MD order) |
Daily weights - each kg of weight gained or lost = 1L of fluid gained or lost
- balance scale - weighed same time each day - same scale or same/similar clothing |
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Vital signs may indicate fluid or electrolyte imbalance, acid-base imbalance or compensatory mechanism |
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Fluid I/Os - PO, IV, enteral feedings, irrigations, urinary/GI excretions
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I/Os SHOULD be the same 1500-2000ml/24hrs |
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Physical Examination Inspect: |
skin oral cavity eyes jugular veins veins of hands neurological system |
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Laboratory Tests |
Serum electrolyes level - routinely ordered Na, K, Cl, CO2 (bicarbonate) Anion gap - measures state of electrical neutrality between anion+cation groups in ECF **NORMALLY 11-17mg/L Helpful in diagnosing metabolic acidosis or alkalosis |
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Laboratory Tests CBC |
Hemoglobin/hematocrit levels - HCT measures the volume of whole blood that is composed of RBC's. Affected by change in volume **NORMAL HCT males 40-54% females 37-47% Decreased hemoglobin seen in severe hemorrhage |
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Osmolality - |
indicator of the concentration or number of particles dissolved in serum + urine
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Serum osmolality |
measure of solute (NA, glucose, urea) concentration of blood **NORMAL value is 275-300 mOsm/kg Increase in serum osmolality indicates fluid volume deficit, decrease fluid excess |
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Urine osmolality |
measures creatine, urea + uric acid in urine ** Males 390-1090 mOsm/kg Females 300-1090 mOsm/kg Increase in urine osmolality indicates fluid volume deficit, decrease indicates fluid volume excess |
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Urine pH (dipstick) normally urine is |
acidic pH 6.0 though range of 4.6-8.0 is considered normal |
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Urine specific gravity |
measure degree of concentration, normal 1.003-1.030 use a urinometer |
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ABGs |
Determine adequacy of alveolar gas exchange + evaluate ability of lungs + kidneys to maintain acid-base balance Measure pH, PCO2, HCO3-, PO2, and O2 saturation |
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ABGs Normal pH? |
7.35-7.45 |
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PCO2 |
measure of pressure exerted by CO2 dissolved in blood **NORMAL 35-45 mmHg |
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HCO3 (Bicarbonate) |
major renal component of acid-base regulation **NORMAL 22-26 mEq/L |
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PO2 |
measure of pressure exerted by oxygen in **NORMAL 80-100 mmHg in arterial blood |
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O2 saturation |
measures degree to which HGB is saturated with oxygen **NORMAL is 95-98 in arterial blood 60-85% in venous blood |
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ABGs Four requirements for analysis |
- Is imbalance acidic or alkalotic? - Is the primary disorder respiratory or metabolic? - Is there any compensation by the other system? - If compensation is present is it full or partial? |
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Interpretation of blood gases |
Below 7.35 - acidotic Above 7.45 - alkalotic Identify cause of pH by checking PCO2 + HCO3- alterations in PCO2 indicate respiratory, HCO3- indicates metabolic. |
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Determine whether the body is compensating for pH change. If both the PCO2 and HCO3- are abnormal, the direction of the deviation in concert with the PH will indicate which is the primary culprit and where the compensation is occurring. |
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POTASSIUM (K) GOES UP IN ACIDOSIS |
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Metabolic Acidosis Signs/Symptoms |
Headache Decreased BP Hyperkalemia Muscle twitching Warm flushed skin(vasodilation) Nausea/vomiting/diarrhea Changes in LOC Kussmaul respirations (compensatory hyperventilation) |
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Metabolic Acidosis causes |
DKA severe diarrhea renal failure shock |
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Respiratory Alkalosis Signs/Symptoms |
Seizures deep, rapid breathing hyperventilation tachycardia low or normal BP hypokalemia numbness/tingling of extremities Lethargy/confusion Light headedness Nausea, vomiting |
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Respiratory alkalosis Causes |
hyperventilation (fear, anxiety, PE) mechanical ventilation |
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Respiratory Acidosis Signs/Symptoms |
Hypoventilation ->hypoxia Rapid shallow respirations decreased BP with vasodilation dyspnea headache hyperkalemia dysrhythmias (Increased K) drowsiness/dizziness/disorientation muscle weakness/hyperreflexia |
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Respiratory Acidosis Causes |
Respiratory stimuli (Anesthesia, drug OD) COPD pneumonia atelectasis |
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