Ch. 14 Flashcards
acid-base imbalances
- metabolic acidosis
- respiratory acidosis
- combined metabolic and respiratory acidosis
- metabolic alkalosis
- respiratory alkalosis
metabolic acidosis
- Overproduction of hydrogen ions
- Under-elimination of hydrogen ions
- Underproduction of bicarbonate ions
- Over-elimination of bicarbonate ions
*too much H+, not enough HCO3
causes of metabolic acidosis
- DKA
- Shock
- Severe Diarrhea
- Impaired kidney function
clinical manifestations of metabolic acidosis
- neuro
- respiratory
- GI (vomiting, diarrhea)
- cardiac (EKG changes)
respiratory acidosis results from
retention of CO
*too much CO2
causes of respiratory acidosis
respiratory disorder
- resp. depression
- inadequate chest expansion
- airway obstruction (COPD)
- reduced alveolar-capillary diffusion
CNS depression
- sedation
- head injury
acidosis: patient-centered collaborative care
- history
- CNS changes
- neuromuscular changes
- cardiovascular changes
- respiratory changes
- skin changes
- psychosocial assessment
neuromuscular changes with acidosis
- decreased muscle tone
- decreased DTR
cardiovascular changes with acidosis
early:
- increased heart rate
- cardiac output changes
worsening:
- hyperkalemia
- decreased heart rate
- T wave peaked
- QRS widened
- weak peripheral pulses
- hypotension
respiratory changes with acidosis
Kussmaul respiration (deep and rapid breathing)
skin changes with acidosis
(respiratory or metabolic acidosis)
- warm
- dry
- pink (vasodilation)
interventions for respiratory acidosis
- focus on improving ventilation and O2, maintaining patent airway
- drug therapy
- O2 therapy
- pulmonary hygiene
- ventilation support
- prevention of complications
drug therapy for respiratory acidosis
- bronchodilators
- anti-inflammatories
- mucolytics
interventions for metabolic acidosis
- hydration
- drugs
drug therapy for metabolic acidosis
- insulin to treat DKA
- antidiarrheal drugs
- bicarbonate only if serum bicarbonate levels are low
combined metabolic and respiratory acidosis is ___ than either form alone
- more severe than either form alone
uncorrected respiratory acidosis leads to
poor oxygenation and lactic acidosis
example of a problem leading to combined metabolic and respiratory acidosis
cardiac arrest
metabolic alkalosis
excessive base, and acid deficit
causes of excessive base
- excessive intake antacids (sodium bicarbonate or calcium bicarbonate)
- citrates (blood transfusions)
- IV sodium bicarbonate
causes of acid deficit
- prolonged vomiting
- excess cortisol
- hyperaldosteronism
- thiazide diuretics
- prolonged NG suction
hallmark of base excess alkalosis
ABG result with increased pH and increased bicarbonate level with normal O2 and CO2 levels
respiratory alkalosis is usually caused by
excessive loss of CO2 via hyperventilation
causes of hyperventilation
- anxiety (anxiety attack- hyperventilating)
- fear
- improper vent settings
- stimulation of central respiratory center due to fever
- salicylates
alkalosis: patient-centered collaborative care
- assessment (same for metabolic and respiratory alkalosis)
- hypocalcemia
- hypokalemia
- CNS changes
- neuromuscular changes
- cardiovascular changes (elevated)
- respiratory changes (elevated)
CNS changes with alkalosis
- positive Chvostek’s and Trousseau’s signs
neuromuscular changes with alkalosis
- tetany
interventions for alkalosis
- prevent further losses of hydrogen, potassium, calcium, and chloride ions
- restore fluid balance
- monitor changes
- modify or stop gastric suctioning, IV solutions with base, drugs that promote hydrogen ion excretion
the lungs have one chemical:
CO2
what organ is sick during respiratory acidosis/alkalosis
the lungs
sick lungs =
respiratory acidosis or alkalosis
- problem due to CO2
what are the compensating organs in respiratory acidosis/alkalosis?
the kidneys
- secrete bicarbonate and excrete hydrogen, bring pH back to normal
kidneys are _____ in compensating for respiratory acidosis/alkalosis
slow but effective
what organ is sick during metabolic acidosis/alkalosis?
the kidneys
- cannot maintain pH
what are the problem chemicals with metabolic acidosis/alkalosis?
- bicarbonate
- hydrogen
what are the compensating organs with metabolic acidosis/alkalosis?
the lungs
- blow off or retain CO2 quickly to correct metabolic acidosis or alkalosis
with metabolic acidosis/alkalosis, what chemical do the lungs work with to compensate?
- CO2
- the acid
arterial blood gas (ABG) normal values: pH
7.35-7.45
arterial blood gas (ABG) normal values: PCO2
35-45 mmHg
arterial blood gas (ABG) normal values: HCO3
23-30 mEq/L
arterial blood gas (ABG) normal values: PaO2
80-100 mmHg
laboratory assessment values: metabolic acidosis
pH: <7.35
bicarbonate: < 23 mEq/L
PaO2: normal
PaCO2: normal or slightly decreased
serum potassium: high
laboratory assessment values: respiratory acidosis
pH: <7.35
PaO2: low
PaCO2: high
serum bicarbonate: variable
serum potassium: elevated if acidosis is acute
laboratory assessment values: metabolic alkalosis
pH: >7.45
bicaronate: >30 mEq/L
PaO2: normal
PaCO2: normal or slightly increased (compensation)
serum potassium: may be low
laboratory assessment values: respiratory alkalosis
pH: >7.45
PaO2: normal
PaCO2: low
serum bicarbonate: normal
serum potassium: may be low
analysis of ABG
- look at pH draw arrow if it is high or low
- look at PCO2 (respiratory) draw arrow low or high
- look at HCO3 (metabolic) draw arrow low or high
low ABG =
acidosis
high ABG =
alkalosis
(ABG analysis) if PCO2 arrows are in opposite direction =
respiratory acidosis or alkalosis
(ABG analysis) if pH arrow and HCO3 arrow are in the same direction =
metabolic acidosis or alkalosis
(ABG analysis) compensation is present if the arrows ____
if arrows of PCO2 and HCO3 are opposite
(ABG analysis) partial compensation is present if the arrows ____
if arrows of PCO2 and HCO3 are in the same direction
decreased pH =
- acidodic
- increased hydrogen ions
increased pH =
- alkalotic
- decreased hydrogen ions
normal blood pH
7.35-7.45
acids
release hydrogen ions when dissolved in water or bodily fluids
bases
bind with hydrogen ions in solutions and lower the amount of free hydrogen ions in solution
buffers
can react either as acid or base
bicarbonate (HCO3-) ions are a relationship between
CO2 and hydrogen ions
acid base balance compensation: 3 ways
- buffers (bicarb, phosphate, protein, ammonium)
- respiratory system (adjusts CO2)
- renal system (controls bicarb)
which compensation method is the quickest response?
respiratory system
which compensation method is the longest response?
renal system (kidneys)
- takes 24-48 hours to respond
1st line of defense against changes in free hydrogen ion levels (pH)
buffers
common buffers
- bicarbonate (main buffer of ECF)
- phosphate
- blood proteins (albumin, globulins)
main buffer of ECF
bicarbonate
second line of defense against pH changes
respiratory system
- hypoventilation
- hyperventilation
physiologic conditions that lead the body’s response to hypoventilation
- decreased rate and depth of respiration (hypoventilation)
- inhibition of central chemoreceptors
- decreased PaCO2
- decreased H+
physiologic conditions that lead the body’s response to hyperventilation
- increased PaCO2
- increased H+
- stimulation of central chemoreceptors
- increased rate and depth of respiration (hyperventilation)
third line of defense against pH changes
renal system (kidneys)
strongest for regulating acid-base balance
the renal system (kidneys)
kidneys respond to pH changes by
movement of bicarbonate
compensation is when
body attempts to correct blood pH changes
fatal pH values
< 6.9 or > 7.8
homeostasis of acid-base regularity depends on
- hydrogen ion production being consistent and not excessive
- CO2 loss from the body through breathing, keeping pace with all forms of hydrogen ion production
