ABG Flashcards
Acids have _ H+ ions & can _ a H+
Acids have MORE H+ ions & can DONATE a H+
Bases (alkaline substances) have _ H+ ions, can _ a H+ ions, & _ a hydroxide ion OH-
Bases (alkaline substances) have LESS H+ ions, can ACCEPT a H+ ions, & GIVE a hydroxide ion OH-
Strong acids
dissociate completely in solution
weak acids
dissociate partially
Hydrogen in important in the body because…..
Helps maintain cell membranes
Helps with enzyme activity
Component of H2O and keeps the body hydrated
Helps in energy production
Hydrogen is a component of ….
Sugars
Proteins
Starch
Fats
what is a neutral pH?
7
normal pH range
7.35- 7.45
normal CO2 range
35-45
normal HCO3 range
24-29
what is the most acidic place in the body?
the stomach
HCl found outside the stomach causes what?
damage
what. prevents the movement of gastric acid into the esophagus?
LES
true or false: pH is the same throughout the entire body
false, there are different pH ranges throughout the body
what electrolytes can acid-base affect?
Na+, K+, Cl-
can pH affect hormones?
yes
how does pH affect oxygen transport & delivery?
more acidic= hgb will GIVE up oxygen more readily at the tissue.
More alkalotic= hgb will HOLD on to oxygen & not give it to tissue.
what pH levels are incompatible with life?
<6.8 or >7.8
what are the 2 types of acids in the body?
Volatile acids & Non-volatile acids
Volatile acids
converted to gas
Excreted/eliminated by the lungs
Ex: Carbonic acid (H2CO3)
Non-volatile acids
Eliminated by the kidney, Exception – Lactic acid which is Metabolized by the body – primarily the liver and kidney.
ex. Lactic acid, Phosphoric acid, Sulfuric acid, Acetoacetic acid, Beta-hydroxybutyric
Body produces more acids than bases d/t (1), (2), (3).
Ingest in food/drink
Metabolism of lipids and proteins
Cellular metabolism waste product –CO2a volatile acid
what are buffers?
Chemicals in the body that combine with acid or base to change the pH.
Accept or release a H+
Almost instantaneous.
Short-lived.
List the 3 main buffer systems
Bicarbonate – Carbonic Acid Buffer
Phosphate Buffer
Protein Buffers: Hemoglobin
Bicarbonate – Carbonic Acid
Main ECF buffer
CO2 (byproduct of cellular metabolism) + H2O (in serum) = carbonic acid.
Carbonic anhydrase breaks down carbonic acid
In the lungs: H2O + CO2
In the kidneys: H+ + HCO3-
Phosphate Buffer
Main intracellular buffer.
H+ + HPO4-2 = H2PO4-
Hydrogen + hydrogen phosphate = dihydrogen phosphate ion
Protein Buffers
Nearly all proteins can function as buffers.
Carboxyl group (COOH): weak acid that gives up H+; Ex. Amino acid, Acetic acid.
Amino group (NH2-): accept H+; Ex. Amino acids, Ammonia NH3.
Hemoglobin is considered in this group, ‘picks’ up CO2 at the cellular level.
Increase in [H+] (concentration)=
pH decreases – more acidic
H+ move into the cell
More positively charged ions in the cell
K+ moves out of the cell
Electrical neutrality is restored inside the cell
respiratory mechanisms
Body produces CO2
CO2 + H2O = carbonic acid (H2CO3).
Exhalation excretes carbonic acid.
Doesn’t affect fixed acids (non-volatile) like lactic acid.
Body pH can be adjusted by changing rate and depth of breathing.
Kidney excretion
eliminate large amounts of acid except carbonic acid.
excrete base.
Can conserve and produce bicarb ions.
Most effective regulator of pH.
If kidneys fail, pH balance fails.
Depends on normal functioning of renal system.
how fast do buffers function?
almost instantaneously
how fast do respiratory mechanisms take to work?
minutes to hours
how fast do renal mechanisms take to work?
hours to days
Primary EVENT
The PROBLEM that initiates the acid-base imbalance
Primary DISORDER
What RESULTS from the primary event
Compensation mechanisms
Physiologic processes that adjust the pH back to the normal range.
which imbalances Increase or decrease CO2 & have Changes in ventilation?
Respiratory acidosis
Respiratory alkalosis
which imbalances have Changes in [H+] or bicarbonate ions?
Metabolic acidosis
Metabolic alkalosis
Metabolic Alkalosis
toomuchBicarb “OR” notenoughCARBONIC ACID
Metabolic Alkalosis Causes
Takingexcessbakingsoda,alka-seltzer=toomuchbase RESULTS IN hypokalemiacausinghydrogentoshiftouttheintracellularspaceandpotassiumgoesintothecell
Prolongedvomiting
NG tube
Diuretics
Metabolic Alkalosis CM
CNS over-excitability
Confusion
Tremors
Muscle cramps
Paresthesias
Coma
N/V/D
Respdepression
Metabolic Alkalosis ABG
pH- increased
CO2 – normal
HCO3- increases
paresthesias
tingling of fingers and toes, perioral
Respiratory Alkalosis
H²CO³ (CARBONIC ACID) DEFICIT in ECF
Respiratory Alkalosis ABG
pH- increased
CO2 – low
HCO3- normal
Respiratory Alkalosis Causes
Hyperventilation-primary event- CO2 blown off.
Increased metabolic demands- Fever, sepsis.
Medications
Acute anxiety
Hypoxia
PE or lung disease
CNS lesions
Ventilator settings
Respiratory Alkalosis CM
CNSover-excitability
Tachypnea
Lightheadedness
Confusion,blurredvison
Paresthesia
Hyperactive reflexes
seizures
Coma
Respiratory Acidosis
H²CO³ excess in ECF (too much acid/H+)
Respiratory Acidosis ABG
pH- low
CO2 – high
HCO3- normal
HCO3- WNL with acute respiratory acidosis; no time for kidneys to compensate.
Respiratory Acidosis Causes
Hypoventilation“primary event”- CO2 retained (H+).
cardiopulmonary arrest
head injury
narcotics/sedatives anesthesia
pulmonary disorders (acute asthma,COPD exacerbation, pneumonia, resp failure)
pain
abdominal distension
airway obstruction
chest wall deformities
neuromuscular problems
Respiratory Acidosis CM
CNS depression causing hypoventilation, dyspnea, respiratory distress, shallow respirations, H/A, restlessness, confusion
tachycardia, arrhythmias, LOC, stupor, coma
Metabolic Acidosis
HCO³ (BICARBONATE) DEFICIT in ECF.
excess acids are added OR bicarb is lost.
Metabolic Acidosis ABG
pH- Low
CO2- Normal
HCO3- Low
Metabolic Acidosis Causes
Renal failure
Fistulas
Diabetes (Type 1 DM-DKA)
Lactic Acidosis
Prolonged diarrhea(relative increased acid d/t loss of HCO3)
Starvation(body using fat for energy resulting in ketosis)
Medication overdose: ASA
Shock and cardiac arrest
Metabolic Acidosis CM
CNS: Lethargy, drowsiness, Confusion, Tremors, muscle cramps, Paresthesias.
Hypotension
Hyperkalemia
Deep breathing: Kussmaul respirations (DKA)
Fruity Odor Breath (DKA)
Respiratory Acidosis/Alkalosis:COMPENSATION.
the KIDNEY compensates by either: conserving (reabsorbing) HCO3 ions (acidosis correction) or excreting HCO3 ions (alkalosis correction)
Metabolic Acidosis/Alkalosis:COMPENSATION
the LUNGS compensates by either: conserving CO2 ions (hypoventilation/alkalosis correction) or excreting CO2 ions (hyperventilation/acidosis correction)
