Acid-Base Imbalances

1. bicarbonae (HCO3-)

2. Hydrocide (OH-)

bases that neutralize acids in the blood [2]

7.35-7.45

normal blood pH

[H+] in the blood

pH represents the levels of what in the blood?

It can add or remove charge (free radicals can add on to anything with an abnormal charge)

How does pH affect the ionization of molecules?

1. Ability of molecules to cross cell membranes

2. shape of the molecule

Ionization effects what in the body? [2]

it denatures them, they do not function well

How can changing pH affect shape of proteins?

Ions channels can change, altering neuomuscular activity or heart rhythm. (example)

How does changing pH affect the stability of cell membrane function or function of cell membrane components?

1. denatures proteins, do not function well

2. Alters stability of cell membranes or function of cell membrane components

3. enzymes cannot attach to substrate

Changing pH can cause a change in cell shape. How can this affect the body: [3]

1. buffering system

2. respiratory system

3. renal system

Three key mechanisms in regulation of pH

Bicarbonate system

Key buffering system

1. bicarbonate buffer system

2. protein buffer system

3. phosphate and ammonia

three major buffering systems

H⁺  + HCO₃^-   «  H₂CO₃ « H₂O  +  CO₂

chemical reaction for bicarbonate buffering system:

reaction goes to the right, more water and CO2 produced

In bicarbonate buffering system, what happens if [H+] increases?

reaction goes to the left, more H+ and HCO3- are produced

In bicarbonate buffering system, what happens if [CO2] increases?

If the carbonic buffering system does not rectify the imbalance within minutes the respiratory system will become active

how long until the respiratory system activates when blood pH is too low/high?

then hyperventilation occurs to blow off excess CO2

IN respiratory system, what happens if CO2 levels increase?

Hypoventillation to retain CO2

IN respiratory system, what happens if CO2 levels decrease?

1. primary: HCO3- is reabsorbed

2. secondary: H+ is excreted after all possible HCO3- is reabsorbed and imbalance persists

How does renal system alter blood pH? [2]

1. buffering systems

2. respiratory system

Compensation mechanisms for regulation of pH: [2]

Renal system (slower, takes hours)

Correction mechanism for regulation of pH:

1. partial: pH remains abnormal

2. Full: pH is normal but all other values abnormal

Compensation can be: [2]

• pH

• HCO3-

• pCO2

• pO2

• O2 saturation

What are arterial blood gas values measuring? [5]

pCO₂ = 34 - 45 mmHg

normal pCO2 ABG values

pO₂ = 75 -100 mmHg

normal pO2 ABG values

HCO₃^- = 22 - 26 mEq/L

normal HCO3- ABG values

O₂ saturation: >90%

normal O2 saturation ABG values:

acidosis

Too much acid (H+) in the blood. (if pH< 7.35)

Alkalosis

Too much base relative to acid in the blood. (if pH> 7.45)

1. metabolic acidosis

2. metabolic alkalosis

metabolic acid-base disturbances [2]

1. respiratory acidosis

2. respiratory alkalosis

Respiratory acid-base disturbances [2]

disturbances arise from either a problem with H⁺ or HCO₃^- ions

Primary defects for metabolic disturbances

•disturbances arise from a problem with CO₂

Primary defects for respiratory disurbances

­[H⁺] relative to HCO₃^-

Primary problem for metabolic acidosis

metabolic acidosis

•Occurs when there is an ­increase of any metabolic acid or loss of HCO₃^-

–Hypoxia (anaerobic metabolism to generate ATP ® buildup of  lactic acid ® ­[H⁺])

–Shock (SNS response ® vasoconstriction ® hypoxia)

–Heart failure ® ¯ oxygenated blood pumping ® hypoxia

–Ketoacidosis (type 1 DM DKA or starvation) – ketones are acidic

–Aspirin poisoning/overdose (acetylsalicylic acid)

–Diarrhea (loss of HCO₃^-  from lower GI ) too much acid

–Kidney disease (loss of renal HCO₃^- )  too much acid

causes of metabolic acidosis: [7]

1. low pH

2. decreased HCO3-

3. decreased CO2

ABG findings for metabolic acidosis with partial compensation[3]

Hyperventillaion to blow off excess CO2 from the right shift

why doe metabolic acidosis cause decreased CO2?

1. normal pH

2. decreased HCO3-

3. decreased CO2

ABG findings for metabolic acidosis with full compensation [3]

•Kussmaul’s respirations

•CNS/brain abnormalities: confusion, disorientation, decreased LOC, coma, death

•Muscle and nerve abnormalities

•Heart abnormalities (arrhythmias)

•Hyperkalemia (initial buffering: H⁺  excreted by kidneys and K⁺ reabsorbed)

Metabolic acidosis signs and symptoms [5]

Kussmaul’s respirations

Laboured, rapid breathing associated with metabolic acidosis:

decreased hydrogen ion concentration relative to HCO3-

Primary problem for metabolic alkalosis:

1. excess vomiting/NG suctioning

2. excessive intake of alkaline drugs (ex: antacids)

Causes of metabolic alkalosis: [2]

1. high pH

2. increased HCO3-

ABG findings for metabolic alkalosis:

•Slow, shallow breathing

•CNS/brain abnormalities: hyperexcitability

•Muscle/nerve abnormalities

•Heart abnormalities (arrhythmias)

•Hypokalemia:  Kidneys reabsorb H⁺ and excrete K⁺

signs and symptoms of metabolic alkalosis: [3]

Increased CO2

primary problem for respiratory acidosis:

1. respiratory centre is depressed (hypoventillation)

2. obstructive lung disease/pulmonary fibrosis

3. increased airway resistance with asthma attach

4. Pneumonia or pulmonary edema

causes for respiratory alkalosis: [4]

1. decreased pH

2. increased CO2

3. Increased HCO3-

ABG findings for respiratory acidosis with partial compensation

respiratory centre CAN’t compensate (that is the problem). Kidneys will try o correct by excreting H+

compensation for respiratory acidosis

1. normal pH

2. increased CO2

3. Increased HCO3-

ABG findings for respiratory acidosis with full compensation [3]

•Hypoventilation

•CNS abnormalities: Confusion, restlessness, disorientation

•Muscle/nerve abnormalities: muscle twitching, tremors, coma

•Cardiac abnormalities: arrhythmias

•Hyperkalemia (initial buffering: H⁺  excreted by kidneys and K⁺ reabsorbed)

Respiratory acidosis signs and symptoms: [5]

decreased CO2 due to hyperventillation

primary defect in respiratory alkalosis

•Anxiety

•Nervousness

•Agitation

•Pain

•Fever

•Sepsis (severe infection)

Resiratory alkalosis can occur with what? [6]

The respiratory system is one of the body’s compensation mechanisms, and that is the system causing the problem. The kidneys will correct by excreting bicarbonate

Why can’t body compensate for respiratory acidosis/alkalosis?

1. increased pH

2. decreased CO2

3. decreased HCO3-

ABG findings for respiratory alkalosis with partial compensaion [3]

1. normal pH

2. decreased CO2

3. decreased HCO3-

ABG findings for respiratory alkalosis with full compensation

•Hyperventilation

•CNS abnormalities: confusion, disorientation

•Muscle/nerve abnormalities: tingling, tremors, convulsions, coma

•Cardiac abnormalities: dysrhythmias

•Hypokalemia:  Kidneys reabsorb H⁺ and excrete K⁺

Respiratory alkalosis signs and symptoms: [5]