NS2P2. Mod 1. Lect 6. Acids & Bases

=>Plasma pH is an indicator of the concentration of H+ ions

-Increasesd H+ ions means ACID.

=>Normal arterial pH range is 7.35-7.45

• Higher pH (less H+) = alkalosis
• Lower pH (more H+) = acidosis

=>The metabolic processes constantly produce acids that must be either neutralized or excreted, there's three ways that this happens.

• ph is maintained by homeostatic mechanisms:
• Buffer systems: very fast
• Respiratory system: kicks in within mins to hours
• Renal system: kicks in within 2-3 days.

Acids: vinegar, stomach acid

Alkaline: baking soda, ammonia, draino

carbonic acid to 20 Base Bicarbonates. This is normal in body.

Maintain the normal 20:1 ratio of bicarbonate: carbonic acid and pH

-more effective with buffering an acid load than neutralizing excess of base.

• -react immedately
• Work to change strong acids into weaker acids or to bind acids to minimize/neutralize effects Carbonic acid

• - bicarbonate, monohydrogen
• -dihyodrogen phosphate, intracellular and plasma proteins, and Hgb buffers

Cannot work without adequate functioning renal and respiratory systems.

• Regulates bicarbonate level in ECF (HCO3)
• Normal range for bicarb is 22-26 mEq/L

In acidosis, kidneys conserve bicarb and excrete H+ to buffer blood.

In alkalosis, kidneys retain H+ (the acids) and excrete bicarb (get rid of base)

• Renal compensation is relatively slow
• -just balancing the system by letting go and keeping.

• -can be maintained indefinitely. Urine pH around 6.
• Can range from 4-8 in this compensation
• Begins to buffer in 24 hours, takes 2-3 days to reach this max.

If renal function is compromised , the body can no longer buffer ):

-brainstem control to CO2 LEVELS.

=>Controls PaCO2 and thus carbonic acid content of ECF

NORMAL range for PaCO2 is 35-45 mm Hg

In acidosis, ventilation increases to blow off CO2 (acid) to get rid of it.In alkalosis, ventilation decreases (HYPOventillation) to retain CO2

-reacts within minutes, and reaches max effectiveness within hours.

=> the lungs will help maintain normal CO2 in the water, the amount of CO2 is in blood is directly related to Carbonic acid concentration and subsequently H+ ion concentration.

Occurs when the ratio of 20:1(base: acid) is altered; Classified as respiratory or metabolic--symptom of underlying problem, must fix problem to balance.

Respiratory: imbalance of carbonic acid

Metabolic: imbalance of base bicarbonate

Imbalance may be acute or chronic

=> AlKalosis: Kicks the pH up (greater than 7.4) and AciDosis brings it Down (less than 7.4)

-Excess of Carbonic acid.

• =>Occurs w/ hypoventilation and CO2 retention
• Results in build-up of carbon dioxide
• Carbonic acid dissociates , liberating hydrogen ions (so ph goes down)pH decreases

• =>Causes
• COPD: cause
• Sedative/narcotic overdose: lowers RR
• Severe pneumonia, atelectasis: not exchanging oxygen for CO2
• Respiratory muscle weakness: weak resp

-If something wrong with resp, then kidneys will compensate by conserve bicarbs and secrete H+ ions into urine (occurs within 24 hours)

• Occurs w/ hyperventilation and CO2 deficit
• Primary cause is hypoxemia (decreased O2 in blood)

• =>Other causes
• Anxiety: deeep breathing out.
• CNS disorders
• Mechanical overventilation
• -Agressive hypoxemia needed to reverse this.

• =>Occurs w/ bicarbonate deficit
• Caused by build-up of acid other than carbonic acid (lactic acid, ketoacid)
• Caused when bicarbonate is lost from body systems (diarrhea)

• =>Either secondary to acid accumulation or actual bicarbonate loss
• DKA
• Shock
• Renal failure
• Severe diarrhea

-Resp will compensate: by CO2 isolation, get rid of extra acid by increasing RR.

-Kidneys try to excrete additional acid.

• =>Occurs w/ bicarbonate excess
• Occurs with loss of acid (prolonged vomiting, gastric suction)
• Occurs with gain in bicarbonate (ingesting baking soda)
• -more due to loss of acid in body
• -fasting deficit

• =>Either secondary to loss of acid or gain in bicarbonate
• Prolonged vomiting or suctioning
• Diuretic therapy
• Potassium deficit
• Excessive intake

Metabolic Acidosis: Low pH, Low BiCarb

Metabolic alkalosis: Low ph, High Bicarb

Resp Acid: Low ph, High CO2

Resp Alkalosis: High pH, Low CO2

Used to determine type of acid-base imbalance as well as oxygenation; blood taken out of arterial line, venous blood will alter results (not oxygenated

• -Alan's Test: block both sides of the circulation
• -assess circulation and cap refill after blood draw

• =>Normal results
• pH 7.35-7.45
• PaCO2 35-45 mmHgH
• CO3- 22-26 mEq/L
• PaO2 80-100 mmHg
• SaO2 >95%

1. Respiratory Acidosis pH <7.35, PaCO2 >45

2. Respiratory Alkalosis: pH >7.45, PaCO2 <35

3. Metabolic Acidosis: pH <7.35, bicarb <22

4. Metabolic Alkalosis: pH >7.45, bicarb >26

• =>Health history
• Diabetes, COPD, GI disorders, renal failure
• Medications (OTC, Rx, and recreational drugs)
• Surgeries
• Acute illnesses

=>Respiratory assessment

=>GI and GU assessment

No specific physical assessment to assess acid-base imbalance.

• =>Abnormal findings among major body systems:
• Neurologic
• Cardiovascular
• Gastrointestinal
• Neuromuscular
• Respiratory

Is it an acidosis or alkalosis?

Is it respiratory or metabolic?

Is compensation occurring?

1. Consider the pH: is it normal, high, or low?

2. Determine if the imbalance is RESPIRATORY or METABOLIC by evaluating the PaCO2 and HCO3

• -Example:
• pH >7.45 (alkalosis)
• If PaCO2 <35: respiratory alkalosis
• If HCO3- >26: metabolic alkalosis

is to determine if compensation is occurring

Lungs and kidneys compensate to return pH to normal

Compensation may be partial or complete

So if pH normal but other values abnormal: compensated acid-base imbalance

Drowsiness,confusion, dizziness, headache, coma

Cardio: low BP, Ventricular fib (related to hyperkalemia from compansation), warm flushed skin (due to peripheral vasoldilation)

GI: no changes

Neuro: seizures

Respiratory: Hypoventilation with hypoxia (lungs are unable to compensate when there is a respratory problem)

Drosiness, confusion, dizziness, headaceh, coma

Cardio: low BP, dysrhythmia (r/t hyperkalemia from compensation), warm flushed skin (r/t peripheral vasodilation)

GI: N/v, diarrhea, abdominal pain

Resp: Deep, rapid respirations (compensatory action by the lungs)

Neuro: dizzziness, light headedness, confusion, headace

Cardio: tachy, dysrhythmias (r/t hypokalemia from compensation),

GI: n/v, epigastric pain

Neuro: tetany, numbness, tingling of extermities, Hyperreflexia seizures

Resp: Hyperventilation (lungs are unable to compensate when there is a respiratory problem)

Neuro: dizzziness, light headedness, confusion, headace

Cardio: tachy, dysrhythmias (r/t hypokalemia from compensation),

GI: n/v, epigastric pain

Neuro: tetany, numbness, tingling of fingers and toes, muscle cramps, hypertonic muscles, seizures

Resp: Hypoventilation (compensatory action by the lungs)