Acid-Base Imbalances

Bootcamp NCLEX - Cheat Sheets (Acid-Base Imbalances)

Lung, Kidneys, and buffer systems

Work together to maintain acid-base balance and homeostasis.

pH

hydrogen ion (H⁺) concentration

acidic

low pH = more H⁺ =

alkaline

high pH = less H⁺ =

ACID

Carbon dioxide (CO2) acts as an

Respiratory

Co2 imbalance = ___ imbalance

Respiratory Acidosis

Co2 retention

Respiratory Alkalosis

Co2 loss

BASE

Bicarbonate (HCO3-) acts as a

Metabolic

HCO3- imbalance = ___ imbalance

Metabolic Acidosis

HCO3- loss =

Metabolic Alkalosis

HCO3- retention =

Bicarbonate Buffer System

regulates pH by binding or releasing (H+).

7.35-7.45

Normal pH

35-45 mmHg

Normal PCO2

21-28 mEq/L (mmol)

Normal HCO3-

80-100 mmHg

Normal PaO2

>95%

Normal SaO2

H+

lungs and kidneys regulate ___ levels

Metabolic

Lungs compensate for _____ imbalances

Respiratory

Kidneys compensate for _____ imbalances

Quickly; within minutes to hours

Lungs (Respiratory) - works ___ within ___ to ___

Slowly; within hours to days

Kidneys (renal) - works ___; within ___ to ___.

Cellular buffering

Cells attempt to buffer pH imbalances by exchanging H+ for K+

potassium imblanaces

Cellular buffering can lead to

Hyperkalemia:

To correct acidosis, excess H+ shifts INTO cells, forcing K+ OUT = Hyperkalemia

• more H+ in cells = Hyperkalemia

Acidosis can lead to

Hypokalemia:

To correct alkalosis, low levels of H+ in the blood cause H+ to shift OUT of cells, pulling K+ IN = Hypokalemia.

• aLKalosis causes low K+

Alkalosis can lead to

acidic; High Co2 = Low pH ; Low Co2 = High pH

• Respiratory = Opposite

CO2 is

basic; ↑HCO3- = ↑pH ; ↓HCO3- = ↓pH

• Metabolic = Equal

Bicarb is

Respiratory Opposite, Metabolic Equal

ROME

opposite

Respiratory cause: PaCO2 moves ____ to pH

same

Metabolic cause: HCO3- moves in the ____ direction as pH

Uncompensated

pH abnormal, and only PaCO2 or HCO3- is abnormal

Partially compensated

pH abnormal, and both PaCO2 and HCO3- are abnormal.

Fully compensated

pH normal, but both PaCO2 and HCO3- are abnormal

ABG Interpretation

Identifying and treating the underlying cause

Priority for correcting pH imbalances

↑

• cardiac monitoring

Acidosis = __ K+

↓

• cardiac monitoring

Alkalosis = __ K+

Allen test

performed before puncturing the radial artery to ensure adequate circulation to the hand

1. Occlude ulnar and radial arteries until fingers blanch, then release ulnar artery.

2. Color should return in <5 s. If color does not return, choose another site

How to perform allen test

Apply firm pressure to the punture site for 5 min (longer if on anticoagulants) - prevents hematoma

Allen test Post-draw care

hyperkalemia

___kalemia occurs in acidosis

hypokalamemia

____kalemia occurs in alkalosis

prevents hematoma formation

Arterial Blood Draw, why hold pressure for >5 minutes

Respiratory Acidosis

Slow breathing, so much CO2

Respiratory Alkalosis

Too fast, too little CO2

• Obstructed airway (COPD)

• hypoventilation / bradypnea

• respiratory depression from opioid overdose

Causes of Respiratory acidosis

• hyperventilation (anxiety, panic attack)

• tachypnea (from hypoxia, high ventilator set rate)

Causes of Respiratory alkalosis

• assess - respiratory insufficiency

• improve ventilation / oxygenation

Collaborate with respiratory therapy to ↑ventilator RR.

Interventions for respiratory acidosis

• cyanosis

• dyspnea

signs of respiratory insufficiency

• promote slow breathing (paper bag, breathing techniques)

• Respiratory therapist - ↓ Ventilator RR

Intervention for Respiratory Alkalosis

Metabolic acidosis

• ↓ pH & ↓ HCO3-

• As - idosis - pooping

Excess bicarbonate loss / acid production

• ↓pH & ↑ K+

Metabolic alkalosis

• ↑ pH & ↑ HCO3-

• Ulk - alosis - vomiting

Excess bicarbonate retention / acid loss

• Severe diarrhea (bicarbonate loss)

• Renal Failure (acid buildup from impaired H+ excretion)

• DKA (ketone acid buildup)

• Shocks, sepsis (lactic acid buildup)

Causes of metabolic acidosis

• NG suctioning / Vomiting (loss of gastric acid)

• Diuretics (excess bicarb reabsorption)

Causes of metabolic alkalosis

• Kussmaul Respirations (deep, rapid breathing to exhale CO2)

Compensatory mech. for metab acidosis

• Bradypnea lungs retain CO2 to compensate)

Compensatory mech. for metab alkalosis

• IV fluids, insulin

• IV bicarbonate (severe)

Interventions for metab acidosis

• Monitor for K+ imbalances

• Replace fluids and electrolytes

Interventions for metab alkalosis

hypoventilaiton; ventilation

• BiPAP, bronchodilators, increased ventilator rate

Respiratory acidosis is caused by ventilation and requires intervention to improve ____

hyperventilation; slow breathing

• paper bag rebreathing, lower ventilator rate

Respiratory alkalosis is caused by ___ventilation and requires intervention to ___

bicarbonate loss; acid buildup

Metabolic acidosis occurs due to bicarbonate ___ (diarrhea) or acid ___ (DKA) ,

bicarbonate retention; acid loss

• severe vomiting, NG suctioning

Metabolic alkalosis results from bicarbonate ____ or acid ____.

Respiratory Acidosis

• decreased pH (acidotic)

• increased PaCO2 (acidotic)

• normal HCO3-

A client’s ABG shows an elevated PaCO2 level and a low pH. How should the nurse interpret these results?

1. Metabolic acidosis

2. Metabolic alkalosis

3. Respiratory alkalosis

4. Respiratory acidosis

A client with diabetes mellitus and an infection is at risk for diabetic ketoacidosis, which causes fat breakdown for energy, producing ketones (acid) and metabolic acidosis.

Which client is at highest risk for metabolic acidosis?

1. A client with COPD on oxygen

2. A client with type 1 diabetes mellitus who has an upper respiratory infection

3. A client with severe food poisoning experiencing vomiting

4. A client with severe anxiety who experiences a panic attack

1. Administer IV insulin - metabolic acidosis caused by DKA

2. Administer IV bicarbonate - severe metabolic acidosis

3. Implement continuous cardiac monitoring - causes hyperkalemia, monitor for dysrhytmias

4. Encourage slow breathing into a paper bag - corrects respiratory alkalosis

Which intervention should the nurse perform for a client with respiratory acidosis?

1. Administer IV insulin

2. Administer IV bicarbonate

3. Implement continuous cardiac monitoring

4. Encourage slow breathing into a paper bag