Acid Base Balance

Question 1

CL 96-106 meq/L

Answer 1

If Low - s/s metabolic alkalosis,
Hypoventilation,
(Chloride has an inverse relationship with bicarbonate. When serum chloride levels falls, due to gastrointestinal or renal loss, bicarbonate reabsorption often increases proportionally, resulting in metabolic alkalosis. Science Direct)
If High - s/s metabolic acidosis, Hyperventilation (body attempts to compensate for high acid gains)

Question 2

Na+ 135-145 meq/L

Answer 2

If Low - weak muscles, confusion, N/V, hypotension, coma if <115
If High - thirst, flushed skin, Liguria, hypotension, seizures

Question 3

K+ 3.5 - 5 mEq/L

Hyperkalemia can be d/t acidosis, MH, burn

Answer 3

If Low - muscle weakness, flaccid paralysis, PVCs, U wave

If High - peaked T waves, wide QRS, arrest

Question 4

Patient with serum potassium level 6.1 mmol/L. Expected ECG waveform with:

ventricular fibrillation
low T waves with U waves
peaked T waves
atrial fibrillation

Answer 4

low T waves with U waves

Question 5

Mg+ 1.5 - 2.5 mEq/L
Affects acethylcoline release @ nmj, regulates K+, opposes Ca2+

Answer 5

If Low - torsadas de pointes, wide QRS
If High - CNS depression, sedation, decreased reflex, hypotension, bradycardia

Question 6

Ca2+ 4.5-5.3 mEq/L
Critical for impulse conduction, contraction, coagulation

Answer 6

If Low - tingling around mouth or hands, weakness, twitching, ekg changes (prolonged QT interval), post op laryngospasm
If High- lethargy, short QT interval

Question 7

Patient experiencing tingling in toes, fingers, and mouth s/p total parathyroidectomy. Perianesthesia RN anticipates:

PTH level 8 picograms/mL
PTH level 100picograms/mL
calcium level is 15mg/dL
calcium level is 20mg/dL

Answer 7

PTH level 8 picograms/mL

Question 8

Controller of ADH

Answer 8

Hypothalamus

Question 9

Precursor of Angiotensin 1

Answer 9

RENIN which is produced by kidney > converted to Angiotensin1 > converted to Angiotensin 2 > stimulates adrenal glands to secrete Aldosterone

Question 10

Aldosterone

Answer 10

Increase Na+ absorption by exchanging K+ for Na+ in distal tubule if kidneys

Question 11

ADH

Answer 11

Released by hypothalamus

Question 12

Respiratory Acidosis

Common post-op causes?

Answer 12

Airway obstruction, COPD, limited chest expansion, Hypoventilation, Unresponsiveness, Residual muscle relaxant​, sedation​

Question 13

Metabolic Acidosis

Common post-op causes?

Answer 13

H+ (acid) gain or bicarbonate loss​ d/t K+ release from cells, lack of O2 (anaerobic metabolism), lactate production, muscle destruction (ex. Rhabdomyolysis, compartment syndrome​, severe bicarbonate loss (ex. Prolonged diarrhea)​

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Question 14

Respiratory Alkalosis

Common post-op causes?

Answer 14

Increased alveolar ventilation, blowing off of CO2 and losing acid d/t brain respiratory control centers dysfunction (e.g. s/p brain surgery), mechanical ventilation settings @ too high resp rate, Vt, anxious state lead to hyperventilation​

Why do these cause an alkalotic state?​

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Question 15

Metabolic Alkalosis

Common post-op causes?

Answer 15

Loss of acid (H+) or excess bicarbonate d/t excessive vomiting, gastric suctioning, excessive admin of corticosteriods​, loop diuretics leads to concentrated ​

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Question 16

ABG Normal Values?

Answer 16

pH 7.35-7.45​

PaCO2 35-45 mmHg ​

PaO2 80-100 mmHg​

HCO3- 22-26 mmHg​

Question 17

ABG Interpretation Step #1

Answer 17

Check the pH. Acidic if <7.35). Alkalosis if >7.45. Normal if 7.35-7.45.
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If Normal, either balanced or compensated.

Question 18

What is Compensated ABG?

Answer 18

Normal pH but abnormal HCO3- or PaCO2
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Question 19

ABG Interpretation Step #2

Answer 19

Check PaCO2. This is the respiratory component.

If <35 mmHg, and pH above normal, then​Respiratory alkalosis​
If >45 mmHg, and pH below normal, then Respiratory acidosis​

​If normal, go on to step 3 – this is likely metabolic related imbalance​

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Question 20

ABG Interpretation Step #3

Answer 20

Check the HCO3-. This is the metabolic component. ​

If <22 mmHg and pH below normal, then Metabolic acidosis​
If >26 mmHg and pH above normal, then Metabolic alkalosis​

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Question 21

Is PaO2 within normal range?

Answer 21

Normal 80-100mmHg

Question 22

What is mixed acid-base imbalance?

Answer 22

No clear correlation between pH and PaCo2 or HCO3-

Question 23

What is Oxyhemoglobin Dissociation Curve?

Answer 23

Affinity of O2 to hemoglobin

Question 24

What does Left Shift - Oxyhemoglobin Dissociation Curve mean?

Answer 24

Left Shift = higher affinity of O2 to hemoglobin, thus less O2 available to tissues. D/t alkalosis, hypocapnia, hypothermia, decreased levels of 2,3 DPG

Question 25

What does Right Shift - Oxyhemoglobin Dissociation Curve mean?

Answer 25

Right Shift = lower affinity of O2 to hemoglobin, thus more O2 available to tissues. D/t acidosis, hypercapnia, hyperthermia, exercise, pregnancy, increased 2,3 DPG

Question 26

What is Chvostek Sign?

Answer 26

It is a S/S of HYPOcalcemia, manifested by
twitching of facial muscles if cheek tapped over facial nerve

Question 27

What is Trousseau Signs?

Answer 27

It is a S/S of HYPOcalcemia, manifested by spasm of hand when BP cuff inflated)

Question 28

What are other s/s of HYPOcalcemia?

Answer 28

Laryngeal spasm

tingling around the mouth, hand, fingers, toes
weakness
twitching
EKG changes - Prolonged QT interval (hallmark sign)