Question

ACID-BASE IMBALANCES:

Multitude of patient’s conditions can predispose them to different acid-base imbalances. Several patients were admitted in the medical-surgical ward and are put under your care. Answer the following questions pertinent to the patients’ conditions.

PATIENT A–admitted in the medical ward 30 minutes ago with chief complaint of severe dizziness and vertigo accompanied by frequent vomiting. As the patient moves, vomiting follows which is now recorded to be 7-8 times from the time of admission. Diphenhydramine 1 ampule TIV and metoclopramide 1 ampule TIV as stat doses were given to the patient.

PATIENT B–a dialysis patient who have stopped attending his dialysis session was admitted in the ward due to changes in sensorium. Serum creatinine level is elevated as well as the Blood Urea Nitrogen (BUN). Shallow respiration is noted upon the assessment of the patient.

PATIENT C–a patient was rushed to the emergency department and later was admitted to the ward with chief complaint of shortness of breath, numbness and tingling around mouth and fingers, and lightheadedness after taking a major examination in school. The patient was offered a brown bag by the admitting nurse.

PATIENT D–A patient with emphysema as admitted in the ward due to difficulty of breathing. The patient appears reddish and is complaining of lightheadedness. The patient was immediately hooked to oxygen therapy at 2 Lpm. Choose from the following ABG results which will be consistent with the patient’s condition:

A.pH 7.50 PaC02 31 HCO3 17

B.pH 7.30 PaC02 30 HCO3 18

C.pH 7.48 PaC02 49HCO3 30

D.pH 7.32 PaC02 50 HCO3 28

Patient A: __

Patient B: __

Patient C: __

Patient D: __

Explain why Patient B presented with shallow respiration in relation to the patient’s condition.

Explain why Patient D experiences lightheadedness and why the patientappears reddish in relation to the patient’s condition.

Explain the purpose of offering brown bag to Patient C as an emergency management for the patient’s condition.

Create a drug study for the medication: METOCLOPROMIDE specifying the following:

Drug classification

Mechanism of action

Indication (*for the case of the patient mentioned above)

Contraindication

Side effects

Nursing Considerations

Answer 1

Before we see the correct answers, let us acquiant ourselves with the basics of acid-base disorder interpretation:

Normal values:

Parameter	Normal value
pH	7.35 - 7.45
pCO2 (Partial pressure of carbon-dioxide)	40 - 45 mmHg
pO2 (Partial pressure of oxygen)	80 - 100 mmHg
Bicarbonate	22 - 26 meq/l

1. pH less than 7.35 = acidosis
2. pH more than 7.45 = alkalosis
3. pH and pCO2 value move in opposite directions
   1. If the pCO2 is high then the pH is low
   2. If the pCO2 is low then the pH is high
4. pH and Bicarbonate value in the same direction
   1. If the bicarbonate is high the pH is also high
   2. If the bicarbonate level is low the pH is also low
5. Acid base interpretation:

pH	pCO2	Bicarbonate	Interpretation
low (acidosis)	High	normal	Respiratory acidosis
High (alkalosis)	low	normal	Respiratory alkalosis
Low (acidosis)	normal	low	Metabolic acidosis
High (alkalosis)	normal	High	Metabolic alkalosi

• Whenever a acid -base disorder develops the body tried to compensate for it.
• The kidney and lungs are the main organs that participate in the compensation mechanism.

The compensation for acid-base disorder is as follows:

Primary disorder	Compensation
Respiratory acidosis	Metabolic alkalosis
Respiratory alkalosis	Metabolic acidosis
Metabolic acidosis	Respiratory alkalosis
Metabolic alkalosis	Respiratory acidosis

Patient A: Option C:

Explanation:

• Frequent vomiting causes loss of gastric acid in the vomitus
• This leads to metabolic alkalosis
• The pH in option: C is 7.48 ( which is more than 7.45). This pH is alkalotic
• Metabolic alkalosis is compensated by respiratory acidosis.
• This is achieved by reduce the respiratory rate.
• This leads to CO2 retention and thus increase in the pCO2.
• Another explanation for the high pCO2 is Diphenhydramine.
• This drug is first generation anti-histaminic drug. Sedation and CNS depression is a known side-effect of this drug.
• It reduces the respiratory drive and led to CO2 retention.

Patient B: Option B

Explanation:

• This patient is receiving dialysis. That means the patient is suffering from chronic kidney disease.
• Patients with chronic kidney disease have kidneys that are failing to function properly.
• This leads to retention of acids in the body. This leads to acidosis. (pH = 7.30)
• The bicarbonates try to buffer this but after a point are overwhelmed.
• Therefore, the bicarbonate level is low (18)
• Thus, this patient is suffering from metabolic acidosis.
• The lungs hyperventilate to compensate for metabolic acidosis.
• This reduces the pCO2 level.

Patient C: Option: A

Explanation:

• This patient is hyperventilating due to breathlessness
• As a result, there is CO2 wash out from the lungs.
• This leads to reduce pCO2.
• pH and pCO2 value move in opposite directions. Therefore, the pH increases (alkalosis)
• This patient is suffering from respiratory alkalosis.
• An alkalotic pH leads to hypocalcemia (reduce calcium levels in the blood.)
• Due to hypocalcemia, this patient has develop numbness in the perioral region.
• The kidneys tried to compensate for respiratory alkalosis by excreting bicarbonate.
• This leads to reduce levels of bicarbonate in the blood.  

Patient D: Option D

Explanation:

• This patient is suffering from emphysema.
• These patient have expiratory airflow limitation.
• This leads to incomplete exhalation.
• As a result, there is retention of carbon dioxide in the body.
• This leads to increase in pCO2.
• Increase in pCO2 leads to reduction in the pH.
• Therefore, this patient is suffering from respiratory acidosis.

Patient B is having shallow breathing because:

• This patient is suffering from metabolic acidosis.
• The body tries to compensate for metabolic acidosis by creating respiratory alkalosis.
• Increase in the H+ ions in the body stimulate the respiratory peripheral chemoreceptors and lead to increase in the rate of breathing.
• Therefore, this leads to rapid shallow breathing.
• This helps to achieve respiratory alkalosis.

Patient D is having lightheadedness and redness because:

• This patient is suffering from respiratory acidosis.
• In other words, this patient has low pH and high pCO2.
• High pCO2 causes vasodilatation - this gives rise to redness.
• Vasodilation causes hypotension - this give the sensation of lightheadedness.

Patient C is being provided with a brown bag because:

• This patient has hyperventilated.
• This causes CO2 washout.
• This reduces the pCO2 and increases the pH.
• This condition is called respiratory alkalosis.
• By asking the patient to breath in and out of the brown bag, we are making the patient rebreath his/her own exhaled air.
• Exhaled air is rich in carbon-dioxide.
• This promotes carbon dioxide inhalation and leads to increase in the pCO2 levels.
• This will help to normalize the pH.

Metoclopramide:

Classification:

• Functional classification - Prokinetic ( speeds up the gastric empty)
• Pharmacological classification - Dopamine antagonist

Mechanism of action:

• Increases the upper gastrointestinal motility
• Increases the tone of the lower esophageal sphincter.
• At higher doses, blocks the dopamine receptors in the chemoreceptor trigger zone in the CNS. Thus reduces the sensation of vomiting

Indication:

• Patient B is having recurrent vomiting.
• This has lead to loss of gastric acid and thus reduces the H+ ion in the body.
• This causes metabolic alkalosis.
• Metoclopramide is indicated in this case because:
  • It speeds up the gastric empty (movement of gastric content into the duodenum)
  • Increase the lower esophageal sphincter tone. Thus reducing reflux
  • Block the chemoreceptor trigger zone in the CNS.
• The overal effect is reduction in vomitting

Contra-Indications:

• Hypersensitivity to metoclopramide
• History of tardive dyskinesia or dystonia
• In presence of gastrointestinal hemorrhage, mechanical obstruction, or perforation.
• Presence of pheochromocytoma or other catecholamine-releasing paragangliomas.
• History of epilepsy

Side effects:

• Extrapyramidal symptoms like dystonic reaction
• Fatigue
• Restlessness
• Sedation
• Headaches
• Dizziness
• Galactorrhea
• Gynecomastia
• Impotence

Nursing consideration:

• Assess the patient for extrapyramidal symptoms
  • Acute dystonia - spasm of tongue, neck and face
  • Parkinsonism - tremor, shuffling gait, drooling, stooping posture
  • Akathesia - compulsive repetative motions and agitation
• Looks of gastrointestinal symptoms like nausea, vomiting and constipation
• If given orally, should be administered 30 mins prior to meals.
• The drug can cause oral dryness. This patient should be asked to rinse his/her mouth.