Flashcards in Monitoring Drug Therapy Deck (60)
Why do we monitor patients?
1. Aids diagnosis and can identify the severity of disease
2. Allows more effective treatment with increase response and dose adjustments identified
3. Allows you to see ADRS- Renal and hepatic function, TDM drugs
Give some examples of what blood testing can monitor?
1. Urea and Electrolytes
3. Renal Function
4. Liver function
5. Cardiac Enzymes
Give some examples of what clinical observations can monitor?
1. Blood Pressure- pulse
2. Oxygen Saturations
3. Respiratory Rate
4. Urine output, fluid balance, daily weights
5. Pain Score
6. Blood glucose
7. Daily weights
What do urea and electrolyte tests indicate?
1. Renal function
2. Hydration Status
3. Disease status
4. Possible ADRs
Describe sodium and its role in the body?
1. Major Extracellular Cation- regulated by aldosterone (RAAS system- Angiotensin, Renin, Aldosterone)
2. Abnormal levels usual reflect water loss/imbalance rather than sodium loss/gain
3. Directly affects blood pressure
- low levels of sodium can cause hypotension
- Conversely large intakes of salt from diet can cause hypertension
Describe how hypernatraemia is caused when Na+ is more than 146mmol/L?
1. Insufficient fluid intake- increase in sodium stimulates thirst
2. Excessive water loss- vomiting or diarrhoea
3. Sodium retention, too much sodium in diet
4. Excess adrenocorticoid hormones (Cushings syndrome)
5. Pharmacological- corticosteroids, NSAIDS and lithium toxicity
Describe the consequences of hypernatraemia when Na+ is more than 146mmol/L?
1. CNS changes from lethargy/stupor to deep coma
2. Dependent on level, more than 170mmol/l is life threatening
3. Symptoms include: fever tachycardia, hypertension, dizziness, increased thirst, oedema
Describe how hyponatraemia is caused when Na+ is less than 133mmol/L?
1. Sodium depletion from various disease states:
- Loss from burns
- Severe skin lesions
- Excess swelling
- Fistulae, drains
- Vomiting and diarrhoea
- Haemodilution- caused by cardiac, hepatic, renal failure
- Infection and Carcinoma
2. Water retention
- Mineralocorticoid deficiency- Addisons disease
- ACE Inhibitors
What are some of the symptoms caused by hyponatraemia (caused when Na+ is less than 133mmol/L)?
5. Circulatory failure
8. Postural Hypotension
How do you treat Hypovolaemic hypornatraemia?
1. Replacement with IV NaCl 0.9%
2. Fluid restriction, diuretics and sodium restriction
How do you treat Euvolaemic Hyponatraemia?
Treat the immediate cause such as hormone replacement. IF not feasible, water restriction isn't recommended.
How do you treat someone with symptomatic issues of Hypo/hyperatraemia?
Use hypertonic saline 3% infusion
Describe potassium and its role in the body?
1. Largely intracellular who's needs are met from dietary sources
2. Essential for maintaining muscle contractility e.g. cardiac muscle
3. Maintains fluid balance, nerve impulse function and muscle function
Describe how Hyperkalaemia is caused when K+ is more than 5.3mmol/L?
1. Renal failure
2. Redistribution of K+ between ICF and ECF
3. Metabolic acidosis
4. K+ retaining diuretics
5. K+ supplements
6. ACE inhibitors, Angiotensin II receptor bockers, NSAIDS
8. Beta blockers (non-selective)
10. Azole antifungals
What occurs when K+ levels reach over 6 mol/L?
3. Ventricular Fibrillation
What are the treatment options of Hyperkalaemia?
1. Stop offering the medication
2. Restrict potassium intake
3. IV calcium gluconate 10%
4. Infusion of insulin and glucose
5. Ion exchange resins- calcium resonium
Describe how Hypokalaemia is caused when K+ is more than 3.5mmol/L?
1. Inadequate intake
2. Loss from GI secretions e.g. D&V
3. Redistribution between ECF and ICF
4. Mineralocorticoid excess e.g. hyperaldosteronism
5. Anaemia- immature RBCs
6. Drugs: Diuretics, Salbutamol, Theophylline, corticosteroids
7. Low potassium levels increase the resting membrane potential which means a great stimulus is needed to produce an action potential
Describe the symptoms that you feel when K+ falls below 2.5mmol/L (hypokalaemia)?
1. Muscular weakness
3. Respiratory failure
5. Cardiac Arrhythmias
6. Sudden death
How do you treat Hypokalemia?
1. Pottasium effervescent tablets
2. Intravenous pottasium (usually mixed with glucose or sodium chloride) at 20-40mmol/l
Describe calcium and its role in the body? How are the levels of calcium affected too?
1. Parathyroid hormone, Vitamin D metabolites (calcifedol and calcitriol), calcitonin are hormones which control it
2. Structural element in bones and teeth
3. Mediates vasoconstriction/dilation, nerve impulse transmission, muscle contraction and secretion of hormones (insulin)
4. Co-factor for enzymes and protein
5. Levels are affected by high or low albumin concentration
6. 40 to 50% are bound to plasma proteins and only free calcium is active
7. Levels of calcium must be adjusted for high or low albumin
8. Interpreting calcium results- corrected calcium favoured
Describe what Hypercalcaemia is?
1. The decreased serum PTH and increased serum calcitonin
2. It stops the calcium from being absorbed by the GI tract, decreases bone reabsorption, and increases calcium excretion from the kidneys
Describe how hypercalcaemia is caused?
4. Pharmacological reasons- antacids, calcium salts, thiazides and androgens, levothyroxine, lithium, excess vitamin D
5. Bone disease
Describe hypercalcaemia symptoms?
1. GI disturbances: anorexia, nausea and vomiting, constipation
2. Mental symptoms: fatigue, depression, psychosis
3. Headaches and generalised muscle weakness
4. Polyuria and increased thirst
What are signs of long term hypercalcaemia and how do you treat it?
1. Developing gallstones, reduced renal function, coma and death
2. Treatment: Discontinue and review drugs that promote it (thiazides, vitamin D analogues, calcium supplements) and correct dehydration.
5. Cinacalcet (for renal dialysis patients with parathyroid dysfunction)
Describe what Hypocalcaemia is?
1. Increased Serum PTH and decreased serum calcitonin
2. Encourages increased GI absorption of calcium
- Increased bone reabsorption
- Decreased renal calcium excretion
Describe how hypocalcaemia is caused?
3. Renal failure
4. Pharmacological (loops and bisphosphonates)
5. Inadequate vitamin D production/action
Describe hypocalcaemia symptoms?
1. Tend to be asymptomatic if it's mild hypocalcaemia
2. Severe cases- paraesthesia of face, tetany (muscle spasms), convulsions and paralysis
Describe hypocalcaemia treatment?
Calcium Gluconate 10% (10-20ml) as a slow bolus (+ ECG)
Describe phosphate and its role in the body? What do low levels indicate?
1. Phosphate is acquired through diet
2. Low levels can be implicated in development of rickets where vitamin D levels are low
3. Regulate acid and base balance