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
Describe the symptoms of low level of phosphate?
1. Muscle weakness
3. Respiratory difficulties
Describe the causes Hypophosphataemia?
1. Inadequate intake
- malnourished patients
- interference with absorption (e.g. antacids binding phosphate- disease process- Crohn's disease)
2. Excessive loss
- phosphate my redistribute into cells
- Can cause hormonal effects, respiratory alkalosis, rapid cellular uptake
Describe how you can treat Hypophosphataemia?
1. Oral phosphate (4-6 tablets daily)
2. Intravenous Phosphate
3. Monitoring of other electrolytes is essential as calcium and potassium can be affected
- May need supplement calcium too especially if patient is hypocalcaemic
Describe the causes Hyperphosphataemia?
1. Renal impairment- accumulation of phosphate is common due inability to excrete it
2. Excess of vitamin D
Describe the treatment Hyperphosphataemia?
1. Phosphate intake ca be minimised by using "phosphate binders"
2. Taken at mealtimes to remove dietary phosphate
3. Calcium carbonate, aluminium hydroxide and sevelamer
Describe magnesium and its role in the body?
1. Essential for nerve and muscle function
2. Activates cellular enzymatic activity- metabolism
3. Accumulates in renal failure
4. Cause: Latrogenic and excessive antacids
Describe the causes Hypomagnesaemia?
1. Abnormal losses of magnesium from diet- secreted in GI fluid
2. Inadequate dietary intake
3. Chronic alcoholism
4. Accompanying hypokalaemia/hypocalcaemia
5. Pharmacological- Aminoglycoside antibiotics, Bisphosphonates, Immunosuppressants, prolonged diuretic therapy (loop and thiazide diuretics)
Describe the treatment of Hypomagnesaemia?
Mg salts if needed (oral and IV)
Describe how creatinine is produced and what the plasma concentration depends on?
1. Produced continuously as a by-product of normal muscle metabolism and is eliminated by the kidneys
2. Plasma concentration depends on muscle mass and breakdown, and the ability of the kidney.
- changes in creatinine levels can give an estimate of renal function
Describe the stages of renal disease and what occurs in each of them?
1. Pre-renal: reduced blood flow to kidneys- damage to aorta, dehydration causing hypovolaemia
2. Renal (intra-renal)- Kidney disease, renal artery
3. Post renal- kidney stone on urethra
how do you calculate creatinine clearance? What is the equation?
Urine creatinine concentration x Urine flow rate
Divided by serum creatinine concentration
How do you calculate the renal function?
1. By measuring the GFR (glomerular filtration rate)
2. Involves injecting a contrast dye into the kidney and monitoring the rate it travels in the kidney
3. You can estimate it using the MDRD equation
What is the purpose of measuring the eGFR and CrCl?
1. eGFR- capacity of the kidney
2. CrCl- kidney function
Why is it important to measure renal function, what does a rapid fall in creatinine clearance mean?
1. Rapid fall in creatinine clearance can be an indication of acute renal failure which can be prevented
2. Pharmacological treatment: nephrotoxic agents should be avoided, drug that are renally metabolised and excreted may require dose reductions
Describe the function of urea?
1. End product of protein metabolism
2. Increases due to renal failure, increased catabolism, GI bleeding, dehydration
3. Decreases with low protein diet and water retention
4. Useful indicator of hydration when compared with creatinine
- More than 15 suggests dehydration
- Less than 15 supports renal impairment
What is Haematology?
The examination of:
1. white bloods cells- increase if an infection is suspected
2. Red blood cells- essential for transporting oxygen to tissue, low levels indicate blood loss and anaemia
3. C-reactive protein- general marker for inflammation or infection
What are the two main types of white blood cells?
1. Neutrophils- increase in response to CRP seen in
- bacterial infection, auto-immune disease, acute phase response, inflammation
Describe red blood cells
1. Also named erythrocytes
- reduced count
- increased count- malignant disorders of bone, chronic inflammatory conditions, severe infectious illness, haemorrhage, surgery
4. Ferritin- iron status
What is prothrombin time?
1. A clotting factor that depends on vitamin K
2. Essential in activating clotting factors
3. Liver function impairment= absorption reduced= prothrombin production. PT will be increased.
What is the international normalised ratio? (INR)
Used to monitor the anticoagulant effect of warfarin
What is the activated partial thromboplastin time? (APPT)
Used for the monitoring of heparin
Describe the clotting cascade sequence?
1. Injured vessel- exposure to collagen to blood, damaged cell release phospholipids
2. Platelet plug formed- clotting cascade activated and prothrombin is converted to thrombin
3. Platelets and Fibrinogen to fibrin (clot)
How do you monitor liver function tests?
1. Liver function tests look at the expression of several enzymes in the liver which are raised due to damage
2. This includes ALT, AST, ALP, GGT
- Bilirubin- breakdown from Hb
- Albumin- protein made solely in liver
- Coagulation (INR and PT)
What are the type of damage that occurs to the liver overtime?
1. Acute hepatitis- Damage to liver leads to excretions of enzymes (ALT and AST) and clearance of bilirubin is reduced
2. Chronic liver damage- results in fibrous scar tissue building up in liver- this impairs the synthetic function so albumin and clotting factors get reduced
3. Chloestasis- blockage- substances are usually secreted by the liver accumulate due to impaired metabolism or excretion
What are the implications of hypertension and hypotension
Hypertension- increased risk of stroke, MY and renal impairment
Hypotension- dizziness, falls and collapse
What is postural hypotension?
1. Sudden drop in blood pressure when patient changes position from lying and sitting to standing
2. Can be caused by medications, diuretics, antipsychotics
- Leading cause of falls in the elderly
What is the normal pulse rate of a patient?
60 to 70 beats per minute
How does pyrexia usually start and at what temperature does hypothermia occur?
1. Usually caused by infection
2. Hypothermic usually begins at 35 degrees
Why is it important to measure urine output?
1. Indicates renal function and fluid status (dehydration, overload with fluids)
2. Higher may mean oedema and lower may mean renal failure and require diuretics to encourage kidneys to work harder
Why is it important to measure respiratory rate and how?
1. Number of breaths taken per minute (12-16)
- higher in patients with COPD and asthma
2. Drive by the level of carbon dioxide in blood
3. Patients may fail to expel the CO2 which affects the pH of the blood causing acidosis- leaves organs to fail
4. Opioid toxicity may cause low respiratory rate