Data Interpretation Flashcards
When can haematological blood tests be abnormal?
- aneamia
- cancer
- sickle cell
- Haemorrhange - GI/PE bleed
- trauma
What comes under haematological tests?
FBC
- HB
- Mean Cell Volume
- Platelets
- reduced in - clotting disorders, alcoholics
- Raised in - lymphoma
- WCC
- Raised in = infection, leukaemia
- low in = recurrent infection, acquired immune suppression (HIV)
D-Dimer (when thrombus breaks down produces d-dimer)
- raised in DVT, cancer
Group + save/crossmatch
Coagulation
- INR
- Prothrombin
- Activated partial thromboplastin time
- Fibrinogen
- Thrombin
What comes under biochemical tests?
U+Es (kidney function)
- Na
- hypernatremia e.g. dehydration
- hyponatremic e.g. Addisons
- K
- hyperkalemia e.g. arrhythmia
- hypokalaemia e.g. drugs
- Creatine
- Raised e.g. kidney failure
- Urea
- Raised e.g. not perfused kidneys or being reabsorbed
CRP
- Raised in inflammatory process
Troponin T
- Shows myocardial damage has occurred
LFTs
- Bilorubin
- Raised e.g. jaundice
- always look at pre, intra and post when looking at kidneys + liver
- Albumin
- Protein
- Reduced = oedema as protein is needed to draw fluid back into the capillary bed
Pancreatic enzymes
- Amylase
- Lipase
Plain radiograph uses
- bones white as they absorb radiation
- air is dark
- if bones overlapping get increased whiteness
CT uses
Benefits;
- Good to look at bones
- Good for picking up big structure abnormalities
- Good to see when someone’s bleeding out
- Good for looking for cancer
Disadvantages;
- Exposing pt to lot of radiation
- Not good for looking at small soft tissue changes e.g. brain, spinal cord and nerves because it can’t pick up small details
Ultrasound uses
- No radiation
- Quick & cheap
- Good at looking at soft tissue; kidneys, liver, baby’s
Disadvantage;
- Very operational sensitive
MRI uses
- Can see damage in small soft tissue, good for;
- MS
- Epilepsy
- No radiation
What is the tool to view chest x-ray
Adequate
- Is it adequate - can you see from bottom of diaphragm to top of clavicle
Bronchial breathing
- Can you see trachea & bronchi & lung fields
Bones
- looking at rib cage for any fractures, dark areas over bone =could be neumothorax
Cardiac
- what is size of heart - enlarged could be cardiomyopathy
- Can u see boarders of heart, loss of contours around heart = fluid
- Pulmonary oedema appears as cotton wool
Diaphragm
- Can you see the diaphragm
Everything else
- scapula, clavicles
What comes under ABGs?
- PH (7.35-7.45)
- PO2 (10-14 kPa)
- PCO2 (4.5-6kPa)
- Base excess (-2 - 2)
- Bicarbonate (22-26 mmol)
- Lactate (0.5-1 mmol)
- HB
- Electrolytes
- Glucose (4-7.5)
- CO/MetHb
Define sepsis
Sepsis = Dissregulation of the inflammatory process
- Organ dissregulation (inflammatory cascade, hypertension, oedema)
- Cellular dissregulation - abnormal ATP production = lactate production
What is PH?
- concentration of hydrogen ions in a solution
- When a solution becomes more acidic the concentration of hydrogen ions increases and the pH falls
- Hydrogen ions are excreted via the kidney and carbon dioxide is excreted via the lungs.
- If the buffers e.g. plasma proteins and excretion mechanisms are overwhelmed and acid is continually produced, the he pH falls. This creates a metabolic acidosis.
What is base excess?
- This is the amount of strong base which would need to be added or subtracted from a substance in order to return the pH to normal (7.40).
- A base excess more than +2 mEq/L indicates a metabolic alkalosis.
- A base excess less than -2 mEq/L indicates a metabolic acidosis.
What is bicarbonate?
- Bicarbonate is produced by the kidneys and acts as a buffer to maintain a normal pH. The normal range for bicarbonate is 22 – 26mmol/l.
- If there are additional acids in the blood the level of bicarbonate will fall as ions are used to buffer these acids. If there is a chronic acidosis additional bicarbonate is produced by the kidneys to keep the pH in range.
- raised bicarbonate may be seen in chronic type 2 respiratory failure where the pH remains normal despite a raised CO .
What is electrolytes?
venous or arterial blood gas - check potassium + sodium - e.g. for management of cardiac arrhythmias
What is lactate?
- Produced as a by-product of anaerobic respiration.
- good indicator of poor tissue perfusion.
Glucose
- Glucose may also be raised in patients with severe sepsis or other metabolic stress.
What is Carbon monoxide?
At levels of 10 -20% symptoms such as nausea, headache vomiting and dizziness will be predominant. At higher levels patients may experience arrhythmias, cardiac ischaemia, respiratory failure and seizures.
What is methaemoglobin (metHb)?
MetHb is an oxidized form of haemoglobin. Levels of >2% are abnormal.
Respiratory compensation
- If a metabolic acidosis develops the change is sensed by chemoreceptors centrally
in the medulla oblongata and peripherally in the carotid bodies. - The body responds by increasing depth and rate of respiration therefore increasing the excretion of CO2 to try to keep the pH constant.
Metabolic Compensation
- In response to a respiratory acidosis, for example in CO2 retention secondary to COPD, the kidneys will start to retain more HCO3 in order to correct the pH.
- low normal pH with a high CO2 and high bicarbonate.
Respiratory Failure
Type 1 Respiratory failure (T1RF)
- PaO2 less than 8 and a PaCO2 which is
low or normal.
- Caused by pathological processes which reduce the ability of the lungs to
exchange oxygen, without changing the ability to excrete CO2.
- E.g. PE, pneumonia, asthma and pulmonary oedema.
Type 2 respiratory failure (T2RF)
- PaO2 of less than 8 and a raised PaCO2.
- You can think of it as being caused by a problem with the lungs or by a problem
with the mechanics or control of respiration.
Is a venous blood gas comparable to an arterial blood gas?
The values on a VBG and ABG are comparable (arterial and venous values are NOT significantly different for practical purposes) except in the cases of O2 and CO2.
