DESCRIBE INVESTIGATIONS YOU WILL REQUEST FOR IN AN UNCONSCIOUS PATIENT

INTRODUCTIONWhat

is unconsciousness? Requirements for one to be awake. Difference between coma and sleep. Abnormal drowsiness Stupor

IMPORTANCE OF HISTORYGive

an idea as to the investigations to be carried out Taken from a witness or by stander Ascertain if onset was sudden or gradual Abnormal behavior prior to onset Brief lucid interval?

CAUSES OF UNCONSCIOUSNESSFunctional:

lack of substrate depression of

function Abnormal function Structural: diffuse focal: supra or sub tentoriol

INVESTIGATIONSImaging:

X-RAY MRI CT-scan Blood glucose Electrolytes LFTs Blood gases & pH Drug screen Lumbar puncture

X-RAYSkull

fractures . Depressed? Calcified pineal gland: midline shift CXR: cardiomegaly, tb X-ray of bruised limbs & suspected fractures NB: In head trauma cases a c spine x-ray should always be sought.

CT & MRICT-

scan is useful in the case where SOL are suspected Imaging of the skull where images of higher definition than x-ray are required MRI may be used to view bleeds. Hypo dense?Hyperdense?

BLOOD SUGARMust

be done on every coma patient Normal fasting: 3.9-6.1mm0l/L Hypoglycemia is the most common cause of coma in diabetics Hyperglycemia causes hyperosmolar state osmotic diuresis with loss of sodium and potassium ions. May cause coma independent of

pHNormal

blood pH 7.35-7.45 Hypergycaemia,riased pH,kussmaul breathing, and ketotic breath point to diabetic ketoacidosis Lactic acidosis may complicate diabetic coma when tissue s become hypoxic. Lactic acidosis may itself cause coma. 1% of children with diabetic ketoacidosis develop brain edema& can cause coma. 25% mortality

BLOOD GASESImportant

if there is brain damage causing central pontine hyperventilation. Changes in respiratory pattern provide important and relatively objective evidence of deterioration. Normal blood gas levels:pO2 75100mmHg pCO2

ELECTROLYTESMonitoring

of potassium is important in management of diabetic patients. Total body potassium may be low but plasma levels normal: ECF volume is decreased due to polyuria potassium moves from cells to ECF when H+ conc. is high lack of insulin induced k+ entry into cells In severe acidosis NA+ is markedly depleted.

LFTs&DRUG SCREENLfts

deranged in hepatic coma, drug overdose Elevated aminotransferase levels Associated clinical findings e.g. jaundice *paracetamol OD may not cause coma but other drugs taken at that time may. *alcohol level may be misleading and other causes should be

LUMBAR PUNCTUREEnsure

intracranial pressure is not raised Levels of lymphocytes elevated in tb meningitis(100-300) normal(0-2) polymorphs 0-100, colorless In bacterial meningitis polymorphs are 200-2000, yellowish or turbid Neoplastic meningitis(infiltration)5-1000

BLOOD IxHemoglobin

can be used to asses bs control 4-6 wks prior to the test. Raised WBC,*mantoux test INR:hepatic coma,spotaneous bleed

OTHER IxMyxedema

coma: Thyroid function

tests. *loss of brain function as a result of long standing low levels of thyroid hormones.