Investigations In An Unconscious Patient

DESCRIBE INVESTIGATIONS YOU WILL REQUEST FOR IN AN UNCONSCIOUS PATIENT

INTRODUCTION What

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

IMPORTANCE OF HISTORY Give

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 UNCONSCIOUSNESS Functional:

lack of substrate depression of

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

INVESTIGATIONS Imaging:

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

X-RAY Skull

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 & MRI CT-

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 SUGAR Must

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

pH Normal

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 GASES Important

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

ELECTROLYTES Monitoring

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 SCREEN Lfts

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 PUNCTURE Ensure

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 Ix Hemoglobin

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

OTHER Ix Myxedema

coma: Thyroid function

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