bmj quickfire Flashcards
what structures are located outside the BBB
hypothalamus
3rd & 4th ventricles
CTZ
what are the risk factors for bacterial endocartditis
Risk factors for bacterial endocarditis include:
acquired valvular heart disease with stenosis or regurgitation
Hypertrophic cardiomyopathy
previous infective endocarditis
structural congenital heart disease, including surgically corrected or palliated structural conditions, but excluding isolated atrial septal defect, fully repaired ventricular septal defect or fully repaired patent ductus arteriosus, and closure devices that are judged to be endothelialised
valve replacement.
-second dose advised if longer than 4 hours
-if material implanted, abx are needed
-abx prophylaxis agains infective endocarditis is not needed in upper GI, uro/gynae, ENT, resp
Tell me about Vecuronium
vecuronium:
-monoquarternary aminosteroid NDNMB
(Roc is also a monoquarternary amine, whereas Atrac and Panc are bisquarternary)
-Vec- mainly excreted in bile, but a small amount is excreted in urine.
Does not release norepinephrine unlike Panc
what is reynolds number
2000 (>2000 =turbulent)
Re=PVD/viscosity
PVD=density x velocity x diameter
hagen-poiseulle
what is the equation
whaat happens if radius halves
what happens if length doubles
Q=pie r4 P/ 8nl
if radius halves, resistance increases by 16 fold
if lengthh doubles, resistance will be doubled.
Tell me about cannabinoids
- what the active ingredient
does nalaoxone antagonise the analgesic actions?
how do they affect inflammation
whats the effect on intraoccular pressure
-9-THC is the active constituent
-naloxone blocks the analgesic actions
- synthetic cannabinoids reduce arachidonic acid-induced inflammation by inhibiting eicosanoid production
-cannabinoids lower intraoccular pressure
where is the most abundent store of iron in the body?
Haemoglobin is the most abundant store of iron in the body
iron is an essential micronutrient, as it is required for adequate erythropoietic function, oxidative metabolism and cellular immune responses. Although the absorption of dietary iron (1-2 mg/d) is regulated tightly, it is just balanced with losses.
There are 35-45 mg/kg iron in the adult body (about 4-5 g)
Iron is present in the following forms:
Haemoglobin 65%
Ferritin and haemosiderin 30%
Myoglobin 3.5%
Haem enzymes 0.5%
Transferrin bound proteins 0.1%
what is carboxyhaemoglobin
carboxyhaemogblobin : COHb (carbon monoxide attached to Hb)
-binding site-> Haem (Fe2+) site
prevents o2 binding causing hypoxia
what is carbaminohaemoglobin (HbCO2)
carbaminohaemoglobin: CO2 attached to Hb
binding site =>Globin, reversible
what oxygen delivery should be aimed for to meet the increased oxygen demand in sepsis (achieve the increased metabolic demands of a septic patient)
Maintain DO2 > 600ml/min/m2
DO2= CO x CaO2
CaO2=(Hb x 1.34 x SpO2) + (PaO2 x 0.023)
1.which nerve supplies posterior 1/3 taste and sensation of the tongue
- anterior 2/3 taste, anterior 2//3 sensation
- muscles of tongue except palatoglossal
- glossopharyngeal (IX) nerve supplies taste to posterior 1/3 of tongue
- anterior 2/3 taste= chorda tympani branch of facial nerve. (VII) (faces of 7deadly sins)
anterior 2/3 sensation-> lingual nerve branch of trigeminal.(V) 5 stars if you try
- tongue muscles-> hypoglossal nerve (XII)
what dose ST depression particularly in II, III, AVF indicate during CPET
underlying cardiac ischaemia and increased likelihood of postop cardiac complications, as it indicated compromised myocardial O2 supply
what is bile made of
alkaline, hypotonic electrolyte solution composed of bile pigments and salts.
+small amount of unesterified cholesterol
500ml bile is secreted per day
95% of bile salts are absorbed from the terminal ileum
what FGF is needed for D and E systems during SPONTANEOUS ventilation
FGF in D and E should be 1.5 times the total ventilation to limit rebreathing to 10%
name common adjuncts used in anaesthesia
adjuncts lower dose of each agent whilst maintaining analgesic eggicacy/ reduce duration or degree of side effects:
The most widely used adjuncts in anaesthesia include:
* Alpha 2 adrenergic drugs (clonidine)
* Anticholinesterases (neostigmine)
* NMDA receptor antagonists (ketamine)
* N-specific calcium-channel antagonists (ziconotide)
* Opioids
* Adrenaline.
what drugs potentiate (prolong) ND NMBs?
lithium
volatiles
MgSo4
aminoglyclosides e,g gentamicin
effects on arterioles:
- epinephrine (adrenaline)
- Norad
- decreased PO2
- Serotonin
- epinephrine (adrenaline)- vasodilation of skeletal arterioles.
-low does-B2 predominates (vasodilation)
-high dose- A1 predominates (vasoconstriction) - Norad- mainly acts on A1 (vasoconstriction), minimal B2 effects
- decreased PO2- vasodilation(hence increase CBF/ICP if low).
HOWEVER IN LUNGS low PO2-> hypoxic pulmonary vasoconstriction to optimise VQ mismatch - Serotonin (5HT)- mostly causes vasoconstriction, except skeletal muscles where it causes vasodilatation.
define antisialogogue
a drug that reduces or inhibits saliva production
by blocked parasympathetic muscarinic receptors e.g glyco, atropine hyoscine.
These drugs have mainly muscarinic activity with very little nicotinic activity.
hyoscine and atropine are naturally occuring esters. glyco is a syntehtic quarternary amine.
hyoscine hydrobromide has the greatest antisialogogue properties. It may cause anticholinergic syndrome as it cross BBB (hallucinations, ataxia, excitement)
hyoscine BUTYLbromid does not cross BBB significantly
what factors increase the MAC
Factors that increase MAC include:
Infancy
Hyperthyroidism
Hyperthermia
Catecholamines, amphetamines and sympathomimetics usage
Chronic opioid/alcohol use, and
Hypernatraemia.
how does clonidine work?
Clonidine is centrally acting alpha-2 adrenoreceptor and imidazoline receptor agonist that suppresses sympathetic outflow from the brainstem to the peripheral blood vessels.
Clonidine is centrally acting alpha-2 adrenoreceptor and imidazoline (II) receptor agonist. The receptors are located principally in the locus coeruleus sited in the brainstem (dorsal pontine tegmentum) and is composed of noradrenergic neurones. These cells are involved in the control of long-term synaptic plasticity, pain modulation, motor control, energy homeostasis, and control of blood blow. It reduces sympathetic outflow and increases vagal activity.
Clonidine is used as a treatment for hypertension, migraine and post-menopausal flushing. It also has anxiolytic, sedative and analgesic activity which makes it useful as a pharmacological adjunct in anaesthesia and intensive care. It does not have direct opioid activity but is used to manage opioid, alcohol and sedative withdrawal syndromes.
