SAQs Flashcards
CNS Adverse effects of propofol?
Excitatory phenomena - hiccups, twitches, tremors, involuntary movements
Low therapeutic index between sedation and GA
Reduced cerebral blood flow
Symptoms of propofol infusion syndrome?
Metabolic acidosis (lactic)
Rhabdomyolysis
Hyperlipidaemia
Bradycardia arrest
Why does TEC 5 or other plenum vaporiser need an anti-spilling mechanism?
Previous spelling into bypass chamber
What is the safety system in place when two vaporisers are running at once?
Interlock system
What is the boiling point of des?
22.8 degrees, only slightly above room temp
What does Tec 6 do differently?
heating des to 39 degrees, 2atm
How does Tec 6 ensure that the flow of des is proportional to the carrier gas flow?
- Carrier gas flow restricted by an office, so that the pressure of carrier gas is proportional to gas flow
- Pressure transducer adjusts the resistor on des flow.
The resistor adjustment ensures that des flow is proportional to gas flow.
What is the component of aminophylline?
80% theophylline
20% ethylenediamine
What is the mechanisms of action of theophylline?
inhibits adenosine receptors to facilitate catecholamines from adrenal medulla.
High dose inhibit PDE
What are the side effects of theophylline?
Low therapeutic index. CVS - arrhythmia CNS - reduce seizure threshold Renal - weak diuretic Endo - increase secretion of gastrin and PTH
What is the 90% decrement time of servo at
- 30 mins
- 120 mins
- 300 mins
- 5- 10 mins
- 20 mins
- 60 mins
How much can naloxone reverse the effect of tramadol?
30% only
Describe the pathophysiology of aspirin toxicity
uncoupling of oxidative phosphorylation -> increase O2 consumption and CO2 production.
Children particularly at risk
What are the symptoms of aspirin toxicity
seizure, cerebral oedema, cardiac arrest
Overall effect of ageing on pain?
Reduced nociceptive response to noxious stimuli
Increased susceptibility to analgesic toxicity
Reduced ability to communicate
Frequently underrated
How does the CNS compensate for age related neuronal atrophy?
What’s the magnitude of this atrophy?
Redundancy - more neurons than required for normal function.
Neuroplasticity - more connections formed between remaining neurons
Neurogenesis - produce more neurons in hippocampus and basal ganglia
10% loss by age 80
Why is there a reduced SNS response to pain in the elderly?
Age related reduction in adrenergic receptors, compensated by increased level of catecholamine release -> overall reduce SNS tone.
Results in reduced SNS response to painful stimuli
Content of NaCl 0.9%?
154 mmol/L Na
154 mmol/L Cl
Content of 4% albumin?
40g/L albumin
Na 140 mmol/L
Cl 128 mmol/L
Octanoate 6.4 mmol/L
Specific indications for 4% albumin?
liver failure
Hypoalbuminaemia
Haemorrhage
Why is 4% albumin iso-oncotic?
Albumin content, large protein, bound to intravascular space.
provides 20-30 mmHg of oncotic pressure, hence iso-oncotic
IPPV effect on left heart?
Inspiration - initial increase in preload -> increase CO
followed by sustained reduction in preload
expiration - decrease PVR -> increase capacitance -> increase pulmonary blood volume -> further reduce LV preload
What is the FRC under anaesthesia / paralysis?
FRC 30 ml/kg on supine
25 with paralysis
Broadly speaking, what are the three main ways for kidneys to regulate body water?
- Regulate intake (low body volume -> renin -> ATII -> stimulation of thirst)
- Regulate GFR (auto regulation)
- Regulate reabsorption / excretion
