8. Random Flashcards
What is tetany a/w
Produces by what
3
Does hyperparathyoid cuase it?
Tetany occurs in association with low plasma calcium or magnesium concentrations.
Thyroid surgery may produce iatrogenic hypoparathyroidism due to the removal of parathyroid tissue.
A respiratory alkalosis (not acidosis) would cause a low ionised calcium and may occur following hyperventilation.
Patients with untreated hyperparathyroidism become hypercalcaemic (not hypocalcaemic).
Osteomalacia is associated with tetany (not osteoporosis).
Vo2 - what is at rest
What conditions a/w high/est Vo2
Neonates
Term preg
Sepsis
Dobutamine
thyrotox
Resting oxygen consumption (VO2) is 3.5 ml/kg/minute (one metabolic equivalent or 1 MET).
Thyrotoxicosis 3.86 ml/kg/minute.
Oxygen consumption in young children is high: approximately 7 ml/kg/min at birth. The metabolic cost of respiration is higher than in adults and may reach 15% of total oxygen consumption. Similarly the metabolic rate in infants is almost twice that of adults and consequently alveolar minute volume is greater and the FRC relatively low.
At term of pregnancy, oxygen consumption at rest can increase by as much as 40% (5 ml/kg/minute) at term and further increase during labour to 60%.
In sepsis syndrome, VO2 and resting metabolic rate are enhanced by 30% (4.55 ml/kg/minute) compared with normal basal metabolism. VO2 falls in septicaemic shock.
Dobutamine hydrochloride was infused to 12 healthy male volunteers starting at a dose of 2 micrograms/min/kg and gradually increased to 4 and 6 micrograms/min/kg. Each dose of dobutamine was infused for 20 minutes. VO2 increased by 10-15%. (3.85-4 ml/kg/minute).
What is atmospheirc pressure
is fall in atmopsheric pressure linear
If air has water vapour - does this exert a PP
At what height will body fluids boil
Atmospheric pressure at sea level is 760 mmHg.
Because air is compressible the fall in atmospheric pressure with altitude is non-linear.
If 230 mmHg equals 100% atmospheric pressure then 21% is oxygen (this does not change with altitude), that is, 48.3 mmHg.
If the air has water vapour, it also exerts a partial pressure which will need to be subtracted from 230 mmHg.
Mitochondrial numbers increase as part of chronic acclimatisation, reflecting improved cellular oxygen use.
At 19200 m atmospheric pressure is only about 40 mmHg and body fluids will boil at 37°C!
ABG at altitude - how low kpa found
how much is atm pressure on mt everest - 8848 vs sea level
Arterial blood gas samples taken at 8400 m on Mount Everest (breathing air) by Grocott et al.1 found arterial partial pressures of oxygen of less than 4 kPa in all four of the subjects studied.
Atmospheric pressure on the summit of Mt. Everest (8848 m) is approximately one third that at sea level, about 34 kPa.2
what is the boiling point
The boiling point of a substance is the temperature at which the vapour pressure of the liquid equals the pressure above the liquid. Therefore, as atmospheric pressure falls with increasing altitude so does the boiling point.
What is SVP
is it affected by altitiude
Saturated vapour pressure is a function of temperature (not pressure). Therefore, at constant temperature, saturated vapour pressure is constant.
Is the FiO2 less at altitude
It is the inspired partial pressure of oxygen that falls with increasing altitude, the fraction of inspired oxygen remains constant. For example, on the summit of Mt. Everest, the fraction of inspired oxygen is still 0.21 but the partial pressure of oxygen is about 7.1 kPa (compared to about 21.2 kPa at sea level).
what is the best predictor of performance in endurance athletes.
The anaerobic threshold or velocity of lactate accumulation (VOBLA)
organ blood flow ml min 100g at rest
Organ Blood Flow(ml/minute/100g) Hepatoportal 58 Kidney 420 Brain 54 Skin 13 Skeletal muscle 2.7 Heart 87 Carotid body 2000 Thyroid gland 560
RR variability
does hr incease with inspiration or expiration
what causes it
what is it reduced by
The heart rate increases with inspiration and decreases with expiration, is not an abnormal rhythm and is most commonly seen in young healthy subjects. This “sinus arrhythmia” becomes less pronounced with age in patients with autonomic neuropathy (e.g. long-standing diabetes).
The changes in intrathoracic pressure with phases of respiration results in afferent baroreceptor stimulation relayed back as vagal efferent output leading to the slowing of sinoatrial node discharge.
Measuring this variability in heart rate is a reliable way to assess the parasympathetic innervation of the heart mediated by the vagus nerve.
R-R variability is diminished by increasing the depth of anaesthesia and has in the past been formed the basis of research in avoiding awareness during general anaesthesia.
This heart rate response is dependent on respiratory rate and tidal volume being maximal at approximately 6 deep breaths per minute. This response diminishes with a rise in respiratory rate and fall in tidal volume.
Heart rate variability with respiration is more marked in healthy young males compared with females
SA node automaticity
- rate of what
what is it influenced by
which produces what
The sinoatrial node has intrinsic automaticity (intrinsic pacemaker activity) at a rate of 100-110 beats per minute. The intrinsic rate is primary influenced by a balance between the parasympathetic (vagal) tone and sympathetic (T1-T4 ganglia). Vagal influence is dominant at rest, producing a normal resting heart rate of 60-80 beats per minute. A transplanted heart has no autonomic neural “hardwire” innervation therefore resorts to the intrinsic firing rate. The SA node will respond to endogenous and exogenous catecholamines.
Oculocardiac reflex
Stretch receptors extraocular muscles ->
Afferent short & long ciliary nerves->
Merge ophthalmic division trigeminal nerve @ ciliary ganglion->
Gasserian ganglion->
Nucleus trigeminal & vagus->
Efferent vagal fibres->
Inc para sympathetic tone & bradycardia
Nitric oxide -
Produce from
by
Results in what
inactivated by what
What is its second messenger
Nitric oxide is produced from L-arginine by nitric oxide synthase and is produced by the vascular endothelium in response to haemodynamic stress, and produces smooth muscle relaxation and reduced vascular resistance.
Nitric oxide is a free radical and may be inactivated through interaction with other oxygen free radicals, for example oxidised low-density lipoprotein (LDL).
It causes the production of cyclic guanosine monophosphate (cGMP) as a second messenger.
aLRODIIM HYPOTHERMIA
The UK Resuscitation Council’s guidelines on the management of cardiac arrest in hypothermic patients differ slightly from the standard algorithm.
In a patient with a core temperature below 30°C:
A total of 3 × DC shocks should be administered if on the shockable side of the algorithm (VF/VT)
Further shocks are not recommended until the patient is rewarmed to more that 30°C as the rhythm is refractory and so is unlikely to change
No drugs should be given as they will be ineffective.
In a patient with a core temperature between 30°C and 35°C:
DC shocks can be continued as normal
The time taken between drug doses should be doubled as they are metabolised much more slowly.
The patient should be actively rewarmed and protected against hyperthermia.
There is not enough information to know whether the resuscitation should be stopped so option e is false.
Starvation
48h
Bgl fall - decreased insulin - increased glucagon
mobilsation gylcogen - liver muscle
exhauisted in 24h
glcogenolysis then maintains
gluconeo-nutr 1-2 weeks
adapt ketones
FFA converted ketone body
Proteins stores - deplete 12days
Fat stores 25 days
