ANAESTHESIA A (38) Flashcards

Question

MATERNAL HAEMODYNAMIC CHANGES IN PREGNANCY

Answer 1

1. modest rises in HR & CO 2. modest _falls_ in BP 3. blood volume rises by 40%, but red cell mass by only 30%, producing a _relative anaemia_

Answer 2

* up to _500mls_ at NVD * up to _750 mls_ at caesarian healthy parturients can accomodate up to 1000mls loss without significant clinical symptoms

Answer 3

* Uterine massage is an important first aid measure in PPH, producing _uterine contraction_, ? via local PG release.

Answer 4

HELLP SYNDROME = the combination of * Haemolysis * Elevated LFT * Low platelets sometimes seen in pregnancy (cause?)

Answer 5

* pCO2 falls to ~_30mmHg_ in late pregnancy due to increased minute volume: * 'normal' pCO2 can indicate incipient respiratory failure!

Answer 6

REVIEW: * conventional reversal of NM Blockade uses ACETYLCHOLINESTERASE inhibitors like _NEOSTIGMINE_ to increase ACHO concentrations in the synaptic cleft, where it competes with the blocker molecules for access to the Nicotinic receptors of the NMJ. * this sort of _COMPETITIVE REVERSAL_ is only effective at modest depths of blockade * _SUGAMMADEX_ is a _direct acting_ reversal agent which binds and inactivates Aminosteroid relaxants (Roc\>Vec\>\>Panc, but not Atrac) and so can reverse even profound block. DOSE: * Normal reversal: 200mg (4mg/kg) * Emergency : 16mg/kg (both are effective in 1-2 mins)

Answer 7

* _SUCCINYL CHOLINE mimics ACHO_, binding to the NMJ and triggering contraction (then exhaustion). It occupies the receptor for 1-2 minutes before being metabolised by circulating _PSEUDOCHOLINESTERASE_, and muscle function returns. * _1 person in 33_ has _one_ defective copy of the pseudocholinesterase gene, prolonging the action of scoline to _5-10m_, although this is rarely evident clinically, & _1/1000_ have 2, prolonging duration to many hours. * _DIAGNOSIS_: * failure to regain muscle power after administration of Scoline (and despite Reversal - given for co-administered NONDEPOL relaxants) * no twitches * subsequent low activity on _Pseudocholinesterase assay_ * TREATMENT: supportive: ventilate until resolves

Answer 8

* Anterior Pituitary _TSH_ drives the thyroid to produce its 2 main\* hormones: * _T3 - TRI-IODOTHYRONINE_ * _T4 - THYROXINE_ * Production is predominantly the _long lasting T4_, and this is _converted peripherally_ to the _short_ _lived active form, T3_, which drives metabolic rate. * _THYROID FUNCTION_ is principally assessed by measuring TSH & T4 levels. * _normal TSH levels_ indicate N thyroid function (or adequate replacement) whereas raised levels indicate Thyroid failure (or occasionally Pituitary Tumour) * _normal T4 levels_ indicate adequate thyroid hormone production (or replacement) * _THYROID REPLACEMENT_ therapy is usually solely (synthetic) T4, with subsequent peripheral conversion to T3 in the usual manner. ## Footnote *\* the thyroid also produces the minor Calcium regulating hormone CALCITONIN, but this is secondary in importance to PARATHYROID hormone and Ca metabolism remains normal after thyroidectomy.*

Answer 9

Anterior Pituitary ACTH drives the Adrenal Cortex to produce 2 steroid hormones: * _CORTISOL_, which regulates BSL & metabolism * _ALDOSTERONE_, which regulates salt and water balance _ADDISONS DISEASE_ occurs when the Adrenal cortex stops producing these hormones, due to either: * Loss of _central drive_ * _Adreno-cortical failure_, eg due to _autoimmune attack_ or severe illness It results in * Hypoglycaemia * Hypovolaemia, hyponatrema and hyperkalemia → may present with circulatory collapse, an 'ADDISONIAN CRISIS' * Skin hyperpigmentation * Nausea and vomiting * Muscle pain and weakness Rx * Address hypoglycaemia and dehydration * Replace CORTISOL with HYDROCORTISONE\* * (consider) ALDOSTERONE replacment with FLUDROCORTISONE (often unneccesary) * Address the cause if able *\*Cortisol = Hydrocortisone,*

Answer 10

1. chose the correct tube, a LEFT\* 39 French for the typical M, and 37 for F 2. put stylet into ENDOBRONCHIAL Lumen and bend Left 3. rotate tip anteriorly, place thru cords & remove stylet 4. holding well proximally, corkscrew L 90 degrees whilst pushing firmly home to ~ 29cm at the teeth 5. inflate TRACHEAL cuff (5-10ml) & check bilat AE\*\* 6. inflate BRONCHIAL cuff (1-2ml) & check bilat AE\*\* 7. isolate and check each side - if wrong sided, insert fibrescope to tip of Bronchial lumen and pull back to carina under direct vision then direct into opposite side (if lost: recall that the cartilage arch is deficient posteriorly) ## Footnote * \* Left sided tubes are generally suitable for procedures on either lung, R sided tubes are only for surgery on the L main bronchus* * \*\* loss of one side, as per normal ETT, usually = too far in*

Answer 11

assuming the DLT is correctly sided and not too deep, (the usual cause) hypoxia likely represents _ongoing shunting_ through the collapsed upper lung: manage via * start with no lower lung PEEP (reduces blood diversion to upper) * add 5 cm lower lung PEEP * add 5 cm upper lung CPAP * discuss with the surgeon clamping the upper lung vessels or returning to 2 lung ventilation

Answer 12

* normal minute volumes can generally be achieved with only modest decreases in TV and increases in rate, so NORMOCAPNOEA can usually be maintained

Answer 13

1. _DRY UP FIRST_ * Atropine 1.2mg O with a sip 1/24 prior * Glyco 200 IV on arrival 2. _SEDATE AS NEEDED_ * Fentanyl 75-100 mcg, not Midaz (Currie) 3. _TOPICALISE ORAL_ 1. _Gargle_ 4% Lignocaine 2. consider _cricoid puncture_ 3. Load _DeVilbiss_ with 10mls 4% Lignocaine and 5 lpm * spray 2m back of throat (til gag lost) * spray 2m around corner (till voice change) * use _reversed guedel_ between molars as bite block and proceed 4. _IF NASAL_ 1. as above, plus topicalise nose with atomizer or buds 2. use 6.0 and just feed scope to start 3. stand in front, keep tight, advance under constant vision

Answer 14

* _TYPE 1_ Respiratory Failure = _HYPOXIC_, and is generally due to: * Shunt/V/Q mismatch * Hypoventilation\* * _TYPE 2_ Respiratory Failure = _HYPERCAPNOEIC_, and is generally due to: * hypoventilation. ## Footnote *\* hypoventilation increases alveolar CO2, 'crowding out' oxygen*

ANAESTHESIA A (38) Flashcards

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