2010.1 Flashcards
MC157 [Mar10] [Aug10]
An 18 yo with Fontan Circulation undergoing exploratory laparotomy. On ICU ventilation, saturation is 70%. Which ventilator parameter would you INCREASE to improve his saturation?
A. Bilevel pressure B. Expiratory time C. Inspiratory time D. Peak inspiratory pressure E. PEEP
B. Expiratory time
(Short inspiratory time, long expiratory time - minimise proportion of respiratory cycle where venous return is compromised)
SC33 [Mar10] [Aug10]
A 7 kg Infant with tetralogy of Fallot, post Blalock-Taussig aortopulmonary shunt. Definitive repair at later date. Paralysed and ventilated. Baseline saturation 85%, now 70%, BEST treatment:
A. Increase FiO2 from 50 to 100% B. Esmolol 70mcg C. Phenylephrine 35mcg D. Morphine 1mg E. 1/2 NS with 2.5% dextrose
C. Phenylephrine 35 mcg (PE dose 2-10 mcg/kg)
Increasing systemic pressures will also increase blood flow through the systemic to pulmonary shunt, thereby increasing pulmonary blood flow.
Increasing FiO2 does little to overcome a right to left shunt.
Beta blockers reduce RV contractility (and may help to reduce dynamic RVOT obstruction) but 70 mcg is too small a dose (usual initial dose 0.5 mg/kg).
Volume expansion may help, but would use pressors first (also would not use hypotonic solution)
MH59 [Mar10] [Aug10]
70 year old post TKJR. On sub-cut heparin. Develops clinical DVT and platelets 40 (sounds like HITS type-II). Management
A. Enoxaparin B. Fondaparinux C. Heparin by infusion D. Lepirudin E. Warfarin
D. Lepirudin (N.B. this drug is no longer produced) - use any other direct thrombin inhibitor (e.g.
Lepirudin - indication (MIMS): Treatment of acute heparin induced thrombocytopenia (HIT) type II patients with thrombocytopenia or thromboembolic complications
Enoxaparin, fondaparinux and heparin can all cause HITS (fondaparinux is chemically related to heparin)
There is evidence to suggest that warfarin induced venous limb gangrene may be associated with HIT (MIMS)
Heparin-induced thrombocytopenia (HIT) (eTG)
• An uncommon but dangerous complication of heparin therapy that is characterised by thrombocytopenia and the development of arterial and venous thrombosis. HIT is immune-mediated, and the diagnosis must be confirmed by laboratory demonstration of a specific antibody. HIT is associated with a very high incidence of symptomatic thrombosis, even following discontinuation of heparin. For confirmed HIT, it is therefore imperative to discontinue heparin and start an alternative anticoagulant. As heparin is present in many devices such as syringes and catheters, it is important that heparin is not inadvertently administered in this way to patients with HIT. Low molecular weight heparin can cross-react with the HIT antibody, and should not be used. Alternative anticoagulant regimens include danaparoid or lepirudin
• Bivalirudin has been reported in small case series to be effective in HIT. Firm dosing recommendations are not available
• Warfarin should not be used as the sole initial anticoagulant as it can cause skin necrosis in this setting. Warfarin should be commenced once therapeutic anticoagulation with one of the above agents has been established and the platelet count has risen to more than 100 x 109/L. Warfarin should then be administered for at least 1 month, with a target INR of 2 to 3
ME45 [Mar10]
Features of hypercalcaemia include
A. Chvostek’s sign B. C. seizures D. E. Short QT
E. Short QT
Chvostek’s sign and seizures may occur with hypocalcaemia.
The Chvostek sign (also Weiss sign) is one of the signs of tetany seen in hypocalcemia. It refers to an abnormal reaction to the stimulation of the facial nerve. When the facial nerve is tapped at the angle of the jaw (i.e. masseter muscle), the facial muscles on the same side of the face will contract momentarily (typically a twitch of the nose or lips) because of hypocalcemia (ie from hypoparathyroidism, pseudohypoparathyroidism, hypovitaminosis D) with resultant hyperexcitability of nerves (Wikipedia)
MC161 [Mar10] [Aug10]
Drug eluting stent 6 months old. On aspirin and prasugrel 10mg. Elective lap cholecystectomy for biliary colic.
A. Do case while taking both
B. Do case while stopping both
C. Stop Prasugrel for 7 days, keep taking aspirin
D. Stop Prasugrel for some other different time
E. Post-pone for 6 months
E. Postpone for 6 months
see AHA/ACC 2014 guidelines
AM50 [Mar10]
For a person newly diagnosed as MH susceptible, which is true?
A. ?
B. Can have had an uneventful ‘triggering’ anaesthetic
C. Recommended to use an anaesthetic machine which has not had volatiles through it
D. ?
E. There have been case reports of MH occurring up to 48 h post op
B. Can have had an uneventful ‘triggering’ anaesthetic
Previous uneventful anaesthesia with triggering agents does not preclude MH. 75% of MH index cases have had previous anaesthesia prior to their MH crisis (OHA)
Don’t need a ‘virgin’ anaesthetic machine, just need to adequately flush it:
- Remove vaporisers/fresh circuit, reservoir bag & soda lime. Flush machine & ventilator 10L/min oxygen for 10 minutes (Yao & Artusio)
Features of a MH reaction will always be present before the discontinuation of the trigger because of the threshold concentration requirement. They will not start after the trigger is removed. (CEACCP)
MZ80 [Mar10]
ABG pH 7.12, PO2 100, PCO2 65, HCO3 20.3, BE -10. Consistent with?
A. Chronic renal failure B. Malignant hyperthermia C. Diabetic ketoacidosis D. End-stage respiratory failure E. Ethylene glycol toxicity
B. Malignant hyperthermia (mixed respiratory and metabolic acidosis)
PL30 [Mar10] Maximum dose (with low risk of toxicity) of lignocaine (with adrenaline 1:100000) for liposuction with tumescence technique
A. 3 mg/kg B. 7 mg/kg C. 15 mg/kg D. 25 mg/kg E. 35 mg/kg
E. 35 mg/kg
eMedicine
• In 1987, Jeffery Klein, a dermatologist, first created the technique of tumescent anesthesia in liposuction procedures. Tumescent anesthesia is based on the use of dilute solutions of lidocaine (0.05-0.1%) in large volumes to provide superior anesthesia. Epinephrine (1:1,000,000) is added for hemostasis, and the solution is buffered with sodium bicarbonate to decrease injection discomfort. Concentrations as high as 55mg/kg have been used safely with the tumescent technique
• Klein noted that the correct maximum safe dose of lidocaine was never investigated but rather extrapolated from procaine. He showed that infusion of lidocaine, by using the tumescent formula of 0.1% lidocaine with 1:1,000,000 epinephrine, into the subcutaneous tissues of a concentration of 35mg/kg was safe. The maximum plasma level that was reached at 11-15 hours postoperatively was 0.8-2.7mcg/mL, well below the toxic level of 5mcg/mL. Tumescent anesthetic produces a delay in achieving the peak serum lidocaine level and does not produce as high a level compared with conventional local anesthetic
TMP-100 [Mar10] [Aug10]
Compared to lignocaine, bupivacaine is
A. Twice as potent B. Three times as potent C. Four times as potent D. Five times as potent E. Same potency
C. Four times as potent
TMP-101 [Mar10]
Aneurysm sugery. Propofol / remifentanil / NDMR. DOA monitoring (Entropy). MAP 70 , HR 70/min, State entropy 50, Response entropy 70. What do you do?
A. B. Metaraminol C. Check TOF D. Nothing E. Increase TCI
C. Check TOF
TMP-114 [Mar10]
Paralysed with atracurium. TOF is 1(25%). You give a dose of 0.1 mg/kg mivacurium to close the abdomen. When will you be back to TOF 1(25%)?
A. 5 min B. 10 min C. 30 min D. 60 min E. 90 min
C. 30 mins
Interactions between mivacurium and atracurium (BJA 1994):
• After an initial intubating dose of atracurium, and spontaneous recovery of the first twitch (T1) to 10% of its control height, a maintenance dose of 0.1mg/kg of mivacurium resulted in a time of 25 minutes to regain T1=10%
Plenum Vaporiser
A. ? something with fresh gas flows
B. Relies on a constant flow of pressurised gas C. Out of circle something
D. Not temperature compensated
E. volatile injected into fresh gas flow?
B. Relies on a constant flow of pressurised gas
Upstream gas source required to push fresh gas through the vaporizer (opposite to drawover vaporizer)
Plenum vaporisers are generally out of circle (to protect the circuit from dramatic changes in vapour concentration in the event of pressure surges)
Plenum vaporisers are temperature compensated
Some vaporisers do inject volatile (eg Desflurane Tec 6), but this is a dual-circuit gas-vapour blender not a plenum vaporiser
Anaesthesia UK
• Most vaporisers are of the plenum type, which consists of a vaporising chamber containing the liquid anaesthetic, and a bypass. Gas passing through the vaporising chamber volatilises the anaesthetic and is then mixed with the anaesthetic-free gas bypassing the chamber, the proportion of vapour-containing gas and bypass gas being controlled by a tap
Wikipedia
• The plenum vaporiser is driven by positive pressure from the anaesthetic machine, and is usually mounted on the machine. The performance of the vaporiser does not change regardless of whether the patient is breathing spontaneously or is mechanically ventilated. The internal resistance of the vaporiser is usually high, but because the supply pressure is constant the vaporiser can be accurately calibrated to deliver a precise concentration of volatile anaesthetic vapour over a wide range of fresh gas flows. The plenum vaporiser is an elegant device which works reliably, without external power, for many hundreds of hours of continuous use, and requires very little maintenance
• A plenum vaporiser can only work one way round: if it is connected in reverse, much larger volumes of gas enter the vaporising chamber, and therefore potentially toxic or lethal concentrations of vapour may be delivered. (Technically, although the dial of the vaporiser is calibrated in volume percent (e.g. 2%), what it actually delivers is a partial pressure of anaesthetic agent (e.g. 2kPa))
• The performance of the plenum vaporiser depends extensively on the saturated vapour pressure of the volatile agent. This is unique to each agent, so it follows that each agent must only be used in its own specific vaporiser. Several safety systems have been devised so that filling a plenum vaporiser with the wrong agent is extremely difficult. A mixture of two agents in a vaporiser could result in unpredictable performance from the vaporiser
• Saturated vapour pressure for any one agent varies with temperature, and plenum vaporisers are designed to operate within a specific temperature range. They have several features designed to compensate for temperature changes (especially cooling by evaporation). They often have a metal jacket weighing about 5 kg, which equilibrates with the temperature in the room and provides a source of heat. In addition, the entrance to the vaporising chamber is controlled by a bimetallic strip, which admits more gas to the chamber as it cools, to compensate for the loss of efficiency of evaporation
TMP-102 [Mar10] [Aug10]
Interscalene block, patient hiccups…where do you redirect your needle?
A. Anterior B. Posterior C. Caudal D. Cranial E. Superficial
B. Posterior
OHA:
Phrenic nerve stimulation indicates that the needle is too anterior (on scalenus anterior)
TMP-103 [Mar10] [Aug10]
What is the SVR in a patient with MAP 100mmHg, CVP 5, PCWP 15, CO 5L/min?
A. ?0.8 B. ?3 C. 520 D. 1280 E. 1520 dynes.sec/cm-5
E. 1520 dynes.sec/cm-5
SVR = (MAP - CVP) / CO x 80 = (100 - 5) / 5 x 80 = 1520dynes.sec/cm5
TMP-111 [Mar10]
Accidentally cannulate carotid artery with 5 lumen 7 Fr CVC preop for a semi urgent CABG. Most appropriate next response is to
A. Get vascular surgeon to repair it and continue with surgery and heparin
B. Leave it in. Do CABG. Pull it out post op
C. Pull it out, compress. Delay surgery for 24hrs
D. Pull it out compress. Continue with surgery + heparin
E. Pull it out. Compress. Continue with surgery no heparin
A. Get vascular surgeon to repair it and continue with surgery and heparin
or
C. Pull it out, compress, delay surgery fro 24 hours
(depending on the urgency of surgery)
TMP-115 [Mar10]
Patient for total knee replacement under spinal anaesthetic. Continuous femoral nerve catheter put in for post op pain relief. Good analgesia and range of motion 18hrs post op. 24hrs post op, patchy decreased sensation in leg and unable flex knee. What is the cause?
A. Compression neurapraxia (i think it said due to tourniquet) B. DVT C. Muscle ischaemia D. Damage to femoral nerve E. Spinal cord damage
A. Compression neuropraxia (due to tourniquet)
Nerve injury resulting from tourniquets range from paraesthesiae to complete paralysis. Sciatic nerve injury has been reported with lower limb tourniquets (Anaesthesia 2001)
“Post-tourniquet syndrome” is characterised by stiffness, pallor, weakness without paralysis, and subjective numbness of the extremity without objective anaesthesia
Spinal cord damage probably more likely to result in bilateral pathology
TMP-106 A 75yo male with moderate aortic stenosis (valve area 1.1cm2). Gets mild dyspnoea on exertion but otherwise asymptomatic, needs hip replacement.
A. Continue with surgery B. Beta block then continue C. Get myocardial perfusion scan D. Postpone surgery awaiting AVR E. Postpone surgery awaiting balloon valvotomy
A. Continue with surgery, or
C. Myocardial perfusion scan
Need to evaluate the degree of his functional limitation. If he can do > 4 METs and his symptoms are stable, would probably just crack on and do the hip replacement.
If his exercise capacity is poor or inaccessible, or if his dyspnoea has been getting worse, need to find the reason. He may also have coronary artery disease.
Moderate AS alone is not an indication for surgery, even with symptoms.
However, moderate AS in a patient requiring CABGs is an indication for AVR.
Class 1 indications for AVR:
- Symptomatic patients with severe AS
- Severe AS undergoing CABG
- Severe AS undergoing surgery on the aorta or on the other valves
- Severe AS and LV systolic dysfunction (EF
TMP-112 (similar to above) Patient for fempop bypass, history of CCF. Also has diabetes on oral hypoglycaemics, controlled hypertension and atrial fibrillation at rate of 80bpm .
A. Medium risk surgery, medium risk patient
B. Medium risk surgery, high risk patient
C. High risk surgery low risk patient
D. High risk surgery, medium risk patient
E. High risk surgery, high risk patient.
D. High risk surgery, medium risk patient
RH35 (NEW)
23.Best Approach for a Sub-Tenon’s block?
a. inferonasal
b. inferotemporal
c. medial canthus
d. superior nasal
e. superior temporal
A. Inferonasal
TMP-107 Baby with TracheoOesophageal Fistula found by bubbling saliva and nasogastric tube coiling on xray. Best immediate management?
A. Bag and mask ventilate
B. Intubate and ventilate
C. position head up, insert suction catheter in oesophagus (or to stomach?)
D. Place prone, head down to allow contents to drain
E. Insert gastrostomy
C. Head-up, suction catheter into blind ending
Neonates with TOF should have a “nasogastric” tube inserted into the oesophageal stump to drain secretions and prevent accumulation in the blind-end pouch. The NGT should be connected to continuous suction. The infant should be nursed prone or in the lateral position with 30 degrees head up tilt to decrease the risk of aspiration. See A Practice of Anesthesia for Infants and Children - 4th edition by Cote, Lerman, Todres; p.755. Saunders (2009)
TMP-108 A 60yo Man with anterior mediastinal mass, during induction for mediastinoscopy….lose cardiac output, decreased saturations, drop in ETCO2. Management
A. Adrenaline
B. CPR
C. CPB
D. Place prone
D. Place prone
TMP-116 Post thyroidectomy patient, patient in PACU for 30 minutes. Develops respiratory distress. Most likely cause?
A. Hypercalcemia from taking parathyroids B. Bilateral laryngeal nerve palsies C. bleeding and haematoma D. Tracheomalacia E.
C. Bleeding/haematoma
30 mins after arrival in PACU, so neck swelling (bleeding/oedema) most likely cause.
If it was immediately post-extubation, you would think of tracheomalacia or bilateral laryngeal nerve palsies
TMP-109 MAIN indication for biventricular pacing is
A. complete heart block
B. congestive cardiac failure
c. VF
D.
B. Cardiac failure
AHA/ACC/HRS 2008 guidelines:
- Cardiac resynchronisation therapy: LVEF 120 ms, + NYHA III or IV despite optimal medical therapy
Bivent pacing: one lead in the RV to pace the interventricular septum, other lead in the coronary sinus which can pace the LV lateral free wall.
EV18 Desflurane TEC6 vaporiser, unable to turn dial on. This is NOT because
A. vapouriser is tilted B. Hotter than 39C C. On battery power D. Interlock not engaged, or not seated properly (or something like that) E. other vapouriser is already on
B. Hotter than 39C
• The TEC 6 desflurane vaporizer needs to warm up and the “operational” LED light needs to be illuminated before you can turn the dial to the ON position. If you try to turn it on before the “operational” light is on it will not work
According to Graham (BJA 1994; 72:470-73), causes of vaporizer shutdown include:
• a tilt of about 10 degrees or more - although extremely unlikely given the design
• power failure. It will not work on battery power.
• the vaporizer will not work unless locked into the selectatec mount, and the selectatec mount will not allow the use of multiple vaporizers simultaneously
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