2010.2 Flashcards
TMP-Jul10-001 Pre-eclamptic woman, BP 170/110, headache, proteinuria 1.2g. Which of the following NOT to use for control of her hypertension:
A. Magnesium B. SNP C. GTN D. Hydralazine E. Metoprolol
A. Magnesium
(Mg used for seizure prophylaxis, not for control of BP)
ANZCA says that SNP should be used only as “last resort”, and specifically states “MgSO4 does not reverse or prevent the progression of the disease, nor does it significantly lower BP and it is not recommended as an antihypertensive agent”
Medscape:
In a severe hypertensive emergency, when the above-mentioned medications (hydralazine, labetolol, nifedipine) have failed to lower BP, sodium nitroprusside may be given. Nitroprusside results in the release of nitric oxide, which in turn causes significant vasodilation. Preload and afterload are then greatly decreased. The onset of action is rapid, and severe rebound hypertension may result. Cyanide poisoning may occur subsequent to its use in the fetus. Therefore, sodium nitroprusside should be reserved for use in postpartum care or for administration just before the delivery of the fetus.
The basic principles of airway, breathing, and circulation (ABC) should always be followed as a general principle of seizure management.
Magnesium sulfate is the first-line treatment for the prevention of primary and recurrent eclamptic seizures. For eclamptic seizures that are refractory to magnesium sulfate, lorazepam and phenytoin may be used as second-line agents.
Hypertens Pregnancy. 2004;23(1):37-46.
The effect of glyceryl trinitrate on hypertension in women with severe preeclampsia, HELLP syndrome, and eclampsia.
In women with severe preeclampsia, eclampsia, and HELLP syndrome, infusion of GTN can be used as an alternative agent to well-known drugs and causes no significant adverse effect to the mother and fetus.
TMP-Jul10-002 Male with a Haemoglobin of 8 g/L and reticulocyte count 10%. Possible diagnosis:
A. Untreated pernicious anaemia B. Aplastic anaemia C. Acute leukaemia D. Anaemia of chronic disease E. Hereditary spherocytosis
E. Hereditary spherocytosis
Raised reticulocyte - usually indicates haemolysis
Normal reticulocyte count is 0.5-1.5%
The reticulocyte count is a good indicator of bone marrow activity.
Abnormally low numbers of retics can be attributed to chemo, aplastic anaemia, pernicious anaemia, bone marrow malignancies, decreased EPO, deficiencies (B12, folate, iron), anaemia of chronic disease….
When there is increased production of red cells to overcome loss (eg haemolytic anaemia), reticulocyte count is high.
TMP-Jul10-003 Commonest organism causing meningitis post spinal:
A. Staph epidermidis B. Staph salivarius C. Staph aureus D. Strep pneumoniae E. ?
B. Staph salivarius
IATROGENIC MENINGITIS AFTER SPINAL ANESTHESIA Acta Medica Iranica 2008; 46(5): 434-436.
Various strains of viridans streptococcus (a mouth commensal) are the dominant causative organism in post dural puncture meningitis (PDPM); other causal organisms found in PDPM include Staphylococcus aureus, Pseudomonas aeruginosa, and Enterococcus faecalis. However, in 36% of patients, no organism was isolated or reported.
Bacterial Meningitis After Intrapartum Spinal Anesthesia — New York and Ohio, 2008–2009 Centres for Disease Control and Prevention
Potential sources of bacterial introduction into the intrathecal space during spinal procedures include intrinsic or extrinsic contamination of needles, syringes, or injected medications; inadequately decontaminated patient skin; inadequately cleaned health-care provider hands; a contaminated sterile field; and droplet transmission from the health-care provider’s upper airway. S. salivarius and other viridans group streptococci, which are normal mouth flora, are the most commonly identified etiologies of meningitis after spinal procedures, accounting for 49% and 60% of cases in two literature reviews (2,6). Droplet transmission of oral flora has been suggested as the most likely route of transmission in reports of clusters associated with a single health-care provider (7,8).
In epidural abscess, the most common causative organism is Staph aureus.
TMP-Jul10-004 Exponential decline / definition of time constant (with various options)
A. time for exponential process to reach log(e) of its initial value
B. Time until exponential process reaches zero
C. Time to reach 37% of initial value
D. Time to reach half if its initial value
E. 69% of half life
C. Time to reach 37% of initial value
From BB:
Time constant is the time taken for the concentration/amount of something to fall to 1/e of the initial concentration/amount. The number “e” equals 2.718281828. 1/e = 0.368. Therefore the time constant is the time it takes for the concentration/amount to fall to 36.8% of the initial value (approx 37%). Clearly the time constant is longer than the half life, and there is a formula relating the two: half life = log(e)2 x time constant; thus half life = 0.693 x time constant.
TMP-Jul10-005 (This is a very old repeat) Relative humidity: air fully saturated at 20 degrees. What is the relative humidity at 37 degrees ?
A. 20 B. 30 C. 40 D. 50 E. 60%
C. 40%
From BB: “1m3 of air at 20˚C, 100% saturated, contains about 17g of water. If it is warmed to 37˚C, the mass of water vapour (or absolute humidity) is still the same but the relative humidity is only 39%. At 37˚C, 1m3 of air contains 44g of water vapour when fully saturated and the ratio of 17 to 44 gives a value of 39%.”
TMP-Jul10-006 A 50 year old man with multiple fractures. The BEST parameter to monitor volume resuscitation is:
A. Heart rate B. LVEDV C. PCWP D. RVEDV E. Changes in R atrial pressure during inspiration
E. Changes in R. atrial pressure during inspiration
From Stanford uni echo site:
Static indices
Central venous pressure (CVP), left ventricular end-diastolic area, E/Ea and wedge pressure are indicators of ventricular filling, but do not reliably predict volume responsiveness.
Ideally, the volume status is a “functional assessment”: to induce a change in cardiac preload and observe the effects on cardiac output and arterial pressure.
How to assess the hemodynamic response to volume challenge?
The objective is to distinguish responders (=patients who will benefit from volume expansion) from non-responders (=patients for whom volume expansion may be deleterious).
Clinical parameters can be used: blood pressure, heart rate, urine output… but are not sensitive nor specific.
1. If the ventricles are still pre-load dependant (steep portion of Frank-Starling curve), increase in right ventricle filling will lead to increased right ventricle output, which will increase the left ventricle filling and output. Thus the cardiac output will follow the variations in venous return, leading to respiratory variations of stroke volume.
It has been validated (5) that respiratory variations > 20% of stroke volume predict positive hemodynamic response to volume expansion. VTI or maximum velocity of LVOT flow can be used as surrogates of stroke volume.
2. Respiratory variations of IVC diameter will be observed only in patients in whom the right atrial pressure is not high, indicating right ventricle pre-load dependence. IVC diameter respiratory variations can therefore predict the hemodynamic response to volume challenge (6-7):
▪ respiratory variations of IVC diameter are greater in patients who will respond to fluid expansion
▪ after fluid infusion, respiratory variations of IVC diameter decreased significantly in these patients
▪ small IVC (
TMP-Jul10-007 Anaphylaxis to rocuronium. Which is most likely to cause coss-reactivity ?
A. Vecuronium B. Pancuronium C. Atracurium D. Cisatracurium E. None of the above -cross reactivity too variable to predict
A. Vecuronium
(from BJA paper 2013):
Anaphylaxis to roc –> cross reactivity to sux > vec > atrac > panc > cisatrac
Suspected anaphylactic reactions associated with anaesthesia. Anaesthesia 2009
Cross-sensitivity between different NMBAs is relatively common, probably because they share a quaternary ammonium epitope. If anaphylaxis to an NMBA is suspected, the patient should undergo skin prick testing with all the NMBAs in current use. If a patient demonstrates a positive skin prick test (SPT) to an NMBA, the patient should be warned against future exposure to all NMBAs if possible. If it is mandatory to use an NMBA during anaesthesia in the future, it would seem appropriate to permit the use of an NMBA which has a negative skin test, accepting that a negative skin test does not guarantee that anaphylaxis will not occur.
Allergy 2007; 62: 471-487 Review Article: Anaphylaxis during anaesthesia: diagnostic approach “Cross Reactivity between NMBA is said to be common because of ubiquitous ammonium groups in these drugs. The estimated prevalence of cross-reactivity between NMBA is about 65% by skin tests and 80% by radioimmuno assay inhibition tests. While some pairings are common, the patterns of cross-reactivity vary considerably between patients.”
TMP-Jul10-008 Hypotension post propofol induction in elderly patient. More pronounced / profound than in younger patient. Reason ?
A. Concentric LVH associated with ageing and therefore preload dependent
B. Because of increased lean body mass
C. Decreased cardiac output with ageing
D. Increased sensitivity to all anaesthetic agents, thus relative overdose is common
E. Decreased liver blood flow with ageing, decrease drug clearance and increased drug concentration
A. Concentric LVH associated with ageing and therefore preload dependent.
?D also correct (increased sensitivity to all anaesthetic agents)
Geriatric Anesthesiology, Rooke et al (google books)
“The brain becomes more sensitive to propofol with increasing age; Schnider et al reported that geriatric patients were approximately 30% more sensitive to pharmacodynamic effects of propofol than younger subjects, as measured by EEG changes.
The degree of hypotension is increased…in the geriatric patient, by several mechanisms. First propofol impairs the arterial baroreceptor reflex to hypotension, which is already decreased in the geriatric patient. Second, the geriatric patient is more likely to have ventricular dysfunction. A decrease in preload in these patients may result in a significant decrease in cardiac output…
TMP-Jul10-009 Predictive factors for mortality in elderly patient (except):
A. Aortic stenosis B. Diabetes mellitus C. Elevated Creatinine D. Cognitive dysfunction E. Type of surgery
???
Lots of references… all seem to have been shown to be associated with increased mortality by various people.
Am J Med. 2004 Jan 1;116(1):8-13.
Aortic stenosis: an underestimated risk factor for perioperative complications in patients undergoing noncardiac surgery
Aortic stenosis is a risk factor for perioperative mortality and nonfatal myocardial infarction, and the severity of aortic stenosis is highly predictive of these complications.
Minimizing perioperative adverse events in the elderly, BJA 2001
Predictive factors:
The function capacity of organs reduces with ageing, resulting in decreased reserve and ability to endure stress. Advanced age is, therefore, a significant risk factor for increased mortality. Co‐existing disease further depresses organ function and/or reserve, exacerbating risk. For example, pre‐existing hypertension, diabetes mellitus, or renal failure contributes to a higher incidence of perioperative myocardial infarction (MI) (5.1%), cardiac death (5.7%) or ischaemia (12–17.7%). Additional risk factors in the elderly include the need for emergency surgery, major surgical procedures, ASA physical status III or IV, and poor nutritional status.
The elderly surgical patient 2008
In 1999, Lee and colleagues developed a simplified index known as the Revised Cardiac Risk Index (RCRI), which included six variables that had been found to be independent predictors of cardiac complications. In the RCRI, one point is given for each of the following cardiac risk factors: (1) a history of CHF, (2) a history of ischemic heart disease, (3) a history of cerebrovascular disease, (4) preoperative treatment with insulin, (5) a preoperative serum creatinine level higher than 2.0 mg/dl, and (6) a high-risk surgical procedure.
Preoperative cognitive dysfunction has been associated with increased postoperative complications and worse survival in elderly surgical patients. Such dysfunction may take the form of either dementia or delirium. Dementia is a chronic baseline impairment of cognitive function. Demented patients are known to experience higher postoperative mortality than patients with intact cognitive function. Delirium is an acute confusional state associated with multiple possible causes. The incidence of postoperative delirium in older patients ranges from 20% to 60%. This state is associated with a prolonged hospital stay, functional decline, and increased mortality. Risk factors for the development of postoperative delirium include preexisting dementia, visual impairment, alcohol consumption, infection, narcotic use, and polypharmacy.
Complications and mortality in older surgical patients in Aus and NZ (the REASON study), Anaesthesia, 2010 (K Leslie et al)
Pre-operative factors associated with mortality included: increasing age (80-89 years: OR 2.1 (95% CI 1.6-2.8), p
TMP-Jul10-010 The best clinical indicator of SEVERE AS
A. Presence of thrill B. Mean Gradient 30mmHg C. Area 1.2 cm2 D. Slow rising pulse and ESM radiating to carotids E. Shortness of breath
A. Presence of a thrill
TMP-Jul10-011 Elderly patient. Indications for pre Femoro-Popliteal Bypass coronary angiogram include all EXCEPT:
A. Severe heart failure B. Suspicion of L main disease C. Symptomatic tachyarrhythmia D. Unstable angina E. Stable angina with positive thallium
? C. Symptomatic tachyarrhythmia
AHA/ACC 1999
Recommendations for Coronary Angiography in Perioperative Evaluation Before (or After) Noncardiac Surgery:
Class I: Patients with suspected or known CAD
- Evidence for high risk of adverse outcome based on noninvasive test results. (Level of Evidence: C)
- Angina unresponsive to adequate medical therapy. (Level of Evidence: C)
- Unstable angina, particularly when facing intermediate or high-risk noncardiac surgery. (Level of Evidence: C)
- Equivocal noninvasive test result in a high-clinical-risk patient undergoing high-risk surgery. (Level of Evidence: C)
Class IIa
- Multiple intermediate-clinical-risk markers and planned vascular surgery. (Level of Evidence: B)
- Ischemia on noninvasive testing but without high-risk criteria. (Level of Evidence: B)
- Equivocal noninvasive test result in intermediate-clinical-risk patient undergoing high-risk noncardiac surgery. (Level of Evidence: C)
- Urgent noncardiac surgery while convalescing from acute MI. (Level of Evidence: C)
Class IIb
- Perioperative MI. (Level of Evidence: B)
- Medically stabilized class III or IV angina and planned low-risk or minor surgery. (Level of Evidence: C)
TMP-Jul10-012 How do you minimise risk of intravenous cannulation with epidural insertion?
A. Injection saline through epidural needle before catheter insertion B. Lie patient lateral C. Do CSE D. Thread catheter slowly E.
A. Injection of saline through epidural needle before catheter insertion (OR 0.53)
B. Lie patient lateral (OR 0.49)
(Systematic review, Anesth Analg 2009)
TMP-Jul10-013 Timing of peak respiratory depression post intrathecal 300 mcg morphine:
A. 18 hours
B. 3.5-7.5 h
ANZCA Acute Pain: Scientific Evidence 3rd ed:
“Respiratory depression occurs in up to 1.2% to 7.6% of patients (Meylan et al, 2009 Level I) given intrathecal morphine. When measured in opioid-naive volunteers, respiratory depression peaked at 3.5 to 7.5 hours following intrathecal morphine at 200 to 600 mcg doses (Bailey et al, 1993 Level IV). Volunteers given 600 mcg had significant depression of the ventilatory response to carbon dioxide up to 19.5 hours later.
TMP-Jul10-014 Patient with aortic dissection. Blood pressure 150/90. Best drug to control BP:
A. Captopril B. Esmolol C. GTN D. Hydralazine E. SNP
B. Esmolol
(reduces force of LV contraction)
If beta-blocker alone not sufficient to control BP, add vasodilator
TMP-Jul10-015 Type of dissection – which is classically for NON-operative management:
A. DeBakey Type I B. DeBakey Type II C. Stanford A D. Stanford B E. Stanford C
C. Stanford A
Stanford classification
Type A — dissection extends to arch/ascending aorta –> needs operative repair
Type B — dissection of the descending aorta only (distal to L. subclavian artery) –> medical management with BP control
De Bakey classification
Type 1 — dissection of the entire aorta
Type 2 — dissection of the ascending aorta
Type 3 — dissection of the descending aorta
TMP-Jul10-016 TURP – patient under spinal. Confused. ABG: Na+ 117 / normal gas exchange. Treatment ?
A. 10 ml 20% Saline as fast push IV B. 3% NS 100 ml/h C. Normal saline 200 ml/h D. Frusemide 40 mg IV E. Fluid restrict 500 ml/day
B. 3% saline 100 mL/h
1.2-2.4ml/kg/hr of 3% saline until symptomatic improvement (this rate should increase serum Na+ by 1-2 mmol/h)
TMP-Jul10-017 Male undergoing trans-sphenoidal surgery. Now Na+ 155mmol/l and thirsty with polydipsia. Treatment:
A. Desmopressin (DDAVP) B. Fluid restrict C. Aldosterone D. E.
A. DDAVP
TMP-Jul10-018 The STRONGEST stimulus for ADH secretion:
A. High serum osmolality B. Low serum osmolality C. Hypovolaemia D. High serum Na E.
C. Hypovolaemia
From BB:
Osmoreceptor control is very sensitive, responding to 1-2% changes in plasma osmolality.
If hypovolaemia is present, this will ‘over-ride’ osmoreceptor control. Thus it is commonly said that volume is maintained at the expense of osmolality, or equivalently, that hypovolaemia will result in an increase in ADH level despite the inhibitory effect of hypo-osmolality.
The actual plasma levels that occur with hypovalaemia are much higher that those occurring with hyperosmolality, so volume control (of ADH secretion) is less sensitive, but much more powerful.
TMP-Jul10-019 Stellate ganglion block. Needle entry next to SCM muscle at C6. Which direction to advance needle ?
A. C3 B. C4 C. C5 D. C6 E. C7
D. C6
The patient is placed in the supine position with the neck slightly extended, the head rotated slightly to the side opposite the block, and the jaw open. The point of needle puncture is located between the trachea and the carotid sheath at the level of the cricoid cartilage and Chassaignac’s tubercle. Although the ganglion lies at the level of the C7 vertebral body, the needle is inserted at the level of C6 to avoid the piercing the pleura. Cutaneous anaesthesia is obtained with a skin wheal of local anaesthetic.
The sternocleidomastoid and carotid artery are retracted laterally as the index and middle fingers palpate Chassaignac’s tubercle. The skin and subcutaneous tissue are pressed firmly onto the tubercle to reduce the distance between the skin surface and bone, and in an attempt to push the dome of the lung out of the path of the needle. When properly performed, this manoeuvre is uncomfortable for the patient.
The needle is directed onto the tubercle, and then redirected medially and inferiorly toward the body of C6. After the body is contacted, the needle is withdrawn 1-2 mm. This brings the needle out of the belly of the longus colli muscle, which sits posterior to the ganglion and runs along the anterolateral surface of the cervical vertebral bodies. The needle is then held immobile.
Needle position is confirmed by fluoroscopy. Spread of radiocontrast is confirmed by both anteroposterior and lateral views. Failure of the solution to spread cephalad and caudad between tissue planes suggests intramuscular injection into the longus colli muscle. Immediate dissipation of the solution indicates intravascular placement of the needle orifice.
TMP-Jul10-020 20. Thermoneutral zone in 1 month old infant ?
A. 26 – 28 degrees Celcius B. 28 – 30 degrees Celcius C. 30 – 32 degrees Celcius D. 32 – 34 degrees Celcius E. 34-46 degrees celcius
C. 30-32C
(Term neonate has TNZ of 32-34C; TNZ is higher from premature neonates)
Thermoneutral zone = ambient temperature where minimal O2 consumption is required to maintain core temperature
Paediatric Surgery, diagnosis and management, 2009:
- Infants weighing 2 – 3kg have a TNZ of 31-34C at birth and 29-31C at 12 days.
Public Health Nutrition: 8(7A), 953–967
- In the first 24 hours after birth, this temperature is 34–36C for the naked infant and falls to 30–32C by 7–10 days of age.
TMP-Jul10-021 A 60 year old man describes orthopnoea. On examination: pansystolic murmur (at LSE)/ displaced apex beat. Likely diagnosis ?
A. Mitral regurgitation B. ? C. D. E.
A. Mitral regurgitation
TMP-Jul10-022 A 4 year old child with VSD (repaired when 2 years old) for dental surgery. What antibiotic prophylaxis do the guidelines recommend?
A. Amoxycillyn orally B. Amoxycillin IV C. Cephazolin IV D. Amoxycillin / gentamicin E. No antibiotics required
E. No antibiotics required
TMP-Jul10-023 A 4 year old child with Arthrogrophysis multiplex congenita for dental surgery. Jaw rigidity post induction. Likely cause?
A. Temporomandibular joint involvement/ TMJ rigidity
B. Inadequate depth of anaesthesia
C. Inadequate muscle relaxation/ inadequate sux
D. Masseter spasm
E. ?
A. TMJ involvement/rigidity
Arthrogryposis Multiplex Congenita is a rare congenital disorder that causes multiple joint contractures and can be associated with muscle weakness and fibrosis. It is a non-progressive disease. Anaesthetic issues include difficult IV access, airway and association with anterior horn cell disease. Although an association with MH has been suggested, this has not been confirmed…
Patients with arthrogryposis have micrognathia, a high arched palate, and a short and rigid neck making tracheal intubation difficult and at times impossible. The primary concern to the anesthesiologist is the potential for airway involvement thereby making direct laryngoscopy and endotracheal intubation difficult.
Direct laryngoscopy and intubation become more difficult as the patient ages because craniofacial involvement often progresses with growth. Alternatives to direct laryngoscopy and tracheal intubation, such as the use of the laryngeal mask airway, with or without the use of a tube exchanger, or fiberoptics, have been used successfully in this disorder. In such difficult airway scenario we decided to avoid intubation and maintained her on spontaneous ventilation. We kept difficult intubation cart ready in case required to secure airway in emergency.
The extensive contractures, tense skin, and minimal muscle mass and subcutaneous tissue pose challenges for intraoperative positioning and intravenous access. Children with arthrogryposis may have altered responses to neuromuscular relaxants and are akin to other patients with anterior horn cell diseases.
Response to nondepolarizing relaxants has been reported to be extremely variable, the use of short-acting nondepolarizing agents in association with careful monitoring of neuromuscular function has been advocated in these patients
TMP-Jul10-024
A 78 year old man with past history of a difficult intubation presents for arm surgery. Supraclavicular block with 25 mls 0.5% bupivacaine. Shortly after begins convulsing. INITIAL management?
A. Midazolam 5mg B. Intralipid 20% 1.5 ml/kg C. Thiopentone 150mg D. Suxamethonium 50mg E. Propofol 50mg
A. Midazolam 5 mg
ASRA Practice Advisory on Local Anesthetic Systemic Toxicity (Regional Anesthesia & Pain Medicine 2010)
• If seizures occur, they should be rapidly controlled to prevent injury to the patient and acidosis. The Panel recommends that benzodiazepines are the ideal drugs to treat seizures because they have limited potential for cardiac depression
(benzos also less likely to cause apnoea than propofol or thiopentone)
