EDAIC 1 MCQs from the daily-MCQ zone. Weekly free uploads by targetedaic (2).

(a). Hyperkalaemia
(b). Hypokalemia
(d). Hypomagnesemia
(e). Congenital Long QT syndrome
(f). Use of macrolide antibiotics

A. FALSE B. TRUE C. TRUE D. TRUE E. TRUE

A prolonged QTc interval (> 450 msec in men and 460 msec in women as per AHA/ACC) makes the heart vulnerable to dangerous arrhythmias (particularly torsades de pointes with values more than 500 msec) and needs meticulous evaluation.

FACTORS ASSOCIATED WITH A LONG QTC:

1. Congenital (long QT syndrome)
2. Acquired
   1. Electrolyte disturbances (↓K⁺, ↓Ca²⁺, ↓Mg²⁺,)
   1. Myocardial ischaemia, ROSC, cardiac failure
   1. Raised ICP
   1. Hypothermia
   1. Medications
3. Antihistamines and decongestants (Diphenhydramine, Astemizole, Loratadine)
   1. Antibiotics (Chloroquine, Hydroxychloroquine, Quinine, Macrolides: Erythromycin; Clarithromycin)
   1. Antiarrhythmics (Ia, Ic, III)
   1. Tricyclic anti-depressants (Amitriptyline, Doxepin, Imipramine, Nortriptyline)
   1. Antipsychotics (Chlorpromazine, Haloperidol, Droperidol, Quetiapine)

A patient presenting for routine bowel surgery has a history of recurrent, haemodynamically unstable, ventricular tachycardia for which an implantable cardioverter defibrillator (ICD) was inserted two years previously. The device has been checked and the defibrillator function of the icd deactivated prior to surgery:

(a). The placement of external defibrillator pads should be less than 10cm away from the device.
(b). Arrhythmias should be treated conventionally by following standard Advanced Life Support (ALS) procedures.
(d). The energy output for conventional defibrillation should be altered to take account of the presence of the ICD.
(e). External pacing is contraindicated.
(f). The device will need to be checked at the end of surgery..

A. FALSE B. TRUE C. FALSE D. FALSE E. TRUE
ANAESTHETIC CONSIDERATIONS IN THE IMPLANTABLE CARDIOVERTER DEFIBRILLATOR DEVICES:

1. Should be checked within 6 months of surgery.
2. The defibrillator function needs to be deactivated before surgery.
3. The external defibrillator pads should be placed at least 10 cm away from the impulse generator (a minimum distance of 2.5cm is recommended by AHA/ACC) and the current vector should be placed perpendicularly to implanted leads’ vector. THE ANTERO-POSTERIOR placement is recommended for maximum benefit and minimum device damage in patients with left pectoral generator placement.
4. External defibrillator and anti-arrhythmic drugs should be available at the patient bedside till the patient becomes stable and ICD function is restored after surgery.
5. In event of significant arrhythmias, the standard ACLS protocol should be followed.
6. MInimum effective DC shock should be chosen to prevent damage to the device.
7. The device should be checked after surgery and the ICD functionality restored as soon as possible.

For a detailed discussion on the Anaesthetic management of patients with Cardiac Implantable Electronic devices download the “ANAESTHETIC IMPLICATIONS OF THE CARDIAC IMPLANTABLE ELECTRONIC DEVICES (CIEDs)” module.

A. arterial hypotension
B. a decrease in end-tidal carbon dioxide concentration
C. cardiac arrhythmias
D. a decrease in pulmonary vascular resistance
E. a decrease in intracranial pressure

A. True B. True C. True D. False E. False

Anaesthetists may face venous air embolism inside or outside the OT. It is a medical emergency that needs urgent attention, particularly when significant air is involved as the process is ongoing as the severity depends upon the volume as well as the rate of embolism. the lethal volume for VAE is quoted somewhere between 3 to 5 ml/kg. the closer the air entrainment site to RV, the lethal the effect.

THE CARDINAL FEATURES ARE:

Decrease in end-tidal CO2 as the air emboli block the flow in small pulmonary arteries and capillaries. This increases the dead space ventilation as the ventilation remains unhindered while the perfusion drops. The emboli also incite an inflammatory response in the affected segments, which when widespread or severe, can lead to ARDS.

HPE takes over in the involved areas and generalised HPV will occur if the area involved is extensive. This aims to cut off supply from hypoxic units to well-perfused areas. HPV will in turn lead to an increase in the pulmonary artery pressure and the raised PAP adversely affects the right ventricular output and hence the CO.

The sudden rise in right ventricular outflow resistance and fall in CO producing sudden hypotension. Severe VAE can lead to sudden and complete RV outflow obstruction and patient collapse. The sudden cardiac insult along with decreased perfusion can lead to myocardial/cerebral ischaemia, induce cardiac conduction abnormalities and arrhythmias like sinus tachycardia/PACs/RBBB/AF/etc.

To compensate for the fall in blood pressure/CO along with increased outflow resistance due to the increase in CVP (right heart outflow obstruction/ rising PAP) the autoregulation of cranial vasculature will adjust in order to increase the flow. It can be complicated by the direct cerebral air embolism through open foramen ovale. increasing insult increases the potential and severity of cerebral oedema. All this culminates into the rising ICP and the failing cerebral circulation.

Patients with untreated hypothyroidism show

A. resistance to hypnotics
B. depression of cardiac performance
C. high voltage T waves on the ECG
D. increased sensitivity to non-depolarising neuromuscular blocking drugs
E. delayed return of consciousness after anaesthesia

A. False B. True C. False D. True E. True

Hypothyroid patients are highly sensitive to the central nervous system depressants, sedatives, or narcotic analgesics and need very careful and monitored dosing in patients with severe hypothyroidism because significant CNS and respiratory depression may occur. Delayed awakening after GA is a likely consequence, especially in uncontrolled cases.

Decreased level of consciousness may lead to impaired protective airway reflexes and increased likelihood of aspiration of gastric contents.

The major cardiovascular changes that occur in hypothyroidism include a decrease in cardiac output and cardiac contractility. It is a cumulative effect of the reduction in heart rate, decreased arterial compliance, decreased plasma volume, atherosclerosis. and an increase in peripheral vascular resistance. All these factors contribute towards the development of heart failure in hypothyroidism.

Important ECG changes described in hypothyroidism are sinus bradycardia, prolonged QTc interval, changes in
the morphology of the T-wave, QRS duration and low voltage. Tall T waves are not characteristic of hypothyroidism.

Muscle relaxants are generally considered safe in well-controlled hypothyroid patients. Increased sensitivity to NDMR may be seen in presence of hypothermia (Hypothyroidism is associated with an increased likelihood of intraop hypothermia), pre-existing myopathy, decreased hepatic metabolism and renal excretion (as seen in uncontrolled states).

• A. Macrocytic anaemia
• B. Interstitial renal fibrosis
• C. Hypertension
• D. Peripheral neuropathy
• E. Suppression of humoral immunity

A. TRUE B. FALSE C. FALSE D. FALSE E. FALSE

Cyclosporine inhibits calcineurin, which reduces the production of IL-2 via inhibition of nuclear factor of activated T cells (NF-AT). It is used to treat RA, SLE, polymyositis, rejection of transplantMetabolized by CYP 3A4. Monitoring is essential although target levels are institution-specific. Reasonable serum/plasma levels are 150-250 ng/mL at transplantation and 50-100 ng/mL at 3-6 months (or 100-300 and 80-200 ng/mL as measured in whole blood). Daily IV dosing is usually ~ 5 mg/kg in two divided doses, with PO dosing increased about 3-fold. Hypertension and renal injury are major side effects of this drug, neurotoxicity is also problematic.

Side-effects include:

Genitourinary
-renal dysfunction (common 30%)
-glomerular capillary thrombosis

Cardiovascular
-hypertension (50%)
-IHD

Skin
-Acne
-Hirsutism

CNS
-tremor (common 20%)
-convulsion
-headache
-somnolence

GIT
-gum hyperplasia (common 15%)
-diarrhoea
-nausea vomiting (common 10%)
-hepatotoxicity (common 50% of patients have elevated bilirubin, transaminases, alk phoshatase)
-gynecomastia

CNS
-distal plaresthesia
-Flushing

Blood
-leukopenia
-lymphoma
(infectious complications include : sepsis, abscess, systemic fungal infection CMV)

Resp
-sinusitis

• A. has a perioperative stroke rate of 8 to 10%
• B. should be performed under regional anaesthesia in patients with ischaemic heart disease to reduce the incidence of myocardial infarction
• C. may be performed under induced hypotension to reduce intraoperative blood loss
• D. when performed under deep cervical plexus block is often associated with a phrenic nerve palsy
• E. should be performed under regional anaesthesia in patients with a recent transient ischaemic attack to reduce the incidence of peri-operative stroke

A. FALSE B. FALSE C. FALSE D. TRUE E. FALSE

Explanation :

Carotid endarterectomy (CEA) is performed to prevent embolic stroke in patients with atheromatous disease at the carotid bifurcation.

The two most feared major perioperative complications of CEA are cerebrovascular accident and myocardial infarction. Perioperative risk of Stroke in CEA is 3-5% (6.5% if symptomatic, 2.3% if asymptomatic), and that of MI is approx. 2.2%. 

CEA may be carried out under regional or general anaesthesia. The impact of the choice of anaesthesia on the outcome of this operation has been extensively studied and large trials and systematic reviews have shown that the type of anaesthesia does not affect the outcome. There is no evidence for use of regional anaesthesia in cardiac patients.

Deep cervical block and superficial cervical plexus block can be used as regional anaesthesia for CEA. Possible complications of deep cervical block include injection into the CSF with consequent brainstem anaesthesia, arterial injury, intra-arterial injection, and phrenic nerve paralysis resulting in respiratory distress. The deep block should not be performed in anticoagulated patients.

BP should be in normal to high range to reduce cerebral ischemia and stroke.

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