MCQ 24.2 Flashcards
Which of the following is the primary mechanism by which IV magnesium sulfate reduces the risk of eclampsia in pre-eclampsia?
a. Blocking calcium influx at the neuromuscular junction
b. Increasing renal perfusion
c. Inhibiting NMDA receptor activity in the CNS
d. Enhancing nitric oxide release from the endothelium
e. Reducing systemic vascular resistance
Correct Answer:
c. Inhibiting NMDA receptor activity in the CNS
Innervation of the Breast
Which of the following statements about breast innervation is correct?
a. The long thoracic nerve provides motor innervation to the pectoralis major muscle, which underlies the breast.
b. The lateral cutaneous branches of intercostal nerves provide the majority of sensory innervation to the breast.
c. The thoracodorsal nerve provides sensory innervation to the upper outer quadrant of the breast.
d. The supraclavicular nerve supplies the entire breast, including the nipple.
e. The medial cutaneous nerve of the arm contributes to sensory innervation of the nipple.
Correct Answer:
b. The lateral cutaneous branches of T4-T6 intercostal nerves provide the majority of sensory innervation to the breast.
Physiological Changes of Pregnancy
Which of the following best explains the increased susceptibility to hypoxemia in pregnant patients during apnea?
a. Increased tidal volume and respiratory rate
b. Decreased functional residual capacity and increased oxygen consumption
c. Decreased plasma oncotic pressure and increased airway edema
d. Increased cardiac output and decreased hemoglobin concentration
e. Decreased alveolar ventilation and increased dead space
Correct Answer:
b. Decreased functional residual capacity and increased oxygen consumption
Physiology of Hyperthyroidism
Which of the following hemodynamic findings is most characteristic of hyperthyroidism?
a. Increased systemic vascular resistance with normal cardiac output
b. Decreased systemic vascular resistance with increased cardiac output
c. Increased pulmonary artery pressure with decreased stroke volume
d. Increased preload with decreased ejection fraction
e. Decreased preload with normal ejection fraction
Correct Answer:
b. Decreased systemic vascular resistance with increased cardiac output
Mechanism of Action of Low Molecular Weight Heparin
What is the primary mechanism of action of low molecular weight heparin (LMWH)?
a. Inhibition of thrombin (Factor IIa) via direct binding
b. Activation of antithrombin to inhibit Factor Xa
c. Direct inhibition of Factor Xa
d. Inhibition of platelet aggregation via glycoprotein IIb/IIIa receptor blockade
e. Direct activation of the fibrinolytic pathway
Correct Answer:
b. Activation of antithrombin to inhibit Factor Xa
Actions of Hyaluronidase
Which of the following best describes the action of hyaluronidase in regional anesthesia?
a. Increases the lipid solubility of local anesthetics
b. Facilitates the spread of local anesthetics by breaking down interstitial hyaluronic acid
c. Enhances nerve blockade by inhibiting voltage-gated sodium channels
d. Prolongs the duration of nerve blockade by reducing local blood flow
e. Acts as a vasoconstrictor to decrease systemic absorption of local anesthetics
Correct Answer:
b. Facilitates the spread of local anesthetics by breaking down interstitial hyaluronic acid
Pacemaker Code
In a pacemaker with the code VVI, what does the second “V” represent?
a. The mode of pacing
b. The mode of sensing
c. The response to sensing
d. The location of the lead placement
e. The type of rhythm detected
Correct Answer:
b. The mode of sensing
Which of the following is most likely to cause interference with pulse oximetry readings?
a. Hypothermia
b. Carbon monoxide poisoning
c. Anemia with hemoglobin <7 g/dL
d. Hypoxemia with SpO2 <80%
e. Peripheral vasodilation
Correct Answer:
b. Carbon monoxide poisoning
Mechanism of Action of Low Molecular Weight Heparin
Which of the following is a characteristic of low molecular weight heparin (LMWH) compared to unfractionated heparin (UFH)?
a. Greater inhibition of thrombin (Factor IIa) than Factor Xa
b. Shorter half-life than unfractionated heparin
c. Does not require antithrombin for its action
d. Preferential inhibition of Factor Xa over thrombin
e. Reversible by protamine in a 1:1 ratio
Correct Answer:
d. Preferential inhibition of Factor Xa over thrombin
Actions of Hyaluronidase
Which of the following is a contraindication to the use of hyaluronidase in regional anesthesia?
a. Allergy to local anesthetics
b. Infection at the injection site
c. Concurrent use of vasopressors
d. History of hypertension
e. Use in pediatric patients
Correct Answer:
b. Infection at the injection site
Prognosis After Cardiac Arrest
Which of the following is most strongly associated with survival to hospital discharge after out-of-hospital cardiac arrest?
a. Administration of epinephrine within 5 minutes
b. Initial rhythm of ventricular fibrillation (VF)
c. Use of therapeutic hypothermia post-resuscitation
d. Age under 50 years
e. Normal serum lactate at admission
Correct Answer:
b. Initial rhythm of ventricular fibrillation (VF)
Pacemaker Code
In the pacemaker code DDD, what does the third “D” represent?
a. Dual sensing and pacing in the atrium and ventricle
b. The response to sensing is dual (inhibitory and triggered)
c. Dual lead placement in both atrium and ventricle
d. Default pacing mode in the absence of sensed activity
e. The type of rhythm detected
Correct Answer:
b. The response to sensing is dual (inhibitory and triggered)
Pulse Oximetry Interference
Which of the following conditions is least likely to interfere with pulse oximetry readings?
a. Methylene blue administration
b. Severe peripheral vasoconstriction
c. Elevated carboxyhemoglobin levels
d. Hyperbilirubinemia
e. Severe hypothermia
Correct Answer:
d. Hyperbilirubinemia
Trigeminal Neuralgia Effects
Which of the following is a typical feature of trigeminal neuralgia?
a. Constant dull pain
b. Pain triggered by light touch or chewing
c. Bilateral pain distribution
d. Pain primarily affecting the ophthalmic division
e. Onset after a viral infection
Correct Answer:
b. Pain triggered by light touch or chewing
What is the primary mechanism of heparin-induced thrombocytopenia (HIT)?
a. Direct platelet destruction by heparin
b. Activation of platelets by heparin-antibody complexes
c. Increased platelet clearance by the spleen
d. Inhibition of thrombin by heparin
e. Autoimmune destruction of megakaryocytes
Correct Answer:
b. Activation of platelets by heparin-antibody complexes
Which test is most commonly used to confirm a diagnosis of HIT?
a. Prothrombin time (PT)
b. Platelet function assay
c. Heparin-induced platelet aggregation assay
d. D-dimer levels
e. Anti-factor Xa activity
Correct Answer:
c. Heparin-induced platelet aggregation assay
Which echocardiographic view is most commonly used to assess myocardial ischaemia during surgery?
a. Apical four-chamber view
b. Mid-esophageal long-axis view
c. Transgastric short-axis view
d. Subcostal view
e. Suprasternal view
Correct Answer:
c. Transgastric short-axis view
What is the earliest echocardiographic sign of myocardial ischaemia?
a. Decreased ejection fraction
b. Hypokinesia of the affected wall
c. Appearance of new mitral regurgitation
d. Increased left atrial size
e. Global hypokinesia
Correct Answer:
b. Hypokinesia of the affected wall
What is the primary reason for using high fresh gas flows in paediatric anaesthesia with a Mapleson circuit?
a. To prevent rebreathing
b. To conserve heat and moisture
c. To reduce airway resistance
d. To avoid circuit disconnection
e. To ensure rapid emergence
Correct Answer:
a. To prevent rebreathing
Which Mapleson circuit is considered the most efficient for spontaneous ventilation in children?
a. Mapleson A
b. Mapleson B
c. Mapleson C
d. Mapleson D
e. Mapleson F
Correct Answer:
e. Mapleson A
Which Mapleson circuit is most efficient for controlled ventilation?
a. Mapleson A
b. Mapleson B
c. Mapleson C
d. Mapleson D
e. Mapleson F
Correct Answer:
d. Mapleson D
The most efficient circuit for controlled ventilation because the FGF forces alveolar air away from the patient and towards the APL valve. It’s often used for manual ventilation while transporting patients
The sciatic nerve provides motor innervation to which of the following muscles?
a. Quadriceps femoris
b. Gluteus maximus
c. Biceps femoris
d. Tensor fasciae latae
e. Sartorius
Correct Answer:
c. Biceps femoris
Which of the following is a sensory function of the sciatic nerve?
a. Sensation over the medial thigh
b. Sensation over the lateral thigh
c. Sensation over the sole of the foot
d. Sensation over the posterior thigh
e. Sensation over the medial malleolus
c. Sensation over the sole of the foot
What is the primary mechanism of action of methylene blue in vasoplegia?
a. Inhibition of guanylate cyclase
b. Activation of nitric oxide synthase
c. Inhibition of angiotensin-converting enzyme
d. Direct vasoconstriction of arterioles
e. Enhancement of cyclic AMP
Correct Answer:
a. Inhibition of guanylate cyclase