CVP Cannulation Techniques and Circulatory Support Flashcards

What is the purpose of a left ventricular vent during CPB?

Answer: To prevent LV distension by draining bronchial and thebesian venous return

The LV vent drains non-coronary collateral blood (from bronchial and thebesian veins) that continues to enter the arrested LV during bypass, preventing distension and subendocardial injury.

Which is the most important consideration when selecting arterial cannula size?

Answer: Achieving required pump flow at acceptable pressure gradient without excessive velocity

Arterial cannula selection must balance achieving required flow rates within acceptable pressure gradients; undersized cannulas cause excessive velocity, hemolysis, and jetting injury to the aortic wall.

What is the standard method to confirm correct venous cannula placement before initiating full bypass?

Answer: Observing adequate venous drainage combined with TEE visualization of cannula position

Transesophageal echocardiography directly visualizes cannula tip position while observation of adequate gravity or vacuum-assisted venous drainage confirms functional placement.

Which complication results from advancing a two-stage venous cannula too deeply into the IVC?

Answer: Inadequate SVC drainage with superior vena cava hypertension and facial edema

Excessive IVC advancement positions the atrial drainage holes below the tricuspid valve, blocking right atrial drainage and causing SVC hypertension, facial plethora, and cerebral edema.

For which clinical scenario is axillary artery cannulation most commonly selected?

Answer: Aortic dissection repair requiring antegrade cerebral perfusion when the aorta is unsafe

Axillary artery cannulation provides safe arterial inflow in aortic dissection and allows antegrade cerebral perfusion via the innominate artery during circulatory arrest.

What is the function of a purse-string suture at a cannulation site?

Answer: To create a hemostatic seal around the cannula insertion site that prevents bleeding

Purse-string sutures placed concentrically around the cannulation site are cinched with a tourniquet to form a blood-tight seal around the cannula during bypass.