Cardiothoracics Flashcards
Advantages of off pump vs on pump
Reduced fibrinolysis
Reduced risk of air emboli
Reduced neurological dysfunction
Reduced SIRS
Reduced fluid overload/depletion
Reduced risk of bleeding
Reduced M+M
Reduced renal dysfunction
Reduced platelet dysfunction
Reduced blood transfusion
Reduced consumption of clotting factors
Reduced hypothermia
Earlier extubation
Shorter/no ICU stay
What are the principles of cardioplegia during cardiac surgery? (4)
Arrests the heart in diastole
Minimises metabolic activity
Facilitates surgery with a bloodless field
Protects cardiac cells by cooling the heart
What is the formula for coronary perfusion pressure (CPP)?
CPP = Aortic pressure (P1) - Arterial capillary pressure (P2)
Name the complications associated with post-cardiac surgery
Bleeding
Cardiac tamponade
Arrhythmias
Electrolyte imbalances
Infection
What are the common steps in weaning from cardiopulmonary bypass?
Rewarm
Remove cross-clamp
Restart pulmonary ventilation with high FiO₂
Monitor heart rhythm and stabilise with pacing if needed
Wean down flow until off bypass
Clamp + remove venous line
Reverse heparin with protamine
Return volume as needed and then remove arterial line after protamine
What are the types of cardiac assist devices?
Intra-aortic balloon pump (IABP)
Ventricular assist devices (VADs)
Extracorporeal membrane oxygenation (ECMO)
What are the anaesthetic challenges of thoracic surgery?
Managing one-lung ventilation.
Preventing hypoxia.
Minimising cardiovascular instability during lung resection.
Handling complications such as pneumothorax or arrhythmias.
What is the role of functional respiratory tests in preoperative assessment?
They evaluate pulmonary reserve and predict the risk of postoperative complications
Tests include FEV1, DLCO, CPEX
Name the complications of one-lung ventilation
Hypoxia
High airway pressures
Bronchial tube malposition
Shunting of blood
What are the methods of airway management for one-lung ventilation?
Double-lumen endotracheal tube (DLT).
Bronchial blockers.
What are the common causes of aortic stenosis?
Calcification (common in the elderly)
Bicuspid aortic valve (younger patients)
Rheumatic fever
What are the key haemodynamic goals during surgery for severe aortic stenosis?
Maintain preload
Preserve sinus rhythm
Avoid tachycardia
Maintain afterload
What are the clinical features of mitral regurgitation?
A:
Breathlessness
Fatigue
Chest pain
Dizziness
What is the role/indications of a pulmonary artery catheter (PAC)?
Measures cardiac output via thermodilution
Guide fluid therapy in theatre + ICU
Guide inotrope + vasopressor requirements
Monitors right heart and pulmonary artery pressures (PAC only)
Differentiates cardiogenic from non-cardiogenic pulmonary oedema (PAC only)
What are the advantages of transoesophageal echocardiography (TOE)?
Provides real-time assessment of cardiac filling, output, and valvular function
What are the indications for intraoperative cardiac output monitoring?
Guiding fluid therapy in theatre or ICU
Guiding inotrope + vasopressor requirements
Assessing right heart pressures (PAC)
Differentiates cardiogenic from non-cardiogenic pulmonary oedema (PAC)
What is cardiac tamponade?
Cardiac tamponade is the compression of the heart due to pericardial effusion
Signs of cardiac tamponade?
Beck’s triad -
- Hypotension
- Muffled heart sounds
- Raised JVP
Tachycardia
Dyspnoea / SOB
Increasing vasopressor requirement
Pericardial rub (soft sign, may be present as a result of surgery)
Sharp chest pain (unreliable)
Pulsus paradoxus - abnormally large reduction in systolic pressure during inspiration
Spontaneous inspiration → full right heart encroaches on left → blood pools in the pulmonary vasculature → reduced left heart filling → decrease in systolic pressure
In tamponade: effect is exacerbated, difference in pressure between R + L heart is lost
Kussmaul’s sign - rise/lack of fall of JVP with inspiration (constricted right heart fails to accommodate increase in venous return that occurs with drop in intrathoracic pressure)
How is acute hypoxia managed during one-lung ventilation?
Administer 100% FiO₂
Reassess tube placement and suction secretions
Apply CPAP to the non-ventilated lung if needed
Consider intermittent two-lung ventilation
Name common causes of high airway pressures during thoracic surgery
Bronchospasm
Pneumothorax
DLT malposition
Acute lung injury
What are the goals in managing pulmonary hypertension perioperatively?
Avoid hypoxia and hypercarbia.
Maintain normothermia.
Use pulmonary vasodilators like nitric oxide.
Composition of cardioplegia solution + physiological effects (4+4)
High potassium (84mmol, when mixed with body ends up 20mmol) - arrests heart in diastole
Low calcium - reduces amount available for contraction
High magnesium - competes with calcium
Low/normal sodium - can induce arrest
Bicarbonate/histidine/buffer - offset metabolic acidosis tendency
Mannitol - raise osmolarity of solution to reduce tissue oedema
Blood - oxygen-carrying capacity
Routes of administration of cardioplegia solution (2)
