Cardiac Surgery Flashcards
What does hypothermia during CPB do?
Decrease cerebral metabolic rate
Alkaline drift decreasing the PaCO2.
What is alpha stat management?
It allows the natural alkaline drift without correction
What is ph stat management?
It corrects the alkaline drift by adding CO2 to the oxygenation or sweeping the CO2 out.
What are the advantages of ph stat management?
- Improved oxygen delivery to tissues by counteracting the leftward shift of the oxygen dissociation curve due ton alkalosis
- Increased speed of homogenous cerebral cooling thru vasodilation
- Decreased CMRO2
- Increased CBF
During bypass, what is the most likely cause of activated clotting time variability?
Hemo dilution
What is activated clotting time?
Test of heparin’s effect
How is ACT tested?
Whole blood is added to a test tube with activator in it, diatomaceous earth or kaolin which stimulates the intrinsic coagulation pathway.
When clot forms it slows the descent of a plunger and increases the number generated the longer it takes the clot to form.
What factors can alter the ACT?
Hypothermia
Hemo dilution
TCP - Platelets < 30-50
Drugs affecting platelets (Asa, Plavix, prostacyclin)
Why are pediatric patients more likely to have variability with ACT?
Because they have increased consumption of heparin
What determines heart rate after transplant?
The donor atrium
What is the initial response to hypovolemia in a transplanted heart?
An increase in stroke volume dependent on adequate preload
What drugs have no action on the transplanted heart?
Anticholinergics
Why do you sometimes see 2 P waves on the EKG of a transplanted heart
Because the recipient atrium is still present and remains innervated, but signal don’t cross the suture line
What does a transplanted heart respond to?
Direct acting agents : isoproterenol, Epi, norepinephrine, dopamine, dobutamine
What is the fastest way to cool someone?
Endovasculqr cooling
When is then highest risk to patients when cooled?
During the rewarming process due to rapid rewarming. Must be done over 24 hours.
Can cause electrolyte shifts, increased ICP and arrhythmias
What is one of the complications of PAC use involving non-heparin coated catheters?
Endocarditis
What is the most common complication of PAC placement?
Arrhythmia
What are the complications associated with PAC use?
Pulmonary infarction PA rupture Thromboembolism Endocardium damage Tricuspid valve injury Pseudo aneurysm
What factors increase the risk of PA rupture?
Anti coagulation
Old age
Hypothermia
Pulmonary hypertension
Why do we use a double lumen tube when repairing a PA?
To prevent the other lung from contamination
Which anastomosis is done last in a CABG?
LAD
