Test 1 content-Pathophysiology of CPB Flashcards
Blood flow to major organs is represented in three ways:
- As a percentage of total flow
- As volume per 100 grams of tissue per min
- As an absolute rate of flow in L/min
As metabolic requirements _____ sympathetic tone is ______ resulting in increased cardiac output and oxygen delivery
Increased, Increased
Circulatory control during CPB is determined by your _______
Pump flow
What 4 things determine pump flow capability?
- Equipment
- Venous return
- Arterial line pressure limits
- Arterial blood pressure
Cardiac output is determined by what 4 things?
- Pump flow
- Venous return
- Arterial blood pressure
- Arterial line pressure
Goal cardiac output =
Patient’s BSA x Cardiac index
Goal is 2.4 on CPB
BP of the patient on CPB influenced by 4 things:
- ANS
- Changes in venous drainage
- Administration of drugs (Vasodilator or vasopressor)
- Largely influenced by the perfusionist
Systematic blood flow is guided by 4 things during CPB:
- Patient specifics (age, comorbidities)
- Temp
- Depth of anesthesia
- Hematocrit
Max flow rate is determined by 4 things:
- Venous return
- Venous and arterial tubing diameter
- Size of cannulas (venous to allow for adequate drainage, arterial to allow for low enough line pressures)
- Presence of shunts
Arterial BP is the product of (2)
Cardiac output and SVR (systemic vascular resistance)
SVR is influenced by (6)
- Blood viscosity (Hematocrit and temp)
- Smooth muscle tone in the arterioles
- Depth of anesthesia
- Sympathetic nervous activity
- Acid base status
- Inflammatory mediators
Goal for arterial BP in CPB is ______
60 mmHg
T/F-Higher perfusion pressures may improve tissue perfusion in higher risk patients?
True
Patients that are older, hypertensive or have peripheral vascular disease are examples
Venous pressure is determined by (2):
- Blood volume
- Venous vascular tone (sympathetic nervous system, depth of anesthesia, vasoactive drugs, resistance from venous cannula, gravity drainage vs. vacuum assisted venous return)
As pump flow decreases there is progressively _____ organ perfusion
Less
splanchnic, renal and cerebral
At the ____1____ of CPB there is a ___2__ in systemic vascular resistance due to viscosity changes and hemodilution
- Onset
2. Decrease
There is _____ SVR during hypothermic CPB
Increased
During the rewarming phase of CPB patient response varies due to: (3)
- Anesthesia depth
- Underlying disease
- Hematocrit
There are _________ SVR changes as the cross clamp is removed and the heart is re-perfused
More consistant
Impaired tissue perfusion and oxygen delivery can lead to: (3)
- Post operative organ dysfunction both temporarily and sometimes permanent
- Variable decreases in oxygen consumption as compared to pre CPB values
- Increases in serum lactate levels
Microcirculation function can be impaired by: (4)
- Constriction of pre-capillary arteriolar sphincters
- Edema
- Loss of pulsatile flow
- Sludging in the capillaries in hypothermia
(sludging of blood intravascular agglutination of erythrocytes into irregular masses, interfering with circulation of blood.)
The loss of _________ once on CPB is one of the biggest physiological changes
Pulsatile perfusion
Roller pumps can mimic _______
Pulsatile perfusion
What are the perfusion goals of CPB (5):
- Maintain adequate oxygen delivery to all organs (important to watch cerebral head sats, venous sats, and arterial sats)
- Maintain adequate hematocrit and blood gas values within normal ranges
- Maintain goal BP
- Maintain adequate blood flow (cardiac output)
- Minimize stress response, inflammation, micro embolism and disturbances in the coagulation system
