Effects of PPV Flashcards
What can decrease Coronary Blood Flow with PPV?
- Decreased CO or Decreased BP
- Increased Intrathoracic pressure
What does peep do to MAP
Peep adds to MAP 1 to 1
What other organs are effected by PPV
5 things
- ICP and Cerebral Perfusion
- GI bleeding,
- Ulcers
- Liver dysfunction
- Decreased Blood flow to kidneys
What are the 3 Renal Effects
1) Redistribution of renal flow
2) Increase in Anti-Diuretic Hormone (ADH)
3) Decreased secretion of Atrial Natriuretic Peptide (ANP)
What causes reduced overall blood flow in kidney?
Lowered BP
How is blood flow redistributed in kidney in the presence of PPV?
What Occurs when this happens?
- Flow to inner cortex is less
- More Na is reabsorbed (and with it comes water)
Increasing ADH equates to?
Fluid retention and Decreased Urinary Output
What causes an increase in ADH?
- Decreased Left Atrial volume
- Decreased Blood Pressure via the Carotid and Aortic baro receptors
What releases Atrial Natriuretic Peptide and what does it cause?
Atria distention which then causes diuresis
a PaO2 and CO2 of what can cause an effect of the kidney?
PaO2 < 40
CO2 > 65
What GI function is effected?
- Liver malfunction
- Gastric mucosal ischemia
- Critical patients may have gastric ulcers
- Treat with antacids or histimine H2 blockers
What are the types of Ventilator-Associated Lung Inuries?
5 things
- Barotrauma
- Volutrauma
- Atelectrauma
- Biotrauma
- Multiple-Organ Dysfunction Syndrome
What are the Predispositions of Barotrauma?
6 things
- High Pressures
- Blebs
- High PEEP
- Aspiration of Gastric Acid
- Necrotizing Pneumonia
- ALI/ADS
What are the effects of PPV on Gas Distribution and Pulmonary Blood Flow
6 things
- Ventilation to Nondependent Lung
- Ventilation to Lung Periphery
- Increase in Dead Space
- Redistribution of Pulmonary Blood Flow
- High levels can increase PVR
What are hazards of Oxygen Therapy with Mechanical Ventilation?
3 things
- Oxygen Toxicity
- Absorption Atelectasis
- Depression of Ventilation
What a happens to the atria during PPV?
Reduced atrial stretch during PPV
This causes less ANP to be released = less diuresis
Describe the Throacic Pump Mechanism between PPV and Spont breathing
during spont breathing, the lungs go more negative and increases venous return
During PPV, the lungs go positive and venous return decreases
What is an adverse effect of PPV to the pulmonary vascular resistance?
excessive stretch of lungs can stretch the capillaries and increase the PVR
Increased PVR can cause stretch of Right heart leading to ventricular septal deviation and shrinking of left ventricle, IF THE RIGHT HEART CANT OVERCOME IT.
What can PPV do in the presence of Left heart failure causing pulmonary edema?
PPV can decrease venous return
Decreases in CO can over time decrease preload in left ventricle.
Resting the left heart
What during PPv can affect Coronary Blood flow?
Decreased CO or Decreased BP
therefore decreased pressure gradient for coronary flow - You need good diastolic pressure for it.
increased Intra thoracic pressure - This compresses the heart
How can you minimize the effects of PPV?
- Shorter I-times
- Lower Pips
- Keep an Eye in MAP and the amount of Peep you use
What is the equation for Mean Airway Pressure (PAW)?
MAP = [0.5(PIP-PEEP) x (I Time/ TCT)] + PEEP
What can PPV do to gastrointestinal system?
Positive pressure-induced splanchnic hypoperfusion causing gastric bleeding leading to ulcers
Liver dysfunction due to pressure from diaphragm above (Liver cell damage)
What do decreases in CO and SV cause within the body?
increases in sympathetic response (vasoconstriction)
This results in increase in HR to compensate
Many pts have this prior to vent – then as we correct hypoxemia, acidosis, it decreases and hypotension can result
What is biotrauma?
What does this lead to?
It is a release of inflammatory mediators that cause a systemic inflammatory response to non pulmonary organs.
Leads to Multiple-Organ Dysfunction Syndrome
This is caused by Volutrauma, Barotrauma, or Atelectrauma in the lungs.
