Lecture 19: Transvascular Diaphragm Pacing Flashcards
What patients are a candidate for temporary assisted ventilation?
critically ill patients in intensive care
patients undergoing surgery under general anesthesia
vs patients with SCI who need it permanently
Could VIDD be Prevented by Pacing the Phrenic Nerves in the ICU? What could be the benefits?
Induce diaphragmatic contractions to
1. maintain diaphragmatic endurance
2. provide exercise and strengthen an already weakened diaphragm
3. provide negative pressure ventilation, thereby replicating a more physiological respiratory pattern
eliminate VIDD and Ventilator-Induced Lung Injury
- improve clinical outcomes in ICU
- shorten hospital stay
- significantly reduce healthcare costs
- simple to place
- easy to use
- temporary and easily removable
- Protect the diaphragm
- Protect the lungs
- Assist the heart (venous return is assisted by pumping by the diaphragm)
- Reduce nosocomial infections,
pneumonia - Accelerate weaning
- Liberate patients from mechanical ventilation
- Reduce mortality rates
- Improve survivor’s quality of life
What % of patients can wean on and off ventilator?
70% manage to wean
30% don’t manage to wean and become dependent on ventilator
What idea did Dr. Hoffer have after coming back to Canada?
Minimally invasive nerve stimulation method and apparatus: intravenous catheter to pace nearby nerves
transvascular stimulation
put electrodes in catheter
provisional patent. full patent must include everything you submit in provisional patent
date at which you submit patent gives you priority over others who may also file a patent
left phrenic nerve tucks behind left subclavian just behind clavicle. left subclavian vein then feeds into superior vena cava
if electrodes are placed inside left subclavian vein, you can stimulate both left and right phrenic nerve
field intensity adjusted so you only stimulate selectively
bipolar stimulation for an even smaller field.
length of catheter is appropriate to reach both nerves but not further into the heart. electrode rotated slightly to account for place of left and right phrenic nerve
How can you tell where the phrenic nerve is?
During surgery,
advance a search electrode into the left subclavian vein and stop every cm and stimulate.
different minimum value threshold current. observe a twitch in the abdomen of the pig. observe a parabolic curve indicative of proximity to phrenic nerve.
watch the trace of the ventilator air flow to see when phrenic nerve activates diaphragm.
2 minutes to place, 30s to take it out
How does diaphragm pacing assist the ventilator when used simultaneously?
mechanical ventilators use positive pressure. this can cause lung injury
diaphragm pacing provides negative pressure to inflate lungs more normally, reducing peak ventilator pressure needed to inflate lungs
timed to pace/stimulate before next breath
Slide 15: what was the point of that?
you can time the onset of stimulation to start before, at the same time, or after the next ventilator breath
To prevent patents to claim that “we do it different” . claim you do it all
What is the role of the therapist in the use of the lung pacer?
decide how hard to stimulate diaphragm
has a dial, pick a value (10% effort, 25%, etc.)
can be closed loop as there are sensors to measure flow of air in response to diaphragm contraction.
don’t want full blast cause you can fatigue diaphragm and have too much negative pressure. overstimulation –> less and less force
describe how the lung pacer is a close loop
slide 17
disturbances: change posture of patient, can affect efficiency of breathing
catheter can jump a bit with heart beat and breathing, effecting pacing
Describe of
Diaphragm Pacing Therapeutic Protection System
slide 25
- catheter can also deliver fluid?
