Homemade Infusion Pump Method for Injecting 5% Anestofol
I've been experimenting with a 35 ml syringe to which I have attached some elastic material (waistband elastic, 1 inch wide) which automatically pushes the syringe plunger down. With this setup, I believe I may be able to inject 30 ml of 5% Anestofol over a period of about 2 minutes (I have timed it, and it takes nearly 2 minutes to pass 30 ml).
Consciousness will be lost after around 15 seconds, but the waistband elastic will continue to inject the Anestofol. So this setup acts as a very cheap and simple infusion pump.
I connect the syringe to an infusion set about which has a 23 gauge needle (inner diameter 0.3 mm). The tube on this infusion set is about 30 cm in length (I use a TERUMO SURFLO winged infusion set).
Because the 23 gauge needle is narrow, it restricts the flow of the Anestofol. In my tests using 30 ml of water in the syringe, the waistband elastic pushed the water through the infusion set and needle at the following rates:
- 1st 10 ml of water took 26 seconds to pass, so flow rate is 10 / 26 = 0.38 ml per second.
- 2nd 10 ml of water took 33 seconds to pass, so flow rate is 10 / 33 = 0.3 ml per second.
- 3rd 10 ml of water took 46 seconds to pass, so flow rate is 10 / 46 = 0.22 ml per second.
Total time = 105 seconds = 1.75 minutes.
When the needle is inserted into a vein, the flow rate will be a little slower, as it will be working against blood pressure. But blood pressure will be quite low if you are lying down horizontally (venous blood pressure when lying horizontally is about 7 mmHg = around 10 cm of water).
In a second test with needle placed under the pressure of a 45 cm height of water, so as to simulate venous blood pressure, the following flow rates were achieved:
- 1st 10 ml of water took 33 seconds to pass, so flow rate is 10 / 33 = 0.3 ml per second.
- 2nd 10 ml of water — error in experiment, no data.
- 3rd 10 ml of water took 130 seconds to pass, so flow rate is 10 / 130 = 0.077 ml per second.
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I am just wondering if
upper airway obstruction when under the anaesthetic propofol might be an issue. Or will you have already lost consciousness before this happens?
According to AI:
Propofol results in a loss of pharyngeal muscle tone.
Propofol strongly suppresses:
- Genioglossus (the genioglossus is the primary muscle preventing tongue fallback)
- Pharyngeal dilator muscles
- Soft palate tension
When these relax:
- The tongue falls backward toward the posterior pharyngeal wall.
- The oropharynx narrows or closes.
- The soft palate may block the nasopharynx.