Capnography is an essential element when anaesthetising patients to help you achieve a positive outcomes for your patients and especially those more dangerous neonatal or small ones. This was highlighted in a recent article in the Veterinary Times (Vol 46 No5) by Carrington-Brown and Walsh.
The article states “Capnography can be used to aid the monitoring of ventilation and cardiac output”, both of which are critical parameters.
It continues, “There may be some inaccuracy because of the small tidal volume of neonatal patients when side- stream monitoring is used”.
We absolutely agree; when your patient has a small tidal volume, you have to question the value of removing a constant sample of 125ml/minute for a monitor that probably won’t give you accurate data.
Then comes the contentious bit: “mainstream monitors will be more accurate but the size of the sampling unit may increase dead space and produce physical drag”.This is where we disagree.
The older human capnographs (2nd hand) and the cheaper Chinese units sold as “veterinary monitors” certainly do suffer from this problem, but the VM-2500-M mainstream capnograph from Thames Medical has a neonatal dead space of just 0.6ml. With such low resistance, even the author (90kg with a tidal volume of 620ml) can breathe through it without too much discomfort.
To ease the minds of the nursing and veterinary staff that I work with, I ask them to breathe through the airway adapter themselves and I haven’t lost one yet!
The logic is simple; we want to monitor our smaller patients because they are the risky ones, they are the ones that can have problems and so we need to buy a Capnograph. So lets buy the cheapest we can find….NO……spend the extra £500, buy the piece of kit that will actually work properly on these very small patients that you need to be really careful with, from the people who actually know their subject and can support both your equipment and your staff. Buy a VM-2500-M mainstream Capnograph from Thames Medical.
The VM-2500-M is not the cheapest but the best and probably the only piece of kit that can actually accurately monitor the small risky patients.
Ask yourself which would you want for your own pet’s anaesthetic? The cheaper one, that might, if you are lucky, get some (all-be-it inaccurate) data? or the top-of-the-range unit that will capture accurate data for all sizes and species?