What contributes to adverse events with the use of ketamine for PSA (Procedural Sedation and Analgesia) in children?
The pre-PSA use of fentanyl or morphine or concomitant use of midazolam and/or atropine was not associated with an increased in adverse event in either IM or IV ketamine (Table 1).
However, there was a trend toward different rates of adverse events with the use of some medications in addition to ketamine. A larger study would be able to tell if these trends are real or just normal statistical variation.
The use of morphine, fentanyl, and midazolam would be expected to cause some adverse effects, but midazolam seems to provide protection from adverse events.
Morphine and fentanyl were used so infrequently, that drawing any conclusions from such small numbers is a bad idea.
Why does midazolam appear to protect against adverse effects?
Even more interesting is the possible harm caused by atropine.
Why would atropine increase the rate of adverse events?
Why do we give atropine to children?
To prevent ourselves from being able to see the effects of hypoxia on the child’s heart rate.
We give children atropine to prevent their heart rates from dropping when we are doing things that are expected to occasionally result in hypoxia.
The child’s heart rate is a great indicator that we are making the child hypoxic, but we prefer to not know about the hypoxia.
Should we also avoid pulse oximetry?
We even delay our ability to identify hypoxia with pulse oximetry by using supplemental oxygen. That doesn’t mean that we should not use supplemental oxygen, only that we should assess ventilation with a measurement that is not affected by supplemental oxygen – waveform capnography.
Atropine should not be used to keep the pediatric heart rate from responding to hypoxia.
The way to prevent pediatric bradycardia is to prevent hypoxia, not to put lipstick on the hypoxia.
What hypoxia? No hypoxia here. Just a pulchritudinous paramedic.
Atropine is also used as an antisialog, which means that it decreases salivation. That can be an appropriate use, but if the atropine prevents the recognition of hypoxia, some saliva in the mouth may not be that important or we should use suction (just as the dentist does).
However, the study was not designed to look at that and the numbers never reached statistical significance. Does that mean that we should continue to use atropine for something that is not beneficial?
Where is the evidence that there is any benefit to anything other than the ego of the person pushing the atropine?
Oh, look! Better numbers on the monitor.
We should not be harming our patients with drugs.
To be continued in Part II, which looks at the actual IM vs. IV results.
Thank you to Peter Canning, of Street Watch: Notes of a Paramedic, for this journal article.
Melendez E, & Bachur R (2009). Serious adverse events during procedural sedation with ketamine. Pediatric emergency care, 25 (5), 325-8 PMID: 19404223