All our cardiac arrest patients roll in these days with an IO in place – and we are full proponents of rapid, successful access in the uncontrolled field environment. But, how effective is it really in the CPR situation?
So, this is an animal study that tries to address the theoretical efficacy of intraosseous access versus central venous access. They use injection of dye tracers into Yorkshire swine for a comparison between intraosseous sternal, intraosseous tibial, and external jugular central venous cannulation.
Unfortunately, this is a good news/bad news study. The good news – peak concentrations were achieved only slightly more slowly in the arterial circulation following sternal intraosseus injection than the gold standard central venous injection. And, the peak concentrations were nearly identical. Bad news, the tibial IO was half the speed and half the arterial peak concentration of the sternal IO.
In theory, this is of relative importance depending on which medication you’re using – presumably the speed of administration matters in CPR and peak concentration may matter as well. Of course, this is limited as 1) pigs and 2) efficacy vs. effectiveness, because they’re not measuring clinical outcomes.
But it’s interesting to worry about. Too bad it’s hard to do chest compressions with your access point where your hands are supposed to go. It would be interesting to compare this result to a humeral head IO.
“Pharmacokinetics of Intraosseous and Central Venous Drug Delivery During Cardiopulmonary Resuscitation.”
http://www.ncbi.nlm.nih.gov/pubmed/21871857
(My not so humble views as a field provider comfortable with IO access)
I've not done CPR with a sternal IO in place, but it's my understanding they're placed in the manubrium, which theoretically should limit the interaction between the compressor and the IO access. That being said, I agree with you and I'm not sure how I feel about rhythmically flexing any IV/IO access. I'd be worried about backing it out. I also don't want to have to stop CPR to place my IO.
Humeral access during CPR is a bit of a "busy" location to use too, both pre-hospital and in-hospital. You need to be along side the patient and properly position the arm across the abdomen to expose the humeral head (this maximizes success with the obese EZ-IO needle). You've also got somebody's knees (in the field) up near the patient's shoulders while they're ventilating. If we had infinite room and I wasn't staging rescuers on both sides of the chest to ensure adequate compressors are available, I'd consider it during a code. Otherwise, it's not a bad access point and I've heard it is preferred in conscious patients.
On a code in the field, hands down the simplest location is the proximal tibia. It is not only easily identified in nearly every patient, it has predictable success rates and reliability. Usually, it is easy to get to and does not require rescuers to be crowded. CPR continues unabated while access is obtained. My only complaint is you no longer have a convenient place to put the monitor and O2 during patient movement!
I think the pharmacokinetics of the locations are interesting, but given the relative paucity of good studies on drugs during codes it isn't necessarily helpful in deciding where to place your access. The Jacobs et al study in Resus (2011 Sep;82(9):1138-43) certainly reinforces the need for more RCT's on code meds.
Interesting study nonetheless, and I look forward to fluoroscopic videos from the authors!
(My not so humble views as a field provider comfortable with IO access)
I've not done CPR with a sternal IO in place, but it's my understanding they're placed in the manubrium, which theoretically should limit the interaction between the compressor and the IO access. That being said, I agree with you and I'm not sure how I feel about rhythmically flexing any IV/IO access. I'd be worried about backing it out. I also don't want to have to stop CPR to place my IO.
Humeral access during CPR is a bit of a "busy" location to use too, both pre-hospital and in-hospital. You need to be along side the patient and properly position the arm across the abdomen to expose the humeral head (this maximizes success with the obese EZ-IO needle). You've also got somebody's knees (in the field) up near the patient's shoulders while they're ventilating. If we had infinite room and I wasn't staging rescuers on both sides of the chest to ensure adequate compressors are available, I'd consider it during a code. Otherwise, it's not a bad access point and I've heard it is preferred in conscious patients.
On a code in the field, hands down the simplest location is the proximal tibia. It is not only easily identified in nearly every patient, it has predictable success rates and reliability. Usually, it is easy to get to and does not require rescuers to be crowded. CPR continues unabated while access is obtained. My only complaint is you no longer have a convenient place to put the monitor and O2 during patient movement!
I think the pharmacokinetics of the locations are interesting, but given the relative paucity of good studies on drugs during codes it isn't necessarily helpful in deciding where to place your access. The Jacobs et al study in Resus (2011 Sep;82(9):1138-43) certainly reinforces the need for more RCT's on code meds.
Interesting study nonetheless, and I look forward to fluoroscopic videos from the authors!
Tibia is definitely the simplest – and whether any efficacy study bears out a difference in outcomes when comparing proximal vs distal sites of access remains to be seen. This is particularly difficult in code situations when there's hardly any evidence that anything works – but, in theory, epinephrine does have short-term ROSC endpoints, so maybe they could run a similar small cohort study in pigs as well.
I still want someone to re-do the nitroprusside pigs study without all the confounding variables and fewer arms to verify those findings and determine if human trials are warranted.
Tibia is definitely the simplest – and whether any efficacy study bears out a difference in outcomes when comparing proximal vs distal sites of access remains to be seen. This is particularly difficult in code situations when there's hardly any evidence that anything works – but, in theory, epinephrine does have short-term ROSC endpoints, so maybe they could run a similar small cohort study in pigs as well.
I still want someone to re-do the nitroprusside pigs study without all the confounding variables and fewer arms to verify those findings and determine if human trials are warranted.