A new study shows a decreased survival in out of hospital cardiac arrest(OHCA) when intraosseous(I/O) access is used instead if intravenous(IV) access as a means of delivering fluids and medications.

I/O lines provide rapid access where IV is not available and are progressively being used as the first line of access, primarily because they are quick, easy, don’t interfere with resuscitation efforts and can have anything given through them. Will this study change my practice? Will it change yours? Let’s look at what they found?

What did this study show

In this study 13155 patient were assessed for various outcomes including good neurological outcome at discharge. The results were:

  • 1.5% of those receiving I/O access had a discharge with favourable neurological outcome compared to
  • 7.6% where IV access was used.

Details of the Study

  • It is retrospective
  • It is a secondary analysis of the Resuscitation Outcomes Consortium Prehospital Resuscitation Using an Impedance Valve and Early Versus Delayed (PRIMED) study which included adult patients with non-traumatic out-of-hospital cardiac arrests(OHCA) treated during 2007 to 2009.
  • It looked at I/O access being the primary route of access attempted and therefore excluded patients with
    • no access
    • both I/O and IV
  • A total of 13155 patients were included in the study:
    • 660 patients had I/O access
    • 12495 patients had IV access

There are limitations in this study that are well set out and include:

  • It is a retrospective study
  • There is a comparatively small number of patients in the cohort that had I/O access
  • There may certainly be bias here due to the study’s retrospective nature ie., those patients with I/O access may simply be the sicker patients and thus would have a worst outcome.

Previous studies have also shown this. A retrospective cohort study in Resuscitation in 2017 looked at vascular access in OHCA and compared I/O vs IV access in 1800 patients. There were three endpoints measured:

  1. Survival to hospital admission
  2. Return of spontaneous circulation
  3. Survival to hospital discharge

I/O access performed less favourably for all endpoints

  • SURVIVAL TO HOSPITAL ADMISSION 38.5%(I/O) vs 50.0%(IV) p < 0.001
  • ROSC 43.6%(I/O) vs 55.5%(IV), p < 0.001
  • SURVIVAL TO HOSPITAL DISCHARGE 14.9%(I/O) vs 22.8%(IV), p = 0.003

One other question needs to be asked:

“Is what we are giving being delivered in the same way by I/O and IV routes?”

  • We know that bone marrow flow decreases significantly with decreased output in cardiac arrest.
  • We also know that adrenaline can result in a decrease in bone marrow flow and an increase in bone marrow vascular resistance.
  • We also know that when the concentration of drug delivery to the atrium is measured, drugs given by I/O line are significantly decreased in concentration(53%)

What does it all mean?

At this point we have some indication that there are less favourable outcomes with I/O versus IV lines. The studies are retrospective and have limitations. I will continue to use I/O and gain IV access or central access as soon as possible. It is worth considering the use of higher doses of medications when given via the I/O route. Should we give twice the dose, ten times the dose? No-one really knows. In one study in Circulation, ten times the dose of adrenaline was given via the I/O line.

We need a prospective  randomised trial on this. More to come.

References

  1. Kawano T, Grunau B et al. Intraosseous Vascular Access is aAssociated With a Lower Survival and Neurologic Recovery Among Patients With Out of Hospital Cardiac Arrest. Annals of Emergency Medicine. May 2018. Vol 71, Issue 5, pp 588-596
  2. Feinstein BA, Stubbs BA, Rea T, et al. Intraosseous compared to intravenous drug resuscitation in out-of-hospital cardiac arrest. Resuscitation. 2017;117:91-96
  3. DelguercioLR, CoomaraswamyRP, State D. Cardiac output and other hemodynamic variables during external cardiac massage in man. NEJM. 1963;269:1398-1404
  4. VoelckelWG, Lurie KG, McKniteS, et al. Comparison of epinephrine with vasopressin on bone marrow blood flow in an animal model of hypovolemic shock and subsequent cardiac arrest. CritCare Med. 2001;29:1587-1592
  5. Hoskins SL, do Nascimento P Jr, Lima RM, et al. Pharmacokinetics of intraosseous and central venous drug delivery during cardiopulmonary resuscitation. Resuscitation. 2012;83:107-112
  6. Harris J, Coute R et al. Coronary Perfusion Pressure Response to Administration of Interosseous Epinephrine After Prolonged Cardiac Arrest. Circulation. 2012;126:A252