The practice of reducing the core temperature of a cardiac arrest or stroke patient to protect the brain and increase the probability of a full return to normal function is rapidly gaining acceptance and practice in the EMS arena.
Evidence from multiple clinical studies show positive results from the use of therapeutic hypothermia (TH).(1–5) EMS systems are developing protocols and practices for its use in the field. The process of TH involves deliberately cooling down a patient’s body to between 32–34˚C to reduce hypoperfusion and reperfusion injury, especially to the brain.
To achieve this cooling state, prehospital systems use methods such as surface cooling with cold blanket technology and ice packs, vascular infusion of chilled saline, or a combination of these.
But what if infusion of chilled saline through intravenous access isn’t possible due to collapsed veins? Can the go-to tool in the EMS technician’s kit—intraosseous (IO) access with a device like the EZ-IO Intraosseous Infusion System—be used?
IO to Reduce Core Body Temperature
A number of case reports and studies demonstrate the effective use of IO vascular access in reducing core body temperature.(6–8) In the most recently published abstract, researchers described a study designed to determine whether IO access could be used as effectively as IV access to reduce core temperatures.(9)
The answer is “yes.” And as TH adoption continues, chilled infusion through the IO route with devices like Vidacare’s EZ-IO Intraosseous Infusion System, particularly in the humeral insertion site, should be considered.
Presented at the National Association of EMS Physicians conference in January, the abstract “Infusing Chilled Saline through the Intraosseous Route Is Equivalent to Infusion through the Intravenous Route in Reducing the Core Temperature in Swine” concluded that IO and IV access are equally efficient in administering a chilled saline solution to reduce core body temperature.
Authored by Larry Miller and his Vidacare research team, the study compared effectiveness in reducing core body temperature using both IV and IO access in eight swine, recording data using brain, esophageal and rectal temperature probes.
The study concluded that IO and IV temperature reductions were statistically equivalent. 9
Humeral Site for Optimal Flow
When using IO access to induce TH on a patient, the optimal site may be the proximal humerus. Two recent studies demonstrated flow rates are greater in the humerus than the tibia and have high prehospital placement success rates.(10–11)
In one article, “Hurt So Good; Easing IO pain and pressure,” researchers studied the relationship between infusion pressure and flow rates; and the effect of lidocaine on intraosseous infusion pain for the tibia and humerus insertion sites.(10)
The study’s authors concluded that the proximal humerus should be strongly considered for optimal flow rates as data showed the humerus provides greater flow rates than the tibia at all infusion pressure levels.
While the tibia provides adequate IO infusion rates for most situations, when greater flow rates are required, the proximal humerus proved superior. Moreover, IO infusion pain is more easily managed through the humeral site for the conscious patient.
A second study on the humeral insertion site, “Humeral Intraosseous Access Success Rate in Adult out-of-Hospital Cardiac Arrest,” explores success with the proximal humerus in the prehospital cardiac arrest patient. In a report of results, researchers examined 405 cardiac arrests, with humeral access attempts in 61% of the cases.(11)
The overall success rate was 94%, and first attempt successful placement —defined as stable placement with sufficient flow—was 91%. This study illustrated a high degree of paramedic success in establishing IO access outside the hospital and showed humeral IO access to be a reliable method of fluid and medication delivery for the out-of-hospital cardiac arrest population.
Contraindications for use of the EZ-IO device are fractures, excessive tissue or the absence of anatomical landmarks, infection at the area of insertion, significant previous orthopedic procedure at the site (i.e., IO in the past 48 hours or a prosthetic limb or joint).
As the practice of TH increases, the ability to obtain rapid and reliable vascular access for cooling is vital. Devices like the EZ-IO Intraosseous Infusion System make that possible.
To ensure success and optimal flow follow standard IO guidelines: consider the proximal humeral site, flush first, use a pressure bag or infusion pump, and remember that any fluid or drug that can be infused through a peripheral IV can be infused through IO.(12–13)
Vidacare’s EZ-IO Intraosseous Infusion System—the first battery-powered device to establish immediate vascular access and the first IO device cleared by the Food and Drug Administration for humeral insertion—is currently used by 90% of the ALS ambulances in the U.S. and more than 50% of U.S. emergency departments, as well as throughout the U.S. military.
1. Bernard SA, Gray TW, Buist MD, et al. Treatment of comatose survivors of out-of-hospital cardiac arrest with induced hypothermia. N Engl J Med. 2002;346(8):557–563.
2. Hypothermia after Cardiac Arrest Study Group. Mild therapeutic hypothermia to improve outcome after cardiac arrest. N Engl J Med. 2002;346(8):549–556.
3. 2005 AHA Guidelines for CPR and ECC. Circulation. 2005;112 [SI]:IV-84–IV-88.
4. Hoedemaekers CW, Ezzahti M, Gerritsen A, et al. Comparison of different cooling methods to induce and maintain normo- and hypothermia in ICU patients: A prospective intervention study. Crit Care Med. 2007;11(4):R91.
5. Cabanas JG, Brice JH, De Maio VJ, et al. Field-induced therapeutic hypothermia for neuroprotection after out-of-hospital cardiac arrest. J Emerg Med. 2011;40(4):400–409.
6. Myers BJ & Lewis R. Induced cooling by EMS (ICE): Year one in Raleigh/Wake County. JEMS. 2007;32(Supp):13–15.
7. Mader TJ, Walterscheid JK, Kellogg AR, et al. The feasibility of inducing mild therapeutic hypothermia after cardiac resuscitation using iced saline infusion via an intraosseous needle. Resuscitation. 2010;81(1):82–86.
8. Truhlar A, Skulec R , Rozsival P, et al. Efficient prehospital induction of therapeutic hypothermia via intraosseous infusion. Resuscitation. 2010;81(2)262–263.
9. Miller L J, Montez DF , Puga TA et al : Infusing chilled saline through the intraosseous route is equivalent to infusion through the intravenous route for reducing core temperature in swine [abstract]. Prehosp Emerg Care. 2012;16(1):152–187.*
10. Philbeck TE, Miller L J, Montez D, Puga T: Hurt so Good: Easing IO pain and pressure. JEMS. 2010;35(9):58–69.*
11. Wampler D , Schwartz D , Shumaker J. Paramedics successfully perform humeral EZ-IO intraosseous access in adult out-of-hospital cardiac arrest patients. Am J Emerg Med. (2011) doi:10.1016/j.ajem.2011.07.0101.
12. Von Hoff DD , Kuhn JG, Burris HA, Miller LJ: Does intraosseous equal intravenous? A pharmacokinetic study. Am J Emerg Med. 2008;26:31–38.
13. Hoskins SL, et al. Pharmacokinetics of intraosseous and central venous drug delivery during cardiopulmonary resuscitation. Resuscitation. (2011), doi:10.1016/j.resuscitation.2011.07.041.
* Research sponsored by Vidacare Corporation