Answering your questions By MLO

Edited By Brad S. Karon, MD, PhD

Drawing from intraosseous vascular access

Q
Our ER at times places intraosseous- (IO-) vascular access devices on patients who are in cardiac arrest or critically ill. ER staff are drawing blood from this access before they use it for fluid and drug administration. What testing can actually be performed on this blood sample? ER staff orders a complete blood count with differential. These samples definitely have bone marrow in them, as we see high white blood counts and precursor white blood cells in the differential. Should the patient only have the hemoglobin reported? The same goes for chemistry tests. The ER routinely orders a basic chemistry panel that includes sodium, potassium, chloride, BUN, creatinine, glucose, and calcium. To me, this is bone marrow; and we do not have normals for bone marrow — and, as a result, do not want tests reported with normals for peripheral bloods. I have only one article that states that you could perform sodium, potassium, magnesium, calcium, glucose, lactose, and hemoglobin and blood type. Do you know of other data to support this?

AIntraosseous-vascular access is the use of the bone-marrow cavity for infusion of fluids or medication. This route has been used since the 1920s but has fallen out of favor with the use of plastic catheters allowing better access to peripheral or central veins. More recently, IO access has been gaining popularity for rapid resuscitation, especially in children and for military-trauma patients. Its main advantages are speed and high success rates in gaining vascular access in emergency situations. For instance, with proper training and equipment, IO access can be achieved in 30 to 60 seconds with better than 80% success. Mean times for other routes were three minutes for peripheral veins, eight minutes for central vein catheter, and 12 minutes for a cutdown. Remember that this is used in critically ill patients who may be in shock or cardiac arrest.^1,2

Typically, a large-bore special needle is inserted into the proximal tibia, distal femur, or iliac spine of the pelvis or sternum. It is usually left in place for about 24 hours. The complication rate is comparable to the use of other vascular access methods. Generally, any fluid or medication that can be given intravenously can be infused by IO.

The bone-marrow cavity contains a rich vascular supply. Aspiration from the cavity yields a sample that contains blood, bone-marrow cells, and fat. Several papers have studied whether IO obtained samples can be used for laboratory analysis.^3,4,5,6 Each of the studies examined IO specimens compared with specimens from venipunctures. One study was performed on healthy dogs, while the others were done on children receiving bone-marrow exams and who were not in shock or cardiac arrest. Not all of the studies were in agreement about the usefulness of IO specimens for some analyses, nor did all of the studies compare the same tests.

Valid results were reported for the following analytes: sodium, chloride CO² or bicarbonate. pH, urea, creatinine, albumin, calcium, phosphate, uric acid, total bilirubin, hemoglobin.

Studies were in agreement that the following analytes did not yield valid results: pO₂, ionized calcium, white blood cell count, platelet count.

There was disagreement about the following analytes: potassium, pCO₂, hematocrit, aspartate aminotransferase (AST), alanine aminotransferase (ALT).

Some analytes did not compare well between the IO and venous samples but were considered to be probably clinically useful anyway: glucose, hematocrit, total protein.

These studies were performed on animals and children who were hemodynamically stable. There is one study that examined IO and central-venous sampling in animals during cardiac arrest and resuscitation — a scenario much more likely to occur.⁷ During the first five minutes after cardiac arrest and resuscitation, values for sodium, potassium, magnesium, lactate, glucose, and hemoglobin for IO and central-venous samples are similar if they are obtained before fluids or drugs are given through the IO site. After this time, however, test values are likely to be different because of low blood flow in the marrow and contamination with infused fluids or drugs.

– From the library of
Daniel M. Baer, MD (deceased)
MLO Tips editor 1984 to 2009

References

1. Buck, ML. Intraosseous Administration of Drugs in Infants and Children. Pediatr Pharm. 2006;12(12).
2. Dubick MA; Holcomb JB. A review of intraosseous vascular access: current status and military application. Mil Med. 2000; 165(7):552-559.
3. Hurren JS. Can blood taken from intraosseous cannulations be used for blood analysis? Burns. 2000;26(8):727-730.
4. Ummenhofer W, Frei FJ, Urwyler A, Drewe. Are laboratory values in bone marrow aspirate predictable for venous blood in paediatric patients? Resuscitation. 1994;27(2):123-128.
5. Orlowski JP, Porembka DT, Gallagher JM, Van Lente F. The bone marrow as a source of laboratory studies. Ann Emerg Med. 1989;18(12):1348-1351.
6. Grisham J, Hastings C. Bone marrow aspirate as an accessible and reliable source for critical laboratory studies. Ann Emerg Med. 1991; 20(10):1121-1124.
7. Johnson L, Kissoon N, Fiallos M, Abdelmoneim T, Murphy S. Use of intraosseous blood to assess blood chemistries and hemoglobin during cardiopulmonary resuscitation with drug infusions. Crit Care Med 1999; 27:1147-1152..

Brad S. Karon, MD, PhD, is associate professor of laboratory medicine and pathology, and director of the Hospital Clinical Laboratories, point-of-care testing, and phlebotomy services at Mayo Clinic in Rochester, MN.

MLO’s “Tips from the Clinical Experts” provides practical, up-to-date solutions to readers’ technical and clinical issues from a panel of experts in various fields. Readers may send questions to Brad S. Karon, MD, PhD, by e-mail at [email protected].