The occasional intraosseous infusion.

Long bones in infants are filled with marrow that contains vascularized sinusoids. These sinusoids eventually drain into the systemic venous circulation. The marrow cavity acts as a rigid vein and so will not collapse, even in the face of severe volume loss. No matter how dehydrated or volume-depleted the child is, there is always a rigid tube that can be punctured to replace the required fluids. The marrow is very vascular in infants. At about age 5, this marrow is replaced by less vascular marrow, and, although the intraosseous (IO) route is still available in older children and adults, it is a more difficult route for rapid volume replacement, compared with venous access. It is, however, still a good route for giving medications if peripheral access is not possible, and advanced cardiac life support protocols now prefer IO access over the endotracheal route for drug administration. Although bolus medications are rapidly effective, it is necessary to do a saline flush after each drug, and to administer volume under pressure using syringe and stopcock, infusion pump or pressure bag. Maximum rate of administration is equivalent to a # 21 peripheral cannula.