Safety & Tolerability of Hypertonic Saline Administration Via Intraosseous Access

HTS is used to mitigate and temporize intracranial pressure (ICP) elevations and cerebral edema by creating an osmotic gradient across the cell wall. HTS is part of the elevated ICP algorithm in the emergency neurologic life support protocols HTS is superior to mannitol which is the alternate osmotherapy agent . HTS is typically administered via central vascular access due to the concern that if extravasation of the infusion occurs, tissue damage from cell implosion can occur

The IO route is generally accepted in resuscitation environments including the emergency department, EMS, and military settings with some authors recommending the IO as a primary method of obtaining emergency vascular access The adult advanced cardiac life support (ACLS) guidelines recommend either intravenous or IO access.

A number of studies have established the safety of IO administration of hypertonic solutions. Randomized adult pigs to IO 7.5% HTS, IO 3% HTS, and 0.9% isotonic saline and found regular tissue morphology, no necrosis or microscopic ischemic changes in the HTS groups. Several studies conducted to evaluate the efficacy of hypertonic solutions on resuscitation for hemorrhagic shock used the IO route and did not make note of problems arising from the administration of IO HTS. Another study using a canine model of hemorrhagic shock briefly mentioned transient lameness in the IO HTS group, but this resolved by 48 hours . While the majority of studies using hypertonic saline solutions did not make note of complications, one study induced hemorrhagic shock in dehydrated swine and resuscitated one group with 7.5% HTS and noted a high rate of local complications from soft tissue and bone marrow necrosis .

One study noted a subgroup of patients in which IO access was obtained on conscious patients. None of the patients received local anesthetic and none reported pain during insertion. Eighteen of the 22 conscious patients reported pain during fluid administration. Central venous catheter (CVC) placement is the current standard of care; even with local anesthesia it can be painful. Most of the potential subjects, due to the nature of their severe neurologic injury, may not be affected by the pain associated with IO fluid administration. Manufacturer literature suggests the use of lidocaine to anesthetize the bone before infusing if possible (Teleflex).

It is expected that utilizing IO for vascular access in the ICU will be safe and tolerable. If this study confirms the anticipated results, there are numerous implications. First, neurologically injured patients requiring emergent HTS may have faster access to this therapy. A study comparing IO to CVC access undergoing resuscitation in the emergency department found IO to be faster to insert (2.3 vs. 9.9 minutes) and had fewer failures to access on the first attempt. Second, serious complications from IO were absent compared with severe to life-threatening mechanical complications from CVC including pneumothorax, damage to the carotid artery, and bleeding which were cited at 0.7%-2.1% depending on site. And thirdly, central line associated blood stream infections (CLABSI) are a leading cause of hospital acquired infections in the ICU and are associated with higher mortality. CLABSI rates are measured by number of infections per 1,000 catheter days and shorter CVC dwell time is prudent. If a reliable and rapid source of vascular access could postpone or eliminate CVC insertion, risk of CLABSI may be reduced. These potential benefits outweigh the minimal expected risk.