What Current Studies Mean to EMS

Needle Size for Thoracostomy
Zengerink I, Brink PR, Laupland KB, et al: ˙Needle thoracostomy in the treatment of a tension pneumothorax in trauma patients: What size needle?ÓJournal of Trauma. 64(1):111Ï114, 2008.

To emergently release a tension pneumothorax, many EMS providers are trained to insert a 14-gauge needle with sheath. However, previous articles have demonstrated a failure rate as high as 40%, possibly due to insufficient length of the needle/sheath. The standard 14-gauge needle has a needle length of 5 cm and a sheath length of 4.5 cm. These authors set out to determine if the average tissue depth in the general population at the second intercostal space mid-clavicular lineÆ’the correct placement for needle decompressionÆ’is less than 5 cm.

A total of 774 thoracic CT scans of trauma patients were reviewed and measurements of chest wall thickness at the intended insertion site were recorded. The authors found that approximately 10% of men under 40 years of age exceeded needle length, and this number rose to nearly 20% for men over age 40. In women, approximately 33% under age 40 exceeded the minimum depth of 5 cm, with the number dropping to 25% for women over age 40. The authors also found that in a small segment of the population (less than 2.5%) the standard needle/sheath could penetrate the myocardium.

There’s no other option for needle decompression. It may be tempting to think about stocking a longer needle/sheath, but the possibility of striking the pulmonary artery, subclavian artery or vein, or producing a cardiac tamponade isn’t worth the risk. If you practice the technique, be aware that you may fail in a certain percentage of the population.

Identifying Basal Skull Fractures
McNicholl B: ˙Basal skull fractures delay coagulation.ÓInjury. 39(1):134Ï135, 2008.

Bleeding from the ear of a trauma patient can mean several things: basal skull fracture, tympanic membrane rupture, scalp laceration with pooling in the ear or trauma to the external auditory canal. If it’s a basal skull fracture, most providers would expect to see Battle’s sign. But it often takes hours for Battle’s sign to develop. This author proposes that determining the presence of a basal skull fracture may be as simple as checking to see if the blood clots.

Using a convenience sample of trauma patients, the author aspirated blood from the external ear and found that even after 20 minutes, it didn’t clot in patients with a confirmed basal skull fracture. If left in the ear, the blood was noted to form a sticky pool that slowly developed a crust. Bleeding from any other location that could drip into the external ear would solidify quickly. It didn’t seem to matter if the blood was mixed with cerebral spinal fluid or not; bleeding from a basal skull fracture still didn’t clot.

Assuming that all ear bleeding is from a basal skull fracture necessitates that the patient undergo an extensive workup; waiting until you see a Battle’s sign will be too late, and not taking the correct precautions when bleeding is basal puts the patient at risk. Next time, look at blood in the external ear of a trauma patient, and see if you can tell whether it’s from a basal skull fracture.

Is IO Equal to Iv?
Von Hoff DD, Kuhn JG, Burris HA, Miller LJ: ˙Does intraosseous equal intravenous? A pharmacokinetic study.Ó American Journal of Emergency Medicine. 26(1):31Ï38, 2008.

Most EMS agencies and emergency departments (EDs) use intraosseous (IO) access when it’s impossible to find a functional vein in a timely manner. What was once used exclusively in pediatrics is now widely used and accepted in adults. But does the amount of medication administered intraosseously equal the amount delivered through the IV? That was the premise for this study.

The authors administered equal amounts of morphine through an IO port and through a traditional IV to adult cancer patients. Blood was drawn at set intervals following administration to watch the blood levels rise, indicating bioavailability of the drug. Each patient received the medication both ways to increase the validity of the results. The authors found that the same amount of medication was recorded in the blood, independent of the way the medication was administered.

This type of study confirms what many of us who have used an IO already thoughtÆ’delivering medication through an IO doesn’t affect the amount of drug delivered to the patient.

Cooling Measures Using IV Fluids
Moore TM, Callaway CW, Hostler D: ˙Core temperature cooling in healthy volunteers after rapid intravenous infusion of cold and room temperature saline solution.ÓAnnals of Emergency Medicine. 51(2):153Ï159, 2008.

It’s becoming more evident that we need a way to cool patients who have suffered cardiac arrest, stroke or maybe spinal cord injury to improve their outcomes. How we accomplish this in the field has been the subject of debate. One way is to utilize cold saline. But the extent of cooling, provided by the rapid infusion of cold fluids hasn’t been quantified, at least until now.

These authors studied 16 subjects who received either cold or room temperature fluids. The study protocol called for the subjects to receive one liter of fluid, either cold or room temperature, over a 30-minute period. Their vital signs, as well as core and skin temperatures, were recorded every two minutes during the infusion. The authors found that infusion of cold fluid could reduce core temperature by one degree centigrade without causing significant changes in skin temperature or inducing the body’s hypothermic response.

This type of study is what EMS is all aboutÆ’improving the quality of life after serious illness or injury. Initiating the infusion of cold saline prior to arrival in the ED can go a long way to improving the likelihood of saving neurologic function. Talk to your medical director and your local hospitals about including this in your protocols for neurologically impaired individuals.

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