Rapid Sequency Intubation Part 1

A new podcast on Rapid Sequence Intubation is available for free in the iTunes store. The podcast is a companion to the EMS Pharmacology book of the same name.

Ketamine is a great drug for EMS

Ketamine is perhaps one of my favorite drugs to use for care of the critically injured and yet it seems to have such a poor reputation in EMS. Ketamine is a drug that causes dense analgesia and maintains sympathetic tone, airway control, and respiratory drive. It is commonly used in Europe, the military, burn centers, and trauma centers.

It's use in prehospital care is very limited in the US. It is a cousin of LSD so it can cause some strange and vivid nightmares. Also it increases secretions. For these reasons when we use it we typically give a medication that decreases secretions such as robinol or atropine. Next a benzodiazepine such as versed or valium is given to cause antegrade amnesia. This will make it so the vivd dreams are not remembers. Then we administer the ketamine. It is a very dense anagesic so giving additional opiates is not required. Read more about this drug in my book on page 381.

JEMS Meeting

I recently presented several talks last week at the JEMS EMS meeting in Baltimore. I appreciated all the kind hellos and feedback everyone provided. I will be taking the talk on Cardiovascular physiology and converting that to a podcast hopefully this weekend.

Neurogenic Shock and Phenylephrine

Neurogenic shock occurs when loss of sympathetic tone from the brain or spinal cord causes the blood vessels to dilate. This in turn causes the vascular space to enlarge. If the patient doesn't loose a single drop of blood, this increase in the vascular space causes a hypovolemia that is relative to the newly enlarged vascular space. The initial treatment is the same as it is for all the other forms of shock. Fluids. Drug treatment for neurogenic shock is to increase the vascular tone of the blood vessels. This requires stimulation of the alpha adrenergic receptor. This is best done with the drug phenylephrine which is a pure alpha agonist. Other drugs that are sometimes used are dopamine or norepinephrine-- both of these drugs act on both alpha and beta-1 receptors.

Shock is a symptom not a disease

There are some very common errors when treating shock. The most common error is that shock is the presence of hypotension (low blood pressure). Not true. Shock occurs when there is inadequate oxygen delivery to vital organs such as the heart brain or kidney. Shock can occur with a normal blood pressure. In fact, the presence of a low blood pressure or rapid heart rate are considered LATE signs of shock. The other important consideration is that shock is only a symptom of a much bigger problem. A provider wants to treat the cause of shock not just the symptom of shock, eg. hypotension. If a patient has a low blood pressure from dehydration secondary to diabetic ketoacidosis, starting dopamine will increase the blood pressure, but it will actually DECREASE the blood flow and oxygen delivery to the vital organs. Said another way, the blood pressure will go up but the shock will be worse. In that case you need to treat the blood sugar and replace the fluids from the dehydration.

Listen to podcasts: www.prehospitalpharmacology.com

Mannitol

Mannitol is a sugar that is used as an osmotic diuretic. Diuretics are drugs the cause people to increase their urine output. Mannitol is unique in that it initially causes volume expansion and the water follows the mannitol as the molecule is filtered through the kidney. Mannitol is commonly used for the treatment of cerebral hypertension or increased intracranial pressure following head trauma. When to actually give mannitol in victims of head trauma has been a source of great discussion and controversy. The dilemma in the prehospital environment is the inability to look at a CT scan and characterize the injury. If the patient has active intracranial bleeding say from an epidural hematoma, the argument has been that administration of mannitol wil increase the bleeding and increase the mass lesions (blood collection). This has led to the recommendation that without the presence of a CT scan, the patient should have lateralizing signs to be considered for the administration of mannitol.

Mannitol is contraindicated in patients who are in anuric renal failure (ie. not making urine) or in patients with severe dehydration or hypovolemia. Also mannitol administration can lead to pulmonary edema in patients with congestive heart failure.

In cold temperatures that are often encountered in a prehospital environment, Mannitol may crystalize.

(keywords: mannitol, EMS, emergency, EMT, paramedic, prehospital pharmacology, PHTLS)

Vasopressin in ACLS

Some quick notes for the use of vasopressin in the use of ACLS. Vasopressin is one of drugs that actually has a name that makes some sense in that it is a vasopressor. Vasopressin is unique from epinephrine. Epinephrine uses the adreneric receptor and vasopressin uses a different receptor. Vasopressin can be used in VF and pulseless VT as a one time only dose of 40 units IV. Vasopressin is a potent vasoconstrictor and it does not increase oxygen consumption by the heart. It cannot be used in repeated dose like epinephrine. Vasopressin is effective even when the patient is acidotic. Remember for VT/VF epinephrine should be repeated at a dose of 1 mg every 3 to 5 minutes.

(keywords: vasopressin, ACLS, EMS, emergency, EMT, paramedic, prehospital pharmacology, PHTLS)