A Randomized Control Equivalence Study of Emergency Medical Services Use of Isopropyl Alcohol Aromatherapy Versus Ondansetron for Treatment of Pre-hospital Nausea

Nausea is a common symptom encountered in the Emergency Medical Services (EMS) environment that is often treated with oral or intravenous anti-emetic medications. Post operative patients with modern anesthesia techniques and processes still have a 20-30% incidence of Nausea and/or vomiting. Nausea is a complicated symptom that is though to arise from the vomiting center in the lateral reticular formation in the brainstem. Afferent inputs form the cerebellum, higher cortical centers, the vestibular apparatus, the glossopharyngeal nerve and the vagal nerve inputs contribute to the process of the perception of nausea. Chemoreceptors in the Chemoreceptor Trigger Zone (CTZ) are located on the brain surface and are highly vascularized leading to increased exposure to neurotransmitters such as Serotonin (5-HT-3), histamine (H1) acetylcholine and dopamine. Blocking such neurotransmitter stimulation with targeted medications such as antihistamines or 5-HT-3 antagonists such as Ondansetron.

Nausea is a common symptom encountered in the Emergency Medical Services (EMS) environment that is often treated with oral or intravenous anti-emetic medications. Many patients do not respond well to this therapy, and EMS services that have only basic life support (BLS) capabilities may not have any good treatment currently. Additionally, because of the configuration of modern day ambulances, the patient is transport in a rear facing position in the patient compartment with very limited view of the environment. This method of transport frequently causes motion sickness.

Motion sickness is thought to be caused by inadequate adaption of the body to conflicts between vestibular, visual, other proprioceptive inputs and inhibition of the vestibular cerebellum. Common therapies may include antihistamines, benzodiazepines, tricyclic antidepressants and or scopolamine. Behavioral strategies such a watching the true horizon, steering the vehicle, tilting head into turns and laying down with eyes closed have been shown to alleviate some symptoms of motion sickness. But these strategies are not available in the EMS environment. Scopolamine administered well before motion stimulus has been shown to prevent motion sickness and acute treatment is best when using sedating antihistamines. Non-sedating antihistamines, Ondansetron and ginger root have not been found to effectively prevent nor treat motion sickness.

Multiple agents have been studied for the treatment of nausea in the emergency department with equivalency of effect and time on onset. Common agents include ondansetron, metoclopramide, promethazine and prochlorperazine. Such agents have also been used in the EMS environment to some degree, but require parenteral administration with exposure to the risks for side effects or sedation. There are also not options at the BLS level. Post-operative oxygen therapy has not been shown to decrease post nausea after c-section delivery which is disappointing as this is a ubiquitous therapy in the EMS environment of care, is inexpensive and easy to administer. Ondansetron has been shown to be safe and effective in the prehospital environment with a low incidence of side effects but cost and need for parenteral administration is often a barrier to care.

Multiple studies have shown Isopropyl Alcohol (IPA) 70% aromatherapy to be as effective as Ondansetron with a more rapid onset of nausea relief. This therapy was performed by holding a folded saturated 70% IPA pad under the nares with the patient inhaling the vapors. The patient is simply instructed to take three deep breaths through their nose. In animal experiments, toxicity from inhalation of IPA is very low at doses allowable by inhalation as compared with dermal or oral ingestion. Dermal application of IPA is routinely used by EMS personnel to cleanse the area of skin immediately surrounding the insertion point of an intravascular catheter for medication administration, or blood draw.