Clinical pearls of pharmacological restraints
- Advanced airway equipment and cardiac monitoring must be available if a patient is to be given chemical restraints.
- If a patient’s respiratory status declines, ALS providers must be able and willing to take over the airway to prevent hypoxia.
The decision to provide prehospital agitation management involves heavy consideration of the patient’s rights, clinical status and the necessity of prehospital intervention in the first place.
Learn more: Physical and chemical restraints in EMS: Ensuring safety and compliance
Following is a review of the chemical restraint options available to EMS.
Versed (midazolam)
Versed, also known as midazolam, is a potent benzodiazepine that is commonly used for emergent sedation, preoperative anxiolysis and sedation, and procedural sedation. Its main mechanism of action is through GABA agonism. It is a potent sedative-hypnotic medication. It is unique in that it induces anterograde amnesia, making it a feasible tool for EMS interventions, such as synchronized cardioversion. It is the first-line medication for terminating seizures in many EMS protocols.
Avoid using midazolam in any patients with a known HX of acute angle-closure glaucoma or in active shock. Midazolam does have vasodilatory effects and reduces sympathetic nervous system drive [4].
Midazolam (and all benzodiazepines) can induce paradoxical excitation. Signs of paradoxical excitation include agitation, increased aggression and erratic muscular movements. While no RCT is available exploring paradoxical excitation with midazolam use, a 2004 study on pediatrics found that 3.4% of the studied patient population receiving midazolam required ketamine as a second, adjunctive therapy after experiencing paradoxical excitation [2].
Stacking CNS depressant medications with alcohol can worsen CNS depression and prompt respiratory depression [4].
Routes: IV/IM/IN
Ativan (Lorazepam)
Lorazepam is another benzodiazepine that is similar in mechanism to midazolam. However, lorazepam does have a longer duration of action and may be less optimal than midazolam for prehospital sedation.
Routes: IV/IM/IN
Haloperidol
Haloperidol is a first-generation typical antipsychotic that is used for both long-term control of psychotic conditions, such as schizophrenia and acute agitation management. It is a dopamine (D2 receptor) competitive antagonist. It is commonly used in EMS protocols for the management of psychiatric disorder-related agitation and psychosis.
Haloperidol should not be used in elderly patients, especially those with dementia, or those with dopamine-deficient conditions, such as Parkinson’s disease. There is an increased risk of mortality with haloperidol use in the elderly [6]. Haloperidol can also result in a drug-induced form of Parkinsonism due to its dopamine-blocking effects.
Haloperidol is a QT-prolonging medication.
Dystonia is a significant side effect of antipsychotic use characterized by involuntary, spasmodic muscle contractions [6]. It is extremely unpleasant and sometimes painful for the patient. Tardive dyskinesia is also a concern with antipsychotic use.
Routes: IV/IM/Long-acting IM/PO
Benadryl (diphenhydramine)
Diphenhydramine is a 1st-generation antihistamine medication. It works via H1 histamine receptor antagonism, preventing the action of histamine. While not a mainline sedative in and of itself, it does still play a role in many EMS protocols nationwide in addition to ED sedation use.
Diphenhydramine crosses the blood-brain barrier and is a potent CNS depressant [8]. It has anticholinergic properties which make it suboptimal and potentially dangerous when stacking with other anticholinergic substances. For instance, monoamine oxidase A inhibitors, tricyclic antidepressants and diazepam are all anticholinergic medications.
Diphenhydramine is useful in reversing the effects of dystonia following sedation with antipsychotics [8].
Routes: IM, IV, PO
Ketamine
Ketamine is a dissociative-anesthetic medication with a wide variety of uses. It is commonly used for general sedation, procedural sedation, rapid sequence induction (RSI), and even as a rescue medication in severe bronchospasm.
Ketamine has a dose range that allows for a variety of effects. At lower dose ranges, it produces analgesia with some dissociation. At higher ranges, it can produce total anesthesia and an unconscious state. It is important that clinicians properly dose the patient for the scenario at hand to avoid over or undersedation.
Ketamine is known to induce episodes of tachycardia and hypertension that are often transient [7]. There is some debate in the medical community about its use in patients where hypertension would be a concern such as patients with head injuries/increased intracranial pressure and known vasculopathies [7].
Routes: IM/IV/IN
Chemical sedation choices
Deciding to provide invasive agitation management methods should be made with care and consideration. EMS clinicians have a unique role in public safety and medicine as first responders tasked with pharmacological sedation. EMS clinicians should exercise significant caution and tact when providing sedation and physical restraints.
Video: Treating agitated patients
References
1. Al-Halawani, R., Charlton, P., Qassem, M., & Kyriacou, P. A. (2023). A review of the effect of skin pigmentation on pulse oximeter accuracy. Physiological Measurement, 44(5), 05TR01.
2. Golparvar, M., Saghaei, M., Sajedi, P., & Razavi, S. S. (2004). Paradoxical reaction following intravenous midazolam premedication in pediatric patients - a randomized placebo controlled trial of ketamine for rapid tranquilization. Paediatric Anaesthesia, 14(11), 924–930.
3. Kupas, D. F., Wydro, G. C., Tan, D. K., Kamin, R., Harrell, A. J., & Wang, A. (2021). Clinical care and restraint of agitated or combative patients by emergency medical services practitioners. Prehospital Emergency Care, 25(5), 721–723.
4. Lingamchetty, T. N., Hosseini, S. A., & Saadabadi, A. (2023, June 5). Midazolam. StatPearls - NCBI Bookshelf.
5. Olejarczyk, J. P., & Young, M. (2022, November 28). Patient rights and ethics. StatPearls NCBI Bookshelf.
6. Rahman, S., & Marwaha, R. (2023, September 1). Haloperidol. StatPearls - NCBI Bookshelf.
7. Rosenbaum, S. B., Gupta, V., Patel, P., & Palacios, J. L. (2024, January 30). Ketamine. StatPearls - NCBI Bookshelf.
8. Sicari, V., & Zabbo, C. P. (2023, July 10). Diphenhydramine. StatPearls - NCBI Bookshelf.
9. Steinberg, A. (2021). Prone restraint cardiac arrest: A comprehensive review of the scientific literature and an explanation of the physiology. Medicine, Science and the Law/Medicine, Science and the Law, 61(3), 215–226.
