Tachydysrhythmia | SWORBHP Ask MAC

July 7, 2017 SWORBHP Category: Tachydysrhythmia, Adult Analgesia | Date: 7-Jul-2017

Question: This question may be a very rare situation but I have not been able to get an answer from any paramedics I have asked. As per the "Patching" section in the introduction of the ALS PCS the literature states "BHP cannot be reached despite reasonable attempts by the paramedic to establish contact, a paramedic may initiate the required treatment without the requisite online authorization if the patient is in severe distress and, in the paramedic’s opinion, the medical directive would otherwise apply". In a situation where a cardioversion is required and the unstable patient is still conscious, it is fairly common practice to ask for sedation and pain control (i.e. Morphine/Midazolam) along with orders for cardioversion. If multiple BH patches cannot be completed and in the paramedics opinion cardioversion is required for the unstable but conscious patient, are we able to administer sedation and pain control? I ask this because there is not a directive that directly deals with pain and sedation prior to delivering the cardioversion, but is common to ask for such direction.

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Answer: Thanks for this question. There is no definite criteria that would constitute a patch failure. This is an instance in which paramedic judgment must come into play. If two or three unsuccessful patch attempts have been made, and in your judgment the patient is at risk for serious harm with further delay in care, then you would be right in carrying out a treatment (cardioversion for unstable tachycardia in this case).

This scenario in particular, however, can be problematic. Additional agents that may be used for analgesia and sedation can result in hypotension and respiratory depression as common side effects. The purpose behind using your judgment in order to carry out a treatment prior to completion of a BHP patch is to prevent serious deterioration or harm to a patient as a result of a time-sensitive medical issue. Administering analgesia and sedation doesn’t necessarily fall into the same category as time-sensitive. The administration of those medications may help with comfort but in an already unstable patient might actually cause further harm.

In the unlikely event that you have a patch failure with a patient who needs cardioversion who is unstable, paramedic judgement is required. If the patient requires medication for sedation due to maintained level of consciousness, this most likely reflects adequate perfusion to allow time for either successful patch connection with the BHP or transport if transport times are relatively short. If the paramedic judges that the patient does not require analgesia or sedation due to altered LOC, this most likely represents poor perfusion and cardioversion would be appropriate and a patch to a BHP as soon as possible.

The Regional Base Hospital would not routinely support sedation and or analgesia without a patch prior to cardioversion. However every call is different and these scenarios can be dynamic. If the patch attempt fails and the paramedic judges the patient is too unstable to wait for transport or a successful patch AND requires some analgesia /sedation prior to cardioversion AND will tolerate the adverse effects of sedation / analgesia the paramedic may proceed with sedation / analgesia and subsequent cardioversion. The situation should be well documented on the ACR and BHP contact should be made as soon as possible. Again the call you describe would be a very unlikely situation.

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September 29, 2016 SWORBHP Category: Tachydysrhythmia | Date: 29-Sep-2016

Question: In reviewing literature addressing treatment and management of tachyarrhythmias, I've encountered several articles stating that lidocaine and amiodarone are contraindicated for treatment of Torsades de Pointes as they could prolong the QT interval and worsen the situation. However, our medical directives for ventricular tachycardia make no mention of this contraindication and make no distinction in the management of VT vs TdP. Recognizing that lidocaine as a Class I antiarrythmic would be worse for the patient than amiodarone (Class III) and that amiodarone is the preferred drug in our protocols for VTach, should we nonetheless be concerned with the use of either of these in managing TdP? Thanks for providing the forum in which to ask and share with colleagues.

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Answer: Great questions – to answer this we have to dive deep into physiology. The short answer is that sodium channel blocker action (Class I effect), like lidocaine, itself does not cause torsades de pointe (TdP). It is the QT-interval increasing action that typically causes this phenomenon. Acute treatment with amiodarone does not have the QT-interval increasing effects that long-term use does. So, it’s use in pre-hospital care is safe from this perspective.

For the longer, deeper dive into physiology: Amiodarone is an interesting and complex drug. It has both inward sodium (Vaughan-Williams class I effect) as well as inward calcium current (Vaughan-Williams class IV effects) as well as beta-blockade effect (Vaughan-Williams class II effect) and finally inhibition of outward potassium currents (Vaughan-Williams class III effect). It is this final class effect that would result in prolonged QT interval and a potential for TdP and other malignant ventricular arrhythmias. However, acute amiodarone therapy only acts on the Class I, II, and IV mechanisms. It’s class III effects are seen with chronic use.

As for class I agents causing TdP, there is a certain type of genetic abnormality, called Brugada syndrome, that can cause malignant rhythms, such as TdP. It is caused by abnormality in sodium channels. So, adding another sodium channel blocking medication in this particular scenario, may cause TdP. However, it is beyond the scope of our pre-hospital treatment to recognize and treat this rare phenomenon, while lidocaine has proven benefit in treating ventricular arrhythmias including TdP. In summary: there is a small population at risk for worsening of TdP, however the benefit outweighs the risk as a whole and either amiodarone or lidocaine should be used in the management of tachydrysrythmias per the Medical Directive.

References:

Postema PG, Wolpert C, Amin AS et al. Drugs and brugada syndrome patients: review of the literature. Recommendations and an up-to-date website. Heart Rhythm. 2009 Sep;6(9):1335-1341.

Roen DM. Cellular basis of drug-induced torsades de pointes. Br J Pharmacol. 2008 Aug;154(7):1502-1507

Sorajja D, Munger TM, Shen, W. Optimal antiarrhythmic drug therapy for electrical storm. J Biomed Res. 2015;29(10):20-34

Tarabar AF, Hoffman RS, Nelson LS. Citalopram overdose: Late presentation of torsades de pointes (TdP) with cardiac arrest. J Med Toxicol. 2008 Jun;4(2):101-105.

Van Herendael H & Dorian P. Amiodarone for the treatment and prevention of ventricular fibrillation and ventricular tachycardia. Vasc Health Risk Manag. 2010;6:465-472

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