About Mike O'Brien, PharmD

ALiEM Series Editor, EM Pharm Pearls
EM Clinical Pharmacist
Massachusetts General Hospital

Simplified Dosing Scheme for DigiFab® in Acute Digoxin Poisoning

Simplified Dosing Scheme for DigiFab® in Acute Digoxin Poisoning

Background

Treatment of digoxin toxicity can be quite complex and generally involves the use of digoxin immune Fab (DigiFab®) for symptomatic patients. The dosing of DigiFab can vary depending on the amount ingested, serum concentration, and/or suspected chronicity of toxicity. Alternatively, for an acute ingested of an unknown amount where the serum concentration is not available, it is recommended that 10 vials of DigiFab be administered empirically. This antidote is expensive (~$5,000 per vial) and not always readily available in every hospital. Given the complicated dosing and cost, alternative dosing strategies are being explored.

Evidence

Researchers from Australia first proposed an initial 2-vial DigiFab dose for acute digoxin poisoning in a 2014 review article [1]. They followed this up with a pharmacokinetic study supporting the simplified dosing scheme [2]. Based on their early data, the Australian poison center recommendations were revised to instead use small doses of DigiFab (2 vials at a time) with repeat doses as needed to achieve clinical effect. This allowed them to prospectively study this new dosing strategy in 21 cases of digoxin toxicity [3]. Most patients required less than would have been administered following traditional dosing calculations. Patients receiving the lower-dosing scheme did have a rebound in free digoxin levels >2 ng/mL at a median time of 18 hours in patients with normal renal function and 103 hours in patients with an acute kidney injury. Most patients received 2 vials of DigiFab initially and a median of 4 vials total after receiving additional doses based on persistent or recurrent symptoms. Overall, patients required significantly less antidote with similar clinical outcomes. Importantly, there are limitations with the data to date, highlighted in a letter-to-the-editor (Mahonski 2021). This titration approach should only be considered with input from a toxicologist.

Characteristics and Savings
Amount of digoxin ingested*13 mg (9.5-25 mg)
Initial potassium*5 mEq/L (4.5-5.4 mEq/L)
Fatalities due to digoxin toxicity0
Estimated vials saved^223-356 vials
Estimated cost savings^†$1.1-1.8 million
* Median (IQR)
^ Difference between titrated dosing scheme compared to doses based on ingested amount and serum concentration
† Based on cost of $5000 per vial

Pearls

Following administration of DigiFab, avoid measurement of the total digoxin concentration as this measures both free drug and drug bound to DigiFab, which will cause the result to be falsely elevated [4]. Additionally, extracorporeal treatments are not recommended for the removal of digoxin or the digoxin-Fab complex, regardless of the clinical context.

Bottom Line

  • In select cases of acute digoxin poisoning, patients may safely receive 2 vials of DigiFab with repeat doses as necessary based on symptoms. If considering this treatment approach, it is recommended to consult with a toxicologist and/or pharmacist.
  • Total serum digoxin levels can be falsely elevated following the administration of DigiFab.

Want to learn more about EM Pharmacology?

Read other articles in the EM Pharm Pearls Series and find previous pearls on the PharmERToxguy site.

References

  1. Chan BSH, Buckley NA. Digoxin-specific antibody fragments in the treatment of digoxin toxicity. Clin Toxicol (Phila). 2014;52(8):824-836. doi: 10.3109/15563650.2014.943907. PMID: 25089630.
  2. Bracken LM, Chan BSH, Buckley NA. Physiologically based pharmacokinetic modelling of acute digoxin toxicity and the effect of digoxin-specific antibody fragments. Clin Toxicol (Phila). 2019;57(2):117-124. doi: 10.1080/15563650.2018.1503288. PMID: 30306803.
  3. Chan BS, Isbister GK, Chiew A, Isoardi K, Buckley NA. Clinical experience with titrating doses of digoxin antibodies in acute digoxin poisoning. (ATOM-6). Clin Toxicol (Phila). Published online August 23, 2021:1-7. doi: 10.1080/15563650.2021.1968422. PMID: 34424803.
  4. DigiFab®. Package insert. BTG International Inc; 2017.
  5. Mowry JB, Burdmann EA, Anseeuw K, et al. Extracorporeal treatment for digoxin poisoning: systematic review and recommendations from the EXTRIP Workgroup. Clin Toxicol (Phila). 2016;54(2):103-114. doi: 10.3109/15563650.2015.1118488. PMID: 26795743.
By |2021-11-01T12:44:15-07:00Oct 16, 2021|EM Pharmacy Pearls, Tox & Medications|

INR reduction with FFP – How low can you go?

Background

Bleeding patients or those undergoing procedures that are at high risk of bleeding may require correction of their INR. Multiple products can be used to achieve this, including fresh frozen plasma (FFP). FFP contains many substances, including clotting factors, fibrinogen, plasma proteins, electrolytes, and anticoagulant factors. It is sometimes said that the intrinsic INR of FFP is approximately 1.6-1.7 and that it’s not possible to achieve a lower INR. This pearl will further explore these concerns.

Evidence

  • What is the INR of FFP?
    • The mean INR of FFP appears to be ~1.1 (0.9-1.3) [1,2].
    • Reports that the intrinsic INR of FFP is 1.6-1.7 may be based on the clinical experience of not being able to achieve an INR <1.6-1.7 with FFP.
  • Is it possible to “normalize” the INR with FFP alone?
    • Several studies have found that it’s difficult to achieve an INR <1.7 with only FFP [3,4]. However, other studies were able to achieve lower average INR values [2,5,6]. 
    • Overall, these studies found that there was a significantly greater decrease in INR when the pre-FFP INR was higher, but there was a much smaller decrease when the INR was closer to the normal range.
  • Why does FFP appear to have diminishing returns when the pre-FFP INR is lower?
    • The relationship between the INR and percentage of clotting factors present in the blood is not linear (see figure) [7].
    • For example: An increase of ~5% in clotting factors may decrease the INR from 3 to 2.5 but the same amount of FFP may only reduce an INR of 1.7 to 1.6.

Figure 1: Adapted from Dzik  2012 [7].

    • Additionally, the table below also demonstrates that small volumes of FFP result in large changes when the initial INR is elevated, but very large amounts of FFP are required to achieve an INR of 1.3 no matter the initial INR (see table).
Amount of FFP to Achieve a Target INR Based on Pre-FFP INR
Target INR
1.31.73.0
Initial INRVolume (L)Dose (mL/kg)Factor (%)Volume (L)Dose (mL/kg)Factor (%)Volume (L)Dose (mL/kg)Factor (%)
6.04.564452.536251.52115
5.04.361432.332231.01410
4.04.057402.029200.575
3.03.550351.52115
2.02.536250.575

Table 1: Adapted from Holland 2006 [3]. Note: 1 unit of FFP is ~200-250 mL

    • Given the above data, the issue preventing the achievement of an INR <1.7 appears to be the dose/volume of FFP required and not the intrinsic INR of FFP.
  • Does the INR need to be <1.7 to achieve hemostasis?
    • Since the INR only provides limited information regarding a single aspect of anticoagulation status, complete normalization for the INR to control bleeding is usually not necessary [6].
    • An INR elevation alone does not indicate a patient is coagulopathic or at an increased risk of bleeding [7]. Additionally, an INR elevation in patients with liver dysfunction likely reflects an overall state of decreased factor production, both procoagulant and anticoagulant factors [8].
    • The target INR varies depending on multiple patient factors and planned interventions, but an INR of 1.0 is likely not necessary to prevent bleeding or achieve hemostasis.

Bottom Line

  • A unit of FFP has an INR of ~1.1, but this doesn’t mean it can easily normalize the INR.
  • There is a non-linear relationship between percentage of clotting factors and the INR, resulting in diminishing returns from each unit of FFP as the INR decreases.
  • Very large doses of FFP may be required to fully correct an elevated INR, which frequently precludes its use.
  • Complete normalization of the INR is not required to achieve hemostasis or prevent bleeding from a procedure.

Want to learn more about EM Pharmacology?

Read other articles in the EM Pharm Pearls Series and find previous pearls on the PharmERToxguy site.

References

  1. Holland LL, Foster TM, Marlar RA, Brooks JP. Fresh frozen plasma is ineffective for correcting minimally elevated international normalized ratios. Transfusion. 2005;45(7):1234-1235. doi: 10.1111/j.1537-2995.2005.00184.x. PMID: 15987373.
  2. Only AJ, DeChristopher PJ, Iqal O, Fareed J. Restoration of normal prothrombin time/international normalized ratio with fresh frozen plasma in hypocoagulable patients. Clin Appl Thromb Hemost. 2016;22(1):85-91. doi: 10.1177/1076029614550819. PMID: 25294634.
  3. Holland LL, Brooks JP. Toward rational fresh frozen plasma transfusion: The effect of plasma transfusion on coagulation test results. Am J Clin Pathol. 2006;126(1):133-139. doi: 10.1309/NQXH-UG7H-ND78-LFFK. PMID: 16753596.
  4. Abdel-Wahab OI, Healy B, Dzik WH. Effect of fresh-frozen plasma transfusion on prothrombin time and bleeding in patients with mild coagulation abnormalities. Transfusion. 2006;46(8):1279-1285. doi: 10.1111/j.1537-2995.2006.00891.x. PMID: 16934060.
  5. Müller MCA, Straat M, Meijers JCM, et al. Fresh frozen plasma transfusion fails to influence the hemostatic balance in critically ill patients with a coagulopathy. J Thromb Haemost. 2015;13(6):989-997. doi: 10.1111/jth.12908. PMID: 25809519.
  6. McCully SP, Fabricant LJ, Kunio NR, et al. The International Normalized Ratio overestimates coagulopathy in stable trauma and surgical patients. J Trauma Acute Care Surg. 2013;75(6):947-953. doi: 10.1097/TA.0b013e3182a9676c. PMID: 24256665.
  7. Dzik W “Sunny.” Reversal of drug-induced anticoagulation: old solutions and new problems. Transfusion. 2012;52(s1):45S-55S. doi: 10.1111/j.1537-2995.2012.03690.x. PMID: 22578371.
  8. Harrison MF. The misunderstood coagulopathy of liver disease: a review for the acute setting. West J Emerg Med. 2018;19(5):863-871. doi: 10.5811/westjem.2018.7.37893. PMID: 30202500.
By |2021-08-28T10:03:39-07:00Aug 21, 2021|EM Pharmacy Pearls, Heme-Oncology|

Beta-Blockers for Inhalant-Induced Ventricular Dysrhythmias

Background

There are a few unique scenarios when beta-blockers may be indicated for patients in cardiac arrest. Use of esmolol for refractory ventricular fibrillation was summarized in a 2016 PharmERToxGuy post with an accompanying infographic. Another potential use for beta-blockers is in the rare case of a patient with inhalant-induced ventricular dysrhythmias. The term ‘sudden sniffing death’ refers to acute cardiotoxicity associated with inhaling hydrocarbons. Check out this ACMT Toxicology Visual Pearl for more information about the background and diagnosis of inhalant abuse.

It is thought that inhalants causes myocardial sensitization via changes in various cardiac channels (e.g., sodium channels, potassium channels, calcium channels, or gap junctions) leading to prolonged repolarization and conduction [1, 2]. Additionally, chronic inhalant use can lead to structural heart damage. When the above alterations are combined with a sudden increase in catecholamines (e.g., exercise, caught sniffing), a dysrhythmia can develop which is often fatal [2-4].

Evidence

There are no case reports to support the use beta-blockers to treat inhalant-induced dysrhythmias. However, the case reports below include patients that ingested various hydrocarbons who developed ventricular dysrhythmias and improved following the initiation of beta-blockers. As the adverse cardiac effects should be similar between inhaled and ingested hydrocarbons, we can potentially extrapolate this data to patients with inhalant-induced dysrhythmias.

DemographicsAgent(s) Ingested Cardiac EffectsInterventionsResolution of dysrhythmia following BB?
39 yo M [5]TrichloroethylenepVT/VF arrestDefibrillation, Propranolol bolus and infusion

Y

70 yo F [6]TrichloroethyleneBigeminy, Junctional rhythmEsmolol bolus and infusion

Y

23 yo F [7]Chloral hydrateVF arrestEsmolol bolus and infusion

Y

27 yo M [8]Chloral hydrate, Loxapine, FluoxetineStable VTPropranolol bolus and infusion

Y

3 yo M [9]Chloral hydrateSinus tachycardia, Bigeminy, Trigeminy, NSVTEsmolol bolus and infusion

Y

44 yo M [10]Chloral hydrateStable VTPropranolol bolus, Labetalol infusion

Y

BB=beta-blocker; pVT=polymorphic ventricular tachycardia; VT=ventricular tachycardia; VF=ventricular fibrillation; NSVT=non-sustained ventricular tachycardia

Bottom Line

  • Patients presenting to the ED with cardiopulmonary manifestations of inhalant use should have routine electrolytes and an ECG to assess cardiac status
  • A quiet environment is important to decrease stimulation and minimize catecholamine surges
  • For both stable and non-perfusing dysrhythmias, propranolol or esmolol are reasonable choices to counteract the catecholamine effects, in addition to standard care [5-10]
    • Consider avoiding epinephrine and other catecholamines unless necessary, as they may worsen the dysrhythmia

Want to learn more about EM Pharmacology?

Read other articles in the EM Pharm Pearls Series and find previous pearls on the PharmERToxguy site.

References

  1. Nelson LS. Toxicologic myocardial sensitization. J Toxicol Clin Toxicol. 2002;40(7):867–79. doi: 10.1081/clt-120016958. PMID: 12507056.
  2. Tormoehlen LM, Tekulve KJ, Nañagas KA. Hydrocarbon toxicity: A review. Clin Toxicol (Phila). 2014 Jun;52(5):479–89. doi: 10.3109/15563650.2014.923904. PMID: 24911841.
  3. Bass M. Sudden sniffing death. JAMA. 1970 Jun 22;212(12):2075–9. PMID: 5467774.
  4. Baydala L. Inhalant abuse. Paediatr Child Health. 2010 Sep;15(7):443–54. doi: 10.1093/pch/15.7.443. PMID: 21886449.
  5. Gindre G, Le Gall S, Condat P, Bazin JE. [Late ventricular fibrillation after trichloroethylene poisoning]. Ann Fr Anesth Reanim. 1997;16(2):202–3. doi: 10.1016/s0750-7658(97)87204-8. PMID: 9686084.
  6. Mortiz F, de La Chapelle A, Bauer F, Leroy JP, Goullé JP, Bonmarchand G. Esmolol in the treatment of severe arrhythmia after acute trichloroethylene poisoning. Intensive Care Med. 2000 Feb;26(2):256. doi: 10.1007/s001340050062. PMID: 10784325.
  7. Shakeer SK, Kalapati B, Al Abri SA, Al Busaidi M. Chloral hydrate overdose survived after cardiac arrest with excellent response to intravenous β-blocker. Oman Med J. 2019 May;34(3):244–8. doi: 10.5001/omj.2019.46. PMID: 31110633.
  8. Zahedi A, Grant MH, Wong DT. Successful treatment of chloral hydrate cardiac toxicity with propranolol. Am J Emerg Med. 1999 Sep;17(5):490–1. doi: 10.1016/s0735-6757(99)90256-5. PMID: 10496517.
  9. Nordt SP, Rangan C, Hardmaslani M, Clark RF, Wendler C, Valente M. Pediatric chloral hydrate poisonings and death following outpatient procedural sedation. J Med Toxicol. 2014 Jun;10(2):219–22. doi: 10.1007/s13181-013-0358-z. PMID: 24532346.
  10. Wong O, Lam T, Fung H. Two cases of chloral hydrate overdose. Hong Kong Journal of Emergency Medicine. 2009 Jul;16(3):161–7. doi: 10.1177/102490790901600307.

One-Time Vancomycin Doses in the Emergency Department

Background

A previous ALiEM post from 2013 by an EM pharmacist colleague argued the case against one-time vancomycin doses in the ED prior to discharge. The take-home points from this post were:

    1. No evidence that a one-time vancomycin has any benefit
    2. This practice is not recommended by the Infectious Diseases Society of America (IDSA)
    3. May extend the patient’s ED stay by at least an hour for the IV infusion, depending on the dose
    4. Increases the cost of the ED visit (e.g., IV line, medication, RN time)
    5. Pharmacokinetically 1 dose of vancomycin doesn’t make sense
      • Vancomycin 1 gm IV x1 provides sub-therapeutic levels for patients with normal renal function
      • Efficacy is based on overall exposure (e.g., AUC/MIC) achieved with repeated dosing over several days
    6. Subtherapeutic vancomycin concentrations lead to development of resistance

Despite the above points, a one-time dose of vancomycin prior to the patient being discharged on an oral regimen is a common practice [1].

Evidence

As stated above, a single dose of vancomycin is unlikely to provide a therapeutic benefit and may only serve to reassure clinicians. The 2020 consensus guidelines regarding vancomycin monitoring for serious MRSA infections reinforce the recommendation of achieving an AUC0-24/MIC ratio of ≥400, as a ratio <400 increases resistance and has inferior efficacy [2]. Since the AUC is dependent on overall time of exposure plus concentration, a single dose for an average patient with normal renal function is not adequate (Figure 1). The graph below also demonstrates how long it generally takes for vancomycin to reach steady state when patients receive a dose every 8 hours.

 

*The estimated AUC above assumes a 30 yo male that weights 70kg and is 6′ tall with a serum creatinine of 1.0 mg/dL.

A randomized trial conducted at Christiane Care Health System compared patients who received a vancomycin loading dose of 30 mg/kg or 15 mg/kg [3]. Just twelve hours after this initial dose, 34.6% of patients who received 30 mg/kg had vancomycin levels in the therapeutic range (trough >15 mg/L) vs. 3% of patients who received 15 mg/kg (p < 0.01).

Bottom Line

Even large vancomycin loading doses rarely achieve therapeutic levels after one dose. Therefore, if the plan is to discharge, skip the one-time dose altogether and choose an antimicrobial regimen that will be continued in the outpatient setting (e.g., doxycycline or sulfamethoxazole/trimethoprim if concerned for MRSA or cephalexin for most other patients).

Want to learn more about EM Pharmacology?

Read other articles in the EM Pharm Pearls Series and find previous pearls on the PharmERToxguy site.

References

  1. Mueller K, McCammon C, Skrupky L, Fuller BM. Vancomycin use in patients discharged from the emergency department: a retrospective observational cohort study. J Emerg Med. 2015;49(1):50-57. doi: 10.1016/j.jemermed.2015.01.001. PMID: 25802166.
  2. Rybak MJ, Le J, Lodise TP, et al. Therapeutic monitoring of vancomycin for serious methicillin-resistant staphylococcus aureus infections: a revised consensus guideline and review by the american society of health-system pharmacists, the infectious diseases society of america, the pediatric infectious diseases society, and the society of infectious diseases pharmacists. Am J Health Syst Pharm. 2020;77(11):835-864. doi: 10.1093/ajhp/zxaa036. PMID: 32191793.
  3. Rosini JM, Laughner J, Levine BJ, Papas MA, Reinhardt JF, Jasani NB. A randomized trial of loading vancomycin in the emergency department. Ann Pharmacother. 2015;49(1):6-13. doi: 10.1177/1060028014556813. PMID: 25358330.

Safety and Efficacy of Clevidipine for Acute Blood Pressure Control

Background

Rapid and precise control of blood pressure is vital for patients with a hypertensive emergency or an acute stroke. Commonly, nicardipine is utilized in these situations, with nitroprusside being a less appealing alternative. The most recent AHA/ASA Acute Ischemic Stroke Guidelines, updated in 2019, also recommend clevidipine as a first-line antihypertensive option [1]. Clevidipine is a dihydropyridine calcium channel blockers, similar in mechanism to nicardipine and amlodipine. The main advantage of clevidipine over nicardipine is related to its pharmacokinetics (Table 1). Given its shorter half-life of elimination, clevidipine can be titrated every 1-2 minutes. Additionally, if hypotension does occur, stopping the clevidipine infusion allows blood pressure to rebound quickly.

MedicationOnsetDurationHalf-Life
Clevidipine2-4 mins5-15 mins1-15 mins
Nicardipine10-20 mins1-2 hours2-4 hours
Nitroprusside1-2 mins1-10 mins2 mins

Table 1: Pharmacokinetics of Common Antihypertensive Infusions [Micromedex; Lexicomp]

Evidence

Most studies demonstrate equivalent outcomes between clevidipine and other agents (e.g., nicardipine, nitroprusside, nitroglycerin) [2-5]. The ECLIPSE trial is the largest to assess the safety and efficacy of clevidipine [6]. The authors randomized cardiac surgery patients to clevidipine, nicardipine, nitroprusside, or nitroglycerin and found no difference in the incidence of myocardial infarction, stroke, or renal dysfunction. They noted that mortality was higher in patients receiving nitroprusside vs clevidipine, but equivalent compared to the the other medications. Additionally, clevidipine treated patients had significantly fewer excursions outside the prespecified blood pressure range than patients treated with any of the other agents.

Safety

Clevidipine is formulated in a 20% lipid emulsion and packaged in a glass vial. This causes clevidipine to appear similar to propofol, which could lead to safety issues. Also, care should be taken when using both clevidipine and propofol concomitantly, especially at high doses, as both provide clinically significant amounts of lipids, so triglycerides should be monitored.

Bottom Line

Clevidipine is a safe and effective antihypertensive to use in patients that require rapid and strict blood pressure control, specifically in patients with an aortic dissection or an acute ischemic/hemorrhagic stroke.

Want to learn more about EM Pharmacology?

Read other articles in the EM Pharm Pearls Series and find previous pearls on the PharmERToxguy site.

References

  1. Powers WJ, Rabinstein AA, Ackerson T, et al. Guidelines for the early management of patients with acute ischemic stroke: 2019 update to the 2018 guidelines for the early management of acute ischemic stroke: a guideline for healthcare professionals from the american heart association/american stroke association. Stroke. 2019;50(12):e344-e418. doi: 10.1161/STR.0000000000000211. PMID: 31662037.
  2. Allison TA, Bowman S, Gulbis B, Hartman H, Schepcoff S, Lee K. Comparison of clevidipine and nicardipine for acute blood pressure reduction in patients with stroke. J Intensive Care Med. 2019;34(11-12):990-995. doi: 10.1177/0885066617724340. PMID: 28820038.
  3. Rosenfeldt Z, Conklen K, Jones B, Ferrill D, Deshpande M, Siddiqui FM. Comparison of nicardipine with clevidipine in the management of hypertension in acute cerebrovascular diseases. J Stroke Cerebrovasc Dis. 2018;27(8):2067-2073. doi: 10.1016/j.jstrokecerebrovasdis.2018.03.001. PMID: 29627171.
  4. Ulici A, Jancik J, Lam TS, Reidt S, Calcaterra D, Cole JB. Clevidipine versus sodium nitroprusside in acute aortic dissection: A retrospective chart review. Am J Emerg Med. 2017;35(10):1514-1518. doi: 10.1016/j.ajem.2017.06.030. PMID: 28669696.
  5. Brehaut SS, Roche AM. Abstract W P65: Clevidipine Outperforms Other Agents in Emergent Acute Hypertension Treatment in Ischemic Stroke Pre-rt-PA. 2015;46:AWP65. doi: 10.1161/str.46.suppl_1.wp65.
  6. Aronson S, Dyke CM, Stierer KA, et al. The ECLIPSE trials: comparative studies of clevidipine to nitroglycerin, sodium nitroprusside, and nicardipine for acute hypertension treatment in cardiac surgery patients. Anesth Analg. 2008;107(4):1110-1121. doi:10.1213/ane.0b013e31818240db. PMID: 18806012.

Droperidol for Agitation in Older Adults in the Emergency Department

Droperidol is safe and effective for the treatment of severely agitated patients in the ED [1-3]. But what about its use for agitation in elderly patients specifically?

Droperidol Efficacy

Two Australian studies evaluated droperidol in more than 200 older adults (≥ 65 years old) in the prehospital and ED settings [4,5]. Both studies found droperidol to be effective in elderly patients with acute behavioral disturbances. The median time to sedation was ~20-30 minutes with doses ranging from 2.5-10 mg (Table 1). 

CharacteristicPage, et al (n=162)Calver, et al (n=47)
Median Age78 years81 years
Initial Droperidol IM Dose5 mg10 mg (n=30)
5 mg (n=15)
2.5 mg (n=2)
Median Time to Sedation19 mins10 mg: 30 mins
5 mg: 21 mins
2.5 mg: NA
Patients Sedated with ≤ 10 mg Droperidol144 (89%)34 (72%)

Table 1: Efficacy of droperidol in older adults

Droperidol Safety

Additionally, each study broke down each time a patient experienced an adverse event (Table 2). Overall, these adverse events were uncommon (4.5%), mild in nature, and resolved spontaneously or with minor interventions. No patients developed Torsades de Pointes. 

StudyAge/SexDroperidol DoseAdverse EventsManagementTime Post-Droperidol
Page, et al (n=162)76 yo Male5 mgSBP <90 (88/54)Spontaneous Resolution
87 yo Female10 mgSBP <90 (80/46)Spontaneous Resolution
79 yo Female5 mgSBP <90 (83/48)
O2 sat <90% (80%)
Supplemental Oxygen
500 mL IV Fluid
82 yo Male5 mgRR <12 (RR 10)Spontaneous Resolution
86 yo Male5 mgO2 sat <90% (88%)Supplemental Oxygen
Calver, et al (n=49)75 yo Male10 mgSBP <9030 mins
68 yo Female10 mgSBP <905 mins
73 yo Male10 mgAirway Obstruction100 mins
87 yo Female2.5 mgOversedation480 mins

Table 2: Safety of droperidol in older adults

Bottom Line

Taking the above points into account, droperidol appears to be both effective and safe in agitated adults ≥ 65 years of age for the treatment of agitation. The study authors recommend starting with 5 mg and repeating, if necessary, rather than initially using a dose of 10 mg.

Want to learn more about EM Pharmacology?

Read other articles in the EM Pharm Pearls Series and find previous pearls on the PharmERToxguy site.

References

  1. Perkins, J., Ho, J. D., Vilke, G. M., & DeMers, G. (2015). American academy of emergency medicine position statement: Safety of droperidol use in the emergency department. The Journal of Emergency Medicine, 49(1), 91–97. doi: 10.1016/j.jemermed.2014.12.024. PMID: 25837231.
  2. PharmERToxGuy. Onset of IM Medications for Severe Agitation. Posted Dec 12, 2019.
  3. PharmERToxGuy. QTc Prolongation and Torsades de Pointes with Droperidol in the Emergency Department. Posted Aug 30, 2020.
  4. Calver, L., & Isbister, G. K. (2013). Parenteral sedation of elderly patients with acute behavioral disturbance in the ED. The American Journal of Emergency Medicine31(6), 970–973. doi: 10.1016/j.ajem.2013.03.026. PMID: 23685060.
  5. Page, C. B., Parker, L. E., Rashford, S. J., Kulawickrama, S., Isoardi, K. Z., & Isbister, G. K. (2020). Prospective study of the safety and effectiveness of droperidol in elderly patients for pre-hospital acute behavioural disturbance. Emergency Medicine Australasia: EMA32(5), 731–736. doi: 10.1111/1742-6723.13496. PMID: 32216048.

Is Lactated Ringer’s Solution Safe for Hyperkalemia Patients?

Is Lactated Ringer's Solution Safe for Hyperkalemia Patients?

Background

There are three primary fluids used for resuscitation, each contains varying amounts of potassium per liter (Table 1):

  • 0.9% Sodium Chloride (normal saline)
  • Lactated Ringer’s solution
  • Plasma-Lyte A

Additionally, these fluids contain markedly different amounts of other electrolytes, some of which directly influence their pH (Table 1).

SolutionNa*Cl*K*Ca*Lactate*Acetate*Osmolarity^pH
Sodium Chloride 0.9% (normal saline)1541543085.5
Lactated Ringer’s13010942.7282736.5
Plasma-Lyte A140985272947.4
Blood135-14596-1063.5-58.5-10.50-1NA275-2957.35-7.45

Table 1: Characteristics of IV fluids vs blood [1-3] (* = mEq/L; ^ = mOsmol/L); note: this is not an exhaustive list of fluid contents

A common question is if the balanced fluids containing potassium (Lactated Ringer’s and Plasma-Lyte A) are safe to use in hyperkalemia patients. The answer is YES! Despite containing potassium, these fluids will still decrease the serum potassium level of a hyperkalemic patient. This is because the potassium concentration in these fluids is lower relative to the patient’s serum potassium level and dramatically lower than the patient’s intracellular potassium concentration.

Evidence

A secondary analysis of the SMART trial did not find a difference in severe hyperkalemia (K ≥7 mEq/L) in hyperkalemic patients that received a balanced fluid (8.5%) vs those that received normal saline (14%) (p=0.24) [4]. The authors concluded that:

Our results suggest that the acid-base effects of isotonic crystalloids are more important for potassium homeostasis than the relatively small amount of potassium in these fluids.

A breakdown of the SMART Trial secondary analysis by Journal Feed summarizes other major findings and concludes, “It’s reasonable to choose LR to treat hyperkalemia over NS.” Lastly, Dr. Josh Farkas provides a succinct summary of this topic in a 2014 EMCrit/Pulmcrit post which is helpful in understanding the interplay between fluid balance and the different replacement options. Additionally, he discusses the potential for normal saline to cause a non-anion gap metabolic acidosis thereby leading to increased serum potassium levels.

Bottom Line

Balanced fluids (Lactated Ringer’s and Plasma-Lyte A) containing potassium can safely be used in patients with hyperkalemia. Given their more neutral pH, they may be preferred over normal saline in some patients.

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References

  1. Sodium Chloride Injection. Package Insert. Baxter Healthcare Corporation; 2013.
  2. Lactated Ringers Injection. Package Insert. Baxter Healthcare Corporation; 2019.
  3. Plasma-Lyte A Injection. Package Insert. Baxter Healthcare Corporation; 2019.
  4. Toporek, A. H., Semler, M. W., Self, W. H., Bernard, G. R., Wang, L., Siew, E. D., Stollings, J. L., Wanderer, J. P., Rice, T. W., Casey, J. D., & SMART Investigators and the Pragmatic Critical Care Research Group. (2021). Balanced crystalloids versus saline in critically ill adults with hyperkalemia or acute kidney injury: Secondary analysis of a clinical trial. American Journal of Respiratory and Critical Care Medicine. doi: 10.1164/rccm.202011-4122LE. PMID: 33503391.

 

By |2021-04-05T08:06:09-07:00Apr 10, 2021|EM Pharmacy Pearls, Tox & Medications|
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