Are Thrombolytics Safe for Acute Ischemic Strokes in Patients on DOACs?

Background

Direct-acting oral anticoagulants (DOACs), including apixaban, rivaroxaban, edoxaban, and dabigatran, are widely used for various indications and considered first-line therapy for prevention of acute ischemic stroke in patients with nonvalvular atrial fibrillation [1]. The management of acute ischemic stroke in patients on DOACs presents a difficult clinical scenario in the emergency department due to concern for increased risk of hemorrhage. IV thrombolytics (e.g., alteplase, tenecteplase), a mainstay in acute ischemic stroke management, are not recommended in current guidelines for patients whose last DOAC dose was within the last 48 hours [2, 3]. Therefore, patients with an acute ischemic stroke who are compliant with their DOACs are often excluded from guideline recommended therapy. Additionally, as covered in a previous ALiEM post, it is not recommended to reverse anticoagulation status in order to administer a thrombolytic.

Evidence

The use of IV thrombolytics in patients on DOACs was evaluated by Kam et al in a 2022 study published in JAMA [4]. This retrospective analysis included 163,038 patients from the AHA/ASA Get With The Guidelines-Stroke registry with acute ischemic stroke who received IV alteplase within 4.5 hours of symptom onset. Of the total number of patients, only 2207 had documented use of a DOAC within the last 7 days, with 25 of these patients reporting DOAC use within 48 hours. Patients on warfarin or other anticoagulants were excluded. The primary outcome was symptomatic intracranial hemorrhage (ICH) within 36 hours of IV alteplase administration. After adjusting for clinical factors, the rate of symptomatic ICH was not significantly different between patients taking DOACs and those not on anticoagulation (3.7% vs. 3.2%, adjusted OR 0.88, 95% CI 0.70 to 1.10). However, when stratified based on time from last DOAC dose, patients who took their DOAC 0-48 hours prior had an 8% rate of symptomatic ICH compared to 3.2% among those not on DOACs. Furthermore, the rate of any alteplase complication was 12% vs. 6% in those taking DOACs within 48 hours vs. no DOAC.

Limitations

  • The population at highest risk for bleeding is patients who took a DOAC within the last 48 hours, and this study only included 25 such patients.
    • A similar study tried to answer the same question for warfarin patients with an INR between 1.5-1.7. They also failed to include enough patients to make any definitive conclusions. [5]
  • Timing from the last DOAC dose was given as a range, with the majority of patients reporting use sometime within the last 7 days. It has been established in current AHA/ASA guidelines that receipt of DOACs past 48 hours prior is considered safe for thrombolytic administration, and if the included institutions were following current recommendations, thrombolytics were likely administered mostly to patients outside the 48-hour window.
  • Large potential for selection bias, since it was reported that almost 23,000 patients on DOACs from the original registry (who were otherwise eligible) did not receive thrombolytics.
  • Not clear how patients were determined to be on DOACs or if the authors were able to confirm this in unresponsive/intubated/deceased patients retrospectively. This could have resulted in DOAC patients being included in the non-DOAC group, which could have falsely evened-out the bleeding rates.

Bottom Line

  • The management of acute ischemic stroke in patients receiving prior anticoagulation presents a challenging clinical scenario.
  • Studies to date fail to include enough patients to evaluate the true risk of bleeding.
  • This study supports the current guideline recommendation to avoid alteplase in patients receiving a DOAC within 0-48 hours due to the increased risk of intracranial hemorrhage.

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. January CT, Wann LS, Calkins H, et al. 2019 AHA/ACC/HRS focused update of the 2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation. Published correction appears in Circulation. 2019;140(6):e285. Circulation. 2019;140(2):e125-e151. doi: 10.1161/CIR.0000000000000665. PMID: 30686041.
  2. 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.
  3. Berge E, Whiteley W, Audebert H, et al. European Stroke Organisation (ESO) guidelines on intravenous thrombolysis for acute ischaemic stroke. Eur Stroke J. 2021;6(1):I-LXII. doi: 10.1177/2396987321989865. PMID: 33817340.
  4. Kam W, Holmes DN, Hernandez AF, et al. Association of Recent Use of Non-Vitamin K Antagonist Oral Anticoagulants With Intracranial Hemorrhage Among Patients With Acute Ischemic Stroke Treated With Alteplase. JAMA. 2022;327(8):760-771. doi:10.1001/jama.2022.0948. doi: 10.1001/jama.2022.0948. PMID: 35143601.
  5. Xian Y, Liang L, Smith EE, et al. Risks of intracranial hemorrhage among patients with acute ischemic stroke receiving warfarin and treated with intravenous tissue plasminogen activator. JAMA. 2012;307(24):2600-2608. doi:10.1001/jama.2012.6756. doi: 10.1001/jama.2012.6756. PMID: 22735429.

 

Primary author:

Jessica Mason, PharmD

PGY-2 Emergency Medicine Pharmacy Resident

Massachusetts General Hospital

Blood Pressure Differences in Patients with Acute Aortic Dissections

Background

An acute aortic dissection (AAD) can be a life-threatening emergency which frequently requires rapid and precise control of the patient’s heart rate and blood pressure. The 2010 guidelines for management of patients with thoracic aortic disease suggest a heart rate goal of <60 bpm and a systolic blood pressure between 100-120 mmHg. In order to achieve this, a rapid-acting beta-blocker (i.e., esmolol) may be used in combination with an IV calcium channel blocker (i.e., nicardipine or clevidipine). These medications need to be monitored closely to avoid overshooting these goals and causing hemodynamic compromise. Ideally, an arterial line would be used to monitor the patient’s blood pressure, however this may not always be feasible so a traditional, noninvasive blood pressure cuff can be used. This may be complicated if the patient has the classic, but not universal, finding of unequal systolic blood pressure values between their left and right extremities. This raises the question, in a patient with an AAD and disparate blood pressures in each arm, which arm reading should be used for monitoring?

Evidence

A 2018 study from Um et al. evaluated 111 patients with an AAD and compared them with 111 control patients. This study found that while a systolic blood pressure difference of >20 mmHg between sides was a positive predictor for an AAD, the presence of a pulse deficit had a higher diagnostic accuracy. For the purpose of this study, a pulse deficit was defined as “any recorded difference in volume/force or difference in obvious signs of malperfusion”. The cause of an unequal blood pressure or pulse deficit in the upper extremities in this population is typically due to dissection of the brachiocephalic or subclavian arteries. In order to properly achieve the desired blood pressure reduction in patients with divergent blood pressure values, the higher value should be used for titration of antihypertensives. This is due to the occurrence of pseudohypotension occurring in the limb with the dissected artery.

Bottom-line

  • Aggressive and precise heart rate and blood pressure control are critical for patients with an acute aortic dissection
  • The presence of a pulse deficit may provide better diagnostic accuracy than a difference in systolic blood pressure
  • When titrating blood pressure medications in patients with unequal blood pressure readings between extremities, the higher value should be utilized

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. Hiratzka LF, Bakris GL, Beckman JA, et al. 2010 ACCF/AHA/AATS/ACR/ASA/SCA/SCAI/SIR/STS/SVM guidelines for the diagnosis and management of patients with thoracic aortic disease Circulation. 2010;121(13):e266-369. doi: 10.1161/CIR.0b013e3181d4739e. PMID: 20233780.
  2. Um SW, Ohle R, Perry JJ. Bilateral blood pressure differential as a clinical marker for acute aortic dissection in the emergency department. Emerg Med J. 2018;35(9):556-558. doi: 10.1136/emermed-2018-207499. PMID: 30021832.
By |2022-03-18T07:53:35-07:00Mar 19, 2022|Cardiovascular, EM Pharmacy Pearls|

Extracorporeal Treatment Options in Poisoned Patients

Background

Caring for a patient that is critically-ill secondary to a toxic ingestion is complicated and, in severe cases, extracorporeal treatments (ECTRs) may be considered. The most commonly used ECTRs are intermittent hemodialysis (iHD) and continuous renal replacement therapy (CRRT), but ECTRs also include exchange transfusion, hemoperfusion, liver dialysis, and therapeutic plasma exchange. Finding and evaluating the supporting literature for these treatment modalities in a timely manner is not feasible in most situations. In order to assist in this effort, the EXtracorporeal Treatments In Poisoning (EXTRIP) workgroup has reviewed and provided free, evidence-based recommendations regarding the use of ECTRs for many common toxins and toxicants [1]. These recommendations can be found in a summarized format on the EXTRIP website and the links to their comprehensive reviews are published on PubMed with direct links on their website. This international workgroup is made up of experts in toxicology, nephrology, emergency medicine, pediatrics, pharmacology, critical care, and more. An excellent example of this resource is their review and recommendations on ECTRs for poisoning secondary to beta-adrenergic antagonists (BAAs).

Evidence

The EXTRIP workgroup included 76 publications in this comprehensive review on the use of ECTRs in BAA poisoning [2]. They evaluated pharmacokinetic/toxicokinetic data for a total of 334 patients poisoned with various BAAs, of which ~90% of the data was published prior to 1990 and does not necessarily represent the improved clearance of these medications with modern ECTR modalities. Based on this evidence, they deemed atenolol, nadolol, and sotalol as dialyzable BAAs. They also reviewed case reports/series of 37 patients with BAA toxicity and made recommendations for those agents with sufficient evidence. Based on the above data, the EXTRIP group recommends iHD over CRRT in patients severely poisoned with atenolol or sotalol and kidney impairment. They make no recommendation for or against ECTR in patients severely poisoned with atenolol or sotalol with normal kidney function and they recommend against ECTR in patients severely poisoned with propranolol.

 Bottom Line

  • Some toxic ingestions may require invasive treatment strategies (e.g., ECTRs) but a comprehensive review of the literature may not be possible
  • The EXTRIP website is an excellent resource to assess if patients should receive emergent ECTRs due to specific toxins
  • Hemodialysis is recommended in severely symptomatic patients poisoned with atenolol or sotalol and with impaired kidney function

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. Ghannoum M, Nolin TD, Lavergne V, Hoffman RS, EXTRIP workgroup. Blood purification in toxicology: nephrology’s ugly duckling. Adv Chronic Kidney Dis. 2011;18(3):160-166. doi: 10.1053/j.ackd.2011.01.008. PMID: 21531321.
  2. Bouchard J, Shepherd G, Hoffman RS, et al. Extracorporeal treatment for poisoning to beta-adrenergic antagonists: systematic review and recommendations from the EXTRIP workgroup. Crit Care. 2021;25(1):201. doi: 10.1186/s13054-021-03585-7. PMID: 34112223.

Oral Antivirals for Treatment of Mild-Moderate COVID-19 Infection

Background

Two new oral agents were given Emergency Use Authorization to be used in patients with mild-moderate COVID-19 at high risk of progression to severe infection, molnupiravir and nirmatrelvir/ritonavir (Paxlovid) [1,2]. Prior to this authorization, most evidence-based COVID therapies were parenteral and required significant healthcare resources to coordinate and administer.

Comparison

Nirmatrelvir/ritonavir [3]Molnupiravir [4]
Mechanism

Protease inhibitor leadings to interruption of viral replication

Ritonavir has no role in treating COVID-19, it is only included to boost levels of nirmatrelvir via CYP3A4 inhibition

Increased frequency of RNA mutations and impaired replication [5]
Efficacy vs Placebo (Hospitalization or Death)0.8% vs 6.3% (CI -7.21 to -4.03)6.8% vs 9.7% (CI -5.9 to -0.1)
Drug InteractionsCYP3A4 inducers, inhibitors, and substrates

May decrease efficacy of hormonal contraceptives, non-hormonal contraceptives should be considered

Contraindicated medications include: amiodarone, carbamazepine, clozapine, colchicine, dihydroergotamine, dronedarone, flecainide, lovastatin, ranolazine, sildenafil, simvastatin

Many other important interactions exist so care should be taken to assess all medication interactions

N/A
Cost*Patient: $0

US government: $530 [6]

Patient: $0

US Government: $700 [7]

Dose300 mg/100 mg BID for 5 days

Must be started within 5 days of symptom onset

800 mg BID for 5 days

Must be started within 5 days of symptom onset

NotesApproved for patients ≥ 12 years old AND ≥ 40 kg

Not approved for inpatient initiation

If patient is hospitalized, continuation is up to the discretion of the provider

Not used as pre-/post-exposure prophylaxis

Approved for patients ≥ 18 years

Not approved for inpatient initiation

If patient is hospitalized, continuation is up to the discretion of the provider

Not used as pre-/post-exposure prophylaxis

Renal/Hepatic Dose AdjustmentseGFR  ≥30 to <60 mL/min: 150 mg/100 mg BID

eGFR <30 mL/min: Not recommended

Child-Pugh class C: Not recommended

None

*Note: The US federal government has purchased 10 million doses of nirmatrelvir/ritonavir and 3 million doses of molnupiravir [8,9]. These supplies will be allocated to states and territories as needed and will be available to patients at no charge. 

Evidence:

Nirmatrelvir/ritonavir (Paxlovid)

Paxlovid was evaluated in the EPIC-HR trial, which is not fully published at this time [3]. This was a phase 2/3, double-blinded, randomized placebo controlled trial including nonhospitalized, unvaccinated patients adults with mild-moderate COVID-19 within 5 days of symptom onset with at least 1 risk factor for development of severe illness from COVID-19. Exclusion criteria included patients with a history of COVID-19 infection or COVID vaccination. Patients were given Paxlovid 300 mg/100 mg or placebo BID for 5 days. The primary outcome was hospitalization or death at day 28. The modified intention-to-treat1 (mITT1) group excluded patients who did not receive nor were expected to receive COVID-19 mAb treatment. In the mITT1 group, the primary outcome occurred in 0.8% of patients receiving Paxlovid vs 6.3% of patients in the placebo group (8/1039 vs 66/1046, CI -7.21 to -4.03).

These results appear quite robust with a fragility index of 37. Additionally, in patients with detectable COVID antibodies there was less of an impact of the study medication. However, these patients still appeared to have some benefit (0.2% vs 1.5%, CI -2.45 to -0.23) which suggests that vaccinated patients may still benefit from Paxlovid.

Risk factors for progression to severe disease: BMI >25, chronic lung disease, asthma, chronic kidney disease, current smoker, immunosuppressive disease or immunosuppressive treatment, cardiovascular disease, hypertension, sickle cell disease, neurodevelopmental disorders, active cancer, medically-related technological dependence, or age >60 years

Molnupiravir 

Molnupiravir was evaluated in the MOVe-OUT trial [10]. This was a phase 3, double-blinded, randomized, placebo controlled trial including nonhospitalized, unvaccinated adults with mild-moderate COVID-19 within 5 days of symptom onset with at least 1 risk factor for development of severe illness from COVID-19. Exclusion criteria included anticipated hospitalization within 48 hours, eGFR <30 or dialysis dependent, pregnancy, and COVID vaccination. Patients were able to receive steroids but not monoclonal antibodies (mAbs) nor remdesivir. Patients were given molnupiravir 800 mg or placebo BID for 5 days. The primary outcome was hospitalization or death at 29 days. In the mITT population, the primary outcome occurred in 6.8% of patients in the study group vs 9.7% in the placebo group (48/709 vs 68/699, CI -5.9 to -0.1). Death occurred in 1 patient on molnupiravir and in 9 patients on placebo (0.1% vs 1.3%, RRR 89%, CI 14 to 99).

Despite the above results, this may not be the positive trial it initially appears. First of all, for the primary outcome, the fragility index is 0, meaning that if 1 more patient in the study group experienced the primary outcome then it would have changed the statistical significance. Additionally, when the mITT analysis was adjusted for sex, the absolute risk reduction remained 2.8% but the confidence interval was not significant (-5.7 to 0.1). Lastly, in the subgroup analysis, there was no benefit in patients that had positive COVID antibody tests and there was a slight preference towards placebo over molnupiravir (3.7% vs 1.4%, ARR 2.3, CI -1.7 to 7.1). This suggests that vaccinated patients may not benefit from this therapy as much (or at all) as compared to unvaccinated patients.

Risk factors for progression to severe disease: age >60 years, active cancer, chronic kidney disease, COPD, BMI ≥30, heart failure, coronary artery disease, cardiomyopathy, or diabetes mellitus

Note: Both the EPIC-HR and MOVe-OUT studies were funded by their respective pharmaceutical company.

Bottom Line:

  • Nirmatrelvir/ritonavir (Paxlovid) and molnupiravir are approved under FDA EUAs for patients with mild-moderate COVID infection at high risk of severe disease within 5 days of symptom onset
  • Both medications appear to reduce death or hospitalization within a month, with most benefit likely to be experienced by unvaccinated patients
  • Nirmatrelvir/ritonavir (Paxlovid) appears to be more effective but also has many more drug interactions and contraindications

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. O’Shaughenessy J. Food and Drug Administration. Molnupiravir Emergency Use Authorization 108. December 23, 2021. https://www.fda.gov/media/155053/download
  2. O’Shaughenessy J. Food and Drug Administration. Nirmatrelvir/ritonavir Emergency Use Authorization 105. December 22, 2021. https://www.fda.gov/media/155049/download
  3. Nirmatrelvir/ritonavir. Package insert. Pfizer, Inc. 2021. https://www.fda.gov/media/155050/download
  4. Molnupiravir. Package insert. Merck Sharp & Dohme Corp. 2021. https://www.merck.com/eua/molnupiravir-hcp-fact-sheet.pdf
  5. Kabinger F, Stiller C, Schmitzová J, et al. Mechanism of molnupiravir-induced SARS-CoV-2 mutagenesis. Nat Struct Mol Biol. 2021;28(9):740-746. doi: 10.1038/s41594-021-00651-0. PMID: 34381216.
  6. Mishra M. U.S. to buy 10 mln courses of Pfizer’s COVID-19 pill for $5.3 bln. Reuters. Accessed January 12, 2022. https://www.reuters.com/business/healthcare-pharmaceuticals/us-govt-buy-10-mln-courses-pfizers-covid-19-pill-529-bln-2021-11-18/
  7. Willyard C. How antiviral pill molnupiravir shot ahead in the COVID drug hunt. Nature. Published online October 8, 2021. doi: 10.1038/d41586-021-02783-1. PMID: 34625735.
  8. Paxlovid (nirmatrelvir/PF-07321332 and ritonavir). U.S. Department of Health & Human Services: Office of the Assistant Secretary of Preparedness and Response. Updated: January 12, 2022. Accessed January 12, 2022. https://www.phe.gov/emergency/events/COVID19/investigation-MCM/Paxlovid/Pages/default.aspx
  9. Molnupiravir (MK-4482). U.S. Department of Health & Human Services: Office of the Assistant Secretary of Preparedness and Response. Updated: January 12, 2022. Accessed January 12, 2022. https://www.phe.gov/emergency/events/COVID19/investigation-MCM/molnupiravir/Pages/default.aspx
  10. Jayk Bernal A, Gomes da Silva MM, Musungaie DB, et al. Molnupiravir for oral treatment of covid-19 in nonhospitalized patients. N Engl J Med. Published online December 16, 2021. doi: 10.1056/NEJMoa2116044. PMID: 34914868.

Balanced Fluids in Diabetic Ketoacidosis

Background

Many guidelines and treatment algorithms for diabetic ketoacidosis (DKA) recommend sodium chloride 0.9% as the replacement fluid of choice, though alternative fluids may be a better option [1-4]. Randomized trials, in adult and pediatric patients, demonstrate faster resolution of DKA when using balanced solutions (e.g.PlasmaLyte-A, lactated Ringer’s) compared to sodium chloride [5-7]. Dr. Josh Farkas provides further review of this topic in 3 excellent and detailed EMCrit posts [8-10].

Evidence

A phase-2 study published in 2021, SCOPE-DKA, randomized 93 patients with severe DKA (median venous pH 7.0) to receive PlasmaLyte-148 (PlasmaLyte-A) or sodium chloride 0.9% [11]. During the first 48 hours of treatment, patients received a average of ~6.5 L of fluid. At 24-hours, more patients in the PlasmaLyte group had resolution of DKA (defined as base excess ≥ -3 mEq/L) as compared to the sodium chloride group (69% vs 36%, p=0.002). However, by 48-hours, both groups had similar rates of DKA resolution (96% vs 86%, p=0.111). The study authors concluded that PlasmaLyte-148 may lead to faster resolution of metabolic acidosis in patients with DKA without an increase in ketosis, in line with findings from previous studies, but these results need to be confirmed in a larger, Phase 3 trial.

To further explore the nuances, strengths, and weaknesses of this study, please read the REBEL EM review by Dr. Mark Ramzy [13].

Bottom Line

  • The available data suggests that balanced fluids are beneficial in mild, moderate, and severe DKA.
  • PlasmaLyte-148 (PlasemaLyte A) may lead to faster resolution of metabolic acidosis than sodium chloride 0.9%. Though these findings need confirmation in a large, Phase 3 trial.
  • Generally, the composition of the initial liter is less important than prompt administration. However, for subsequent liters, a balance crystalloid (e.g., PlasmaLyte-148, or lactated Ringer’s) should be used instead of sodium chloride 0.9%.

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. Wolfsdorf J, Glaser N, Sperling MA, American Diabetes Association. Diabetic ketoacidosis in infants, children, and adolescents: A consensus statement from the American Diabetes Association. Diabetes Care. 2006;29(5):1150-1159. PMID: 16644656. doi: 10.2337/diacare.2951150.
  2. Kitabchi AE, Umpierrez GE, Miles JM, Fisher JN. Hyperglycemic crises in adult patients with diabetes. Diabetes Care. 2009;32(7):1335-1343. PMID: 19564476. doi: 10.2337/dc09-9032.
  3. Canadian Diabetes Association Clinical Practice Guidelines Expert Committee, Goguen J, Gilbert J. Hyperglycemic emergencies in adults. Can J Diabetes. 2013;37 Suppl 1:S72-76. PMID: 24070967. doi: 10.1016/j.jcjd.2013.01.023.
  4. Joint British Diabetes Societies Inpatient Care Group. The Management of Diabetic Ketoacidosis in Adults. 2021; online publication. Accessed January 3, 2022. https://abcd.care/sites/abcd.care/files/site_uploads/JBDS_02%20_DKA_Guideline_amended_v2_June_2021.pdf.
  5. Mahler SA, Conrad SA, Wang H, Arnold TC. Resuscitation with balanced electrolyte solution prevents hyperchloremic metabolic acidosis in patients with diabetic ketoacidosis. Am J Emerg Med. 2011;29(6):670-674. PMID: 20825879. doi: 10.1016/j.ajem.2010.02.004.
  6. Williams V, Jayashree M, Nallasamy K, Dayal D, Rawat A. 0.9% saline versus Plasma-Lyte as initial fluid in children with diabetic ketoacidosis (SPinK trial): a double-blind randomized controlled trial. Crit Care. 2020;24(1):1. PMID: 31898531. doi: 10.1186/s13054-019-2683-3.
  7. Self WH, Evans CS, Jenkins CA, et al. Clinical effects of balanced crystalloids vs saline in adults with diabetic ketoacidosis: a subgroup analysis of cluster randomized clinical trials. JAMA Netw Open. 2020;3(11):e2024596. PMID: 33196806. doi: 10.1001/jamanetworkopen.2020.24596.
  8. Farkas J. Four DKA Pearls. 2014. Accessed January 3, 2022. https://emcrit.org/pulmcrit/four-dka-pearls.
  9. Farkas J. Dominating the acidosis in DKA. 2016. Accessed January 3, 2022. https://emcrit.org/pulmcrit/bicarbonate-dka.
  10. Farkas J. IBCC – Diabetic Ketoacidosis (DKA). 2021. Accessed January 3, 2022. https://emcrit.org/ibcc/dka.
  11. Ramanan M, Attokaran A, Murray L, et al. Sodium chloride or Plasmalyte-148 evaluation in severe diabetic ketoacidosis (Scope-dka): a cluster, crossover, randomized, controlled trial. Intensive Care Med. 2021;47(11):1248-1257. PMID: 34609547. doi: 10.1007/s00134-021-06480-5.
  12. Ramzy M. SCOPE-DKA: Normal Saline vs Plasmalyte in Severe DKA. 2021. Accessed January 3, 2022. https://rebelem.com/scope-dka-normal-saline-vs-plasmalyte-in-severe-dka.

Dose Order Matter? Which Antibiotic to Give First for a Bloodstream Infection

Background

Early antibiotics are recommended for treatment of many infections, including patients with sepsis or septic shock [1]. Critically-ill patients and those with a suspected infection at risk for severe illness are generally administered two (or more) empiric antibiotics in the emergency department (ED) which cover a wide range of potential pathogens. A typical approach includes utilizing a broad-spectrum antibiotic (frequently a beta-lactam such as cefepime or piperacillin-tazobactam) plus an anti-MRSA agent (typically vancomycin).

Early in the patient’s hospital stay they may have limited IV access, so the question often arises as to which antibiotic to give first, the broad-spectrum antimicrobial or the anti-MRSA agent. Additionally, though the overall risk of an allergic reaction is relatively low with most antimicrobials, when multiple agents are given simultaneously it can be difficult to ascertain which one may have caused a reaction and lead to incorrectly documented allergies, so it can be important to consider if the initial doses should be administered separately. However, there isn’t strong data to guide practice in terms of giving the initial antibiotics concurrently vs consecutively, from an allergy perspective. To further complicate the issue, patients may also develop delayed reactions so a strong causal relationship cannot always be determined. In practice, there are times (increasingly so with rising ED patient volumes) when we give antibiotics one at a time simply for logistical reasons. So that begs the question, which antibiotic should be given first?

Evidence

In patients with sepsis or septic shock, early antibiotics significantly decrease mortality [1]. This relationship is strongest for patients with septic shock, where the odds of in-hospital mortality was increased by 1.04-1.16 for each hour antibiotics were delayed [2-4]. Notably, broad spectrum antibiotics are deemed such as they cover both gram positive and gram negative pathogens, therefore the addition of an anti-MRSA agent contributes a relatively smaller amount of coverage and is primarily targeted at resistant gram-positive bacteria. Additionally, gram-negative pathogens tend to cause a higher degree of illness and mortality, so it would be reasonable to give the broad-spectrum antibiotic first [5-7]. As both cefepime and piperacillin-tazobactam are recommended to be infused over 30 minutes (though this can vary based on institutional policies) and vancomycin is typically infused over 1 hour for each gram, if vancomycin is administered first, patients may wait hours to receive a broad spectrum agent.

A recent study now supports this practice. This is an observational trial which evaluated 3,376 patients with a blood stream infection, 2,685 patients received a beta-lactam first and 691 patients received vancomycin first [8]. They found that patients who received a beta-lactam prior to vancomycin had significantly improved 48-hour and 7-day mortality. Further review of this article may be found on the JournalFeed blog post.

Bonus tip: Having antibiotics stocked on the unit reduces time to administration [9].

Bottom Line

  • Antibiotic delays lead to increased mortality, especially in patients with septic shock.
  • For patients with a suspected bloodstream infection, administering the broad-spectrum antibiotic first, instead of the anti-MRSA agent, has the potential to reduce mortality at 48 hours and 7 days. This should be the general approach for treatment of all infections when two or more antimicrobial agents are indicated.

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. Evans L, Rhodes A, Alhazzani W, et al. Surviving sepsis campaign: international guidelines for management of sepsis and septic shock 2021. Crit Care Med. 2021;49(11):e1063-e1143. PMID: 34605781. doi: 10.1097/CCM.0000000000005337.
  2. Seymour CW, Gesten F, Prescott HC, et al. Time to treatment and mortality during mandated emergency care for sepsis. N Engl J Med. 2017;376(23):2235-2244. PMID: 28528569. doi: 10.1056/NEJMoa1703058.
  3. Liu VX, Fielding-Singh V, Greene JD, et al. The timing of early antibiotics and hospital mortality in sepsis. Am J Respir Crit Care Med. 2017;196(7):856-863. PMID: 28345952. doi: 10.1164/rccm.201609-1848OC.
  4. Peltan ID, Brown SM, Bledsoe JR, et al. Ed door-to-antibiotic time and long-term mortality in sepsis. Chest. 2019;155(5):938-946. PMID: 30779916. doi: 10.1016/j.chest.2019.02.008.
  5. Abe R, Oda S, Sadahiro T, et al. Gram-negative bacteremia induces greater magnitude of inflammatory response than Gram-positive bacteremia. Crit Care. 2010;14(2):R27. PMID: 20202204. doi: 10.1186/cc8898.
  6. Alexandraki I, Palacio C. Gram-negative versus Gram-positive bacteremia: what is more alarmin(G)? Crit Care. 2010;14(3):161. PMID: 20550728. doi: 10.1186/cc9013
  7. Morgan MP, Szakmany T, Power SG, et al. Sepsis patients with first and second-hit infections show different outcomes depending on the causative organism. Front Microbiol. 2016;7:207. PMID: 26955367. doi: 10.3389/fmicb.2016.00207.
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