US Journal Club February, 2020: Ultrasound in Hypotension

Paper #1:

Does Point-of-Care Ultrasonography Improve Clinical Outcomes in Emergency Department Patients With Undifferentiated Hypotension? An International Randomized Controlled Trial From the SHoC-ED Investigators

Atkinson, P et al. Annals of Emergency Medicine; 72: 478 – 489. https://doi.org/10.1016/j.annemergmed.2018.04.002 

Full text: https://www.annemergmed.com/article/S0196-0644(18)30325-1/fulltext 

  • Introduction and background information 
    • Patients presenting to the ED with hypotension require a high level of care and resource intensive resuscitations. A 2004 study from Annals of Emergency Medicine examined more than 7,000 non-trauma patients with out-of-hospital hypotension and found that mortality was 32% for the hypotensive group compared to 11% for the non-hypotensive group.1 
    • POCUS has been studied extensively in shock. In 2015 examiners evaluated 118 patients and found that early ultrasound use in hypotension reduced diagnostic uncertainty.2 
    • The Rapid Ultrasound in SHock (RUSH) protocol has been demonstrated to accurately identify critical diagnoses.3-5 However, the authors note that to date there is little evidence to show “added patient-oriented outcome[s]”, such as survival, using these protocols.
  • What was the primary objective of this study?
    • Provide a clear understanding of how the use of POCUS directly affects clinically important patient outcomes for patients with hypotension. 
  • Methods and study design
    • International, multicenter, randomized control trial with enrollment by convenience sample
    • 3 centers in North America and 3 in South Africa 
    • All ultrasounds were performed by either residents with supervision or ultrasound “competent” attendings
    • Protocol was a combination of the ACES and RUSH protocol
    • Inclusion:
      • Patients > 19 years
      • SBP < 100 or a shock index > 1 (HR/SBP) with SBP < 120
    • Exclusion:
      • Pregnancy
      • Need for CPR, defibrillation or pacing
      • Trauma 
      • MI
      • “Clear cause” for hypotension identified immediately
      • Previous diagnosis from outside hospital
      • A vagal episode
      • “Known” non pathologic low BP
    • Randomly assigned to control (standard care) or intervention (POCUS)
    • Initial and secondary diagnoses were recorded at 0 and 60 minutes
  • What was the primary outcome of the study?
    • Survival to 30 days or hospital discharge. Secondary outcomes included initial treatment (pressors or fluids), rates of CT use, admission rates and total length of stay 
  • Results
    • 273 patients were enrolled over 4 years
    • Median SBP 91 and median pulse 109
    • 87% of cases of hypotension were due to non-cardiogenic shock, sepsis being the most common (52%)
    • No significant difference noted in 30 day survival or hospital discharge
  • Discussion
    • Authors found no important benefit with the addition of POCUS to the primary outcome
    • They propose that abnormal findings are common on ultrasound, but these are equally detectable with methods like CT
    • Also propose that clinicians may already be adept at managing hypotension with or without ultrasound
  • Were there any limitations?
    • Study was powered for an n = 400, mortality of 30% and 10% mortality reduction, none of which were achieved. Therefore, conclusions have low confidence
    • Most common finding was septic shock, which has no specific finding on ultrasound
    • Large amount of exclusion criteria which may have missed patients who would have shown a benefit 
    • How often was someone excluded for “clear cause” of hypotension? How was it decided what a “clear” cause was?
  • Take home points
    • The authors examined mortality outcomes with the use of ultrasound versus “standard” care in non-trauma hypotensive patients and concluded that no difference exists
    • There are multiple concerns with the study design including low total enrollment and 10% expected reduction in mortality leading to significant underpowering
    • Most of the patients had sepsis as a cause of their hypotension (as expected), which does not have findings on ultrasound, so benefit would not be shown
    • Many patients were excluded who likely would have benefited from ultrasound and altered outcomes

References

  1. Jones, Alan E et al. Nontraumatic out-of-hospital hypotension predicts inhospital mortality. Annals of Emergency Medicine, Volume 43, Issue 1, 106 – 113. https://doi.org/10.1016/j.annemergmed.2003.08.008
  1. Shokoohi, Hamid et al. Bedside Ultrasound Reduces Diagnostic Uncertainty and Guides Resuscitation in Patients With Undifferentiated Hypotension. Critical Care Medicine: December 2015 – Volume 43 – Issue 12 – p 2562-2569.
  1. Phillips, P et al. The RUSH Exam: Rapid Ultrasound in SHock in the Evaluation of the Critically lll. Emergency Medicine Clinics of North America, Volume 28, Issue 1, 2010, Pages 29-56. https://doi.org/10.1016/j.emc.2009.09.010.
  1. Ghane, M et al. Accuracy of early rapid ultrasound in shock (RUSH) examination performed by emergency physician for diagnosis of shock etiology in critically ill patients. J Emerg Trauma Shock. 2015 Jan-Mar;8(1):5-10. doi: 10.4103/0974-2700.145406.
  1. Bagheri-Hariri, S., Yekesadat, M., Farahmand, S. et al. The impact of using RUSH protocol for diagnosing the type of unknown shock in the emergency department. Emerg Radiol 22, 517–520 (2015). https://doi.org/10.1007/s10140-015-1311-z

Paper #2:

Randomized, controlled trial of immediate versus delayed goal-directed ultrasound to identify the cause of nontraumatic hypotension in emergency department patients

Jones, A et al. Crit Care Med. 2004 Aug;32(8):1703-8. doi:10.1097/01.CCM.0000133017.34137.82

Full text: https://journals.lww.com/ccmjournal/Abstract/2004/08000/Randomized,_controlled_trial_of_immediate_versus.11.aspx

  • Introduction and background information 
    • Ultrasound has become an increasingly utilized diagnostic modality for patients with undifferentiated hypotension presenting to the emergency department.
    • However, the authors note that “the diagnostic utility of ultrasound in patients with nontraumatic, undifferentiated hypotension has not been systematically evaluated.” 
  • What was the primary objective of this study?
    • The results of a goal-directed ultrasound protocol would significantly narrow the number of potential viable diagnoses of patients with nontraumatic, symptomatic, undifferentiated hypotension and would improve accuracy in identifying correct diagnosis.
  • Methods and study design
    • Randomized controlled trial from 2002 to 2003 at single center
    • Patients randomized to immediate or delayed goal directed ultrasound
    • Designated an initial differential diagnosis followed by a second, revised diagnosis
    • US performed by 3rd year EM resident or EM attending
    • 7 views total, similar to a RUSH exam
    • All residents had 1 month US rotation and attendings were US credentialed
    • Inclusion criteria
      • Age > 17 years
      • SBP < 100 or SI > 1.0
      • At least one sign or symptom of shock (see table 1 of study)
    • Exclusion criteria
      • History of “low blood pressure”
      • CPR/defibrillation/ACLS
      • Trauma
      • MI
      • “Obvious” cause of shock 
  • Results
    • 202 patients enrolled with final sample size of 184
    • Average time to complete US was 5.8 minutes
    • At 15 mins, the correct diagnosis was found in 80% of immediate ultrasound group vs 50% in delayed ultrasound group
    • At 30 minute time point there was significant decrease in potential diagnosis in immediate ultrasound group
    • Most common diagnoses were septic shock (43%) and dehydration (28%)
    • No significant difference with in-hospital mortality
  • Discussion
    • The first study to demonstrate that goal-directed ultrasound can positively affect the differential diagnosis for undifferentiated shock
    • Data shows a “window of opportunity” for physicians to intervene early in these patients
  • Were there any limitations?
    • Did not measure any patient oriented outcomes 
    • No classic control group (with no ultrasound)
    • Residents enrolled patients and due to potential lack of clinical confidence may have included more differential diagnoses
  • Take home points
    • The authors examined immediate vs delayed ultrasound in undifferentiated, symptomatic hypotension
    • Found significant decrease in viable diagnostic etiologies in group with immediate goal-directed ultrasound
    • Future studies could examine patient oriented outcomes

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