UMEM Educational Pearls

Diastolic Blood Pressure

• The diastolic blood pressure (DBP) is determined by vascular tone and remains relativley constant throughout the arterial system.
• A low DBP (< 50 mm Hg) suggests vasodilation and may be associated with an increased risk of myocardial ischemia and left ventricular dysfunction.
• In a recent trial, Ospina-Tascon and colleagues described the diastolic shock index (heart rate/DBP) and found that a DSI > 2.2 was associated with higher mortality in patients with septic shock.
• Take Home Point: pay attention to the DBP and, when low, consider initiation of vasopressors concomitant with fluid resuscitation.

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• TXA has been used for pediatric non-traumatic (surgical) bleeding with good evidence
• Currently used in around 1/3 of pediatric trauma centers based on survey data
• PED-TRAX (retrospective review of pediatric trauma admissions in a combat zone) showed an association between use of TXA and decreased mortality, with no increase in thromboembolic events
• Dosing strategies in the literature and in practice have been variable (bolus at variable dosing versus bolus + infusion)
• The TIC TOC trial was recently completed - a multicenter randomized pilot study looking at 2 dosing strategies of TXA versus placebo which demonstrated feasibility of a larger study and will hopefully serve as a model for further research to determine efficacy as well as ideal dosing

Bottom line: There is not clear evidence for efficacy, but trends are positive and the documented rates of adverse effects in this population are low. It is reasonable to give, especially in patients requiring massive transfusion or who are critically ill.

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Hemodynamic instability and cardiac arrest are major complications following endotracheal intubation.  The mantra “resuscitate before you intubate” has prompted several studies of how to prevent this.

The PREPARE II trial is a multicenter ICU-based trial studying the effect of 500cc of crystalloid versus no crystalloid pre-emptively to prevent hypotension following endotracheal intubation. The study enrolled 1067 critically ill patients in United States ICUs. Some 60% of patient were intubated for respiratory failure and 20% were already on vasopressor.  The primary induction drugs we etomidate and rocuronium. Importantly, urgent intubation was an exclusion. There were no differences in multiple endpoints including hypotension, new need for vasopressors, cardiac arrest, or 28-day mortality. 

This was in some ways this in not unexpected and patients already in an ICU setting have typically received some form of fluid loading already. Being ICU based and primarily a more smoldering medical population this has limited application to more emergent and undifferentiated settings, but study underscores the need for a broad and nuanced view of what “resuscitate” means. Positive pressure may exacerbate hypovolemia, but the patient’s underlying disease, the effect of anesthetic drugs both by direct action via relief of pain, discomfort, or dyspnea may predominate if you think the patient is euvolemic.

Remember to dose anesthetics/sedatives/RSI drugs with an eye toward hemodynamics and consider starting vasopressors prior to intubation

Bottom Line:

-In a broad well-conducted ICU-based study a 500cc peri-intubation bolus doesn’t prevent hypotension

-Have a broad view of what resuscitation for intubation might entail

-Having fluid ready for intubation is helpful, hemodynamic dosing of drugs and having a plan for vasopressors might be even more helpful

-Applicability to ED environments is limited in this ICU-based trial

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Have you ever wonder what patients feel after being intubated in the ED?

The study " Awareness With Paralysis Among Critically Ill Emergency Department Patients: A Prospective Cohort Study" aimed at answering just that.

Settings: Emergency Departments from 3 hospitals; This was a secondary analysis of a prospective trial.

Patients:

Patients who received neuromuscular blockade in ED

Intervention: None.

Comparison: None.

Outcome: Primary outcome was Awareness while paralyzed, secondary outcome was Perceived threat, which is considered the pathway for PTSD.

Study Results:

The study evaluated 388 patients.  There were 230 (59%) patients who received rocuronium.

Patients who received rocuronium (5.5%, 12/230) were more likely to experience awareness than patients receiving other neuromuscular blockade (0.6%, 1/158).

Patients who experienced awareness during paralysis had a higher threat perception score that those who did not have awareness (15.6 [5.8] vs. 7.7 [6.0], P<0.01).

A multivariable logistic regression, after adjustment for small sample size, showed that Rocuronium in the ED was significantly associated with awareness (OR 7.2 [1.39-37.58], P = 0.02). 

Discussion:

With the increasing use of rocuronium for rapid sequence intubation in the ED, clinicians should start to pay more attention to the prevalence of awareness during paralysis.  According to the study, patients reported pain from procedures, being restrained, and worst of all feelings of impending death.

One of the risk factors for awareness during paralysis would be the long half-life of rocuronium, compared to that of succinylcholine.  Therefore, clinicians should consider prompt and appropriate dosage of sedatives for post-intubation sedation.  Previous studies showed that a mean time from intubation till sedatives was 27 minutes (2), and propofol was started at a low dose of 30 mcg/kg/min for ED intubation (3). 

Conclusion:

Approximately 5.5% of all patients or 4% of survivors of patients who had invasive mechanical ventilation in the ED experienced awareness during paralysis.  They also were at high risk for PTSD.

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Question

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Tachyarrhythmias in the setting of high-dose vasopressors due to septic shock are not uncommon. Aside from amiodarone, some providers may not know of alternative therapeutic options in the setting of septic shock. In addition, some may view the use of a beta-blocker as counter-intuitive or counter-productive in the setting of norepinephrine usage.

However, there have been multiple smaller studies evaluating using esmolol (and other short-acting beta-blockers) in the setting of tachycardia, septic shock and pressors. Outcomes regarding the theoretical benefits of beta-blockade in sepsis (i.e. decreased mortality/morbidity 2/2 decreased sympathetic innervation, inflammation, myocardial demand etc.) have been varied. However, esmolol has been demonstrated multiple times to be effective at reducing heart rate without significant adverse outcomes (i.e. no sig diff in mortality, refractory shock, or time on vasopressors).  

Caveats/pitfalls

-most of the studies discuss “adequate resuscitation” prior to initiation of esmolol

-not studied in patients that also had significant cardiac dysfunction 

-be aware that esmolol gtts can be a lot of volume and pts can become volume overloaded if boarding in the ED for an extended period of time

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Balanced crystalloids:  So Hot Right Now

Brief Read:

The use of balanced crystalloids has been the subject of several RCTs with conflicting results. However, recent post-hoc and meta-analyses of these same trials suggest that balanced crystalloids may be the best choice initially. See nice summary at: https://www.atsjournals.org/doi/full/10.1164/rccm.202203-0611ED.

Long Read:

While I had thought about summarizing the recently published data on EPR from the CRITICAL trial in Japan, JournalFeed today covered the recent post-hoc analysis of the BaSICS trial originally seen on CC Pearls back in August 31, 2021 by Dr. Sjelocha. This subject is as important as it is confusing. There are large and relatively well done RCTs that point in opposite and sometimes strange directions. However, as the authors of the SMART trial summarized, even an NNT of 94 in this population could be a huge number of patients!

The use of balanced crystalloids (e.g. Plasmalyte) has been the subject of several previous RCTs (SMART and SALT-ED) with conflicting results. Recently the PLUS RCT and BaSICS trials seemed to push the literature towards to concluding there was no difference, but there are caveats for both trials now in the literature:

• While the PLUS RCT found no difference, a concurrently published meta-analysis seemed to conclude the opposite (https://doi.org/10.1056/EVIDoa2100010).
• Further confusing the issue, apost-hoc analysis of the similarly negative BaSICS RCTcame out in March 2022 suggesting that overall there was a benefit for patients who received balanced crystalloid when they hit the door, but that those who arrived with sepsis and were unplanned admissions benefited most!
  • The authors note that their original analysis is likely affected by the fact that 68% of the original BaSICS study population had already received balanced fluid, saline, or both before randomization.

This paper makes a nice point which I think is important for us in the ED: the evidence is suggesting a commonality in many critical care concepts, which is that decisions made in early resuscitation may have an outsized impact on patient outcomes. However, this will not be the last we hear on this subject, but for the time being, I agree with Dr. Lacy that “It might not matter as much what fluids you choose when patients are on their third, fourth, or fifth liter of fluid – but especially for the sickest patients, it sure seems like the initial resuscitation fluid makes a difference.”

BaSICS post hoc: https://www.atsjournals.org/doi/full/10.1164/rccm.202111-2484OC (See JournalFeed post from today and the accompanying editorial)

• 68% (10,520) of enrolled patients had balanced crystalloids (3,202), saline (2,096), or both (1,862) prior to enrollment
• “There was a high probability that balanced solution use was associated with lower 90-day mortality in patients who exclusively received balanced solutions before study enrollment.”

BASICS: https://jamanetwork.com/journals/jama/fullarticle/2783039 (summary stolen from Dr. Sjeklocha’s  August 31, 2022 CC Pearl)

• No difference in 90 days mortality (P-Lyte 26.4% v NS 27.2, aHR p=0.47), AKI or RRT out to 7-days, or in duration of MV, ICU LOS or hospital LOS
• Signal for possible harm in TBI population with balanced crystalloids compared to normal saline

PLUS: https://www.nejm.org/doi/10.1056/NEJMoa2114464

• 5,037 critically ill patients
• No statistically significant difference in the primary outcome of death within 90 days of randomization in the BMES group compared to the saline group (21.8% vs 22.0%, 95% CI -3.6 to 3.3; P=0.90).
• Subgroup analyses were conducted based on illness severity before randomization, presence of sepsis, kidney injury, age, sex, and ICU admission after surgery, and did not show a significant difference between the two groups.

SMART: https://www.nejm.org/doi/full/10.1056/nejmoa1711584

• 7942 patients in the balanced-crystalloids group,
• Balanced: 1139 (14.3%) versus Saline: 1211 of 7860 patients (15.4%) had a major adverse kidney event in the saline group (marginal odds ratio, 0.91; 95% confidence interval [CI], 0.84 to 0.99; conditional odds ratio, 0.90; 95% CI, 0.82 to 0.99; P=0.04).
• “Our results suggest that the use of balanced crystalloids rather than saline might prevent 1 patient among every 94 patients admitted to an ICU from the need for new renal-replacement therapy, from persistent renal dysfunction, or from death.”

SALT-ED: https://www.nejm.org/doi/full/10.1056/nejmoa1711586

• 13,347 patients
• The number of hospital-free days did not differ between the balanced-crystalloids and saline groups (median, 25 days in each group; adj. OR, 0.98; 95% CI, 0.92 to 1.04; P=0.41).
• Balanced crystalloids resulted in a lower incidence of major adverse kidney events within 30 days than saline (4.7% vs. 5.6%; adjusted odds ratio, 0.82; 95% CI, 0.70 to 0.95; P=0.01).

https://journalfeed.org/article-a-day/2022/back-to-basics-first-fluid-choice-matters-a-reanalysis-of-the-basics-rct/

Question

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Prior studies have found that patients are at an increased risk for hypoglycemia when administered insulin for the acute management of hyperkalemia when they have renal dysfunction.  A new single-center, retrospective study investigated the risk of hypoglycemia and the overall effect of potassium lowering in patients with renal dysfunction and stratified outcomes based on the CKD level.

Patients were included if they were ordered insulin for hyperkalemia using a hospital driven order set and had CKD stages 3a, 3b, and 4.  They were excluded if they had dialysis within 6h of insulin administration, had DKA, or no repeat labs.  The hospital order set encourages 5 units of insulin instead of 10 when “renal failure” is present without clear guidance.

377 patients were included: 186 received 5 units and 191 received 10 units.  The average age was 65 years old, predominantly male, weighing 90 kg.  In the 5 unit group, significantly more patients had CKD stage 4 (60% v 30%) and in the 10 unit group, significantly more patients were CKD stage 3a (p<0.001).  The baseline serum potassium was 6 in each group.

The hypoglycemia incidence was not different between groups, with severe hypoglycemia occurring twice per group.  All patients received dextrose according to the protocol.

There was a significant difference in the reduction of serum potassium between the 5 and 10 unit groups: -0.63 mmol/L vs -0.9 mmol/L (p 0.001).

Bottom line:  Hypoglycemia occurred even with insulin dose reduction.  Potassium lowering was higher in patients who received the 10 unit dose.

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• Use of FAST is less common in pediatric trauma than in adult trauma
• FAST in pediatric trauma has a lower negative predictive value than in adults
  • 1/3 of pediatric patients with hemoperitoneum on CT will have a negative FAST
  • Lowest sensitivity and specificity is in the under 2 years age group
• A 2017 randomized clinical trial of ~900 patients showed no difference in clinical care, use of resources, or length of stay in hemodynamically stable children who received FAST + standard trauma evaluation versus standard trauma evaluation alone
• There may be a role for FAST as a screening in patients with low suspicion for intraabdominal injury in conjunction with labs and physical exam, but this has not been fully explored

Bottom line: A positive FAST warrants further workup and may be helpful in the hemodynamically unstable pediatric trauma patient, but a negative FAST does not exclude intraabdominal injury and evidence for performing FAST in hemodynamically stable pediatric patients is limited.

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Background: It is classically taught that the tenets of DKA management are IV fluids, electrolyte repletion, and an insulin infusion that is titrated until approximately 2 hours after anion gap closure, when long-acting subcutaneous insulin is administered if the patient is tolerating oral intake. It has been previously found that earlier administration of subcutaneous long-acting insulin can shorten the time to anion gap closure, while other small studies have noted similar efficacy in subcutaneous insulin compared to IV in mild/moderate DKA. 

A recent JAMA article presents a retrospective evaluation of a prospectively-implemented DKA protocol (see "Full In-Depth" section) utilizing weight-based subcutaneous glargine and lispro, rather than IV regular insulin, as part of initial and ongoing floor-level inpatient treatment.

When compared to the period before the DKA protocol: 

• ICU admissions decreased (27.9% from 67.8%, p<0.001)
• There was no difference in overall amount of insulin and time to anion gap closure
• There was no difference in 30-day mortality
• There was no difference in incidence of hypoglycemc events.

The only exclusion criteria were age <18 years, pregnancy, and presence of other condition that required ICU admission. 

Bottom Line: Not all DKA requires IV insulin infusion.

At the very least, we should probably be utilizing early appropriate-dose subcutaneous long-acting insulin. With ongoing ICU bed shortages and the importance of decreasing unnecessary resource use and hospital costs, perhaps we should also be incorporating subcutaneous insulin protocols in our hospitals as well.

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The radial nerve is susceptible to compressive neuropathy against the spiral grove of the humerus which can lead to neuropraxia.

When the upper arm is compressed against a chair back or bar edge sometimes from a lost battle with alcohol:  Saturday night palsy.

When another individual sleeps on someone’s arm overnight compressing the radial nerve:  Honeymoon palsy

From nerve compression from improper technique with crutches:  Crutch palsy

If diagnosis not clear from history, DDx includes other entities that can also present with isolated wrist, thumb/finger drop

Horses:  Radial verve palsy, CVA, C7 compression

• Most central disorders that cause arm weakness affect extensor muscles to a greater degree than the flexors.

Zebras:  Lead toxicity, acute porphyrias (often polyneuropathy but upper extremity before lower and frequently distal extensors

Careful history and exam important in differentiating

In cases of peripheral compression against the spital groove the triceps maintains strength.

The distal extensors lose strength (wrist and fingers)

Including the thumb abduction (abductor pollicis longus is radial-innervated)

AND so will the brachioradialis

The brachioradialis (despite being a forearm flexor) has dual innervation from the radial nerve in 80% of people.

Brachioradialis strength is often preserved in a central lesion.

            Best tested with arm supported on a surface in mid pronation/supination (hammer curl position) and have patient flex against resistance and evaluate muscle strength and bulk.

Although it is well-documented that there is no true "maximum" dose of vasopressor medications, further blood pressure support as doses escalate to very high levels tends to be limited.  As such, debate has raged in Critical Care as to when is the "right" time to start a second vasoactive medication.  The VASST trial (Russell et al, NEJM, 2008) is considered to be the landmark trial in this area, and found a trend towards improvement with early addition of vasopressin to norepinephrine, but no statistically significant difference, and may have been underpowered.  

Partly as a result of VASST, the pendulum has tended to swing towards maximizing a single vasoactive before adding a second over the past decade.  The relatively high cost of vasopressin in the US has also driven this for many institutions.  However, more recently a "multi-modal" approach, emphasizing an earlier move to second, or even third, vasoactive medication, is increasingly popular.  Although cost is often prohibitive for angiotensin-2 given controversial benefits, many now advocate for targeting adrenergic receptors (e.g. with norepinephrine or epinephrine), vasopressin receptors (e.g. with vasopressin or terlipressin) and the RAAS system (e.g. with angiotensin 2) simultaneously in patients with refractory shock.  A recent review by Wieruszewski and Khanna in Critical Care (see references) outlines this approach well. 

Bottom Line: When to add a second vasoactive medication (e.g. vasopressin) for patients with refractory shock after a first vasoactive is controversial and not known.  Current practice is trending towards earlier addition of a second (or third) agent, especially if targeting different receptors, but there is limited high-quality evidence to support this approach.  Many practicioners (including this author) still follow VASST and consider vasopressin once doses of around 5-15 micrograms/min (non-weight based) of norepinephrine are reached.

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Vasopressor Tips in the Critically Ill

• Critically ill patients often require the administration of vasopressors to maintain adequate organ perfusion.
• A few tips to consider when administering vasopressors include:
  • Titrate to mean arterial blood pressure (MAP) or diastolic blood pressure goals.  Systolic blood pressure (SBP) is not a key driver of perfusion pressure.
  • As vasopressors also result in venoconstriction and can increase venous return, early initation may limit the need for overly aggressive fluid resuscitation.
  • Vasopressors can be safely administered through an appropriately placed peripheral venous catheter.
  • There is no maximal dose of vasopressors.
  • Consider vasopressors with a different mechanism of action in patients with persistent shock refractory to the initial vasopressor agent.

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Head Impact Exposure and Concussion Incidence

There has been a major focus on head impact biomechanics as a cause of single-impact concussion in football.

The role of repeated subclinical (without diagnosed concussion) head impact exposure (HIE)

during the preseason and regular season may also be contributory.

There may exist individualized concussion tolerance levels. This threshold may be reduced by the burden of sustained subconcussive impacts

NCAA Division 1 football athletes sustain a median of 426 impacts over the course of a football season

            652 impacts/season in high school football

Total head impact exposure during the preseason occurred at 2x the rate of the regular season

This association was investigated over 1120 athlete seasons from 6 NCAA D1 football programs across 5 years

Head Impact Telemetry was used to record head impact exposure

Elevated preseason HIE was strongly associated with preseason and in season concussion incidence

Total season HIE was strongly associated with total season concussion incidence.

Conclusion: There is a prolonged effect of HIE on concussion risk starting with preseason football.

Athletes with higher preseason HIE may have higher risk of concussion for the entire fall season.

In Practice: 

In 2016, the Ivy League eliminated full contact practices from the regular season in addition to their existing limits on the amount of full contact in practice during the spring and preseason.

Currently, the NCAA has the following limitations:  Teams won’t be allowed to hold full-contact practices on more than two days in a row. Each practice session is limited to only 75 minutes of full contact, in addition to a limit of two preseason scrimmages.

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Enthusiasm for early transfusion of blood products in patients with traumatic shock has increased with increasing availability of pre-hospital blood and plasma and results of studies such as the PAMPer trial of pre-hospital plasma have shown potential mortality benefits.  The deployment of prehospital blood for patients in hemorrhagic shock is promising but has significant cost and logistical considerations.

The RePHILL trial was a UK pre-hospital-based study of packed red blood cells and lyophilized plasma versus normal saline in trauma patients with presumed hemorrhagic shock.  Patients older than age 16 with an SBP<90 or an absent radial pulse were eligible to get up to 1L of the study intervention.  Multiple centers took part in the trial with 1:1 randomization stratified by study center.  The primary outcome was a combination of mortality or lactate clearance less than 20% per hour or both.

A total of 432 patients were assigned a study fluid. The population was 82% male, median of 38 years old, with 78% of injuries classified as blunt, and 82% of the presumed hemorrhage classified at non-compressible. This was a very ill population with an average SBP of 73, an average GCS of 7 and an ISS of 36. The average from emergency call to EMS arrival was 30 minutes, average to study intervention was 26 minutes and time from EMS activation to ED arrival was 90 minutes.

The results showed no difference in the primary composite endpoint (64% vs 65%), with no difference in mortality (43% vs 45%) or lactate clearance (50% vs 55%).  Interestingly, patients in the blood product arm had similar vital signs, lactate, and INR on ED arrival but received more blood products in the first 24 hours after ED arrival (pRBC 6.34 vs 4.41, p=0.004 and Plasma 5.04 vs 3.37, p=0.002). The was a trend toward improved early mortality at 3hr in the pre-hospital blood group (16% vs 22%, p=0.08).

Bottom Line(s):

Prehospital packed red blood cells and lyophilized plasma as compared to saline for traumatic shock did not improve mortality or lactate clearance in a well conducted multicenter RCT. 

The use of prehospital blood products is promising but population which benefits, and the optimal type of product and delivery mechanism remain unclear.

Increased blood utilization and lower early mortality in the blood product group may represent alteration in the spectrum of disease that requires different early management.

The reasons for this counterintuitive result are unclear and further trials of whole blood as well as fibrinogen concentrates are ongoing.

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Attitudes, Behavior, and Comfort of Emergency Medicine Residents in Caring for LGBT Patients: What Do We Know?

Background

This paper was written by some of the thought leaders in the Diversity, Equity and Inclusion realm in Emergency Medicine. Undergraduate medical education has minimal formal hours dedicated to LGBTQ+ health, and EM residency has even less. The authors wanted to assess EM resident comfort in caring for patients who identify as part of the LGBTQ+ community

Methodology

An anonymous service was sent out to CORD and was then disseminated to the residents of the 167 ACGME accredited EM residencies. It was a 24-question survey based on a similar one given to medical students. Overall, a total of 319 residents responded to the survey, with the vast majority identifying as heterosexual and cisgender

Results

The results seem at first to be contradictory. A majority of respondents (63.5%) were either comfortable or very comfortable in addressing the needs of LBGT patients. But when asked about specific behaviors related to providing care, there was more to the story. Only 17.3% of respondents always asked about sexual partner gender, 4.7% always asked about sexual orientation for an abdominal or genital complaint.

Perhaps more disturbing, the survey found that 10% of respondents had observed attending physicians make discriminatory or inappropriate comments about LGBT patients or staff, 2% of respondents were uncomfortable working alongside LGBT physicians, and 6% of respondents disagreed with the statement that LGBT patients deserve the same level of quality care as other patients.

Discussion

This study was published in 2019. Despite some amazing advancement in the LGBT community, we obviously still have a long way to go. This study shows the need for more formalized and routine education regarding LGBT population health issues at both the undergraduate and graduate medical education levels. It also demonstrates that LGBT physicians still experience discrimination in the workplace, even within our specialty. Be kind, be compassionate, be understanding.

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Small Bowel Obstruction

• Although it takes about 11 minutes to diagnose SBO on ultrasound, newer studies have shown a decrease in sensitivity and specificity of SBO with 11 false negatives and 57 fall positives. So PLEASE BE CAREFUL when looking for SBO with ultrasound.
• Let’s give a shout out to one of our medical students, Alexa Van Besien, who recently took some great images of a patient with a known SBO.

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