UMEM Educational Pearls - Critical Care

With a shortage of push dose epi, this may be an opportune time to review alternative options (see also Ashley's email on the subject).

The dose of vasopressor required to reverse hypotension has been most studied in pregnant women undergoing c-section who get epidurals and experience spinal-induced vasoplegia and hypotension (not necessarily our patient population, but we can extrapolate...)  

Phenylephrine was found to reverse hypotension 95% of the time at a dose of 159 micrograms (a neo stick has 100 ug/mL, so around 1-2 mL out of the stick)

Norepinephrine reversed hypotension in 95% of patients at a dose of 5.8 ug.  The starting dose for our norepi order in Epic is 0.01 ug/kg/min, so if you have a levophed drip hanging and have an acutely hypotensive patient, you may want to briefly infuse at a higher rate such as 0.1 ug/kg/min (for a typical weight patient), or bolus approximately 3-7 ug for a typical patient.  Of course the degree of hypotension, particular characteristics of your patient and clinical context should be taken into consideration.  When your a lucky enough to have this resource, always consult your pharmacist.

Bottom Line: To reverse acute transient hypotension you may consider:

-A bolus of phenylephrine 50-200 ug (0.5-2 mL from neo-stick)

-A bolus of norepinephrine 3-7 ug

-Briefly increasing your norepinephrine drip (if you have one) to something around 0.1 ug/kg/min in a typical weight patient

-Always search for other causes of hypotension and consider clinical context.

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Question

Wound botulism presents as descending paralysis when Clostridium botulinum spores germinate in anaerobic necrotic tissue. There have been hundreds of cases in the last decade, but it is poorly reported outside of California.

Black tar heroin and subcutaneous injection (“skin popping”) carry the highest risk, but other injected drugs and other types of drug use suffice. C botulinum spores are viable unless cooked at or above 85°C for 5 minutes or longer and this is not achieved when cooking drugs. 

Early administration of botulism anti-toxin (BAT) not only saves lives but can prevent paralysis and mechanical ventilation. An outbreak of 9 cases between September 2017 and April 2018 cost roughly $2.3 million, in part because patients didn’t present on average until 48 hours after symptom onset and it took an additional 2-4 days before the true cause of their respiratory depression and lethargy were understood. One patient died.

PEARL: talk to your injecting drug users about the symptoms of botulism: muscle weakness, difficulty swallowing, blurred vision, drooping eyelids, slurred speech, loss of facial expression, descending paralysis, and difficulty breathing. Consider botulism early in your patients who inject drugs but who do not respond to naloxone or who exhibit prolonged symptoms. Testing at the health department is performed with mouse antibodies to Botulism Neurotoxin (BoNT) combined with the patient’s serum.

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Post-Arrest Prophylactic Antibiotics?

• Pneumonia is the most common infective complication in post-cardiac arrest patients. It may develop in up to 60% of patients and is associated with an increased ICU length of stay.
• Given the challenges in diagnosing pneumonia in the post-cardiac arrest patient, many clinicians consider prophylactic antibiotic administration.
• A recent systematic review and meta-analysis sought to evaluate the effect of early antibiotic use on survival and survival with good neurologic outcome in adult patients resuscitated from cardiac arrest. Key study results include:
  • 11 studies (3 RCTs, 8 observational trials)
  • 6149 patients
  • No change in overall survival or survival with good neurologic outcome
• Take Home Point: Current data does not support the prophylactic administration of antibiotics to adults resuscitated from cardiac arrest.

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Question

Little people (patients with achondroplasia or "dwarfism") have little lungs. Even though the trunk may appear to be a normal size with small limbs, the vital capacity is actually about 75% the predicted value based on the patient's sitting height. Macrocephaly and a decreased anterior-posterior depth are the cause for this. When you want to mechanically ventilate a little person, you can estimate their height based on a typical person with the same sitting height, but their actual volume will be about 3/4 the tidal volume predicted.

When intubating, remember these patients also have a high risk of basicranial hypoplasia (the foramen magnum may be small and key-hole shaped). These patients will be predisposed to compress the vertebral arteries when you tilt the head back and this itself can cause ischemia of the medulla and pons leading to central apnea.

Stokes DC, Wohl ME, Wise RA, et al. The lungs and airways in Achondroplasia. Do little people have little lungs? CHEST. 1990; 98(1):145-52

Pauli RM. Achondroplasia: A comprehensive review. Orphanet Journal of Rare Diseases. 2019; 14(1): 

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Some patients with severe pulmonary hypertension receive continuous infusions at home of prostacyclins, such as epoprostanol (flolan).  These are generally delivered via a pump that the patient wears, which is attached to an indwelling catheter.  As with any indwelling device, they are at risk for infection and other complications, including malfunction.

Interruption of delivery of the medication can result in rapid cardiovascular collapse, sometimes within minutes.  In this instance, the medication should be resumed as quickly as possible (by a traditional IV if the catheter is not functional), and the patients should be treated as one would approach a patient with decompensated right heart failure.

I once saw a patient in the ED whose listed chief complaint was "medication refill", but was actually there for dislodgement of her prostacyclin catheter (thankfully she was ok).  With more patients receiving devices they are dependent upon (insulin pumps, AICDs, prostacyclin catheters), be wary of chief complaints such as "medication refill" or "device malfunction."

Bottom Line: Interruption of continuous prostacyclin therapy for pulmonary hypertension can be rapidly fatal and should be addressed immediately.

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Question

In a study of alarms from 77 monitored ICU beds over the course of a month at the University of California, San Francisco, false alarms were common. Accellerated Ventircular Rhythms (AVRs) made up roughly one third of the alarms, and of the more than 4,361 AVRs, 94.9% were false while the remaining 5.1% did not result in a clinical action.

While this study had a majority of patients in the Med/Surg ICUs, a minority were from the cardiac and neurologic ICUs giving it some broad applicability. This study adds to the literature indicating there are subsets of alarms which may not be necessary or which may require adjustment to increase specificity.

Suba S, Sandoval CS, Zegre-Hemsey J, et al. Contribution of Electrocardiographic Accelerated Ventricular Rhythm Alarms to Alarm Fatigue. American Journal of Critical Care. 2019; 28(3):222-229

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• ANDROMEDA-SHOCK compared using capillary refill time versus lactate clearance as a guide for resuscitation in septic shock patients
• The cap refill group showed better SOFA scores at 72 hours, and a trend to lower mortality
• In the study, cap refill was performed by pressing a glass microscope slide to the ventral surface of the second finger distal phalanx, holding until blanched for 10 seconds, and releasing.  Cap refill > 3 seconds was considered abnormal.

Bottom Line: Consider using capillary refill as an alternate (or complimentary) endpoint to lactate clearance when resuscitating your septic shock patients.

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Management of Coagulopathy in Acute Liver Failure

• Patients with acute liver failure (ALF) frequently require rapid resuscitation to prevent decompensation and multiorgan failure.
• The most common cause of ALF remains drug-induced injury (i.e., acetaminophen).
• Though coagulopathy is common in patients with ALF, the prophylactic administration of blood products has not been shown to have clinical benefit.
• The routine correction of coagulation abnormalities is not currently recommended, unless the patient undergoes a major procedure (e.g., liver transplant).

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Many, if not nearly all, of our intubated patients in the ED have altered mental status, a potential to clinically worsen, or a requirement for medications that would alter their respiratory status (e.g. propofol, opioids, paralytics).  It is imperative to place these patients on appropriate ventilator modes to avoid apnea when their respiratory status changes.

• Spontaneous modes (see partial list below) REQUIRE patients to initiate breaths on their own.  No ventilation occurs in a true spontaneous mode without patient effort.  
• Patients who have alterations in respiratory drive, neuromuscular function, or are receiving paralytics should NOT be placed on:
  • Pressure Support (PSV),
  • Volume Support (VSV),
  • CPAP/BiPAP/APAP,
  • Pressure-Assisted Ventilation (PAV) / Proportional Pressure Support (PPS),
  • or other spontaneous modes
• Our hypothermia order set includes a prn paralytic (cisatracurium infusion, vecuronium bolus) to combat shivering.  Discontinue these medications for patients on spontaneous modes.
• Our Servo-I ventilators automatically backup to a control mode (VS-->VC, PS-->PC) after a period of apnea (default is anywhere from 15-45 seconds, but it depends on how the RT has set the ventilator) as a safety mechanism, but this could still cause dangerous hypoxia or hypercapnea in severely ill patients.
• If the mechanics of pressure support are desired in patients at risk of apnea, there are other methods to achieve this (PC, descending flow VC, SIMV VC+PS with a low rate, and others).
• Always consult your RT when changing ventilator settings, and be sure to take vent alarms seriously.

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Attachments

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Question

Gallstones account for 35-40% of cases of pancreatitis and the risk increases with diminishing stone size. Bile reflux into the pancreatic duct can form stones there, beyond where they can be visualized by ultrasound. Biliary colic may precede the pancreatitis, but not necessarily. The pain typically reaches maximum intensity quickly but can remain for days.

Alanine aminotransferase (ALT) > 3x normal is highly suggestive of biliary pancreatitis.

Abdominal ultrasound is not sensitive to common bile duct stones but may find dilation.

In the absence of cholangitis, endoscopic ultrasound or MRCP are sensitive tests and permit intervention. Patients who recover are much more likely to develop cholangitis, therefore cholecystectomy is indicated in patients after they recover from gallstone pancreatitis.

Bottom Line: a patient presenting with days of abdominal pain but an absence of gallstones or cholangitis may still suffer from gallstone pancreatitis which requires further intervention, including cholecystectomy.

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Mechanical Ventilation in the Obese Critically Ill

• Rates of obesity have steadily risen over the past three decades.  In fact, the prevalance of obesity in the ICU is now estimated at 20%.
• Obesity affects numerous organ systems and impacts the resuscitation and management of these patients.
• The pulmonary systems undergoes several changes that include decreased lung compliance, decreased chest wall compliance, increased O2 consumption, increased CO2 production, and increased work of breathing.
• When initiating mechanical ventilation in the obese patient without ARDS, consider the following initial settings:
  • Tidal volume 6 ml/kg ideal body weight
  • PEEP of 10-12 cm H2O
  • RR to achieve a PaCO2 35-45 mmHg
  • FiO2 to maintain SpO2 92-95%
  • Driving pressure < 15 cm H2O

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Background:  Previous systematic reviews^1,2,3 have indicated that the absence of cardiac activity on point-of-care ultrasound (POCUS) during cardiac arrest confers a low likelihood of return of spontaneous circulation (ROSC), but included heterogenous populations (both traumatic and atraumatic cardiac arrest, shockable and nonshockable rhythms).

The SHoC investigators⁴ are the first to publish their review of nontraumatic cardiac arrests with nonshockable rhythms, evaluating POCUS as predictor of ROSC, survival to admission (SHA), and survival to discharge (SHD) in cardiac arrests occurring out-of-hospital or in the ED.

• 10 studies, 1485 patients
• Compared to absence of cardiac activity, presence of cardiac activity = higher odds, increased incidence of ROSC, SHA, and SHD
• Pooled sensitivity for ROSC, SHA, SHD relatively low (60%, 75%, 69%, respectively)
  • On subgroup analysis, sensitivity higher in PEA group (77%) than asystole group (25%)

Bottom Line:  In nontraumatic cardiac arrest with non-shockable rhythms, the absence of cardiac activity on POCUS may not, on its own, be as strong an indicator of poor outcome as previously thought.

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The Lung Transplant Patient in Your ED

• Infections are the most common reason for ICU admission in lung transplant patients.
• Not surprisingly, healthcare-aquired pneumonia is the most common infection seen in lung transplant recipients.
• In contrast to non-transplant patients, gram-negative bacteria (i.e., Pseudomonas aeruginosa) are the most common pathogens.
• Be sure to include antimicrobial coverage for Pseudomonas in your lung transplant patients presenting to the ED with pneumonia.

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When managing transplant patients it is important to keep in mind the anatomic and physiologic changes that occur with the complete extraction of one person's body part to replace another's. 

For cardiac transplant patients with symptomatic bradycardia:

• Remember that due to lack of autonomic/vagal innervation, resting HR should be around 90 bpm.
• HR will not respond to atropine. Use direct sympathomimetics like epinephrine instead.
• If medication is unsuccessful, proceed to transcutaneous or transvenous pacing.

For cardiac transplant patients with tachyarrythmias:

• They are particularly sensitive to adenosine; for SVT start with 1 to 3mg adenosine push (3mg is usually effective) to avoid sustained bradycardia or asystole.
• Digoxin is not effective as an antiarrhythmic.
• Diltiazem can decrease the metabolism of calcineurin inhibitor immunosuppressive agents (such as cyclosporine and tacrolimus), so while it can be used there may need to be dose adjustments to these medications. 

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Hyponatremia in the Brain Injured Patient

• Hyponatremia is the most common electrolyte disorder in neurocritical care and is associated with increased ICP.
• The two most common causes of hyponatremia in this patient population are cerebral salt wasting syndrome and SIADH.
• Symptomatic hyponatremia should be treated with hypertonic saline:
  • 30-45 ml of 10% NaCl or
  • 100-150 ml of 3% NaCl
• In order to prevent osmotic demyelination syndrome (ODM), sodium should not be corrected by more than 10 mmol/L/day.
• The risk of ODM is low when acute hyponatremia develops in less than 48 hours.

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The PROTRACH study recently compared preoxygenation with standard bag valve mask (BVM) at 15 lpm to preoxygenation + apneic oxygenation with high flow nasal cannula 60 lpm/100% FiO2 in patients undergoing rapid sequence intubation.

• There was no significant difference in the primary outcome of median lowest SpO2 during intubation. 
• There were more intubation complications in the BVM group compared to the HFNC group:
  • Severe complications: SpO2 <80%, severe hypotension (SBP < 80mmHg or vasopressor initiation/increase by 30%), and cardiac arrest (6% HFNC vs 16% BVM, RR 0.38, 95% CI 0.15-0.95, p=0.03). 
  • Moderate complications: aspiration, cardiac arrhythmia, agitation, and esophageal intubation (0% HFNC vs 7% BVM, p= 0.01). 
• There was no difference in ventilator days, ICU length of stay, or mortality.

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A True Tracheostomy Emergency

• Patients with a tracheostomy often present to the ED for evaluation of a potential complication.
• Consider a tracheoarterial fistula in any patient with a tracheostomy who presents with brisk bleeding.
• Most occur within 3 to 4 weeks following tracheostomy placement, and the most common location is the innominate artery.
• Up to 50% of patients will present with a sentinel bleed - an episode of brisk bleeding that has usually stopped at the time of presentation.
• For patients who present with active hemorrhage, overinflate the tracheostomy cuff in an attempt to tamponade the bleeding.
• If that does not stop the bleeding, remove the tracheostomy and compress the artery against the poterior sternum with your finger.

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Despite ongoing research and efforts to improve our care of patients with ARDS, it remains an entity with high morbidity and mortality. Early recognition of the disease process and appropriate management by emergency physicians can have profound effects on the patient's course, especially in centers where ICU boarding continues to be an issue.

Recognition of ARDS (Berlin criteria)

• Acute in onset
• Bilateral infiltrates on chest imaging not due to cardiac failure/volume overload
• PaO2 : FiO2 < 300 despite PEEP of at least 5cmH2O 
• This is the standard ED patient who gets intubated with multifocal pneumonia and has continued hypoxemia

*An ABG should be obtained in the ED if physicians are unable to wean down FiO2 from high settings, if oxygenation by pulse ox is marginal, or if the patient is in a shock state.

Tenets of ARDS Management:

• Low tidal volume ventilation (6-8ml/kg ideal body weight*)
• Maintain plateau pressures (Pplat) < 30 cmH2O
• Driving pressure (Pplat – PEEP) < 15 cmH2O
• Goal PaO2 > 55-60 
• Permissive hypercapnia to pH >7.2

*IBW Males = 50 + 2.3 x [Height (in) - 60]   /  IBW Females = 45.5 + 2.3 x [Height (in) - 60]

Strategies for Refractory Hypoxemia in the ED:  You can't prone the patient, but what else can you do? 

1. Escalate PEEP in stepwise fashion

• ex: 2cmH20 every 10 minutes
• can use ARDSnet PEEP/FiO2 table as guide

2. Recruitment maneuvers

• "20 of PEEP for 20 seconds" or "30 for 30"
• if patient is "PEEP responsive," leave PEEP on a higher setting than when you started (ex: 10 instead of 5, 16 instead of 10)
• Risk of barotrauma with higher PEEPs and hypotension in underresuscitated or hemodynamically unstable patients due to decreased venous return

3. Appropriate sedation and neuromuscular blockade

• promotes patient synchrony with lung protective settings
• can result in improved oxygenation by itself

4. Inhaled pulmonary vasodilators (inhaled prostaglandins, nitric oxide) if known or suspected right heart failure or pulmonary hypertension

Bottom Line: Emergency physicians are the first line of defense against ARDS. Early recognition of the disease process and appropriate management is important to improve outcomes AND to help ICU physicians triage which patients need to be emergently proned or even who should potentially be referred for ECMO. 

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Does This Patient Have Pericardial Tamponade?

• Echocardiography is critical for the identification of a pericardial effusion and rapid diagnosis of pericardial tamponade.
• Common echocardiography findings that suggest tamponade include diastolic right ventricular collapse, systolic right atrial collapse, a plethoric IVC with minimal respiratory variation, and potentially exaggerated respiratory cycle changes in mitral and triscupid inflow velocities.
• Of these, systolic right atrial collapse is the earliest echocardiographic sign of tamponade, with a sensitivity ranging from 50% to 100%.
• Of the 4 standard echo views, systolic right atrial collapse can best be viewed in the apical 4-chamber and subxiphoid views.

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Neutropenic enterocolitis can occur in immunosuppressed patients, classically those being treated for malignancy (hematologic much more commonly than solid tumor). When involving the cecum specifically, it is known as "typhlitis."

It should be considered in any febrile neutropenic patients with abdominal pain or other symptoms of GI discomfort (diarrhea, vomiting, lower GI bleeding), and can be confirmed with CT imaging.

A recent study found that invasive fungal disease, most often candidemia, occurred in 20% of febrile neutropenic patients with CT-confirmed enteritis, a rate that increased to 30% if the patient was in septic shock.

Take Home: 

1. Have a lower threshold for abdominal CT imaging in your patients with febrile neutropenia and abdominal pain/GI symptoms, especially if they are critically ill.

2. Consider addition of IV antifungal therapy if they are hemodynamically unstable with enterocolitis on CT.

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