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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• A recent retrospective study examined CT radiation doses in different types of facilities

• Mean patient age: 12 years
• Authors reviewed radiation doses for nearly 240,000 CT scans in over 500 facilities
•  
• The facilities were categorized into 4 groups: 

• 1) academic pediatric,
• 2) non-academic pediatric,
• 3) academic adult, 
• 4) non-academic adult

Most (65%) scans were performed at nonacademic adult centers

• Radiation doses were significantly higher at adult facilities vs. pediatric facilities
• Also, radiation doses were higher at non-academic vs. academic facilities
• For example, the largest children received twice the radiation dose for abdomen-pelvis CT scans performed at nonacademic adult facilities compared with academic pediatric facilities
  • 11.9 mGy vs. 5.8 mGy
• Academic pediatric facilities use lower radiation doses than do nonacademic pediatric or adult facilities for all head CT examinations and for the majority of chest and abdomen-pelvis

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Over 630,000 children visit the ED every year with a diagnosis of concussion

Predictors of persistent post-concussive symptoms (PPCS):

• female sex
• age over 13 years
• previous concussive symptoms lasting over 1 week
• headache
• sensistivity to noise
• fatigue
• slow response to questions.

Appromixately 1/3 of pediatric patients will have PPCS lasting over 2 weeks

Likelihood of PPCS increases to >50% in those with risk factors identified in the ED

Every state has a youth concussion law. The basic tenants are a) immediate removal from play b) written clearance from health professional to return to play c) education for athlete, parents, coaches.

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• Hypertonic saline and mannitol are commonly used for management of acute intracranial hypertension and cerebral herniation.
• The choice of medication is often limited by venous access.
• 23.4% NaCl has been shown to decrease intracranial pressure in patients refractory to mannitol.
  • It requires administration through a central line to avoid sclerosis of the peripheral veins and tissue necrosis with extravasation.
• Intraosseous (IO) access provides a more rapid route for 23.4% NaCl administration.
  • No complications were observed relating to IO insertion site.
  • Transient hypotension occurred in more patients who received 23.4% NaCl via IO vs. central line.

Bottom Line: Use of IO allows more rapid administration of 23.4% NaCl with no immediate serious complications.

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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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Elderly patients (mean age of 84 years) living in the community who are seen and discharged from the Emergency Department due to illness or injury are at increased risk for further disability and functional decline for at least six months after their visit.  This is associated with increased mortality, cost and need for long term care in previously self-functioning individuals. *   When appropriate to discharge from the ED, we should consider discharge planning that includes coordination with care management services to be sure these individuals have adequate home support systems in place and access to close outpatient follow-up. 

*It should be noted that the risk is even greater after inpatient hospitalization.

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Identifying serotonin syndrome in the emergency department can be difficult without an accurate patient history. Furthermore, the physical symptoms may look similar to many other disorders such as neuroleptic malignant syndrome and anticholinergic toxicity. If you remember the acronym SHIVERS, you can easily recognize the signs and symptoms of serotonin syndrome.

Shivering: Neuromuscular symptom that is unique to serotonin syndrome

Hyperreflexia and Myoclonus: Seen in mild to moderate cases. Most prominent in the lower extremities. This can help differentiate from neuroleptic malignant syndrome which would present with lead-pipe rigidity.

Increased Temperature: Not always present, but usually observed in more severe cases

Vital Sign Abnormalities: Tachycardia, tachypnea, and labile blood pressure

Encephalopathy: Mental status changes such as agitation, delirium, and confusion

Restlessness: Common due to excess serotonin activity

Sweating: Autonomic response to excess serotonin. This symptom can help differentiate from anticholinergic toxicity in which the patients would present with increased temperature but dry to the touch

Once serotonin syndrome is identified, it is important to discontinue all serotonergic agents, provide supportive care with fluids, and sedate with benzodiazepines. Sedation with benzodiazepines helps to decrease myoclonic jerks which also helps with temperature control. If patients are hyperthermic, they will require intensive cooling. Cyproheptadine, a potent antihistamine and serotonin antagonist, should also be administered. The initial dose of cyproheptadine in serotonin syndrome is 12mg which can be followed by 2 mg every 2 hours as needed for symptom control.

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Intravenous lipid emulsion (ILE) is use as a therapy of last resort in refractory cardiovascular shock from toxicity of select agents (e.g. calcium channel blockers, beta blockers and select Na-channel blocking agents). There are number of case reports/series that showed positive cardiovascular/hemodynamic response after ILE, which are prone to publication bias. Results from limited number of human trials  have shown mixed results.

A study reviewed fatal cases of poisoning that received ILE from the National Poison Data System to characterize the clinical response of ILE therapy.

Results

N=459 cases from 2010 to 2015.

Most common substance involved

*Use of ILE supported by Lipid work group

Response rate

• No response: 45%
• Unknown response: 38%
• Transient/minimal response: 7%
• ROSC: 7%
• Immediate worsening: 3%

Possible adverse reactions (n)

• ARDS: 39
• Lipemia: 3
• Failure of CRRT filter: 2
• Worsening/new seizure: 2
• Asystole immediately after administration: 2
• Fat embolism: 1

Conclusion

• The number of failed cases of ILE therapy outnumbers the published cases of ILE success.
• Currently, there is a lack of data that shows the efficacy of ILE therapy.

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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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• Pediatric visits for behavioral and mental health issues is on the rise.
• From 2008 to 2015, rates of PED visits for suicidal thoughts/attempts doubled.
• Shortage of pediatric psychiatrists:  8,300 nationwide with a need for 30,000.
• Deinstitionalized Movement of 1980's, has worsened this ED crisis-based culture.
• 50% of all mental illness begins by age 14.
• 1 in 5 children experience a mental disorder in a given year.
• Aggressive or agitated behavior in pediatric patients is different from adults.
• Children are more amenable to environmental and behavioral techniques, especially verbal de-escalation, once a trigger is identified.
• If not successful, avoid physical restraints and consider medications instead.
• Review current or previously prescribed medications, and consider extra/early/higher dosing. If naive to medications:
• First line is Diphenhydramine.
• Followed by Chlorpromazine, Risperidone, and Olanzapine
• Thorazine should be avoided in children under 12 years due to extra-pyramidal effects.
• Lorazapam not recommneded in children under 12 years, as it can cause disinhibition and worsen behavior.
• Avoid sedating children with neurodevelopmental disorders as they can have paradoxical reactions to diphenhydramine and benzodiazepines, and antipsychotics sometimes are not as effective.
• Boarding is common due to lack of resources, so starting treatment in the ED is imperative. 

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Scromboid (histamine fish poisoning) can be easily misdiagnosed since its' clinical presentation can mimic that of allergy. Seen most frequently in the summer and occurring with Scombroideafish (tuna, mackerel, bonito, skipjack) but also with large dark meat fish (sardines and anchovies) and even more commonly with nonscromboid fish such as mahi mahi and amber jack. In warm conditions when fish is improperly refrigerated, bacterial histidine decarboxylase converts muscle histidine into histamine which quickly accumulates. Histamine is heat stable and not destroyed with cooking. 

• Clinical features: Intense flushing of face, neck, and upper torso, urticaria, abdominal cramps, headache, palpitations, diarrhea, nausea, vomiting, burning of the mouth and throat.
• Symptoms begin within minutes of ingestion and typically last several hours
• Self limiting condition. Mainstay of treatment is H1 blockers (antihistamines) and good supportive care. If bronchospam present steroids and inhaled B2 agonists should be administered.

Bottom Line:

Scromboid poisoning is due to histamine ingestion and is often misdiagnosed as allergic reaction. It is preventable with proper fish storage.

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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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Laboratory testing for Spinal Epidural Abscess

CBC

The CBC is poorly sensitive/specific

The WBC count may be nml or elevated

Left shift and bandemia may or may not be present

ESR and CRP

Sensitive but not specific

Elevated in >80% with vertebral osteomyelitis.

• Sensitive for spinal infection, but not extremely specific.

• ESR
  • ESR was elevated in 94-100% of patients with SEA vs. only 33% of non-SEA patients
• CRP
  • Less useful for acute diagnosis since CRP levels rise faster and return to baseline faster than ESR
    • Elevated CRP seen in 87% of patients with SEA as well as in 50% of patients with spine pain not due to a SEA
  • Better used as a marker of response to treatment.

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• Misdiagnosis of neurologic emergencies can result in serious neurologic dysfunction or death.
• A recent retrospective analysis using AHRQ databases looked at >3 million adults discharged from the ED with diagnoses of atraumatic headache or back pain.
• A serious neurologic condition or death occurred within 30 days after ED discharge in:
  • 0.5% of patients with nonspecific diagnosis of headache
  • 0.2% of patients with nonspecific diagnosis of back pain
• The frequency of adverse outcome was highest between days 1 and 3 after ED discharge.
• The most frequent adverse outcome was ischemic stroke (18.1%) for headache and intraspinal abscess (44%) for back pain.
• Age ≥ 85, male sex, non-Hispanic white, comorbidities such as neurologic disorders, HIV/AIDS, and malignancy were associated with higher incidence of adverse outcome.

Bottom Line: The rate of serious neurologic conditions missed at an initial ED visit is low.  However, the potential harm of misdiagnosis can be substantial.

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Kratom (Mitragyna speciosa) has been used for centuries in Southeast Asia to manage pain and opium withdrawal. It is increasingly being used in the U.S. for similar purpose. The U.S. DEA lists Kratom as a “drug of concern”.

Effects of Kratom leaves

• 1 – 5 gm: mild stimulatory effects
• 5 – 15 gm: opioid-like effects
• >15 gm: sedative effects

A study reviewed National Poison Data System (2011 to 2017) to evaluate the clinical effects/outcomes of Kratom exposure.

Finding: (N=1807; single-substance: 1174; multiple-substance: 633])

• 2/3 of all exposure occurred in 2016 – 2017 via oral route (83.0%)
• 88.9% were adults (> 20 years old) 
• 86.1% of the exposures occurred in private residence
• Fatality: 11 (2 deaths occurred after an isolated exposure to Kratom)

Common symptoms

• Agitation: 22.9%
• Tachycardia: 21.4%
• Drowsiness/lethargy: 14.3%
• Nausea/vomiting: 13.2% - 14.6%
• Confusion: 10.6%
• Hypertension: 10.1%
• Seizure (single/multiple): 9.6%
• Respiratory depression: 3.6%

Disposition

• Admitted to a health care facility: 31.8% (n=498)
  • Critical care unit: 14.0%
  • Non-critical care: 13.1%
  • Psychiatric facility: 4.7%

Bottom line:

• Kratom use is associated with a wide spectrum of clinical signs/symptoms.
• Death from isolated exposure to Kratom is rare. 

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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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Cauda Equina Syndrome (CES)

A recent pearl discussed CES. This is a very challenging diagnosis to make, especially on initial presentation

The 5 “classic” characteristic features are

•  Bilateral radiculopathy
• Saddle anesthesia
• Altered bladder function
• Loss of anal tone
• Sexual dysfunction

Not all symptoms will be present in a given patient and there is no sign/symptom combination that either reliably diagnoses or excludes CES.

To illustrate how difficult this diagnosis is to make, a study looked at the predictive abilities of Neurosurgical residents.

Positive MRI for CES was accurately predicted by senior neurosurgical residents in approximately 50% of patients suspected of CES based on history and physical findings. As clinical certainty only becomes apparent with the classic symptoms (which are generally late findings) waiting to initiate MRI will delay decompressive surgery and can lead to worsened functional outcomes. This leads to increased MRI demand with more negative MRIs. Not surprisingly, only ~20% of MRI scans for suspected CES are positive.

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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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