• Asterixis is a tremor of the wrist that occurs when the wrist is extended (dorsiflexed).
• It is also often referred to as a "flapping tremor" or "liver flap."
• Asterixis results from arrhythmic, interrruptions of voluntary muscle contraction resulting in brief lapses in posture.
• It is most often associated with hepatic encephalopathy that results from abnormal metabolism of ammonia to urea, causing brain cell damage.  The subsequent elevated levels of ammonia are due to liver failure.
• In addition to hepatic enephalopathy, asterixis can also be associated with the following conditions:

               -- azotemia

               -- cardon dioxide toxicity

              -- metabolic encephalopathies

              -- Wilson's Disease

Bicarbonate for severe lactic acidosis from shock?

• In critically ill patients, one of the most common causes of acidosis is hypoperfusion induced lactic acidosis
• Importantly, the source of lactic acid during hypoperfusion/shock is intracellular, and the intracellular compartment is not readily accessible to extracellular bicarb
• Exogenous bicarbonate will certainly raise extracellular pH but does not readily correct intracellular acidosis
• This increase in pH is transient and typically lasts approximately 30 minutes
• In studies to date, exogenous bicarbonate did raise pH, serum bicarbonate concentrations, and P_aCO₂ but importantly did not improve cardiac output, mean arterial pressure, or sensitization to catecholamines
• Take Home Point: Based on available literature, there is no utility to giving bicarbonate in hypoperfusion induced lactic acidosis when the pH is > 7.0

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Patients with HIV are at increased risk for several cardiovascular complications of the disease. The most common cardiac manifestation in HIV disease is reported to be pericardial effusion. 

The presence of a pericardial effusion in HIV is a poor prognostic sign, an independent predictor of mortality (62% mortality at 6 mos is reported, compared to 7% in those without effusion).

The pericardial effusion is often associated with TB in endemic areas, but can also be associated with other organisms including Staph, Strep, Chlamydia, and some viruses. HIV itself can cause an effusion as part of a generalized serous effusive process.

Takeaway: In late-stage HIV patients with any cardiopulmonary complaints, it would be prudent to make bedside ED ECHO part of your usual initial evaluation.

[reference: Khunnawat C, Mukerji S, Havlichek D, et al. Cardiovascular manifestations in human immunodeficiency virus-infected patients. Am J Cardiol 2008;102:635-642. Authors are from Michigan State Univ.]

Biliary Colic and Narcotics:

It is common to give patients with biliary colic narcotics inorder to relieve their pain.  It was common teaching in the past that Morphine should be avoided due to the fact that it could cause spasm of the spincter of Oddi.  It is now known that all narcotics, even meperidine, can cause spasm or irritation of the spincter of Oddi.

So this weeks pearls are:

1. Morphine and diluadid can be used to relieve the pain associated with biliary colic.
2. However, narcotics should be avoided at least 4 hours prior to a HIDA scan as it can affect the length of the exam and the sensitivity of it.  A HIDA scan can take up to four hours to perform, however, morphine is typically given during the test as it can shorten the exam time to 1.5 hours by increasing filling of the gallbladder through the cystic duct. 

Many things can be fatal with only one pill or sip for a young child.  One teaspoonful of Oil of wintergreen (5ml) contains about 7000 mg of salicylate (the equivalent of about 21 adult aspirin).  It would take only one swallow of Oil of wintergreen to be lethal for a young child.

Other Potential single dose killers for your Pediatric patients:

Alchohols

Methanol
Ethylene glycol
Isopropanol

Antidepressants

Monoamine oxidase inhibitors
Cyclic antidepressants

Antihypertensives

Clonidine
Verapamil
Diltiazem

Antimalarials

Chloroquine
Quinine

Benzocaine

Caustics

Hydrofluoric acid
Ammonia fluoride/bifluoride
Boric acid
Selenious acid
Disk batteries

Herbals

Eucalyptus oil
Pennyroyal oil
Camphor
Oil of wintergreen

Hydrocarbons

Imidazolines

Oxymetazoline
Naphazoline
Xylometazoline
Tetrahydrozoline

Insecticides/Rodenticides/Herbicides

Organophosphates
Carbamates
Lindane
Paraquat
Diquat
Nicotine

Opioids

Diphenoxylate
Methadone
Morphine
Oxycodone
Propoxyphene

Sulfonylureas

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Buprenorphine (Suboxone)

• Use in opioid maintenance therapy programs, doesn't have QT prolongation and less respiratory depression than methandone
• Patients must been maintained on <40mg of methadone for successful conversion to buprenorphine to take place
• Primary caregivers can prescribe after taking a course
• Partial agonist can actual precipitate withdrawal if patient takes a full opioid (say sneaking a little heroin before appointment)
• Suboxone is buprenorphine+naloxone, since naloxone has poor bioavailability when taken appropriately there is no effect but if the tablet is crushed and injected the patient will go into florid withdrawal.
• Use and abuse has been steadily increasing and death can still occur from overdose.
• Pain is difficult to manage in patient on buprenorphine since opioid effect will be blunted, buprenorphine is potent partial agonist.

• Anisocoria is when pupillary size is assymetric.

• Anisocoria suggests a lesion in the efferent fibers supplying the pupillary sphinter muscles.

• In order to localize the causative lesion, you must first determine which pupil is abnormal, the smaller one or the larger one.

• The smaller pupil is abnormal when the degree of assymetry is more pronounced in darkened settings.

• The larger pupil is abnormal when the degree of assymetry is more pronounced in bright light.

 Quick Pearls for Intubating:

1. When intubating, make sure to use two hands!

• Have the person holding cricoid pressure let up...cricoid pressure many times makes your job more difficult
• You as the intubator then swing your right hand around and manipulate the larynx (left, right, up, down, etc)
• When you get the view you want, have someone take over pressure and then pass the tube
• Using two hands makes your job so much easier

2. Resist the urge to look for cords

• Your job is to get the tube in the airway
• If you can identify the two arytenoid cartilages, you are home free. Aim north of these structures.
• You don't have to see cords to intubate. All you need are the landmarks that identify the entry into the glottis....just pass the tube north!
• I had a case just a few days ago where the only thing we saw were the two arytenoids (covered in blood). No cords were seen, but we passed the tube above (i.e. north) the arytenoids and we were in.

3. Stylet shape is crucial

• Shape your tube with the "straight to cuff" technique
• The tube is straight and then bent 15-20 degrees at the beginning of the cuff
• This shape will prevent the tube from actually obscuring your view and will increase your success.

Show References

 Phentolamine for vasopressor extravasation

I was recently informed of a case from an another institution in which a patient was started on a vasopressor medication via a peripheral IV while attempts at central access where attempted.  The patient unfortunately suffered permanent extremity ischemia due to significant extravasation of the vasopressor medication into the soft tissue.

• Phentolamine is reportedly the antidote for vasopressor extravasation into the skin and soft tissues (the evidence is not robust and limited primarily to case reports and animal data)
• Phentolamine is a non-specific alpha-blocking agent that inhibits vasoconstriction and theoretically improves blood flow through the affected area
• Take 5-15 mg of phentolamine and mix in 10 mL of normal saline - inject this into the affected area as soon as possible
• Give the patient concurrent IVFs in the event of some systemic absorption

The longitudinal subcostal view on bedside ultrasound can be very helpful at addressing a patient's fluid status. 
Take a look at the diameter of the IVC 2 cm proximal to the hepatic vein on this view and ask the patient to quickly sniff. If the patient has normal fluid status, the diameter of the IVC will collapse approximately 50%.

If you notice that the IVC completely collapses during the sniff, the finding is highly accurate at predicting hypovolemia and a low CVP.

If, on the other hand, the IVC doesn't appear to collapse much at all, the finding is highly accurate at predicting a high CVP and elevated right atrial pressure. This may occur in the presence of fluid overload from decompensated CHF, cardiac tamponade, and conditions associated with RV failure (e.g. massive pulmonary embolism).

Splinting Pearls:

1. When using plaster of paris remember to use at least 10 layers for upper extremities and 15-20 layers for lower extremities.
2. Always apply the splint so that the joint above and below the fracture is immobilized.
3. On radius and ulnar fractures, a sugar tong splint will provide better immobilzation as it also prevents supination/pronation where a posterior long arm or volar splint only prevent flexion and extension.
4. Remember to make sure that the hand is placed in the position of function.
5. Though not required a stockinette provides an additional layer of skin protection and helps to make the ends of the splint looking cleaner.  It can also help hold the splint in place as you ace wrap it.
6. Finally, make sure that you document neurovascular status pre and post splint placement and if any manipulation is done you should have a follow up xray taken to ensure alignment is satisfactory.

Bladder ultrasound increases catheterization success in pediatric patients

• Next time before you attemt to catheterize a child under 36 months measure the transverse bladder diameter with the ultrasound first. 
• If it is > 2 cm you are much more likely to be successful in obtaining the specimen on the first attempt. 
• 94% when ultrasound measurement was used versus 68% patients who had conventional catheterization.

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 A recent landmark article has cited a connection between non-insulin dependent diabetes and low-level arsenic in our drinking water.

• Approximately 13 million in the USA are drinking water that contains Arsenic levels higher than EPA allowable standards
• This study controlled for organic arsenic (found in seafood) and was looking for the effect of inorganic arsenic which is the more toxic compound - don't have to stop eating sushi
• This study essentially found a dose response curve with people with lower arsenic levels having lower incidence of non-insulin dependent diabetes, those with higher levels, higher risk.

Show References

 Navas-Acien A, Silbergeld EK, Pastor-Barriuso R, Guallar E.

 

Arsenic exposure and prevalence of type 2 diabetes in US adults.

JAMA. 2008 Aug 20;300(7):814-22.

• Most studies suggest that the risk of aneurysm rupture significantly increases after the size of 7 mm.

• The risk of rupture is greater for posterior circulation aneurysms.

• Five-year risk of aneurysmal rupture based on size (for anterior and posterior circulation aneurysms, respectively):
  
  ---  7 to 12 mm --> 2.6 and 14.5%              

             ---- 13 to 24 mm --> 14.5 and 18.4%

Complications of Subarachnoid Hemorrhage

The three dreaded complications of SAH include the following:

• Rebleeding
• Hydrocephalus-occurs in as many as 33-50% of patients with SAH. Intraventricular blood (in 20% of cases) acutely occludes the foramen of Monroe and Luschka and obstructs CSF outflow. This is treated by inserting a ventriculostomy catheter. 
• Vasospasm-Usually develops several days after the initial SAH. May be an asymptomatic angiographic phenomenon or cause cerebral ischemia-an important cause of morbidity after SAH. Prophylactic administration of Nimodipine improved outcomes. 

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PEEP in Nonhypoxemic Respiratory Failure

• Patients with ALI/ARDS typically receive PEEP to improve oxygenation
• Patients without ALI/ARDS, however, receive PEEP less frequently (some recent reports indicate that < 50% of these patients receive PEEP)
• A recent study by Spanish investigators found that the use of PEEP (5 - 8 cm H₂0) in nonhypoxemic patients decreased the incidence of ventilator-associated pneumonia and decreased the number of patients who developed hypoxemia
• Interestingly, no differences were found in hospital mortality, duration of mechanical ventilation, or ICU LOS
• Take Home Point: In nonhyoxemic intubated patients, the addition of 5-8 cm H₂0 of PEEP is a reasonable practice and may be beneficial in preventing VAP (pending further study)

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The apical 4-chamber view of the heart on bedside ultrasound gives an excellent comparative view of the sizes of the right ventricle (RV) and left ventricle (LV). The RV is normally ~ 0.5-0.6 the size of the LV. When the RV appears too large, certainly if the RV > LV in size, it indicates RV dilatation.

RV dilatation can be chronic (e.g. COPD or sleep apnea with pulmonary hypertension, etc.) or acute (e.g. PE, RV MI). How can you tell whether the condition is chronic or acute? Just take a look at the RV free wall. If the RV free wall measures < 5 mm, it's a pretty good indication that you are dealing with an acute condition. Think PE or RV MI!

[thanks to Dr. Jim Hwang from Brigham and Women's Hospital for providing this pearl]

Olecranon Bursitis is inflammation and swelling of the bursa overlying the olecranon process of the ulna.  Can result from trauma, overuse, or infection. 

Treatment can consist of:

• Aspiration:  Can be done to rule out infection [send gram stain, culture, and cell count], and be therapeutic by removing the excess fluid.
• NSAIDs
• Local injection of corticosteroids into the bursa
• Wearing of a neopryne elbow sleeve, or ace wraps to provide compression over the bursa and may help prevent reaccumulation of the fluid.

Remember aspiration has some major risks that need to be explained to the paitent:

• Infection may be introduced during the aspiration.  [Follow aseptic techniques and ensure that the skin is adequately prepped with chlorhexidine or betadiene].
• Formation of fistula tract with chronic drainage. [Use a Z or zigzap approach to minimize this complication.]
• Ulnar nerve injury.  Avoided by using a posterior lateral approach and avoiding a medial approach.

They also need to know that the fluid will likely reaccumulate.  So aspiration is not a guaranteed cure. 

In the rush of adrenaline that goes hand in hand with a pediatric intubation often the ETT tip can sometimes be coming out of the little guys toes after passing successfully through the vocal cords, so remember once you get it in and confirm with end-title CO2 detection (capnography or on a monitor) always remember:

Depth of insertion (cm at lip) = 3 x  normal size of ETT

Start at this depth, auscultate bilaterally in the axilla to listen for equal breath sounds, and look for equal chest rise.  If all are good then secure tube and get your chest xray. 

• Cerebral aneurysms are usually not congenital, but rather often form over days, weeks, or months.  

• It is hypothesized that the critical size for rupture is smaller for newly formed aneuryms; thus, treat newly discovered aneurysms that were previously radiographically absent more proactively and cautiously.

• While hypertension and cigarette smoking are not thought to cause aneurysmal rupture, they do contribute to the problem;  Hypertensive smokers are at a 15-fold increased risk of SAH compared to non-hypertensive non-smokers.