Episode 2: Urologic Emergencies

Episode 2 – Urologic Emergencies (iTunes) 

The Free Open Access Medical Education (FOAM) – The Skeptics Guide to Emergency Medicine (SGEM) Episode 71

The podcast reviews: Tamsulosin for ureteral stones: a systematic review and meta-analysis of a randomized controlled trial.

  • Paper’s Conclusion:  ‘Tamsulosin is a safe and effective medical expulsive therapy choice for ureteral stones. It should be recommended for most patients with distal ureteral stones before stones are 10 mm in size. In the future, high-quality multicenter, randomized and placebo- controlled trials are needed to evaluate the outcome.”

The SGEM’s analysis:  Tamsulosin is useless in most ED patients with ureteral colic unless their stone size exceeds at least 4mm.

The Bread and Butter

We summarize some key topics from the following readings,  Tintinalli (7e) Chapters 95, 97; Rosen’s (8e) Chapter 99, but the point isn’t to just take our word for it.  Go enrich your fundamental understanding yourself!

Renal Colic

Diagnostics

  • Urinalysis demonstrating microscopic hematuria.  Note: 10-15% of patients with renal colic have no hematuria
  • Imaging isn’t needed in patient’s with a history of renal colic and symptoms consistent with their previous episodes and without signs of symptoms of significant obstruction or infection.  Non-contrast CT scan is currently the standard diagnostic imaging of choice and bedside ultrasound may be used to look for hydronephrosis, but isn’t great for picking up stones.  The Ultrasound Podcast guys have a great episode on the topic.  Plain films (KUBs) are only useful in following the location of the stone after CT scan.
  • Make sure you’re not dealing with a tricky abdominal aortic aneurysm.

Management

  • Analgesics – nonsteroidals and, if needed, narcotics
  • Anti-emetics
  • Use of alpha-antagonist such as tamsulosin is controversial, as indicated in The SGEM podcast.  Tintinalli supports the use of these agents, whereas Rosen’s cautions that use of this medication is controversial.
  • Disposition – home with a strainer to catch the stone and outpatient urology follow up if patient has adequate pain control and oral intake and lacks significant infection or obstruction.  Remember, stones <5mm are going to pass on their own most of the time (~95%), whereas patients with stones >8mm will undergo intervention 95% of the time.

Infected Kidney Stones – Suspect in patients with SIRS criteria or those that appear sick (don’t forget that temperature <36 C, 10% bands, <4K white blood cells, and elevated respiratory rate are all part of SIRS) and in those with signs of infection on their urinalysis.

Management

  • Urgent or emergent urologic consultation to evaluate the need for drainage and for relief of the obstruction.
  • Treat sepsis and shock with good sepsis care including antibiotics and fluid resuscitation but these patients may need immediate operative intervention by urology for adequate source control.  This may include a stent or percutaneous nephrostomy tube.  Call urology.

Acute Urinary Retention

Causes

  • Spontaneous – Benign Prostatic Hypertrophy (BPH)
  • Precipitated – a host of medications (pseudoephedrine, NSAIDs, anticholinergics), anesthesia, strictures, masses, spinal cord compression (most sensitive finding in cauda equina!), infection

Diagnosis

  • Palpate the patient’s abdomen, feel for a distended bladder
  • Ultrasound, checking for a post-void residual >150 cc (LxWxH x 0.52 – although, notably there are a variety of coefficients to multiply by based on the shape)
  • Check a urinalysis, BUN, creatinine
  • History and physical should guide further testing with regard to etiology

Management

  • Treat the underlying cause (stop the offending medication, treat the infection, etc)
  • Place a foley catheter to relieve the obstruction.  There is some literature on spontaneous voiding trials in the ED but this isn’t standard (see this Academic Life in Emergency Medicine article).
  • Urology follow up within 3-7 days
  • Admit patients with signs of sepsis, co-morbidities, or renal insufficiency (or those that won’t follow up otherwise).

Generously donated Rosh Review questions (scroll for answers)

Question 1 [polldaddy poll=8057572]

Question 2 [polldaddy poll=8077276]

Listen 

 

Answers:

1) C.  The 3 primary predictors of stone passage without the need for surgical intervention are stone size, stone location, and the degree of patient pain at discharge. The most important factor, however, is calculus size. Approximately 90% of calculi smaller than 5 mm pass spontaneously within 4 weeks.

2) A.  Indications for hospitalization: intractable nausea/vomiting, severe dehydration, pain, associated UTI, solitary or transplanted kidney, high grade obstruction.

References:

Tintinalli (8e) Chapter 97.  Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 7e. 2011.

Ban KM, Easter JS.  Selected Urologic Problems.  Chapter 99.  Rosen’s Emergency Medicine.  (8e) p 1326-1354

Yen D, Lee C. Chapter 95. Acute Urinary Retention. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 7e. 2011.

Episode #1: EMCrit Episode #122 – Cyanide and Carbon Monoxide Toxicity

Welcome

Welcome to FOAMcast, a podcast created by residents who love Free Open Access Medical education (FOAM).  We are looking at cutting edge FOAM and distilling it down to the basics.  We’re not doing this to replace reading and hard work but increase interest and direct listeners to linking sexy FOAM with core content.  So listen, and go read it yourself.

What Did Weingart and Dr. Nelson say?

  • Patient in extremis or arrest after a fire and burn size doesn’t correlate to severity of illness?  Treat for cyanide toxicity.
  • Treatment: hydroxocobalamin 5g IV in ~250mL normal saline in adults or 70 mg/kg in pediatric patients.
  • Get labs, including lactate, carboxyhemoglobin level, and transaminases prior to giving hydroxocobalamin if possible because the drug turns everything red and interferes with these tests.

And the Basics of Chemical Asphyxiants?

If a patient presents after smoke exposure, consider cyanide and carbon monoxide toxicity (Case Quiz).  These toxicities have many similarities such as: impaired oxygen delivery and utilization, metabolic acidosis with elevated lactate, and presence in patients with smoke inhalation.

Cyanide Toxicity – Tintinalli (7e) Ch 198; Rosen’s (8e) Ch 179

Mechanism – Binds to the iron of the cytochrome a3 of complex IV in the mitochondria, the last step of oxidative phosphorylation, effectively shutting down the mitochondria and ATP production leading to tissue hypoperfusion.

Diagnostics-

  • Cyanide level is worthless in the acute setting.  If suspicious, treat without waiting for labs.
  • Labs often demonstrate a metabolic acidosis and, in a fire victim, a lactate >10 mmol/L is suspicious for cyanide toxicity.

Treatment –

  • ABCs – 100% oxygen, crystalloids and vasopressors for hypotension
  • Hydroxocobalamin 5 g IV for adults or 70 mg/kg IV for pediatrics
    • Cyanide binds to hydroxocobalamin, forming cyanocobalamin (vitamin B12) which is renally excreted.  It also turns everything red, which can interfere with labs and dialysis.
    • Note: Tintinalli cautions that there’s no good evidence on hydroxocobalamin over the traditional sodium nitrite kits.
  • There’s also the traditional cyanide antidotes which include: inhaled amyl nitrite, Sodium nitrite 3% – 300 mg IV (10 mL), and sodium thiosulfate.
    •  Sodium nitrite forms methemoglobin from hemoglobin, for which cyanide has enormous affinity.  Cyanide leaves the cytochrome, setting the mitochondria free, forming cyanmethemoglobin. This is transformed to thiocyanate by an enzyme (rhodanese) and renally excreted. 
    • If using this approach in a patient with carbon monoxide poisoning, use only sodium thiosulfate given these patient already have impaired tissue oxygenation and methemoglobinemia only further exacerbates this.

Carbon Monoxide (CO) – Tintinalli (7e) Ch 217; Rosen’s (8e) Ch 159

Carbon monoxide poisoning is non-specific and may manifest as headache, flu like illness, or coma and death and occurs throughout the year, not just during heat/generator seasons.

Mechanism –

  • Most well recognized – CO has a far greater affinity for hemoglobin than oxygen, leading to impaired delivery of oxygen to tissues.
  • Causes a left shift of the hemoglobin-oxygen dissociation curve (Right shift = Removal of oxygen from hemoglobin.  Left shift = loaded hemoglobin).
  • Inhibits the cytochrome system in aerobic metabolism, akin to cyanide toxicity, leading to a shift toward anaerobic metabolism.

Diagnostics –

  • Clinical suspicion is key.
  • Labs may show a metabolic acidosis with elevated lactate.
  • Carboxyhemoglobin level is often available and for boards, remember that levels >15% in pregnant patients or >25% in other patients may be a trigger to think about hyperbaric oxygen therapy.  These levels do not correlate with symptoms.

Treatment –

  • ABCs, including high inspired oxygen which reduces the half-life of CO from ~4 hrs to 90 minutes.
  • Hyperbaric oxygen (HBO) or “diving” patients in controversial but if a patient is near-dead, pregnant with significant toxicity (level >15), consider HBO, at least on the boards.

Questions generously donated by the Rosh Review

Question 1.  [polldaddy poll=8074537]

 

Question 2. [polldaddy poll=8074535]

 

Episode 1: Cyanide and Carbon Monoxide Toxicity

(iTunes)

References:

Gresham C, LoVecchio F.  Chapter 198.  Inhaled Toxins. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 7e. New York, NY: McGraw-Hill; 2011. p 1317-1320.

Nelson RS, Hoffman RS.  Chapter 159.  Inhaled Toxins.  Rosen’s Emergency Medicine, 8e.  2014.  p 2036-2043.

Maloney G. Chapter 217. Carbon Monoxide.  Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 7e. New York, NY: McGraw-Hill; 2011. p 1410-1413.

 

Answers.  1) A  2)A