Potassium metabolism... enough to make you go Bananas!

Potassium metabolism is one of those things we just have to know. We can really hurt people if get this one wrong. Here is a review on the topic. Now, go a eat some bananas ! The plasma potassium level is normally maintained within narrow limits (typically, 3.5 to 5.0 mmol per liter) by multiple mechanisms that collectively make up potassium homeostasis. Such strict regulation is essential for a broad array of vital physiologic processes. The importance of potassium homeostasis is underscored by the well-recognized finding that patients with hypokalemia or hyperkalemia have an increased rate of death from any cause. In addition, derangements of potassium homeostasis have been associated with pathophysiologic processes, such as progression of cardiac and kidney disease and interstitial fibrosis. External potassium homeostasis regulates renal potassium excretion to balance potassium intake, minus extrarenal potassium loss and correction for any potassium deficits. External potassium balance involves three control systems. Two systems can be categorized as “reactive,” whereas a third system is considered to be “predictive.” A negative-feedback system reacts to changes in the plasma potassium level and regulates the potassium balance. Potassium excretion increases in response to increases in the plasma potassium level, leading to a decrease in the plasma level. A reactive feed-forward system that responds to potassium intake in a manner that is independent of changes in the systemic plasma potassium level has also been recognized. A predictive system appears to modulate the effect of reactive systems, enhancing physiologic mechanisms at the time of day when food intake characteristically occurs — typically, during the day in humans and at night in nocturnal rodents. This predictive system is driven by a circadian oscillator in the suprachiasmatic nucleus of the brain and is entrained to the ambient light–dark cycle. The central oscillator (clock) entrains intracellular clocks in the kidney that generate the cyclic changes in excretion. When food intake is evenly distributed over 24 hours, and physical activity and ambient light are held constant, this system produces a cyclic variation in potassium excretion. Internal potassium homeostasis is the maintenance of an asymmetric distribution of total body potassium between the intracellular and extracellular fluid (approximately 98% intracellular and only a small fraction, approximately 2%, extracellular), which occurs by the balance of active cellular uptake by sodium–potassium adenosine triphosphatase, an enzyme that pumps sodium out of cells while pumping potassium into cells (called the sodium–potassium pump rate), and passive potassium efflux (called the leak rate). Little increase in the plasma potassium level occurs during potassium absorption from the gut in normal persons owing to potassium excretion by the kidney and potassium sequestration by the liver and muscle. Insulin, catecholamines, and mineralocorticoids stimulate potassium uptake into muscle and other tissues. Between meals, the plasma potassium level is nearly constant, as potassium excretion is balanced by the release of sequestered intracellular potassium. The healthy kidney has a robust capacity to excrete potassium, and under normal conditions, most persons can ingest very large quantities of potassium (400 mmol per day or more) without clinically significant hyperkalemia. Potassium that is filtered at the glomerulus is largely reabsorbed in the proximal tubule and the loop of Henle. Consequently, the rate of renal potassium excretion is determined mainly by the difference between potassium secretion and potassium reabsorption in the cortical distal nephron and collecting duct. Both of these processes are regulated — potassium ingestion stimulates potassium secretion and inhibits potassium reabsorption. Factors that regulate potassium secretion and reabsorption can be divided into those that serve to preserve potassium balance (homeostatic) and those that affect potassium excretion without intrinsically acting to preserve potassium balance (contra-homeostatic). Examples of the latter include flow rate in the renal tubular lumen and the luminal sodium level. The acid–base balance also affects potassium excretion. The predominant effect of acidosis is to inhibit potassium clearance, whereas the predominant effect of alkalosis is to stimulate potassium clearance. In vertebrates, a central clock in the suprachiasmatic nucleus of the brain and peripheral clocks that are present in virtually all cells regulate circadian rhythms. Among the many physiologic functions in humans that show circadian rhythms, few are more consistent and stable than the circadian rhythm of urinary potassium excretion. The timing signals from the central clock to the peripheral clocks remain uncertain, but adrenal corticosteroids and agents from other loci have been proposed or identified. Although the action of cortisol in promoting potassium excretion would suggest a direct (nonclock) hormonal effect, studies by Moore-Ede and colleagues indicate that cortisol serves as a clock synchronizer. Aldosterone also affects certain circadian clocks and, in particular, acutely induces the expression of period circadian clock 1 (PER1) in the kidney. Having a basic understanding of the metabolism of this mineral is important when deciding therapies to treat or prevent potassium plasma level variations. Now you know... be careful when writing for potassium or telling patients to take supplements.

PID is not just an STD, get help from your GYN.

Yes, we do see pelvic pain in the ED (a lot of them), and pelvic inflammatory disease is not an uncommon cause of many of those cases. PID is an infection-induced inflammation of the female upper reproductive tract (the endometrium, fallopian tubes, ovaries, or pelvic peritoneum). Many women have clinically silent spread of infection to the upper genital tract, which results in subclinical pelvic inflammatory disease. Pelvic inflammatory disease is a major concern because it can result in long-term reproductive disability, including infertility, ectopic pregnancy, and chronic pelvic pain.

More than 85% of infections are due to sexually transmitted cervical pathogens or bacterial vaginosis–associated microbes, and approximately 15% are due to respiratory or enteric organisms that have colonized the lower genital tract. Ascending infection from the cervix is often due to sexually acquired infections with Neisseria gonorrhoeae or Chlamydia trachomatis. Acute pelvic inflammatory disease has classically been defined by the abrupt onset of severe lower abdominal pain during or shortly after menses, although it is now well recognized that both the onset and severity of symptoms can be more ill-defined and subtle. Atypical, milder clinical manifestations have become more common as rates of N. gonorrhoeae infection have fallen. The symptoms associated with acute pelvic inflammatory disease include pelvic or lower abdominal pain of varying severity, abnormal vaginal discharge, intermenstrual or postcoital bleeding, dyspareunia, and dysuria. Fever can occur, but systemic manifestations are not a prominent feature of pelvic inflammatory disease.

The clinical diagnosis of pelvic inflammatory disease is based on the finding of pelvic organ tenderness, as indicated by cervical motion tenderness, adnexal tenderness, or uterine compression tenderness on bimanual examination, in conjunction with signs of lower genital tract inflammation. Signs of lower genital tract inflammation include cervical mucopus, which is visible as an exudate from the endocervix or as yellow or green mucous on a cotton-tipped swab placed gently into the cervical os (positive “swab test”); cervical friability (easily induced columnar epithelial bleeding); or increased numbers of white cells observed on saline microscopic examination of vaginal secretions (wet mount). All patients with suspected pelvic inflammatory disease should undergo cervical or vaginal nucleic acid amplification tests for N. gonorrhoeae and C. trachomatis infection; if the results are positive, the probability that pelvic inflammatory disease is present increases substantially. Transvaginal ultrasonography and magnetic resonance imaging (MRI) revealing thickened, fluid-filled tubes are timely and highly specific for salpingitis. However, the sensitivity of ultrasonography is only fair, and although MRI has high sensitivity, it is expensive and not typically available in resource-poor settings. Power Doppler studies showing increased fallopian-tube blood flow are highly suggestive of infection.

Most patients are successfully treated as outpatients with single-dose intramuscular ceftriaxone, cefoxitin plus probenicid, or another third-generation cephalosporin (cefotaxime or ceftizoxime), followed by oral doxycycline with or without metronidazole for 2 weeks. For hospitalized patients, therapy with cefotetan or cefoxitin (administered parenterally until 24 to 48 hours after clinical improvement) together with doxycycline and followed by doxycycline with or without metronidazole to complete 2 weeks of treatment is recommended. An alternative regimen of clindamycin and an aminoglycoside may be particularly appropriate for patients with a tubo-ovarian abscess. Adjunctive nonsteroidal anti-inflammatory drugs do not improve the clinical outcome. Removal of an intrauterine device (IUD) does not hasten clinical resolution (and may delay it), and in most cases the IUD is left in place.

Although more than 90% of patients with pelvic inflammatory disease will have a clinical response to CDC-recommended treatment, the long-term outcome of treatment is still suboptimal. It remains unclear why the long-term outcome of treated pelvic inflammatory disease remains so dismal, given the high rates of clinical response. Perhaps infection-induced damage to the fallopian tubes has occurred by the time treatment is first given. This observation, together with the frequent occurrence of subclinical pelvic inflammatory disease, have highlighted the importance of recognizing prevention of pelvic inflammatory disease as a major public heath priority. The U.S. Preventive Services Task Force, CDC, and other professional organizations recommend annual C. trachomatis screening for all sexually active women younger than 25 years of age and older women at increased risk for infection (e.g., women with multiple or new sex partners). These groups also recommend testing for N. gonorrhoeae among women at increased risk for infection (e.g., women with multiple sex partners or previous gonorrhea infection and women living in communities with a high prevalence of disease).

Oxygen IS a drug, use it with caution, only when is needed.

This is a quick review on the potentially harmful effects of too much oxygen, published in this month's EPM magazine. 

THE POTENTIAL HARM OF OXYGEN THERAPY IN MEDICAL EMERGENCIES
Cornet, A.D., et al, Crit Care 17(2):313, April 18, 2013
These Dutch authors comment on possible harm from routine use of supplemental oxygen in patients with a medical emergency. Several early studies reported high-flow oxygen in myocardial infarction patients was associated with reduced cardiac output and stroke volume with an increase in systemic vascular resistance and arterial blood pressure, largely due to vasoconstriction, with no evidence of a benefit of hyperoxia on myocardial ischemia. Clinical trials of supplemental oxygen in patients with cardiac emergencies are limited, but a 2010 Cochrane review reported increased mortality in MI patients receiving supplemental oxygen (RR 3.0). Experimental evidence also suggests an adverse hemodynamic effect of oxygen in patients with congestive heart failure. The adverse effects of supplemental oxygen are more widely appreciated in patients with chronic obstructive pulmonary disease (COPD), and a recent randomized trial noted decreased mortality in COPD patients receiving titrated rather than high-concentration oxygen. 

Hyperoxia in stroke has been noted to be associated with a decrease in cerebral blood flow and increased mortality, and use of supplemental oxygen for most ischemic stroke patients is not supported in American Stroke Association guidelines. Several large studies reported increased mortality and poor neurologic outcomes in hyperoxic patients after resuscitation from cardiac arrest. Although it is possible that vasoconstriction due to hyperoxia might be beneficial in patients with shock, no studies have demonstrated a benefit of supranormal oxygen levels in this setting. The authors advise caution with the routine use of supplemental oxygen for medical emergencies. While hypoxemia should be treated promptly, they recommend slow stepwise titration and feel that an oxygen saturation of 90-94% may be reasonable. 61 references (cornet@vumc.nl – no reprints)

Conclusions:
- Oxygen IS toxic when used in high concentrations and for prolonged periods of time.
- Hyperoxia causes cellular dysfunction 
- Use it only when patient is hypoxic and when hypoxia has been corrected, titrate down to maintain normoxia.
- Share the knowledge and stop the ritual of putting every patient on oxygen !

Emergency Contraception.. the only "REAL" emergency!

You: Hi.. I am Dr X, what can I do for you today?

Patient: Uhhh... my boyfriend and I were... uhhh, you know... (silence)

You: Yes...

Patient: My boyfriend and I were having sex and... (silence)

You: Uh-hu....

Patient: You know, he didn't pull out on time. (in soft voice)

Boyfriend: I told you do move, but you didn't move! (Obviously angry)

Patient: Shut up! Do you think I want to be here?

You: It's OK, no need to argue. You want to make sure you don't get pregnant, correct?

Patient: YES !! That's right doc. You gotta help me. I am going to school, work 2 jobs, my mom is going to kill me and .... and....

You get the idea!

Emergency contraception is one of those issues that sound simple, but it is not. Matching the right method to the right patient requires some understanding of the pharmacology of these agents and also knowing more about your patient's history. Here is a review from this months, NEJM. Enjoy!

Oral emergency contraceptive pills are the most commonly used form of emergency contraception. Two regimens are currently marketed in the United States: ulipristal acetate (30 mg) and levonorgestrel (1.5 mg). In 39 clinical trials that included a combined total of more than 18,000 women, rates of pregnancy after use of one of these two regimens ranged from 0 to 6.5%. Interpretation of these numbers is problematic because the likelihood of pregnancy in the absence of emergency contraception was not directly assessed; estimates that were based on the days of the menstrual cycle on which the participants had sex suggest that use of each of these regimens reduces the risk of pregnancy after a single sex act by 40 to 90%. In the United States, products containing 1.5 mg of levonorgestrel in one tablet may legally be sold over the counter to women and men of all ages. Although the ulipristal regimen was recently approved for nonprescription sale in Europe, it still requires a prescription in the United States; consequently, use of this regimen in the United States is limited. Some but not all data suggest reduced efficacy of the levonorgestrel regimen in obese women with BMI’s as low as 25. If you think about it, it is not that much!

The levonorgestrel regimen is effective for at least 4 or 5 days after sex but may be more effective the sooner it is taken; data on the ulipristal regimen have not indicated a decrease in efficacy through 120 hours after sex. However, since both regimens work largely by delaying or inhibiting ovulation, and since women are usually unaware of whether ovulation is imminent, prompt use is prudent. Neither of these two oral emergency contraceptive regimens has any recognized contraindications.

The most effective form of emergency contraception is the copper IUD. A review of 42 studies showed that, of 7034 women who received IUDs up to 10 days after unprotected sex, only 0.09% subsequently became pregnant. Recent analyses suggest that the IUD is effective for emergency contraception throughout the menstrual cycle and can be inserted at any point if pregnancy is ruled out. A key advantage of the IUD over oral emergency contraceptive pills is that the IUD can provide ongoing contraception for at least 10 years. Almost all women can safely use an IUD for emergency contraception; the only recognized contraindications are pregnancy, cancer of the genital tract, uterine malformation preventing device placement, copper allergy, mucopurulent cervicitis, current pelvic inflammatory disease, and known current cervical infection with chlamydia or gonorrhea. These conditions can be reasonably ruled out on the basis of interview, examination, and, if indicated, pregnancy test; routine testing for cervical infection is not necessary.

No deaths or serious complications have been causally linked to either oral emergency contraception regimen. Previous studies over the past decades have not revealed adverse effects of levonorgestrel exposure during pregnancy on either the woman or the conceptus. Data on ulipristal exposure during pregnancy are limited, but combined data from postmarketing surveillance and clinical trials showed that among 232 pregnancies with a known outcome in which the woman and conceptus were exposed to ulipristal, no teratogenic effects were seen. The incidence of pelvic inflammatory disease after IUD insertion is less than 5% even when the device is inserted through an infected cervix; whether IUD insertion itself increases this incidence has not been definitively established. IUD insertion can be uncomfortable, and some women have vaginal bleeding and cramping after insertion. In the one published study of IUD insertion for emergency contraception, which was conducted in community clinics, the IUD insertion attempt was unsuccessful in 18% of women; this proportion is higher than that reported in clinical trials of IUD insertion for routine contraception.

Key points:

- IDU is the king of emergency contraception. However, not for all women.

- Oral hormonal options, mainly levonogestrel and ulipristal, have failure rates that vary from 0-6%.

- Women with higher BMI's are at risk for failure of the oral forms.

- The sooner you take them, the better.

- It is good to have a plan C and D, when B doesn't work.

Sciatica... The Pain That Keeps Coming Back !

I don't need to tell anyone reading this, that back pain is coming, recurrent, misunderstood and mistreated. The term "sciatica" is loosely used for any back pain that radiates, which is technically not right, but because the sciatic nerve roots are the most commonly affected, it is by chance correct most of the times.

Although sciatica has several causes, Mixter and Barr extended previous observations to establish in 1934 that the principal source is compression of a lumbar nerve root by disk material that has ruptured through its surrounding annulus. Neuroradiologic studies affirm that 85% of cases of sciatica are associated with disk disorder. The fourth and fifth lumbar nerve roots and the first two sacral nerve roots join in the lumbosacral plexus to form the peroneal and tibial nerves that leave the pelvis in an ensheathed single trunk as the sciatic nerve, the largest nerve in the body. Disturbances anywhere along its course can give rise to sciatica, but the most common areas are at the sites of disk rupture and osteoarthritic change — at the L4–L5 and L5–S1 levels and, less frequently, the L3–L4 level — where there is generally compression of the root below the corresponding disk.

Many clinical tests have been devised to determine whether sciatic pain is caused by disk compression of a spinal nerve root; most of the tests are variations of the straight-leg-raising test. In a patient in the supine position, raising the leg with the knee extended stretches the nerve root over the protruded disk and results in a nocifensive response of muscle contraction. A positive sign consists of reproduction or marked worsening of the patient’s initial pain and firm resistance to further elevation of the leg. A diagnosis of disk compression is likely if pain radiates from the buttock to below the knee when the angle of the leg is between 30 and 70 degrees. Sensitivity of the test for disk herniation is approximately 90%, but specificity is low. Many persons without spinal abnormalities have hamstring and gluteal tightness with discomfort elicited by straight-leg raising, but the pain is more diffuse than in sciatica and the leg can be lifted higher if the maneuver is performed slowly. Increased pain on dorsiflexion of the foot or large toe increases sensitivity. The crossed straight-leg-raising test (Fajersztajn’s test) for sciatic pain involves raising the unaffected leg; this test is 90% specific for disk herniation on the contralateral side but is insensitive

The most common initial treatment is pain control by means of medication and physical therapy. Activity is usually self-limited in proportion to the degree of discomfort, and although rest is often recommended, it is not better than movement in patients who are able to remain active. Nonsteroidal antiinflammatory medications may provide short-term relief for low back and sciatic pain; however, it is difficult to determine their effect on sciatica, and many patients report little relief. Orally or systemically administered glucocorticoids have been used to ameliorate sciatica, but it is difficult to interpret their effect. Guidelines recommend restrictions on the use of opioids. Antiepileptic drugs, antidepressant agents (e.g., tricyclic agents), muscle relaxants, and pain medications that enhance the activity of γ-aminobutyric acid have been used but with little supporting data. The benefits of physical therapy and various exercise regimens are difficult to determine, and the superiority of any one program has not been established, although most appear to be safe. Spinal manipulation for sciatica is widely used and has been studied with an assortment of designs and comparators; therefore, reviews of existing trials, most considered of low or moderate quality, draw limited conclusions. Epidural injections of glucocorticoids are frequently administered for low back pain and related conditions. Trials have suggested an associated short-term decrease in leg pain but no decrease in the need for subsequent surgery.

Most trials comparing surgical treatment and conservative treatment of sciatica due to lumbar disk disease favor surgery, because it results in earlier relief of pain. A review of major trials with adequate data for analysis concluded that there was conflicting evidence on long-term benefit but that surgery relieved pain more rapidly and to a greater degree than did conservative therapy. North American Spine Society guidelines state that diskectomy provides more effective and more rapid symptom relief than do other treatments for symptoms that warrant surgery, although less severe symptoms can be managed conservatively. Complications of surgery are infrequent but include dural tears with leakage of cerebrospinal fluid, as well as damage to the root or cauda equina.

In summary

- Mechanical back pain is common, and sciatica is only one cause of back pain.

- L4-5 are most commonly affected, and the passive straight leg test is very sensitive (although poorly specific) in the diagnosis.

- Activity as tolerated, NSAID's, muscle relaxant, steroids, anti-epileptics and anti-depressants all have some evidence to support itheir use, so choose according to side effect profile and patient preference. 
- Oral opiates are effective for short term but discourage for more than a few days.

- Epidural injections are effective for some patient and physiotherapy is good when done properly

- Surgery definitely not for everyone, selected case may benefit from it.

Allergic Rhinitis in the ED... makes a difference !

OK... I know that runny nose, congestion and sneezing is not a sexy EM topic. However, we often see these patients in the ED complaining of "sinus infections" and not infrequently, get inappropriate prescriptions for antibiotics when what they need is a nasal steroid. Patients with AR are also likely to suffer asthma and atopic dermatitis. So let's review the basics on this topic and how they related to other common problems seen in the emergency department.

The presence of allergic rhinitis (seasonal or perennial) significantly increases the probability of asthma: up to 40% of people with allergic rhinitis have or will have asthma. Atopic eczema frequently precedes allergic rhinitis. Patients with allergic rhinitis usually have allergic conjunctivitis as well. The factors determining which atopic disease will develop in an individual person and the reasons why some people have only rhinitis and others have rhinitis after eczema or with asthma remain unclear.

The differential diagnosis includes forms of rhinitis that are nonallergic in origin such as a noninflammatory rhinopathy (also known as vasomotor rhinitis) and nonallergic chronic rhinosinusitis. Seasonal symptoms can be caused by viral infections, especially if the patient is a child or lives with children; rhinovirus has a marked peak in incidence in September and a smaller peak in the spring. The diagnosis of allergic rhinitis is often made clinically on the basis of characteristic symptoms and a good response to empirical treatment with an antihistamine or nasal glucocorticoid. Formal diagnosis is based on evidence of sensitization, measured either by the presence of allergen-specific IgE in the serum or by positive epicutaneous skin tests (i.e., wheal and flare responses to allergen extracts) and a history of symptoms that correspond with exposure to the sensitizing allergen. Epicutaneous skin testing and testing for allergen-specific IgE have similar sensitivity, although they do not identify sensitization in an entirely overlapping group of patients.

Pharmacologic treatment options include H₁-antihistamines, intranasal glucocorticoids, and leukotriene-receptor antagonists. Therapy usually starts with oral antihistamines, frequently initiated by the patient. H₁-antihistamines are also available as nasal sprays by prescription. The intranasal preparations appear to be similar to oral preparations in efficacy but may be less acceptable to patients owing to a bitter taste. The effect of antihistamines on symptoms, especially nasal congestion, is modest. They can be combined with oral decongestants, and the combination can improve nasal airflow in the short term (on the basis of data from trials lasting 2 to 6 weeks), at the cost of some side effects. Topical nasal decongestants are more effective than oral agents, but there are reports of rebound congestion (rhinitis medicamentosa) or reduced effectiveness beginning as early as 3 days after treatment, and only short-term use is recommended. In one study, adding an intranasal glucocorticoid reversed the reduced effectiveness of a topical decongestant. Intranasal glucocorticoids are the most effective pharmacotherapy for seasonal allergic rhinitis, yet the overall efficacy is moderate. Although the clinical effects appear within a day, the peak effect in cases of perennial rhinitis is not reached for several weeks. The superiority of intranasal glucocorticoids over antihistamines in the treatment of perennial allergic rhinitis is uncertain. The effect of leukotriene-receptor antagonists on the symptoms of allergic rhinitis is similar to or slightly less than that of oral antihistamines, and some randomized trials have shown a benefit of adding the leukotriene-receptor antagonist montelukast to an antihistamine. Although the majority of trials have favored intranasal glucocorticoids over this combination, data are inconsistent; this combination should be considered for patients whose symptoms are inadequately controlled with an antihistamine and who do not wish to use a glucocorticoid nasal spray. There is no significant benefit of adding an oral antihistamine or montelukast to a nasal glucocorticoid. However, in randomized trials, the combination of an intranasal antihistamine plus an intranasal glucocorticoid has been shown to be superior to either agent alone.

Although allergen immunotherapy has traditionally been administered subcutaneously in the United States, rapidly dissolving tablets for sublingual administration were recently approved by the FDA for treatment of grass and ragweed allergy. With immunotherapy, unlike pharmacotherapy, the effect persists after the discontinuation of therapy. If there is improvement in the first year, injections are generally continued for at least 3 years. Data from randomized trials are lacking to guide decisions about the duration of therapy. Subcutaneous immunotherapy carries a risk of systemic reactions, which occur in 0.1% of injection visits, in rare cases leading to life-threatening anaphylaxis (1 reaction per 1 million injection visits). Although subcutaneous immunotherapy has not been compared with sublingual immunotherapy in large head-to-head trials, indirect comparisons suggest that subcutaneous immunotherapy is more effective for symptom relief. However, sublingual immunotherapy has a clear advantage in terms of safety, with very few reports of anaphylactic reactions. In summary: - Treat allergic rhinitis aggressively. Oral H1 antihistaminics +/- nasal steroids is a good first line approach. - Oral or topical decongestants help to alleviate symptoms, but with some side effects and risk of tachyphylaxis and rebound effect. Therefore, use with caution and for short periods of time. - Refer to allergy testing patient with severe symptoms, combination with asthma and/or atopic dermatitis.