Experts on Call Answers to your questions from our medical experts ß-blockers and allergy injections Are ß-blockers contraindicated in patients undergoing allergy injection? ? Submitted by: Beth Vallieres, MD, Cambridge, Ontario Patients with asthma are at higher risk for inhibitors may also be problematic during adverse reactions to immunotherapy com - anaphylaxis, as the blockade of ACE pared to rhinitis, particularly if not well con - inhibitors prevents the compensatory trolled. Additional risk factors that have been release of angiotensin, a potent vasoncon - identified in patients experiencing fatal reac - stricto©r during hypotension, whicth isoassoci - ht ribu tions are: ig ated with anaphyilasxist. Theraefdo,re, immuno- r D wnlo • dosage errors, py therapiyashlould ncedrotainly be avoided in o rc rs ca use • first injection from aCnew vial of extract epatientussreequiringonß-abllockers and perhaps m ised ers and om thorACE blofcokrinpg agents as well. C . Au opy • use of ß-blocking agoentrs. 1 ited le c e ohib sing al pr t a Reference The probleSm stems unsoet from apnriinncreased for rised and 1. Reid MJ, Lockey RF, Turkeltaub PC, et al: Survey of fatalities from trisk of aunthaollergic rveiaecwtion or anaphylaxis skin testing and immunotherapy 1985-1989. J Allergy Clin o Una lay, N from the dinisjepction, but from the difficulty Immunol 1993; 92(1 Pt 1):6-15. in treating such a reaction, as these patients can be very resistant to standard regimens. Similarly, angiotensin converting enzyme (ACE) Answered by: Dr. Tom Gerstner Contraindicated treatments in sleep apnea and CHF Are there any treatments that are contraindicated in patients with both sleep ? apnea and CHF? Submitted by: Louis G. Latulippe, MD, Cap-Rouge, Quebec Obstructive sleep apnea (OSA) is a risk fac - hospitalization rates and survival). 2 Use of tor for increased morbidity and mortality other medical therapies for CHF, including from cardiovascular conditions, such as angiotensin converting enzyme inhibitors, hypertension. 1 Central sleep apnea (CSA) is angiotensin receptor blockers, ß-blockers, present in approximately 25% to 40% of diuretics and digoxin, are not contraindicat - patients with congestive heart failure (CHF). 2 ed in the setting of coexistent sleep apnea. Although small improvements are seen in References physiological parameters ( e.g. , ejection frac - 1. Flemons WW: Obstructive sleep apnea. NEJM 2002; 347(7):498- tion, apnea-hypopnea index), treatment with 504. 2. Bradley TD, Logan AG, Kimoff RJ, et al: Continuous positive air - continuous positive airway pressure for way pressure for central sleep apnea and heart failure. NEJM combined CSA and CHF has not been 2005; 353(19):2025-33. shown to improve or worsen important clinical endpoints ( e.g. , quality of life, Answered by: Dr. Paul Hernandez 24 The Canadian Journal of Diagnosis / July 2007 Experts on Call Overcoming chronic insomnia How is chronic insomnia treated? ? Submitted by: Man Wai Kwan, MD, Vancouver, British Columbia As a first step, psychiatric disorders, including effective dose. Because many patients with chronic depression and generalized anxiety conditioned insomnia have developed poor disorders, should be ruled out as possible sleep habits, improving sleep hygiene is usu - cause for chronic insomnia, or properly treat - ally beneficial. ed if present. In the absence of any psychi - Stimulus-control therapy is recommended atric disorders, chronic insomia may imply a to break the conditioning and improve the psychophysiological insomnia that is often association between going to bed and being referred to as a conditioned insomnia. That able to fall asleep. Its rules attempt to means the patient has developed a condi - enhance stimulus cues for sleeping and tioned arousal associated with attempts to diminish associations with sleeplessness. The sleep. Objects associated with sleep ( e.g. , bed, following instructions are simple, but they bedroom) likewise become conditioned stim - must be followed consistently. uli that evoke insomnia. The condition occurs The first step is to go to bed only when in combination with other causes of insomnia, sleepy, to maximize success. The second including episodes of tension due to family step is to use the bed only for sleeping. While and/or work-related stress. In contrast to the in bed, do not watch television, do not read, insomnia in patients with psychiatric disor - do not eat and do not talk on the telephone. ders, daytime adaptation is generally good. The third step is to instruct the patient not to Work and relationships are satisfying; howev - lie in bed and become frustrated if unable to er, extreme tiredness can exist. Other features sleep. After a few minutes (without watching include: the clock), patients are to get up, go to anoth - • excessive worry about not being able to er room and do something non-arousing until sleep, sleepiness returns. The goal is to associate • trying too hard to sleep, the bed with rapid sleep onset. The last two • rumination, inability to clear one’s mind steps attempt to enhance the mechanisms while trying to sleep, underlying the circadian and sleep-wake • increased muscle tension when cycles. Step four is to awaken at the same attempting to sleep, time every morning, regardless of bedtime, • being able to sleep better when away total sleep time, or day of week. Step five is to from one’s own bedroom and totally avoid napping. • being able to fall asleep when not trying Stimulus control therapy does work; (e.g. , watching television). results take weeks to months to appear. If The sleep complaint becomes fixed over these instructions are continually practiced, time. Interestingly, many patients with condi - the bouts of insomnia lessen in both fre - tioned insomnia sleep well in the laboratory. quency and severity. Treatment is difficult. Sleeping pills should Answered by: be used only sparingly and at the lowest Dr. Hany Bissada 26 The Canadian Journal of Diagnosis / July 2007 Experts on Call Dealing with GI stromal tumours What are the treatment options for metastatic GIST? ? Submitted by: Sheila Fergusson, MD, Kelowna, British Columbia GI stromal tumours (GISTs) are rare, constitut - and sustained responses in > 50% of patients ing approximately 1% of all GI cancers. The with stable disease. Another 30% of patients management of patients with unresectable, had sustained responses lasting more than locally-advanced or metastatic GISTs has five years. changed dramatically over the past five years, Patients who are intolerant of imatinib or prior to which no effective therapy existed. who become refractory to imatinib may be Now, patients with advanced GIST should be candidates for treatment with sunitinib, anoth - referred to medical oncology. The majority of er multitargeted tyrosine kinase inhibitor. GISTs have mutations in the KIT protoonco - gene. Imatinib, an orally active tyrosine kinase inhibitor of c-KIT, has demonstrated dramatic Answered by: Dr. Sharlene Gill Do finasteride or selenium prevent prostate cancer? Is there any evidence that the use of finasteride or selenium prevents prostate ? cancer? Submitted by: Peter T. C. Lee, MD, New Glasgow , Nova Scotia Selenium is an important constituent of many The use of finasteride in the chemopre - antioxidant enzymes. It can be found in vention of prostate was studied in the grains, fish, meat, poultry, eggs and dairy Prostate Cancer Prevention Trial (PCPT). 2 In products and enters the food chain through the PCPT, 18,882 men ≥ 55-years-of-age plant consumption. The Nutritional Prevention with normal findings on digital rectal exami - of Cancer (NCP) trial, a randomized study of nation and a PSA level of ≤ 3.0 ng/mL were oral selenized yeast in patients with non - randomly assigned to treatment with finas - melanoma skin cancer, 1 showed the strongest teride ( i.e. , 5 mg q.d.) or placebo for seven evidence for a protective effect of selenium. In years. This trial showed that the prevalence that trial, 1,312 participants took the equiva - of prostate cancer was reduced by 24.8%, lent of 200 g of yeast q.d. vs. placebo with a from 24.4% to 18.4%, in those randomized mean followµ-up of 4.5 years. The incidence of to finasteride compared with placebo. prostate cancer was reduced in the selenium However, the results of this study are still arm by two-thirds compared with placebo. being debated. Currently, the SELenium and vitamin E Cancer prevention Trial (SELECT) is being done to see For resources, please contact [email protected] if prostate cancer can be prevented by seleni - um supplementation. Answered by: Dr. Hugues Widmer The Canadian Journal of Diagnosis / July 2007 27 Experts on Call Combining allergy serums I noticed that some allergists combine different allergy serums into one needle for ? injection ( i.e. , moulds and pollen). Is this acceptable practice? Submitted by: Roshan Dheda, MD, Bradford, Ontario In general, allergen immunotherapy (IT) has allergen extracts may result in allergen been shown to be more successful in degradation due to proteases that are pre - patients with a single sensitivity and far less sent. In particular, mixing mould with pollen effective in those with multiple allergies. The extracts may reduce pollen allergen potency. efficacy of IT is strongly related to an ade - I would suggest that one carefully chooses quate dose of allergen which can then the most relevant one or two allergens, induce the immunologic changes necessary based on the patient’s history and ensure for acquisition of tolerance. All too often, that adequate doses are used. doses are inadequate for this to occur, espe - Resource cially in the context of multiple extracts in a 1. Nelson HS, Ikle D, Buchmeier A: Studies of allergen extract stabil - single vial. Mixing of various allergen extracts ity: The effects of dilution and mixing. J Allergy Clin Immunol 1996; 98(2):382-8. may dilute the allergen concentration to a suboptimal dose. Also, the mixing of various Answered by: Dr.