What are schizonts and hypnozoites? What types of malaria produce them?
Ans:
Schizonts are multinucleated stages of parasites that undergo mitotic division within white cells and are produced by all forms of malaria. Hypnozoites are specialized dormant forms of the malaria parasite within the liver and are produced only by two types of malaria, P. vivax and P. ovale. Hypnozoites reactivate spontaneously weeks or many months after the initial exposure to infective mosquitoes; their release into the blood-stream results in late-onset or relapsing clinical disease. Primaquine is the only available drug that acts on the hypnozoites of P. vivax and P. ovale in the liver.
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New England Journal of Medicine - Vol. 359, No. 6, August 7, 2008
2008年8月7日 星期四
Malaria prophylaxis for pregnant woman
What types of malaria chemoprophylaxis would be safe for a pregnant woman?
Ans:
Malaria is more severe in pregnancy, and the risks of adverse outcomes (for both the mother and the fetus) are increased. No chemoprophylactic agent is 100% effective. The WHO and the CDC both recommend that pregnant women not travel to areas where malaria is endemic. Most women refrain from traveling to these areas during pregnancy, but for pregnant women who decide to travel or must travel, mefloquine is the drug of choice for chloroquine-resistant malaria. (Chloroquine can also be used during pregnancy.)
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New England Journal of Medicine - Vol. 359, No. 6, August 7, 2008
Ans:
Malaria is more severe in pregnancy, and the risks of adverse outcomes (for both the mother and the fetus) are increased. No chemoprophylactic agent is 100% effective. The WHO and the CDC both recommend that pregnant women not travel to areas where malaria is endemic. Most women refrain from traveling to these areas during pregnancy, but for pregnant women who decide to travel or must travel, mefloquine is the drug of choice for chloroquine-resistant malaria. (Chloroquine can also be used during pregnancy.)
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New England Journal of Medicine - Vol. 359, No. 6, August 7, 2008
Chloroquine Resistance
The resistance of P. falciparum to chloroquine is nearly universal; chloroquine remains effective only in Mexico, areas of Central America that are west of the Panama Canal, the Caribbean, East Asia, and a few Middle Eastern countries. In all other areas where malaria is endemic, atovaquone–proguanil, mefloquine, or doxycycline is recommended by the CDC and WHO. Primary prophylaxis with chloroquine when appropriate and a choice of atovaquone–proguanil, mefloquine, or doxycycline for other areas according to traveler circumstances is recommended by these organizations.
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New England Journal of Medicine - Vol. 359, No. 6, August 7, 2008
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New England Journal of Medicine - Vol. 359, No. 6, August 7, 2008
Malaria Symptoms
Malaria in travelers is usually characterized by fever and influenza-like symptoms, including headache and back pain. Vomiting, diarrhea, abdominal cramping, and cough may occur and may be confused with symptoms associated with more common infections. Textbooks often describe the fever as occurring in discrete episodes lasting a few hours every 2 to 3 days; however, in travelers the fever usually has an irregular pattern throughout the day. Disease caused by P. falciparum in travelers most often occurs 9 to 14 days after an infectious bite, but it may occur up to months later, especially in patients who have received suboptimal prophylaxis.
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New England Journal of Medicine - Vol. 359, No. 6, August 7, 2008
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New England Journal of Medicine - Vol. 359, No. 6, August 7, 2008
2008年8月1日 星期五
Lumbar Puncture 後之頭痛
Lumbar Puncture and Post-Dural Puncture Headaches: Implications for the Emergency Physician
Volume 35, Issue 2, August 2008, Pages 149-157
Conclusions
Dural puncture procedures are commonly performed by various medical practitioners, including emergency physicians, for many reasons. Post-dural puncture headache (PDPH) is a relatively common complication. The degree of pain and disability caused by PDPHs is considerable. Appropriate use of smaller gauge, atraumatic needles is likely the single most important factor in reducing PDPH. Hydration and bed rest do little to prevent PDPH. Treatment of mild, nondebilitating headaches usually can be accomplished with limited activity, analgesics, and methylxanthine therapy until they resolve spontaneously. For more severe headaches, methylxanthine derivatives may be tried with epidural blood patch (EBP) as a first-line alternative or to be used if methylxanthines fail. It is helpful to use 24-gauge Sprotte spinal needles in all patients at risk for PDPH. For patients who have moderate to severe pain, cannot or do not want to remain on bed rest, and those in whom narcotic pain medication is not a practical treatment option, EBP is an appropriate first-line therapy. In general, EBP is safe, well tolerated and effective. Though the technique for epidural blood patch is not significantly more difficult than lumbar puncture, it is a procedure most commonly performed by anesthesiologists.
Volume 35, Issue 2, August 2008, Pages 149-157
Conclusions
Dural puncture procedures are commonly performed by various medical practitioners, including emergency physicians, for many reasons. Post-dural puncture headache (PDPH) is a relatively common complication. The degree of pain and disability caused by PDPHs is considerable. Appropriate use of smaller gauge, atraumatic needles is likely the single most important factor in reducing PDPH. Hydration and bed rest do little to prevent PDPH. Treatment of mild, nondebilitating headaches usually can be accomplished with limited activity, analgesics, and methylxanthine therapy until they resolve spontaneously. For more severe headaches, methylxanthine derivatives may be tried with epidural blood patch (EBP) as a first-line alternative or to be used if methylxanthines fail. It is helpful to use 24-gauge Sprotte spinal needles in all patients at risk for PDPH. For patients who have moderate to severe pain, cannot or do not want to remain on bed rest, and those in whom narcotic pain medication is not a practical treatment option, EBP is an appropriate first-line therapy. In general, EBP is safe, well tolerated and effective. Though the technique for epidural blood patch is not significantly more difficult than lumbar puncture, it is a procedure most commonly performed by anesthesiologists.
Bystander CPR 的重要性
Out-of-Hospital Unwitnessed Cardiopulmonary Collapse and No-Bystander CPR: A Practical Addition to Resuscitation Termination Guidelines
Journal of Emergency Medicine Volume 35, Issue 2, August 2008, Pages 175-179
AbstractCardiopulmonary resuscitation (CPR) provides possible survival from otherwise fatal cardiopulmonary collapse. Termination guidelines have been developed for use when resuscitation has no potential benefit for a victim. The purpose of this prospective cohort study was to determine if unwitnessed collapse combined with no-bystander cardiopulmonary resuscitation would support a decision to terminate attempted resuscitation. There were 541 patients analyzed during 6 months, with functional neurological survival the outcome of interest. There were no functional neurological survivors at hospital discharge among the 180 victims in the unwitnessed, no-bystander CPR subgroup (95% confidence interval [CI] 0.0%–2.1%). Functional neurological survival for witnessed collapse, bystander CPR was 6.0% (95% CI 2.8%–12.5%), for witnessed collapse, no-bystander CPR was 3.8% (95% CI 1.9%–7.7%), and for unwitnessed collapse, bystander CPR 1.3% (95% CI 0.2%–6.9%). With confirmation by further studies, unwitnessed collapse and lack of bystander CPR may be a practical addition to resuscitation termination guidelines.
Journal of Emergency Medicine Volume 35, Issue 2, August 2008, Pages 175-179
AbstractCardiopulmonary resuscitation (CPR) provides possible survival from otherwise fatal cardiopulmonary collapse. Termination guidelines have been developed for use when resuscitation has no potential benefit for a victim. The purpose of this prospective cohort study was to determine if unwitnessed collapse combined with no-bystander cardiopulmonary resuscitation would support a decision to terminate attempted resuscitation. There were 541 patients analyzed during 6 months, with functional neurological survival the outcome of interest. There were no functional neurological survivors at hospital discharge among the 180 victims in the unwitnessed, no-bystander CPR subgroup (95% confidence interval [CI] 0.0%–2.1%). Functional neurological survival for witnessed collapse, bystander CPR was 6.0% (95% CI 2.8%–12.5%), for witnessed collapse, no-bystander CPR was 3.8% (95% CI 1.9%–7.7%), and for unwitnessed collapse, bystander CPR 1.3% (95% CI 0.2%–6.9%). With confirmation by further studies, unwitnessed collapse and lack of bystander CPR may be a practical addition to resuscitation termination guidelines.
牛源聚合血紅蛋白 - HBOC-201
HBOC-201: A Viable Alternative to Blood Transfusion
Use of hemoglobin-based oxygen carrier-201 avoided need for blood transfusion in nearly 60% of patients.
Despite strategies to conserve use of packed red blood cells (PRBCs), experts predict that availability will not meet the increasing demand by an aging population. Hemoglobin-based oxygen carrier-201 (HBOC-201) is a bovine–hemoglobin-based blood substitute that is approved in South Africa for clinical use. In a randomized, single-blind, controlled, multinational study, researchers (some of whom were affiliated with the manufacturer) assessed whether administration of HBOC-201 eliminates the need for PRBC transfusion in adult patients undergoing orthopedic surgery.
Overall, 688 patients (mean age, 61) with hemoglobin concentrations <10.5>7 mL/kg within 2 hours, oliguria, and significant weakness or dizziness. Patients in the HBOC group received a loading dose of 65 g of hemoglobin infused in 500 mL (a volume considered equivalent to 1 unit of PRBCs); additional doses were administered for up to 6 days to a maximum of 325 g (2500 mL), after which need for additional oxygen-carrying capacity was met by transfusion of PRBCs.
Overall, 59% of patients in the HBOC group did not require PRBC transfusion. The HBOC group had significantly higher rates of adverse events (e.g., elevated blood pressure) than the PRBC group (8.5 vs. 5.9 per patient) and serious adverse events (e.g., cardiac events and strokes; 0.34 vs. 0.25 per patient). Findings of a safety analysis led the authors to conclude that risk for adverse events from HBOC was greatest in patients who were older than 80, had volume overload, and were undertreated.
Comment: HBOC-201 does not require crossmatching and can be stored at room temperature for as long as 3 years. In this study, its use eliminated the need for transfusion of allogeneic PRBCs in 59% of patients. Its safety profile was inferior to that of PRBC transfusion, including a greater incidence of acute coronary syndromes and strokes, which the authors partially attributed to age older than 80, volume overload, and undertreatment. Overall, the authors suggest that patients younger than 80 with moderate clinical need for transfusion can be managed with up to 10 units of HBOC-201, thereby preserving the stockpile of PRBCs for other patients.
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John A. Marx, MD, FAAEM, FACEP
Published in Journal Watch Emergency Medicine August 1, 2008
Citation(s): Jahr JS et al. HBOC-201 as an alternative to blood transfusion: Efficacy and safety evaluation in a multicenter phase III trial in elective orthopedic surgery. J Trauma 2008 Jun; 64:1484.
http://www.hemopure.co.za/index.php
Use of hemoglobin-based oxygen carrier-201 avoided need for blood transfusion in nearly 60% of patients.
Despite strategies to conserve use of packed red blood cells (PRBCs), experts predict that availability will not meet the increasing demand by an aging population. Hemoglobin-based oxygen carrier-201 (HBOC-201) is a bovine–hemoglobin-based blood substitute that is approved in South Africa for clinical use. In a randomized, single-blind, controlled, multinational study, researchers (some of whom were affiliated with the manufacturer) assessed whether administration of HBOC-201 eliminates the need for PRBC transfusion in adult patients undergoing orthopedic surgery.
Overall, 688 patients (mean age, 61) with hemoglobin concentrations <10.5>7 mL/kg within 2 hours, oliguria, and significant weakness or dizziness. Patients in the HBOC group received a loading dose of 65 g of hemoglobin infused in 500 mL (a volume considered equivalent to 1 unit of PRBCs); additional doses were administered for up to 6 days to a maximum of 325 g (2500 mL), after which need for additional oxygen-carrying capacity was met by transfusion of PRBCs.
Overall, 59% of patients in the HBOC group did not require PRBC transfusion. The HBOC group had significantly higher rates of adverse events (e.g., elevated blood pressure) than the PRBC group (8.5 vs. 5.9 per patient) and serious adverse events (e.g., cardiac events and strokes; 0.34 vs. 0.25 per patient). Findings of a safety analysis led the authors to conclude that risk for adverse events from HBOC was greatest in patients who were older than 80, had volume overload, and were undertreated.
Comment: HBOC-201 does not require crossmatching and can be stored at room temperature for as long as 3 years. In this study, its use eliminated the need for transfusion of allogeneic PRBCs in 59% of patients. Its safety profile was inferior to that of PRBC transfusion, including a greater incidence of acute coronary syndromes and strokes, which the authors partially attributed to age older than 80, volume overload, and undertreatment. Overall, the authors suggest that patients younger than 80 with moderate clinical need for transfusion can be managed with up to 10 units of HBOC-201, thereby preserving the stockpile of PRBCs for other patients.
—
John A. Marx, MD, FAAEM, FACEP
Published in Journal Watch Emergency Medicine August 1, 2008
Citation(s): Jahr JS et al. HBOC-201 as an alternative to blood transfusion: Efficacy and safety evaluation in a multicenter phase III trial in elective orthopedic surgery. J Trauma 2008 Jun; 64:1484.
http://www.hemopure.co.za/index.php
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