Learning Objectives: After reading this article, the physician should be able to:
- Explain why blood cultures are usually not useful in guiding treatment of adult patients with uncomplicated cellulitis.
- Describe why attempting ultra-sound-guided peripheral intravenous access may be superior to blind landmark attempts by a physician in patients with difficult intravenous access.
- Identify the medical problems that may bring renal transplant recipients to the emergency department.
Release Date: October 2008
Are Blood Cultures Necessary in Adults with Cellulitis?
Mills AM, Chen EH
Ann Emerg Med
Should you order blood cultures on patients admitted to the hospital with cellulitis? The authors of this article attempt to answer that question by reviewing the available literature.
Perl et al retrospectively reviewed 757 adult patients admitted from the ED with cellulitis. Blood cultures were obtained on admission in 553 (73%) of these patients. Only 11 of 553 (2%) patients who had blood cultures drawn on admission had a pathogen isolated, not thought to be a contaminant. Of these 11 patients, nine were already on appropriate gram-positive empiric coverage. In the other two cases, empiric coverage based on the clinical presentation covered the atypical organisms that were identified and did not require a change in antimicrobial therapy. No patient in this large cohort required a change in antibiotics based on blood culture results.
Kulthanan et al retrospectively studied 150 patients in Thailand who were admitted with cellulitis. Both blood cultures and skin biopsies were collected. Patients were divided into immunocompetent and immunocompromised groups. Although blood cultures were found to be positive in 21.3 percent of immunocompromised patients and only 8.3 percent of immunocompetent patients, this difference was not statistically significant. The authors concluded that immunocompromised patients were not more likely to have positive blood cultures than immunocompetent patients, that blood cultures were low yield, and that empiric antibiotic choice was sufficient in the absence of culture results.
Lutomski studied 25 nondiabetic patients with cellulitis that had needle aspirations and blood cultures drawn before antibiotics were started. Only 16 percent of patients had positive cultures, all for gram-positive organisms susceptible to empiric antibiotic coverage for Staphylococcus and Streptococcus. The study concluded that patients with localized cellulitis rarely become bacteremic.
Hook enrolled 50 adults with cellulitis, and collected blood cultures and aspirates from the leading edge of the advancing erythema. Only four percent had positive blood cultures, and none of the skin biopsies or aspirates grew a pathogen. One positive patient grew Staphylococcus, and the other grew Streptococcus. Blood cultures and wound cultures were not useful in this small study, and no patients required a change in initial antimicrobial therapy.
Ho et al retrospectively looked at 130 healthy adults admitted for cellulitis, 66 of whom had blood cultures drawn on admission. Only one set was positive and grew Group A Streptococcus.
The bottom line is that the yield of blood cultures in adults with cellulitis is low. Even in the few cases where cultures were positive, none of the patients required a change in antimicrobial therapy. It remains to be seen if blood cultures are required in patients with complicated cellulitis such as diabetics or those with perineum involvement. The authors of this best-evidence review conclude that healthy adults admitted for uncomplicated cellulitis do not require blood cultures in the ED.
Ultrasonography-Guided Peripheral Intravenous Access versus Traditional Approaches in Patients with Difficult Intravenous Access
Constantino TG, et al
Ann Emerg Med
Intravenous access can be difficult in obese patients, IV drug abusers, or those with chronic medical conditions. After failed attempts at peripheral access by nurses, the traditional approach usually involves peripheral attempts by the emergency physician and central venous access if all peripheral attempts fail. This prospective study sought to determine if bedside ultrasonography could facilitate peripheral IV access in difficult patients after failed attempts by nursing staff.
Two university hospitals enrolled 60 patients with difficult IV access defined as three failed attempts by ED nurses. Patients otherwise requiring central venous access and pregnant patients were excluded. Patients were assigned to the study group (n=39) using ultrasound-guided peripheral access or a control group (n=21) using the traditional approach of emergency physician attempts at peripheral access.
In an attempt to prevent unnecessary central access, some control patients were also entered into a “rescue pathway” of ultrasound-guided peripheral attempts after the emergency physician failed three times.
The primary endpoint was successful peripheral venous access. Secondary end-points included complications, patient satisfaction, and time to successful cannulation. The ultrasound group had a greater success rate at cannulation (97%) than the control group (33%). The average total time to access was four minutes in the ultrasound group compared with 15 minutes in the control group. Additionally, the ultrasound group required significantly fewer punctures and reported higher satisfaction rates. Finally, all patients (100%) placed in the rescue pathway (n=11) were “rescued” from unnecessary central access by using ultrasound guidance. There were no significant complications in either group.
The authors acknowledge there was a strong potential for selection bias in that more patients were randomized to the ultrasound group on odd days than to the control group on even days. Even so, they conclude that ultrasound-guided peripheral access in patients with difficult IV access is safe and fast, and has a superior success rate when compared with the traditional approach.
Care of the Renal Transplant Recipient in the Emergency Department
Venkat KK, Venkat A
Ann Emerg Med
Kidney transplant patients are complex and experience a wide variety of complications. Acute and chronic rejection, drug interactions with immunosuppressive regimens, and opportunistic infections are just a few examples of the unfamiliar territory faced by the emergency physician in managing these patients. One fundamental principle in managing any transplant patient is early contact with the patient's transplantation physician.
The transplanted kidney is usually placed in the right lower quadrant. The donor kidney is anastomosed to the ipsilateral iliac artery and vein of the recipient. Renal transplant recipients require lifelong immunosuppression to prevent rejection. Patients are commonly started on “triple therapy” with cyclosporine or tacrolimus, mycophenolate mofetil or azathioprine, and corticosteroids. Months after transplantation, drugs are gradually withdrawn, with steroids commonly discontinued in the first year. As part of maintenance therapy, most patients also now receive anti-lymphocyte antibodies.
Cyclosporine has been associated with hyperkalemia, hyperuricemia/gout, and nephrotoxicity. Tacrolimus can cause nausea and neurologic sequelae such as headaches and seizures. Azathioprine is associated with bone marrow suppression, hepatotoxicity, and pancreatitis. Mycophenolate mofetil can cause gastro-intestinal side effects such as abdominal pain, nausea, vomiting, and gastrointestinal bleeding. Corticosteroids, often given in high doses early after transplantation to prevent acute rejection, commonly cause weight gain and difficult-to-control diabetes. Less common effects of corticosteroids are avascular necrosis of the hip, mood disturbances, and gastrointestinal bleeding.
Any renal or urinary tract disorder that can occur in the native kidneys also can occur in the allograft. Rejection is the only cause of renal failure unique to transplant recipients. ED management of renal failure in transplant patients should be the same for a patient with native kidneys with an attempt to identify and treat pre-renal and post-renal causes.
The two most common causes of renal failure are tacrolimus or cyclosporine toxicity and organ rejection. These are impossible to differentiate in the ED, and often require a renal biopsy. Tacrolimus and cyclosporine levels are useful in this setting because elevated levels make nephrotoxicity more likely than rejection. Classically rejection presents as fever, pain at the allograft site, and increased creatinine, but this is rare in the present era of immunosuppressive regimens. Chronic allograft rejection presents with proteinuria and progressive chronic renal failure. Rejection is treated with high-dose corticosteroids in consultation with a transplant nephrologist.
Renal ultrasonography with Doppler is important in assessing renal failure in transplant patients. Hydronephrosis and obstructive nephropathy is usually treated with percutaneous nephrostomy. Occlusion of the renal artery or vein, which most often occurs in the first post-transplant week, warrants emergent surgical intervention to save the allograft. Urine leak, which usually occurs in the first post-transplant month from a break in the ureteral anastomosis, is treated with Foley catheter placement and surgical repair.
Urinary tract infections may involve the allograft or native kidney or bladder. The presence of leukocytes in the urine does not necessarily indicate infection and may be a presentation of rejection. Pyelonephritis in renal transplant patients is usually treated with two intravenous antibiotics given the immunosuppression of the host.
Fever is a common presentation in the ED in immunosuppressed transplant recipients. In the first month after transplantation, opportunistic infections are uncommon, and the patient is most likely to be febrile from postoperative causes of fever such as pneumonia or atelectasis. Between one month and one year after transplantation, a variety of opportunistic infections are possible. Cytomegalovirus disease occurs in 10 percent to 25 percent of patients, and presents with fever, transaminitis, and leukopenia. In the first post-transplant year, febrile patients are usually hospitalized and undergo a workup for opportunistic infection and rejection. Beyond the first post-transplant year, community-acquired infections are more common than opportunistic infections, and often can be managed without hospital admission.
The risk of cardiovascular disease is increased threefold in kidney transplant recipients. A high index of suspicion is warranted for coronary syndromes because atypical presentations are common. Diltiazem and amiodarone can inhibit cytochrome P-450 mediated metabolism of cyclosporine and tacrolimus, potentially leading to nephrotoxicity.
Patients on immunosuppressants, especially steroids, often have a milder presentation of intra-abdominal emergencies such as appendicitis and a low threshold for CT imaging is warranted. Neurologic complaints in kidney transplant patients should raise the suspicion for CNS infection, lymphoma, or adverse effects of tacrolimus and cyclosporine. Headache warrants a lumbar puncture in immunosuppressed transplant recipients even without classic findings of meningitis.
The most common ED pulmonary presentation in transplant patients is pneumonia. Early stages of infection may not be visible on chest x-ray, and chest CT may be useful to identify infiltrates. Critically ill renal transplant patients presenting to the ED will need stress-dose corticosteroids to prevent adrenal insufficiency unless they have not received steroids in the past six months.
About the LLSA
As part of its continuous certification program, the American Board of Emergency Medicine has developed the Lifelong Learning and Self-Assessment (LLSA) program to promote continuous education of diplomates. Each year, beginning in 2004, 16 to 20 articles are chosen based on the Emergency Medicine Model. A list of these articles can be found on the ABEM web site, www.abem.org.
ABEM is not authorized to confer CME credit for the successful completion of the LLSA test, but it has no objection to physicians participating in such activities. EMN's CME activity, Living with the LLSA, is not affiliated with ABEM's LLSA program, and reading this article and completing the quiz does not count toward ABEM certification. Rather, participants may earn 1 CME credit from the Lippincott Continuing Medical Education Institute, Inc., for each completed EMN quiz.
CME Participation Instructions
To earn CME credit, you must read the article in Emergency Medicine News, and complete the quiz, answering at least 80 percent of the questions correctly. Mail the completed quiz with your check for $10 payable to the Lippincott Continuing Medical Education Institute, Inc., 770 Township Line Road, Suite 300, Yardley, PA 19067. Only the first entry will be considered for credit, and must be received by Lippincott Continuing Medical Education Institute, Inc., by October 31, 2009. Acknowledgement will be sent to you within six to eight weeks of participation.
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