Parathyroid imaging: comparison of double-tracer (T1-201, Tc-99m) scintigraphy and high-resolution US

Parathyroid scintigraphy using a double-tracer (T1-201, Tc-99m) subtraction technique depicted 17 of 23 (74%) parathyroid adenomas in patients with and without previous neck operations. High-resolution (10-MHz) ultrasound (US) depicted 18 (78%) of these adenomas. Average tumor size depicted by US was 17 X 10 X 8 mm (excluding a giant adenoma) and 19 X 10 X 9 mm by scintigraphy. Alone, neither modality was particularly sensitive in the depiction of primary hyperplasia of the parathyroid glands, but combined techniques were more effective than the use of a single modality. With both US and T1-201 scintigraphy, only two of 23 cases of parathyroid adenoma in the neck were missed, and none of the eight cases of secondary hyperplasia were missed. In 11 patients who had previously undergone neck surgery, parathyroid tumors were identified in eight by either US or double-tracer scintigraphy. Preoperative parathyroid imaging with double-tracer scintigraphy and high-resolution US is suggested for patients with hyperparathyroidism, particularly in those patients who have had previous parathyroid surgery.     

Postnatal development of opioid regulation of micturition in the kitten.

Endogenous opioids tonically regulate micturition in adult mammals. The present study sought to determine if opioids regulate micturition in neonatal kittens. Naloxone (up to 2 mg/kg given i.p. or i.v. to unanesthetized/ketamine-anesthetized or chloralose-anesthetized kittens, respectively), an opioid receptor antagonist, produced no effects in unanesthetized, ketamine-anesthetized, or chloralose-anesthetized kittens that had been prepared for bladder pressure recording, until 3 weeks of age. This indicates that endogenous opioids are not tonically regulating micturition in neonatal kittens. From 3 weeks up to at least 6 weeks of age, naloxone (100 micrograms/kg i.p. or i.v.) weakly facilitated bladder activity by transiently increasing the amplitude and/or duration of bladder contractions, but no effects on frequency of contractions was recorded. Morphine (up to 2 mg/kg given i.p. or i.v. to unanesthetized/ketamine-anesthetized or chloralose-anesthetized kittens, respectively), an opioid agonist, did not inhibit bladder contractions in unanesthetized or ketamine-anesthetized neonatal kittens, but it did inhibit (at a threshold dose of 100 micrograms/kg) and completely abolished (at a dose of 300 micrograms/kg) bladder activity in chloralose-anesthetized kittens in a dose-dependent, naloxone-reversible manner. Surprisingly, following morphine administration to unanesthetized or ketamine-anesthetized neonatal kittens, naloxone now produced an adult-like enhancement of bladder activity. These latter results indicate that opioid receptors, whose inhibitory effects are anesthetic-dependent, are present along the micturition reflex pathway in neonates. Immunohistochemical studies of the sacral spinal cord revealed that opioid peptides are distributed similarly in neonatal and adult cats.     

Superparamagnetic iron oxide-enhanced MR imaging: pulse sequence optimization for detection of liver cancer

The effects of magnetic resonance (MR) pulse sequences and timing parameters on tumor-liver contrast were studied in an animal model of metastatic liver cancer. Six spin-echo (SE), three inversion-recovery (IR), and four gradient-echo (GRE) sequences were evaluated at 0.6 T before and after injection of super-paramagnetic iron oxide. GRE techniques, irrespective of echo time and flip angle, showed the greatest change in signal intensity (enhancement) of the liver after administration of iron oxide. Single-acquisition GRE sequences (16 seconds) matched the contrast-to-noise ratio (C/N) performance of the most effective 6.4-minute SE sequences. Multiexcitation GRE sequences showed tumor-liver C/Ns per unit time that were significantly (P less than .05) higher than those achieved with SE and IR sequences. GRE sequences, which recruit intravoxel dephasing as an additional source of transverse relaxation enhancement (T2*), show a higher C/N per unit time and in this respect seem superior to SE and IR sequences for MR imaging with superparamagnetic iron oxide.     

Methylphenidate poisoning: an evidence-based consensus guideline for out-of-hospital management

A review of US poison center data for 2004 showed over 8,000 ingestions of methylphenidate. A guideline that determines the conditions for emergency department referral and prehospital care could potentially optimize patient outcome, avoid unnecessary emergency department visits, reduce health care costs, and reduce life disruption for patients and caregivers. An evidence-based expert consensus process was used to create the guideline. Relevant articles were abstracted by a trained physician researcher. The first draft of the guideline was created by the lead author. The entire panel discussed and refined the guideline before distribution to secondary reviewers for comment. The panel then made changes based on the secondary review comments. The objective of this guideline is to assist poison center personnel in the appropriate out-of-hospital triage and initial out-of-hospital management of patients with suspected ingestions of methylphenidate by 1) describing the process by which a specialist in poison information should evaluate an exposure to methylphenidate, 2) identifying the key decision elements in managing cases of methylphenidate ingestion, 3) providing clear and practical recommendations that reflect the current state of knowledge, and 4) identifying needs for research. This review focuses on the ingestion of more than a single therapeutic dose of methylphenidate and the effects of an overdose and is based on an assessment of current scientific and clinical information. The expert consensus panel recognizes that specific patient care decisions may be at variance with this guideline and are the prerogative of the patient and the health professionals providing care, considering all of the circumstances involved. This guideline does not substitute for clinical judgment. Recommendations are in chronological order of likely clinical use. The grade of recommendation is in parentheses. 1) All patients with suicidal intent, intentional abuse, or in cases in which a malicious intent is suspected (e.g., child abuse or neglect) should be referred to an emergency department (Grade D). 2) In patients without evidence of self-harm, abuse, or malicious intent, poison center personnel should elicit additional information including the time of the ingestion, the precise dose ingested, and the presence of coingestants (Grade D). 3) Patients who are chronically taking a monoamine oxidase inhibitor and who have ingested any amount of methylphenidate require referral to an emergency department (Grade D). 4) Patients experiencing any changes in behavior other than mild stimulation or agitation should be referred to an emergency department. Examples of moderate to severe symptoms that warrant referral include moderate-to-severe agitation, hallucinations, abnormal muscle movements, headache, chest pain, loss of consciousness, or convulsions (Grade D). 5) For patients referred to an emergency department, transportation via ambulance should be considered based on several factors including the condition of the patient and the length of time it will take for the patient to arrive at the emergency department (Grade D). 6) If the patient has no symptoms, and more than 3 hours have elapsed between the time of ingestion and the call to the poison center, referral to an emergency department is not recommended (Grade D). 7) Patients with acute or acute-on-chronic ingestions of less than a toxic dose (see recommendations 8, 9, and 10) or chronic exposures to methylphenidate with no or mild symptoms can be observed at home with instructions to call the poison center back if symptoms develop or worsen. For acute-on-chronic ingestions, the caller should be instructed not to administer methylphenidate to the patient for the next 24 hours. The poison center should consider making a follow-up call at approximately 3 hours after ingestion (Grade D). 8) Patients who ingest more than 2 mg/kg or 60 mg, whichever is less, of an immediate-release formulation (or the equivalent amount of a modified-release formulation that has been chewed) should be referred to an emergency department (Grade C). 9) If a patch has been swallowed, consider the entire contents of the patch (not just the labeled dose of the patch) to have been ingested. Patients who ingest more than 2 mg/kg or 60 mg, whichever is less should be referred to an emergency department. If it is known that the patch has been chewed only briefly, and the patch remains intact, significant toxicity is unlikely and emergency department referral is not necessary (Grade D). 10) Patients who ingest more than 4 mg/kg or 120 mg, whichever is less, of an intact modified-release formulation should be referred to an emergency department (Grade D). 11) For oral exposures, do not induce emesis (Grade D). 12) Pre-hospital activated charcoal administration, if available, should only be carried out by health professionals and only if no contraindications are present. Do not delay transportation in order to administer activate charcoal (Grade D). 13) Benzodiazepines can be administered by EMS personnel if agitation, dystonia, or convulsions are present and if authorized by EMS medical direction expressed by written treatment protocol or policy or direct medical oversight (Grade C). 14) Standard advanced cardiac life support (ACLS) measures should be administered by EMS personnel if respiratory arrest, cardiac dysrhythmias, or cardiac arrest are present and if authorized by EMS medical direction expressed by written treatment protocol or policy or direct medical oversight (Grade C).     

Iron ingestion: an evidence-based consensus guideline for out-of-hospital management

From 1983 to 1991, iron caused over 30% of the deaths from accidental ingestion of drug products by children. An evidence-based expert consensus process was used to create this guideline. Relevant articles were abstracted by a trained physician researcher. The first draft of the guideline was created by the primary author. The entire panel discussed and refined the guideline before its distribution to secondary reviewers for comment. The panel then made changes in response to comments received. The objective of this guideline is to assist poison center personnel in the appropriate out-of-hospital triage and initial management of patients with suspected ingestions of iron by 1) describing the manner in which an ingestion of iron might be managed, 2) identifying the key decision elements in managing cases of iron ingestion, 3) providing clear and practical recommendations that reflect the current state of knowledge, and 4) identifying needs for research. This guideline applies to ingestion of iron alone and is based on an assessment of current scientific and clinical information. The expert consensus panel recognizes that specific patient care decisions may be at variance with this guideline and are the prerogative of the patient and the health professionals providing care, considering all of the circumstances involved. The panel's recommendations follow; the grade of recommendation is in parentheses. 1) Patients with stated or suspected self-harm or who are victims of malicious administration of an iron product should be referred to an acute care medical facility immediately. This activity should be guided by local poison center procedures. In general, this should occur regardless of the amount ingested (Grade D). 2) Pediatric or adult patients with a known ingestion of 40 mg/kg or greater of elemental iron in the form of adult ferrous salt formulations or who have severe or persistent symptoms related to iron ingestion should be referred to a healthcare facility for medical evaluation. Patients who have ingested less than 40 mg/kg of elemental iron and who are having mild symptoms can be observed at home. Mild symptoms such as vomiting and diarrhea occur frequently. These mild symptoms should not necessarily prompt referral to a healthcare facility. Patients with more serious symptoms, such as persistent vomiting and diarrhea, alterations in level of consciousness, hematemesis, and bloody diarrhea require referral. The same dose threshold should be used for pregnant women, however, when calculating the mg/kg dose ingested, the pre-pregnancy weight of the woman should be used (Grade C). 3) Patients with ingestions of children's chewable vitamins plus iron should be observed at home with appropriate follow-up. The presence of diarrhea should not be the sole indicator for referral as these products are often sweetened with sorbitol. Children may need referral for the management of dehydration if vomiting or diarrhea is severe or prolonged (Grade C). 4) Patients with unintentional ingestions of carbonyl iron or polysaccharide-iron complex formulations should be observed at home with appropriate follow-up (Grade C). 5) Ipecac syrup, activated charcoal, cathartics, or oral complexing agents, such as bicarbonate or phosphate solutions, should not be used in the out-of-hospital management of iron ingestions (Grade C). 6) Asymptomatic patients are unlikely to develop symptoms if the interval between ingestion and the call to the poison center is greater than 6 hours. These patients should not need referral or prolonged observation. Depending on the specific circumstances, follow-up calls might be indicated (Grade C).