New content quiz December 2013

The pronator fat pad is a small fat plane over the volar aspect of the distal forearm which is visible in about 90% of normal lateral radiographs as a thin radiolucency running parallel to the distal radius with the distal edge in contact with the volar aspect of the radius. The sensitivity and specificity of a positive fat pad sign for fractures in this region based on MRI studies are both about 70%. Previous studies reported much better test characteristics than this, however did not use MRI as the gold standard. (link)

The presence of 2 or more of the risk factors is associated with a 25% rate of antibiotic resistance to standard therapy compared to a 2% incidence in patients with 0-1 risk factor. (link)

Platelet levels are usually highest between 1 and 6 months of age with the normal range being between  275 and 600 X 10-9/L. (link)

Normally the arterial [HCO3-] in children < 2 years of age is 2 mmol/L lower than in adults. The normal range is 17– 24 mmol/L in neonates and 19 – 24 mmol/L in children 2 months – 2 years of age. (link)

The normal range of the base deficit is -3 to +3 mmol/L in adults,  –10 to –2 mmol/L in neonates and  –7 to –1 mmol/L in infants. (link)

HbF is normally about 50 – 85% of total Hb at birth, 15% at 1 year of age, < 5% at 2 years of age and < 2% after 2 years of age. (link)

Resolution occurs in 80% with adrenaline following aspiration but is unlike to be successful if priapism present > 36 hours. Phenylephrine is about 65% successful however does not have the beta adrenergic effects of adrenaline. Metaraminol may also be used, but is only about 40% effective. Ischaemic priapism is considered present if a cavernosal blood gas demonstrates a pH < 7.25, pO2 < 30 or pCO2 > 60. (link)

Insertion length in adults on the right side = (height(cm)/10) cm, and on the left side = (height(cm)/10) + 4 cm. The insertion length in infants on the right side = (height(cm)/16) cm and on the left side = (height(cm)/14) cm. (link)

Pregnancy duration is classified as follows: early term: 37 – 38 weeks, 6 days; full term: 39 – 40 weeks, 6 days; late term: 41 – 41 weeks, 6 days; post term: ≥ 42 weeks. (link)

Fentanyl is the only agent listed that is dosed based on actual body weight. (link)

Commonly used antihistamines have the following ratings: chlorpheniramine and cyproheptadine category A; loratadine category B1; fexofenadine category B2; promethazine category C. (link)

Mumps orchitis occurs in 15 – 30% of postpubertal males with mumps, with onset usually 4-5 days after the onset of parotitis. It is unilateral in approximately 70% (hence bilateral in up to 30%) of cases with bilateral cases developing in the opposite testicle 3-4 days after the first testicle is involved. It may occur without parotitis and presents with chills, sweats, headache and backache, swinging temperature and severe local testicular pain and tenderness. The scrotum may be very swollen and oedematous and the testes are often impalpable. Reduced fertility following orchitis is rare, even when bilateral. (link)

Dengue shock syndrome usually develops 3-5 days after onset of fever, and occurs in less than 5% of cases of Dengue overall, and even less frequently than that in travellers. It is rarely associated with platelet counts low enough to cause bleeding on their own, however haemorrhage can occur as a result of vascular leakage and low platelet counts. The second rash of Dengue that spreads from the extremities to the trunk may occur at the same time as shock, but is not diagnostic of Dengue shock syndrome. (link)

The oculocephalic reflex (also known as “doll’s eye” movements) is the involuntary movement of the eyes with head movement. A positive reflex is when the eyes of the patient remain stationary while the head is moved, in either a side to side or up and down motion. It does not require object fixation to be present as it occurs in unconscious patients who are blind or in the dark. It is absent in conscious patients as it is suppressed by cortical inputs. It indicates an intact brainstem and suggests a non structural cause for coma. An absent reflex occurs in: hysterical coma; lesions of the labyrinth, vestibular nerve; lesions of cranial nerves III, IV or VI; lesions of the extra-ocular muscles (very rare);  lesions of the connecting pathways of the pons or medulla; lesions of the neck proprioceptors. (link)

Structures that normally enhance following IV contrast include: the dura (although usually not recognised when next to the skull due to similar levels of attenuation); the falx and tentorium; the choroid plexus; the vessels in the circle of Willis. The pineal gland is commonly calcified, but does not normally enhance. (link)