Pharmacokinetics: The extent of percutaneous absorption of topical corticosteroids is determined by many factors including the vehicle and the integrity of the epidermal barrier. Occlusive dressings with hydrocortisone for up to 24 hours have not been demonstrated to increase penetration; however, occlusion of hydrocortisone for 96 hours markedly enhances penetration. Topical corticosteroids can be absorbed from normal intact skin. Inflammation and/or other disease processes in the skin may increase percutaneous absorption.
The caudal approach to the epidural space involves the use of a Tuohy needle, an intravenous catheter, or a hypodermic needle to puncture the sacrococcygeal membrane . Injecting local anaesthetic at this level can result in analgesia and/or anaesthesia of the perineum and groin areas. The caudal epidural technique is often used in infants and children undergoing surgery involving the groin, pelvis or lower extremities. In this population, caudal epidural analgesia is usually combined with general anaesthesia since most children do not tolerate surgery when regional anaesthesia is employed as the sole modality.
Low-potency steroids (Class 6 and 7) ( Table 1 ) are preferred for use in infants and for the face, neck, axilla, and diaper regions. Moderate-potency (Class 5) steroids may be needed for severe conditions; they should be limited to short courses for use on the trunk and extremities. Twice-daily dosing is appropriate in most situations, although once-daily application in the morning often is sufficient to obtain an adequate clinical response. 122 Parents should be shown the appropriate amount per dose using the concept of a fingertip unit . One fingertip unit is the amount of topical steroid expressed from a 5-mm diameter nozzle, applied from the distal skin crease to the tip of the index finger (approximately 500 mg). 137 This amount is sufficient to cover an area of skin the size of 2 adult palms.