Page 132 - 16Neonatal Jaundice_compressed
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Treatment





                         The GDG therefore considered that there was a compelling need to provide specific guidance to
                         clinicians regarding thresholds for treatment. When  determining the thresholds, the GDG
                         considered that the primary aim was to choose a threshold with a wide margin of safety, with
                         the threshold for phototherapy well below that for exchange transfusion. The rationale for this
                         was the  difference in the safety profile between the two therapies. However, the choice of
                         threshold should not be so low that phototherapy would be used unnecessarily. In choosing the
                         threshold levels, the GDG considered that account should be taken of current common practice
                         while eliminating more extreme threshold strategies.
                         Phototherapy thresholds for infants of 38 weeks or more gestation
                         For babies of 38 or more weeks of gestation, the GDG agreed through an informal consensus
                         process that a reasonable threshold for initiation of phototherapy  was  350 micromol/litre  in
                         infants aged 96 hours or more. The GDG believed that this was consistent with current views on
                         the low risk associated with moderate hyperbilirubinaemia in term babies. The GDG discussed
                         a recent publication that provided data on current practice regarding thresholds for therapy in a
                                                      1
                         large  number  of  units  in  the  UK.   That  publication  did  not  draw  conclusions  regarding  ‘best
                         practice’ but did inform the group about the range of policies being used. The GDG noted that
                         their chosen phototherapy threshold was closely comparable with the most commonly reported
                                                                                 1
                         threshold (340 micromol/litre) currently used by units in the UK.  It was also comparable with
                         the threshold proposed by the American Academy of Pediatrics. 123  There was evidence that the
                         publication  of  the  AAP  recommendation  in  1994  had  not  been  associated  with  a  significant
                         change in the reporting of kernicterus cases in the USA. 124
                         For the period from birth to 96 hours, again based on informal consensus, the GDG agreed on a
                         series of bilirubin levels with  6-hourly stepwise increases at which phototherapy  is
                         recommended until the 96-hour  threshold of  350 micromol/litre  is  reached. These
                         recommended levels are presented in table form (see the threshold table in Section 1.3).

                         Phototherapy thresholds for infants less than 38 weeks of gestation
                         With regard to preterm babies, one longstanding and common approach has been to determine
                         the threshold for phototherapy using the simple formula
                            bilirubin in micromol/litre = (gestational age × 10) − 100

                         This formula has  been proposed for use in paediatric textbooks for many years. Based on
                         informal consensus, the GDG agreed that this formula should be used for babies aged 72 hours
                         or older. The GDG noted that use of this simple formula produced a threshold for phototherapy
                         that was either within or close to the middle quartiles for thresholds reported to be in current
                         use by neonatal units in the UK. They were therefore comparable with ‘average practice’ and
                         would avoid some of the more extreme values being employed in some units. The widespread
                         use of this formula is not likely to change the number of  preterm babies treated with
                         phototherapy in most neonatal units.
                         For all babies aged less than 72 hours, based on informal consensus, the GDG agreed that the
                         threshold should be lower because of the evidence that shows that bilirubin levels are rising for
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                         the first few days of life.
                         It was agreed for babies less than 38 weeks of gestation the threshold for phototherapy was best
                         presented using a series of graphs (see treatment threshold graphs) of total bilirubin versus age in
                         hours, with a separate graph for each gestational age (from 23 weeks to 37 weeks of gestation).
                         The graphs were constructed using the formula for infants of 72 hours of age and older. The
                         threshold  levels  during  the  first  72 hours  were  determined  by  drawing  a  straight  line  from  a
                         level of 40 micromol/litre (the upper limit of normal for the umbilical cord blood bilirubin) at
                         birth to the formula-based  level at 72 hours.  The GDG were aware that  Excel spreadsheets
                         originally  devised  by  Dr  Giles  Kendall  and  Professor  T  J  Cole  at  University  College  London
                         could potentially be used  to display the threshold levels in graphic  form. The GDG are grateful
                         to them for their kind permission to adapt these spreadsheets.
                         Exchange transfusion thresholds for babies of 38 weeks or more gestation
                         Similar considerations were applied to the choice of levels for  exchange transfusion. The
                         process was one of informal consensus by the GDG.


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