Fiber-optic phototherapy delivered via a fiber-optic cable to a transparent flat device (mat) that can be placed directly in contact with the infant skin has been demonstrated to be effective for neonatal hyperbilirubinemia.¹ The fiber-optic Biliblanket device (Ohmeda Critical Care, Columbia, MD) was found to be more effective than the Wallaby phototherapy system (Fiberoptic Medical Products Inc, Allentown, PA).⁴ However, in our experience the efficacy of the standard-size mat for full-term infants is distinctly less than that of conventional phototherapy using our own setup⁵; this was attributed to the relatively small size of the mat, resulting in exposure of the skin being limited to a small area. A bigger mat or two standard mats would improve the performance of fiber-optic phototherapy; the present report compares these two forms of phototherapy against that of a standard fiber-optic mat and conventional phototherapy in terms of efficacy and practicality.

METHODS

The irradiance of the standard fiber-optic device (without the sheath and set at maximal power) measured at the center and the four corners averaged 19.01 µW/cm² per nanometer; that of the seven overhead lamps averaged 6.73 µW/cm² per nanometer; the irradiance of the larger fiber-optic mat was similar to that of the standard mat; because of its larger size, the light dose of the larger mat would be about 23% more than that of the standard fiber-optic mat. Because of the different spectra of the two types of light, the irradiance values of the Biliblanket were 867 µW/cm² in the 400- to 480-nm range, 437.0 µW/cm² in the 425- to 475-nm range, 342.0 µW/cm² in the 440- to 480-nm range, and 775.8 µW/cm² in the 440- to 500-nm range; the values of the seven overhead lamps were 403.2, 205, 106.6, and 201.6 µW/cm², respectively. In the double-fiber-optic setup the total irradiance would be twice that of the standard fiber-optic mat. The irradiance in the blue spectrum was relatively low, but that in green spectrum was substantial in fiber-optic phototherapy (hence the greater values in the spectrum involving the 500-nm band). The measurements were made using an International Light (Newburyport, MA) 400A radiometer/photometer. Fluid intake was increased during phototherapy to offset the increased fluid loss during exposure.

Capillary blood was sampled at start of exposure and every 12 hours thereafter to monitor the serum bilirubin response to exposure. The lights were switched off during sampling. The capillary samples were placed in labeled red drinking straws and kept in a light-proof box until the moment of determination under standard conditions using an American Optical bilirubinometer, which was calibrated regularly against known standards.

In infants with increasing bilirubin values exceeding the starting value on two consecutive determinations during exposure, direct-acting bilirubin was determined as previously described;⁶ when this was minimal (<10 µmol/L [0.6 mg/dL]), phototherapy was deemed to have failed, and the infant was transferred to high-intensity phototherapy as previously described.⁸ Direct-acting bilirubin was also estimated in random samples.

Phototherapy was terminated when bilirubin values had declined to less than 185 µmol/L (11 mg/dL) on two successive estimations, the minimal duration being 24 hours; the prolonged central conduction time was observed to improve with bilirubin decline during exposure, complete reversal occurring 24 hours after cessation of exposure.⁷ Bilirubin levels were then monitored daily to determine the rebound, for at least 2 days; if rebound bilirubin concentrations increased beyond those of the prephototherapy values, additional phototherapy was performed following the same guidelines.

The nursing personnel caring for the infants were interviewed regarding convenience, ease of use, infant care, and acceptability of the fiber-optic device compared with conventional phototherapy. The parents were also interviewed regarding their reaction to the new device. Informed consent from the parent(s) and approval for this study from the director of medical affairs of the National University Hospital were obtained.

The data were statistically evaluated using analysis of variance, Student's t test, and the ² test.

RESULTS

Table 1. Data of Infants Studied [View Table]

Table 2. Decline of Bilirubin Concentration and Type of Phototherapy [View Table]

The direct-acting bilirubin was minimal in all the samples tested; all the values obtained were less than 10 µmol/L.

The nurses caring for the full-term infants were unanimous in their approval of the fiber-optic mat, being more comfortable without the conventional overhead phototherapy frame; absence of glare was a positive factor, although this was thought to be a minor problem. Cleaning the soiled fiber-optic mats was the only disadvantage, but this was offset by little need to clean the cots, otherwise required during conventional phototherapy. The nurses thought that the major drawback was the long duration of exposure imposed by the mats. The infants were immediately comfortable with the mats, manifesting none of the initial restlessness observed with conventional phototherapy. All the parents were reassured with the infants swaddled and without eye pads. However, the double-fiber-optic arrangement was found to be clumsy and difficult to apply neatly; nursing the infants was also inconvenient, and the cleaning of two mats for each case was deemed excessive and tedious. Feeding during exposure was also not convenient with two fiber-optic mats attached. However, the infants were not adversely affected.

DISCUSSION

The best results were obtained by double-fiber-optic phototherapy and conventional phototherapy; because twice the surface area was exposed in this double arrangement, the light dose was significantly increased, being twice that of standard fiber-optic phototherapy. The same light dose can be achieved by increasing the irradiance twofold without increasing the surface area; the effect would be the same.¹² The rate of response, however, was less than twice that of the latter, which was not surprising, given the pattern of response of hyperbilirubinemia to increasing irradiance.⁸ This type of phototherapy was more difficult and inconvenient to administer; nursing such infants was also relatively difficult. Cleaning two mats for each infant was an added inconvenience. With conventional phototherapy, probably about one third of the total skin surface area was exposed (about 730 cm²) compared with much less surface area exposed to the fiber-optic mats (143 and 176 cm² for the standard and large mats, respectively); hence, with conventional phototherapy, the total light dose (area exposed × irradiance) would be much greater even though the irradiance per unit area would be less. Our conventional phototherapy setup¹³ seemed more effective than the commercial sets currently on the market, despite being set 35 cm above the infant. Conventional phototherapy might therefore be preferable to double-fiber-optic phototherapy, although lack of glare in the latter would be an advantage. The interruptions for feeds during conventional phototherapy did not interfere with its efficacy; this is not unexpected, because short interruptions after about 3 hours of phototherapy¹⁴ have no impact on efficacy. Should maximal efficacy be required, our own double-bank blue-light phototherapy¹³ used at an optimal dose^11,13 should provide maximal efficacy in full-term infants with severe or rapidly increasing jaundice,¹⁵ especially of a hemolytic nature.

This study demonstrated that fiber-optic phototherapy with the Ohmeda Biliblanket in full-term infants was adequate for routine use only with the double arrangement, sandwiching the infant in between two mats. This apparent inadequacy of the standard fiber-optic Biliblanket for full-term infants reinforces our earlier study,⁵ in which exposure was too long, and failures occurred too often. Increasing the light dose and improving the spectral emission of the lamp used will enhance efficacy. If spectral emission were not improved, an increase in the light dose of 100% would be needed for performance comparable to that of conventional phototherapy; this would require an increase of light intensity, blanket size, or both. When the spectral emission of the light can also be improved, the overall light dose need not be increased to this degree to ensure the same result; a single enlarged mat with a more appropriate light spectrum might thus be comparable to conventional phototherapy in efficacy. When such a situation can be realized, then fiber-optic phototherapy, with its advantages of convenience, ease of use, freedom from obstruction, and easy accessibility, might then be able to achieve its full potential and be the preferred choice for treating neonatal hyperbilirubinemia. Until then, the present Ohmeda Biliblanket should mainly be used for small preterm infants who generally would respond adequately to such treatment.⁵