PEDIATRICS Vol. 107 No. 3 March 2001, pp. 610-611

Phototherapy and Mesenteric Blood FlowToo Much, Not Enough, or the Wrong Kind?

`Give me a light that I may thread safely into the unknown.'

M. L. Haskins in `God Knows'

To the Editor.

In a recent publication in Pediatrics, Pezzati et al¹ describe the effects of phototherapy on mesenteric blood flow in premature infants. Their findings suggest that although standard phototherapy blunts the normal postprandial increase in mesenteric blood flow, fiber-optic phototherapy does not affect this normal response. Based on this finding, they conclude that fiberoptic phototherapy (FO-PT) is preferable to conventional phototherapy in premature infants. Although their finding is of significant interest and certainly worthy of additional study, their recommendation seems premature for several reasons.

First, although I don't mean to quarrel with the notion that an intervention that preserves normal physiology may be preferable to one that alters physiological responses, the authors have not shown that the blunted postprandial response shown in the infants under normal phototherapy lights has caused any clinical distress to these infants. Second, in their discussion the authors have cited literature to show that insensible water loss and thus water and electrolyte balance is significantly affected by conventional phototherapy.^2,3 However, they have omitted newer data which showed that in a temperature- and humidity-controlled environment, phototherapy neither influenced insensible water loss, nor respiratory water loss or oxygen consumption.^4,5

Third, the average duration of phototherapy was 80 hours in Pezzati et al's study.¹ We are not told what the phototherapy limits are in their nursery, but it seems that either their intervention limits must be low, or the efficiency of the phototherapy they supply must be mediocre. Pezzati et al performed their measurements of mesenteric blood flow at the end of this long treatment period. It is necessary to ask whether the effects they find are attributable to a flawed phototherapy regime, or to extraordinarily long treatment periods, or whether these findings would also be relevant to infants in other neonatal intensive care units (NICUs). In our NICU the average duration of phototherapy per treated patient with a birth weight (BW) between 1500 and 2500 g is ~20 hours, and in our well-baby nursery the average duration for term/near-term infants is ~17 hours.

As mentioned by Pezzati et al,¹ studies comparing conventional with FO-PT have yielded conflicting results. The obvious drawback of the fiberoptic devices is the limited skin area that actually receives therapy. The head is the most jaundiced part of the body but is excluded from irradiation by the fiberoptic devices. A conventional phototherapy unit that does not outperform fiberoptic devices is, therefore, in all likelihood flawed and needs to be checked and perhaps altered. The pros and cons of various approaches to phototherapy were recently eloquently discussed by Maisels.⁶

Thus, the findings by Pezzati et al¹ are important and interesting, but the choice of the most suitable approach to phototherapy in any given circumstance entails a careful weighting of the needs of that particular infant. Although mesenteric blood flow may well be one of the factors that need to be considered, given the present state of our knowledge it may not yet merit the preeminence suggested by Pezzati et al.¹

Thor W. R. Hansen
National Hospital
University of Oslo
Oslo, Norway

REFERENCES

1. Pezzati M, Biagiotti R, Vangi V, Lombardi E, Wiechmann L, Rubaltelli FF Changes in mesenteric blood flow response to feeding: conventional versus fiberoptic phototherapy. Pediatrics. 2000; 105:350-353 [Abstract/Free Full Text]
2. Oh W, Karecki H Phototherapy and insensible water loss in the newborn infant. Am J Dis Child. 1972; 124:230-232 [Abstract/Free Full Text]
3. Oh W, Williams PR, Yao AC, Lind J. The effect of phototherapy on insensible water loss and peripheral blood flow. Birth defects: Original article series. 1976;12:114-120
4. Kjartanson S, Hammarlund K, Sedin G Insensible water loss from the skin during phototherapy in term and preterm infants. Acta Paediatr. 1992; 81:764-768 [Medline]
5. Kjartanson S, Hammarlund K, Riesenfeld T, Sedin G Respiratory water loss and oxygen consumption in newborn infants during phototherapy. Acta Paediatr. 1992; 81:766-773
6. Maisels MJ Why use homeopathic doses of light? Pediatrics. 1996; 98:283-287 [Abstract/Free Full Text]

In Reply.

Dr Hansen asserts that our findings are important and interesting but that our recommendation seems premature for several reasons.

In our study we found that conventional phototherapy (CPT) compared with fiberoptic phototherapy (FO-PT) determined greater intestinal disturbances (increased passage of loose watery stools and abdominal distension) without statistically significant differences. The blunted postprandial response found in the infants under CPT may in part account for the phototherapy-related intestinal disturbances.¹ Furthermore, we showed that CPT compared with FO-PT induced a significant increase in skin temperature. Actually, the studies of Kjastanson et al^2,3 showed that CPT neither influenced insensible water loss nor respiratory water loss or oxygen consumption, but in their works all infants were studied "naked in an incubator with an ambient relative humidity of 50% and with a controlled environment with respect to temperature and air velocity." We omitted this data because in our trial a large number of infants were studied in beds (FO-PT allows for this kind of practice, and it undoubtedly makes the care, especially of the preterm infants, more comfortable).

In our research, phototherapy was initiated and stopped according to the guidelines by Maisels.⁴ The average duration of phototherapy of 80 hours is indeed rather long, but it is not much more than the duration of 44.1 hours described by Yao et al.¹ This value is related to a group of full-term infants with a mean BW of 3340 g, while we studied only preterm newborns (the mean BW was 2101 g; range: 1260-2750) who usually need a longer treatment time.

One of the major concerns in the use of FO-PT is the small size of the luminous pad available at present that limits the skin area receiving therapy. This problem is less important for preterm infants; better phototherapy efficiency has in fact been found in low birth weight infants (completely covered by the FO pad) as noted by Tan.⁵

We agree with Dr Hansen when he says that "the choice of the most suitable approach to phototherapy in any given circumstance entails a careful weighting of the needs of that particular infant." We think that a preterm infant can be considered a "particular infant." Thus, because of FO-PT's efficiency in the preterm newborn, it is possible to wrap the infant, thus enhancing the infant's postural and autonomic stability; it is not necessary to cover the infant's eyes because FO-PT does not induce an increase in skin temperature. Finally, because FO-PT preserves normal gastrointestinal physiology, we still consider FO-PT to be preferable to CPT for the therapy of hyperbilirubinemia in preterm newborns.

Marco Pezzati
Department of Pediatrics, Division of Neonatology
University of Firenze School of Medicine
Viale Morgagni 85-50134 Firenze, Italy

REFERENCES

1. Yao AC, Martinussen M, Johansen OG, Brubakk AM Phototherapy-associated changes in mesenteric blood flow response to feeding in term neonates. J Pediatr. 1994; 124:309-312 [Medline]
2. Kjartanson S, Hammarlund K, Sedin G Insensible water loss from the skin during phototherapy in term and preterm infants. Acta Paediatr. 1992; 81:766-773
3. Kjartanson S, Hammarlund K, Riesenfeld T, Sedin G Respiratory water loss and oxygen consumption in newborn infants during phototherapy. Acta Paediatr. 1992; 81:766-773
4. Maisels MJ. Jaundice. In: Avery GB, Fletcher MA, MacDonald MG, eds. Neonatology. Pathophysiology and Management of the Newborn. Philadelphia, PA: Lippincott; 1994:630-725
5. Tan KL Comparison of the efficacy of fibreoptic and conventional phototherapy for neonatal hyperbilirubinemia. J Pediatr. 1994; 125:607-612 [CrossRef][Medline]