Effective Phototherapy

L S Deshmukh

DM ( Neonatology )

deshmukhls@yahoo.com

Introduction

• Phototherapy - mainstay of treatment

unconj. Hyperbili.

• PT is effective in reducing excessive

unconj. Hyperbili.

• drastically curtailed the use of ET

• Phototherapy should be regarded as a

drug, with an appropriate dose and

duration

PT – Indication

• The initiation and duration of PT decided by

- total bilirubin values

- an infant’s postnatal age

- the potential risk for bilirubin neurotoxicity

PT – Indication ( ≥35 wk )

2004 AAP guideline

J Clin Neonatol. 2013

PT - Indication(≤ 35 wk )

The Mechanism Of Phototherapy

Advances in Neonatal Care • Vol. 11, No. 5S, 2011

Efficacy of PT Devices

Depends on -

• Spectral qualities of the light source used (wavelength range and peak)

• Intensity of the light (irradiance)

• Body surface area exposed by the irradiated field or “footprint.”

• Distance between the light and the infant’s skin

Advances in Neonatal Care • Vol. 11, No. 5S, 2011

Optimal Administration of PT –

Practical Considerations

• Light source (wavelength) (nm)

• Light irradiance (W·cm2·nm1)

• Body surface area (cm2)

• Continuity of therapy

• Efficacy of intervention

• Duration of therapy

Optimal Administration of PT

Light source (wavelength) (nm)

Practice Considerations - Light source (nm)

• Recommendation - Wavelength spectrum in

460- 490-nm blue-green light region

• Imp. - Know the spectral output of the light

source

Pediatrics 2011;128;e1046

Light source /Wavelength

• visible white light spectrum - 350 to 800 nm

• Bilirubin absorbs visible light most strongly

in the blue region of the spectrum (~460 nm)

• the most effective light in vivo is probably

in the blue-to-green region (460–490 nm).

Light source /Wavelength

Commercial Light Sources

• Fluorescent

- cool white daylight

- blue [B]

- special blue [BB]

- Turquoise and green

• narrow-band special blue bulbs

- TL52/20W [Phillips] or

- F20T12/BB [GE]

- More effective

Light source /Wavelength

• Special blue (BB) fluorescent lights

- not be confused with white lights painted

blue or covered with blue plastic sheaths

• Unless specified otherwise, plastic covers

or optical filters need to be used to remove

potentially harmful UV light.

Light source /Wavelength

• commercial compact fluorescent-tube

light (CFL) sources

• LEDs of narrow spectral bandwidth

- used as over- and under-the-body

devices.

• Fiberoptic - pads, blankets

• Halogen - spotlights

Light source /Wavelength

• High intensity gallium nitride LEDs with

emission within the 460- to 490-nm regions

are as effective as CFL / Conventional

- lower heat output,

- low infrared emission, and

- no ultraviolet emission

- a longer lifetime (20 000 hours)Adv Biomed Res. 2012; 1: 51.

Optimal Administration of PTLight Irradiance

Light Irradiance (intensity )

• Light intensity or energy output is defined by irradiance

• number of photons (spectral energy) that are delivered per unit area (cm2) of exposed skin

• The dose of phototherapy - measure of the irradiance delivered for a specific duration and

adjusted to the exposed body surface area (µW·cm2·nm)

Light Irradiance

• Recommendation : Use optimal irradiance

• The recommended minimal irradiance levels

are 8– 12 µW⁄cm2 ⁄nm

• for intensive PT ≥30 W·cm2·nm within the

460- to 490-nm waveband

• Imp: Ensure uniformity over the light footprint

area

Pediatrics 2011;128;e1046

Light Irradiance

• Devices that emit lower irradiance may be supplemented with auxiliary devices

• bringing the light source close to the infant increases irradiance

- Caution : not be done with halogen lights

The ideal distance and orientation of the light source should be maintained according to the manufacturer’s recommendations

• The irradiance of all lamps decreases with use

Optimal Administration of PT

Body surface area (cm2)

Practice Considerations –

Body surface area (cm2)

• Recommendation : Expose maximal skin area

• Imp : Reduce blocking of light

Pediatrics 2011;128;e1046

Body Surface Area

• Complete (100%) exposure of the total body

surface to light is impractical and limited by use

of eye masks and diapers

• Circumferential illumination achieves exposure of

approximately 80% of the total body surface.

• In clinical practice, exposure is usually planar

(ventral or dorsal)

• Approximately 35% of the total body surface is

exposed with either method

Body Surface Area

• Changing the infant’s posture every 2 to 3 hrs

-maximizes the area exposed to light

• Exposed body surface area treated rather than

the number of devices (double, triple, etc)

used clinically more important

• Physical obstruction of light by equipment

decreases the exposed skin surface area

Pediatrics 2011;128;e1046

Body Surface Area

• Combining several devices, will increase the

surface area exposed.

- placing a light source beneath the infant

• reflecting material around the incubator or

radiant warmer bed useful

Pediatrics 2011;128;e1046

Imp Factors in the Efficacy of PT

N Engl J Med 2008;358:920-8.

Optimal Administration of PT

Continuity of therapy

Practice Considerations

• Continuity of therapy as far as possible

• Recommendation : Briefly interrupt for

feeding, parental bonding, nursing care

• Imp : After confirmation of adequate

bilirubin concentration decrease

Pediatrics 2011;128;e1046

Optimal Administration of PT

Efficacy of intervention

Practice Considerations

• Efficacy of intervention

• Recommendation : Periodically measure

rate of response in bilirubin load reduction

• Imp : to look at , Degree of total serum

bilirubin concentration decrease

Pediatrics 2011;128;e1046

Efficacy of intervention

- Rate of Response

• The clinical response depends on

the rates of bilirubin production

enterohepatic circulation

bilirubin elimination

the degree of tissue bilirubin deposition

the rates of the photochemical reactions of

bilirubin.

Efficacy of intervention

- Rate of Response

• The clinical impact of phototherapy should

be evident within 4 to 6 hours

• Decrease of more than 2 mg/dL in serum

bilirubin concentration.

• Periodicity of serial measurements is based

on clinical judgment.

Optimal Administration of PT

• Practice Considerations - Duration of therapy

• Recommendation : Discontinue at desired

bilirubin threshold, be aware of possible

rebound increase

• Imp : Serial bilirubin measurements based on

rate of decrease

Pediatrics 2011;128;e1046

Failure of PT

• an inability to observe a decline in bilirubin of

1-2 mg/dL after 4-6 hours and/or

• to keep the bilirubin below the BET level.

• ? Consider intensive PT

• No Role of prophylactic PT in preterm babies

NNFguidelines2010

Stopping Phototherapy

• serum bilirubin level has fallen below 2mgs/dL

lower than threshold

• Check for rebound

Consider if prematurity, direct Coombs test

positivity, and those treated < 72 hours.

Not indicated if, non-hemolytic etiology and an

early follow up after discharge

NNFguidelines2010

Phototherapy Infants ≤ 35 weeks GA

• Generally used in a prophylactic mode

• goal - to prevent further elevation TSB

• at least in infants with BW<750 g, initiate

phototherapy at lower irradiance levels

• increase irradiance levels, or increase the

surface area of the infant exposed to PT,

if the TSB continues to rise

MJ Maisels et al , 2012

Measuring Light Irradiance

• Visual estimations of brightness & use

of ordinary photometric/colorimetric

light meters are inappropriate

• measured with a radiometer (W·cm2)

or spectroradiometer (W·cm2·nm1)

over a given wavelength band.

Measuring Light Irradiance

• Irradiance should be measured at several

sites on the infant’s body surface

• different radiometers may show different

values for the same light source

• Use manufacturer recommended

Measuring Light Irradiance

• For improving the application of effective phototherapy, need to develop an affordable, user-friendly, handheld, universal irradiance meter which accurately measures irradiance delivered by all types of phototherapy light sources.

Vreman HJ, Indian Pediatr, 2010

Safety And Protective Measures

• Four decades of neonatal phototherapy use

- no serious adverse clinical effects

• Ensure adequate hydration, nutrition, and

temperature control.

• Devices - Must meet electrical and fire hazard

safety standards (IEC )

Safety And Protective Measures

• Eye patches - Purulent eye discharge and

conjunctivitis in term infants with prolonged

use

• Use of diapers: Diapers may be used for

hygiene but are not essential.

• PT Contraindication

- infants with congenital porphyria or those

treated with photosensitizing drugs.

PT- Sunlight

• Sunlight will lower the serum bilirubin level,

the practical difficulties involved in safely

exposing a naked newborn to the sun either

inside or outside (and avoiding sunburn)

preclude the use of sunlight as a reliable

therapeutic tool.

Transcutaneous Bilirubinometry (TcB)

Pathak U et al, IJP, 2013

Key Messages 1

• Use special blue tubes or LED light source with output in blue-green spectrum

• If special blue fluorescent tubes are used, bring tubes as close to infant as possible to increase irradiance

• For intensive PT, expose maximum surface area of infant to PT.

• Place lights above and fiber-optic pad or special blue fluorescent tubes* below the infant.

Key Messages 2

• Intensive PT requires >30 μW/cm2 per nm.

• For maximum exposure, line sides of bassinet, warmer bed, or incubator with aluminum foil.

• Use intensive PT for higher TSB levels.

• Periodically measure rate of response

• Monitor Irradiance