Journal of Pediatric Ophthalmology and Strabismus

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Letters to the Editors 

Frequent ROP Associated With Hypoxic Protocol

Lucas Pratt; Robert W. Arnold, MD; Jacob Jack, MD

Abstract

To the Editors:

Chow et al.1 suggested a protective effect on retinopathy of prematurity (ROP) by careful control of neonatal oxygen saturation similar to in utero conditions. Others have not been able to achieve the same success.2 At approximately the same time, modifications in the definition of threshold ROP were published.3 The Alaska neonatal intensive care unit (NICU) has a high proportion of high-risk race (Alaska native and Asian) infants.4 We wondered if our initial implementation of a reduced oxygen saturation policy would lead to reduced rates of new threshold ROP.

Abstract

To the Editors:

Chow et al.1 suggested a protective effect on retinopathy of prematurity (ROP) by careful control of neonatal oxygen saturation similar to in utero conditions. Others have not been able to achieve the same success.2 At approximately the same time, modifications in the definition of threshold ROP were published.3 The Alaska neonatal intensive care unit (NICU) has a high proportion of high-risk race (Alaska native and Asian) infants.4 We wondered if our initial implementation of a reduced oxygen saturation policy would lead to reduced rates of new threshold ROP.

Drs. Arnold and Jacob are board members of Glacier Medical Software, which develops ROP monitoring software.

To the Editors:

Chow et al.1 suggested a protective effect on retinopathy of prematurity (ROP) by careful control of neonatal oxygen saturation similar to in utero conditions. Others have not been able to achieve the same success.2 At approximately the same time, modifications in the definition of threshold ROP were published.3 The Alaska neonatal intensive care unit (NICU) has a high proportion of high-risk race (Alaska native and Asian) infants.4 We wondered if our initial implementation of a reduced oxygen saturation policy would lead to reduced rates of new threshold ROP.

With Institutional Review Board approval from Providence Hospital, we have retrospectively monitored outcomes of ROP in Alaska since September 1989. In October 2004, we implemented two important changes: reduced goal oxygen saturations from very low birth weight infants and a transition from the 1989 ICROP definition of threshold ROP to recent ROP threshold guidelines—specifically stage 2, zone 2 with plus disease and advanced posterior ROP.3

The reduced oxygen levels were monitored transcutaneously with the goal of 88% to 92% with the Masimo monitor system (Masimo Corporation, Irvine, CA). NICU staff were given an inservice presentation on the use of Masimo oxygen saturation monitoring and urged to keep their patients within goal range. The staffing level for these infants was 1 to 3 infants per nurse with one neonatal respiratory therapist per 8 to 15 patients. We monitored patients’ gender, birthweight, gestational age, maternal-stated race, and the most severe level of ROP reached.

The cumulative trend of infants reaching threshold ROP versus date is shown in the figure. The interval between threshold treatments was less for the 35 patients who received less oxygen (27 ± 8 days; standard error of the mean) versus the 107 patients before oxygen reductions (52 ± 5 days; analysis of variance, F = 6.6, P = .01). Since we began reduced oxygen saturation, 5 infants have been referred for ROP worse than stage 3; before reduced oxygen saturation, only 10 patients progressed to ROP worse than stage 3.

Cumulative Trend of Alaska Neonates Reaching Threshold Retinopathy of Prematurity (ROP). In October 2004, Two Changes Were Implemented: Very Low Birth Weight Infants Had Goal Oxygen Saturation Monitored Transcutaneously by the Masimo System (Masimo Corporation, Irvine, CA) Between 88% and 92%, and the Definition of ROP Threshold Was Liberalized to Include Stage 2, Zone 2 with plus Disease and Advanced Posterior ROP.

Figure. Cumulative Trend of Alaska Neonates Reaching Threshold Retinopathy of Prematurity (ROP). In October 2004, Two Changes Were Implemented: Very Low Birth Weight Infants Had Goal Oxygen Saturation Monitored Transcutaneously by the Masimo System (Masimo Corporation, Irvine, CA) Between 88% and 92%, and the Definition of ROP Threshold Was Liberalized to Include Stage 2, Zone 2 with plus Disease and Advanced Posterior ROP.

Simple adoption of reduced oxygen saturation goals combined with new ROP threshold guidelines did not result in a reduced frequency of threshold ROP in the level 3 NICU in one high-risk state. Strict adherence and close staff monitoring may be required to achieve reductions in ROP severity. We urge careful evaluation of staff adherence and oxygen saturation goals. We hope that protocols and staff education, and feedback oximeter–ventilator mixer technology, will allow better adherence with guideline ranges and that we can reduce the prevalence of threshold ROP.5

Lucas Pratt1
Robert W. Arnold, MD1
Jack Jacob, MD2
Ophthalmic Associates1
and
Alaska Neonatology Associates2
Anchorage, Alaska

References

  1. Chow LC, Wright KW, Sola A. Can changes in clinical practice decrease the incidence of severe retinopathy in very low birth weight infants?Pediatrics. 2003;111:339–345. doi:10.1542/peds.111.2.339 [CrossRef]
  2. Wallace DK, Veness-Meehan KA, Miller WC. Incidence of severe retinopathy of prematurity before and after a modest reduction in target oxygen saturation levels. J AAPOS. 2007;11:170–174. doi:10.1016/j.jaapos.2006.08.012 [CrossRef]
  3. Early Treatment for Retinopathy of Prematurity Cooperative Group. Revised indications for the treatment of retinopathy of prematurity: results of the Early Treatment for Retinopathy of Prematurity Randomized Trial. Arch Ophthalmol. 2003;121:1684–1694.
  4. Lang D, Blackledge J, Arnold R. Is Pacific race a retinopathy of prematurity risk factor?Arch Pediatr Adolesc Med. 2005;159:771–773. doi:10.1001/archpedi.159.8.771 [CrossRef]
  5. Nghiem TH, Hagadorn JI, Terrin N, Syke S, MacKinnon B, Cole CH. Nurse opinions and pulse oximeter saturation target limits for preterm infants. Pediatrics. 2008;121:e1039–e1046. doi:10.1542/peds.2007-2257 [CrossRef]
Authors

Drs. Arnold and Jacob are board members of Glacier Medical Software, which develops ROP monitoring software.

10.3928/01913913-20090706-17

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