Dear Editor

Walker et al.[1] have highlighted the diversity in practice in the management of sick neonates with established meconium aspiration syndrome (MAS) and refractory pulmonary hypertension. We report our experience with five infants, among 1419 neonatal admissions, who required transfer for ECMO support between 1998-2002.

Table 1 gives the summary of the cases. Infant 2 developed progressive respiratory distress at 18 hours of age and died after 4 days on ECMO. Infant 3 with congenital diaphragmatic hernia (CDH) had a mean pH of 7.24 (range 7.13-7.3) prior to transfer and showed a poor response to Tolazoline and Magnesium sulphate therapy. He received Inhaled Nitric Oxide (iNO) following transfer and was on ECMO support for 4 days prior to surgery. Infant 5 developed progressive respiratory distress with the clinical and radiological evidence of severe Surfactant Deficiency Lung Disease (SDLD). Progressive hypoxaemia and metabolic acidosis were unresponsive to alkali therapy and administration of iNO (portable iNO) brought some improvement. All infants received surfactant and required inotrope support before and during transport. All infants had normal core temperature and blood pressure at transfer. Oxygenation Index >40 is considered a clear evidence of inadequate oxygenation.[2] In our infants (OI >40) transfer for ECMO was considered when hypoxaemia showed poor response to conventional ventilation. Most district general hospitals have no access to iNO or HFOV. Faced with a sick infant with persistent hypoxaemia , there are limited options for further treatment. We would like to support the recommendation that in these infants ECMO should be considered early and would like to add that adequate attention should be given to inotrope support, acid base balance and maintenance of normothermia prior to the arrival of transport team.

Table 1 Summary of events prior to E.C.M.O transfer and immediate outcome

Characteristics
	Infant 1	Infant 2	Infant 3	Infant 4	Infant 5
Diagnosis	MAS	GBS infection	CDH	MAS	PPHN
Sex	Male	Male	Female	Male	Male
Birth Weight (g)	3720	3540	4100	2950	3100
Mode of Delivery	N	N	LSCS	LSCS	LSCS
Age at intubation (h)	1	20	Birth	2	25
Oxygenation Index (OI)	43	40.6	44.9	40.8	54.1
pH	7.33	7.43	7.22	7.39	7.27
PCO2	5.34	3.1	4.87	4.33	5.4
Age at transfer (h)	7	36	9	12	39
Duration of ECMO (d)	3	4	5	3	4
Outcome	Survived	Died	Survived	Survived	Survived

Footnote
MAS- Meconium Aspiration Syndrome
GBS- Group B Streptococcus
CDH- Congenital Diaphragmatic Hernia
PPHN- Persistent Pulmonary Hypertension of Newborn
LSCS- Lower Segment Caesarean Section

References

(1) Walker GM, Coutts JAP, Skeoch C, Davis CF. Paediatricians’ perception of the use of extracorporeal membrane oxygenation to treat meconium aspiration syndrome. Arch Dis Child Fetal Neonatal Ed 2003;88:F70-F71

(2) Field D. Management of persistent pulmonary hypertension of the newborn. Current Paediatrics (Mini-symposium: Neonatology) 1997;7:73-77.

Dear Editor

We would like to thank Dr Nicholl for his comments on the use of surfactant in MAS. We endorse the view that use of surfactant has some benefit in the management of infants with respiratory failure secondary to MAS. However, meconium is a very potent inactivator of surfactant and some of the benefit may be related to the lavage effect of the technique. The purpose of our study was not to investigate all possible therapies. The impetus to carry out the questionnaire study was twofold; to identify the prevalence of what we considered to be “harmful treatments”, in particular intravenous vasodilators and hyperventilation to alkalosis, and to determine the current referral practices of consultant paediatricians. We would again stress the need for early contact with an ECMO centre in infants with MAS who are failing conventional management regardless of therapies used. We feel that surfactant can be used in these infants but not if this will delay the transfer of a child to an ECMO unit. Compared to conventional management, ECMO has been shown to be beneficial in both the short-term survival and in the long term neurodevelopmental and respiratory outcome of these children. Therefore, avoidance of ECMO may not be a good outcome measure in studies.

Dear Editor

I was surprised that surfactant was not mentioned in this article (or was not asked about in the questionnaire?). There is good evidence that in babies with respiratory failure due to MAS, surfactant may prevent the need for ECMO. I attach our critically appraised topic ("CaT") on this for the readers of Archives:

Surfactant replacement therapy for meconium aspiration syndrome (MAS) reduced the need for ECMO.
Appraisers: Consultant(s) Nicholl: Specialist Registrar(s): Marx Senior House Officer(s): Amarasinghe, Swanepoel, Gillham
Date: 8.10.98

The pt was: a full term infant, ventilated for MAS

Clinical bottom lines:
1. Surfact replacement therapy in term infants with moderately severe MAS (OI=20) resulted in an 83% relative risk reduction in the need for ECMO.

2. The number of babies needed to treat (NNT) to prevent one case proceeding to ECMO was 4-5 patients.

The evidence:
1. RCT (n=40) of term MAS . with OI around 20 at entry (age 6 hrs). Received Survanta, 150mg/kg, 6hrly for 3 doses or air placebo.

2. Multicentre (n=44) RCT of term infants (n=328) with resp. failure . Stratified by diagnosis (MAS, sepsis and PPHN) and disease severity (OI <_23 _23-30="_23-30">30).Randomised (up to 5 days) to receive 4 doses of Survanta, 100mg/kg, 6 hrly, or air placebo before ECMO treatment and after, if ECMO was required.

Findlay: 

Event	CER	EER	RRR	ARR	NNT
Need for ECMO (%)	30	5	83	25	4

Lotze:

	CER	EER	RRR	ARR	NNT
Need for ECMO if:
All in study (%)	40	29	28	11	9
OI <_23 _="_" b="b">	33	12	64	21	4.8
OI 23-30 (%)	41.3	34.2	17	7.1	14
OI> 30 (%)	53.6	48.5	10	5.1	20
MAS (%)	52	37	29	15	6
Sepsis (%)	27	16	41	11	9
PPHN (%)	32.3	30	7	2.3	43

Comment:
Different surfactant doses used. Method of randomisation not clearly stated in first paper. Apparent benefits also in terms of air leaks, duration of ventilation and oxygen days and admission in Findlay paper supports the idea that earlier treatment of MAS with surfactant has better outcomes.

References
Findlay RD, Taeusch HW, Walther FJ. Surfactant replacement therapy for meconium aspiration syndrome. Pediatrics 1996;97Jan.

Lotze et al.Multicentre study of surfactant (beractant) use in the treatment of term infants with severe respiratory failure. J of Pediatrics 1998; Jan.