Introduction

There is no consensus concerning perinatal treatment of patients with congenital diaphragmatic hernia (CDH). Increasingly, CDH is diagnosed prenatally [1], and most authors advocate a planned delivery close to term at a tertiary centre [2]. However, centres vary in several important aspects of perinatal management [1, 3, 4].

During the last decade several new supportive CDH-treatment modalities have been introduced. The effects of these modalities has been sparsely documented [5]. The UK ECMO trial showed no significant survival benefit of ECMO in CDH patients [6, 7]. The advantage of ECMO in severe respiratory failure in newborn infants is less clear for CDH patients than for babies without CDH [8]. Randomised controlled trials (RCT) addressing the effect of nitric oxide (NO) in CDH patients reported no significant advantage of NO treatment [9, 10]. Two RCTs comparing early and delayed surgery failed to show any significant difference in survival between the two groups [11, 12], a finding that is in accordance with a recent systematic review [13]. Comparative studies have given important clues regarding ventilator settings; and gentle ventilation with permissive hypercapnea has been found to result in improved survival [1, 4, 14, 15]. A large study by the CDH Study Group revealed no consistency among centres in treatment strategies [16].

The lack of consensus on how to treat CDH patients prompted us to survey current practice in Scandinavia.

Material and methods

Thirteen paediatric surgical centres in the four Scandinavian countries were identified: two in Denmark, four in Finland, three in Norway, and four in Sweden. The population served by these centres is about 22 million, with approximately 280,000 births per year.

We conducted a cross-sectional survey with the centre as the unit of investigation. In order to increase the participation rate and according to the study protocol, the results of the participating centres are reported anonymously. One self-explanatory questionnaire in English was mailed to the head of each centre in October 1999. All centres participated, and all questionnaires were completed by March 2000. Twelve questionnaires were completed by paediatric surgeons and one by a paediatrician. The questionnaire included 28 items covering aspects of perinatal treatment following prenatal diagnosis, intensive care strategies, operative procedures, and long-term follow-up routines (Table 1). Centres that reported treating more than five CDH patients a year were defined as “high-volume centres”.

Table 1 Outline of the questionnaire used to survey current CDH management
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In a previous study, we retrospectively collected clinical data on 195 CDH patients (1995–1998) from 12 of the 13 centres participating in the present study [17]. Thus, available survival data predate the present questionnaire data. Survival to discharge is reported herein. In the present study, institutions treating more than five CDH patients a year were compared with those treating five or fewer. Risk stratification into three groups was performed as previously described by the CDH Study Group [18]. Statistical analyses were performed using SPSS version 11.0 (SPSS, Chicago, USA).

Results

The median estimated number of CDH patients was four per year (range 1–10) at each centre (Fig. 1). Three centres reported that they treat more than five CDH patients a year (“high-volume centres”).

Fig.
figure 1

 1 Estimated annual number of CDH patients per centre in Scandinavia. Note: In accordance with study protocol, the identities of the participating centres are anonymous

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Following prenatal diagnosis, a scheduled delivery close to term at a paediatric surgical centre was routine at all centres. Five centres planned delivery during week 38, three centres during week 39, and five centres during week 40. Six centres administered maternal steroids prenatally. Following prenatal diagnosis, eight centres (including two high-volume centres) preferred to deliver the baby vaginally, four preferred elective Cesarean section (including one high-volume centre), and one centre had no preference.

Prophylactic intubation of patients with CDH was favoured at four centres, whereas nine centres did not intubate until respiratory failure occurred. Eleven of 13 centres (including all three high-volume centres) preferred gentle ventilation with permissive hypercapnea. One centre applied a hyperventilation strategy, and one centre aimed at normal blood gases. Only five of 13 centres answered the question concerning positive end-expiratory pressure (PEEP). The median maximal PEEP in these centres was 4 cm H2O (range 1–5 cm H2O). Four centres responded to the question regarding peak inspiratory pressure (PIP). The median of the maximal PIP in these centres was 25 cm H2O (range 20–30 cm H2O).

Supportive treatment with surfactant, nitric oxide (NO), and high-frequency oscillation ventilation (HFOV) was commonly used (Table 2). Nine centres sometimes used ECMO. Five centres had ECMO facilities, and four centres had to transfer the ECMO candidate either by conventional transport or by using mobile ECMO if ECMO treatment was considered necessary [19]. In seven of nine centres HFOV was always tried before ECMO was started. The two remaining centres responded that HFOV frequently was tried before ECMO was started.

Table 2 Frequency of use of intensive care modalities in the management of CDH at 13 Scandinavian centres ( NO nitric oxide, HFOV high-frequency oscillation ventilation, ECMO extracorporeal membrane oxygenation)
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Delayed surgery, defined as that taking place after 24 h of age, was preferred at 12 centres and at two of three high-volume centres. A clinically stable patient was the most important criterion (12/13) for determining time of operation. Seven centres required that preoperative echo-Doppler demonstrated no signs of pulmonary hypertension. All centres performed repair by laparotomy. Nonabsorbable sutures were used at eight of 13 centres. Large defects were most commonly closed by a Gore-Tex patch (10/13). Routine appendectomy and Ladd’s procedure for malrotation were only performed at one and two centres, respectively.

Routine long-term follow-up at the perinatal centre was uncommon, occurring in only three centres.

The overall survival rate (1995–1998) was 65% in 168 neonates with early symptoms (≤24 h) and 100% in 27 children with late symptoms [17]. The survival rate (neonates with early symptoms) in high-volume centres was 72.4% (55/76), compared with 58.7% (54/92) in non-high-volume centres (chi square =3.41, p =0.065). The data needed to calculate risk stratification groups were available for 152/168 neonates with early symptoms. Survival by hospital volume for those with predicted low, moderate, and high mortality risk is presented in Table 3.

Table 3 Survival to dischargea in CDH neonates with early symptoms (≤24 h) by hospital volume and stratified for risk
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Discussion

The present study demonstrates that perinatal management of CDH patients differs widely across Scandinavia. The lack of harmonisation of CDH treatment in Scandinavia may be a consequence of lack of firm evidence about many aspects of perinatal CDH treatment. This is in accordance with the fact that most surgical procedures are not based on evidence from RCTs [20, 21].

The present study was not designed to compare outcome as a consequence of the reported management strategies. For this purpose, additional data are needed, and we intend to conduct such a study.

In accordance with the literature, all Scandinavian centres preferred that delivery after prenatal diagnosis take place close to term at a paediatric surgical centre [2, 22]. Eight of 13 centres preferred vaginal delivery, which is consistent with the fact that no study has demonstrated any benefit of routine Cesarean delivery of prenatally-diagnosed CDH patients [17, 23].

About half of the centres administered maternal steroids prenatally. None of these centres participated in any ongoing steroid trial. The relatively widespread use of prenatal maternal steroids following a prenatal diagnosis of CDH may be due to encouraging results in animal models [24], but the effect of prenatal maternal steroid treatment has only been reported in case series [25, 26].

The majority of centres (11/13) applied a gentle ventilation strategy with permissive hypercapnea. This strategy is highly beneficial according to large series, using historical comparisons, showing reduced frequency of barotrauma and superior survival after its implementation [1, 4, 15, 27].

The Scandinavian centres comparatively often used surfactant, NO, and HFOV, with infrequent use of ECMO. An intensive care strategy with infrequent use of ECMO has been shown to result in up to 80% survival [28]. Trials on NO treatment have shown no benefit in CDH patients as opposed to other causes of respiratory failure in neonates [9, 29]. No trials have been published evaluating the use of HFOV in CDH patients. Future trials are needed to evaluate the effectiveness of surfactant, NO, and HFOV in the management of CDH patients [5].

The UK ECMO trial did not show a significantly increased survival in CDH patients treated with ECMO compared with those treated without ECMO. However, only 35 CDH patients were included in that study [6]. Improved survival rates with ECMO have been reported in clinical series with historical controls [30, 31]. Moreover, a systematic review based on observational studies showed reduced preoperative mortality in the ECMO centres [32]. Stratified analysis of the CDH Registry data showed increased survival in the ECMO group among the most severely affected CDH patients [33]. Planned delivery of prenatally diagnosed CDH patients at an ECMO centre has been advocated [2]. We believe that the lack of firm evidence in favour of ECMO is the reason why this recommendation has not yet been implemented in all Scandinavian centres.

Most Scandinavian centres prefer delayed surgery, repair by laparotomy, and a low rate of appendectomy and malrotation procedures. This is in agreement with the data from the CDH Study Group [16].

The finding of varied clinical practice calls for prospective multicentre trials on management strategies. Treatment should be standardised in uncontroversial areas, and outcome data should be collected prospectively. Multicentre collaboration has been very helpful in some areas of paediatric surgical research [34], and a similar approach is encouraged for CDH research.

There is a reported long-term morbidity of up to 50% in CDH patients. Gastro-esophageal reflux, pulmonary problems, late bowel obstruction, nutritional problems, hearing problems, and skeletal malformations have been documented [5].Only three Scandinavian centres routinely arranged long-term follow-up of their CDH patients.

The annual number of CDH patients is very low at most Scandinavian centres, and the complexity of CDH treatment is increasing. Until now no studies on patient volume and outcome of CDH treatment have been published. In other paediatric surgical conditions needing highly specialised treatment, reduced mortality with increased patient load has been documented [35]. Our data suggest a tendency towards increased survival in centres treating more than five CDH patients per year, but the overall difference in survival did not reach significance ( p =0.065). For these reasons, centralisation of CDH management should be considered.