Congenital diaphragmatic hernia (CDH) is a serious congenital abnormality associated with:
- pulmonary hypoplasia, worse on the ipsilateral side
- structural and functional lung immaturity
- a reduction in pulmonary arteriolar cross-sectional area
- muscular hyperplasia of remaining pulmonary arterioles
- an association with other major anomalies, chromosomal and non-chromosomal, in up to 20 per cent of cases.
Around 15-25 cases occur each year in Victoria corresponding to an incidence of approximately 1:3000.
With the virtual universal occurrence of mid trimester ultrasound examination for fetal abnormality more than 80 per cent of cases are now prenatally detected.
The survival rate for all cases diagnosed is approximately 50-60 per cent. If a coexistent significant abnormality is present, survival is less than 10 per cent.
The high mortality rate illustrates the importance of thorough evaluation, from the time of suspected fetal diagnosis, by a multidisciplinary team familiar with all aspects of the diagnosis and management of CDH.
Reported survival for live born infants ranges from 50 to 90 per cent. The international CDH study group database with more than 1,600 patients reports an overall survival of 66 per cent.
The experience for babies managed at the Royal Children's Hospital, Melbourne shows the survival for babies with isolated lesions to be approximately 80 per cent based on more than 240 infants. The difference in survival for all cases versus liveborns reflects the high rate of termination of pregnancy (TOP) where other anomalies are detected, a lower rate of TOP where an isolated lesion is present, as well as a relatively low incidence of stillbirth.
Principles of prenatal care
- Refer for tertiary level obstetric ultrasound.
- If the diagnosis is confirmed refer to a multidisciplinary fetal diagnostic/management team.
The objective of prenatal care should be to:
- Establish an accurate description of the abnormalities present.
- Specify ultrasound features relevant to CDH using a standard form:
- degree of mediastinal shift
- liver/stomach position
- lung: head ratio and observed/expected ratio (LHR standardised for gestation)
- liquor volume.
- Ensure a fetal echocardiogram is performed by a paediatric cardiologist if associated congenital heart disease suspected.
- Do a chromosomal microarray analysis, once informed parental consent is given.
- Provide informed and supportive counselling for the family including a written summary of any discussion with the parents. This summary should include a description of the abnormalities and most likely diagnoses, management options available and possible outcomes.
Ongoing care of CDH includes:
- referral to a paediatric thoracic surgeon if not previously arranged
- regular general obstetric surveillance
- repeat ultrasounds at 24, 30 and 34 weeks to assess fetal growth and features of the CDH as defined above.
Prenatal interventions for CDH include:
- prenatal steroid therapy - recommended according to usual indications (consider at later gestations if birth by caesarean section without labour is anticipated)
- fetal operative intervention (tracheal occlusion) is the subject of ongoing trials. It is not recommended in Victoria where survival rates without fetal intervention are 80 per cent.
The aim is to achieve a normal vaginal birth following spontaneous onset of labour at term, but for pragmatic reasons induction of labour at 38-39 weeks may be offered.
Women who live more than one hour from the perinatal centre are encouraged to move closer to the hospital for birth at 35-36 weeks' gestation. Caesarean section without labour is not recommended unless there is a clear medical indication. It has not been shown to provide better outcome per se, though it is considered in some centres to optimise coordinated care when scheduled in-hours.
Guidelines for neonatal care
Resuscitation (in a tertiary centre)
Resuscitation guidelines include:
- Resuscitation will be individualised according to the condition of the baby and the response to initial steps in resuscitation. However, most babies require intubation.
- Ventilation using a bag and mask should be minimised.
- If endotracheal intubation is required, make sure the tube is not inserted too far into the right main bronchus.
- Intermittent positive pressure ventilation (IPPV), if required, should be provided by a mechanical ventilator at the earliest opportunity.
- Positive pressure ventilation should be accompanied by inspiratory pressure or volume monitoring, where available. There is very limited data on targeted volume ventilation in babies with CDH.
- Babies born in a non tertiary health service should have their respiratory support requirements discussed with the PIPER neonatal consultant while awaiting transfer.
- A large-bore nasogastric tube or Repogle tube should be passed to drain gas from the stomach once the baby has been stabilised in the delivery room.
- Physical contact with the parents should be facilitated before transfer.
- Preductal saturation monitoring should be undertaken during any transfers. In the most critically ill preductal saturations in the 70s and 80s are satisfactory provided sufficient ventilatory support is provided to ensure adequate tidal volume. This is the most difficult situation to get right and in the absence of portable volume monitors. A highly experienced clinician must be supervising this period.
Stabilisation - immediate priorities
Immediate stabilisation priorities include:
- achieve acceptable gas exchange
- saturations > 75 per cent
- pCO2 at 45-55 mmHg, or at a level that allows the pH to be > 7.20 while minimising the chances of inducing lung injury or air leak
- apply a transcutaneous pCO2 monitor
- consult with PIPER and tertiary surgical centre.
Units that report very high survival rates concentrate on minimising lung injury, especially in the initial hours after birth and rarely exceed PIP of 25 cm H2O.
If available use a synchronised mode of ventilation.
To ensure ongoing stabilisation clinicians should:
- Establish venous access - if the baby's condition is poor and the circulation compromised rapidly place a double lumen UV catheter.
- Measure blood pressure and assess the circulation to determine the need for volume support.
- Obtain a chest x-ray.
- Obtain a blood gas by the most expedient route (arterial stab) if the baby's condition remains poor and adjust support accordingly.
- Establish arterial access:
- if urgent - cannulate the UA
- if non urgent then either the procedure can be deferred until the baby has been transferred, or a right radial (preductal) line sited
- do not waste time (and arteries) if the first attempt is unsuccessful.
- Sedate and muscle relax the baby who remains in poor condition despite attempts at optimising ventilation. In particular muscle relaxants should be considered if the baby requires high pressure IPPV (for example, a mean airway pressure of > 14).
- Note that surfactant administration is not recommended in the term baby with CDH.
The baby with a best preductal pO2 < 70 mmHg, or a persistent respiratory or metabolic acidosis despite three to six hours of attempting to optimise ventilatory and circulatory support has a very poor prognosis.
Issues to note about ongoing management of infants with CDH:
- A team of neonatologists, paediatric surgeons and paediatric intensivists is required.
- Ensure continuous monitoring of transcutaneous pCO2, tidal and minute volumes.
- Maintain the lowest FiO2 that results in a preductal saturation > 85 per cent, especially in the initial hours of care. Permissive hypercarbia is strongly advocated.
- Preductal arterial access is desirable if the infant's condition is marginal.
- Assessment for dysmorphism - including echocardiography, renal and cranial sonography and karyotype - should be considered.
- An ongoing metabolic acidosis requiring repeated large doses of base suggest myocardial ischaemia, sepsis or strangulated bowel.
- The principles of management and escalation of therapy include:
- use of muscle relaxants and sedatives
- synchronised ventilation (SIMV or A/C) with tidal/minute volume monitoring
- use point of care echocardiography if possible to guide cardiovascular support (milrinone is a useful agent if there is systolic and diastolic dysfunction)
- pulmonary hypertension treatment may include prostaglandin E infusion (PGE), inhaled nitric oxide (iNO), other vasodilators (low-dose noradrenaline has been reported in small case series to improve oxygenation in the most severe cases)
- HFOV +/- inhaled nitric oxide if the baby has unsatisfactory gas exchange after a reasonable trial of conventional ventilation, or there is an ongoing need for high ventilatory pressures or FiO2
- jet ventilation if there is overt gas trapping or air leak
- ECMO - less than 10 per cent of babies need this.
- Surgery - after ventilatory and circulatory support weaned to satisfactory levels (for example, FiO2 < 0.4 and mean airway pressure < 14)
- Discharge to a special care nursery considered after:
- full enteral nutrition established for at least one week
- respiratory status indicates significant reserve.
- Audiology - arranged prior to discharge if possible.
- Long-term follow up is required.
Hutson, J. et al (eds) Jones Clinical Paediatric Surgery Diagnosis and Management, 6th ed., 2008, Blackwell Publishing
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First published: May 2016
Last web update: October 2018
Review by: May 2019
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Page last updated: 12 Nov 2020